Gold ultra-microelectrode arrays: application to the steady-state voltammetry of hydroxide ion in aqueous solution.

PubMed

Ordeig, Olga; Banks, Craig E; Davies, Trevor J; del Campo, F Javier; Muñoz, Francesc Xavier; Compton, Richard G

2006-05-01

Gold ultra-microelectrode arrays are used to explore the electrochemical oxidation of hydroxide ions and are shown to be analytical useful. Two types of ultra-microelectrode arrays are used; the first consist of 256 individual electrodes of 5 microm in radius, 170 of which are electrochemically active in a cubic arrangement which are separated from their nearest neighbour by a distance of 100 microm. The second array compromises 2597 electrodes of 2.5 microm in radius and of which 1550 of which are electrochemically active in a hexagonal arrangement separated by the nearest neighbour by 55 microm. Well defined voltammetric waves are found with peak currents proportional to the concentration of hydroxide ions in the range 50 microM to 1 mM. Detection limits of 20 microM using the 170 ultra-microelectrode and 10 microM with the 1550 ultra-microelectrode array are shown to be possible but with a higher sensitivity of 4 mA M(-1) observed using the 1550 ultra-microelectrode array compared to 1.2 mA M(-1) with the 170 ultra-microelectrode array.

Digital holographic characterization of liquid microlenses array fabricated in electrode-less configuration

NASA Astrophysics Data System (ADS)

Miccio, L.; Vespini, V.; Grilli, S.; Paturzo, M.; Finizio, A.; De Nicola, S.; Ferraro, P.

2009-06-01

We show how thin liquid film on polar dielectric substrate can form an array of liquid micro-lenses. The effect is driven by the pyroelectric effect leading to a new concept in electro-wetting (EW). EW is a viable method for actuation of liquids in microfluidic systems and requires the design and fabrication of complex electrodes for suitable actuation of liquids. When compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuitless configuration. In our case the surface electric charge induced by the thermal stimulus is able to pattern selectively the surface wettability according to geometry of the ferroelectric domains micro-engineered into the lithium niobate crystal. We show that different geometries of liquid microlenses can be obtained showing also a tuneability of the focal lenses down to 1.6 mm. Thousand of liquid microlenses, each with 100 μm diameter, can be formed and actuated. Also different geometries such as hemi-cylindrical and toroidal liquid structures can be easily obtained. By means of a digital holography method, an accurate characterization of the micro-lenses curvature is performed and presented. The preliminary results concerning the imaging capability of the micro-lens array are also reported. Microlens array can find application in medical stereo-endoscopy, imaging, telecommunication and optical data storage too.

The effect of micro-ECoG substrate footprint on the meningeal tissue response

NASA Astrophysics Data System (ADS)

Schendel, Amelia A.; Nonte, Michael W.; Vokoun, Corinne; Richner, Thomas J.; Brodnick, Sarah K.; Atry, Farid; Frye, Seth; Bostrom, Paige; Pashaie, Ramin; Thongpang, Sanitta; Eliceiri, Kevin W.; Williams, Justin C.

2014-08-01

Objective. There is great interest in designing implantable neural electrode arrays that maximize function while minimizing tissue effects and damage. Although it has been shown that substrate geometry plays a key role in the tissue response to intracortically implanted, penetrating neural interfaces, there has been minimal investigation into the effect of substrate footprint on the tissue response to surface electrode arrays. This study investigates the effect of micro-electrocorticography (micro-ECoG) device geometry on the longitudinal tissue response. Approach. The meningeal tissue response to two micro-ECoG devices with differing geometries was evaluated. The first device had each electrode site and trace individually insulated, with open regions in between, while the second device had a solid substrate, in which all 16 electrode sites were embedded in a continuous insulating sheet. These devices were implanted bilaterally in rats, beneath cranial windows, through which the meningeal tissue response was monitored for one month after implantation. Electrode site impedance spectra were also monitored during the implantation period. Main results. It was observed that collagenous scar tissue formed around both types of devices. However, the distribution of the tissue growth was different between the two array designs. The mesh devices experienced thick tissue growth between the device and the cranial window, and minimal tissue growth between the device and the brain, while the solid device showed the opposite effect, with thick tissue forming between the brain and the electrode sites. Significance. These data suggest that an open architecture device would be more ideal for neural recording applications, in which a low impedance path from the brain to the electrode sites is critical for maximum recording quality.

High Stability Induced by the TiN/Ti Interlayer in Three-Dimensional Si/Ge Nanorod Arrays as Anode in Micro Lithium Ion Battery.

PubMed

Yue, Chuang; Yu, Yingjian; Wu, Zhenguo; Sun, Shibo; He, Xu; Li, Juntao; Zhao, Libo; Wu, Suntao; Li, Jing; Kang, Junyong; Lin, Liwei

2016-03-01

Three-dimensional (3D) Si/Ge-based micro/nano batteries are promising lab-on-chip power supply sources because of the good process compatibility with integrated circuits and Micro/Nano-Electro-Mechanical System technologies. In this work, the effective interlayer of TiN/Ti thin films were introduced to coat around the 3D Si nanorod (NR) arrays before the amorphous Ge layer deposition as anode in micro/nano lithium ion batteries, thus the superior cycling stability was realized by reason for the restriction of Si activation in this unique 3D matchlike Si/TiN/Ti/Ge NR array electrode. Moreover, the volume expansion properties after the repeated lithium-ion insertion/extraction were experimentally investigated to evidence the superior stability of this unique multilayered Si composite electrode. The demonstration of this wafer-scale, cost-effective, and Si-compatible fabrication for anodes in Li-ion micro/nano batteries provides new routes to configurate more efficient 3D energy storage systems for micro/nano smart semiconductor devices.

Liquid micro-lens array activated by selective electrowetting on lithium niobate substrates.

PubMed

Grilli, S; Miccio, L; Vespini, V; Finizio, A; De Nicola, S; Ferraro, Pietro

2008-05-26

Lens effect was obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal like LiNbO3. An array of liquid micro-lenses was generated by electrowetting effect in pyroelectric periodically poled crystals. Compared to conventional electrowetting devices, the pyroelectric effect allowed to have an electrode-less and circuit-less configuration. An interferometric technique was used to characterize the curvature of the micro-lenses and the corresponding results are presented and discussed. The preliminary results concerning the imaging capability of the micro-lens array are also reported.

Carbon nanotubes based methanol sensor for fuel cells application.

PubMed

Kim, D W; Lee, J S; Lee, G S; Overzet, L; Kozlov, M; Aliev, A E; Park, Y W; Yang, D J

2006-11-01

An electrochemical sensor is built using vertically grown multi-walled carbon nanotubes (MWNTs) micro-array to detect methanol concentration in water. This study is done for the potential use of the array as methanol sensor for portable units of direct methanol fuel cells (DMFCs). Platinum (Pt) nanoparticles electro-deposited CNTs (Pt/CNTs) electrode shows high sensitivity in the measurement of methanol concentration in water with cyclic voltammetry (CV) measurement at room temperature. Further investigation has also been undertaken to measure the concentration by changing the amount of the mixture of methanol and formic acid in water. We compared the performance of our micro array sensor built with Pt/CNTs electrodes versus that of Pt wire electrode using CV measurement. We found that our Pt/CNTs array sensor shows high sensitivity and detects methanol concentrations in the range of 0.04 M to 0.10 M. In addition, we found that co-use of formic acid as electrolyte enables us to measure up to 1.0 M methanol concentration.

Design and fabrication of a flexible substrate microelectrode array for brain machine interfaces.

PubMed

Patrick, Erin; Ordonez, Matthew; Alba, Nicolas; Sanchez, Justin C; Nishida, Toshikazu

2006-01-01

We report a neural microelectrode array design that leverages the recording properties of conventional microwire electrode arrays with the additional features of precise control of the electrode geometries. Using microfabrication techniques, a neural probe array is fabricated that possesses a flexible polyimide-based cable. The performance of the design was tested with electrochemical impedance spectroscopy and in vivo studies. The gold-plated electrode site has an impedance value of 0.9 M Omega at 1 kHz. Acute neural recording provided high neuronal yields, peak-to-peak amplitudes (as high as 100 microV), and signal-to-noise ratios (27 dB).

The Electrophysiological MEMS Device with Micro Channel Array for Cellular Network Analysis

NASA Astrophysics Data System (ADS)

Tonomura, Wataru; Kurashima, Toshiaki; Takayama, Yuzo; Moriguchi, Hiroyuki; Jimbo, Yasuhiko; Konishi, Satoshi

This paper describes a new type of MCA (Micro Channel Array) for simultaneous multipoint measurement of cellular network. Presented MCA employing the measurement principles of the patch-clamp technique is designed for advanced neural network analysis which has been studied by co-authors using 64ch MEA (Micro Electrode Arrays) system. First of all, sucking and clamping of cells through channels of developed MCA is expected to improve electrophysiological signal detections. Electrophysiological sensing electrodes integrated around individual channels of MCA by using MEMS (Micro Electro Mechanical System) technologies are electrically isolated for simultaneous multipoint measurement. In this study, we tested the developed MCA using the non-cultured rat's cerebral cortical slice and the hippocampal neurons. We could measure the spontaneous action potential of the slice simultaneously at multiple points and culture the neurons on developed MCA. Herein, we describe the experimental results together with the design and fabrication of the electrophysiological MEMS device with MCA for cellular network analysis.

A Palladium-Tin Modified Microband Electrode Array for Nitrate Determination

PubMed Central

Fu, Yexiang; Bian, Chao; Kuang, Jian; Wang, Jinfen; Tong, Jianhua; Xia, Shanhong

2015-01-01

A microband electrode array modified with palladium-tin bimetallic composite has been developed for nitrate determination. The microband electrode array was fabricated by Micro Electro-Mechanical System (MEMS) technique. Palladium and tin were electrodeposited successively on the electrode, forming a double-layer structure. The effect of the Pd-Sn composite was investigated and its enhancement of catalytic activity and lifetime was revealed. The Pd-Sn modified electrode showed good linearity (R2 = 0.998) from 1 mg/L to 20 mg/L for nitrate determination with a sensitivity of 398 μA/(mg∙L−1∙cm2). The electrode exhibited a satisfying analytical performance after 60 days of storage, indicating a long lifetime. Good repeatability was also displayed by the Pd-Sn modified electrodes. The results provided an option for nitrate determination in water. PMID:26389904

The Electrophysiological Biosensor for Batch-Measurement of Cell Signals

NASA Astrophysics Data System (ADS)

Suzuki, Kengo; Tanabe, Masato; Ezaki, Takahiro; Konishi, Satoshi; Oka, Hiroaki; Ozaki, Nobuhiko

This paper presents the development of electrophysiological biosensor. The developed sensor allows a batch-measurement by detecting all signals from a large number of cells together. The developed sensor employs the same measurement principle as the patch-clamp technique. A single cell is sucked and clamped in a micro hole with detecting electrode. Detecting electrodes in arrayed micro holes are connected together for the batch-measurement of signals a large number of cell signals. Furthermore, an array of sensors for batch-measurement is designed to improve measurement-throughput to satisfy requirements for the drug screening application.

A study of the dynamics of seizure propagation across micro domains in the vicinity of the seizure onset zone.

PubMed

Basu, Ishita; Kudela, Pawel; Korzeniewska, Anna; Franaszczuk, Piotr J; Anderson, William S

2015-08-01

The use of micro-electrode arrays to measure electrical activity from the surface of the brain is increasingly being investigated as a means to improve seizure onset zone (SOZ) localization. In this work, we used a multivariate autoregressive model to determine the evolution of seizure dynamics in the [Formula: see text] Hz high frequency band across micro-domains sampled by such micro-electrode arrays. We showed that a directed transfer function (DTF) can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with known propagation pattern. We used seven complex partial seizures recorded from four patients undergoing intracranial monitoring for surgical evaluation to reconstruct the seizure propagation pattern over sliding windows using a DTF measure. We showed that a DTF can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with a known propagation pattern. In general, depending on the location of the micro-electrode grid with respect to the clinical SOZ and the time from seizure onset, ictal propagation changed in directional characteristics over a 2-10 s time scale, with gross directionality limited to spatial dimensions of approximately [Formula: see text]. It was also seen that the strongest seizure patterns in the high frequency band and their sources over such micro-domains are more stable over time and across seizures bordering the clinically determined SOZ than inside. This type of propagation analysis might in future provide an additional tool to epileptologists for characterizing epileptogenic tissue. This will potentially help narrowing down resection zones without compromising essential brain functions as well as provide important information about targeting anti-epileptic stimulation devices.

A study of the dynamics of seizure propagation across micro domains in the vicinity of the seizure onset zone

NASA Astrophysics Data System (ADS)

Basu, Ishita; Kudela, Pawel; Korzeniewska, Anna; Franaszczuk, Piotr J.; Anderson, William S.

2015-08-01

Objective. The use of micro-electrode arrays to measure electrical activity from the surface of the brain is increasingly being investigated as a means to improve seizure onset zone (SOZ) localization. In this work, we used a multivariate autoregressive model to determine the evolution of seizure dynamics in the 70-110 Hz high frequency band across micro-domains sampled by such micro-electrode arrays. We showed that a directed transfer function (DTF) can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with known propagation pattern. Approach. We used seven complex partial seizures recorded from four patients undergoing intracranial monitoring for surgical evaluation to reconstruct the seizure propagation pattern over sliding windows using a DTF measure. Main results. We showed that a DTF can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with a known propagation pattern. In general, depending on the location of the micro-electrode grid with respect to the clinical SOZ and the time from seizure onset, ictal propagation changed in directional characteristics over a 2-10 s time scale, with gross directionality limited to spatial dimensions of approximately 9 m{{m}2}. It was also seen that the strongest seizure patterns in the high frequency band and their sources over such micro-domains are more stable over time and across seizures bordering the clinically determined SOZ than inside. Significance. This type of propagation analysis might in future provide an additional tool to epileptologists for characterizing epileptogenic tissue. This will potentially help narrowing down resection zones without compromising essential brain functions as well as provide important information about targeting anti-epileptic stimulation devices.

Microengineered Conductive Elastomeric Electrodes for Long-Term Electrophysiological Measurements with Consistent Impedance under Stretch

PubMed Central

Hu, Dinglong; Cheng, Tin Kei; Xie, Kai; Lam, Raymond H. W.

2015-01-01

In this research, we develop a micro-engineered conductive elastomeric electrode for measurements of human bio-potentials with the absence of conductive pastes. Mixing the biocompatible polydimethylsiloxane (PDMS) silicone with other biocompatible conductive nano-particles further provides the material with an electrical conductivity. We apply micro-replica mold casting for the micro-structures, which are arrays of micro-pillars embedded between two bulk conductive-PDMS layers. These micro-structures can reduce the micro-structural deformations along the direction of signal transmission; therefore the corresponding electrical impedance under the physical stretch by the movement of the human body can be maintained. Additionally, we conduct experiments to compare the electrical properties between the bulk conductive-PDMS material and the microengineered electrodes under stretch. We also demonstrate the working performance of these micro-engineered electrodes in the acquisition of the 12-lead electrocardiographs (ECG) of a healthy subject. Together, the presented gel-less microengineered electrodes can provide a more convenient and stable bio-potential measurement platform, making tele-medical care more achievable with reduced technical barriers for instrument installation performed by patients/users themselves. PMID:26512662

Nickel/silicon core/shell nanosheet arrays as electrode materials for lithium ion batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, X.H., E-mail: drhuangxh@hotmail.com; Zhang, P.; Wu, J.B.

Highlights: • Ni nanosheet arrays is the core and Si layer is the shell. • Ni nanosheet arrays act as a three-dimensional current collector to support Si. • Ni nanosheet arrays can improve the conductivity and stability of the electrode. • Ni/Si nanosheet arrays exhibit excellent cyclic and rate performance. - Abstract: Ni/Si core/shell nanosheet arrays are proposed to enhance the electrochemical lithium-storage properties of silicon. The arrays are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The arrays are micro-sized in height, which are constructed by interconnected Ni nanosheet as themore » core and Si coating layer as the shell. The electrochemical properties as anode materials of lithium ion batteries are investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge tests. The arrays can achieve high reversible capacity, good cycle stability and high rate capability. It is believed that the enhanced electrochemical performance is attributed to the electrode structure, because the interconnected Ni nanosheet can act as a three-dimensional current collector, and it has the ability of improving the electrode conductivity, enlarging the electrochemical reaction interface, and suppressing the electrode pulverization.« less

Numerical Simulation of the Diffusion Processes in Nanoelectrode Arrays Using an Axial Neighbor Symmetry Approximation.

PubMed

Peinetti, Ana Sol; Gilardoni, Rodrigo S; Mizrahi, Martín; Requejo, Felix G; González, Graciela A; Battaglini, Fernando

2016-06-07

Nanoelectrode arrays have introduced a complete new battery of devices with fascinating electrocatalytic, sensitivity, and selectivity properties. To understand and predict the electrochemical response of these arrays, a theoretical framework is needed. Cyclic voltammetry is a well-fitted experimental technique to understand the undergoing diffusion and kinetics processes. Previous works describing microelectrode arrays have exploited the interelectrode distance to simulate its behavior as the summation of individual electrodes. This approach becomes limited when the size of the electrodes decreases to the nanometer scale due to their strong radial effect with the consequent overlapping of the diffusional fields. In this work, we present a computational model able to simulate the electrochemical behavior of arrays working either as the summation of individual electrodes or being affected by the overlapping of the diffusional fields without previous considerations. Our computational model relays in dividing a regular electrode array in cells. In each of them, there is a central electrode surrounded by neighbor electrodes; these neighbor electrodes are transformed in a ring maintaining the same active electrode area than the summation of the closest neighbor electrodes. Using this axial neighbor symmetry approximation, the problem acquires a cylindrical symmetry, being applicable to any diffusion pattern. The model is validated against micro- and nanoelectrode arrays showing its ability to predict their behavior and therefore to be used as a designing tool.

A Thin Film Flexible Supercapacitor Based on Oblique Angle Deposited Ni/NiO Nanowire Arrays.

PubMed

Ma, Jing; Liu, Wen; Zhang, Shuyuan; Ma, Zhe; Song, Peishuai; Yang, Fuhua; Wang, Xiaodong

2018-06-11

With high power density, fast charging-discharging speed, and a long cycling life, supercapacitors are a kind of highly developed novel energy-storage device that has shown a growing performance and various unconventional shapes such as flexible, linear-type, stretchable, self-healing, etc. Here, we proposed a rational design of thin film, flexible micro-supercapacitors with in-plane interdigital electrodes, where the electrodes were fabricated using the oblique angle deposition technique to grow oblique Ni/NiO nanowire arrays directly on polyimide film. The obtained electrodes have a high specific surface area and good adhesion to the substrate compared with other in-plane micro-supercapacitors. Meanwhile, the as-fabricated micro-supercapacitors have good flexibility and satisfactory energy-storage performance, exhibiting a high specific capacity of 37.1 F/cm³, a high energy density of 5.14 mWh/cm³, a power density of up to 0.5 W/cm³, and good stability during charge-discharge cycles and repeated bending-recovery cycles, respectively. Our micro-supercapacitors can be used as ingenious energy storage devices for future portable and wearable electronic applications.

Silicon/SU8 multi-electrode micro-needle for in vivo neurochemical monitoring.

PubMed

Vasylieva, Natalia; Marinesco, Stéphane; Barbier, Daniel; Sabac, Andrei

2015-10-15

Simultaneous monitoring of glucose and lactate is an important challenge for understanding brain energetics in physiological or pathological states. We demonstrate here a versatile method based on a minimally invasive single implantation in the rat brain. A silicon/SU8-polymer multi-sensing needle-shaped biosensor, was fabricated and tested. The multi-electrode array design comprises three platinum planar microelectrodes with a surface area of 40 × 200 µm(2) and a spacing of 200 µm, which were micromachined on a single 3mm long micro-needle having a 100 × 50 µm(2) cross-section for reduced tissue damage during implantation. Platinum micro-electrodes were aligned at the bottom of micro-wells obtained by photolithography on a SU8 photoresist layer. After clean room processing, each micro-electrode was functionalized inside the micro-wells by means of a micro-dispensing device, either with glucose oxidase or with lactate oxidase, which were cross-linked on the platinum electrodes. The third electrode covered with Bovine Serum Albumin (BSA) was used for the control of non-specific currents. The thick SU8 photoresist layer has revealed excellent electrical insulation of the micro-electrodes and between interconnection lines, and ensured a precise localization and packaging of the sensing enzymes on platinum micro-electrodes. During in vitro calibration with concentrations of analytes in the mM range, the micro-wells patterned in the SU8 photoresist proved to be highly effective in eliminating cross-talk signals, caused by H2O2 diffusion from closely spaced micro-electrodes. Moreover, our biosensor was successfully assayed in the rat cortex for simultaneous monitoring of both glucose and lactate during insulin and glucose administration. Copyright © 2015 Elsevier B.V. All rights reserved.

In vitro cyto-biocompatibility study of thin-film transistors substrates using an organotypic culture method.

PubMed

Leclerc, Eric; Duval, Jean-Luc; Egles, Christophe; Ihida, Satoshi; Toshiyoshi, Hiroshi; Tixier-Mita, Agnès

2017-01-01

Thin-Film-Transistors Liquid-Crystal Display has become a standard in the field of displays. However, the structure of these devices presents interest not only in that field, but also for biomedical applications. One of the key components, called here TFT substrate, is a glass substrate with a dense and large array of thousands of transparent micro-electrodes that can be considered as a large scale multi-electrode array(s). Multi-electrode array(s) are widely used for in vitro electrical investigations on neurons and brain, allowing excitation, registration, and recording of their activity. However, the range of application of conventional multi-electrode array(s) is usually limited to some tens of cells in a homogeneous cell culture, because of a small area, small number and a low density of the micro-electrodes. TFT substrates do not have these limitations and the authors are currently studying the possibility to use TFT substrates as new tools for in vitro electrical investigation on tissues and organoids. In this respect, experiments to determine the cyto-biocompatibility of TFT substrates with tissues were conducted and are presented in this study. The investigation was performed using an organotypic culture method with explants of brain and liver tissues of chick embryos. The results in term of morphology, cell migration, cell density and adhesion were compared with the results from Thermanox ® , a conventional plastic for cell culture, and with polydimethylsiloxane, a hydrophobic silicone. The results with TFT substrates showed similar results as for the Thermanox ® , despite the TFT hydrophobicity. TFT substrates have a weak cell adhesion and promote cell migration similarly to Thermanox ® . It could be concluded that the TFT substrates are cyto-biocompatible with the two studied organs.

Fabrication and surface-modification of implantable microprobes for neuroscience studies

NASA Astrophysics Data System (ADS)

Cao, H.; Nguyen, C. M.; Chiao, J. C.

2012-06-01

In this work implantable micro-probes for central nervous system (CNS) studies were developed on silicon and polyimide substrates. The probes which contained micro-electrode arrays with different surface modifications were designed for implantation in the CNS. The electrode surfaces were modified with nano-scale structures that could greatly increase the active surface area in order to enhance the electrochemical current outputs while maintaining micro-scale dimensions of the electrodes and probes. The electrodes were made of gold or platinum, and designed with different sizes. The silicon probes were modified by silicon nanowires fabricated with the vapor-liquid-solid mechanism at high temperatures. With polyimide substrates, the nanostructure modification was carried out by applying concentrated gold or silver colloid solutions onto the micro-electrodes at room temperature. The surfaces of electrodes before and after modification were observed by scanning electron microscopy. The silicon nanowire-modified surface was characterized by cyclic voltammetry. Experiments were carried out to investigate the improvement in sensing performance. The modified electrodes were tested with H2O2, electrochemical L-glutamate and dopamine. Comparisons between electrodes with and without nanostructure modification were conducted showing that the modifications have enhanced the signal outputs of the electrochemical neurotransmitter sensors.

Direct electronic communication at bio-interfaces assisted by layered-metal-hydroxide slab arrays with controlled nano-micro structures.

PubMed

An, Zhe; He, Jing

2011-10-28

The electronic transfer (eT) at bio-interfaces has been achieved by orientating 2D inorganic slabs in a regular arrangement with the slab ab-planes vertical to the electrode substrate. The eT rate is effectively promoted by tuning the nano-micro scale structures of perpendicular LDH arrays. This journal is © The Royal Society of Chemistry 2011

Design and fabrication of AlGaInP-based micro-light-emitting-diode array devices

NASA Astrophysics Data System (ADS)

Bao, Xingzhen; Liang, Jingqiu; Liang, Zhongzhu; Wang, Weibiao; Tian, Chao; Qin, Yuxin; Lü, Jinguang

2016-04-01

An integrated high-resolution (individual pixel size 80 μm×80 μm) solid-state self-emissive active matrix programmed with 320×240 micro-light-emitting-diode arrays structure was designed and fabricated on an AlGaInP semiconductor chip using micro electro-mechanical systems, microstructure and semiconductor fabricating techniques. Row pixels share a p-electrode and line pixels share an n-electrode. We experimentally investigated GaAs substrate thickness affects the electrical and optical characteristics of the pixels. For a 150-μm-thick GaAs substrate, the single pixel output power was 167.4 μW at 5 mA, and increased to 326.4 μW when current increase to 10 mA. The device investigated potentially plays an important role in many fields.

Development and Evaluation of Micro-Electrocorticography Arrays for Neural Interfacing Applications

NASA Astrophysics Data System (ADS)

Schendel, Amelia Ann

Neural interfaces have great promise for both electrophysiological research and therapeutic applications. Whether for the study of neural circuitry or for neural prosthetic or other therapeutic applications, micro-electrocorticography (micro-ECoG) arrays have proven extremely useful as neural interfacing devices. These devices strike a balance between invasiveness and signal resolution, an important step towards eventual human application. The objective of this research was to make design improvements to micro-ECoG devices to enhance both biocompatibility and device functionality. To best evaluate the effectiveness of these improvements, a cranial window imaging method for in vivo monitoring of the longitudinal tissue response post device implant was developed. Employment of this method provided valuable insight into the way tissue grows around micro-ECoG arrays after epidural implantation, spurring a study of the effects of substrate geometry on the meningeal tissue response. The results of the substrate footprint comparison suggest that a more open substrate geometry provides an easy path for the tissue to grow around to the top side of the device, whereas a solid device substrate encourages the tissue to thicken beneath the device, between the electrode sites and the brain. The formation of thick scar tissue between the recording electrode sites and the neural tissue is disadvantageous for long-term recorded signal quality, and thus future micro-ECoG device designs should incorporate open-architecture substrates for enhanced longitudinal in vivo function. In addition to investigating improvements for long-term device reliability, it was also desired to enhance the functionality of micro-ECoG devices for neural electrophysiology research applications. To achieve this goal, a completely transparent graphene-based device was fabricated for use with the cranial window imaging method and optogenetic techniques. The use of graphene as the conductive material provided the transparency necessary to image tissues directly below the micro-ECoG electrode sites, and to transmit light through the electrode sites to underlying neural tissue, for optical stimulation of neural cells. The flexibility and broad-spectrum transparency of graphene make it an ideal choice for thin-film, flexible electronic devices.

Fabrication of Micro-Needle Electrodes for Bio-Signal Recording by a Magnetization-Induced Self-Assembly Method

PubMed Central

Chen, Keyun; Ren, Lei; Chen, Zhipeng; Pan, Chengfeng; Zhou, Wei; Jiang, Lelun

2016-01-01

Micro-needle electrodes (MEs) have attracted more and more attention for monitoring physiological electrical signals, including electrode-skin interface impedance (EII), electromyography (EMG) and electrocardiography (ECG) recording. A magnetization-induced self-assembling method (MSM) was developed to fabricate a microneedle array (MA). A MA coated with Ti/Au film was assembled as a ME. The fracture and insertion properties of ME were tested by experiments. The bio-signal recording performance of the ME was measured and compared with a typical commercial wet electrode (Ag/AgCl electrode). The results show that the MA self-assembled from the magnetic droplet array under the sum of gravitational surface tension and magnetic potential energies. The ME had good toughness and could easily pierce rabbit skin without being broken or buckling. When the compression force applied on the ME was larger than 2 N, ME could stably record EII, which was a lower value than that measured by Ag/AgCl electrodes. EMG signals collected by ME varied along with the contraction of biceps brachii muscle. ME could record static ECG signals with a larger amplitude and dynamic ECG signals with more distinguishable features in comparison with a Ag/AgCl electrode, therefore, ME is an alternative electrode for bio-signal monitoring in some specific situations. PMID:27657072

A study of the dynamics of seizure propagation across micro domains in the vicinity of the seizure onset zone

PubMed Central

Basu, Ishita; Kudela, Pawel; Korzeniewska, Anna; Franaszczuk, Piotr J.; Anderson, William S.

2015-01-01

Objective The use of micro-electrode arrays to measure electrical activity from the surface of the brain is increasingly being investigated as a means to improve seizure onset zone localization. In this work, we used a multivariate autoregressive model to determine the evolution of seizure dynamics in the 70 – 110 Hz high frequency band across micro-domains sampled by such micro-electrode arrays. Approach We used 7 complex partial seizures recorded from 4 patients undergoing intracranial monitoring for surgical evaluation to reconstruct the seizure propagation pattern over sliding windows using a directed transfer function measure. Main results We showed that a directed transfer function can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with known propagation pattern. In general, depending on the location of the micro-electrode grid with respect to the clinical seizure onset zone and the time from seizure onset, ictal propagation changed in directional characteristics over a 2 to 10 seconds time scale, with gross directionality limited to spatial dimensions of approximately 9mm2. It was also seen that the strongest seizure patterns in the high frequency band and their sources over such micro-domains are more stable over time and across seizures bordering the clinically determined seizure onset zone than inside. Significance This type of propagation analysis might in future provide an additional tool to epileptologists for characterizing epileptogenic tissue. This will potentially help narrowing down resection zones without compromising essential brain functions as well as provide important information about targeting anti-epileptic stimulation devices. PMID:26061006

Mapping the fine structure of cortical activity with different micro-ECoG electrode array geometries

NASA Astrophysics Data System (ADS)

Wang, Xi; Gkogkidis, C. Alexis; Iljina, Olga; Fiederer, Lukas D. J.; Henle, Christian; Mader, Irina; Kaminsky, Jan; Stieglitz, Thomas; Gierthmuehlen, Mortimer; Ball, Tonio

2017-10-01

Objective. Innovations in micro-electrocorticography (µECoG) electrode array manufacturing now allow for intricate designs with smaller contact diameters and/or pitch (i.e. inter-contact distance) down to the sub-mm range. The aims of the present study were: (i) to investigate whether frequency ranges up to 400 Hz can be reproducibly observed in µECoG recordings and (ii) to examine how differences in topographical substructure between these frequency bands and electrode array geometries can be quantified. We also investigated, for the first time, the influence of blood vessels on signal properties and assessed the influence of cortical vasculature on topographic mapping. Approach. The present study employed two µECoG electrode arrays with different contact diameters and inter-contact distances, which were used to characterize neural activity from the somatosensory cortex of minipigs in a broad frequency range up to 400 Hz. The analysed neural data were recorded in acute experiments under anaesthesia during peripheral electrical stimulation. Main results. We observed that µECoG recordings reliably revealed multi-focal cortical somatosensory response patterns, in which response peaks were often less than 1 cm apart and would thus not have been resolvable with conventional ECoG. The response patterns differed by stimulation site and intensity, they were distinct for different frequency bands, and the results of functional mapping proved independent of cortical vascular. Our analysis of different frequency bands exhibited differences in the number of activation peaks in topographical substructures. Notably, signal strength and signal-to-noise ratios differed between the two electrode arrays, possibly due to their different sensitivity for variations in spatial patterns and signal strengths. Significance. Our findings that the geometry of µECoG electrode arrays can strongly influence their recording performance can help to make informed decisions that maybe important in number of clinical contexts, including high-resolution brain mapping, advanced epilepsy diagnostics or brain-machine interfacing.

Colloidal-gold electrosensor measuring device

DOEpatents

Wegner, S.; Harpold, M.A.; McCaffrey, T.M.; Morris, S.E.; Wojciechowski, M.; Zhao, J.; Henkens, R.W.; Naser, N.; O`Daly, J.P.

1995-11-21

The present invention provides a new device for use in measuring lead levels in biological and environmental samples. Using square wave coulometry and colloidal gold particles impregnated on carbon electrodes, the present invention provides a rapid, reliable, portable and inexpensive means of detecting low lead levels. The colloidal gold modified electrodes have microelectrode array characteristics and produce significantly higher stripping detection signals for lead than are produced at bulk gold electrode surfaces. The method is effective in determining levels of lead down to at least 5 {micro}g/dL in blood samples as small as 10 {micro}L. 9 figs.

Rapid prototyping of flexible intrafascicular electrode arrays by picosecond laser structuring.

PubMed

Mueller, Matthias; de la Oliva, Natalia; Del Valle, Jaume; Delgado-Martínez, Ignacio; Navarro, Xavier; Stieglitz, Thomas

2017-12-01

Interfacing the peripheral nervous system can be performed with a large variety of electrode arrays. However, stimulating and recording a nerve while having a reasonable amount of channels limits the number of available systems. Translational research towards human clinical trial requires device safety and biocompatibility but would benefit from design flexibility in the development process to individualize probes. We selected established medical grade implant materials like precious metals and Parylene C to develop a rapid prototyping process for novel intrafascicular electrode arrays using a picosecond laser structuring. A design for a rodent animal model was developed in conjunction with an intrafascicular implantation strategy. Electrode characterization and optimization was performed first in saline solution in vitro before performance and biocompatibility were validated in sciatic nerves of rats in chronic implantation. The novel fabrication process proved to be suitable for prototyping and building intrafascicular electrode arrays. Electrochemical properties of the electrode sites were enhanced and tested for long-term stability. Chronic implantation in the sciatic nerve of rats showed good biocompatibility, selectivity and stable stimulation thresholds. Established medical grade materials can be used for intrafascicular nerve electrode arrays when laser structuring defines structure size in the micro-scale. Design flexibility reduces re-design cycle time and material certificates are beneficial support for safety studies on the way to clinical trials.

Design of Architectures and Materials in In-Plane Micro-supercapacitors: Current Status and Future Challenges.

PubMed

Qi, Dianpeng; Liu, Yan; Liu, Zhiyuan; Zhang, Li; Chen, Xiaodong

2017-02-01

The rapid development of integrated electronics and the boom in miniaturized and portable devices have increased the demand for miniaturized and on-chip energy storage units. Currently thin-film batteries or microsized batteries are commercially available for miniaturized devices. However, they still suffer from several limitations, such as short lifetime, low power density, and complex architecture, which limit their integration. Supercapacitors can surmount all these limitations. Particularly for micro-supercapacitors with planar architectures, due to their unique design of the in-plane electrode finger arrays, they possess the merits of easy fabrication and integration into on-chip miniaturized electronics. Here, the focus is on the different strategies to design electrode finger arrays and the material engineering of in-plane micro-supercapacitors. It is expected that the advances in micro-supercapacitors with in-plane architectures will offer new opportunities for the miniaturization and integration of energy-storage units for portable devices and on-chip electronics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Method and apparatus for detection of charge on ions and particles

DOEpatents

Fuerstenau, Stephen Douglas; Soli, George Arthur

2002-01-01

The present invention provides a tessellated array detector with charge collecting plate (or cup) electrode pixels and amplifying circuitry integrated into each pixel making it sensitive to external electrostatic charge; a micro collector/amplifier pixel design possessing a small capacitance to ensure a high charge to voltage signal conversion for low noise/high sensitivity operation; a micro-fabricated array of such pixels to create a useful macroscopic target area for ion and charged particle collection.

Using Arrays of Microelectrodes Implanted in Residual Peripheral Nerves to Provide Dexterous Control of, and Modulated Sensory Feedback from, a Hand Prosthesis

DTIC Science & Technology

2017-10-01

potentials or multi-action potential activity from residual peripheral nerve while patient intends movements of amputated hand/arm Subtask 3.1: Mapping of...neural activity (Months 4 – 36) • Patients will be asked to intend a number of individual finger and multiple finger flexion, extension, adduction...intended movements. We will map the different intended movements onto the neural activity recorded on the electrodes of the micro-electrode array

Fabrication of polymeric nano-batteries array using anodic aluminum oxide templates.

PubMed

Zhao, Qiang; Cui, Xiaoli; Chen, Ling; Liu, Ling; Sun, Zhenkun; Jiang, Zhiyu

2009-02-01

Rechargeable nano-batteries were fabricated in the array pores of anodic aluminum oxide (AAO) template, combining template method and electrochemical method. The battery consisted of electropolymerized PPy electrode, porous TiO2 separator, and chemically polymerized PAn electrode was fabricated in the array pores of two-step anodizing aluminum oxide (AAO) membrane, based on three-step assembling method. It performs typical electrochemical battery behavior with good charge-discharge ability, and presents a capacity of 25 nAs. AFM results show the hexagonal array of nano-batteries' top side. The nano-battery may be a promising device for the development of Micro-Electro-Mechanical Systems (MEMS), and Nano-Electro-Mechanical Systems (NEMS).

Single electrode micro-stimulation of rat auditory cortex: an evaluation of behavioral performance.

PubMed

Rousche, Patrick J; Otto, Kevin J; Reilly, Mark P; Kipke, Daryl R

2003-05-01

A combination of electrophysiological mapping, behavioral analysis and cortical micro-stimulation was used to explore the interrelation between the auditory cortex and behavior in the adult rat. Auditory discriminations were evaluated in eight rats trained to discriminate the presence or absence of a 75 dB pure tone stimulus. A probe trial technique was used to obtain intensity generalization gradients that described response probabilities to mid-level tones between 0 and 75 dB. The same rats were then chronically implanted in the auditory cortex with a 16 or 32 channel tungsten microwire electrode array. Implanted animals were then trained to discriminate the presence of single electrode micro-stimulation of magnitude 90 microA (22.5 nC/phase). Intensity generalization gradients were created to obtain the response probabilities to mid-level current magnitudes ranging from 0 to 90 microA on 36 different electrodes in six of the eight rats. The 50% point (the current level resulting in 50% detections) varied from 16.7 to 69.2 microA, with an overall mean of 42.4 (+/-8.1) microA across all single electrodes. Cortical micro-stimulation induced sensory-evoked behavior with similar characteristics as normal auditory stimuli. The results highlight the importance of the auditory cortex in a discrimination task and suggest that micro-stimulation of the auditory cortex might be an effective means for a graded information transfer of auditory information directly to the brain as part of a cortical auditory prosthesis.

Neuro-Prosthetic Implants With Adjustable Electrode Arrays

NASA Technical Reports Server (NTRS)

Whitacre, Jay; DelCastillo, Linda Y.; Mojarradi, Mohammad; Johnson, Travis; West, William; Andersen, Richard

2006-01-01

Brushlike arrays of electrodes packaged with application-specific integrated circuits (ASICs) are undergoing development for use as electronic implants especially as neuro-prosthetic devices that might be implanted in brains to detect weak electrical signals generated by neurons. These implants partly resemble the ones reported in Integrated Electrode Arrays for Neuro-Prosthetic Implants (NPO-21198), NASA Tech Briefs, Vol. 27, No. 2 (February 2003), page 48. The basic idea underlying both the present and previously reported implants is that the electrodes would pick up signals from neurons and the ASICs would amplify and otherwise preprocess the signals for monitoring by external equipment. The figure presents a simplified and partly schematic view of an implant according to the present concept. Whereas the electrodes in an implant according to the previously reported concept would be microscopic wires, the electrodes according to the present concept are in the form of microscopic needles. An even more important difference would be that, unlike the previously reported concept, the present concept calls for the inclusion of microelectromechanical actuators for adjusting the depth of penetration of the electrodes into brain tissue. The prototype implant now under construction includes an array of 100 electrodes and corresponding array of electrode contact pads formed on opposite faces of a plate fabricated by techniques that are established in the art of microelectromechanical systems (MEMS). A mixed-signal ASIC under construction at the time of reporting the information for this article will include 100 analog amplifier channels (one amplifier per electrode). On one face of the mixed-signal ASIC there will be a solder-bump/micro-pad array that will have the same pitch as that of the electrode array, and that will be used to make the electrical and mechanical connections between the electrode array and the ASIC. Once the electrode array and the ASIC are soldered together, the remaining empty space between them will be filled with a biocompatible epoxy, the remaining exposed portions of the ASIC will be covered with micromachined plates for protection against corrosive bodily fluids, and then the ASIC and its covering micromachined plates will be coated with parylene

Combinatorial electrochemical cell array for high throughput screening of micro-fuel-cells and metal/air batteries.

PubMed

Jiang, Rongzhong

2007-07-01

An electrochemical cell array was designed that contains a common air electrode and 16 microanodes for high throughput screening of both fuel cells (based on polymer electrolyte membrane) and metal/air batteries (based on liquid electrolyte). Electrode materials can easily be coated on the anodes of the electrochemical cell array and screened by switching a graphite probe from one cell to the others. The electrochemical cell array was used to study direct methanol fuel cells (DMFCs), including high throughput screening of electrode catalysts and determination of optimum operating conditions. For screening of DMFCs, there is about 6% relative standard deviation (percentage of standard deviation versus mean value) for discharge current from 10 to 20 mAcm(2). The electrochemical cell array was also used to study tin/air batteries. The effect of Cu content in the anode electrode on the discharge performance of the tin/air battery was investigated. The relative standard deviations for screening of metal/air battery (based on zinc/air) are 2.4%, 3.6%, and 5.1% for discharge current at 50, 100, and 150 mAcm(2), respectively.

Microfluidic in-channel multi-electrode platform for neurotransmitter sensing

NASA Astrophysics Data System (ADS)

Kara, A.; Mathault, J.; Reitz, A.; Boisvert, M.; Tessier, F.; Greener, J.; Miled, A.

2016-03-01

In this project we present a microfluidic platform with in-channel micro-electrodes for in situ screening of bio/chemical samples through a lab-on-chip system. We used a novel method to incorporate electrochemical sensors array (16x20) connected to a PCB, which opens the way for imaging applications. A 200 μm height microfluidic channel was bonded to electrochemical sensors. The micro-channel contains 3 inlets used to introduce phosphate buffer saline (PBS), ferrocynide and neurotransmitters. The flow rate was controlled through automated micro-pumps. A multiplexer was used to scan electrodes and perform individual cyclic voltammograms by a custom potentiostat. The behavior of the system was linear in terms of variation of current versus concentration. It was used to detect the neurotransmitters serotonin, dopamine and glutamate.

Rapid prototyping of flexible intrafascicular electrode arrays by picosecond laser structuring

NASA Astrophysics Data System (ADS)

Mueller, Matthias; de la Oliva, Natalia; del Valle, Jaume; Delgado-Martínez, Ignacio; Navarro, Xavier; Stieglitz, Thomas

2017-12-01

Objective. Interfacing the peripheral nervous system can be performed with a large variety of electrode arrays. However, stimulating and recording a nerve while having a reasonable amount of channels limits the number of available systems. Translational research towards human clinical trial requires device safety and biocompatibility but would benefit from design flexibility in the development process to individualize probes. Approach. We selected established medical grade implant materials like precious metals and Parylene C to develop a rapid prototyping process for novel intrafascicular electrode arrays using a picosecond laser structuring. A design for a rodent animal model was developed in conjunction with an intrafascicular implantation strategy. Electrode characterization and optimization was performed first in saline solution in vitro before performance and biocompatibility were validated in sciatic nerves of rats in chronic implantation. Main results. The novel fabrication process proved to be suitable for prototyping and building intrafascicular electrode arrays. Electrochemical properties of the electrode sites were enhanced and tested for long-term stability. Chronic implantation in the sciatic nerve of rats showed good biocompatibility, selectivity and stable stimulation thresholds. Significance. Established medical grade materials can be used for intrafascicular nerve electrode arrays when laser structuring defines structure size in the micro-scale. Design flexibility reduces re-design cycle time and material certificates are beneficial support for safety studies on the way to clinical trials.

The Effect of Scala Tympani Morphology on Basilar Membrane Contact With a Straight Electrode Array: A Human Temporal Bone Study.

PubMed

Verberne, Juul; Risi, Frank; Campbell, Luke; Chambers, Scott; O'Leary, Stephen

2017-01-01

Scala tympani morphology influences the insertion dynamics and intra-scalar position of straight electrode arrays. Hearing preservation is the goal of cochlear implantation with current thin straight electrode arrays. These hug the lateral wall, facilitating full, atraumatic insertions. However, most studies still report some postoperative hearing loss. This study explores the influence of scala tympani morphology on array position relative to the basilar membrane and its possible contribution to postoperative hearing loss. Twenty-six fresh-frozen human temporal bones implanted with a straight electrode array were three-dimensionally reconstructed from micro-photographic histological sections. Insertion depth and the proximity between the array and basilar membrane were recorded. Lateral wall shape was quantified as a curvature ratio. Insertion depths ranged from 233 to 470 degrees. The mean first point of contact between the array and basilar membrane was 185 degrees; arrays tended to remain in contact with the membrane after first contacting it. Eighty-nine and 93% of arrays that reached the upper basal (>240-360 degrees) and second (>360-720 degrees) turns respectively contacted the basilar membrane in these regions. Scalar wall curvature ratio decreased significantly (the wall became steeper) from the basal to second turns. This shift correlated with a reduced distance between the array and basilar membrane. Scala tympani morphology influences the insertion dynamics and intra-scalar position of a straight electrode array. In addition to gross trauma of cochlear structures, contact between the array and basilar membrane and how this impacts membrane function should be considered in hearing preservation cases.

The rational for a mid-scala electrode array.

PubMed

Boyle, P J

2016-06-01

Today increasing numbers of cochlear implant candidates have residual hearing that can be aided and hence is worth trying to preserve. This means that surgical technique and electrode array design must be adapted to minimize trauma. Wide opening of the round window is often preferred to reduce drill related trauma and to avoid pressure spikes during electrode array insertion. A recent meta-analysis suggested that there is no significant correlation between hearing preservation and either insertion depth or scala position. However, a slow insertion speed of at least 30seconds was associated with better hearing preservation. An electrode design is proposed that targets the middle of the scala tympani. This minimizes frictional forces from either lateral or medial wall during insertion and imposes less static pressure on cochlear structures following insertion. The flexibility to insert via the round window requires a 0.7-mm maximum dimension at the proximal end of the array. Micro-anatomical analysis by micro-CT indicated that a 420-degree insertion depth was optimal between cochlear coverage and available space within the scala tympani. Physical measurements showed that mean insertion forces remained below 10mN during insertion. A series of 20 human temporal bone insertions found a mean insertion depth of 400 degrees with no scala dislocations. Six clinical series, in total 94 cases, found postoperative hearing in 81% of cases with a mean loss of 12dB compared to preoperative levels. Speech understanding out to one year post-fitting trended better for a mid-scala design group than for a straight electrode array group; although the differences were not statistically significant. A mid-scala array design appears able to be inserted with minimal trauma, to return a predictable insertion depth across various sizes of cochleae and to support reasonable levels of speech understanding without relying on residual hearing. Copyright © 2016. Published by Elsevier Masson SAS.

Evaluation of the hybrid-L24 electrode using microcomputed tomography.

PubMed

Driscoll, Colin L W; Carlson, Matthew L; Fama, Anthony F; Lane, John I

2011-07-01

To compare electrode array position, and depth of insertion of the Cochlear Hybrid-L24 electrode array following traditional cochleostomy and round window (RW) insertion. Prospective cadaveric temporal bone study. Ten cadaveric temporal bones were implanted with the Hybrid-L24 electrode array; half were introduced through a RW approach, whereas the other half were inserted through a traditional scala tympani cochleostomy. A micro-CT scanner was then used to evaluate electrode position, intracochlear trauma, and depth of insertion. All electrodes were inserted into the scala tympani without significant resistance. No electrodes demonstrated tip fold-over or through-fracturing of the osseous spiral lamina, basilar membrane, or spiral ligament. The average angular depth of insertion for all 10 electrodes was 252.4°. Compared to cochleostomy insertions, electrodes inserted through the RW more commonly acquired a proximal perimodiolar orientation, followed a more predictable course, and less commonly contacted critical soft tissue structures. The results of this study demonstrate that the Hybrid-L24 electrode can be successfully inserted using a RW or traditional cochleostomy technique with minimal intracochlear trauma. Our data also suggests that with this model, RW insertions may provide particular advantages with respect to hearing preservation over the traditional cochleostomy approach. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

Enhanced lifetime for thin-dielectric microdischarge-arrays operating in DC

NASA Astrophysics Data System (ADS)

Dussart, Remi; Felix, Valentin; Overzet, Lawrence; Aubry, Olivier; Stolz, Arnaud; Lefaucheux, Philippe; Gremi-Univ Orleans-Cnrs Collaboration; University Of Texas At Dallas Collaboration

2016-09-01

Micro-hollow cathode discharge arrays using silicon as the cathode have a very limited lifetime because the silicon bubbles and initiates micro-arcing. To avoid this destructive behavior, the same configuration was kept but, another material was selected for the cathode. Using micro and nanotechnologies ordinarily used in microelectronic and MEMS device fabrication, we made arrays of cathode boundary layer (CBL)-type microreactors consisting of nickel electrodes separated by a 6 µm thick SiO2 layer. Microdischarges were ignited in arrays of 100 µm diameter holes at different pressures (200750 Torr) in different gases. Electrical and optical measurements were made to characterize the arrays. Unlike the microdischarges produced using silicon cathodes, the Ni cathode discharges remain very stable with essentially no micro-arcing. DC currents between 50 and 900 µA flowed through each microreactor with a discharge voltage of typically 200 V. Stable V-I characteristics showing both the normal and abnormal regimes were observed and are consistent with the spread of the plasma over the cathode area. Due to their stability and lifetime, new applications of these DC, CBL-type microreactors can now be envisaged.

Accurate motor mapping in awake common marmosets using micro-electrocorticographical stimulation and stochastic threshold estimation

NASA Astrophysics Data System (ADS)

Kosugi, Akito; Takemi, Mitsuaki; Tia, Banty; Castagnola, Elisa; Ansaldo, Alberto; Sato, Kenta; Awiszus, Friedemann; Seki, Kazuhiko; Ricci, Davide; Fadiga, Luciano; Iriki, Atsushi; Ushiba, Junichi

2018-06-01

Objective. Motor map has been widely used as an indicator of motor skills and learning, cortical injury, plasticity, and functional recovery. Cortical stimulation mapping using epidural electrodes is recently adopted for animal studies. However, several technical limitations still remain. Test-retest reliability of epidural cortical stimulation (ECS) mapping has not been examined in detail. Many previous studies defined evoked movements and motor thresholds by visual inspection, and thus, lacked quantitative measurements. A reliable and quantitative motor map is important to elucidate the mechanisms of motor cortical reorganization. The objective of the current study was to perform reliable ECS mapping of motor representations based on the motor thresholds, which were stochastically estimated by motor evoked potentials and chronically implanted micro-electrocorticographical (µECoG) electrode arrays, in common marmosets. Approach. ECS was applied using the implanted µECoG electrode arrays in three adult common marmosets under awake conditions. Motor evoked potentials were recorded through electromyographical electrodes implanted in upper limb muscles. The motor threshold was calculated through a modified maximum likelihood threshold-hunting algorithm fitted with the recorded data from marmosets. Further, a computer simulation confirmed reliability of the algorithm. Main results. Computer simulation suggested that the modified maximum likelihood threshold-hunting algorithm enabled to estimate motor threshold with acceptable precision. In vivo ECS mapping showed high test-retest reliability with respect to the excitability and location of the cortical forelimb motor representations. Significance. Using implanted µECoG electrode arrays and a modified motor threshold-hunting algorithm, we were able to achieve reliable motor mapping in common marmosets with the ECS system.

Accurate motor mapping in awake common marmosets using micro-electrocorticographical stimulation and stochastic threshold estimation.

PubMed

Kosugi, Akito; Takemi, Mitsuaki; Tia, Banty; Castagnola, Elisa; Ansaldo, Alberto; Sato, Kenta; Awiszus, Friedemann; Seki, Kazuhiko; Ricci, Davide; Fadiga, Luciano; Iriki, Atsushi; Ushiba, Junichi

2018-06-01

Motor map has been widely used as an indicator of motor skills and learning, cortical injury, plasticity, and functional recovery. Cortical stimulation mapping using epidural electrodes is recently adopted for animal studies. However, several technical limitations still remain. Test-retest reliability of epidural cortical stimulation (ECS) mapping has not been examined in detail. Many previous studies defined evoked movements and motor thresholds by visual inspection, and thus, lacked quantitative measurements. A reliable and quantitative motor map is important to elucidate the mechanisms of motor cortical reorganization. The objective of the current study was to perform reliable ECS mapping of motor representations based on the motor thresholds, which were stochastically estimated by motor evoked potentials and chronically implanted micro-electrocorticographical (µECoG) electrode arrays, in common marmosets. ECS was applied using the implanted µECoG electrode arrays in three adult common marmosets under awake conditions. Motor evoked potentials were recorded through electromyographical electrodes implanted in upper limb muscles. The motor threshold was calculated through a modified maximum likelihood threshold-hunting algorithm fitted with the recorded data from marmosets. Further, a computer simulation confirmed reliability of the algorithm. Computer simulation suggested that the modified maximum likelihood threshold-hunting algorithm enabled to estimate motor threshold with acceptable precision. In vivo ECS mapping showed high test-retest reliability with respect to the excitability and location of the cortical forelimb motor representations. Using implanted µECoG electrode arrays and a modified motor threshold-hunting algorithm, we were able to achieve reliable motor mapping in common marmosets with the ECS system.

A High-Voltage Integrated Circuit Engine for a Dielectrophoresis-based Programmable Micro-Fluidic Processor

PubMed Central

Current, K. Wayne; Yuk, Kelvin; McConaghy, Charles; Gascoyne, Peter R. C.; Schwartz, Jon A.; Vykoukal, Jody V.; Andrews, Craig

2010-01-01

A high-voltage (HV) integrated circuit has been demonstrated to transport droplets on programmable paths across its coated surface. This chip is the engine for a dielectrophoresis (DEP)-based micro-fluidic lab-on-a-chip system. This chip creates DEP forces that move and help inject droplets. Electrode excitation voltage and frequency are variable. With the electrodes driven with a 100V peak-to-peak periodic waveform, the maximum high-voltage electrode waveform frequency is about 200Hz. Data communication rate is variable up to 250kHz. This demonstration chip has a 32×32 array of nominally 100V electrode drivers. It is fabricated in a 130V SOI CMOS fabrication technology, dissipates a maximum of 1.87W, and is about 10.4 mm × 8.2 mm. PMID:23989241

Microprobe array with low impedance electrodes and highly flexible polyimide cables for acute neural recording.

PubMed

Kisban, S; Herwik, S; Seidl, K; Rubehn, B; Jezzini, A; Umiltà, M A; Fogassi, L; Stieglitz, T; Paul, O; Ruther, P

2007-01-01

This paper reports on a novel type of silicon-based microprobes with linear, two and three dimensional (3D) distribution of their recording sites. The microprobes comprise either single shafts, combs with multiple shafts or 3D arrays combining two combs with 9, 36 or 72 recording sites, respectively. The electrical interconnection of the probes is achieved through highly flexible polyimide ribbon cables attached using the MicroFlex Technology which allows a connection part of small lateral dimensions. For an improved handling, probes can be secured by a protecting canula. Low-impedance electrodes are achieved by the deposition of platinum black. First in vivo experiments proved the capability to record single action potentials in the motor cortex from electrodes close to the tip as well as body electrodes along the shaft.

Two multichannel integrated circuits for neural recording and signal processing.

PubMed

Obeid, Iyad; Morizio, James C; Moxon, Karen A; Nicolelis, Miguel A L; Wolf, Patrick D

2003-02-01

We have developed, manufactured, and tested two analog CMOS integrated circuit "neurochips" for recording from arrays of densely packed neural electrodes. Device A is a 16-channel buffer consisting of parallel noninverting amplifiers with a gain of 2 V/V. Device B is a 16-channel two-stage analog signal processor with differential amplification and high-pass filtering. It features selectable gains of 250 and 500 V/V as well as reference channel selection. The resulting amplifiers on Device A had a mean gain of 1.99 V/V with an equivalent input noise of 10 microV(rms). Those on Device B had mean gains of 53.4 and 47.4 dB with a high-pass filter pole at 211 Hz and an equivalent input noise of 4.4 microV(rms). Both devices were tested in vivo with electrode arrays implanted in the somatosensory cortex.

Microfabricated electrospray emitter arrays with integrated extractor and accelerator electrodes for the propulsion of small spacecraft

NASA Astrophysics Data System (ADS)

Dandavino, S.; Ataman, C.; Ryan, C. N.; Chakraborty, S.; Courtney, D.; Stark, J. P. W.; Shea, H.

2014-07-01

Microfabricated electrospray thrusters could revolutionize the spacecraft industry by providing efficient propulsion capabilities to micro and nano satellites (1-100 kg). We present the modeling, design, fabrication and characterization of a new generation of devices, for the first time integrating in the fabrication process individual accelerator electrodes capable of focusing and accelerating the emitted sprays. Integrating these electrodes is a key milestone in the development of this technology; in addition to increasing the critical performance metrics of thrust, specific impulse and propulsive efficiency, the accelerators enable a number of new system features such as power tuning and thrust vectoring and balancing. Through microfabrication, we produced high density arrays (213 emitters cm-2) of capillary emitters, assembling them at wafer-level with an extractor/accelerator electrode pair separated by micro-sandblasted glass. Through IV measurements, we could confirm that acceleration could be decoupled from the extraction of the spray—an important element towards the flexibility of this technology. We present the largest reported internally fed microfabricated arrays operation, with 127 emitters spraying in parallel, for a total beam of 10-30 µA composed by 95% of ions. Effective beam focusing was also demonstrated, with plume half-angles being reduced from approximately 30° to 15° with 2000 V acceleration. Based on these results, we predict, with 3000 V acceleration, thrust per emitter of 38.4 nN, specific impulse of 1103 s and a propulsive efficiency of 22% with <1 mW/emitter power consumption.

OH radical production in an atmospheric pressure surface micro-discharge array

NASA Astrophysics Data System (ADS)

Li, D.; Nikiforov, A.; Britun, N.; Snyders, R.; Kong, M. G.; Leys, C.

2016-11-01

The generation of OH radicals from an array of surface micro-discharges working in atmospheric pressure He/Ar/H2O mixtures is investigated. The absolute OH density and its temporal-and-spatial dynamics are detected by UV broadband absorption spectroscopy (UV-BAS) and laser-induced fluorescence (LIF) spectroscopy. The measured absolute density of OH(X) state is about 1021 m-3 in Ar/H2O mixture reaching a peak at 0.05% of H2O. In the case of He/H2O mixtures however, the peaking at ~1019 m-3 is approximately two orders of magnitude lower and decreases monotonously with increasing H2O content. From a control standpoint, the ratio of the Ar/He mixture may be adjusted to tune the OH density over two orders of magnitude and to modulate the H2O content dependence of the OH density. The capability of modulating the OH radical production over a large density range is of practical interest for many applications such as atmospheric chemistry and biochemistry. With the array of atmospheric micro-discharges sustained over a large electrode area, a uniform distribution of its OH density can be achieved in a plane parallel to the electrodes thus enabling spatially controlled surface treatment of large samples.

[Finite element analysis of temperature field of retina by electrical stimulation with microelectrode array].

PubMed

Wang, Wei; Qiao, Qingli; Gao, Weiping; Wu, Jun

2014-12-01

We studied the influence of electrode array parameters on temperature distribution to the retina during the use of retinal prosthesis in order to avoid thermal damage to retina caused by long-term electrical stimulation. Based on real epiretinal prosthesis, a three-dimensional model of electrical stimulation for retina with 4 X 4 microelectrode array had been established using the finite element software (COMSOL Multiphysics). The steady-state temperature field of electrical stimulation of the retina was calculated, and the effects of the electrode parameters such as the distance between the electrode contacts, the materials and area of the electrode contact on temperature field were considered. The maximum increase in the retina steady temperature was about 0. 004 degrees C with practical stimulation current. When the distance between the electrode contacts was changed from 130 microm to 520 microm, the temperature was reduced by about 0.006 microC. When the contact radius was doubled from 130 microm to 260 microm, the temperature decrease was about 0.005 degrees C. It was shown that there were little temperature changes in the retina with a 4 x 4 epiretinal microelectrode array, reflecting the safety of electrical stimulation. It was also shown that the maximum temperature in the retina decreased with increasing the distance between the electrode contacts, as well as increasing the area of electrode contact. However, the change of the maximum temperature was very small when the distance became larger than the diameter of electrode contact. There was no significant difference in the effects of temperature increase among the different electrode materials. Rational selection of the distance between the electrode contacts and their area in electrode design can reduce the temperature rise induced by electrical stimulation.

Arrays of EAP micro-actuators for single-cell stretching applications

NASA Astrophysics Data System (ADS)

Akbari, S.; Niklaus, M.; Shea, H.

2010-04-01

Mechanical stimuli are critical for the development and maintenance of most tissues such as muscles, cartilage, bones and blood vessels. The commercially available cell culture systems replicating the in vivo environment are typically based on simple membrane cell-stretching equipment, which can only measure the average response of large colonies of cells over areas of greater than one cm2. We present here the conceptual design and the complete fabrication process of an array of 128 Electro-Active Polymer (EAP) micro-actuators which are uni-axially stretched and hence used to impose unidirectional strain on single cells, make it feasible to do experiments on the cytomechanics of individual cells. The Finite Element Method is employed to study the effect of different design parameters on achievable strain, leading to the optimized design. Compliant gold electrodes are deposited by low-energy ion implantation on both sides of a PDMS membrane, as this technique allows making electrodes that support large strain with minimal stiffening of the elastomer. The membrane is bonded to a rigid support, leading to an array of 100×100 μm2 EAP actuators.

Autonomous colloidal crystallization in a galvanic microreactor

NASA Astrophysics Data System (ADS)

Punckt, Christian; Jan, Linda; Jiang, Peng; Frewen, Thomas A.; Saville, Dudley A.; Kevrekidis, Ioannis G.; Aksay, Ilhan A.

2012-10-01

We report on a technique that utilizes an array of galvanic microreactors to guide the assembly of two-dimensional colloidal crystals with spatial and orientational order. Our system is comprised of an array of copper and gold electrodes in a coplanar arrangement, immersed in a dilute hydrochloric acid solution in which colloidal micro-spheres of polystyrene and silica are suspended. Under optimized conditions, two-dimensional colloidal crystals form at the anodic copper with patterns and crystal orientation governed by the electrode geometry. After the aggregation process, the colloidal particles are cemented to the substrate by co-deposition of reaction products. As we vary the electrode geometry, the dissolution rate of the copper electrodes is altered. This way, we control the colloidal motion as well as the degree of reaction product formation. We show that particle motion is governed by a combination of electrokinetic effects acting directly on the colloidal particles and bulk electrolyte flow generated at the copper-gold interface.

From macro- to micro-single chamber solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Buergler, B. E.; Ochsner, M.; Vuillemin, S.; Gauckler, L. J.

Single chamber solid oxide fuel cells (SC-SOFCs) with interdigitating electrodes were prepared and operated in CH 4/air mixtures. Both electrodes (Ni-Ce 0.8Gd 0.2O 1.9 cermet and Sm 0.5Sr 0.5CoO 3- δ perovskite) were placed on the same side of a Ce 0.8Gd 0.1O 1.95 electrolyte disc. The separating gap between the electrodes was varied from 1.2 to 0.27 mm and finally down to 10 μm. Screen-printing was used for the preparation of the cells with a gap in the millimetre range, whereas micromolding in capillaries (MIMIC) was used for the preparation of the micro-SC-SOFCs. The prepared micro-SC-SOFCs consisted of an array of 19 individual cells that were connected in parallel having 100 μm wide electrodes. An open circuit voltage of 0.65-0.75 V was measured in flowing mixtures of methane and air. The maximum power density of 17 mW cm -2 was limited by the ohmic resistance of the long conduction paths along the thin electrodes to the active sites of the individual cells. The feasibility of the micro-cell was demonstrated by comparing the performance with the performance of the cells having feature sizes in the millimetre range. The cell resistance of micro-SC-SOFCs may be significantly reduced when connecting the cells in series using interconnections between anode and cathodes of adjacent cells.

Fabrication and characterization of microsieve electrode array (µSEA) enabling cell positioning on 3D electrodes

NASA Astrophysics Data System (ADS)

Schurink, B.; Tiggelaar, R. M.; Gardeniers, J. G. E.; Luttge, R.

2017-01-01

Here the fabrication and characterization of a novel microelectrode array for electrophysiology applications is described, termed a micro sieve electrode array (µSEA). This silicon based µSEA device allows for hydrodynamic parallel positioning of single cells on 3D electrodes realized on the walls of inverted pyramidal shaped pores. To realize the µSEA, a previously realized silicon sieving structure is provided with a patterned boron doped poly-silicon, connecting the contact electrodes with the 3D sensing electrodes in the pores. A LPCVD silicon-rich silicon nitride layer was used as insulation. The selective opening of this insulation layer at the ends of the wiring lines allows to generate well-defined contact and sensing electrodes according to the layout used in commercial microelectrode array readers. The main challenge lays in the simultaneously selective etching of material at both the planar surface (contact electrode) as well as in the sieving structure containing the (3D) pores (sensing electrodes). For the generation of 3D electrodes in the pores a self-aligning technique was developed using the pore geometry to our advantage. This technique, based on sacrificial layer etching, allows for the fine tuning of the sensing electrode surface area and thus supports the positioning and coupling of single cells on the electrode surface in relation to the cell size. Furthermore, a self-aligning silicide is formed on the sensing electrodes to favour the electrical properties. Experiments were performed to demonstrate the working principle of the µSEA using different types of neuronal cells. Capture efficiency in the pores was  >70% with a 70% survival rate of the cell maintained for up to 14 DIV. The TiSi2-boron-doped-poly-silicon sensing electrodes of the µSEA were characterized, which indicated noise levels of  <15 µV and impedance values of 360 kΩ. These findings potentially allow for future electrophysiological measurements using the µSEA.

Caged Neuron MEA: A system for long-term investigation of cultured neural network connectivity

PubMed Central

Erickson, Jonathan; Tooker, Angela; Tai, Y-C.; Pine, Jerome

2008-01-01

Traditional techniques for investigating cultured neural networks, such as the patch clamp and multi-electrode array, are limited by: 1) the number of identified cells which can be simultaneously electrically contacted, 2) the length of time for which cells can be studied, and 3) the lack of one-to-one neuron-to-electrode specificity. Here, we present a new device—the caged neuron multi-electrode array—which overcomes these limitations. This micro-machined device consists of an array of neurocages which mechanically trap a neuron near an extracellular electrode. While the cell body is trapped, the axon and dendrites can freely grow into the surrounding area to form a network. The electrode is bi-directional, capable of both stimulating and recording action potentials. This system is non-invasive, so that all constituent neurons of a network can be studied over its lifetime with stable one-to-one neuron-to-electrode correspondence. Proof-of-concept experiments are described to illustrate that functional networks form in a neurochip system of 16 cages in a 4×4 array, and that suprathreshold connectivity can be fully mapped over several weeks. The neurochip opens a new domain in neurobiology for studying small cultured neural networks. PMID:18775453

A novel piezoelectric quartz micro-array immunosensor for detection of immunoglobulinE.

PubMed

Yao, Chunyan; Chen, Qinghai; Chen, Ming; Zhang, Bo; Luo, Yang; Huang, Qing; Huang, Junfu; Fu, Weiling

2006-12-01

A novel multi-channel 2 x 5 model of piezoelectric (PZ) micro-array immunosensor has been developed for quantitative detection of human immunoglobulinE (IgE) in serum. Every crystal unit of the fabricated piezoelectric IgE micro-array immunosensor can oscillate without interfering each other. A multi-channel 2 x 5 model micro-array immunosensor as compared with the traditional one-channel immunosensor can provide eight times higher detection speeds for IgE assay. The anti-IgE antibody is deposited on the gold electrode's surface of 10 MHz AT-cut quartz crystals by SPA (staphylococcal protein A), and serves as an antibody recognizing layer. The highly ordered antibody monolayers ensure well-controlled surface structure and offer many advantages to the performance of the sensor. The uniform amount of antibody monolayer coated by the SPA is good, and non-specific reaction caused by other immunoglobulin in sample is found. The fabricated PZ immunosensor can be used for human IgE determination in the range of 5-300 IU/ml with high precision (CV is 4%). 50 human serum samples were detected by the micro-array immunosensor, and the results agreed well with those given by the commercially ELISA test kits. The correlation coefficient is 0.94 between ELISA and PZ immunosensor. After regeneration with NaOH the coated immunosensor can be reused 6 times without appreciable loss of activity.

The use of optical fiber bundles combined with electrochemistry for chemical imaging.

PubMed

Szunerits, Sabine; Walt, David R

2003-02-17

The present Review describes the progress made in using imaging optical fiber bundles for fluorescence and electrochemical-initiated chemiluminescence imaging. A novel optoelectrochemical micro-ring array has been fabricated and demonstrated for concurrent electrochemical and optical measurements. The device comprises optical fibers coated with gold via electroless gold deposition and assembled in a random array format. The design yielded an array of approximately 200 micro-ring electrodes, where interdiffusional problems were minimized. The inner diameter of the ring electrode is fixed by the diameter of the individual optical fibers (25 microns), while the outer radius is determined by the thickness of the deposited gold. While all the fibers are optically addressable, they are not all electrochemically addressable. The resolution of this device is in the tens of micrometers range, determined by the diameter of the optical fiber (25 microns) and by the spacing between each electrically connected fiber. For the purpose of having well-behaved microelectrode characteristics, this spacing was designed to be larger than 60 microns. The array was characterized using ferrocyanide in aqueous solution as a model electroactive species to demonstrate that this microelectrode array format exhibits steady-state currents at short response times. This device has potential application to be used as an optoelectronic sensor, especially for the electrolytic generation and transmission of electrochemiluminescence, and was used to demonstrate that electrochemically generated luminescent products can be detected with the fiber assembly.

An implantable integrated low-power amplifier-microelectrode array for Brain-Machine Interfaces.

PubMed

Patrick, Erin; Sankar, Viswanath; Rowe, William; Sanchez, Justin C; Nishida, Toshikazu

2010-01-01

One of the important challenges in designing Brain-Machine Interfaces (BMI) is to build implantable systems that have the ability to reliably process the activity of large ensembles of cortical neurons. In this paper, we report the design, fabrication, and testing of a polyimide-based microelectrode array integrated with a low-power amplifier as part of the Florida Wireless Integrated Recording Electrode (FWIRE) project at the University of Florida developing a fully implantable neural recording system for BMI applications. The electrode array was fabricated using planar micromachining MEMS processes and hybrid packaged with the amplifier die using a flip-chip bonding technique. The system was tested both on bench and in-vivo. Acute and chronic neural recordings were obtained from a rodent for a period of 42 days. The electrode-amplifier performance was analyzed over the chronic recording period with the observation of a noise floor of 4.5 microVrms, and an average signal-to-noise ratio of 3.8.

Quantitative measurements of ground state atomic oxygen in atmospheric pressure surface micro-discharge array

NASA Astrophysics Data System (ADS)

Li, D.; Kong, M. G.; Britun, N.; Snyders, R.; Leys, C.; Nikiforov, A.

2017-06-01

The generation of atomic oxygen in an array of surface micro-discharge, working in atmospheric pressure He/O2 or Ar/O2 mixtures, is investigated. The absolute atomic oxygen density and its temporal and spatial dynamics are studied by means of two-photon absorption laser-induced fluorescence. A high density of atomic oxygen is detected in the He/O2 mixture with up to 10% O2 content in the feed gas, whereas the atomic oxygen concentration in the Ar/O2 mixture stays below the detection limit of 1013 cm-3. The measured O density near the electrode under the optimal conditions in He/1.75% O2 gas is 4.26  ×  1015 cm-3. The existence of the ground state O (2p 4 3 P) species has been proven in the discharge at a distance up to 12 mm away from the electrodes. Dissociative reactions of the singlet O2 with O3 and deep vacuum ultraviolet radiation, including the radiation of excimer \\text{He}2\\ast , are proposed to be responsible for O (2p 4 3 P) production in the far afterglow. A capability of the surface micro-discharge array delivering atomic oxygen to long distances over a large area is considered very interesting for various biomedical applications.

Micro-hole array fluorescent sensor based on AC-Dielectrophoresis (DEP) for simultaneous analysis of nano-molecules

NASA Astrophysics Data System (ADS)

Kim, Hye Jin; Kang, Dong-Hoon; Lee, Eunji; Hwang, Kyo Seon; Shin, Hyun-Joon; Kim, Jinsik

2018-02-01

We propose a simple fluorescent bio-chip based on two types of alternative current-dielectrophoretic (AC-DEP) force, attractive (positive DEP) and repulsive (negative DEP) force, for simultaneous nano-molecules analysis. Various radius of micro-holes on the bio-chip are designed to apply the different AC-DEP forces, and the nano-molecules are concentrated inside the micro-hole arrays according to the intensity of the DEP force. The bio-chip was fabricated by Micro Electro Mechanical system (MEMS) technique, and was composed of two layers; a SiO2 layer and Ta/Pt layer were accomplished for an insulation layer and a top electrode with micro-hole arrays to apply electric fields for DEP force, respectively. Each SiO2 and Ta/Pt layers were deposited by thermal oxidation and sputtering, and micro-hole arrays were fabricated with Inductively Coupled Plasma (ICP) etching process. For generation of each positive and negative DEP at micro-holes, we applied two types of sine-wave AC voltage with different frequency range alternately. The intensity of the DEP force was controlled by the radius of the micro-hole and size of nano-molecule, and calculated with COMSOL multi-physics. Three types of nano-molecules labelled with different fluorescent dye were used and the intensity of nano-molecules was examined by the fluorescent optical analysis after applying the DEP force. By analyzing the fluorescent intensities of the nano-molecules, we verify the various nano-molecules in analyte are located successfully inside corresponding micro-holes with different radius according to their size.

Improvement of the electrochemical properties via poly(3,4-ethylenedioxythiophene) oriented micro/nanorods

NASA Astrophysics Data System (ADS)

Li, Yu; Wang, Bichen; Chen, Huimin; Feng, Wei

Arrays of oriented poly(3,4-ethylenedioxythiophene) (PEDOT) micro/nanorods are synthesized by electrochemical galvanostatic method at the current density of 1 mA cm -2 in the cetyltrimethylammonium bromide (CTAB) aqueous solution whose pH value is 1. The CTAB is used both as the surfactant and the supporting salt in the electrolyte solution. The electrochemical properties of PEDOT films are characterized by cyclic voltammetry and galvanostatic charge/discharge techniques, which indicate that the arrays of oriented PEDOT micro/nanorods can be applied as the electrode materials of supercapacitors. In addition, the cycling performance of PEDOT micro/nanorods is much better than that of traditional PEDOT particles. The effects of the concentration of CTAB, the current density, and pH value of electrolyte solutions on the morphologies and electrochemical properties of PEDOT films are investigated. The mechanism of different morphologies formation is discussed in this study as well.

Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties.

PubMed

Guan, Dongsheng; Cai, Chuan; Wang, Ying

2011-04-01

We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.

Activation and control of microlens liquid arrays on functionalized polar electric crystal substrates by electro-wetting effect and temperature

NASA Astrophysics Data System (ADS)

Ferraro, Pietro; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Finizio, Sergio DeNicola Andrea

2008-11-01

In recent years a variety of liquid bases optical elements have been conceived, designed and fabricated even for commercial products like digital cameras o cellular phone cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new Science field of investigation named optofludics. Optofludics, among others topics, deals with investigation and methods for realizing liquid micro-lenses. A variety of liquid micro-lenses have been designed and realized by using different configurations. We demonstrate that a lensing effect can be obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal such as Lithium Niobate (LiNbO3). Electrowetting patterning on LiNbO3 surface is obtained by pyroelectric effect consisting in a simple but reliable electrodes-less and circuit-less configuration. The electrodes are intrinsically embedded into the substrate. The material is functionalised by means of a micro-engineering electric filed poling process. Lens array with variable focus has been demonstrated with a large number of lens elements (10x10) on micrometric scale (aperture of single lens 100 microns).

A Microelectrode Array with Reproducible Performance Shows Loss of Consistency Following Functionalization with a Self-Assembled 6-Mercapto-1-hexanol Layer.

PubMed

Corrigan, Damion K; Vezza, Vincent; Schulze, Holger; Bachmann, Till T; Mount, Andrew R; Walton, Anthony J; Terry, Jonathan G

2018-06-09

For analytical applications involving label-free biosensors and multiple measurements, i.e., across an electrode array, it is essential to develop complete sensor systems capable of functionalization and of producing highly consistent responses. To achieve this, a multi-microelectrode device bearing twenty-four equivalent 50 µm diameter Pt disc microelectrodes was designed in an integrated 3-electrode system configuration and then fabricated. Cyclic voltammetry and electrochemical impedance spectroscopy were used for initial electrochemical characterization of the individual working electrodes. These confirmed the expected consistency of performance with a high degree of measurement reproducibility for each microelectrode across the array. With the aim of assessing the potential for production of an enhanced multi-electrode sensor for biomedical use, the working electrodes were then functionalized with 6-mercapto-1-hexanol (MCH). This is a well-known and commonly employed surface modification process, which involves the same principles of thiol attachment chemistry and self-assembled monolayer (SAM) formation commonly employed in the functionalization of electrodes and the formation of biosensors. Following this SAM formation, the reproducibility of the observed electrochemical signal between electrodes was seen to decrease markedly, compromising the ability to achieve consistent analytical measurements from the sensor array following this relatively simple and well-established surface modification. To successfully and consistently functionalize the sensors, it was necessary to dilute the constituent molecules by a factor of ten thousand to support adequate SAM formation on microelectrodes. The use of this multi-electrode device therefore demonstrates in a high throughput manner irreproducibility in the SAM formation process at the higher concentration, even though these electrodes are apparently functionalized simultaneously in the same film formation environment, confirming that the often seen significant electrode-to-electrode variation in label-free SAM biosensing films formed under such conditions is not likely to be due to variation in film deposition conditions, but rather kinetically controlled variation in the SAM layer formation process at these microelectrodes.

Large-sized out-of-plane stretchable electrodes based on poly-dimethylsiloxane substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chou, Namsun; Lee, Jongho; Research Institute for Solar and Sustainable Energies

2014-12-15

This paper describes a reliable fabrication method of stretchable electrodes based on poly-dimethylsiloxane (PDMS) substrate. The electrode traces and pads were formed in out-of-plane structures to improve the flexibility and stretchability of the electrode array. The suspended traces and pads were attached to the PDMS substrate via parylene posts that were located nearby the traces and under the pads. As only conventional micro-electro-mechanical systems techniques were used, the out-of-plane electrode arrays were clearly fabricated at wafer level with high yield and reliability. Also, bi-layer out-of-plane electrodes were formed through additional fabrication steps in addition to mono-layer out-of-plane electrodes. The mechanicalmore » characteristics such as the stretchability, flexibility, and foldability of the fabricated electrodes were evaluated, resulting in stable electrical connection of the metal traces with up to 32.4% strain and up to 360° twist angle over 25 mm. The durability in stretched condition was validated by cyclic stretch test with 10% and 20% strain, resulting in electrical disconnection at 8600 cycles when subjected to 20% strain. From these results, it is concluded that the proposed fabrication method produced highly reliable, out-of-plane and stretchable electrodes, which would be used in various flexible and stretchable electronics applications.« less

Development of micro-electrode array based tests for neurotoxicity: assessment of interlaboratory reproducibility with neuroactive chemicals

EPA Science Inventory

Neuronal assemblies within the Central Nervous System (CNS) produce spontaneous or stimulus-evoked electrophysiological activity that can be monitored and quantified in terms of action potential patterns. Such patterns provide a sensitive endpoint to detect effects of chemicals, ...

Electrochemical characteristics of flexible micro supercapacitors with reduced graphene oxide-carbon nanotubes composite electrodes

NASA Astrophysics Data System (ADS)

Yang, Kyungwhan; Cho, Kyoungah; Kim, Sangsig

2018-06-01

In this study, we fabricate solid-state flexible micro-supercapacitors (MSCs) with reduced graphene oxide-carbon nanotube (rGO-CNT) composite electrodes and investigate the electrochemical characteristics by comparing with those of an MSC with rGO electrodes. Regarding the resistance-capacitance time constant and IR drop, the addition of CNTs into the rGO electrodes shows a significant effect owing to both the decrease in the resistance and the increase in the permeability of the electrolytes. Compared to the rGO MSCs, the rGO-CNT MSCs show an excellent areal capacitance of 2.6 mF/cm2, a smaller IR drop of 11 mV, a lower RC time constant of 6 ms, and faster charging/discharging rates with a high scan rate ability up to 100 V/s. The mechanical stability of the flexible rGO-CNT MSCs is verified by 1000 bending cycles. In addition, the electrochemical characteristics of the flexible rGO-CNT MSCs are maintained regardless of the MSC array type.

3D hierarchical assembly of ultrathin MnO2 nanoflakes on silicon nanowires for high performance micro-supercapacitors in Li- doped ionic liquid

PubMed Central

Dubal, Deepak P.; Aradilla, David; Bidan, Gérard; Gentile, Pascal; Schubert, Thomas J.S.; Wimberg, Jan; Sadki, Saïd; Gomez-Romero, Pedro

2015-01-01

Building of hierarchical core-shell hetero-structures is currently the subject of intensive research in the electrochemical field owing to its potential for making improved electrodes for high-performance micro-supercapacitors. Here we report a novel architecture design of hierarchical MnO2@silicon nanowires (MnO2@SiNWs) hetero-structures directly supported onto silicon wafer coupled with Li-ion doped 1-Methyl-1-propylpyrrolidinium bis(trifluromethylsulfonyl)imide (PMPyrrBTA) ionic liquids as electrolyte for micro-supercapacitors. A unique 3D mesoporous MnO2@SiNWs in Li-ion doped IL electrolyte can be cycled reversibly across a voltage of 2.2 V and exhibits a high areal capacitance of 13 mFcm−2. The high conductivity of the SiNWs arrays combined with the large surface area of ultrathin MnO2 nanoflakes are responsible for the remarkable performance of these MnO2@SiNWs hetero-structures which exhibit high energy density and excellent cycling stability. This combination of hybrid electrode and hybrid electrolyte opens up a novel avenue to design electrode materials for high-performance micro-supercapacitors. PMID:25985388

An Integrated Ignition and Combustion System for Liquid Propellant Micro Propulsion

DTIC Science & Technology

2008-06-26

using a microfin electrode array. They demonstrated successful gasification and ignition of the liquid propellant using this concept. The concept has...Transition to Detonation of Stoichiometric Ethylene/Oxygen in Microscale Tubes (with M-H. Wu, M.P. Burke, and S.F. Son) Proceedings of the

Vertically Aligned Niobium Nanowire Arrays for Fast-Charging Micro-Supercapacitors.

PubMed

Mirvakili, Seyed M; Hunter, Ian W

2017-07-01

Planar micro-supercapacitors are attractive for system on chip technologies and surface mount devices due to their large areal capacitance and energy/power density compared to the traditional oxide-based capacitors. In the present work, a novel material, niobium nanowires, in form of vertically aligned electrodes for application in high performance planar micro-supercapacitors is introduced. Specific capacitance of up to 1 kF m -2 (100 mF cm -2 ) with peak energy and power density of 2 kJ m -2 (6.2 MJ m -3 or 1.7 mWh cm -3 ) and 150 kW m -2 (480 MW m -3 or 480 W cm -3 ), respectively, is achieved. This remarkable power density, originating from the extremely low equivalent series resistance value of 0.27 Ω (2.49 µΩ m 2 or 24.9 mΩ cm 2 ) and large specific capacitance, is among the highest for planar micro-supercapacitors electrodes made of nanomaterials. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using Arrays of Microelectrodes Implanted in Residual Peripheral Nerves to Provide Dexterous Control of, and Modulated Sensory Feedback from, a Hand Prosthesis

DTIC Science & Technology

2016-10-01

isolated action potentials or multi-action potential activity from residual peripheral nerve while patient intends movements of amputated hand/arm...Subtask 3.1: Mapping of neural activity (Months 4 – 36) • Patients will be asked to intend a number of individual finger and multiple finger flexion...during these intended movements. We will map the different intended movements onto the neural activity recorded on the electrodes of the micro-electrode

Nanoengineering of 2D tin sulfide nanoflake arrays incorporated on polyaniline nanofibers with boosted capacitive behavior

NASA Astrophysics Data System (ADS)

Wang, Huanhuan; Chao, DongLiang; Liu, Jilei; Lin, Jianyi; Shen, Ze Xiang

2018-07-01

Nanoscale engineering plays an important role in designing novel electrode architecture and boosting energy storage in supercapacitors. Herein, we demonstrate the fabrication of freestanding tin sulfide based supercapacitor electrode using facile nucleation substrate control, i.e. polyaniline network. This is the first time that tin sulfide based material is fabricated as a binder-free electrode for supercapacitors. The first combination of tin sulfide and polyaniline also evokes synergistic effect to enhance the performance as the polyaniline nanofibers facilitate the growth of tin sulfide flakes in nanosize which is further proved helpful for improving the capacity and stability of the electrode. The as-obtained electrode of tin sulfide nanoflake arrays incorporated on polyaniline nanofibers (365 F g‑1 at 10 mV s‑1) exhibits superior electrochemical performance compared with micro-scaled tin sulfide (32 F g‑1 at 10 mV s‑1). The significantly improved pseudocapacitive and diffusive contributions of polyaniline nanofibers incorporated electrode are identified by quantitative kinetics analysis due to greatly decreased particle size and introduced mesopores, nanoclusters, and exposed edges. Profited from effective nanostructure engineering, a Na+ intercalation mechanism is also pointed out in boosting the electrochemical performance.

Biomimetic hydrogels for biosensor implant biocompatibility: electrochemical characterization using micro-disc electrode arrays (MDEAs).

PubMed

Justin, Gusphyl; Finley, Stephen; Abdur Rahman, Abdur Rub; Guiseppi-Elie, Anthony

2009-02-01

Our interest is in the development of engineered microdevices for continuous remote monitoring of intramuscular lactate, glucose, pH and temperature during post-traumatic hemorrhaging. Two important design considerations in the development of such devices for in vivo diagnostics are discussed; the utility of micro-disc electrode arrays (MDEAs) for electrochemical biosensing and the application of biomimetic, bioactive poly(HEMA)-based hydrogel composites for implant biocompatibility. A poly(HEMA)-based hydrogel membrane containing polyethylene glycol (PEG) was UV cross-linked with tetraethyleneglycol diacrylate following application to MDEAs (50 mum discs) and to 250 mum diameter gold electrodes within 8-well culture ware. Cyclic voltammetry (CV) of the MDEAs revealed a reduction in the apparent diffusion coefficient of ferrocenemonocarboxylic acid (FcCO(2)H), from 6.68 x 10(-5) to 6.74 x 10(-6) cm(2)/s for the uncoated and 6 mum thick hydrogel coated devices, respectively. Single frequency (4 kHz) temporal impedance measurements of the hydrogels in the 8-well culture ware showed a reversible 5% change in the absolute impedance of the hydrogels when exposed to a pH change between 6.1 to 7.2 and a 20% drop between pH 6.1 and 8.8.

Development of an IrO x micro pH sensor array on flexible polymer substrate

NASA Astrophysics Data System (ADS)

Huang, Wen-Ding; Wang, Jianqun; Ativanichayaphong, Thermpon; Chiao, Mu; Chiao, J. C.

2008-03-01

pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages in specific applications. It is difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to size limitation and no deformability. In this paper, we present design and fabrication processes of a miniature iridium oxide thin film pH sensor array on flexible polymer substrates. The amorphous iridium oxide thin film was used as the sensing material. A sol-gel dip-coating process of iridium oxide film was demonstrated in this paper. A super-Nernstian response has been measured on individual sensors of the array with a slope of -71.6+/-3 mV/pH at 25°C within the pH range between 2.83 and 11.04.

High Spatiotemporal Resolution ECoG Recording of Somatosensory Evoked Potentials with Flexible Micro-Electrode Arrays.

PubMed

Kaiju, Taro; Doi, Keiichi; Yokota, Masashi; Watanabe, Kei; Inoue, Masato; Ando, Hiroshi; Takahashi, Kazutaka; Yoshida, Fumiaki; Hirata, Masayuki; Suzuki, Takafumi

2017-01-01

Electrocorticogram (ECoG) has great potential as a source signal, especially for clinical BMI. Until recently, ECoG electrodes were commonly used for identifying epileptogenic foci in clinical situations, and such electrodes were low-density and large. Increasing the number and density of recording channels could enable the collection of richer motor/sensory information, and may enhance the precision of decoding and increase opportunities for controlling external devices. Several reports have aimed to increase the number and density of channels. However, few studies have discussed the actual validity of high-density ECoG arrays. In this study, we developed novel high-density flexible ECoG arrays and conducted decoding analyses with monkey somatosensory evoked potentials (SEPs). Using MEMS technology, we made 96-channel Parylene electrode arrays with an inter-electrode distance of 700 μm and recording site area of 350 μm 2 . The arrays were mainly placed onto the finger representation area in the somatosensory cortex of the macaque, and partially inserted into the central sulcus. With electrical finger stimulation, we successfully recorded and visualized finger SEPs with a high spatiotemporal resolution. We conducted offline analyses in which the stimulated fingers and intensity were predicted from recorded SEPs using a support vector machine. We obtained the following results: (1) Very high accuracy (~98%) was achieved with just a short segment of data (~15 ms from stimulus onset). (2) High accuracy (~96%) was achieved even when only a single channel was used. This result indicated placement optimality for decoding. (3) Higher channel counts generally improved prediction accuracy, but the efficacy was small for predictions with feature vectors that included time-series information. These results suggest that ECoG signals with high spatiotemporal resolution could enable greater decoding precision or external device control.

High Spatiotemporal Resolution ECoG Recording of Somatosensory Evoked Potentials with Flexible Micro-Electrode Arrays

PubMed Central

Kaiju, Taro; Doi, Keiichi; Yokota, Masashi; Watanabe, Kei; Inoue, Masato; Ando, Hiroshi; Takahashi, Kazutaka; Yoshida, Fumiaki; Hirata, Masayuki; Suzuki, Takafumi

2017-01-01

Electrocorticogram (ECoG) has great potential as a source signal, especially for clinical BMI. Until recently, ECoG electrodes were commonly used for identifying epileptogenic foci in clinical situations, and such electrodes were low-density and large. Increasing the number and density of recording channels could enable the collection of richer motor/sensory information, and may enhance the precision of decoding and increase opportunities for controlling external devices. Several reports have aimed to increase the number and density of channels. However, few studies have discussed the actual validity of high-density ECoG arrays. In this study, we developed novel high-density flexible ECoG arrays and conducted decoding analyses with monkey somatosensory evoked potentials (SEPs). Using MEMS technology, we made 96-channel Parylene electrode arrays with an inter-electrode distance of 700 μm and recording site area of 350 μm2. The arrays were mainly placed onto the finger representation area in the somatosensory cortex of the macaque, and partially inserted into the central sulcus. With electrical finger stimulation, we successfully recorded and visualized finger SEPs with a high spatiotemporal resolution. We conducted offline analyses in which the stimulated fingers and intensity were predicted from recorded SEPs using a support vector machine. We obtained the following results: (1) Very high accuracy (~98%) was achieved with just a short segment of data (~15 ms from stimulus onset). (2) High accuracy (~96%) was achieved even when only a single channel was used. This result indicated placement optimality for decoding. (3) Higher channel counts generally improved prediction accuracy, but the efficacy was small for predictions with feature vectors that included time-series information. These results suggest that ECoG signals with high spatiotemporal resolution could enable greater decoding precision or external device control. PMID:28442997

Conducting polymer nanowire arrays for high performance supercapacitors.

PubMed

Wang, Kai; Wu, Haiping; Meng, Yuena; Wei, Zhixiang

2014-01-15

This Review provides a brief summary of the most recent research developments in the fabrication and application of one-dimensional ordered conducting polymers nanostructure (especially nanowire arrays) and their composites as electrodes for supercapacitors. By controlling the nucleation and growth process of polymerization, aligned conducting polymer nanowire arrays and their composites with nano-carbon materials can be prepared by employing in situ chemical polymerization or electrochemical polymerization without a template. This kind of nanostructure (such as polypyrrole and polyaniline nanowire arrays) possesses high capacitance, superior rate capability ascribed to large electrochemical surface, and an optimal ion diffusion path in the ordered nanowire structure, which is proved to be an ideal electrode material for high performance supercapacitors. Furthermore, flexible, micro-scale, threadlike, and multifunctional supercapacitors are introduced based on conducting polyaniline nanowire arrays and their composites. These prototypes of supercapacitors utilize the high flexibility, good processability, and large capacitance of conducting polymers, which efficiently extend the usage of supercapacitors in various situations, and even for a complicated integration system of different electronic devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Highly Stable Glassy Carbon Interfaces for Long-Term Neural Stimulation and Low-Noise Recording of Brain Activity

PubMed Central

Vomero, Maria; Castagnola, Elisa; Ciarpella, Francesca; Maggiolini, Emma; Goshi, Noah; Zucchini, Elena; Carli, Stefano; Fadiga, Luciano; Kassegne, Sam; Ricci, Davide

2017-01-01

We report on the superior electrochemical properties, in-vivo performance and long term stability under electrical stimulation of a new electrode material fabricated from lithographically patterned glassy carbon. For a direct comparison with conventional metal electrodes, similar ultra-flexible, micro-electrocorticography (μ-ECoG) arrays with platinum (Pt) or glassy carbon (GC) electrodes were manufactured. The GC microelectrodes have more than 70% wider electrochemical window and 70% higher CTC (charge transfer capacity) than Pt microelectrodes of similar geometry. Moreover, we demonstrate that the GC microelectrodes can withstand at least 5 million pulses at 0.45 mC/cm2 charge density with less than 7.5% impedance change, while the Pt microelectrodes delaminated after 1 million pulses. Additionally, poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was selectively electrodeposited on both sets of devices to specifically reduce their impedances for smaller diameters (<60 μm). We observed that PEDOT-PSS adhered significantly better to GC than Pt, and allowed drastic reduction of electrode size while maintaining same amount of delivered current. The electrode arrays biocompatibility was demonstrated through in-vitro cell viability experiments, while acute in vivo characterization was performed in rats and showed that GC microelectrode arrays recorded somatosensory evoked potentials (SEP) with an almost twice SNR (signal-to-noise ratio) when compared to the Pt ones. PMID:28084398

Preparation of etched tantalum semimicro capacitor stimulation electrodes.

PubMed

Robblee, L S; Kelliher, E M; Langmuir, M E; Vartanian, H; McHardy, J

1983-03-01

The ideal electrode for stimulation of the nervous system is one that will inject charge by purely capacitive processes. One approach is to exploit the type of metal-oxide combination used in electrolytic capacitors, e.g., Ta/Ta2O5. For this purpose, fine tantalum wire (0.25 mm diam) was etched electrolytically at constant current in a methanol solution of NH4Br containing 1.5 wt % H2O. Electrolytic etching produced a conical tip with a length of ca. 0.5 mm and shaft diameters ranging from 0.10 to 0.16 mm. The etched electrodes were anodized to 10 V (vs. SCE) in 0.1 vol % H3PO4. The capacitance values normalized to geometric area of etched electrodes ranged from 0.13 to 0.33 micro F mm-2. Comparison of these values to the capacitance of "smooth" tantalum anodized to 10 V (0.011 micro F mm-2) indicated that the degree of surface enhancement, or etch ratio, was 12-30. The surface roughness was confirmed by scanning electron microscopy studies which revealed an intricate array of irregularly shaped surface projections about 1-2 micrometers wide. The etched electrodes were capable of delivering 0.06-0.1 micro C of charge with 0.1 ms pulses at a pulse repetition rate of 400 Hz when operated at 50% of the anodization voltage. This quantity of charge corresponded to volumetric charge densities of 20-30 micro C mm-3 and area charge densities of 0.55-0.88 micro C mm-2. Charge storage was proportionately higher at higher fractional values of the formation voltage. Leakage currents at 5 V were ca. 2 nA. Neither long-term passive storage (1500 h) nor extended pulsing time (18 h) had a deleterious effect on electrode performance. The trend in electrical stimulation work is toward smaller electrodes. The procedures developed in this study should be particularly well-suited to the fabrication of even smaller electrodes because of the favorable electrical and geometric characteristics of the etched surface.

Tailoring the electrode-electrolyte interface of Solid Oxide Fuel Cells (SOFC) by laser micro-patterning to improve their electrochemical performance

NASA Astrophysics Data System (ADS)

Cebollero, J. A.; Lahoz, R.; Laguna-Bercero, M. A.; Larrea, A.

2017-08-01

Cathode activation polarisation is one of the main contributions to the losses of a Solid Oxide Fuel Cell. To reduce this loss we use a pulsed laser to modify the surface of yttria stabilized zirconia (YSZ) electrolytes to make a corrugated micro-patterning in the mesoscale. The beam of the laser source, 5 ns pulse width and emitting at λ = 532 nm (green region), is computer-controlled to engrave the selected micro-pattern on the electrolyte surface. Several laser scanning procedures and geometries have been tested. Finally, we engrave a square array with 28 μm of lattice parameter and 7 μm in depth on YSZ plates. With these plates we prepare LSM-YSZ/YSZ/LSM-YSZ symmetrical cells (LSM: La1-xSrxMnO3) and determine their activation polarisation by Electrochemical Impedance Spectroscopy (EIS). To get good electrode-electrolyte contact after sintering it is necessary to use pressure-assisted sintering with low loads (about 5 kPa), which do not modify the electrode microstructure. The decrease in polarisation with respect to an unprocessed cell is about 30%. EIS analysis confirms that the reason for this decrease is an improvement in the activation processes at the electrode-electrolyte interface.

Variable thrust/specific-impulse of multiplexed electrospray microthrusters

NASA Astrophysics Data System (ADS)

Lenguito, G.; Fernandez de la Mora, J.; Gomez, A.

We report on the development of a single-propellant ElectroSpray (ES) microthruster able to: (a) cover a wide range of specific impulse (Isp) and thrust at high propulsion efficiency, and (b) provide macroscopic thrust via micro-fabricated emitter arrays. The electrospray is a mature technology for the emission of fast nanodroplets at a propulsive efficiency larger than 50% over the full Isp range. The size of the droplets depends on the propellant flow rate and the physical properties of the electrolyte, especially the electric conductivity. To achieve a useful thrust one needs to multiplex the ES by operating many in parallel, which we achieve via silicon microfabrication of arrays of multiple and identical nozzles. The Multiplexed Electrospray (MES) micro-thruster is composed mainly of two electrodes: a nozzle-array and an extractor electrode, between which the electric field needed to form the ES is established. We tested nozzle arrays with up to 37 capillaries, that are spaced 1mm apart, with ID/OD = 10/30μ m. The capillaries are filled with 2.01μ m silicon dioxide beads to increase the hydraulic impedance and ensure uniform flow rate through the different emitters. A third electrode (accelerator) is mounted downstream the extractor to accelerate the droplets, thereby increasing the microthruster performance. The system is packaged in an alumina casing for electrical insulation and propellant feed. Tests run in a vacuum chamber at a pressure ≤ 10-5 mbar demonstrated reliable operation for several hours with a relatively high beam energy of 7.56kV. The 37-nozzle MES device was tested with the ionic liquid ethylammonium nitrate (EAN), at estimated total flow rates between 1.2 and 14 μ L/h, emitted currents between 14.2 and 23.0 μ A, specific impulse ranging between 710 and 1930s, and thrust ranging between 7.5 and 33 μ N. EAN is well suited to cover a relatively broad range of charge/mass- at an average propulsion efficiency of 66%. With further scale-up to a 600-MES system, the device would be suitable for micro-satellites missions such as attitude control and station keeping.

Time delay and integration array (TDI) using charge transfer device technology. Phase 2, volume 1: Technical

NASA Technical Reports Server (NTRS)

1977-01-01

The 20x9 TDI array was developed to meet the LANDSAT Thematic Mapper Requirements. This array is based upon a self-aligned, transparent gate, buried channel process. The process features: (1) buried channel, four phase, overlapping gate CCD's for high transfer efficiency without fat zero; (2) self-aligned transistors to minimize clock feedthrough and parasitic capacitance; and (3) transparent tin oxide electrode for high quantum efficiency with front surface irradiation. The requirements placed on the array and the performance achieved are summarized. This data is the result of flat field measurements only, no imaging or dynamic target measurements were made during this program. Measurements were performed with two different test stands. The bench test equipment fabricated for this program operated at the 8 micro sec line time and employed simple sampling of the gated MOSFET output video signal. The second stand employed Correlated Doubled Sampling (CDS) and operated at 79.2 micro sec line time.

Effect of surface nano/micro-structuring on the early formation of microbial anodes with Geobacter sulfurreducens: Experimental and theoretical approaches.

PubMed

Champigneux, Pierre; Renault-Sentenac, Cyril; Bourrier, David; Rossi, Carole; Delia, Marie-Line; Bergel, Alain

2018-06-01

Smooth and nano-rough flat gold electrodes were manufactured with controlled Ra of 0.8 and 4.5nm, respectively. Further nano-rough surfaces (Ra 4.5nm) were patterned with arrays of micro-pillars 500μm high. All these electrodes were implemented in pure cultures of Geobacter sulfurreducens, under a constant potential of 0.1V/SCE and with a single addition of acetate 10mM to check the early formation of microbial anodes. The flat smooth electrodes produced an average current density of 0.9A·m -2 . The flat nano-rough electrodes reached 2.5A·m -2 on average, but with a large experimental deviation of ±2.0A·m -2 . This large deviation was due to the erratic colonization of the surface but, when settled on the surface, the cells displayed current density that was directly correlated to the biofilm coverage ratio. The micro-pillars considerably improved the experimental reproducibility by offering the cells a quieter environment, facilitating biofilm development. Current densities of up to 8.5A·m -2 (per projected surface area) were thus reached, in spite of rate limitation due to the mass transport of the buffering species, as demonstrated by numerical modelling. Nano-roughness combined with micro-structuring increased current density by a factor close to 10 with respect to the smooth flat surface. Copyright © 2018 Elsevier B.V. All rights reserved.

Integration of silicon-based neural probes and micro-drive arrays for chronic recording of large populations of neurons in behaving animals

NASA Astrophysics Data System (ADS)

Michon, Frédéric; Aarts, Arno; Holzhammer, Tobias; Ruther, Patrick; Borghs, Gustaaf; McNaughton, Bruce; Kloosterman, Fabian

2016-08-01

Objective. Understanding how neuronal assemblies underlie cognitive function is a fundamental question in system neuroscience. It poses the technical challenge to monitor the activity of populations of neurons, potentially widely separated, in relation to behaviour. In this paper, we present a new system which aims at simultaneously recording from a large population of neurons from multiple separated brain regions in freely behaving animals. Approach. The concept of the new device is to combine the benefits of two existing electrophysiological techniques, i.e. the flexibility and modularity of micro-drive arrays and the high sampling ability of electrode-dense silicon probes. Main results. Newly engineered long bendable silicon probes were integrated into a micro-drive array. The resulting device can carry up to 16 independently movable silicon probes, each carrying 16 recording sites. Populations of neurons were recorded simultaneously in multiple cortical and/or hippocampal sites in two freely behaving implanted rats. Significance. Current approaches to monitor neuronal activity either allow to flexibly record from multiple widely separated brain regions (micro-drive arrays) but with a limited sampling density or to provide denser sampling at the expense of a flexible placement in multiple brain regions (neural probes). By combining these two approaches and their benefits, we present an alternative solution for flexible and simultaneous recordings from widely distributed populations of neurons in freely behaving rats.

Applying a foil queue micro-electrode in micro-EDM to fabricate a 3D micro-structure

NASA Astrophysics Data System (ADS)

Xu, Bin; Guo, Kang; Wu, Xiao-yu; Lei, Jian-guo; Liang, Xiong; Guo, Deng-ji; Ma, Jiang; Cheng, Rong

2018-05-01

Applying a 3D micro-electrode in a micro electrical discharge machining (micro-EDM) can fabricate a 3D micro-structure with an up and down reciprocating method. However, this processing method has some shortcomings, such as a low success rate and a complex process for fabrication of 3D micro-electrodes. By focusing on these shortcomings, this paper proposed a novel 3D micro-EDM process based on the foil queue micro-electrode. Firstly, a 3D micro-electrode was discretized into several foil micro-electrodes and these foil micro-electrodes constituted a foil queue micro-electrode. Then, based on the planned process path, foil micro-electrodes were applied in micro-EDM sequentially and the micro-EDM results of each foil micro-electrode were able to superimpose the 3D micro-structure. However, the step effect will occur on the 3D micro-structure surface, which has an adverse effect on the 3D micro-structure. To tackle this problem, this paper proposes to reduce this adverse effect by rounded corner wear at the end of the foil micro-electrode and studies the impact of machining parameters on rounded corner wear and the step effect on the micro-structure surface. Finally, using a wire cutting voltage of 80 V, a current of 0.5 A and a pulse width modulation ratio of 1:4, the foil queue micro-electrode was fabricated by wire electrical discharge machining. Also, using a pulse width of 100 ns, a pulse interval of 200 ns, a voltage of 100 V and workpiece material of 304# stainless steel, the foil queue micro-electrode was applied in micro-EDM for processing of a 3D micro-structure with hemispherical features, which verified the feasibility of this process.

Bioinspired leaves-on-branchlet hybrid carbon nanostructure for supercapacitors.

PubMed

Xiong, Guoping; He, Pingge; Lyu, Zhipeng; Chen, Tengfei; Huang, Boyun; Chen, Lei; Fisher, Timothy S

2018-02-23

Designing electrodes in a highly ordered structure simultaneously with appropriate orientation, outstanding mechanical robustness, and high electrical conductivity to achieve excellent electrochemical performance remains a daunting challenge. Inspired by the phenomenon in nature that leaves significantly increase exposed tree surface area to absorb carbon dioxide (like ions) from the environments (like electrolyte) for photosynthesis, we report a design of micro-conduits in a bioinspired leaves-on-branchlet structure consisting of carbon nanotube arrays serving as branchlets and graphene petals as leaves for such electrodes. The hierarchical all-carbon micro-conduit electrodes with hollow channels exhibit high areal capacitance of 2.35 F cm -2 (~500 F g -1 based on active material mass), high rate capability and outstanding cyclic stability (capacitance retention of ~95% over 10,000 cycles). Furthermore, Nernst-Planck-Poisson calculations elucidate the underlying mechanism of charge transfer and storage governed by sharp graphene petal edges, and thus provides insights into their outstanding electrochemical performance.

Signal transfer within a cultured asymmetric cortical neuron circuit

NASA Astrophysics Data System (ADS)

Isomura, Takuya; Shimba, Kenta; Takayama, Yuzo; Takeuchi, Akimasa; Kotani, Kiyoshi; Jimbo, Yasuhiko

2015-12-01

Objective. Simplified neuronal circuits are required for investigating information representation in nervous systems and for validating theoretical neural network models. Here, we developed patterned neuronal circuits using micro fabricated devices, comprising a micro-well array bonded to a microelectrode-array substrate. Approach. The micro-well array consisted of micrometre-scale wells connected by tunnels, all contained within a silicone slab called a micro-chamber. The design of the micro-chamber confined somata to the wells and allowed axons to grow through the tunnels bidirectionally but with a designed, unidirectional bias. We guided axons into the point of the arrow structure where one of the two tunnel entrances is located, making that the preferred direction. Main results. When rat cortical neurons were cultured in the wells, their axons grew through the tunnels and connected to neurons in adjoining wells. Unidirectional burst transfers and other asymmetric signal-propagation phenomena were observed via the substrate-embedded electrodes. Seventy-nine percent of burst transfers were in the forward direction. We also observed rapid propagation of activity from sites of local electrical stimulation, and significant effects of inhibitory synapse blockade on bursting activity. Significance. These results suggest that this simple, substrate-controlled neuronal circuit can be applied to develop in vitro models of the function of cortical microcircuits or deep neural networks, better to elucidate the laws governing the dynamics of neuronal networks.

Signal transfer within a cultured asymmetric cortical neuron circuit.

PubMed

Isomura, Takuya; Shimba, Kenta; Takayama, Yuzo; Takeuchi, Akimasa; Kotani, Kiyoshi; Jimbo, Yasuhiko

2015-12-01

Simplified neuronal circuits are required for investigating information representation in nervous systems and for validating theoretical neural network models. Here, we developed patterned neuronal circuits using micro fabricated devices, comprising a micro-well array bonded to a microelectrode-array substrate. The micro-well array consisted of micrometre-scale wells connected by tunnels, all contained within a silicone slab called a micro-chamber. The design of the micro-chamber confined somata to the wells and allowed axons to grow through the tunnels bidirectionally but with a designed, unidirectional bias. We guided axons into the point of the arrow structure where one of the two tunnel entrances is located, making that the preferred direction. When rat cortical neurons were cultured in the wells, their axons grew through the tunnels and connected to neurons in adjoining wells. Unidirectional burst transfers and other asymmetric signal-propagation phenomena were observed via the substrate-embedded electrodes. Seventy-nine percent of burst transfers were in the forward direction. We also observed rapid propagation of activity from sites of local electrical stimulation, and significant effects of inhibitory synapse blockade on bursting activity. These results suggest that this simple, substrate-controlled neuronal circuit can be applied to develop in vitro models of the function of cortical microcircuits or deep neural networks, better to elucidate the laws governing the dynamics of neuronal networks.

Integrated Electrode Arrays for Neuro-Prosthetic Implants

NASA Technical Reports Server (NTRS)

Brandon, Erik; Mojarradi, Mohammede

2003-01-01

Arrays of electrodes integrated with chip-scale packages and silicon-based integrated circuits have been proposed for use as medical electronic implants, including neuro-prosthetic devices that might be implanted in brains of patients who suffer from strokes, spinal-cord injuries, or amyotrophic lateral sclerosis. The electrodes of such a device would pick up signals from neurons in the cerebral cortex, and the integrated circuit would perform acquisition and preprocessing of signal data. The output of the integrated circuit could be used to generate, for example, commands for a robotic arm. Electrode arrays capable of acquiring electrical signals from neurons already exist, but heretofore, there has been no convenient means to integrate these arrays with integrated-circuit chips. Such integration is needed in order to eliminate the need for the extensive cabling now used to pass neural signals to data-acquisition and -processing equipment outside the body. The proposed integration would enable progress toward neuro-prostheses that would be less restrictive of patients mobility. An array of electrodes would comprise a set of thin wires of suitable length and composition protruding from and supported by a fine-pitch micro-ball grid array or chip-scale package (see figure). The associated integrated circuit would be mounted on the package face opposite the probe face, using the solder bumps (the balls of the ball grid array) to make the electrical connections between the probes and the input terminals of the integrated circuit. The key innovation is the insertion of probe wires of the appropriate length and material into the solder bumps through a reflow process, thereby fixing the probes in place and electrically connecting them with the integrated circuit. The probes could be tailored to any distribution of lengths and made of any suitable metal that could be drawn into fine wires. Furthermore, the wires could be coated with an insulating layer using anodization or other processes, to achieve the correct electrical impedance. The probe wires and the packaging materials must be biocompatible using such materials as lead-free solders. For protection, the chip and package can be coated with parylene.

Applications of Gas Imaging Micro-Well Detectors to an Advanced Compton Telescope

NASA Technical Reports Server (NTRS)

Bloser, P. F.; Hunter, S. D.; Ryan, J. M.; McConnell, M. L.; Miller, R. S.; Jackson, T. N.; Bai, B.; Jung, S.

2003-01-01

We present a concept for an Advanced Compton Telescope (ACT) based on the use of pixelized gas micro-well detectors to form a three-dimensional electron track imager. A micro-well detector consists of an array of individual micro-patterned proportional counters opposite a planar drift electrode. When combined with thin film transistor array readouts, large gas volumes may be imaged with very good spatial and energy resolution at reasonable cost. The third dimension is determined by timing the drift of the ionization electrons. The primary advantage of this approach is the excellent tracking of the Compton recoil electron that is possible in a gas volume. Such good electron tracking allows us to reduce the point spread function of a single incident photon dramatically, greatly improving the imaging capability and sensitivity. The polarization sensitivity, which relies on events with large Compton scattering angles, is particularly enhanced. We describe a possible ACT implementation of this technique, in which the gas tracking volume is surrounded by a CsI calorimeter, and present our plans to build and test a small prototype over the next three years.

Toward active-matrix lab-on-a-chip: programmable electrofluidic control enabled by arrayed oxide thin film transistors.

PubMed

Noh, Joo Hyon; Noh, Jiyong; Kreit, Eric; Heikenfeld, Jason; Rack, Philip D

2012-01-21

Agile micro- and nano-fluidic control is critical to numerous life science and chemical science synthesis as well as kinetic and thermodynamic studies. To this end, we have demonstrated the use of thin film transistor arrays as an active matrix addressing method to control an electrofluidic array. Because the active matrix method minimizes the number of control lines necessary (m + n lines for the m×n element array), the active matrix addressing method integrated with an electrofluidic platform can be a significant breakthrough for complex electrofluidic arrays (increased size or resolution) with enhanced function, agility and programmability. An amorphous indium gallium zinc oxide (a-IGZO) semiconductor active layer is used because of its high mobility of 1-15 cm(2) V(-1) s(-1), low-temperature processing and transparency for potential spectroscopy and imaging. Several electrofluidic functionalities are demonstrated using a simple 2 × 5 electrode array connected to a 2 × 5 IGZO thin film transistor array with the semiconductor channel width of 50 μm and mobility of 6.3 cm(2) V(-1) s(-1). Additionally, using the TFT device characteristics, active matrix addressing schemes are discussed as the geometry of the electrode array can be tailored to act as a storage capacitor element. Finally, requisite material and device parameters are discussed in context with a VGA scale active matrix addressed electrofluidic platform.

Micromachined three-dimensional electrode arrays for transcutaneous nerve tracking

NASA Astrophysics Data System (ADS)

Rajaraman, Swaminathan; Bragg, Julian A.; Ross, James D.; Allen, Mark G.

2011-08-01

We report the development of metal transfer micromolded (MTM) three-dimensional microelectrode arrays (3D MEAs) for a transcutaneous nerve tracking application. The measurements of electrode-skin-electrode impedance (ESEI), electromyography (EMG) and nerve conduction utilizing these minimally invasive 3D MEAs are demonstrated in this paper. The 3D MEAs used in these measurements consist of a metalized micro-tower array that can penetrate the outer layers of the skin in a painless fashion and are fabricated using MTM technology. Two techniques, an inclined UV lithography approach and a double-side exposure of thick negative tone resist, have been developed to fabricate the 3D MEA master structure. The MEAs themselves are fabricated from the master structure utilizing micromolding techniques. Metal patterns are transferred during the micromolding process, thereby ensuring reduced process steps compared to traditional silicon-based approaches. These 3D MEAs have been packaged utilizing biocompatible Kapton® substrates. ESEI measurements have been carried out on test human subjects with standard commercial wet electrodes as a reference. The 3D MEAs demonstrate an order of magnitude lower ESEI (normalized to area) compared to wet electrodes for an area that is 12.56 times smaller. This compares well with other demonstrated approaches in literature. For a nerve tracking demonstration, we have chosen EMG and nerve conduction measurements on test human subjects. The 3D MEAs show 100% improvement in signal power and SNR/√area as compared to standard electrodes. They also demonstrate larger amplitude signals and faster rise times during nerve conduction measurements. We believe that this microfabrication and packaging approach scales well to large-area, high-density arrays required for applications like nerve tracking. This development will increase the stimulation and recording fidelity of skin surface electrodes, while increasing their spatial resolution by an order of magnitude or more. Although biopotential electrode systems are not without their challenges, the non-invasive access to neural information, along with the potential for automation with associated electronic and software development, is precisely what makes this technology an excellent candidate for the next generation in diagnostic, therapeutic, and prosthetic devices.

Millimeter-scale epileptiform spike propagation patterns and their relationship to seizures

PubMed Central

Vanleer, Ann C; Blanco, Justin A; Wagenaar, Joost B; Viventi, Jonathan; Contreras, Diego; Litt, Brian

2016-01-01

Objective Current mapping of epileptic networks in patients prior to epilepsy surgery utilizes electrode arrays with sparse spatial sampling (∼1.0 cm inter-electrode spacing). Recent research demonstrates that sub-millimeter, cortical-column-scale domains have a role in seizure generation that may be clinically significant. We use high-resolution, active, flexible surface electrode arrays with 500 μm inter-electrode spacing to explore epileptiform local field potential spike propagation patterns in two dimensions recorded from subdural micro-electrocorticographic signals in vivo in cat. In this study, we aimed to develop methods to quantitatively characterize the spatiotemporal dynamics of epileptiform activity at high-resolution. Approach We topically administered a GABA-antagonist, picrotoxin, to induce acute neocortical epileptiform activity leading up to discrete electrographic seizures. We extracted features from local field potential spikes to characterize spatiotemporal patterns in these events. We then tested the hypothesis that two dimensional spike patterns during seizures were different from those between seizures. Main results We showed that spatially correlated events can be used to distinguish ictal versus interictal spikes. Significance We conclude that sub-millimeter-scale spatiotemporal spike patterns reveal network dynamics that are invisible to standard clinical recordings and contain information related to seizure-state. PMID:26859260

Millimeter-scale epileptiform spike propagation patterns and their relationship to seizures

NASA Astrophysics Data System (ADS)

Vanleer, Ann C.; Blanco, Justin A.; Wagenaar, Joost B.; Viventi, Jonathan; Contreras, Diego; Litt, Brian

2016-04-01

Objective. Current mapping of epileptic networks in patients prior to epilepsy surgery utilizes electrode arrays with sparse spatial sampling (∼1.0 cm inter-electrode spacing). Recent research demonstrates that sub-millimeter, cortical-column-scale domains have a role in seizure generation that may be clinically significant. We use high-resolution, active, flexible surface electrode arrays with 500 μm inter-electrode spacing to explore epileptiform local field potential (LFP) spike propagation patterns in two dimensions recorded from subdural micro-electrocorticographic signals in vivo in cat. In this study, we aimed to develop methods to quantitatively characterize the spatiotemporal dynamics of epileptiform activity at high-resolution. Approach. We topically administered a GABA-antagonist, picrotoxin, to induce acute neocortical epileptiform activity leading up to discrete electrographic seizures. We extracted features from LFP spikes to characterize spatiotemporal patterns in these events. We then tested the hypothesis that two-dimensional spike patterns during seizures were different from those between seizures. Main results. We showed that spatially correlated events can be used to distinguish ictal versus interictal spikes. Significance. We conclude that sub-millimeter-scale spatiotemporal spike patterns reveal network dynamics that are invisible to standard clinical recordings and contain information related to seizure-state.

A low-cost, multiplexed μECoG system for high-density recordings in freely moving rodents

NASA Astrophysics Data System (ADS)

Insanally, Michele; Trumpis, Michael; Wang, Charles; Chiang, Chia-Han; Woods, Virginia; Palopoli-Trojani, Kay; Bossi, Silvia; Froemke, Robert C.; Viventi, Jonathan

2016-04-01

Objective. Micro-electrocorticography (μECoG) offers a minimally invasive neural interface with high spatial resolution over large areas of cortex. However, electrode arrays with many contacts that are individually wired to external recording systems are cumbersome and make recordings in freely behaving rodents challenging. We report a novel high-density 60-electrode system for μECoG recording in freely moving rats. Approach. Multiplexed headstages overcome the problem of wiring complexity by combining signals from many electrodes to a smaller number of connections. We have developed a low-cost, multiplexed recording system with 60 contacts at 406 μm spacing. We characterized the quality of the electrode signals using multiple metrics that tracked spatial variation, evoked-response detectability, and decoding value. Performance of the system was validated both in anesthetized animals and freely moving awake animals. Main results. We recorded μECoG signals over the primary auditory cortex, measuring responses to acoustic stimuli across all channels. Single-trial responses had high signal-to-noise ratios (SNR) (up to 25 dB under anesthesia), and were used to rapidly measure network topography within ˜10 s by constructing all single-channel receptive fields in parallel. We characterized evoked potential amplitudes and spatial correlations across the array in the anesthetized and awake animals. Recording quality in awake animals was stable for at least 30 days. Finally, we used these responses to accurately decode auditory stimuli on single trials. Significance. This study introduces (1) a μECoG recording system based on practical hardware design and (2) a rigorous analytical method for characterizing the signal characteristics of μECoG electrode arrays. This methodology can be applied to evaluate the fidelity and lifetime of any μECoG electrode array. Our μECoG-based recording system is accessible and will be useful for studies of perception and decision-making in rodents, particularly over the entire time course of behavioral training and learning.

A High-Voltage SOI CMOS Exciter Chip for a Programmable Fluidic Processor System.

PubMed

Current, K W; Yuk, K; McConaghy, C; Gascoyne, P R C; Schwartz, J A; Vykoukal, J V; Andrews, C

2007-06-01

A high-voltage (HV) integrated circuit has been demonstrated to transport fluidic droplet samples on programmable paths across the array of driving electrodes on its hydrophobically coated surface. This exciter chip is the engine for dielectrophoresis (DEP)-based micro-fluidic lab-on-a-chip systems, creating field excitations that inject and move fluidic droplets onto and about the manipulation surface. The architecture of this chip is expandable to arrays of N X N identical HV electrode driver circuits and electrodes. The exciter chip is programmable in several senses. The routes of multiple droplets may be set arbitrarily within the bounds of the electrode array. The electrode excitation waveform voltage amplitude, phase, and frequency may be adjusted based on the system configuration and the signal required to manipulate a particular fluid droplet composition. The voltage amplitude of the electrode excitation waveform can be set from the minimum logic level up to the maximum limit of the breakdown voltage of the fabrication technology. The frequency of the electrode excitation waveform can also be set independently of its voltage, up to a maximum depending upon the type of droplets that must be driven. The exciter chip can be coated and its oxide surface used as the droplet manipulation surface or it can be used with a top-mounted, enclosed fluidic chamber consisting of a variety of materials. The HV capability of the exciter chip allows the generated DEP forces to penetrate into the enclosed chamber region and an adjustable voltage amplitude can accommodate a variety of chamber floor thicknesses. This demonstration exciter chip has a 32 x 32 array of nominally 100 V electrode drivers that are individually programmable at each time point in the procedure to either of two phases: 0deg and 180deg with respect to the reference clock. For this demonstration chip, while operating the electrodes with a 100-V peak-to-peak periodic waveform, the maximum HV electrode waveform frequency is about 200 Hz; and standard 5-V CMOS logic data communication rate is variable up to 250 kHz. This HV demonstration chip is fabricated in a 130-V 1.0-mum SOI CMOS fabrication technology, dissipates a maximum of 1.87 W, and is about 10.4 mm x 8.2 mm.

Time-dependent Increase in the Network Response to the Stimulation of Neuronal Cell Cultures on Micro-electrode Arrays.

PubMed

Gertz, Monica L; Baker, Zachary; Jose, Sharon; Peixoto, Nathalia

2017-05-29

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network dynamics in neuronal cultures. In contrast with more traditional methods, such as patch-clamping, which can only record activity from a single cell, MEAs can record simultaneously from multiple sites in a network, without requiring the arduous task of placing each electrode individually. Moreover, numerous control and stimulation configurations can be easily applied within the same experimental setup, allowing for a broad range of dynamics to be explored. One of the key dynamics of interest in these in vitro studies has been the extent to which cultured networks display properties indicative of learning. Mouse neuronal cells cultured on MEAs display an increase in response following training induced by electrical stimulation. This protocol demonstrates how to culture neuronal cells on MEAs; successfully record from over 95% of the plated dishes; establish a protocol to train the networks to respond to patterns of stimulation; and sort, plot, and interpret the results from such experiments. The use of a proprietary system for stimulating and recording neuronal cultures is demonstrated. Software packages are also used to sort neuronal units. A custom-designed graphical user interface is used to visualize post-stimulus time histograms, inter-burst intervals, and burst duration, as well as to compare the cellular response to stimulation before and after a training protocol. Finally, representative results and future directions of this research effort are discussed.

Design and fabrication of a polyimide-based microelectrode array: application in neural recording and repeatable electrolytic lesion in rat brain.

PubMed

Chen, You-Yin; Lai, Hsin-Yi; Lin, Sheng-Huang; Cho, Chien-Wen; Chao, Wen-Hung; Liao, Chia-Hsin; Tsang, Siny; Chen, Yi-Fan; Lin, Si-Yue

2009-08-30

The design and testing of a new microelectrode array, the NCTU (National Chiao Tung University) probe, was presented. Evaluation results showed it has good biocompatibility, high signal-to-noise ratio (SNR: the root mean square of background noise to the average peak-to-peak amplitude of spikes) during chronic neural recordings, and high reusability for electrolytic lesions. The probe was a flexible, polyimide-based microelectrode array with a long shaft (14.9 mm in length) and 16 electrodes (5 microm-thick and 16 microm in radius); its performance in chronic in vivo recordings was examined in rodents. To improve the precision of implantation, a metallic, impact-resistant layer was sandwiched between the polyimide layers to strengthen the probe. The three-dimensional (3D) structure of electrodes fabricated by electroplating produced rough textures that increased the effective surface area. The in vitro impedance of electrodes on the NCTU probe was 2.4+/-0.52 MOmega at 1 kHz. In addition, post-surgical neural recordings of implanted NCTU probes were conducted for up to 40 days in awake, normally behaving rats. The electrodes on the NCTU probe functioned well and had a high SNR (range: 4-5) with reliable in vivo impedance (<0.7 MOmega). The electrodes were also robust enough to functionally record events, even after the anodal current (30 microA, 10s) was repeatedly applied for 60 times. With good biocompatibility, high and stable SNR for chronic recording, and high tolerance for electrolytic lesion, the NCTU probe would serve as a useful device in future neuroscience research.

Polymer-based sensor array for phytochemical detection

NASA Astrophysics Data System (ADS)

Weerakoon, Kanchana A.; Hiremath, Nitilaksha; Chin, Bryan A.

2012-05-01

Monitoring for the appearance of volatile organic compounds emitted by plants which correspond to time of first insect attack can be used to detect the early stages of insect infestation. This paper reports a chemical sensor array consisting of polymer based chemiresistor sensors that could detect insect infestation effectively. The sensor array consists of sensors with micro electronically fabricated interdigitated electrodes, and twelve different types of electro active polymer layers. The sensor array was cheap, easy to fabricate, and could be used easily in agricultural fields. The polymer array was found to be sensitive to a variety of volatile organic compounds emitted by plants including γ-terpinene α-pinene, pcymene, farnesene, limonene and cis-hexenyl acetate. The sensor array was not only able to detect but also distinguish between these compounds. The twelve sensors produced a resistance change for each of the analytes detected, and each of these responses together produced a unique fingerprint, enabling to distinguish among these chemicals.

Carbon nanotube array based sensor

DOEpatents

Lee, Christopher L.; Noy, Aleksandr; Swierkowski, Stephan P.; Fisher, Karl A.; Woods, Bruce W.

2005-09-20

A sensor system comprising a first electrode with an array of carbon nanotubes and a second electrode. The first electrode with an array of carbon nanotubes and the second electrode are positioned to produce an air gap between the first electrode with an array of carbon nanotubes and the second electrode. A measuring device is provided for sensing changes in electrical capacitance between the first electrode with an array of carbon nanotubes and the second electrode.

PDMS based multielectrode arrays for superior in-vitro retinal stimulation and recording.

PubMed

Biswas, Satarupa; Sikdar, Debdeep; Das, Debanjan; Mahadevappa, Manjunatha; Das, Soumen

2017-08-25

Understanding of the neural response to electrical stimulation requires simultaneous recording from the various neurons of retina. Electrodes form the physical interface with the neural or retinal tissue. Successful retinal stimulation and recording demands conformal integration of these electrodes with the soft tissue to ensure establishment of proper electrical connection with the excitable tissue. Mechanical impedance of polydimethylsiloxane (PDMS) being compliant with that of retinal tissue, offers excellent potential as a substrate for metal electrodes. In this paper, Cr/Au micro electrodes with 200 μm diameter were fabricated on rigid and flexible PDMS substrates under crack free condition. Spontaneous buckling of thin films over PDMS substrates improved electrode performance circumventing the fabrication issues faced over a buckled surface. Individual electrodes from the multielectrode arrays (MEAs) were examined with electrochemical impedance spectroscopy and cyclic voltammetry. Controlled fabrication process as described here generates buckles in the metal films leading to increased electrode surface area that increases the charge storage capacity and decreases the interface impedance of the metal electrodes. At 1 kHz, impedance was reduced from 490 ± 27 kΩ to 246 ± 19 kΩ and charge storage capacity was increased from 0.40 ± 0.87 mC/cm 2 to 2.1 ± 0.87 mC/cm 2 . Neural spikes recorded with PDMS based electrodes from isolated retina also contained less noise as indicated by signal to noise ratio analysis. The present study established that the use of PDMS as a substrate for MEAs can enhance the performance of any thin film metal electrodes without incorporation of any coating layers or nanomaterials.

Ring and peg electrodes for minimally-Invasive and long-term sub-scalp EEG recordings.

PubMed

Benovitski, Y B; Lai, A; McGowan, C C; Burns, O; Maxim, V; Nayagam, D A X; Millard, R; Rathbone, G D; le Chevoir, M A; Williams, R A; Grayden, D B; May, C N; Murphy, M; D'Souza, W J; Cook, M J; Williams, C E

2017-09-01

Minimally-invasive approaches are needed for long-term reliable Electroencephalography (EEG) recordings to assist with epilepsy diagnosis, investigation and more naturalistic monitoring. This study compared three methods for long-term implantation of sub-scalp EEG electrodes. Three types of electrodes (disk, ring, and peg) were fabricated from biocompatible materials and implanted under the scalp in five ambulatory ewes for 3months. Disk electrodes were inserted into sub-pericranial pockets. Ring electrodes were tunneled under the scalp. Peg electrodes were inserted into the skull, close to the dura. EEG was continuously monitored wirelessly. High resolution CT imaging, histopathology, and impedance measurements were used to assess the status of the electrodes at the end of the study. EEG amplitude was larger in the peg compared with the disk and ring electrodes (p<0.05). Similarly, chewing artifacts were lower in the peg electrodes (p<0.05). Electrode impedance increased after long-term implantation particularly for those within the bone (p<0.01). Micro-CT scans indicated that all electrodes stayed within the sub-scalp layers. All pegs remained within the burr holes as implanted with no evidence of extrusion. Eight of 10 disks partially eroded into the bone by 1.0mm from the surface of the skull. The ring arrays remained within the sub-scalp layers close to implantation site. Histology revealed that the electrodes were encapsulated in a thin fibrous tissue adjacent to the pericranium. Overlying this was a loose connective layer and scalp. Erosion into the bone occurred under the rim of the sub-pericranial disk electrodes. The results indicate that the peg electrodes provided high quality EEG, mechanical stability, and lower chewing artifact. Whereas, ring electrode arrays tunneled under the scalp enable minimal surgical techniques to be used for implantation and removal. Copyright © 2017 Elsevier B.V. All rights reserved.

Spatial co-adaptation of cortical control columns in a micro-ECoG brain-computer interface

NASA Astrophysics Data System (ADS)

Rouse, A. G.; Williams, J. J.; Wheeler, J. J.; Moran, D. W.

2016-10-01

Objective. Electrocorticography (ECoG) has been used for a range of applications including electrophysiological mapping, epilepsy monitoring, and more recently as a recording modality for brain-computer interfaces (BCIs). Studies that examine ECoG electrodes designed and implanted chronically solely for BCI applications remain limited. The present study explored how two key factors influence chronic, closed-loop ECoG BCI: (i) the effect of inter-electrode distance on BCI performance and (ii) the differences in neural adaptation and performance when fixed versus adaptive BCI decoding weights are used. Approach. The amplitudes of epidural micro-ECoG signals between 75 and 105 Hz with 300 μm diameter electrodes were used for one-dimensional and two-dimensional BCI tasks. The effect of inter-electrode distance on BCI control was tested between 3 and 15 mm. Additionally, the performance and cortical modulation differences between constant, fixed decoding using a small subset of channels versus adaptive decoding weights using the entire array were explored. Main results. Successful BCI control was possible with two electrodes separated by 9 and 15 mm. Performance decreased and the signals became more correlated when the electrodes were only 3 mm apart. BCI performance in a 2D BCI task improved significantly when using adaptive decoding weights (80%-90%) compared to using constant, fixed weights (50%-60%). Additionally, modulation increased for channels previously unavailable for BCI control under the fixed decoding scheme upon switching to the adaptive, all-channel scheme. Significance. Our results clearly show that neural activity under a BCI recording electrode (which we define as a ‘cortical control column’) readily adapts to generate an appropriate control signal. These results show that the practical minimal spatial resolution of these control columns with micro-ECoG BCI is likely on the order of 3 mm. Additionally, they show that the combination and interaction between neural adaptation and machine learning are critical to optimizing ECoG BCI performance.

Development of a microfluidic device for simultaneous mixing and pumping

NASA Astrophysics Data System (ADS)

Kim, Byoung Jae; Yoon, Sang Youl; Lee, Kyung Heon; Sung, Hyung Jin

2009-01-01

We conducted experimental and numerical studies aimed at developing a microfluidic device capable of simultaneous mixing while pumping. The proposed multifunctional device makes use of alternating current electroosmotic flow and adopts an array of planar asymmetric microelectrodes with a diagonal or herringbone shape. The pumping performance was assessed in terms of the fluid velocity at the center of the microchannel, obtained by micro PIV. To assess the mixing, flow visualizations were carried out over the electrodes to verify the lateral flows. The mixing degree was quantified in terms of a mixing efficiency obtained by three-dimensional numerical simulations. The results showed that simultaneous mixing and pumping was achieved in the channels with diagonal or herringbone electrode configurations. A herringbone electrode configuration showed better pumping compared with a reference, as well as enhanced mixing.

Micromachined electrode array

DOEpatents

Okandan, Murat; Wessendorf, Kurt O.

2007-12-11

An electrode array is disclosed which has applications for neural stimulation and sensing. The electrode array, in certain embodiments, can include a plurality of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. In other embodiments of the electrode array, the electrodes can be fixed to the substrate. The electrode array can be formed from a combination of bulk and surface micromachining, and can include electrode tips having an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis.

Network dynamics of 3D engineered neuronal cultures: a new experimental model for in-vitro electrophysiology.

PubMed

Frega, Monica; Tedesco, Mariateresa; Massobrio, Paolo; Pesce, Mattia; Martinoia, Sergio

2014-06-30

Despite the extensive use of in-vitro models for neuroscientific investigations and notwithstanding the growing field of network electrophysiology, all studies on cultured cells devoted to elucidate neurophysiological mechanisms and computational properties, are based on 2D neuronal networks. These networks are usually grown onto specific rigid substrates (also with embedded electrodes) and lack of most of the constituents of the in-vivo like environment: cell morphology, cell-to-cell interaction and neuritic outgrowth in all directions. Cells in a brain region develop in a 3D space and interact with a complex multi-cellular environment and extracellular matrix. Under this perspective, 3D networks coupled to micro-transducer arrays, represent a new and powerful in-vitro model capable of better emulating in-vivo physiology. In this work, we present a new experimental paradigm constituted by 3D hippocampal networks coupled to Micro-Electrode-Arrays (MEAs) and we show how the features of the recorded network dynamics differ from the corresponding 2D network model. Further development of the proposed 3D in-vitro model by adding embedded functionalized scaffolds might open new prospects for manipulating, stimulating and recording the neuronal activity to elucidate neurophysiological mechanisms and to design bio-hybrid microsystems.

Network dynamics of 3D engineered neuronal cultures: a new experimental model for in-vitro electrophysiology

PubMed Central

Frega, Monica; Tedesco, Mariateresa; Massobrio, Paolo; Pesce, Mattia; Martinoia, Sergio

2014-01-01

Despite the extensive use of in-vitro models for neuroscientific investigations and notwithstanding the growing field of network electrophysiology, all studies on cultured cells devoted to elucidate neurophysiological mechanisms and computational properties, are based on 2D neuronal networks. These networks are usually grown onto specific rigid substrates (also with embedded electrodes) and lack of most of the constituents of the in-vivo like environment: cell morphology, cell-to-cell interaction and neuritic outgrowth in all directions. Cells in a brain region develop in a 3D space and interact with a complex multi-cellular environment and extracellular matrix. Under this perspective, 3D networks coupled to micro-transducer arrays, represent a new and powerful in-vitro model capable of better emulating in-vivo physiology. In this work, we present a new experimental paradigm constituted by 3D hippocampal networks coupled to Micro-Electrode-Arrays (MEAs) and we show how the features of the recorded network dynamics differ from the corresponding 2D network model. Further development of the proposed 3D in-vitro model by adding embedded functionalized scaffolds might open new prospects for manipulating, stimulating and recording the neuronal activity to elucidate neurophysiological mechanisms and to design bio-hybrid microsystems. PMID:24976386

A Micro-Electrode Array device coupled to a laser-based system for the local stimulation of neurons by optical release of glutamate.

PubMed

Ghezzi, Diego; Menegon, Andrea; Pedrocchi, Alessandra; Valtorta, Flavia; Ferrigno, Giancarlo

2008-10-30

Optical stimulation is a promising approach to investigate the local dynamic responses of cultured neurons. In particular, flash photolysis of caged compounds offers the advantage of allowing the rapid change of concentration of either extracellular or intracellular molecules, such as neurotransmitters or second messengers, for the stimulation or modulation of neuronal activity. We describe here the use of an ultra-violet (UV) laser diode coupled to an optical fibre for the local activation of caged compounds combined with a Micro-Electrode Array (MEA) device. Local uncaging was achieved by UV irradiation through the optical fibre previously positioned by using a red laser diode. The size of the stimulation was determined using caged fluorescein, whereas its efficacy was tested by studying the effect of uncaging the neurotransmitter glutamate. Uncaged glutamate evoked neuronal responses that were recorded using either fluorescence measurements or electrophysiological recordings with MEAs, thus showing the ability of our system to induce local neuronal excitation. This method allows overcoming the limitations of the MEA system related to unfocused electrical stimulation and induction of electrical artefacts. In addition, the coupling of a UV laser diode to an optical fibre allows a precise local stimulation and a quick change of the stimulation point.

Thylakoid-Deposited Micro-Pillar Electrodes for Enhanced Direct Extraction of Photosynthetic Electrons

PubMed Central

Ryu, DongHyun; Kim, Yong Jae; Kim, Seon Il; Hong, Hyeonaug; Ahn, Hyun S.

2018-01-01

Photosynthesis converts solar energy to electricity in a highly efficient manner. Since only water is needed as fuel for energy conversion, this highly efficient energy conversion process has been rigorously investigated. In particular, photosynthetic apparatus, such as photosystem II (PSII), photosystem I (PSI), or thylakoids, have been isolated from various plants to construct bio-hybrid anodes. Although PSII or PSI decorated anodes have shown potentials, there still remain challenges, such as poor stability of PSII-based systems or need for electron donors other than water molecules of PSI-based systems. Thylakoid membranes are relatively stable after isolation and they contain all the necessary photosynthetic apparatus including the PSII and PSI. To increase electrical connections between thylakoids and anodes, nanomaterials such as carbon nanotubes, nanowires, nanoparticles, or graphene have been employed. However, since they rely on the secondary electrical connections between thylakoids and anodes; it is desired to achieve larger direct contacts between them. Here, we aimed to develop micro-pillar (MP) array anodes to maximize direct contact with thylakoids. The thylakoid morphology was analyzed and the MP array was designed to maximize direct contact with thylakoids. The performance of MP anodes and a photosynthetic fuel cell based on MP electrodes was demonstrated and analyzed. PMID:29587387

Microchannel neural interface manufacture by stacking silicone and metal foil laminae

NASA Astrophysics Data System (ADS)

Lancashire, Henry T.; Vanhoestenberghe, Anne; Pendegrass, Catherine J.; Ajam, Yazan Al; Magee, Elliot; Donaldson, Nick; Blunn, Gordon W.

2016-06-01

Objective. Microchannel neural interfaces (MNIs) overcome problems with recording from peripheral nerves by amplifying signals independent of node of Ranvier position. Selective recording and stimulation using an MNI requires good insulation between microchannels and a high electrode density. We propose that stacking microchannel laminae will improve selectivity over single layer MNI designs due to the increase in electrode number and an improvement in microchannel sealing. Approach. This paper describes a manufacturing method for creating MNIs which overcomes limitations on electrode connectivity and microchannel sealing. Laser cut silicone—metal foil laminae were stacked using plasma bonding to create an array of microchannels containing tripolar electrodes. Electrodes were DC etched and electrode impedance and cyclic voltammetry were tested. Main results. MNIs with 100 μm and 200 μm diameter microchannels were manufactured. High electrode density MNIs are achievable with electrodes present in every microchannel. Electrode impedances of 27.2 ± 19.8 kΩ at 1 kHz were achieved. Following two months of implantation in Lewis rat sciatic nerve, micro-fascicles were observed regenerating through the MNI microchannels. Significance. Selective MNIs with the peripheral nervous system may allow upper limb amputees to control prostheses intuitively.

Electrode array for neural stimulation

DOEpatents

Wessendorf, Kurt O [Albuquerque, NM; Okandan, Murat [Edgewood, NM; Stein, David J [Albuquerque, NM; Yang, Pin [Albuquerque, NM; Cesarano, III, Joseph; Dellinger, Jennifer [Albuquerque, NM

2011-08-16

An electrode array for neural stimulation is disclosed which has particular applications for use in a retinal prosthesis. The electrode array can be formed as a hermetically-sealed two-part ceramic package which includes an electronic circuit such as a demultiplexer circuit encapsulated therein. A relatively large number (up to 1000 or more) of individually-addressable electrodes are provided on a curved surface of a ceramic base portion the electrode array, while a much smaller number of electrical connections are provided on a ceramic lid of the electrode array. The base and lid can be attached using a metal-to-metal seal formed by laser brazing. Electrical connections to the electrode array can be provided by a flexible ribbon cable which can also be used to secure the electrode array in place.

Solid-state probe based electrochemical aptasensor for cocaine: a potentially convenient, sensitive, repeatable, and integrated sensing platform for drugs.

PubMed

Du, Yan; Chen, Chaogui; Yin, Jianyuan; Li, Bingling; Zhou, Ming; Dong, Shaojun; Wang, Erkang

2010-02-15

Aptamers, which are artificial oligonucleotides selected in vitro, have been employed to design novel biosensors (i.e., aptasensors). In this work, we first constructed a label-free electrochemical aptasensor introducing a probe immobilization technique by the use of a layer-by-layer (LBL) self-assembled multilayer with ferrocene-appended poly(ethyleneimine) (Fc-PEI) on an indium tin oxide (ITO) array electrode for detection of cocaine. The Fc-PEI and gold nanoparticles (AuNPs) were LBL assembled on the electrode surface via electrostatic interaction. Then, cocaine aptamer fragments, SH-C2, were covalently labeled onto the outermost AuNP layer. When the target cocaine and cocaine aptamer C1 were present simultaneously, the SH-C2 layer hybridized partly with C1 to bind the cocaine, which led to a decreased differential pulse voltammetry (DPV) signal of Fc-PEI. This DPV signal change could be used to sensitively detect cocaine with the lowest detectable concentration down to 0.1 microM and the detection range up to 38.8 microM, which falls in the the expected range for medical use of detecting drug abuse involving cocaine. Meanwhile, the sensor was specific to cocaine in complex biologic fluids such as human plasma, human saliva, etc. The sensing strategy had general applicability, and the detection of thrombin could also be realized, displayed a low detection limit, and exhibited worthiness to other analytes. The aptasensor based on the array electrode held promising potential for integration of the sensing ability in multianalysis for simultaneous detection.

Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model.

PubMed

Tedesco, Mariateresa; Frega, Monica; Martinoia, Sergio; Pesce, Mattia; Massobrio, Paolo

2015-10-18

Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the gold-standard experimental model to study basic neurophysiological mechanisms involved in the formation and maintenance of neuronal cell assemblies. However, in vitro studies have been limited to the recording of the electrophysiological activity generated by bi-dimensional (2D) neural networks. Nonetheless, given the intricate relationship between structure and dynamics, a significant improvement is necessary to investigate the formation and the developing dynamics of three-dimensional (3D) networks. In this work, a novel experimental platform in which 3D hippocampal or cortical networks are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are realized by seeding neurons in a scaffold constituted of glass microbeads (30-40 µm in diameter) on which neurons are able to grow and form complex interconnected 3D assemblies. In this way, it is possible to design engineered 3D networks made up of 5-8 layers with an expected final cell density. The increasing complexity in the morphological organization of the 3D assembly induces an enhancement of the electrophysiological patterns displayed by this type of networks. Compared with the standard 2D networks, where highly stereotyped bursting activity emerges, the 3D structure alters the bursting activity in terms of duration and frequency, as well as it allows observation of more random spiking activity. In this sense, the developed 3D model more closely resembles in vivo neural networks.

Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

PubMed Central

Tedesco, Mariateresa; Frega, Monica; Martinoia, Sergio; Pesce, Mattia; Massobrio, Paolo

2015-01-01

Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the gold-standard experimental model to study basic neurophysiological mechanisms involved in the formation and maintenance of neuronal cell assemblies. However, in vitro studies have been limited to the recording of the electrophysiological activity generated by bi-dimensional (2D) neural networks. Nonetheless, given the intricate relationship between structure and dynamics, a significant improvement is necessary to investigate the formation and the developing dynamics of three-dimensional (3D) networks. In this work, a novel experimental platform in which 3D hippocampal or cortical networks are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are realized by seeding neurons in a scaffold constituted of glass microbeads (30-40 µm in diameter) on which neurons are able to grow and form complex interconnected 3D assemblies. In this way, it is possible to design engineered 3D networks made up of 5-8 layers with an expected final cell density. The increasing complexity in the morphological organization of the 3D assembly induces an enhancement of the electrophysiological patterns displayed by this type of networks. Compared with the standard 2D networks, where highly stereotyped bursting activity emerges, the 3D structure alters the bursting activity in terms of duration and frequency, as well as it allows observation of more random spiking activity. In this sense, the developed 3D model more closely resembles in vivo neural networks. PMID:26554533

Organic vapor discrimination with chemiresistor arrays of temperature modulated tin-oxide nanowires and thiolate-monolayer-protected gold nanoparticles.

PubMed

Scholten, K; Bohrer, F I; Dattoli, E; Lu, W; Zellers, E T

2011-03-25

This paper explores the discrimination of organic vapors with arrays of chemiresistors (CRs) employing interface layers of tin-oxide nanowires (NWs) and thiolate-monolayer-protected gold nanoparticles (MPNs). The former devices use contact-printed mats of NWs on micro-hotplate membranes to bridge a pair of metal electrodes. Oxidation at the NW surface causes changes in charge transport, the temperature dependence of which differs among different vapors, permitting vapor discrimination. The latter devices use solvent cast films of MPNs on interdigital electrodes operated at room temperature. Sorption into the organic monolayers causes changes in film tunneling resistance that differ among different vapors and MPN structures, permitting vapor discrimination. Here, we compare the performance and assess the 'complementarity' of these two types of sensors. Calibrated responses from an NW CR operated at two different temperatures and from a set of four different MPN CRs were generated for three test vapors: n-hexane, toluene, and nitromethane. This pooled data set was then analyzed using principal components regression classification models with varying degrees of random error superimposed on the responses via Monte Carlo simulation in order to estimate the rates of recognition/discrimination for arrays comprising different combinations of sensors. Results indicate that the diversity of most of the dual MPN-CR arrays exceeds that of the dual NW-CR array. Additionally, in assessing all possible arrays of 4-6 CR sensors, the recognition rates of the hybrid arrays (i.e. MPN + NW) were no better than that of the 4-sensor array containing only MPN CRs.

Real Time Monitoring of Temperature of a Micro Proton Exchange Membrane Fuel Cell

PubMed Central

Lee, Chi-Yuan; Lee, Shuo-Jen; Hu, Yuh-Chung; Shih, Wen-Pin; Fan, Wei-Yuan; Chuang, Chih-Wei

2009-01-01

Silicon micro-hole arrays (Si-MHA) were fabricated as a gas diffusion layer (GDL) in a micro fuel cell using the micro-electro-mechanical-systems (MEMS) fabrication technique. The resistance temperature detector (RTD) sensor was integrated with the GDL on a bipolar plate to measure the temperature inside the fuel cell. Experimental results demonstrate that temperature was generally linearly related to resistance and that accuracy and sensitivity were within 0.5 °C and 1.68×10−3/°C, respectively. The best experimental performance was 9.37 mW/cm2 at an H2/O2 dry gas flow rate of 30/30 SCCM. Fuel cell temperature during operation was 27 °C, as measured using thermocouples in contact with the backside of the electrode. Fuel cell operating temperature measured in situ was 30.5 °C. PMID:22573963

Flexible retinal electrode array

DOEpatents

Okandan, Murat [Albuquerque, NM; Wessendorf, Kurt O [Albuquerque, NM; Christenson, Todd R [Albuquerque, NM

2006-10-24

An electrode array which has applications for neural stimulation and sensing. The electrode array can include a large number of electrodes each of which is flexibly attached to a common substrate using a plurality of springs to allow the electrodes to move independently. The electrode array can be formed from a combination of bulk and surface micromachining, with electrode tips that can include an electroplated metal (e.g. platinum, iridium, gold or titanium) or a metal oxide (e.g. iridium oxide) for biocompatibility. The electrode array can be used to form a part of a neural prosthesis, and is particularly well adapted for use in an implantable retinal prosthesis where the electrodes can be tailored to provide a uniform gentle contact pressure with optional sensing of this contact pressure at one or more of the electrodes.

Guiding pancreatic beta cells to target electrodes in a whole-cell biosensor for diabetes.

PubMed

Pedraza, Eileen; Karajić, Aleksandar; Raoux, Matthieu; Perrier, Romain; Pirog, Antoine; Lebreton, Fanny; Arbault, Stéphane; Gaitan, Julien; Renaud, Sylvie; Kuhn, Alexander; Lang, Jochen

2015-10-07

We are developing a cell-based bioelectronic glucose sensor that exploits the multi-parametric sensing ability of pancreatic islet cells for the treatment of diabetes. These cells sense changes in the concentration of glucose and physiological hormones and immediately react by generating electrical signals. In our sensor, signals from multiple cells are recorded as field potentials by a micro-electrode array (MEA). Thus, cell response to various factors can be assessed rapidly and with high throughput. However, signal quality and consequently overall sensor performance rely critically on close cell-electrode proximity. Therefore, we present here a non-invasive method of further exploiting the electrical properties of these cells to guide them towards multiple micro-electrodes via electrophoresis. Parameters were optimized by measuring the cell's zeta potential and modeling the electric field distribution. Clonal and primary mouse or human β-cells migrated directly to target electrodes during the application of a 1 V potential between MEA electrodes for 3 minutes. The morphology, insulin secretion, and electrophysiological characteristics were not altered compared to controls. Thus, cell manipulation on standard MEAs was achieved without introducing any external components and while maintaining the performance of the biosensor. Since the analysis of the cells' electrical activity was performed in real time via on-chip recording and processing, this work demonstrates that our biosensor is operational from the first step of electrically guiding cells to the final step of automatic recognition. Our favorable results with pancreatic islets, which are highly sensitive and fragile cells, are encouraging for the extension of this technique to other cell types and microarray devices.

Ultra-Sensitive Strain Sensor Based on Flexible Poly(vinylidene fluoride) Piezoelectric Film

NASA Astrophysics Data System (ADS)

Lu, Kai; Huang, Wen; Guo, Junxiong; Gong, Tianxun; Wei, Xiongbang; Lu, Bing-Wei; Liu, Si-Yi; Yu, Bin

2018-03-01

A flexible 4 × 4 sensor array with 16 micro-scale capacitive units has been demonstrated based on flexible piezoelectric poly(vinylidene fluoride) (PVDF) film. The piezoelectricity and surface morphology of the PVDF were examined by optical imaging and piezoresponse force microscopy (PFM). The PFM shows phase contrast, indicating clear interface between the PVDF and electrode. The electro-mechanical properties show that the sensor exhibits excellent output response and an ultra-high signal-to-noise ratio. The output voltage and the applied pressure possess linear relationship with a slope of 12 mV/kPa. The hold-and-release output characteristics recover in less than 2.5 μs, demonstrating outstanding electro-mechanical response. Additionally, signal interference between the adjacent arrays has been investigated via theoretical simulation. The results show the interference reduces with decreasing pressure at a rate of 0.028 mV/kPa, highly scalable with electrode size and becoming insignificant for pressure level under 178 kPa.

Ultra-Sensitive Strain Sensor Based on Flexible Poly(vinylidene fluoride) Piezoelectric Film.

PubMed

Lu, Kai; Huang, Wen; Guo, Junxiong; Gong, Tianxun; Wei, Xiongbang; Lu, Bing-Wei; Liu, Si-Yi; Yu, Bin

2018-03-14

A flexible 4 × 4 sensor array with 16 micro-scale capacitive units has been demonstrated based on flexible piezoelectric poly(vinylidene fluoride) (PVDF) film. The piezoelectricity and surface morphology of the PVDF were examined by optical imaging and piezoresponse force microscopy (PFM). The PFM shows phase contrast, indicating clear interface between the PVDF and electrode. The electro-mechanical properties show that the sensor exhibits excellent output response and an ultra-high signal-to-noise ratio. The output voltage and the applied pressure possess linear relationship with a slope of 12 mV/kPa. The hold-and-release output characteristics recover in less than 2.5 μs, demonstrating outstanding electro-mechanical response. Additionally, signal interference between the adjacent arrays has been investigated via theoretical simulation. The results show the interference reduces with decreasing pressure at a rate of 0.028 mV/kPa, highly scalable with electrode size and becoming insignificant for pressure level under 178 kPa.

Strategy towards independent electrical stimulation from cochlear implants: Guided auditory neuron growth on topographically modified nanocrystalline diamond.

PubMed

Cai, Yixiao; Edin, Fredrik; Jin, Zhe; Alexsson, Andrei; Gudjonsson, Olafur; Liu, Wei; Rask-Andersen, Helge; Karlsson, Mikael; Li, Hao

2016-02-01

Cochlear implants (CI) have been used for several decades to treat patients with profound hearing loss. Nevertheless, results vary between individuals, and fine hearing is generally poor due to the lack of discrete neural stimulation from the individual receptor hair cells. A major problem is the deliverance of independent stimulation signals to individual auditory neurons. Fine hearing requires significantly more stimulation contacts with intimate neuron/electrode interphases from ordered axonal re-growth, something current CI technology cannot provide. Here, we demonstrate the potential application of micro-textured nanocrystalline diamond (NCD) surfaces on CI electrode arrays. Such textured NCD surfaces consist of micrometer-sized nail-head-shaped pillars (size 5×5μm(2)) made with sequences of micro/nano-fabrication processes, including sputtering, photolithography and plasma etching. The results show that human and murine inner-ear ganglion neurites and, potentially, neural progenitor cells can attach to patterned NCD surfaces without an extracellular matrix coating. Microscopic methods revealed adhesion and neural growth, specifically along the nail-head-shaped NCD pillars in an ordered manner, rather than in non-textured areas. This pattern was established when the inter-NCD pillar distance varied between 4 and 9μm. The findings demonstrate that regenerating auditory neurons show a strong affinity to the NCD pillars, and the technique could be used for neural guidance and the creation of new neural networks. Together with the NCD's unique anti-bacterial and electrical properties, patterned NCD surfaces could provide designed neural/electrode interfaces to create independent electrical stimulation signals in CI electrode arrays for the neural population. Cochlear implant is currently a successful way to treat sensorineural hearing loss and deafness especially in children. Although clinically successful, patients' fine hearing cannot be completely restored. One problem is the amount of the electrodes; 12-20 electrodes are used to replace the function of 3400 inner hair cells. Intense research is ongoing aiming to increase the number of electrodes. This study demonstrates the use of nanocrystalline diamond as a potential nerve-electrode interface. Micrometer-sized nanocrystalline diamond pillars showed high affinity to regenerated human neurons, which grew into a pre-defined network based on the pillar design. Our findings are of particular interest since they can be applied on any silicon-based implant to increase electrode count and to achieve individual neuron stimulation patterns. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Microplasma generating array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopwood, Jeffrey A.; Wu, Chen; Hoskinson, Alan R.

A microplasma generator includes first and second conductive resonators disposed on a first surface of a dielectric substrate. The first and second conductive resonators are arranged in line with one another with a gap defined between a first end of each resonator. A ground plane is disposed on a second surface of the dielectric substrate and a second end of each of the first and second resonators is coupled to the ground plane. A power input connector is coupled to the first resonator at a first predetermined distance from the second end chosen as a function of the impedance ofmore » the first conductive resonator. A microplasma generating array includes a number of resonators in a dielectric material substrate with one end of each resonator coupled to ground. A micro-plasma is generated at the non-grounded end of each resonator. The substrate includes a ground electrode and the microplasmas are generated between the non-grounded end of the resonator and the ground electrode. The coupling of each resonator to ground may be made through controlled switches in order to turn each resonator off or on and therefore control where and when a microplasma will be created in the array.« less

A Diamond Electron Tunneling Micro-Electromechanical Sensor

NASA Technical Reports Server (NTRS)

Albin, Sacharia

2000-01-01

A new pressure sensing device using field emission from diamond coated silicon tips has been developed. A high electric field applied between a nano-tip array and a diaphragm configured as electrodes produces electron emission governed by the Fowler Nordheim equation. The electron emission is very sensitive to the separation between the diaphragm and the tips, which is fixed at an initial spacing and bonded such that a cavity is created between them. Pressure applied to the diaphragm decreases the spacing between the electrodes, thereby increasing the number of electrons emitted. Silicon has been used as a substrate on which arrays of diamond coated sharp tips have been fabricated for electron emission. Also, a diaphragm has been made using wet orientation dependent etching. These two structures were bonded together using epoxy and tested. Current - voltage measurements were made at varying pressures for 1-5 V biasing conditions. The sensitivity was found to be 2.13 mV/V/psi for a 20 x 20 array, which is comparable to that of silicon piezoresistive transducers. Thinner diaphragms as well as alternative methods of bonding are expected to improve the electrical characteristics of the device. This transducer will find applications in many engineering fields for pressure measurement.

Safety, reliability, and operability of cochlear implant electrode arrays coated with biocompatible polymer.

PubMed

Kinoshita, Makoto; Kikkawa, Yayoi S; Sakamoto, Takashi; Kondo, Kenji; Ishihara, Kazuhiko; Konno, Tomohiro; Pawsey, Nick; Yamasoba, Tatsuya

2015-04-01

Polymer-coated electrodes can reduce surgically-induced trauma associated with the insertion of a cochlear implant (CI) electrode array. To evaluate if insertion trauma in CI surgery can be reduced by using electrode arrays coated with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. We analyzed characteristics of the Contour Advance electrode arrays coated with MPC polymer. To assess surgical trauma during electrode insertion, polymer-coated or uncoated (n = 5 each) animal electrode arrays were implanted in guinea pig cochleae and operability and electrophysiological and histological changes were assessed. Under light and scanning electron microscopy, polymer-coated electrodes did not appear different from uncoated electrodes, and no change was observed after mechanical stressing of the arrays. Electrode insertion was significantly easier when polymer-coated electrodes were used. Auditory brainstem response (ABR) thresholds did not differ between groups, but p1-n1 amplitudes of the coated group were larger compared with the uncoated group at 32 kHz at 28 days after surgery. The survival of outer hair cells and spiral ganglion cells was significantly greater in the polymer-coated group.

ZIF-8 Cooperating in TiN/Ti/Si Nanorods as Efficient Anodes in Micro-Lithium-Ion-Batteries.

PubMed

Yu, Yingjian; Yue, Chuang; Lin, Xionggui; Sun, Shibo; Gu, Jinping; He, Xu; Zhang, Chuanhui; Lin, Wei; Lin, Donghai; Liao, Xinli; Xu, Binbin; Wu, Suntao; Zheng, Mingsen; Li, Jing; Kang, Junyong; Lin, Liwei

2016-02-17

Zeolite imidazolate framework-8 (ZIF-8) nanoparticles embedded in TiN/Ti/Si nanorod (NR) arrays without pyrolysis have shown increased energy storage capacity as anodes for lithium ion batteries (LIBs). A high capacity of 1650 μAh cm(-2) has been achieved in this ZIF-8 composited multilayered electrode, which is ∼100 times higher than the plain electrodes made of only silicon NR. According to the electrochemical impedance spectroscopy (EIS) and (1)H nuclear magnetic resonance (NMR) characterizations, the improved diffusion of lithium ions in ZIF-8 and boosted electron/Li(+) transfer by the ZIF-8/TiN/Ti multilayer coating are proposed to be responsible for the enhanced energy storage ability. The first-principles calculations further indicate the favorable accessibility of lithium with appropriate size to diffuse in the open pores of ZIF-8. This work broadens the application of ZIF-8 to silicon-based LIBs electrodes without the pyrolysis and provides design guidelines for other metal-organic frameworks/Si composite electrodes.

Development of a common biosensor format for an enzyme based biosensor array to monitor fruit quality.

PubMed

Jawaheer, Shobha; White, S F; Rughooputh, S D D V; Cullen, David C

2003-10-15

Individual enzyme-based biosensors involving three-electrode systems were developed for the detection of analytes comprising markers of the stage of maturity and quality in selected fruits of economic importance to tropical countries. Importantly, a common fabrication format has been developed to simplify manufacture and allow future integration of the individual sensors into a single multi-sensor array. Specifically, sensors for beta-D-glucose, total D-glucose, sucrose and ascorbic acid have been developed. Pectin, a natural polysaccharide present in plant cells, was used as a novel matrix to enhance enzyme entrapment and stabilisation in the sensors. Except for ascorbic acid, all the sensors function via the detection of enzymatically generated H2O2 at rhodinised carbon electrodes. Since ascorbic acid is electrochemically active at the working potential chosen (+350 mV vs. Ag/AgCl), it was measured directly. Enzyme sensors demonstrated expected response with respect to their substrates, typically 0-0.8 microA/20 mm2 electrode area response over analyte ranges of 0-7 mM. Interferences related to electrochemically active compounds present in fruits under study were significantly reduced by inclusion of a suitable cellulose acetate (CA) membrane or by enzymatic inactivation with ascorbate oxidase. Initial development was carried out into production of biosensor arrays. CA membranes were used to improve the linear range of the sensors, producing up to a fivefold improvement in the detection range compared to sensors without an additional diffusion barrier.

Low-Cost Photolithographic Fabrication of Nanowires and Microfilters for Advanced Bioassay Devices

PubMed Central

Doan, Nhi M.; Qiang, Liangliang; Li, Zhe; Vaddiraju, Santhisagar; Bishop, Gregory W.; Rusling, James F.; Papadimitrakopoulos, Fotios

2015-01-01

Integrated microfluidic devices with nanosized array electrodes and microfiltration capabilities can greatly increase sensitivity and enhance automation in immunoassay devices. In this contribution, we utilize the edge-patterning method of thin aluminum (Al) films in order to form nano- to micron-sized gaps. Evaporation of high work-function metals (i.e., Au, Ag, etc.) on these gaps, followed by Al lift-off, enables the formation of electrical uniform nanowires from low-cost, plastic-based, photomasks. By replacing Al with chromium (Cr), the formation of high resolution, custom-made photomasks that are ideal for low-cost fabrication of a plurality of array devices were realized. To demonstrate the feasibility of such Cr photomasks, SU-8 micro-pillar masters were formed and replicated into PDMS to produce micron-sized filters with 3–4 µm gaps and an aspect ratio of 3. These microfilters were capable of retaining 6 µm beads within a localized site, while allowing solvent flow. The combination of nanowire arrays and micro-pillar filtration opens new perspectives for rapid R&D screening of various microfluidic-based immunoassay geometries, where analyte pre-concentration and highly sensitive, electrochemical detection can be readily co-localized. PMID:25774709

Functionalized carbon micro/nanostructures for biomolecular detection

NASA Astrophysics Data System (ADS)

Penmatsa, Varun

Advancements in the micro-and nano-scale fabrication techniques have opened up new avenues for the development of portable, scalable and easier-to-use biosensors. Over the last few years, electrodes made of carbon have been widely used as sensing units in biosensors due to their attractive physiochemical properties. The aim of this research is to investigate different strategies to develop functionalized high surface carbon micro/nano-structures for electrochemical and biosensing devices. High aspect ratio three-dimensional carbon microarrays were fabricated via carbon microelectromechanical systems (C-MEMS) technique, which is based on pyrolyzing pre-patterned organic photoresist polymers. To further increase the surface area of the carbon microstructures, surface porosity was introduced by two strategies, i.e. (i) using F127 as porogen and (ii) oxygen reactive ion etch (RIE) treatment. Electrochemical characterization showed that porous carbon thin film electrodes prepared by using F127 as porogen had an effective surface area (Aeff 185%) compared to the conventional carbon electrode. To achieve enhanced electrochemical sensitivity for C-MEMS based functional devices, graphene was conformally coated onto high aspect ratio three-dimensional (3D) carbon micropillar arrays using electrostatic spray deposition (ESD) technique. The amperometric response of graphene/carbon micropillar electrode arrays exhibited higher electrochemical activity, improved charge transfer and a linear response towards H2O2 detection between 250μM to 5.5mM. Furthermore, carbon structures with dimensions from 50 nano-to micrometer level have been fabricated by pyrolyzing photo-nanoimprint lithography patterned organic resist polymer. Microstructure, elemental composition and resistivity characterization of the carbon nanostructures produced by this process were very similar to conventional photoresist derived carbon. Surface functionalization of the carbon nanostructures was performed using direct amination technique. Considering the need for requisite functional groups to covalently attach bioreceptors on the carbon surface for biomolecule detection, different oxidation techniques were compared to study the types of carbon-oxygen groups formed on the surface and their percentages with respect to different oxidation pretreatment times. Finally, a label-free detection strategy using signaling aptamer/protein binding complex for platelet-derived growth factor oncoprotein detection on functionalized three-dimensional carbon microarrays platform was demonstrated. The sensor showed near linear relationship between the relative fluorescence difference and protein concentration even in the sub-nanomolar range with an excellent detection limit of 5 pmol.

Virtual electrodes for high-density electrode arrays

DOEpatents

Cela, Carlos J.; Lazzi, Gianluca

2015-10-13

The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

Electronic Tongue Containing Redox and Conductivity Sensors

NASA Technical Reports Server (NTRS)

Buehler, Martin

2007-01-01

The Electronic Tongue (E-tongue 2) is an assembly of sensors for measuring concentrations of metal ions and possibly other contaminants in water. Potential uses for electronic tongues include monitoring the chemical quality of water in a variety of natural, industrial, and laboratory settings, and detecting micro-organisms indirectly by measuring microbially influenced corrosion. The device includes a heater, a temperature sensor, an oxidation/reduction (redox) sensor pair, an electrical sensor, an array of eight galvanic cells, and eight ion-specific electrodes.

Surgical implications of perimodiolar cochlear implant electrode design: avoiding intracochlear damage and scala vestibuli insertion.

PubMed

Briggs, R J; Tykocinski, M; Saunders, E; Hellier, W; Dahm, M; Pyman, B; Clark, G M

2001-09-01

To review the mechanisms and nature of intracochlear damage associated with cochlear implant electrode array insertion, in particular, the various perimodiolar electrode designs. Make recommendations regarding surgical techniques for the Nucleus Contour electrode to ensure correct position and minimal insertion trauma. The potential advantages of increased modiolar proximity of intracochlear multichannel electrode arrays are a reduction in stimulation thresholds, an increase in dynamic range and more localized neural excitation. This may improve speech perception and reduce power consumption. These advantages may be negated if increased intracochlear damage results from the method used to position the electrodes close to the modiolus. A review of the University of Melbourne Department of Otolaryngology experience with temporal bone safety studies using the Nucleus standard straight electrode array and a variety of perimodiolar electrode array designs; comparison with temporal bone insertion studies from other centres and postmortem histopathology studies reported in the literature. Review of our initial clinical experience using the Nucleus Contour electrode array. The nature of intracochlear damage resulting from electrode insertion trauma ranges from minor, localized, spiral ligament tear to diffuse organ of Corti disruption and osseous spiral lamina fracture. The type of damage depends on the mechanical characteristics of the electrode array, the stiffness, curvature and size of the electrode in relation to the scala, and the surgical technique. The narrow, flexible, straight arrays are the least traumatic. Pre-curved or stiffer arrays are associated with an incidence of basilar membrane perforation. The cochleostomy must be correctly sited in relation to the round window to ensure scala tympani insertion. A cochleostomy anterior to the round window rather than inferior may lead to scala media or scala vestibuli insertion. Proximity of electrodes to the modiolus can be achieved without intracochlear damage provided the electrode array is a free fit within the scala, of appropriate size and shape, and accurate scala tympani insertion is performed.

Electrodynamic Arrays Having Nanomaterial Electrodes

NASA Technical Reports Server (NTRS)

Trigwell, Steven (Inventor); Biris, Alexandru S. (Inventor); Calle, Carlos I. (Inventor)

2013-01-01

An electrodynamic array of conductive nanomaterial electrodes and a method of making such an electrodynamic array. In one embodiment, a liquid solution containing nanomaterials is deposited as an array of conductive electrodes on a substrate, including rigid or flexible substrates such as fabrics, and opaque or transparent substrates. The nanomaterial electrodes may also be grown in situ. The nanomaterials may include carbon nanomaterials, other organic or inorganic nanomaterials or mixtures.

Intracellular recording of action potentials by nanopillar electroporation.

PubMed

Xie, Chong; Lin, Ziliang; Hanson, Lindsey; Cui, Yi; Cui, Bianxiao

2012-02-12

Action potentials have a central role in the nervous system and in many cellular processes, notably those involving ion channels. The accurate measurement of action potentials requires efficient coupling between the cell membrane and the measuring electrodes. Intracellular recording methods such as patch clamping involve measuring the voltage or current across the cell membrane by accessing the cell interior with an electrode, allowing both the amplitude and shape of the action potentials to be recorded faithfully with high signal-to-noise ratios. However, the invasive nature of intracellular methods usually limits the recording time to a few hours, and their complexity makes it difficult to simultaneously record more than a few cells. Extracellular recording methods, such as multielectrode arrays and multitransistor arrays, are non-invasive and allow long-term and multiplexed measurements. However, extracellular recording sacrifices the one-to-one correspondence between the cells and electrodes, and also suffers from significantly reduced signal strength and quality. Extracellular techniques are not, therefore, able to record action potentials with the accuracy needed to explore the properties of ion channels. As a result, the pharmacological screening of ion-channel drugs is usually performed by low-throughput intracellular recording methods. The use of nanowire transistors, nanotube-coupled transistors and micro gold-spine and related electrodes can significantly improve the signal strength of recorded action potentials. Here, we show that vertical nanopillar electrodes can record both the extracellular and intracellular action potentials of cultured cardiomyocytes over a long period of time with excellent signal strength and quality. Moreover, it is possible to repeatedly switch between extracellular and intracellular recording by nanoscale electroporation and resealing processes. Furthermore, vertical nanopillar electrodes can detect subtle changes in action potentials induced by drugs that target ion channels.

Intracellular recording of action potentials by nanopillar electroporation

NASA Astrophysics Data System (ADS)

Xie, Chong; Lin, Ziliang; Hanson, Lindsey; Cui, Yi; Cui, Bianxiao

2012-03-01

Action potentials have a central role in the nervous system and in many cellular processes, notably those involving ion channels. The accurate measurement of action potentials requires efficient coupling between the cell membrane and the measuring electrodes. Intracellular recording methods such as patch clamping involve measuring the voltage or current across the cell membrane by accessing the cell interior with an electrode, allowing both the amplitude and shape of the action potentials to be recorded faithfully with high signal-to-noise ratios. However, the invasive nature of intracellular methods usually limits the recording time to a few hours, and their complexity makes it difficult to simultaneously record more than a few cells. Extracellular recording methods, such as multielectrode arrays and multitransistor arrays, are non-invasive and allow long-term and multiplexed measurements. However, extracellular recording sacrifices the one-to-one correspondence between the cells and electrodes, and also suffers from significantly reduced signal strength and quality. Extracellular techniques are not, therefore, able to record action potentials with the accuracy needed to explore the properties of ion channels. As a result, the pharmacological screening of ion-channel drugs is usually performed by low-throughput intracellular recording methods. The use of nanowire transistors, nanotube-coupled transistors and micro gold-spine and related electrodes can significantly improve the signal strength of recorded action potentials. Here, we show that vertical nanopillar electrodes can record both the extracellular and intracellular action potentials of cultured cardiomyocytes over a long period of time with excellent signal strength and quality. Moreover, it is possible to repeatedly switch between extracellular and intracellular recording by nanoscale electroporation and resealing processes. Furthermore, vertical nanopillar electrodes can detect subtle changes in action potentials induced by drugs that target ion channels.

Ion manipulation method and device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Gordon A.; Baker, Erin M.; Smith, Richard D.

2017-11-07

An ion manipulation method and device is disclosed. The device includes a pair of substantially parallel surfaces. An array of inner electrodes is contained within, and extends substantially along the length of, each parallel surface. The device includes a first outer array of electrodes and a second outer array of electrodes. Each outer array of electrodes is positioned on either side of the inner electrodes, and is contained within and extends substantially along the length of each parallel surface. A DC voltage is applied to the first and second outer array of electrodes. A RF voltage, with a superimposed electricmore » field, is applied to the inner electrodes by applying the DC voltages to each electrode. Ions either move between the parallel surfaces within an ion confinement area or along paths in the direction of the electric field, or can be trapped in the ion confinement area.« less

Ion manipulation device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Gordon A.; Baker, Erin M.; Smith, Richard D.

2018-05-08

An ion manipulation method and device is disclosed. The device includes a pair of substantially parallel surfaces. An array of inner electrodes is contained within, and extends substantially along the length of, each parallel surface. The device includes a first outer array of electrodes and a second outer array of electrodes. Each outer array of electrodes is positioned on either side of the inner electrodes, and is contained within and extends substantially along the length of each parallel surface. A DC voltage is applied to the first and second outer array of electrodes. A RF voltage, with a superimposed electricmore » field, is applied to the inner electrodes by applying the DC voltages to each electrode. Ions either move between the parallel surfaces within an ion confinement area or along paths in the direction of the electric field, or can be trapped in the ion confinement area.« less

Design, fabrication, and evaluation of on-chip micro-supercapacitors

NASA Astrophysics Data System (ADS)

Beidaghi, Majid; Chen, Wei; Wang, Chunlei

2011-06-01

Development of miniaturized electronic systems has stimulated the demand for miniaturized power sources that can be integrated into such systems. Among the different micro power sources micro electrochemical energy storage and conversion devices are particularly attractive because of their high efficiency and relatively high energy density. Electrochemical micro-capacitors or micro-supercapacitors offer higher power density compared to micro-batteries and micro-fuel cells. In this paper, development of on-chip micro-supercapacitors based on interdigitated C-MEMS electrode microarrays is introduced. C-MEMS electrodes are employed both as electrode material for electric double layer capacitor (EDLC) or as three dimensional (3D) current collectors of EDLC or pseudo-capacitive materials. Recent advancements in fabrication methods of C-MEMS based micro-supercapacitors are discussed and electrochemical properties of C-MEMS electrodes and it composites are reviewed.

Micro Slot Generation by μ-ED Milling

NASA Astrophysics Data System (ADS)

Dave, H. K.; Mayanak, M. K.; Rajpurohit, S. R.; Mathai, V. J.

2016-08-01

Micro electro discharge machining is one of the most widely used advanced micro machining technique owing to its capability to fabricate micro features on any electrically conductive materials irrespective of its material properties. Despite its wide acceptability, the process is always adversely affected by issues like wear that occurred on the tool electrode, which results into generation of inaccurate features. Micro ED milling, a process variant in which the tool electrode simultaneously rotated and scanned during machining, is reported to have high process efficiency for generation of 3D complicated shapes and features with relatively less electrode wear intensity. In the present study an attempt has been made to study the effect of two process parameters viz. capacitance and scanning speed of tool electrode on end wear that occurs on the tool electrode and overcut of micro slots generated by micro ED milling. The experiment has been conducted on Al 1100 alloy with tungsten electrode having diameter of 300 μm. Results suggest that wear on the tool electrode and overcut of the micro features generated are highly influenced by the level of the capacitance employed during machining. For the parameter usage employed for present study however, no significant effect of variation of scanning speed has been observed on both responses.

Retinal instrument

DOEpatents

Britton, Charles L; D& #x27; Urso, Brian R; Chaum, Edward; Simpson, John T; Baba, Justin S; Ericson, M. Nance; Warmack, Robert J

2013-04-23

In one embodiment, the present invention provides a method of removing scar tissue from an eye that includes inserting a device including an array of micro-rods into an eye, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature; contacting a scar tissue with the array of micro-rods; and removing the array of micro-rods and the scar tissue from the eye. In another embodiment, the present invention provides a medical device for engaging a tissue including and an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods that is connected to the cannula, wherein the sharp feature of the at least one micro-rod is angled from a plane that is normal to a face of the base of the array of glass micro-rods.

A 100 electrode intracortical array: structural variability.

PubMed

Campbell, P K; Jones, K E; Normann, R A

1990-01-01

A technique has been developed for fabricating three dimensional "hair brush" electrode arrays from monocrystalline silicon blocks. Arrays consist of a square pattern of 100 penetrating electrodes, with 400 microns interelectrode spacing. Each electrode is 1.5mm in length and tapers from about 100 microns at its base to a sharp point at the tip. The tips of each electrode are coated with platinum and the entire structure, with the exception of the tips, is insulated with polyimide. Electrical connection to selected electrodes is made by wire bonding polyimide insulated 25 microns diameter gold lead wires to bonding pads on the rear surface of the array. As the geometrical characteristics of the electrodes in such an aray will influence their electrical properties (such as impedance, capacitance, spreading resistance in an electrolyte, etc.) it is desirable that such an array have minimal variability in geometry from electrode to electrode. A study was performed to determine the geometrical variability resulting from our micromachining techniques. Measurements of the diameter of each of the 100 electrodes were made at various planes above the silicon substrate of the array. For the array that was measured, the standard deviation of the diameters was approximately 9% of the mean diameter near the tip, 8% near the middle, and 6% near the base. We describe fabrication techniques which should further reduce these variabilities.

Advances in Testing Techniques for Digital Microfluidic Biochips

PubMed Central

Shukla, Vineeta; Hussin, Fawnizu Azmadi; Hamid, Nor Hisham; Zain Ali, Noohul Basheer

2017-01-01

With the advancement of digital microfluidics technology, applications such as on-chip DNA analysis, point of care diagnosis and automated drug discovery are common nowadays. The use of Digital Microfluidics Biochips (DMFBs) in disease assessment and recognition of target molecules had become popular during the past few years. The reliability of these DMFBs is crucial when they are used in various medical applications. Errors found in these biochips are mainly due to the defects developed during droplet manipulation, chip degradation and inaccuracies in the bio-assay experiments. The recently proposed Micro-electrode-dot Array (MEDA)-based DMFBs involve both fluidic and electronic domains in the micro-electrode cell. Thus, the testing techniques for these biochips should be revised in order to ensure proper functionality. This paper describes recent advances in the testing technologies for digital microfluidics biochips, which would serve as a useful platform for developing revised/new testing techniques for MEDA-based biochips. Therefore, the relevancy of these techniques with respect to testing of MEDA-based biochips is analyzed in order to exploit the full potential of these biochips. PMID:28749411

Advances in Testing Techniques for Digital Microfluidic Biochips.

PubMed

Shukla, Vineeta; Hussin, Fawnizu Azmadi; Hamid, Nor Hisham; Zain Ali, Noohul Basheer

2017-07-27

With the advancement of digital microfluidics technology, applications such as on-chip DNA analysis, point of care diagnosis and automated drug discovery are common nowadays. The use of Digital Microfluidics Biochips (DMFBs) in disease assessment and recognition of target molecules had become popular during the past few years. The reliability of these DMFBs is crucial when they are used in various medical applications. Errors found in these biochips are mainly due to the defects developed during droplet manipulation, chip degradation and inaccuracies in the bio-assay experiments. The recently proposed Micro-electrode-dot Array (MEDA)-based DMFBs involve both fluidic and electronic domains in the micro-electrode cell. Thus, the testing techniques for these biochips should be revised in order to ensure proper functionality. This paper describes recent advances in the testing technologies for digital microfluidics biochips, which would serve as a useful platform for developing revised/new testing techniques for MEDA-based biochips. Therefore, the relevancy of these techniques with respect to testing of MEDA-based biochips is analyzed in order to exploit the full potential of these biochips.

Localization of dense intracranial electrode arrays using magnetic resonance imaging

PubMed Central

Doyle, Werner K.; Halgren, Eric; Carlson, Chad; Belcher, Thomas L.; Cash, Sydney S.; Devinsky, Orrin; Thesen, Thomas

2013-01-01

Intracranial electrode arrays are routinely used in the pre-surgical evaluation of patients with medically refractory epilepsy, and recordings from these electrodes have been increasingly employed in human cognitive neurophysiology due to their high spatial and temporal resolution. For both researchers and clinicians, it is critical to localize electrode positions relative to the subject-specific neuroanatomy. In many centers, a post-implantation MRI is utilized for electrode detection because of its higher sensitivity for surgical complications and the absence of radiation. However, magnetic susceptibility artifacts surrounding each electrode prohibit unambiguous detection of individual electrodes, especially those that are embedded within dense grid arrays. Here, we present an efficient method to accurately localize intracranial electrode arrays based on pre- and post-implantation MR images that incorporates array geometry and the individual's cortical surface. Electrodes are directly visualized relative to the underlying gyral anatomy of the reconstructed cortical surface of individual patients. Validation of this approach shows high spatial accuracy of the localized electrode positions (mean of 0.96 mm±0.81 mm for 271 electrodes across 8 patients). Minimal user input, short processing time, and utilization of radiation-free imaging are strong incentives to incorporate quantitatively accurate localization of intracranial electrode arrays with MRI for research and clinical purposes. Co-registration to a standard brain atlas further allows inter-subject comparisons and relation of intracranial EEG findings to the larger body of neuroimaging literature. PMID:22759995

Optimization of return electrodes in neurostimulating arrays

NASA Astrophysics Data System (ADS)

Flores, Thomas; Goetz, Georges; Lei, Xin; Palanker, Daniel

2016-06-01

Objective. High resolution visual prostheses require dense stimulating arrays with localized inputs of individual electrodes. We study the electric field produced by multielectrode arrays in electrolyte to determine an optimal configuration of return electrodes and activation sequence. Approach. To determine the boundary conditions for computation of the electric field in electrolyte, we assessed current dynamics using an equivalent circuit of a multielectrode array with interleaved return electrodes. The electric field modeled with two different boundary conditions derived from the equivalent circuit was then compared to measurements of electric potential in electrolyte. To assess the effect of return electrode configuration on retinal stimulation, we transformed the computed electric fields into retinal response using a model of neural network-mediated stimulation. Main results. Electric currents at the capacitive electrode-electrolyte interface redistribute over time, so that boundary conditions transition from equipotential surfaces at the beginning of the pulse to uniform current density in steady state. Experimental measurements confirmed that, in steady state, the boundary condition corresponds to a uniform current density on electrode surfaces. Arrays with local return electrodes exhibit improved field confinement and can elicit stronger network-mediated retinal response compared to those with a common remote return. Connecting local return electrodes enhances the field penetration depth and allows reducing the return electrode area. Sequential activation of the pixels in large monopolar arrays reduces electrical cross-talk and improves the contrast in pattern stimulation. Significance. Accurate modeling of multielectrode arrays helps optimize the electrode configuration to maximize the spatial resolution, contrast and dynamic range of retinal prostheses.

Comparative Analysis of Human and Rodent Brain Primary Neuronal Culture Spontaneous Activity Using Micro-Electrode Array Technology.

PubMed

Napoli, Alessandro; Obeid, Iyad

2016-03-01

Electrical activity in embryonic brain tissue has typically been studied using Micro Electrode Array (MEA) technology to make dozens of simultaneous recordings from dissociated neuronal cultures, brain stem cell progenitors, or brain slices from fetal rodents. Although these rodent neuronal primary culture electrical properties are mostly investigated, it has not been yet established to what extent the electrical characteristics of rodent brain neuronal cultures can be generalized to those of humans. A direct comparison of spontaneous spiking activity between rodent and human primary neurons grown under the same in vitro conditions using MEA technology has never been carried out before and will be described in the present study. Human and rodent dissociated fetal brain neuronal cultures were established in-vitro by culturing on a glass grid of 60 planar microelectrodes neurons under identical conditions. Three different cultures of human neurons were produced from tissue sourced from a single aborted fetus (at 16-18 gestational weeks) and these were compared with seven different cultures of embryonic rat neurons (at 18 gestational days) originally isolated from a single rat. The results show that the human and rodent cultures behaved significantly differently. Whereas the rodent cultures demonstrated robust spontaneous activation and network activity after only 10 days, the human cultures required nearly 40 days to achieve a substantially weaker level of electrical function. These results suggest that rat neuron preparations may yield inferences that do not necessarily transfer to humans. © 2015 Wiley Periodicals, Inc.

Composite Biomarkers Derived from Micro-Electrode Array Measurements and Computer Simulations Improve the Classification of Drug-Induced Channel Block.

PubMed

Tixier, Eliott; Raphel, Fabien; Lombardi, Damiano; Gerbeau, Jean-Frédéric

2017-01-01

The Micro-Electrode Array (MEA) device enables high-throughput electrophysiology measurements that are less labor-intensive than patch-clamp based techniques. Combined with human-induced pluripotent stem cells cardiomyocytes (hiPSC-CM), it represents a new and promising paradigm for automated and accurate in vitro drug safety evaluation. In this article, the following question is addressed: which features of the MEA signals should be measured to better classify the effects of drugs? A framework for the classification of drugs using MEA measurements is proposed. The classification is based on the ion channels blockades induced by the drugs. It relies on an in silico electrophysiology model of the MEA, a feature selection algorithm and automatic classification tools. An in silico model of the MEA is developed and is used to generate synthetic measurements. An algorithm that extracts MEA measurements features designed to perform well in a classification context is described. These features are called composite biomarkers. A state-of-the-art machine learning program is used to carry out the classification of drugs using experimental MEA measurements. The experiments are carried out using five different drugs: mexiletine, flecainide, diltiazem, moxifloxacin, and dofetilide. We show that the composite biomarkers outperform the classical ones in different classification scenarios. We show that using both synthetic and experimental MEA measurements improves the robustness of the composite biomarkers and that the classification scores are increased.

A Step Closer to Membrane Protein Multiplexed Nanoarrays Using Biotin-Doped Polypyrrole

PubMed Central

2015-01-01

Whether for fundamental biological research or for diagnostic and drug discovery applications, protein micro- and nanoarrays are attractive technologies because of their low sample consumption, high-throughput, and multiplexing capabilities. However, the arraying platforms developed so far are still not able to handle membrane proteins, and specific methods to selectively immobilize these hydrophobic and fragile molecules are needed to understand their function and structural complexity. Here we integrate two technologies, electropolymerization and amphipols, to demonstrate the electrically addressable functionalization of micro- and nanosurfaces with membrane proteins. Gold surfaces are selectively modified by electrogeneration of a polymeric film in the presence of biotin, where avidin conjugates can then be selectively immobilized. The method is successfully applied to the preparation of protein-multiplexed arrays by sequential electropolymerization and biomolecular functionalization steps. The surface density of the proteins bound to the electrodes can be easily tuned by adjusting the amount of biotin deposited during electropolymerization. Amphipols are specially designed amphipathic polymers that provide a straightforward method to stabilize and add functionalities to membrane proteins. Exploiting the strong affinity of biotin for streptavidin, we anchor distinct membrane proteins onto different electrodes via a biotin-tagged amphipol. Antibody-recognition events demonstrate that the proteins are stably immobilized and that the electrodeposition of polypyrrole films bearing biotin units is compatible with the protein-binding activity. Since polypyrrole films show good conductivity properties, the platform described here is particularly well suited to prepare electronically transduced bionanosensors. PMID:24476392

Developing Barbed Microtip-Based Electrode Arrays for Biopotential Measurement

PubMed Central

Hsu, Li-Sheng; Tung, Shu-Wei; Kuo, Che-Hsi; Yang, Yao-Joe

2014-01-01

This study involved fabricating barbed microtip-based electrode arrays by using silicon wet etching. KOH anisotropic wet etching was employed to form a standard pyramidal microtip array and HF/HNO3 isotropic etching was used to fabricate barbs on these microtips. To improve the electrical conductance between the tip array on the front side of the wafer and the electrical contact on the back side, a through-silicon via was created during the wet etching process. The experimental results show that the forces required to detach the barbed microtip arrays from human skin, a polydimethylsiloxane (PDMS) polymer, and a polyvinylchloride (PVC) film were larger compared with those required to detach microtip arrays that lacked barbs. The impedances of the skin-electrode interface were measured and the performance levels of the proposed dry electrode were characterized. Electrode prototypes that employed the proposed tip arrays were implemented. Electroencephalogram (EEG) and electrocardiography (ECG) recordings using these electrode prototypes were also demonstrated. PMID:25014098

Bioelectrocatalytic application of titania nanotube array for molecule detection.

PubMed

Xie, Yibing; Zhou, Limin; Huang, Haitao

2007-06-15

A bioelectrocatalysis system based on titania nanotube electrode has been developed for the quantitative detection application. Highly ordered titania nanotube array with inner diameter of 60 nm and total length of 540 nm was formed by anodizing titanium foils. The functionalization modification was achieved by embedding glucose oxidases inside tubule channels and electropolymerizing pyrrole for interfacial immobilization. Morphology and microstructure characterization, electrochemical properties and bioelectrocatalytic reactivities of this composite were fully investigated. The direct detection of hydrogen peroxide by electrocatalytic reduction reaction was fulfilled on pure titania nanotube array with a detection limit up to 2.0 x 10(-4)mM. A biosensor based on the glucose oxidase-titania/titanium electrode was constructed for amperometric detection and quantitative determination of glucose in a phosphate buffer solution (pH 6.8) under a potentiostatic condition (-0.4V versus SCE). The resulting glucose biosensor showed an excellent performance with a response time below 5.6s and a detection limit of 2.0 x 10(-3)mM. The corresponding detection sensitivity was 45.5 microA mM(-1)cm(-2). A good operational reliability was also achieved with relative standard deviations below 3.0%. This novel biosensor exhibited quite high response sensitivity and low detection limit for potential applications.

Matrix-assisted energy conversion in nanostructured piezoelectric arrays

DOEpatents

Sirbuly, Donald J.; Wang, Xianying; Wang, Yinmin

2013-01-01

A nanoconverter is capable of directly generating electricity through a nanostructure embedded in a polymer layer experiencing differential thermal expansion in a stress transfer zone. High surface-to-volume ratio semiconductor nanowires or nanotubes (such as ZnO, silicon, carbon, etc.) are grown either aligned or substantially vertically aligned on a substrate. The resulting nanoforest is then embedded with the polymer layer, which transfers stress to the nanostructures in the stress transfer zone, thereby creating a nanostructure voltage output due to the piezoelectric effect acting on the nanostructure. Electrodes attached at both ends of the nanostructures generate output power at densities of .about.20 nW/cm.sup.2 with heating temperatures of .about.65.degree. C. Nanoconverters arrayed in a series parallel arrangement may be constructed in planar, stacked, or rolled arrays to supply power to nano- and micro-devices without use of external batteries.

Nanoband array electrode as a platform for high sensitivity enzyme-based glucose biosensing.

PubMed

Falk, Magnus; Sultana, Reshma; Swann, Marcus J; Mount, Andrew R; Freeman, Neville J

2016-12-01

We describe a novel glucose biosensor based on a nanoband array electrode design, manufactured using standard semiconductor processing techniques, and bio-modified with glucose oxidase immobilized at the nanoband electrode surface. The nanoband array architecture allows for efficient diffusion of glucose and oxygen to the electrode, resulting in a thousand-fold improvement in sensitivity and wide linear range compared to a conventional electrode. The electrode constitutes a robust and manufacturable sensing platform. Copyright © 2016 Elsevier B.V. All rights reserved.

In vitro biocompatibility and electrical stability of thick-film platinum/gold alloy electrodes printed on alumina

NASA Astrophysics Data System (ADS)

Carnicer-Lombarte, Alejandro; Lancashire, Henry T.; Vanhoestenberghe, Anne

2017-06-01

Objective. High-density electrode arrays are a powerful tool in both clinical neuroscience and basic research. However, current manufacturing techniques require the use of specialised techniques and equipment, which are available to few labs. We have developed a high-density electrode array with customisable design, manufactured using simple printing techniques and with commercially available materials. Approach. Electrode arrays were manufactured by thick-film printing a platinum-gold alloy (Pt/Au) and an insulating dielectric on 96% alumina ceramic plates. Arrays were conditioned in serum and serum-free conditions, with and without 1 kHz, 200 µA, charge balanced stimulation for up to 21 d. Array biocompatibility was assessed using an extract assay and a PC-12 cell contact assay. Electrode impedance, charge storage capacity and charge injection capacity were before and after array conditioning. Main results. The manufactured Pt/Au electrodes have a highly porous surface and exhibit electrical properties comparable to arrays manufactured using alternative techniques. Materials used in array manufacture were found to be non-toxic to L929 fibroblasts by extract assay, and neuronal-like PC-12 cells adhered and extended neurites on the array surfaces. Arrays remained functional after long-term delivery of electrical pulses while exposed to protein-rich environments. Charge storage capacities and charge injection capacities increased following stimulation accounted for by an increase in surface index (real surface area) observed by vertical scanning interferometry. Further, we observed accumulation of proteins at the electrode sites following conditioning in the presence of serum. Significance. This study demonstrates the in vitro biocompatibility of commercially available thick-film printing materials. The printing technique is both simple and versatile, with layouts readily modified to produce customized electrode arrays. Thick-film electrode arrays are an attractive tool that may be implemented for general tissue engineering and neuroscience research.

Vacuum chamber for ion manipulation device

DOEpatents

Chen, Tsung-Chi; Tang, Keqi; Ibrahim, Yehia M; Smith, Richard D; Anderson, Gordon A; Baker, Erin M

2014-12-09

An ion manipulation method and device is disclosed. The device includes a pair of substantially parallel surfaces. An array of inner electrodes is contained within, and extends substantially along the length of, each parallel surface. The device includes a first outer array of electrodes and a second outer array of electrodes. Each outer array of electrodes is positioned on either side of the inner electrodes, and is contained within and extends substantially along the length of each parallel surface. A DC voltage is applied to the first and second outer array of electrodes. A RF voltage, with a superimposed electric field, is applied to the inner electrodes by applying the DC voltages to each electrode. Ions either move between the parallel surfaces within an ion confinement area or along paths in the direction of the electric field, or can be trapped in the ion confinement area. A predetermined number of pairs of surfaces are disposed in one or more chambers, forming a multiple-layer ion mobility cyclotron device.

A novel bio-mimicking, planar nano-edge microelectrode enables enhanced long-term neural recording

NASA Astrophysics Data System (ADS)

Wijdenes, Pierre; Ali, Hasan; Armstrong, Ryden; Zaidi, Wali; Dalton, Colin; Syed, Naweed I.

2016-10-01

Our inability to accurately monitor individual neurons and their synaptic activity precludes fundamental understanding of brain function under normal and various pathological conditions. However, recent breakthroughs in micro- and nano-scale fabrication processes have advanced the development of neuro-electronic hybrid technology. Among such devices are three-dimensional and planar electrodes, offering the advantages of either high fidelity or longer-term recordings respectively. Here, we present the next generation of planar microelectrode arrays with “nano-edges” that enable long-term (≥1 month) and high fidelity recordings at a resolution 15 times higher than traditional planar electrodes. This novel technology enables better understanding of brain function and offers a tremendous opportunity towards the development of future bionic hybrids and drug discovery devices.

Fabrication and evaluation of an improved polymer-based cochlear electrode array for atraumatic insertion.

PubMed

Gwon, Tae Mok; Min, Kyou Sik; Kim, Jin Ho; Oh, Seung Ha; Lee, Ho Sun; Park, Min-Hyun; Kim, Sung June

2015-04-01

An atraumatic cochlear electrode array has become indispensable to high-performance cochlear implants such as electric acoustic stimulation (EAS), wherein the preservation of residual hearing is significant. For an atraumatic implantation, we propose and demonstrate a new improved design of a cochlear electrode array based on liquid crystal polymer (LCP), which can be fabricated by precise batch processes and a thermal lamination process, in contrast to conventional wire-based cochlear electrode arrays. Using a thin-film process of LCP-film-mounted silicon wafer and thermal press lamination, we devise a multi-layered structure with variable layers of LCP films to achieve a sufficient degree of basal rigidity and a flexible tip. A peripheral blind via and self-aligned silicone elastomer molding process can reduce the width of the array. Measuring the insertion and extraction forces in a human scala tympani model, we investigate five human temporal bone insertion trials and record electrically evoked auditory brainstem responses (EABR) acutely in a guinea pig model. The diameters of the finalized electrode arrays are 0.3 mm (tip) and 0.75 mm (base). The insertion force with a displacement of 8 mm from a round window and the maximum extraction force are 2.4 mN and 34.0 mN, respectively. The electrode arrays can be inserted from 360° to 630° without trauma at the basal turn. The EABR data confirm the efficacy of the array. A new design of LCP-based cochlear electrode array for atraumatic implantation is fabricated. Verification indicates that foretells the development of an atraumatic cochlear electrode array and clinical implant.

A Flexible Base Electrode Array for Intraspinal Microstimulation

PubMed Central

Khaled, I.; Elmallah, S.; Cheng, C.; Moussa, W.A.; Mushahwar, V.K.; Elias, A.L.

2013-01-01

In this paper, we report the development of a flexible base array of penetrating electrodes which can be used to interface with the spinal cord. A customizable and feasible fabrication protocol is described. The flexible base arrays were fabricated and implanted into surrogate cords which were elongated by 12%. The resulting strains were optically measured across the cord and compared to those associated with two types of electrodes arrays (one without a base and one with a rigid base connecting the electrodes). The deformation behavior of cords implanted with the flexible base arrays resembled the behavior of cords implanted with individual microwires that were not connected through a base. The results of the strain test were used to validate a 2D finite element model. The validated model was used to assess the stresses induced by the electrodes of the 3 types of arrays on the cord, and to examine how various design parameters (thickness, base modulus, etc.) impact the mechanical behavior of the electrode array. Rigid base arrays induced higher stresses on the cord than the flexible base arrays which in turn imposed higher stresses than the individual microwire implants. The developed flexible base array showed improvement over the rigid base array; however, its stiffness needs to be further reduced to emulate the mechanical behavior of individual microwire arrays without a base. PMID:23744656

Cochlear's unique electrode portfolio now and in the future.

PubMed

von Wallenberg, E; Briggs, R

2014-05-01

To review Cochlear's electrode portfolio and discuss the merits of current and future straight and perimodiolar electrode arrays. To present an update on implant reliability. Performance and hearing preservation data from studies involving the Slim Straight (CI422), Hybrid L24 and Contour Advance electrode array were reviewed. While several studies in past found little difference in performance outcomes between subjects implanted with perimodiolar and straight arrays, recent studies demonstrated that proximity to the modiolus is correlated with better performance. Hearing threshold increase was lowest with the Hybrid L24, closely followed by the slim straight array and was largest with the Contour Advance array. The CI24RE receiver-stimulator used for the three arrays had a cumulative survival of 99% at eight years post implantation. Combining the hearing preservation benefits of slim straight arrays with perimodiolar proximity is the design objective of Cochlear's next generation electrodes.

Electrophysiologic studies of neronal activities under ischemia condition.

PubMed

Huang, Shun-Ho; Wang, Ping-Hsien; Chen, Jia-Jin Jason

2008-01-01

Substrate with integrated microelectrode arrays (MEAs) provides an alternative electrophysiological method. With MEAS, one can measure the impedance and elicit electrical stimulation from multiple sites of MEAs to determine the electrophysiological conditions of cells. The aims of this research were to construct an impedance and action potential measurement system for neurons cultured on MEAs for observing the electrophysiological signal transmission in neuronal network during glucose and oxygen deprivation (OGD). An extracellular stimulator producing the biphasic micro-current pulse for neuron stimulation was built in this study. From the time-course recording of impedance, OGD condition effectively induced damage in neurons in vitro. It is known that the results of cell stimulation are affected by electrode impedance, so does the result of neuron cells covered on the electrode can measure the sealing resistance. For extracellular stimulation study, cortical neuronal activity was recorded and the suitable stimulation window was determined. However, the stimulation results were affected by electrode impedance as well as sealing impedance resulting from neuron cells covering the electrode. Further development of surface modification for cultured neuron network should provide a better way for in vitro impedance and electrophysiological measurements.

Ion manipulation device with electrical breakdown protection

DOEpatents

Chen, Tsung-Chi; Tang, Keqi; Ibrahim, Yehia M; Smith, Richard D; Anderson, Gordon A; Baker, Erin M

2014-12-02

An ion manipulation method and device is disclosed. The device includes a pair of substantially parallel surfaces. An array of inner electrodes is contained within, and extends substantially along the length of, each parallel surface. The device includes a first outer array of electrodes and a second outer array of electrodes. Each outer array of electrodes is positioned on either side of the inner electrodes, and is contained within and extends substantially along the length of each parallel surface. A DC voltage is applied to the first and second outer array of electrodes. A RF voltage, with a superimposed electric field, is applied to the inner electrodes by applying the DC voltages to each electrode. Ions either move between the parallel surfaces within an ion confinement area or along paths in the direction of the electric field, or can be trapped in the ion confinement area. The surfaces are housed in a chamber, and at least one electrically insulative shield is coupled to an inner surface of the chamber for increasing a mean-free-path between two adjacent electrodes in the chamber.

Micromachined devices for interfacing neurons

NASA Astrophysics Data System (ADS)

Stieglitz, Thomas; Beutel, Hansjoerg; Blau, Cornelia; Meyer, Joerg-Uwe

1998-07-01

Micromachining technologies were established to fabricate microelectrode arrays and devices for interfacing parts of the central or peripheral nervous system. The devices were part of a neural prosthesis that allows simultaneous multichannel recording and multisite stimulation of neurons. Overcoming the brittle mechanics of silicon devices and challenging housing demands close to the nerve we established a process technology to fabricate light-weighted and highly flexible polyimide based devices. Platinum and iridium thin-film electrodes were embedded in the polyimide. With reactive ion etching we got the possibility to simply integrate interconnections and to form nearly arbitrary outer shapes of the devices. We designed multichannel devices with up to 24 electrodes in the shape of plates, hooks and cuffs for different applications. In vitro tests exhibited stable electrode properties and no cytotoxicity of the materials and the devices. Sieve electrodes were chronically implanted in rats to interface the regenerating sciatic nerve. After six months, recordings and stimulation of the nerve via electrodes on the micro-device proved functional reinnervation of the limb. Concentric circular structures were designed for a retina implant for the blind. In preliminary studies in rabbits, evoked potentials in the visual cortex corresponded to stimulation sites of the implant.

Modiolus-Hugging Intracochlear Electrode Array with Shape Memory Alloy

PubMed Central

Min, Kyou Sik; Lim, Yoon Seob; Park, Se-Ik; Kim, Sung June

2013-01-01

In the cochlear implant system, the distance between spiral ganglia and the electrodes within the volume of the scala tympani cavity significantly affects the efficiency of the electrical stimulation in terms of the threshold current level and spatial selectivity. Because the spiral ganglia are situated inside the modiolus, the central axis of the cochlea, it is desirable that the electrode array hugs the modiolus to minimize the distance between the electrodes and the ganglia. In the present study, we propose a shape-memory-alloy-(SMA-) embedded intracochlear electrode which gives a straight electrode a curved modiolus-hugging shape using the restoration force of the SMA as triggered by resistive heating after insertion into the cochlea. An eight-channel ball-type electrode array is fabricated with an embedded titanium-nickel SMA backbone wire. It is demonstrated that the electrode array changes its shape in a transparent plastic human cochlear model. To verify the safe insertion of the electrode array into the human cochlea, the contact pressures during insertion at the electrode tip and the contact pressures over the electrode length after insertion were calculated using a 3D finite element analysis. The results indicate that the SMA-embedded electrode is functionally and mechanically feasible for clinical applications. PMID:23762181

Improved 2-D resistivity imaging of features in covered karst terrain with arrays of implanted electrodes

NASA Astrophysics Data System (ADS)

Kiflu, H. G.; Kruse, S. E.; Harro, D.; Loke, M. H.; Wilkinson, P. B.

2013-12-01

Electrical resistivity tomography is commonly used to identify geologic features associated with sinkhole formation. In covered karst terrain, however, it can be difficult to resolve the depth to top of limestone with this method. This is due to the fact that array lengths, and hence depth of resolution, are often limited by residential or commercial lot dimensions in urban environments. Furthermore, the sediments mantling the limestone are often clay-rich and highly conductive. The resistivity method has limited sensitivity to resistive zones beneath conductive zones. This sensitivity can be improved significantly with electrodes implanted at depth in the cover sediments near the top of limestone. An array of deep electrodes is installed with direct push technology in the karst cover. When combined with a surface array in which each surface electrode is underlain by a deep electrode, the array geometry is similar to a borehole array turned on its side. This method, called the Multi-Electrode Resistivity Implant Technique (MERIT), offers the promise of significantly improved resolution of epikarst and cover collapse development zones in the overlying sediment, the limestone or at the sediment-bedrock interface in heterogeneous karst environments. With a non-traditional array design, the question of optimal array geometries arises. Optimizing array geometries is complicated by the fact that many plausible 4-electrode readings will produce negative apparent resistivity values, even in homogeneous terrain. Negative apparent resistivities cannot be used in inversions based on the logarithm of the apparent resistivity. New algorithms for seeking optimal array geometries have been developed by modifying the 'Compare R' method of Wilkinson and Loke. The optimized arrays show significantly improved resolution over basic arrays adapted from traditional 2D surface geometries. Several MERIT case study surveys have been conducted in covered karst in west-central Florida, with 28-electrode arrays with electrodes 2-5 meters apart, and the deep arrays buried at 4-8 meters depth. Ground penetrating radar surveys, SPT borings and coring data provide selected 'ground truthing'. The case studies show that inclusion of the deep electrode array permits karst features such as undulations at the top of limestone and raveling zones within surficial sediments to be imaged. These features are not accessible from surface arrays with equivalent surface footprints. The method also has better resolution at depth at the ends of the lines, where surface arrays are typically plotted with a trapezoidal truncation due to poor resolution at the lower corners of the profile.

Electrostatic coalescence system with independent AC and DC hydrophilic electrodes

DOEpatents

Hovarongkura, A. David; Henry, Jr., Joseph D.

1981-01-01

An improved electrostatic coalescence system is provided in which independent AC and DC hydrophilic electrodes are employed to provide more complete dehydration of an oil emulsion. The AC field is produced between an AC electrode array and the water-oil interface wherein the AC electrode array is positioned parallel to the interface which acts as a grounded electrode. The emulsion is introduced into the AC field in an evenly distributed manner at the interface. The AC field promotes drop-drop and drop-interface coalescence of the water phase in the entering emulsion. The continuous oil phase passes upward through the perforated AC electrode array and enters a strong DC field produced between closely spaced DC electrodes in which small dispersed droplets of water entrained in the continuous phase are removed primarily by collection at hydrophilic DC electrodes. Large droplets of water collected by the electrodes migrate downward through the AC electrode array to the interface. All phase separation mechanisms are utilized to accomplish more complete phase separation.

Scalar localization of the electrode array after cochlear implantation: clinical experience using 64-slice multidetector computed tomography.

PubMed

Lane, John I; Witte, Robert J; Driscoll, Colin L W; Shallop, Jon K; Beatty, Charles W; Primak, Andrew N

2007-08-01

To use the improved resolution available with 64-slice multidetector computed tomography (MDCT) in vivo to localize the cochlear implant electrode array within the basal turn. Sixty-four-slice MDCT examinations of the temporal bones were retrospectively reviewed in 17 patients. Twenty-three implants were evaluated. Tertiary referral facility. All patients with previous cochlear implantation evaluated at our center between January 2004 and March 2006 were offered a computed tomographic examination as part of the study. In addition, preoperative computed tomographic examinations in patients being evaluated for a second bilateral device were included. Sixty-four-slice MDCT examination of the temporal bones. Localization of the electrode array within the basal turn from multiplanar reconstructions of the cochlea. Twenty-three implants were imaged in 17 patients. We were able to localize the electrode array within the scala tympani within the basal turn in 10 implants. In 3 implants, the electrode array was localized to the scala vestibuli. Migration of the electrode array from scala tympani to scala vestibuli was observed in three implants. Of the 7 implants in which localization of the electrode array was indeterminate, all had disease entities that obscured the definition of the normal cochlear anatomy. Sixty-four-slice MDCT with multiplanar reconstructions of the postoperative cochlea after cochlear implantation allows for accurate localization of the electrode array within the basal turn where normal cochlear anatomy is not obscured by the underlying disease process. Correlating the position of the electrode in the basal turn with surgical technique and implant design could be helpful in improving outcomes.

A multichannel scala tympani electrode array incorporating a drug delivery system for chronic intracochlear infusion.

PubMed

Shepherd, Robert K; Xu, Jin

2002-10-01

We have developed a novel scala tympani electrode array suitable for use in experimental animals. A unique feature of this array is its ability to chronically deliver pharmacological agents to the scala tympani. The design of the electrode array is described in detail. Experimental studies performed in guinea pigs confirm that this array can successfully deliver various drugs to the cochlea while chronically stimulating the auditory nerve.

Novel design and fabrication of a microcentrifuge for biomedical and biochemical applications

NASA Astrophysics Data System (ADS)

Yan, Dong; Xu, Bai; Castracane, James

2003-01-01

In this paper, modeling and simulation of a novel micro-centrifuge for biomedical and biochemical applications is described. The micro-centrifuge that we designed can work not only as a shaker but also as a detector of cell growth, which has great potential applications in bioanalysis. The initial design contains four channels for mixing or collecting of samples by centrifugal force. The rotor, the key component of this device, is actuated using electrostatic force. There are four electrodes on the substrate to actuate the micro-centrifuge rotation around the X-axis (lateral in plane) and the Y-axis (vertical in plane) respectively, and eight pairs of comb drives are used to actuate the micro-centrifuge rotation around the Z-axis (perpendicular to the XY plane). The multiple axis actuation design makes it very flexible to control the micro-centrifuge. Because of its small feature size, the cost of the reagent used for the micro-centrifuge will be greatly reduced. An array of micro-centrifuges will be designed to achieve a fast cycling time. A Finite Element Analysis (FEA) has been completed to analyze the static and dynamic performance of the micro-centrifuge, such as the natural frequencies, tilt angle, and driving voltage. A novel fabrication process using SOI technology has been proposed which is now being developed.

Fabrication of nano-gap electrode arrays by the construction and selective chemical etching of nano-crosswire stacks

NASA Technical Reports Server (NTRS)

Prokopuk, Nicholas (Inventor); Son, Kyung-Ah (Inventor)

2008-01-01

Methods of fabricating nano-gap electrode structures in array configurations, and the structures so produced. The fabrication method involves depositing first and second pluralities of electrodes comprising nanowires using processes such as lithography, deposition of metals, lift-off processes, and chemical etching that can be performed using conventional processing tools applicable to electronic materials processing. The gap spacing in the nano-gap electrode array is defined by the thickness of a sacrificial spacer layer that is deposited between the first and second pluralities of electrodes. The sacrificial spacer layer is removed by etching, thereby leaving a structure in which the distance between pairs of electrodes is substantially equal to the thickness of the sacrificial spacer layer. Electrode arrays with gaps measured in units of nanometers are produced. In one embodiment, the first and second pluralities of electrodes are aligned in mutually orthogonal orientations.

Microfabrication of IPMC cilia for bio-inspired flow sensing

NASA Astrophysics Data System (ADS)

Lei, Hong; Li, Wen; Tan, Xiaobo

2012-04-01

As the primary flow sensing organ for fishes, the lateral line system plays a critical role in fish behavior. Analogous to its biological counterpart, an artificial lateral line system, consisting of arrays of micro flow sensors, is expected to be instrumental in the navigation and control of underwater robots. In this paper we investigate the microfabrication of ionic polymer-metal composite (IPMC) cilia for the purpose of flow sensing. While existing macro- and microfabrication methods for IPMCs have predominantly focused on planar structures, we propose a device where micro IPMC beams stand upright on a substrate to effectively interact with the flow. Challenges in the casting of 3D Nafion structure and selective formation of electrodes are discussed, and potential solutions for addressing these challenges are presented together with preliminary microfabrication results.

Influence of geometry on the electrochemical response of carbon interdigitated microelectrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kostecki, R.; Song, X.Y.; Kinoshita, K.

2000-05-01

Microelectrodes were fabricated by carbonizing photoresist (700--1,000 C) that was patterned on a Si wafer by use of a mask and UV photolithography. Two geometric designs of interdigitated carbon microelectrodes were produced with dimensions of about 500 {micro}m length and 50 {micro}m width. The carbon structures were characterized by Raman spectroscopy, atomic force microscopy, and optical microscopy. The electrochemical response of the microelectrodes was investigated by cyclic voltammetry using the I{sub 3}{sup {minus}}/I{sup {minus}} redox couple. The collection efficiencies of carbon inderdigitated array electrodes (IDAEs) varied from 59 to 90% depending on the cell size, geometry, and generator-collector arrangement. Thesemore » collection efficiencies are comparable to those reported with multiband (n > 25 bands) IDAEs.« less

Direct laser-patterned micro-supercapacitors from paintable MoS2 films.

PubMed

Cao, Liujun; Yang, Shubin; Gao, Wei; Liu, Zheng; Gong, Yongji; Ma, Lulu; Shi, Gang; Lei, Sidong; Zhang, Yunhuai; Zhang, Shengtao; Vajtai, Robert; Ajayan, Pulickel M

2013-09-09

Micrometer-sized electrochemical capacitors have recently attracted attention due to their possible applications in micro-electronic devices. Here, a new approach to large-scale fabrication of high-capacitance, two-dimensional MoS2 film-based micro-supercapacitors is demonstrated via simple and low-cost spray painting of MoS2 nanosheets on Si/SiO2 chip and subsequent laser patterning. The obtained micro-supercapacitors are well defined by ten interdigitated electrodes (five electrodes per polarity) with 4.5 mm length, 820 μm wide for each electrode, 200 μm spacing between two electrodes and the thickness of electrode is ∼0.45 μm. The optimum MoS2 -based micro-supercapacitor exhibits excellent electrochemical performance for energy storage with aqueous electrolytes, with a high area capacitance of 8 mF cm(-2) (volumetric capacitance of 178 F cm(-3) ) and excellent cyclic performance, superior to reported graphene-based micro-supercapacitors. This strategy could provide a good opportunity to develop various micro-/nanosized energy storage devices to satisfy the requirements of portable, flexible, and transparent micro-electronic devices. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Tandem array of nanoelectronic readers embedded coplanar to a fluidic nanochannel for correlated single biopolymer analysis

PubMed Central

Lesser-Rojas, Leonardo; Sriram, K. K.; Liao, Kuo-Tang; Lai, Shui-Chin; Kuo, Pai-Chia; Chu, Ming-Lee; Chou, Chia-Fu

2014-01-01

We have developed a two-step electron-beam lithography process to fabricate a tandem array of three pairs of tip-like gold nanoelectronic detectors with electrode gap size as small as 9 nm, embedded in a coplanar fashion to 60 nm deep, 100 nm wide, and up to 150 μm long nanochannels coupled to a world-micro-nanofluidic interface for easy sample introduction. Experimental tests with a sealed device using DNA-protein complexes demonstrate the coplanarity of the nanoelectrodes to the nanochannel surface. Further, this device could improve transverse current detection by correlated time-of-flight measurements of translocating samples, and serve as an autocalibrated velocimeter and nanoscale tandem Coulter counters for single molecule analysis of heterogeneous samples. PMID:24753731

Investigation of Implantable Multi-Channel Electrode Array in Rat Cerebral Cortex Used for Recording

NASA Astrophysics Data System (ADS)

Taniguchi, Noriyuki; Fukayama, Osamu; Suzuki, Takafumi; Mabuchi, Kunihiko

There have recently been many studies concerning the control of robot movements using neural signals recorded from the brain (usually called the Brain-Machine interface (BMI)). We fabricated implantable multi-electrode arrays to obtain neural signals from the rat cerebral cortex. As any multi-electrode array should have electrode alignment that minimizes invasion, it is necessary to customize the recording site. We designed three types of 22-channel multi-electrode arrays, i.e., 1) wide, 2) three-layered, and 3) separate. The first extensively covers the cerebral cortex. The second has a length of 2 mm, which can cover the area of the primary motor cortex. The third array has a separate structure, which corresponds to the position of the forelimb and hindlimb areas of the primary motor cortex. These arrays were implanted into the cerebral cortex of a rat. We estimated the walking speed from neural signals using our fabricated three-layered array to investigate its feasibility for BMI research. The neural signal of the rat and its walking speed were simultaneously recorded. The results revealed that evaluation using either the anterior electrode group or posterior group provided accurate estimates. However, two electrode groups around the center yielded poor estimates although it was possible to record neural signals.

Analytical and numerical solutions of the potential and electric field generated by different electrode arrays in a tumor tissue under electrotherapy.

PubMed

Bergues Pupo, Ana E; Reyes, Juan Bory; Bergues Cabrales, Luis E; Bergues Cabrales, Jesús M

2011-09-24

Electrotherapy is a relatively well established and efficient method of tumor treatment. In this paper we focus on analytical and numerical calculations of the potential and electric field distributions inside a tumor tissue in a two-dimensional model (2D-model) generated by means of electrode arrays with shapes of different conic sections (ellipse, parabola and hyperbola). Analytical calculations of the potential and electric field distributions based on 2D-models for different electrode arrays are performed by solving the Laplace equation, meanwhile the numerical solution is solved by means of finite element method in two dimensions. Both analytical and numerical solutions reveal significant differences between the electric field distributions generated by electrode arrays with shapes of circle and different conic sections (elliptic, parabolic and hyperbolic). Electrode arrays with circular, elliptical and hyperbolic shapes have the advantage of concentrating the electric field lines in the tumor. The mathematical approach presented in this study provides a useful tool for the design of electrode arrays with different shapes of conic sections by means of the use of the unifying principle. At the same time, we verify the good correspondence between the analytical and numerical solutions for the potential and electric field distributions generated by the electrode array with different conic sections.

Label-free voltammetric detection of MicroRNAs at multi-channel screen printed array of electrodes comparison to graphite sensors.

PubMed

Erdem, Arzum; Congur, Gulsah

2014-01-01

The multi-channel screen-printed array of electrodes (MUX-SPE16) was used in our study for the first time for electrochemical monitoring of nucleic acid hybridization related to different miRNA sequences (miRNA-16, miRNA-15a and miRNA-660, i.e, the biomarkers for Alzheimer disease). The MUX-SPE16 was also used for the first time herein for the label-free electrochemical detection of nucleic acid hybridization combined magnetic beads (MB) assay in comparison to the disposable pencil graphite electrode (PGE). Under the principle of the magnetic beads assay, the biotinylated inosine substituted DNA probe was firstly immobilized onto streptavidin coated MB, and then, the hybridization process between probe and its complementary miRNA sequence was performed at MB surface. The voltammetric transduction was performed using differential pulse voltammetry (DPV) technique in combination with the single-use graphite sensor technologies; PGE and MUX-SPE16 for miRNA detection by measuring the guanine oxidation signal without using any external indicator. The features of single-use sensor technologies, PGE and MUX-SPE16, were discussed concerning to their reproducibility, detection limit, and selectivity compared to the results in the earlier studies presenting the electrochemical miRNA detection related to different miRNA sequences. © 2013 Elsevier B.V. All rights reserved.

Optimal Control of Shock Wave Turbulent Boundary Layer Interactions Using Micro-Array Actuation

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Tinapple, Jon; Surber, Lewis

2006-01-01

The intent of this study on micro-array flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to determine optimal designs of micro-array actuation for controlling the shock wave turbulent boundary layer interactions within supersonic inlets and compare these concepts to conventional bleed performance. The term micro-array refers to micro-actuator arrays which have heights of 25 to 40 percent of the undisturbed supersonic boundary layer thickness. This study covers optimal control of shock wave turbulent boundary layer interactions using standard micro-vane, tapered micro-vane, and standard micro-ramp arrays at a free stream Mach number of 2.0. The effectiveness of the three micro-array devices was tested using a shock pressure rise induced by the 10 shock generator, which was sufficiently strong as to separate the turbulent supersonic boundary layer. The overall design purpose of the micro-arrays was to alter the properties of the supersonic boundary layer by introducing a cascade of counter-rotating micro-vortices in the near wall region. In this manner, the impact of the shock wave boundary layer (SWBL) interaction on the main flow field was minimized without boundary bleed.

Electric crosstalk impairs spatial resolution of multi-electrode arrays in retinal implants

NASA Astrophysics Data System (ADS)

Wilke, R. G. H.; Khalili Moghadam, G.; Lovell, N. H.; Suaning, G. J.; Dokos, S.

2011-08-01

Active multi-electrode arrays are used in vision prostheses, including optic nerve cuffs and cortical and retinal implants for stimulation of neural tissue. For retinal implants, arrays with up to 1500 electrodes are used in clinical trials. The ability to convey information with high spatial resolution is critical for these applications. To assess the extent to which spatial resolution is impaired by electric crosstalk, finite-element simulation of electric field distribution in a simplified passive tissue model of the retina is performed. The effects of electrode size, electrode spacing, distance to target cells, and electrode return configuration (monopolar, tripolar, hexagonal) on spatial resolution is investigated in the form of a mathematical model of electric field distribution. Results show that spatial resolution is impaired with increased distance from the electrode array to the target cells. This effect can be partly compensated by non-monopolar electrode configurations and larger electrode diameters, albeit at the expense of lower pixel densities due to larger covering areas by each stimulation electrode. In applications where multi-electrode arrays can be brought into close proximity to target cells, as presumably with epiretinal implants, smaller electrodes in monopolar configuration can provide the highest spatial resolution. However, if the implantation site is further from the target cells, as is the case in suprachoroidal approaches, hexagonally guarded electrode return configurations can convey higher spatial resolution. This paper was originally submitted for the special issue containing contributions from the Sixth Biennial Research Congress of The Eye and the Chip.

Cochlear pathology following reimplantation of a multichannel scala tympani electrode array in the macaque.

PubMed

Shepherd, R K; Clark, G M; Xu, S A; Pyman, B C

1995-03-01

The histopathologic consequence of removing and reimplanting intracochlear electrode arrays on residual auditory nerve fibers is an important issue when evaluating the safety of cochlear prostheses. The authors have examined this issue by implanting multichannel intracochlear electrodes in macaque monkeys. Macaques were selected because of the similarity of the surgical technique used to insert electrodes into the cochlea compared to that in humans, in particular the ability to insert the arrays into the upper basal turn. Five macaques were bilaterally implanted with the Melbourne/Cochlear banded electrode array. Following a minimum implant period of 5 months, the electrode array on one side of each animal was removed and another immediately implanted. The animals were sacrificed a minimum of 5 months following the reinsertion procedure, and the cochleas prepared for histopathologic analysis. Long-term implantation of the electrode resulted in a relatively mild tissue response within the cochlea. Results also showed that inner and outer hair cell survival, although significantly reduced adjacent to the array, was normal in 8 of the 10 cochleas apicalward. Moreover, the electrode reinsertion procedure did not appear to adversely affect this apical hair cell population. Significant new bone formation was frequently observed in both control and reimplanted cochleas close to the electrode fenestration site and was associated with trauma to the endosteum and/or the introduction of bone chips into the cochlea at the time of surgery. Electrode insertion trauma, involving the osseous spiral lamina or basilar membrane, was more commonly observed in reimplanted cochleas. This damage was usually restricted to the lower basal turn and resulted in a more extensive ganglion cell loss. Finally, in a number of cochleas part of the electrode array was located within the scala media or scala vestibuli. These electrodes did not appear to evoke a more extensive tissue response or result in more extensive neural degeneration compared with electrodes located within the scala tympani. In conclusion, the present study has shown that the reimplantation of a multichannel scala, tympani electrode array can be achieved with minimal damage to the majority of cochlear structures. Increased insertion trauma, resulting in new bone formation and spiral ganglion cell loss, can occur in the lower basal turn in cases where the electrode entry point is difficult to identify due to proliferation of granulation and fibrous tissue.

Added clinical value of the inferior temporal EEG electrode chain.

PubMed

Bach Justesen, Anders; Eskelund Johansen, Ann Berit; Martinussen, Noomi Ida; Wasserman, Danielle; Terney, Daniella; Meritam, Pirgit; Gardella, Elena; Beniczky, Sándor

2018-01-01

To investigate the diagnostic added value of supplementing the 10-20 EEG array with six electrodes in the inferior temporal chain. EEGs were recorded with 25 electrodes: 19 positions of the 10-20 system, and six additional electrodes in the inferior temporal chain (F9/10, T9/10, P9/10). Five-hundred consecutive standard and sleep EEG recordings were reviewed using the 10-20 array and the extended array. We identified the recordings with EEG abnormalities that had peak negativities at the inferior temporal electrodes, and those that only were visible at the inferior temporal electrodes. From the 286 abnormal recordings, the peak negativity was at the inferior temporal electrodes in 81 cases (28.3%) and only visible at the inferior temporal electrodes in eight cases (2.8%). In the sub-group of patients with temporal abnormalities (n = 134), these represented 59% (peak in the inferior chain) and 6% (only seen at the inferior chain). Adding six electrodes in the inferior temporal electrode chain to the 10-20 array improves the localization and identification of EEG abnormalities, especially those located in the temporal region. Our results suggest that inferior temporal electrodes should be added to the EEG array, to increase the diagnostic yield of the recordings. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Artificial fish skin of self-powered micro-electromechanical systems hair cells for sensing hydrodynamic flow phenomena.

PubMed

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Miao, Jianmin; Warkiani, Majid Ebrahimi; Triantafyllou, Michael S

2015-10-06

Using biological sensors, aquatic animals like fishes are capable of performing impressive behaviours such as super-manoeuvrability, hydrodynamic flow 'vision' and object localization with a success unmatched by human-engineered technologies. Inspired by the multiple functionalities of the ubiquitous lateral-line sensors of fishes, we developed flexible and surface-mountable arrays of micro-electromechanical systems (MEMS) artificial hair cell flow sensors. This paper reports the development of the MEMS artificial versions of superficial and canal neuromasts and experimental characterization of their unique flow-sensing roles. Our MEMS flow sensors feature a stereolithographically fabricated polymer hair cell mounted on Pb(Zr(0.52)Ti(0.48))O3 micro-diaphragm with floating bottom electrode. Canal-inspired versions are developed by mounting a polymer canal with pores that guide external flows to the hair cells embedded in the canal. Experimental results conducted employing our MEMS artificial superficial neuromasts (SNs) demonstrated a high sensitivity and very low threshold detection limit of 22 mV/(mm s(-1)) and 8.2 µm s(-1), respectively, for an oscillating dipole stimulus vibrating at 35 Hz. Flexible arrays of such superficial sensors were demonstrated to localize an underwater dipole stimulus. Comparative experimental studies revealed a high-pass filtering nature of the canal encapsulated sensors with a cut-off frequency of 10 Hz and a flat frequency response of artificial SNs. Flexible arrays of self-powered, miniaturized, light-weight, low-cost and robust artificial lateral-line systems could enhance the capabilities of underwater vehicles. © 2015 The Author(s).

Artificial fish skin of self-powered micro-electromechanical systems hair cells for sensing hydrodynamic flow phenomena

PubMed Central

Asadnia, Mohsen; Kottapalli, Ajay Giri Prakash; Miao, Jianmin; Warkiani, Majid Ebrahimi; Triantafyllou, Michael S.

2015-01-01

Using biological sensors, aquatic animals like fishes are capable of performing impressive behaviours such as super-manoeuvrability, hydrodynamic flow ‘vision’ and object localization with a success unmatched by human-engineered technologies. Inspired by the multiple functionalities of the ubiquitous lateral-line sensors of fishes, we developed flexible and surface-mountable arrays of micro-electromechanical systems (MEMS) artificial hair cell flow sensors. This paper reports the development of the MEMS artificial versions of superficial and canal neuromasts and experimental characterization of their unique flow-sensing roles. Our MEMS flow sensors feature a stereolithographically fabricated polymer hair cell mounted on Pb(Zr0.52Ti0.48)O3 micro-diaphragm with floating bottom electrode. Canal-inspired versions are developed by mounting a polymer canal with pores that guide external flows to the hair cells embedded in the canal. Experimental results conducted employing our MEMS artificial superficial neuromasts (SNs) demonstrated a high sensitivity and very low threshold detection limit of 22 mV/(mm s−1) and 8.2 µm s−1, respectively, for an oscillating dipole stimulus vibrating at 35 Hz. Flexible arrays of such superficial sensors were demonstrated to localize an underwater dipole stimulus. Comparative experimental studies revealed a high-pass filtering nature of the canal encapsulated sensors with a cut-off frequency of 10 Hz and a flat frequency response of artificial SNs. Flexible arrays of self-powered, miniaturized, light-weight, low-cost and robust artificial lateral-line systems could enhance the capabilities of underwater vehicles. PMID:26423435

Preparation of Janus Particles and Alternating Current Electrokinetic Measurements with a Rapidly Fabricated Indium Tin Oxide Electrode Array.

PubMed

Chen, Yu-Liang; Jiang, Hong-Ren

2017-06-23

This article provides a simple method to prepare partially or fully coated metallic particles and to perform the rapid fabrication of electrode arrays, which can facilitate electrical experiments in microfluidic devices. Janus particles are asymmetric particles that contain two different surface properties on their two sides. To prepare Janus particles, a monolayer of silica particles is prepared by a drying process. Gold (Au) is deposited on one side of each particle using a sputtering device. The fully coated metallic particles are completed after the second coating process. To analyze the electrical surface properties of Janus particles, alternating current (AC) electrokinetic measurements, such as dielectrophoresis (DEP) and electrorotation (EROT)- which require specifically designed electrode arrays in the experimental device- are performed. However, traditional methods to fabricate electrode arrays, such as the photolithographic technique, require a series of complicated procedures. Here, we introduce a flexible method to fabricate a designed electrode array. An indium tin oxide (ITO) glass is patterned by a fiber laser marking machine (1,064 nm, 20 W, 90 to 120 ns pulse-width, and 20 to 80 kHz pulse repetition frequency) to create a four-phase electrode array. To generate the four-phase electric field, the electrodes are connected to a 2-channel function generator and to two invertors. The phase shift between the adjacent electrodes is set at either 90° (for EROT) or 180° (for DEP). Representative results of AC electrokinetic measurements with a four-phase ITO electrode array are presented.

Method for the electro-addressable functionalization of electrode arrays

DOEpatents

Harper, Jason C.; Polsky, Ronen; Dirk, Shawn M.; Wheeler, David R.; Arango, Dulce C.; Brozik, Susan M.

2015-12-15

A method for preparing an electrochemical biosensor uses bias-assisted assembly of unreactive -onium molecules on an electrode array followed by post-assembly electro-addressable conversion of the unreactive group to a chemical or biological recognition group. Electro-addressable functionalization of electrode arrays enables the multi-target electrochemical sensing of biological and chemical analytes.

Manufacture of high aspect ratio micro-pillar wall shear stress sensor arrays

NASA Astrophysics Data System (ADS)

Gnanamanickam, Ebenezer P.; Sullivan, John P.

2012-12-01

In the field of experimental fluid mechanics the measurement of unsteady, distributed wall shear stress has proved historically challenging. Recently, sensors based on an array of flexible micro-pillars have shown promise in carrying out such measurements. Similar sensors find use in other applications such as cellular mechanics. This work presents a manufacturing technique that can manufacture micro-pillar arrays of high aspect ratio. An electric discharge machine (EDM) is used to manufacture a micro-drilling tool. This micro-drilling tool is used to form holes in a wax sheet which acts as the mold for the micro-pillar array. Silicone rubber is cast in these molds to yield a micro-pillar array. Using this technique, micro-pillar arrays with a maximum aspect ratio of about 10 have been manufactured. Manufacturing issues encountered, steps to alleviate them and the potential of the process to manufacture similar micro-pillar arrays in a time-efficient manner are also discussed.

Tissue Damage, Temperature, and pH Induced by Different Electrode Arrays on Potato Pieces (Solanum tuberosum L.).

PubMed

González, Maraelys Morales; Aguilar, Claudia Hernández; Pacheco, Flavio Arturo Domínguez; Cabrales, Luis Enrique Bergues; Reyes, Juan Bory; Nava, Juan José Godina; Ambrosio, Paulo Eduardo; Domiguez, Dany Sanchez; Sierra González, Victoriano Gustavo; Pupo, Ana Elisa Bergues; Ciria, Héctor Manuel Camué; Alemán, Elizabeth Issac; García, Francisco Monier; Rivas, Clara Berenguer; Reina, Evelyn Chacón

2018-01-01

One of the most challenging problems of electrochemical therapy is the design and selection of suitable electrode array for cancer. The aim is to determine how two-dimensional spatial patterns of tissue damage, temperature, and pH induced in pieces of potato ( Solanum tuberosum L., var. Mondial) depend on electrode array with circular, elliptical, parabolic, and hyperbolic shape. The results show the similarity between the shapes of spatial patterns of tissue damage and electric field intensity, which, like temperature and pH take the same shape of electrode array. The adequate selection of suitable electrodes array requires an integrated analysis that involves, in a unified way, relevant information about the electrochemical process, which is essential to perform more efficiently way the therapeutic planning and the personalized therapy for patients with a cancerous tumor.

Phosphorization boosts the capacitance of mixed metal nanosheet arrays for high performance supercapacitor electrodes.

PubMed

Lan, Yingying; Zhao, Hongyang; Zong, Yan; Li, Xinghua; Sun, Yong; Feng, Juan; Wang, Yan; Zheng, Xinliang; Du, Yaping

2018-05-01

Binary transition metal phosphides hold immense potential as innovative electrode materials for constructing high-performance energy storage devices. Herein, porous binary nickel-cobalt phosphide (NiCoP) nanosheet arrays anchored on nickel foam (NF) were rationally designed as self-supported binder-free electrodes with high supercapacitance performance. Taking the combined advantages of compositional features and array architectures, the nickel foam supported NiCoP nanosheet array (NiCoP@NF) electrode possesses superior electrochemical performance in comparison with Ni-Co LDH@NF and NiCoO2@NF electrodes. The NiCoP@NF electrode shows an ultrahigh specific capacitance of 2143 F g-1 at 1 A g-1 and retained 1615 F g-1 even at 20 A g-1, showing excellent rate performance. Furthermore, a binder-free all-solid-state asymmetric supercapacitor device is designed, which exhibits a high energy density of 27 W h kg-1 at a power density of 647 W kg-1. The hierarchical binary nickel-cobalt phosphide nanosheet arrays hold great promise as advanced electrode materials for supercapacitors with high electrochemical performance.

Fabrication of a symmetric micro supercapacitor based on tubular ruthenium oxide on silicon 3D microstructures

NASA Astrophysics Data System (ADS)

Wang, Xiaofeng; Yin, Yajiang; Li, Xiangyu; You, Zheng

2014-04-01

A micro-supercapacitor with a three-dimensional configuration has been fabricated using an ICP etching technique. Hydrous ruthenium oxide with a tubular morphology is successfully synthesized using a cathodic deposition technique with a Si micro prominence as a template. The desired tubular RuO2·xH2O architecture facilitates electrolyte penetration and proton exchange/diffusion. A single MEMS electrode is studied using cyclic voltammetry, and a specific capacitance of 99.3 mF cm-2 and 70 F g-1 is presented at 5 mV s-1 in neutral Na2SO4 solution. The accelerated cycle life is tested at 80 mV s-1, and satisfactory cyclability is observed. When placed on a chip, the symmetric cell exhibits good supercapacitor properties, and a specific capacitance as high as 23 mF cm-2 is achieved at 10 mA cm-2. Therefore, 3D MEMS microelectrode arrays with electrochemically deposited ruthenium oxide films are promising candidates for on-chip electrochemical micro-capacitor applications.

High resolution micro-CT scanning as an innovative tool for evaluation of the surgical positioning of cochlear implant electrodes.

PubMed

Postnov, A; Zarowski, A; De Clerck, N; Vanpoucke, F; Offeciers, F E; Van Dyck, D; Peeters, S

2006-05-01

X-ray microtomography (micro-CT) is a new technique allowing for visualization of the internal structure of opaque specimens with a quasi-histological quality. Among multiple potential applications, the use of this technique in otology is very promising. Micro-CT appears to be ideally suited for in vitro visualization of the inner ear tissues as well as for evaluation of the electrode damage and/or surgical insertion trauma during implantation of the cochlear implant electrodes. This technique can greatly aid in design and development of new cochlear implant electrodes and is applicable for temporal bone studies. The main advantage of micro-CT is the practically artefact-free preparation of the samples and the possibility of evaluation of the interesting parameters along the whole insertion depth of the electrode. This paper presents the results of the first application of micro-CT for visualization of the inner ear structures in human temporal bones and for evaluation of the surgical positioning of the cochlear implant electrodes relative to the intracochlear soft tissues.

The standardized EEG electrode array of the IFCN.

PubMed

Seeck, Margitta; Koessler, Laurent; Bast, Thomas; Leijten, Frans; Michel, Christoph; Baumgartner, Christoph; He, Bin; Beniczky, Sándor

2017-10-01

Standardized EEG electrode positions are essential for both clinical applications and research. The aim of this guideline is to update and expand the unifying nomenclature and standardized positioning for EEG scalp electrodes. Electrode positions were based on 20% and 10% of standardized measurements from anatomical landmarks on the skull. However, standard recordings do not cover the anterior and basal temporal lobes, which is the most frequent source of epileptogenic activity. Here, we propose a basic array of 25 electrodes including the inferior temporal chain, which should be used for all standard clinical recordings. The nomenclature in the basic array is consistent with the 10-10-system. High-density scalp EEG arrays (64-256 electrodes) allow source imaging with even sub-lobar precision. This supplementary exam should be requested whenever necessary, e.g. search for epileptogenic activity in negative standard EEG or for presurgical evaluation. In the near future, nomenclature for high density electrodes arrays beyond the 10-10 system needs to be defined, to allow comparison and standardized recordings across centers. Contrary to the established belief that smaller heads needs less electrodes, in young children at least as many electrodes as in adults should be applied due to smaller skull thickness and the risk of spatial aliasing. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

Comparison of neural damage induced by electrical stimulation with faradaic and capacitor electrodes.

PubMed

McCreery, D B; Agnew, W F; Yuen, T G; Bullara, L A

1988-01-01

Arrays of platinum (faradaic) and anodized, sintered tantalum pentoxide (capacitor) electrodes were implanted bilaterally in the subdural space of the parietal cortex of the cat. Two weeks after implantation both types of electrodes were pulsed for seven hours with identical waveforms consisting of controlled-current, charge-balanced, symmetric, anodic-first pulse pairs, 400 microseconds/phase and a charge density of 80-100 microC/cm2 (microcoulombs per square cm) at 50 pps (pulses per second). One group of animals was sacrificed immediately following stimulation and a second smaller group one week after stimulation. Tissues beneath both types of pulsed electrodes were damaged, but the difference in damage for the two electrode types was not statistically significant. Tissue beneath unpulsed electrodes was normal. At the ultrastructural level, in animals killed immediately after stimulation, shrunken and hyperchromic neurons were intermixed with neurons showing early intracellular edema. Glial cells appeared essentially normal. In animals killed one week after stimulation most of the damaged neurons had recovered, but the presence of shrunken, vacuolated and degenerating neurons showed that some of the cells were damaged irreversibly. It is concluded that most of the neural damage from stimulations of the brain surface at the level used in this study derives from processes associated with passage of the stimulus current through tissue, such as neuronal hyperactivity rather than electrochemical reactions associated with current injection across the electrode-tissue interface, since such reactions occur only with the faradaic electrodes.

Recording and assessment of evoked potentials with electrode arrays.

PubMed

Miljković, N; Malešević, N; Kojić, V; Bijelić, G; Keller, T; Popović, D B

2015-09-01

In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.

Analytical and numerical solutions of the potential and electric field generated by different electrode arrays in a tumor tissue under electrotherapy

PubMed Central

2011-01-01

Background Electrotherapy is a relatively well established and efficient method of tumor treatment. In this paper we focus on analytical and numerical calculations of the potential and electric field distributions inside a tumor tissue in a two-dimensional model (2D-model) generated by means of electrode arrays with shapes of different conic sections (ellipse, parabola and hyperbola). Methods Analytical calculations of the potential and electric field distributions based on 2D-models for different electrode arrays are performed by solving the Laplace equation, meanwhile the numerical solution is solved by means of finite element method in two dimensions. Results Both analytical and numerical solutions reveal significant differences between the electric field distributions generated by electrode arrays with shapes of circle and different conic sections (elliptic, parabolic and hyperbolic). Electrode arrays with circular, elliptical and hyperbolic shapes have the advantage of concentrating the electric field lines in the tumor. Conclusion The mathematical approach presented in this study provides a useful tool for the design of electrode arrays with different shapes of conic sections by means of the use of the unifying principle. At the same time, we verify the good correspondence between the analytical and numerical solutions for the potential and electric field distributions generated by the electrode array with different conic sections. PMID:21943385

Manganese oxide micro-supercapacitors with ultra-high areal capacitance

NASA Astrophysics Data System (ADS)

Wang, Xu; Myers, Benjamin D.; Yan, Jian; Shekhawat, Gajendra; Dravid, Vinayak; Lee, Pooi See

2013-05-01

A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2.A symmetric micro-supercapacitor is constructed by electrochemically depositing manganese oxide onto micro-patterned current collectors. High surface-to-volume ratio of manganese oxide and short diffusion distance between electrodes give an ultra-high areal capacitance of 56.3 mF cm-2 at a current density of 27.2 μA cm-2. Electronic supplementary information (ESI) available: Experimental procedures; optical images of micro-supercapacitors; areal capacitances of samples M-0.3C, M-0.6C and M-0.9C; illustration of interdigital finger electrodes; Nyquist plot of Co(OH)2 deposited on micro-electrodes. See DOI: 10.1039/c3nr00210a

A simultaneous multichannel monophasic action potential electrode array for in vivo epicardial repolarization mapping.

PubMed

Sahakian, A V; Peterson, M S; Shkurovich, S; Hamer, M; Votapka, T; Ji, T; Swiryn, S

2001-03-01

While the recording of extracellular monophasic action potentials (MAPs) from single epicardial or endocardial sites has been performed for over a century, we are unaware of any previous successful attempt to record MAPs simultaneously from a large number of sites in vivo. We report here the design and validation of an array of MAP electrodes which records both depolarization and repolarization simultaneously at up to 16 epicardial sites in a square array on the heart in vivo. The array consists of 16 sintered Ag-AgCl electrodes mounted in a common housing with individual suspensions allowing each electrode to exert a controlled pressure on the epicardial surface. The electrodes are arranged in a square array, with each quadrant of four having an additional recessed sintered Ag-AgCl reference electrode at its center. A saline-soaked sponge establishes ionic contact between the reference electrodes and the tissue. The array was tested on six anesthetized open-chested pigs. Simultaneous diagnostic-quality MAP recordings were obtained from up to 13 out of 16 ventricular sites. Ventricular MAPs had amplitudes of 10-40 mV with uniform morphologies and stable baselines for up to 30 min. MAP duration at 90% repolarization was measured and shown to vary as expected with cycle length during sustained pacing. The relationship between MAP duration and effective refractory period was also confirmed. The ability of the array to detect local differences in repolarization was tested in two ways. Placement of the array straddling the atrioventricular (AV) junction yielded simultaneous atrial or ventricular recordings at corresponding sites during 1:1 and 2:1 AV conduction. Localized ischemia via constriction of a coronary artery branch resulted in shortening of the repolarization phase at the ischemic, but not the nonischemic, sites. In conclusion, these results indicate that the simultaneous multichannel MAP electrode array is a viable method for in vivo epicardial repolarization mapping. The array has the potential to be expanded to increase the number of sites and spatial resolution.

MANTA--an open-source, high density electrophysiology recording suite for MATLAB.

PubMed

Englitz, B; David, S V; Sorenson, M D; Shamma, S A

2013-01-01

The distributed nature of nervous systems makes it necessary to record from a large number of sites in order to decipher the neural code, whether single cell, local field potential (LFP), micro-electrocorticograms (μECoG), electroencephalographic (EEG), magnetoencephalographic (MEG) or in vitro micro-electrode array (MEA) data are considered. High channel-count recordings also optimize the yield of a preparation and the efficiency of time invested by the researcher. Currently, data acquisition (DAQ) systems with high channel counts (>100) can be purchased from a limited number of companies at considerable prices. These systems are typically closed-source and thus prohibit custom extensions or improvements by end users. We have developed MANTA, an open-source MATLAB-based DAQ system, as an alternative to existing options. MANTA combines high channel counts (up to 1440 channels/PC), usage of analog or digital headstages, low per channel cost (<$90/channel), feature-rich display and filtering, a user-friendly interface, and a modular design permitting easy addition of new features. MANTA is licensed under the GPL and free of charge. The system has been tested by daily use in multiple setups for >1 year, recording reliably from 128 channels. It offers a growing list of features, including integrated spike sorting, PSTH and CSD display and fully customizable electrode array geometry (including 3D arrays), some of which are not available in commercial systems. MANTA runs on a typical PC and communicates via TCP/IP and can thus be easily integrated with existing stimulus generation/control systems in a lab at a fraction of the cost of commercial systems. With modern neuroscience developing rapidly, MANTA provides a flexible platform that can be rapidly adapted to the needs of new analyses and questions. Being open-source, the development of MANTA can outpace commercial solutions in functionality, while maintaining a low price-point.

MANTA—an open-source, high density electrophysiology recording suite for MATLAB

PubMed Central

Englitz, B.; David, S. V.; Sorenson, M. D.; Shamma, S. A.

2013-01-01

The distributed nature of nervous systems makes it necessary to record from a large number of sites in order to decipher the neural code, whether single cell, local field potential (LFP), micro-electrocorticograms (μECoG), electroencephalographic (EEG), magnetoencephalographic (MEG) or in vitro micro-electrode array (MEA) data are considered. High channel-count recordings also optimize the yield of a preparation and the efficiency of time invested by the researcher. Currently, data acquisition (DAQ) systems with high channel counts (>100) can be purchased from a limited number of companies at considerable prices. These systems are typically closed-source and thus prohibit custom extensions or improvements by end users. We have developed MANTA, an open-source MATLAB-based DAQ system, as an alternative to existing options. MANTA combines high channel counts (up to 1440 channels/PC), usage of analog or digital headstages, low per channel cost (<$90/channel), feature-rich display and filtering, a user-friendly interface, and a modular design permitting easy addition of new features. MANTA is licensed under the GPL and free of charge. The system has been tested by daily use in multiple setups for >1 year, recording reliably from 128 channels. It offers a growing list of features, including integrated spike sorting, PSTH and CSD display and fully customizable electrode array geometry (including 3D arrays), some of which are not available in commercial systems. MANTA runs on a typical PC and communicates via TCP/IP and can thus be easily integrated with existing stimulus generation/control systems in a lab at a fraction of the cost of commercial systems. With modern neuroscience developing rapidly, MANTA provides a flexible platform that can be rapidly adapted to the needs of new analyses and questions. Being open-source, the development of MANTA can outpace commercial solutions in functionality, while maintaining a low price-point. PMID:23653593

Multi-scale recordings for neuroprosthetic control of finger movements.

PubMed

Baker, Justin; Bishop, William; Kellis, Spencer; Levy, Todd; House, Paul; Greger, Bradley

2009-01-01

We trained a rhesus monkey to perform individuated and combined finger flexions and extensions of the thumb, index, and middle finger. A Utah Electrode Array (UEA) was implanted into the hand region of the motor cortex contralateral to the monkey's trained hand. We also implanted a microwire electrocorticography grid (microECoG) epidurally so that it covered the UEA. The microECoG grid spanned the arm and hand regions of both the primary motor and somatosensory cortices. Previously this monkey had Implantable MyoElectric Sensors (IMES) surgically implanted into the finger muscles of the monkey's forearm. Action potentials (APs), local field potentials (LFPs), and microECoG signals were recorded from wired head-stage connectors for the UEA and microECoG grids, while EMG was recorded wirelessly. The monkey performed a finger flexion/extension task while neural and EMG data were acquired. We wrote an algorithm that uses the spike data from the UEA to perform a real-time decode of the monkey's finger movements. Also, analyses of the LFP and microECoG data indicate that these data show trial-averaged differences between different finger movements, indicating the data are potentially decodeable.

Stress testing of electrically active FlexMEAs with simultaneous electrical recording in fluidic environment: Introduction of a new measurement setup

NASA Astrophysics Data System (ADS)

Westerhausen, Markus; Martin, Tanja; Kappel, Marcel; Hofmann, Boris

2018-02-01

We present a measurement setup consisting of two fluid-filled pressure chambers to mimic the mechanical stress likely to that of small body movements on biomedical flexible micro-electrode arrays for the analysis of various degradation mechanisms. Our main goal was the simulation of micro-motions in fluid conditions, while maintaining an electric access to the device. These micro-motions would be likely to those occurring in the human body caused by the intracranial pressure in magnitudes of 7-25 mmHg, which translates to a fluid pressure of 9-33 mbar. Furthermore, severe mechanical stress can be administered to the samples under the previously mentioned environment. Therefore, a flexible, polyimide-based sample with various metal test structures was fabricated and analyzed in the presented measurement setup. A comparison of the elongation of the sample's surface as a function of the applied hydrostatic pressure is given with computer simulations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cela, Carlos Jose; Lazzi, Gianluca

The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power sourcemore » via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.« less

Selective wetting-induced micro-electrode patterning for flexible micro-supercapacitors.

PubMed

Kim, Sung-Kon; Koo, Hyung-Jun; Lee, Aeri; Braun, Paul V

2014-08-13

Selective wetting-induced micro-electrode patterning is used to fabricate flexible micro-supercapacitors (mSCs). The resulting mSCs exhibit high performance, mechanical stability, stable cycle life, and hold great promise for facile integration into flexible devices requiring on-chip energy storage. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Double-plasma enhanced carbon shield for spatial/interfacial controlled electrodes in lithium ion batteries via micro-sized silicon from wafer waste

NASA Astrophysics Data System (ADS)

Chen, Bing-Hong; Chuang, Shang-I.; Duh, Jenq-Gong

2016-11-01

Using spatial and interfacial control, the micro-sized silicon waste from wafer slurry could greatly increase its retention potential as a green resource for silicon-based anode in lithium ion batteries. Through step by step spatial and interfacial control for electrode, the cyclability of recycled waste gains potential performance from its original poor retention property. In the stages of spatial control, the electrode stabilizers of active, inactive and conductive additives were mixed into slurries for maintaining architecture and conductivity of electrode. In addition, a fusion electrode modification of interfacial control combines electrolyte additive, technique of double-plasma enhanced carbon shield (D-PECS) to convert the chemical bond states and to alter the formation of solid electrolyte interphases (SEIs) in the first cycle. The depth profiles of chemical composition from external into internal electrode illustrate that the fusion electrode modification not only forms a boundary to balance the interface between internal and external electrodes but also stabilizes the SEIs formation and soothe the expansion of micro-sized electrode. Through these effect approaches, the performance of micro-sized Si waste electrode can be boosted from its serious capacity degradation to potential retention (200 cycles, 1100 mAh/g) and better meet the requirements for facile and cost-effective in industrial production.

Tissue Damage, Temperature, and pH Induced by Different Electrode Arrays on Potato Pieces (Solanum tuberosum L.)

PubMed Central

González, Maraelys Morales; Aguilar, Claudia Hernández; Pacheco, Flavio Arturo Domínguez; Cabrales, Luis Enrique Bergues; Reyes, Juan Bory; Nava, Juan José Godina; Ambrosio, Paulo Eduardo; Domiguez, Dany Sanchez; Sierra González, Victoriano Gustavo; Pupo, Ana Elisa Bergues; Ciria, Héctor Manuel Camué; Alemán, Elizabeth Issac; García, Francisco Monier; Rivas, Clara Berenguer; Reina, Evelyn Chacón

2018-01-01

One of the most challenging problems of electrochemical therapy is the design and selection of suitable electrode array for cancer. The aim is to determine how two-dimensional spatial patterns of tissue damage, temperature, and pH induced in pieces of potato (Solanum tuberosum L., var. Mondial) depend on electrode array with circular, elliptical, parabolic, and hyperbolic shape. The results show the similarity between the shapes of spatial patterns of tissue damage and electric field intensity, which, like temperature and pH take the same shape of electrode array. The adequate selection of suitable electrodes array requires an integrated analysis that involves, in a unified way, relevant information about the electrochemical process, which is essential to perform more efficiently way the therapeutic planning and the personalized therapy for patients with a cancerous tumor. PMID:29725584

[Reliable fixation of cochlear implant electrode mountings in children and adults--initial experiences with a new titanium clip].

PubMed

Müller, J; Schön, F; Helms, J

1998-04-01

There is a reported 1% incidence of delayed migration of extrusions of the electrode arrays out of the cochlea. A titanium clip to fix the electrode array of the MED EL Combi 40 Cochlear Implant System is described. The clip is designed and shaped in a double U configuration. The clip material allows easy adaption to the individual anatomical situation. The clip is fixed to a bony bridge at the incus bar and fixes the electrode in a plane parallel to the chorda facial angle. It is closed around the electrode similarly to a stapes piston around the incus. Additional tests which examined the possible risk of damaging the electrode carrier and clinical findings are described. The clip was used in 23 cases with a follow-up period up to 1 year. No signs for dislocation of the electrode were found. In one revision case the clip was covered with a thin mucosal layer. The electrode array showed no signs of damage. Intraoperative findings confirmed the experimental tests on the electrode fixation. The titanium clip facilitates safe and quick fixation of the electrode array and prevents dislocation. its flexibility and shape minimizes the risk of damage.

Fabrication and characterization of three-dimensional carbon electrodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Teixidor, Genis Turon; Zaouk, Rabih B.; Park, Benjamin Y.; Madou, Marc J.

This paper presents fabrication and testing results of three-dimensional carbon anodes for lithium-ion batteries, which are fabricated through the pyrolysis of lithographically patterned epoxy resins. This technique, known as Carbon-MEMS, provides great flexibility and an unprecedented dimensional control in shaping carbon microstructures. Variations in the pattern density and in the pyrolysis conditions result in anodes with different specific and gravimetric capacities, with a three to six times increase in specific capacity with respect to the current thin-film battery technology. Newly designed cross-shaped Carbon-MEMS arrays have a much higher mechanical robustness (as given by their moment of inertia) than the traditionally used cylindrical posts, but the gravimetric analysis suggests that new designs with thinner features are required for better carbon utilization. Pyrolysis at higher temperatures and slower ramping up schedules reduces the irreversible capacity of the carbon electrodes. We also analyze the addition of Meso-Carbon Micro-Beads (MCMB) particles on the reversible and irreversible capacities of new three-dimensional, hybrid electrodes. This combination results in a slight increase in reversible capacity and a big increase in the irreversible capacity of the carbon electrodes, mostly due to the non-complete attachment of the MCMB particles.

JPRS Report, Science & Technology, China, High-Performance Computer Systems

DTIC Science & Technology

1992-10-28

microprocessor array The microprocessor array in the AP85 system is com- posed of 16 completely identical array element micro - processors . Each array element...microprocessors and capable of host machine reading and writing. The memory capacity of the array element micro - processors as a whole can be expanded...transmission functions to carry out data transmission from array element micro - processor to array element microprocessor, from array element

MEMS fabrication and frequency sweep for suspending beam and plate electrode in electrostatic capacitor

NASA Astrophysics Data System (ADS)

Zhu, Jianxiong; Song, Weixing

2018-01-01

We report a MEMS fabrication and frequency sweep for a high-order mode suspending beam and plate layer in electrostatic micro-gap semiconductor capacitor. This suspended beam and plate was designed with silicon oxide (SiO2) film which was fabricated using bulk silicon micromachining technology on both side of a silicon substrate. The designed semiconductor capacitors were driven by a bias direct current (DC) and a sweep frequency alternative current (AC) in a room temperature for an electrical response test. Finite element calculating software was used to evaluate the deformation mode around its high-order response frequency. Compared a single capacitor with a high-order response frequency (0.42 MHz) and a 1 × 2 array parallel capacitor, we found that the 1 × 2 array parallel capacitor had a broader high-order response range. And it concluded that a DC bias voltage can be used to modulate a high-order response frequency for both a single and 1 × 2 array parallel capacitors.

MnO 2 nanotube and nanowire arrays by electrochemical deposition for supercapacitors

NASA Astrophysics Data System (ADS)

Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li

Highly ordered MnO 2 nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO 2 nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO 2 nanotube array electrode has superior capacitive behaviour to that of the MnO 2 nanowire array electrode. In addition to high specific capacitance, the MnO 2 nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors.

Hierarchical Mesoporous Zinc-Nickel-Cobalt Ternary Oxide Nanowire Arrays on Nickel Foam as High-Performance Electrodes for Supercapacitors.

PubMed

Wu, Chun; Cai, Junjie; Zhang, Qiaobao; Zhou, Xiang; Zhu, Ying; Shen, Pei Kang; Zhang, Kaili

2015-12-09

Nickel foam supported hierarchical mesoporous Zn-Ni-Co ternary oxide (ZNCO) nanowire arrays are synthesized by a simple two-step approach including a hydrothermal method and subsequent calcination process and directly utilized for supercapacitive investigation for the first time. The nickel foam supported hierarchical mesoporous ZNCO nanowire arrays possess an ultrahigh specific capacitance value of 2481.8 F g(-1) at 1 A g(-1) and excellent rate capability of about 91.9% capacitance retention at 5 A g(-1). More importantly, an asymmetric supercapacitor with a high energy density (35.6 Wh kg(-1)) and remarkable cycle stability performance (94% capacitance retention over 3000 cycles) is assembled successfully by employing the ZNCO electrode as positive electrode and activated carbon as negative electrode. The remarkable electrochemical behaviors demonstrate that the nickel foam supported hierarchical mesoporous ZNCO nanowire array electrodes are highly desirable for application as advanced supercapacitor electrodes.

Facile synthesis of ultrathin manganese dioxide nanosheets arrays on nickel foam as advanced binder-free supercapacitor electrodes

NASA Astrophysics Data System (ADS)

Huang, Ming; Zhao, Xiao Li; Li, Fei; Zhang, Li Li; Zhang, Yu Xin

2015-03-01

Ultrathin MnO2 nanosheets arrays on Ni foam have been fabricated by a facile hydrothermal approach and further investigated as the binder-free electrode for high-performance supercapacitors. This unique well-designed binder-free electrode exhibits a high specific capacitance (595.2 F g-1 at a current density of 0.5 A g-1), good rate capability (64.1% retention), and excellent cycling stability (89% capacitance retention after 3000 cycles). Moreover, an asymmetric supercapacitor is constructed using the as-prepared MnO2 nanosheets arrays as the positive electrode and activated microwave exfoliated graphite oxide (MEGO) as the negative electrode. The optimized asymmetric supercapacitor displays excellent electrochemical performance with an energy density of 25.8 Wh kg-1 and a maximum power density of 223.2 kW kg-1. These impressive performances suggest that the MnO2 nanosheet array is a promising electrode material for supercapacitors.

Controlled Growth of Large-Area Aligned Single-Crystalline Organic Nanoribbon Arrays for Transistors and Light-Emitting Diodes Driving

NASA Astrophysics Data System (ADS)

Wang, Wei; Wang, Liang; Dai, Gaole; Deng, Wei; Zhang, Xiujuan; Jie, Jiansheng; Zhang, Xiaohong

2017-10-01

Organic field-effect transistors (OFETs) based on organic micro-/nanocrystals have been widely reported with charge carrier mobility exceeding 1.0 cm2 V-1 s-1, demonstrating great potential for high-performance, low-cost organic electronic applications. However, fabrication of large-area organic micro-/nanocrystal arrays with consistent crystal growth direction has posed a significant technical challenge. Here, we describe a solution-processed dip-coating technique to grow large-area, aligned 9,10-bis(phenylethynyl) anthracene (BPEA) and 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN) single-crystalline nanoribbon arrays. The method is scalable to a 5 × 10 cm2 wafer substrate, with around 60% of the wafer surface covered by aligned crystals. The quality of crystals can be easily controlled by tuning the dip-coating speed. Furthermore, OFETs based on well-aligned BPEA and TIPS-PEN single-crystalline nanoribbons were constructed. By optimizing channel lengths and using appropriate metallic electrodes, the BPEA and TIPS-PEN-based OFETs showed hole mobility exceeding 2.0 cm2 V-1 s-1 (average mobility 1.2 cm2 V-1 s-1) and 3.0 cm2 V-1 s-1 (average mobility 2.0 cm2 V-1 s-1), respectively. They both have a high on/off ratio ( I on/ I off) > 109. The performance can well satisfy the requirements for light-emitting diodes driving.

The use of hydrogel as an electrode-skin interface for electrode array FES applications.

PubMed

Cooper, Glen; Barker, Anthony T; Heller, Ben W; Good, Tim; Kenney, Laurence P J; Howard, David

2011-10-01

Functional electrical stimulation is commonly used to restore function in post-stroke patients in upper and lower limb applications. Location of the electrodes can be a problem hence some research groups have begun to experiment with electrode arrays. Electrode arrays are interfaced with a thin continuous hydrogel sheet which is high resistivity to reduce transverse currents between electrodes in the array. Research using electrode arrays has all been conducted in a laboratory environment over short time periods but it is suspected that this approach will not be feasible over longer time periods due to changes in hydrogel resistivity. High resistivity hydrogel samples were tested by leaving them in contact with the skin over a seven day period. The samples became extremely conductive with resistivities reaching around 10-50 Ωm. The effect of these resistivity changes was studied using finite element analysis to solve for the stationary current quasi-static electric field gradient in the tissue. Electrical stimulation efficiency and focality were calculated for both a high and low resistivity electrode-skin interface layer at different tissue depths. The results showed that low resistivity hydrogel produced significant decreases in stimulation efficiency and focality compared to high resistivity hydrogel. Copyright © 2011 IPEM. Published by Elsevier Ltd. All rights reserved.

Fabrication of polymer micro-lens array with pneumatically diaphragm-driven drop-on-demand inkjet technology.

PubMed

Xie, Dan; Zhang, Honghai; Shu, Xiayun; Xiao, Junfeng

2012-07-02

The paper reports an effective method to fabricate micro-lens arrays with the ultraviolet-curable polymer, using an original pneumatically diaphragm-driven drop-on-demand inkjet system. An array of plano convex micro-lenses can be formed on the glass substrate due to surface tension and hydrophobic effect. The micro-lens arrays have uniform focusing function, smooth and real planar surface. The fabrication process showed good repeatability as well, fifty micro-lenses randomly selected form 9 × 9 miro-lens array with an average diameter of 333.28μm showed 1.1% variations. Also, the focal length, the surface roughness and optical property of the fabricated micro-lenses are measured, analyzed and proved satisfactory. The technique shows great potential for fabricating polymer micro-lens arrays with high flexibility, simple technological process and low production cost.

Microfabricated linear Paul-Straubel ion trap

DOEpatents

Mangan, Michael A [Albuquerque, NM; Blain, Matthew G [Albuquerque, NM; Tigges, Chris P [Albuquerque, NM; Linker, Kevin L [Albuquerque, NM

2011-04-19

An array of microfabricated linear Paul-Straubel ion traps can be used for mass spectrometric applications. Each ion trap comprises two parallel inner RF electrodes and two parallel outer DC control electrodes symmetric about a central trap axis and suspended over an opening in a substrate. Neighboring ion traps in the array can share a common outer DC control electrode. The ions confined transversely by an RF quadrupole electric field potential well on the ion trap axis. The array can trap a wide array of ions.

Synthesis of molecular imprinted polymer modified TiO{sub 2} nanotube array electrode and their photoelectrocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu Na; Chen Shuo; Wang Hongtao

2008-10-15

A tetracycline hydrochloride (TC) molecularly imprinted polymer (MIP) modified TiO{sub 2} nanotube array electrode was prepared via surface molecular imprinting. Its surface was structured with surface voids and the nanotubes were open at top end with an average diameter of approximately 50 nm. The MIP-modified TiO{sub 2} nanotube array with anatase phase was identified by XRD and a distinguishable red shift in the absorption spectrum was observed. The MIP-modified electrode also exhibited a high adsorption capacity for TC due to its high surface area providing imprinted sites. Photocurrent was generated on the MIP-modified photoanode using the simulated solar spectrum andmore » increased with the increase of positive bias potential. Under simulated solar light irradiation, the MIP-modified TiO{sub 2} nanotube array electrode exhibited enhanced photoelectrocatalytic (PEC) activity with the apparent first-order rate constant being 1.2-fold of that with TiO{sub 2} nanotube array electrode. The effect of the thickness of the MIP layer on the PEC activity was also evaluated. - Graphical abstract: A tetracycline hydrochloride molecularly imprinted polymer modified TiO{sub 2} nanotube array electrode was prepared via surface molecular imprinting. It showed improved response to simulated solar light and higher adsorption capability for tetracycline hydrochloride, thereby exhibiting increased PEC activity under simulated solar light irradiation. The apparent first-order rate constant was 1.2-fold of that on TiO{sub 2} nanotube array electrode.« less

Spatiotemporal norepinephrine mapping using a high-density CMOS microelectrode array.

PubMed

Wydallis, John B; Feeny, Rachel M; Wilson, William; Kern, Tucker; Chen, Tom; Tobet, Stuart; Reynolds, Melissa M; Henry, Charles S

2015-10-21

A high-density amperometric electrode array containing 8192 individually addressable platinum working electrodes with an integrated potentiostat fabricated using Complementary Metal Oxide Semiconductor (CMOS) processes is reported. The array was designed to enable electrochemical imaging of chemical gradients with high spatiotemporal resolution. Electrodes are arranged over a 2 mm × 2 mm surface area into 64 subarrays consisting of 128 individual Pt working electrodes as well as Pt pseudo-reference and auxiliary electrodes. Amperometric measurements of norepinephrine in tissue culture media were used to demonstrate the ability of the array to measure concentration gradients in complex media. Poly(dimethylsiloxane) microfluidics were incorporated to control the chemical concentrations in time and space, and the electrochemical response at each electrode was monitored to generate electrochemical heat maps, demonstrating the array's imaging capabilities. A temporal resolution of 10 ms can be achieved by simultaneously monitoring a single subarray of 128 electrodes. The entire 2 mm × 2 mm area can be electrochemically imaged in 64 seconds by cycling through all subarrays at a rate of 1 Hz per subarray. Monitoring diffusional transport of norepinephrine is used to demonstrate the spatiotemporal resolution capabilities of the system.

Insertion characteristics and placement of the Mid-Scala electrode array in human temporal bones using detailed cone beam computed tomography.

PubMed

Dietz, Aarno; Gazibegovic, Dzemal; Tervaniemi, Jyrki; Vartiainen, Veli-Matti; Löppönen, Heikki

2016-12-01

The aim of this study was to evaluate the insertion results and placement of the new Advanced Bionics HiFocus Mid-Scala (HFms) electrode array, inserted through the round window membrane, in eight fresh human temporal bones using cone beam computed tomography (CBCT). Pre- and post-insertion CBCT scans were registered to create a 3D reconstruction of the cochlea with the array inserted. With an image fusion technique both the bony edges of the cochlea and the electrode array in situ could accurately be determined, thus enabling to identify the exact position of the electrode array within the scala tympani. Vertical and horizontal scalar location was measured at four points along the cochlea base at an angular insertion depth of 90°, 180° and 270° and at electrode 16, the most basal electrode. Smooth insertion through the round window membrane was possible in all temporal bones. The imaging results showed that there were no dislocations from the scala tympani into the scala vestibule. The HFms electrode was positioned in the middle of the scala along the whole electrode array in three out of the eight bones and in 62 % of the individual locations measured along the base of the cochlea. In only one cochlea a close proximity of the electrode with the basilar membrane was observed, indicating possible contact with the basilar membrane. The results and assessments presented in this study appear to be highly accurate. Although a further validation including histopathology is needed, the image fusion technique described in this study represents currently the most accurate method for intracochlear electrode assessment obtainable with CBCT.

An array of highly flexible electrodes with a tailored configuration locked by gelatin during implantation-initial evaluation in cortex cerebri of awake rats.

PubMed

Agorelius, Johan; Tsanakalis, Fotios; Friberg, Annika; Thorbergsson, Palmi T; Pettersson, Lina M E; Schouenborg, Jens

2015-01-01

A major challenge in the field of neural interfaces is to overcome the problem of poor stability of neuronal recordings, which impedes long-term studies of individual neurons in the brain. Conceivably, unstable recordings reflect relative movements between electrode and tissue. To address this challenge, we have developed a new ultra-flexible electrode array and evaluated its performance in awake non-restrained animals. An array of eight separated gold leads (4 × 10 μm), individually flexible in 3D, were cut from a gold sheet using laser milling and insulated with Parylene C. To provide structural support during implantation into rat cortex, the electrode array was embedded in a hard gelatin based material, which dissolves after implantation. Recordings were made during 3 weeks. At termination, the animals were perfused with fixative and frozen to prevent dislocation of the implanted electrodes. A thick slice of brain tissue, with the electrode array still in situ, was made transparent using methyl salicylate to evaluate the conformation of the implanted electrode array. Median noise levels and signal/noise remained relatively stable during the 3 week observation period; 4.3-5.9 μV and 2.8-4.2, respectively. The spike amplitudes were often quite stable within recording sessions and for 15% of recordings where single-units were identified, the highest-SNR unit had an amplitude higher than 150 μV. In addition, high correlations (>0.96) between unit waveforms recorded at different time points were obtained for 58% of the electrode sites. The structure of the electrode array was well preserved 3 weeks after implantation. A new implantable multichannel neural interface, comprising electrodes individually flexible in 3D that retain its architecture and functionality after implantation has been developed. Since the new neural interface design is adaptable, it offers a versatile tool to explore the function of various brain structures.

Microfabricated Ion Beam Drivers for Magnetized Target Fusion

NASA Astrophysics Data System (ADS)

Persaud, Arun; Seidl, Peter; Ji, Qing; Ardanuc, Serhan; Miller, Joseph; Lal, Amit; Schenkel, Thomas

2015-11-01

Efficient, low-cost drivers are important for Magnetized Target Fusion (MTF). Ion beams offer a high degree of control to deliver the required mega joules of driver energy for MTF and they can be matched to several types of magnetized fuel targets, including compact toroids and solid targets. We describe an ion beam driver approach based on the MEQALAC concept (Multiple Electrostatic Quadrupole Array Linear Accelerator) with many beamlets in an array of micro-fabricated channels. The channels consist of a lattice of electrostatic quadrupoles (ESQ) for focusing and of radio-frequency (RF) electrodes for ion acceleration. Simulations with particle-in-cell and beam envelope codes predict >10x higher current densities compared to state-of-the-art ion accelerators. This increase results from dividing the total ion beam current up into many beamlets to control space charge forces. Focusing elements can be biased taking advantage of high breakdown electric fields in sub-mm structures formed using MEMS techniques (Micro-Electro-Mechanical Systems). We will present results on ion beam transport and acceleration in MEMS based beamlets. Acknowledgments: This work is supported by the U.S. DOE under Contract No. DE-AC02-05CH11231.

Simulation analysis of rectifying microfluidic mixing with field-effect-tunable electrothermal induced flow.

PubMed

Liu, Weiyu; Ren, Yukun; Tao, Ye; Yao, Bobin; Li, You

2018-03-01

We report herein field-effect control on in-phase electrothermal streaming from a theoretical point of view, a phenomenon termed "alternating-current electrothermal-flow field effect transistor" (ACET-FFET), in the context of a new technology for handing analytes in microfluidics. Field-effect control through a gate terminal endows ACET-FFET the ability to generate arbitrary symmetry breaking in the transverse vortex flow pattern, which makes it attractive for mixing microfluidic samples. A computational model is developed to study the feasibility of this new microfluidic device design for micromixing. The influence of various parameters on developing an efficient mixer is investigated, and an integrated layout of discrete electrode array is suggested for achieving high-throughput mixing. Our physical demonstration with field-effect electrothermal flow control using a simple electrode structure proves invaluable for designing active micromixers for modern micro total analytical system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulations of induced-charge electro-osmosis in microfluidic devices

NASA Astrophysics Data System (ADS)

Ben, Yuxing

2005-03-01

Theories of nonlinear electrokinetic phenomena generally assume a uniform, neutral bulk electroylte in contact with a polarizable thin double layer near a metal or dielectric surface, which acts as a "capacitor skin". Induced-charge electro-osmosis (ICEO) is the general effect of nonlinear electro-osmotic slip, when an applied electric field acts on its own induced (diffuse) double-layer charge. In most theoretical and experimental work, ICEO has been studied in very simple geometries, such as colloidal spheres and planar, periodic micro-electrode arrays. Here we use finite-element simulations to predict how more complicated geometries of polarizable surfaces and/or electrodes yield flow profiles with subtle dependence on the amplitude and frequency of the applied voltage. We also consider how the simple model equations break down, due to surface conduction, bulk diffusion, and concentration polarization, for large applied voltages (as in most experiments).

Large-scale recording of neuronal ensembles.

PubMed

Buzsáki, György

2004-05-01

How does the brain orchestrate perceptions, thoughts and actions from the spiking activity of its neurons? Early single-neuron recording research treated spike pattern variability as noise that needed to be averaged out to reveal the brain's representation of invariant input. Another view is that variability of spikes is centrally coordinated and that this brain-generated ensemble pattern in cortical structures is itself a potential source of cognition. Large-scale recordings from neuronal ensembles now offer the opportunity to test these competing theoretical frameworks. Currently, wire and micro-machined silicon electrode arrays can record from large numbers of neurons and monitor local neural circuits at work. Achieving the full potential of massively parallel neuronal recordings, however, will require further development of the neuron-electrode interface, automated and efficient spike-sorting algorithms for effective isolation and identification of single neurons, and new mathematical insights for the analysis of network properties.

A Mid-scala Cochlear Implant Electrode Design Achieves a Stable Post-surgical Position in the Cochlea of Patients Over Time-A Prospective Observational Study.

PubMed

Dees, Guido; Smits, Jeroen Jules; Janssen, A Miranda L; Hof, Janny R; Gazibegovic, Dzemal; Hoof, Marc van; Stokroos, Robert J

2018-04-01

Cochlear implant (CI) electrode design impacts the clinical performance of patients. Stability and the occurrence of electrode array migration, which is the postoperative movement of the electrode array, were investigated using a mid-scalar electrode array and postoperative image analysis. A prospective observational study was conducted. A mid-scalar electrode was surgically placed using a mastoidectomy, followed by a posterior tympanotomy and an extended round-window or cochleostomy insertion. A few days after surgery and 3 months later Cone Beam Computed Tomography (CBCT) was performed. The two different CBCT's were fused, and the differences between the electrode positions in three dimensions were calculated (the migration). A migration greater than 0.5 mm was deemed clinically relevant. Fourteen subjects participated. The mid-scalar electrode migrated in one patient (7%). This did not lead to the extrusion of an electrode contact. The mean migration of every individual electrode contact in all patients was 0.36 mm (95% confidence interval 0.22-0.50 mm), which approximates to the estimated measurement error of the CBCT technique. A mid-scalar electrode array achieves a stable position in the cochlea in a small but representative group of patients. The methods applied in this work can be used for providing postoperative feedback for surgeons and for benchmarking electrode designs.

A frogspawn-inspired hierarchical porous NaTi2(PO4)3-C array for high-rate and long-life aqueous rechargeable sodium batteries

NASA Astrophysics Data System (ADS)

Zhao, Baidan; Lin, Bo; Zhang, Sen; Deng, Chao

2015-11-01

Hollow micro/nano-arrays have attracted tremendous attention in the field of energy conversion and storage, but such structures usually compromise the volumetric energy density of the electrode materials. Frogspawn consists of a spawn core and a transparent jelly shell organized in a hierarchical porous array, which exhibits superior mechanical strength and high-efficiency oxygen permeability. It can be used as a model for designing a new high-performance electrode material, which has advantages such as a high surface area, fast mass transport and superior durability. Herein, we report a frogspawn-like NaTi2(PO4)3/C array prepared by a facile preform impregnation strategy. The framework is formed by a hollow carbon sphere connected by the NaTi2(PO4)3/C skeleton, and its hollow is filled with the NaTi2(PO4)3 nanospheres. The whole hierarchical porous three-dimensional array copies the structure of a frogspawn. This unique structure not only enables easy electrolyte percolation and fast electron/ion transport, but also enhances the reversible capacity and cycling durability. When it is applied as an anode of the aqueous sodium ion battery, it exhibits favorable high rate capability and superior cycling stability, and retains 89% of the initial capacity after two thousand cycles at 20 C. Moreover, the full cell using the frogspawn-inspired NaTi2(PO4)3-C as the anode and Na0.44MnO2 as the cathode is capable of ultralong cycling up to one thousand cycles at alternate 10 and 60 C, which is among the best of state-of-the-art aqueous sodium ion systems. Therefore, the frogspawn-inspired architecture provides a new strategy to the tailored design of polyanion materials for high-power applications.Hollow micro/nano-arrays have attracted tremendous attention in the field of energy conversion and storage, but such structures usually compromise the volumetric energy density of the electrode materials. Frogspawn consists of a spawn core and a transparent jelly shell organized in a hierarchical porous array, which exhibits superior mechanical strength and high-efficiency oxygen permeability. It can be used as a model for designing a new high-performance electrode material, which has advantages such as a high surface area, fast mass transport and superior durability. Herein, we report a frogspawn-like NaTi2(PO4)3/C array prepared by a facile preform impregnation strategy. The framework is formed by a hollow carbon sphere connected by the NaTi2(PO4)3/C skeleton, and its hollow is filled with the NaTi2(PO4)3 nanospheres. The whole hierarchical porous three-dimensional array copies the structure of a frogspawn. This unique structure not only enables easy electrolyte percolation and fast electron/ion transport, but also enhances the reversible capacity and cycling durability. When it is applied as an anode of the aqueous sodium ion battery, it exhibits favorable high rate capability and superior cycling stability, and retains 89% of the initial capacity after two thousand cycles at 20 C. Moreover, the full cell using the frogspawn-inspired NaTi2(PO4)3-C as the anode and Na0.44MnO2 as the cathode is capable of ultralong cycling up to one thousand cycles at alternate 10 and 60 C, which is among the best of state-of-the-art aqueous sodium ion systems. Therefore, the frogspawn-inspired architecture provides a new strategy to the tailored design of polyanion materials for high-power applications. Electronic supplementary information (ESI) available: Lab-assembled preform impregnation system; EDX spectroscopy of the residual carbon matrix after HF treatment; atomic parameters and lattice parameters of the prepared array; crystal structural, morphological and physical characteristics of the reference samples, comparison of the electrochemical performance between the frogspawn-inspired array and the previously reported results. See DOI: 10.1039/c5nr06505d

A novel high electrode count spike recording array using an 81,920 pixel transimpedance amplifier-based imaging chip.

PubMed

Johnson, Lee J; Cohen, Ethan; Ilg, Doug; Klein, Richard; Skeath, Perry; Scribner, Dean A

2012-04-15

Microelectrode recording arrays of 60-100 electrodes are commonly used to record neuronal biopotentials, and these have aided our understanding of brain function, development and pathology. However, higher density microelectrode recording arrays of larger area are needed to study neuronal function over broader brain regions such as in cerebral cortex or hippocampal slices. Here, we present a novel design of a high electrode count picocurrent imaging array (PIA), based on an 81,920 pixel Indigo ISC9809 readout integrated circuit camera chip. While originally developed for interfacing to infrared photodetector arrays, we have adapted the chip for neuron recording by bonding it to microwire glass resulting in an array with an inter-electrode pixel spacing of 30 μm. In a high density electrode array, the ability to selectively record neural regions at high speed and with good signal to noise ratio are both functionally important. A critical feature of our PIA is that each pixel contains a dedicated low noise transimpedance amplifier (∼0.32 pA rms) which allows recording high signal to noise ratio biocurrents comparable to single electrode voltage amplifier recordings. Using selective sampling of 256 pixel subarray regions, we recorded the extracellular biocurrents of rabbit retinal ganglion cell spikes at sampling rates up to 7.2 kHz. Full array local electroretinogram currents could also be recorded at frame rates up to 100 Hz. A PIA with a full complement of 4 readout circuits would span 1cm and could acquire simultaneous data from selected regions of 1024 electrodes at sampling rates up to 9.3 kHz. Published by Elsevier B.V.

A Manually Operated, Advance Off-Stylet Insertion Tool for Minimally Invasive Cochlear Implantation Surgery

PubMed Central

Kratchman, Louis B.; Schurzig, Daniel; McRackan, Theodore R.; Balachandran, Ramya; Noble, Jack H.; Webster, Robert J.; Labadie, Robert F.

2014-01-01

The current technique for cochlear implantation (CI) surgery requires a mastoidectomy to gain access to the cochlea for electrode array insertion. It has been shown that microstereotactic frames can enable an image-guided, minimally invasive approach to CI surgery called percutaneous cochlear implantation (PCI) that uses a single drill hole for electrode array insertion, avoiding a more invasive mastoidectomy. Current clinical methods for electrode array insertion are not compatible with PCI surgery because they require a mastoidectomy to access the cochlea; thus, we have developed a manually operated electrode array insertion tool that can be deployed through a PCI drill hole. The tool can be adjusted using a preoperative CT scan for accurate execution of the advance off-stylet (AOS) insertion technique and requires less skill to operate than is currently required to implant electrode arrays. We performed three cadaver insertion experiments using the AOS technique and determined that all insertions were successful using CT and microdissection. PMID:22851233

Direct electrodeposition of porous gold nanowire arrays for biosensing applications.

PubMed

Zhang, Xinyi; Li, Dan; Bourgeois, Laure; Wang, Huanting; Webley, Paul A

2009-02-02

Nanochannel alumina templates are used as templates for fabrication of porous gold nanowire arrays by a direct electrodeposition method. After modification with glucose oxidase, a porous gold nanowire-array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose. The picture shows an SEM image of a nanowire array after removal of the alumina template by acid dissolution. We report the fabrication of porous gold nanowire arrays by means of a one-step electrodeposition method utilizing nanochannel alumina templates. The microstructure of gold nanowires depends strongly on the current density. The formation of porous gold nanowires is attributed to disperse crystallization under conditions of low nucleation rate. Interfacial electron transport through the porous gold nanowires is studied by electrochemical impedance spectroscopy. Cyclic voltammetric studies on the porous gold nanowire arrays reveal a low-potential electrocatalytic response towards hydrogen peroxide. The properties of the glucose oxidase modified porous gold nanowire array electrode are elucidated and compared with those of nonporous enzyme electrodes. The glucose oxidase modified porous gold nanowire-array electrode is shown to be an excellent electrochemical biosensor for the detection of glucose.

Channel microband electrode arrays for mechanistic electrochemistry. Two-dimensional voltammetry:  transport-limited currents.

PubMed

Alden, J A; Feldman, M A; Hill, E; Prieto, F; Oyama, M; Coles, B A; Compton, R G; Dobson, P J; Leigh, P A

1998-05-01

A channel electrode array, with electrodes ranging in size from the millimeter to the submicrometer scale, is used for the amperometric interrogation of mechanistically complex electrode processes. In this way, the transport-limited current, measured as a function of both electrode size and electrolyte flow rate (convection), is shown to provide a highly sensitive probe of mechanism and kinetics. The application of "two-dimensional voltammetry" to diverse electrode processes, including E, ECE, ECEE, EC', and DISP2 reactions, is reported.

Microelectrode array recordings of cardiac action potentials as a high throughput method to evaluate pesticide toxicity.

PubMed

Natarajan, A; Molnar, P; Sieverdes, K; Jamshidi, A; Hickman, J J

2006-04-01

The threat of environmental pollution, biological warfare agent dissemination and new diseases in recent decades has increased research into cell-based biosensors. The creation of this class of sensors could specifically aid the detection of toxic chemicals and their effects in the environment, such as pyrethroid pesticides. Pyrethroids are synthetic pesticides that have been used increasingly over the last decade to replace other pesticides like DDT. In this study we used a high-throughput method to detect pyrethroids by using multielectrode extracellular recordings from cardiac cells. The data from this cell-electrode hybrid system was compared to published results obtained with patch-clamp electrophysiology and also used as an alternative method to further understand pyrethroid effects. Our biosensor consisted of a confluent monolayer of cardiac myocytes cultured on microelectrode arrays (MEA) composed of 60 substrate-integrated electrodes. Spontaneous activity of these beating cells produced extracellular field potentials in the range of 100 microV to nearly 1200 microV with a beating frequency of 0.5-4 Hz. All of the tested pyrethroids; alpha-Cypermethrin, Tetramethrin and Tefluthrin, produced similar changes in the electrophysiological properties of the cardiac myocytes, namely reduced beating frequency and amplitude. The sensitivity of our toxin detection method was comparable to earlier patch-clamp studies, which indicates that, in specific applications, high-throughput extracellular methods can replace single-cell studies. Moreover, the similar effect of all three pyrethroids on the measured parameters suggests, that not only detection of the toxins but, their classification might also be possible with this method. Overall our results support the idea that whole cell biosensors might be viable alternatives when compared to current toxin detection methods.

Ratiometric biosensor array for multiplexed detection of microRNAs based on electrochemiluminescence coupled with cyclic voltammetry.

PubMed

Feng, Xiaobin; Gan, Ning; Zhang, Huairong; Li, Tianhua; Cao, Yuting; Hu, Futao; Jiang, Qianli

2016-01-15

A novel multiplexed ratiometric biosensor array was fabricated on a homemade screen-printed carbon electrode (SPCE) for near-simultaneous detection of microRNA (miRNA)-21 and miRNA-141 based on electrochemiluminescence (ECL) coupled with cyclic voltammetry (CV) method. In the detection system, the ECL signal tags (Ru-SiO2@PLL-Au) were fabricated using poly-l-lysine (PLL) as bridging agent and co-reactant to connect Ru-SiO2 (Ru(bpy)3(2+)-doped silica) and gold nanoparticles (Au NPs), which were respectively modified on two spatial resolved working electrodes (WE1 and WE2) of SPCE. Then the ferrocene (Fc)-labeled hairpin DNA (Fc-HDNA1 and Fc-HDNA2) as CV signal tags and ECL quenching material were immobilized on Ru-SiO2@PLL-Au. Upon miRNA-21 and miRNA-141 adding, the target miRNAs could hybridize with corresponding Fc-HDNA, which could lead to Fc away from Ru-SiO2@PLL-Au. Such conformational changes could recover the ECL of Ru-SiO2@PLL-Au and decreased the CV current of Fc, respectively. This "signal-on" of ECL and "signal-off" of CV were employed for dual-signal ratiometric readout. With the help of a multiplexed switch, two dual-signals from WE1 and WE2 were used for multiplexed detection of miRNA-21 and miRNA-141 down to 6.3 and 8.6fM, respectively. This approach was used in real sample analysis and has significant potential for miRNA biomarkers detection in a clinical laboratory setting. Copyright © 2015 Elsevier B.V. All rights reserved.

A front-end wafer-level microsystem packaging technique with micro-cap array

NASA Astrophysics Data System (ADS)

Chiang, Yuh-Min

2002-09-01

The back-end packaging process is the remaining challenge for the micromachining industry to commercialize microsystem technology (MST) devices at low cost. This dissertation presents a novel wafer level protection technique as a final step of the front-end fabrication process for MSTs. It facilitates improved manufacturing throughput and automation in package assembly, wafer level testing of devices, and enhanced device performance. The method involves the use of a wafer-sized micro-cap array, which consists of an assortment of small caps micro-molded onto a material with adjustable shapes and sizes to serve as protective structures against the hostile environments during packaging. The micro-cap array is first constructed by a micromachining process with micro-molding technique, then sealed to the device wafer at wafer level. Epoxy-based wafer-level micro cap array has been successfully fabricated and showed good compatibility with conventional back-end packaging processes. An adhesive transfer technique was demonstrated to seal the micro cap array with a MEMS device wafer. No damage or gross leak was observed while wafer dicing or later during a gross leak test. Applications of the micro cap array are demonstrated on MEMS, microactuators fabricated using CRONOS MUMPS process. Depending on the application needs, the micro-molded cap can be designed and modified to facilitate additional component functions, such as optical, electrical, mechanical, and chemical functions, which are not easily achieved in the device by traditional means. Successful fabrication of a micro cap array comprised with microlenses can provide active functions as well as passive protection. An optical tweezer array could be one possibility for applications of a micro cap with microlenses. The micro cap itself could serve as micro well for DNA or bacteria amplification as well.

Stretchable Transparent Electrode Arrays for Simultaneous Electrical and Optical Interrogation of Neural Circuits in Vivo.

PubMed

Zhang, Jing; Liu, Xiaojun; Xu, Wenjing; Luo, Wenhan; Li, Ming; Chu, Fangbing; Xu, Lu; Cao, Anyuan; Guan, Jisong; Tang, Shiming; Duan, Xiaojie

2018-05-09

Recent developments of transparent electrode arrays provide a unique capability for simultaneous optical and electrical interrogation of neural circuits in the brain. However, none of these electrode arrays possess the stretchability highly desired for interfacing with mechanically active neural systems, such as the brain under injury, the spinal cord, and the peripheral nervous system (PNS). Here, we report a stretchable transparent electrode array from carbon nanotube (CNT) web-like thin films that retains excellent electrochemical performance and broad-band optical transparency under stretching and is highly durable under cyclic stretching deformation. We show that the CNT electrodes record well-defined neuronal response signals with negligible light-induced artifacts from cortical surfaces under optogenetic stimulation. Simultaneous two-photon calcium imaging through the transparent CNT electrodes from cortical surfaces of GCaMP-expressing mice with epilepsy shows individual activated neurons in brain regions from which the concurrent electrical recording is taken, thus providing complementary cellular information in addition to the high-temporal-resolution electrical recording. Notably, the studies on rats show that the CNT electrodes remain operational during and after brain contusion that involves the rapid deformation of both the electrode array and brain tissue. This enables real-time, continuous electrophysiological monitoring of cortical activity under traumatic brain injury. These results highlight the potential application of the stretchable transparent CNT electrode arrays in combining electrical and optical modalities to study neural circuits, especially under mechanically active conditions, which could potentially provide important new insights into the local circuit dynamics of the spinal cord and PNS as well as the mechanism underlying traumatic injuries of the nervous system.

Flexible probe for measuring local conductivity variations in Li-ion electrode films

NASA Astrophysics Data System (ADS)

Hardy, Emilee; Clement, Derek; Vogel, John; Wheeler, Dean; Mazzeo, Brian

2018-04-01

Li-ion battery performance is governed by electronic and ionic properties of the battery. A key metric that characterizes Li-ion battery cell performance is the electronic conductivity of the electrodes, which are metal foils with thin coatings of electrochemically active materials. To accurately measure the spatial variation of electronic conductivity of these electrodes, a micro-four-line probe (μ4LP) was designed and used to non-destructively measure the properties of commercial-quality Li-ion battery films. This previous research established that the electronic conductivity of film electrodes is not homogeneous throughout the entirety of the deposited film area. In this work, a micro-N-line probe (μNLP) and a flexible micro-flex-line probe (μFLP) were developed to improve the non-destructive micro-scale conductivity measurements that we can take. These devices were validated by comparing test results to that of the predecessor, the micro-four-line probe (μ4LP), on various commercial-quality Li-ion battery electrodes. Results show that there is significant variation in conductivity on a millimeter and even micrometer length scale through the electrode film. Compared to the μ4LP, the μNLP and μFLP also introduce additional measurement configuration possibilities, while providing a more robust design. Researchers and manufacturers can use these probes to identify heterogeneity in their electrodes during the fabrication process, which will lead to the development of better batteries.

Recognition of the epicardial breakthrough on body surface isopotential maps: influence of the inter-electrode distance on the patterns reflecting the epicardial breakthrough.

PubMed

Toyama, J; Tabata, O

1981-10-01

The epicardial breakthrough can be recognized from the localized depression of the body surface potential, which is characterized by a localized bend of the equipotential lines or a send-minimum on isopotential maps. Recognition of epicardial breakthrough with isopotential maps enables us to diagnose location of the block site of the bundle branch blocks more precisely than by ECG or VCG. However, the optimum inter-electrode distance for detection of such a localized potential has not been determined. In the present study, influence of the inter-electrode distance on the characteristic patterns reflecting the epicardial breakthrough was studied on 16 healthy persons using 9 x 9 electrode arrays with inter-electrode distance of 1.25 cm, 5 x 5 with 2.5 cm, and 3 x 3 with 5 cm. Breakthrough was recognized in 15 out of 16 cases (94%) on maps recorded with electrode arrays with inter-electrode distance of 1.25 and 2.5 cm. However, detectability of the breakthrough was reduced to 10 out of 16 cases (63%) with electrode array having inter-electrode distance of 5 cm. In conclusion, it is preferable to use an electrode array with an inter-electrode distance of no more than 2.5 cm for the purpose of breakthrough recognition.

Clinical applications of penetrating neural interfaces and Utah Electrode Array technologies

NASA Astrophysics Data System (ADS)

Normann, Richard A.; Fernandez, Eduardo

2016-12-01

This paper briefly describes some of the recent progress in the development of penetrating microelectrode arrays and highlights the use of two of these devices, Utah electrode arrays and Utah slanted electrode arrays, in two therapeutic interventions: recording volitional skeletal motor commands from the central nervous system, and recording motor commands and evoking somatosensory percepts in the peripheral nervous system (PNS). The paper also briefly explores other potential sites for microelectrode array interventions that could be profitably pursued and that could have important consequences in enhancing the quality of life of patients that has been compromised by disorders of the central and PNSs.

Disposable sensor based on enzyme-free Ni nanowire array electrode to detect glutamate.

PubMed

Jamal, Mamun; Hasan, Maksudul; Mathewson, Alan; Razeeb, Kafil M

2013-02-15

Enzyme free electrochemical sensor platform based on a vertically aligned nickel nanowire array (NiNAE) and Pt coated nickel nanowire array (Pt/NiNAE) have been developed to detect glutamate. Morphological characterisation of Ni electrodes was carried out using scanning and transmission electron microscopy combined with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the NiNAE and the Pt/NiNAE for glutamate. It has been found that both NiNAE and Pt/NiNAE electrodes showed remarkably enhanced electrocatalytic activity towards glutamate compared to planar Ni electrodes, and showed higher catalytic activity when compared to other metallic nanostructure electrodes such as gold nanowire array electrodes (AuNAE) and Pt coated gold nanowire array electrode (Pt/AuNAE). The sensitivity of NiNAE and Pt/NiNAE has been found to be 65 and 96 μA mM(-1) cm(-2), respectively, which is approximately 6 to 9 times higher than the state of the art glutamate sensor. Under optimal detection conditions, the as prepared sensors exhibited linear behaviour for glutamate detection in the concentration up to 8mM for both NiNAE and Pt/NiNAE with a limit of detection of 68 and 83 μM, respectively. Experimental results show that the vertically aligned ordered nickel nanowire array electrode (NiNAE) has significant promise for fabricating cost effective, enzyme-less, sensitive, stable and selective sensor platform. Copyright © 2012 Elsevier B.V. All rights reserved.

Fabrication of a 3D micro/nano dual-scale carbon array and its demonstration as the microelectrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Jiang, Shulan; Shi, Tielin; Gao, Yang; Long, Hu; Xi, Shuang; Tang, Zirong

2014-04-01

An easily accessible method is proposed for the fabrication of a 3D micro/nano dual-scale carbon array with a large surface area. The process mainly consists of three critical steps. Firstly, a hemispherical photoresist micro-array was obtained by the cost-effective nanoimprint lithography process. Then the micro-array was transformed into hierarchical structures with longitudinal nanowires on the microstructure surface by oxygen plasma etching. Finally, the micro/nano dual-scale carbon array was fabricated by carbonizing these hierarchical photoresist structures. It has also been demonstrated that the micro/nano dual-scale carbon array can be used as the microelectrodes for supercapacitors by the electrodeposition of a manganese dioxide (MnO2) film onto the hierarchical carbon structures with greatly enhanced electrochemical performance. The specific gravimetric capacitance of the deposited micro/nano dual-scale microelectrodes is estimated to be 337 F g-1 at the scan rate of 5 mV s-1. This proposed approach of fabricating a micro/nano dual-scale carbon array provides a facile way in large-scale microstructures’ manufacturing for a wide variety of applications, including sensors and on-chip energy storage devices.

An integrated micro-manipulation and biosensing platform built in glass-based LTPS TFT technology

NASA Astrophysics Data System (ADS)

Chen, Lei-Guang; Wu, Dong-Yi; S-C Lu, Michael

2012-09-01

The glass-based low-temperature polycrystalline-silicon (LTPS) thin-film transistor (TFT) process, widely known for making liquid crystal displays, is utilized in this work to realize a fully integrated, microbead-based micro-manipulation and biosensing platform. The operation utilizes arrays of microelectrodes made of transparent iridium tin oxide (ITO) to move the immobilized polystyrene microbeads to the sensor surface by dielectrophoresis (DEP). Detection of remaining microbeads after a specific antigen/antibody reaction is accomplished by photo-detectors under the transparent electrodes. It was found that microbeads can be driven successfully by the 30 × 30 µm2 microelectrodes separated by 10 µm with no more than 6 Vp-p, which is compatible with the operating range of thin-film transistors. Microbeads immobilized with antimouse immunoglobulin (IgG) and prostate-specific antigen (PSA) antibody were successfully detected after specific binding, illustrating the potential of LTPS TFT microarrays for more versatile biosensing applications.

Focused shock spark discharge drill using multiple electrodes

DOEpatents

Moeny, William M.; Small, James G.

1988-01-01

A spark discharge focused drill provided with one pulse forming line or a number of pulse forming lines. The pulse forming line is connected to an array of electrodes which would form a spark array. One of the electrodes of each of the array is connected to the high voltage side of the pulse forming line and the other electrodes are at ground potential. When discharged in a liquid, these electrodes produce intense focused shock waves that can pulverize or fracture rock. By delaying the firing of each group of electrodes, the drill can be steered within the earth. Power can be fed to the pulse forming line either downhole or from the surface area. A high voltage source, such as a Marx generator, is suitable for pulse charging the lines.

Robust Functionalization of Large Microelectrode Arrays by Using Pulsed Potentiostatic Deposition

PubMed Central

Rothe, Joerg; Frey, Olivier; Madangopal, Rajtarun; Rickus, Jenna; Hierlemann, Andreas

2016-01-01

Surface modification of microelectrodes is a central step in the development of microsensors and microsensor arrays. Here, we present an electrodeposition scheme based on voltage pulses. Key features of this method are uniformity in the deposited electrode coatings, flexibility in the overall deposition area, i.e., the sizes and number of the electrodes to be coated, and precise control of the surface texture. Deposition and characterization of four different materials are demonstrated, including layers of high-surface-area platinum, gold, conducting polymer poly(ethylenedioxythiophene), also known as PEDOT, and the non-conducting polymer poly(phenylenediamine), also known as PPD. The depositions were conducted using a fully integrated complementary metal-oxide-semiconductor (CMOS) chip with an array of 1024 microelectrodes. The pulsed potentiostatic deposition scheme is particularly suitable for functionalization of individual electrodes or electrode subsets of large integrated microelectrode arrays: the required deposition waveforms are readily available in an integrated system, the same deposition parameters can be used to functionalize the surface of either single electrodes or large arrays of thousands of electrodes, and the deposition method proved to be robust and reproducible for all materials tested. PMID:28025569

High-channel-count, high-density microelectrode array for closed-loop investigation of neuronal networks.

PubMed

Tsai, David; John, Esha; Chari, Tarun; Yuste, Rafael; Shepard, Kenneth

2015-01-01

We present a system for large-scale electrophysiological recording and stimulation of neural tissue with a planar topology. The recording system has 65,536 electrodes arranged in a 256 × 256 grid, with 25.5 μm pitch, and covering an area approximately 42.6 mm(2). The recording chain has 8.66 μV rms input-referred noise over a 100 ~ 10k Hz bandwidth while providing up to 66 dB of voltage gain. When recording from all electrodes in the array, it is capable of 10-kHz sampling per electrode. All electrodes can also perform patterned electrical microstimulation. The system produces ~ 1 GB/s of data when recording from the full array. To handle, store, and perform nearly real-time analyses of this large data stream, we developed a framework based around Xilinx FPGAs, Intel x86 CPUs and the NVIDIA Streaming Multiprocessors to interface with the electrode array.

Hierarchical nano-on-micro copper with enhanced catalytic activity towards electro-oxidation of hydrazine

NASA Astrophysics Data System (ADS)

Yan, Xiaodong; Liu, Yuan; Scheel, Kyle R.; Li, Yong; Yu, Yunhua; Yang, Xiaoping; Peng, Zhonghua

2018-03-01

The electrochemical properties of catalyst materials are highly dependent on the materials structure and architecture. Herein, nano-on-micro Cu electrodes are fabricated by growing Cu microcrystals on Ni foam substrate, followed by introducing Cu nanocrystals onto the surface of the Cu microcrystals. The introduction of Cu nanocrystals onto the surface of Cu microcrystals is shown to dramatically increase the electrochemically active surface area and thus significantly enhances the catalytic activity of the catalyst electrode towards electro-oxidation of hydrazine. The onset potential (-1.04 V vs. Ag/AgCl) of the nano-on-micro Cu electrode is lower than those of the reported Cu-based catalysts under similar testing conditions, and a current density of 16 mA·cm-2, which is 2 times that of the microsized Cu electrode, is achieved at a potential of -0.95 V vs. Ag/AgCl. Moreover, the nano-on-micro Cu electrode demonstrates good long-term stability.

CRSP, numerical results for an electrical resistivity array to detect underground cavities

NASA Astrophysics Data System (ADS)

Amini, Amin; Ramazi, Hamidreza

2017-03-01

This paper is devoted to the application of the Combined Resistivity Sounding and Profiling electrode configuration (CRSP) to detect underground cavities. Electrical resistivity surveying is among the most favorite geophysical methods due to its nondestructive and economical properties in a wide range of geosciences. Several types of the electrode arrays are applied to detect different certain objectives. In one hand, the electrode array plays an important role in determination of output resolution and depth of investigations in all resistivity surveys. On the other hand, they have their own merits and demerits in terms of depth of investigations, signal strength, and sensitivity to resistivity variations. In this article several synthetic models, simulating different conditions of cavity occurrence, were used to examine the responses of some conventional electrode arrays and also CRSP array. The results showed that CRSP electrode configuration can detect the desired objectives with a higher resolution rather than some other types of arrays. Also a field case study was discussed in which electrical resistivity approach was conducted in Abshenasan expressway (Tehran, Iran) U-turn bridge site for detecting potential cavities and/or filling loose materials. The results led to detect an aqueduct tunnel passing beneath the study area.

Non-invasive method for selection of electrodes and stimulus parameters for FES applications with intrafascicular arrays

NASA Astrophysics Data System (ADS)

Dowden, B. R.; Frankel, M. A.; Normann, R. A.; Clark, G. A.

2012-02-01

High-channel-count intrafascicular electrode arrays provide comprehensive and selective access to the peripheral nervous system. One practical difficulty in using several electrode arrays to evoke coordinated movements in paralyzed limbs is the identification of the appropriate stimulation channels and stimulus parameters to evoke desired movements. Here we present the use of a six degree-of-freedom load cell placed under the foot of a feline to characterize the muscle activation produced by three 100-electrode Utah Slanted Electrode Arrays (USEAs) implanted into the femoral nerves, sciatic nerves, and muscular branches of the sciatic nerves of three cats. Intramuscular stimulation was used to identify the endpoint force directions produced by 15 muscles of the hind limb, and these directions were used to classify the forces produced by each intrafascicular USEA electrode as flexion or extension. For 451 USEA electrodes, stimulus intensities for threshold and saturation muscle forces were identified, and the 3D direction and linearity of the force recruitment curves were determined. Further, motor unit excitation independence for 198 electrode pairs was measured using the refractory technique. This study demonstrates the utility of 3D endpoint force monitoring as a simple and non-invasive metric for characterizing the muscle-activation properties of hundreds of implanted peripheral nerve electrodes, allowing for electrode and parameter selection for neuroprosthetic applications.

Non-invasive method for selection of electrodes and stimulus parameters for FES applications with intrafascicular arrays.

PubMed

Dowden, B R; Frankel, M A; Normann, R A; Clark, G A

2012-02-01

High-channel-count intrafascicular electrode arrays provide comprehensive and selective access to the peripheral nervous system. One practical difficulty in using several electrode arrays to evoke coordinated movements in paralyzed limbs is the identification of the appropriate stimulation channels and stimulus parameters to evoke desired movements. Here we present the use of a six degree-of-freedom load cell placed under the foot of a feline to characterize the muscle activation produced by three 100-electrode Utah Slanted Electrode Arrays (USEAs) implanted into the femoral nerves, sciatic nerves, and muscular branches of the sciatic nerves of three cats. Intramuscular stimulation was used to identify the endpoint force directions produced by 15 muscles of the hind limb, and these directions were used to classify the forces produced by each intrafascicular USEA electrode as flexion or extension. For 451 USEA electrodes, stimulus intensities for threshold and saturation muscle forces were identified, and the 3D direction and linearity of the force recruitment curves were determined. Further, motor unit excitation independence for 198 electrode pairs was measured using the refractory technique. This study demonstrates the utility of 3D endpoint force monitoring as a simple and non-invasive metric for characterizing the muscle-activation properties of hundreds of implanted peripheral nerve electrodes, allowing for electrode and parameter selection for neuroprosthetic applications.

A small-gap electrostatic micro-actuator for large deflections

PubMed Central

Conrad, Holger; Schenk, Harald; Kaiser, Bert; Langa, Sergiu; Gaudet, Matthieu; Schimmanz, Klaus; Stolz, Michael; Lenz, Miriam

2015-01-01

Common quasi-static electrostatic micro actuators have significant limitations in deflection due to electrode separation and unstable drive regions. State-of-the-art electrostatic actuators achieve maximum deflections of approximately one third of the electrode separation. Large electrode separation and high driving voltages are normally required to achieve large actuator movements. Here we report on an electrostatic actuator class, fabricated in a CMOS-compatible process, which allows high deflections with small electrode separation. The concept presented makes the huge electrostatic forces within nanometre small electrode separation accessible for large deflections. Electrostatic actuations that are larger than the electrode separation were measured. An analytical theory is compared with measurement and simulation results and enables closer understanding of these actuators. The scaling behaviour discussed indicates significant future improvement on actuator deflection. The presented driving concept enables the investigation and development of novel micro systems with a high potential for improved device and system performance. PMID:26655557

Quantum Information Experiments with Trapped Ions at NIST

NASA Astrophysics Data System (ADS)

Wilson, Andrew

2015-03-01

We present an overview of recent trapped-ion quantum information experiments at NIST. Advancing beyond few-qubit ``proof-of-principle'' experiments to the many-qubit systems needed for practical quantum simulation and information processing, without compromising on the performance demonstrated with small systems, remains a major challenge. One approach to scalable hardware development is surface-electrode traps. Micro-fabricated planar traps can have a number of useful features, including flexible electrode geometries, integrated microwave delivery, and spatio-temporal tuning of potentials for ion transport and spin-spin interactions. In this talk we report on a number of on-going investigations with surface traps. Experiments feature a multi-zone trap with closely spaced ions in a triangular arrangement (a first step towards 2D arrays of ions with tunable spin-spin interactions), a scheme for smooth transport through a junction in a 2D structure based on switchable RF potentials, and a micro-fabricated photo-detector integrated into a trap. We also give a progress report on our latest efforts to improve the fidelity of both optical and microwave 2-qubit gates. This work was supported by IARPA, ONR and the NIST Quantum Information Program. The 3-ion and switchable-RF-junction traps were developed in collaboration with Sandia National Laboratory.

A machine vision system for micro-EDM based on linux

NASA Astrophysics Data System (ADS)

Guo, Rui; Zhao, Wansheng; Li, Gang; Li, Zhiyong; Zhang, Yong

2006-11-01

Due to the high precision and good surface quality that it can give, Electrical Discharge Machining (EDM) is potentially an important process for the fabrication of micro-tools and micro-components. However, a number of issues remain unsolved before micro-EDM becomes a reliable process with repeatable results. To deal with the difficulties in micro electrodes on-line fabrication and tool wear compensation, a micro-EDM machine vision system is developed with a Charge Coupled Device (CCD) camera, with an optical resolution of 1.61μm and an overall magnification of 113~729. Based on the Linux operating system, an image capturing program is developed with the V4L2 API, and an image processing program is exploited by using OpenCV. The contour of micro electrodes can be extracted by means of the Canny edge detector. Through the system calibration, the micro electrodes diameter can be measured on-line. Experiments have been carried out to prove its performance, and the reasons of measurement error are also analyzed.

Microfabricated instruments and methods to treat recurrent corneal erosions

DOEpatents

Britton, Jr., Charles L.; D'urso, Brian R.; Chaum, Edward; Simpson, John T.; Baba, Justin S.; Ericson, M. Nance; Warmack, Robert J.

2015-06-02

In one embodiment, the present invention provides a device and method for treating recurrent corneal erosion. In one embodiment, the method includes the steps of contacting an epithelium layer of a cornea with an array of glass micro-rods including a plurality of sharp features having a length that penetrates a Bowman's layer of the eye, wherein the plurality of sharp features of the array of glass micro-rods produces a plurality of punctures in the Bowman's layer of the eye that are of micro-scale or less. In another embodiment, the present invention provides a method and device for drug delivery. In one embodiment, the device includes an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods, wherein the sharp feature includes a treated surface for delivering a chemical compound to the eye.

Microfabricated instruments and methods to treat recurrent corneal erosion

DOEpatents

Britton, Charles L; D& #x27; Urso, Brian R; Chaum, Edward; Simpson, John T; Baba, Justin S; Ericson, M. Nance; Warmack, Robert J

2013-11-26

In one embodiment, the present invention provides a device and method for treating recurrent corneal erosion. In one embodiment, the method includes the steps of contacting an epithelium layer of a cornea with an array of glass micro-rods including a plurality of sharp features having a length that penetrates a Bowman's layer of the eye, wherein the plurality of sharp features of the array of glass micro-rods produces a plurality of punctures in the Bowman's layer of the eye that are of micro-scale or less. In another embodiment, the present invention provides a method and device for drug delivery. In one embodiment, the device includes an array of glass micro-rods, wherein at least one glass micro-rod of the array of glass micro-rods includes a sharp feature opposite a base of the array of glass micro-rods, wherein the sharp feature includes a treated surface for delivering a chemical compound to the eye.

Microelectrode array-induced neuronal alignment directs neurite outgrowth: analysis using a fast Fourier transform (FFT).

PubMed

Radotić, Viktorija; Braeken, Dries; Kovačić, Damir

2017-12-01

Many studies have shown that the topography of the substrate on which neurons are cultured can promote neuronal adhesion and guide neurite outgrowth in the same direction as the underlying topography. To investigate this effect, isotropic substrate-complementary metal-oxide-semiconductor (CMOS) chips were used as one example of microelectrode arrays (MEAs) for directing neurite growth of spiral ganglion neurons. Neurons were isolated from 5 to 7-day-old rat pups, cultured 1 day in vitro (DIV) and 4 DIV, and then fixed with 4% paraformaldehyde. For analysis of neurite alignment and orientation, fast Fourier transformation (FFT) was used. Results revealed that on the micro-patterned surface of a CMOS chip, neurons orient their neurites along three directional axes at 30, 90, and 150° and that neurites aligned in straight lines between adjacent pillars and mostly followed a single direction while occasionally branching perpendicularly. We conclude that the CMOS substrate guides neurites towards electrodes by means of their structured pillar organization and can produce electrical stimulation of aligned neurons as well as monitoring their neural activities once neurites are in the vicinity of electrodes. These findings are of particular interest for neural tissue engineering with the ultimate goal of developing a new generation of MEA essential for improved electrical stimulation of auditory neurons.

Initial Operative Experience and Short-term Hearing Preservation Results With a Mid-scala Cochlear Implant Electrode Array.

PubMed

Svrakic, Maja; Roland, J Thomas; McMenomey, Sean O; Svirsky, Mario A

2016-12-01

To describe our initial operative experience and hearing preservation results with the Advanced Bionics (AB) Mid Scala Electrode (MSE). Retrospective review. Tertiary referral center. Sixty-three MSE implants in pediatric and adult patients were compared with age- and sex-matched 1j electrode implants from the same manufacturer. All patients were severe to profoundly deaf. Cochlear implantation with either the AB 1j electrode or the AB MSE. The MSE and 1j electrodes were compared in their angular depth of insertion and pre to postoperative change in hearing thresholds. Hearing preservation was analyzed as a function of angular depth of insertion. Secondary outcome measures included operative time, incidence of abnormal intraoperative impedance and telemetry values, and incidence of postsurgical complications. Depth of insertion was similar for both electrodes, but was more consistent for the MSE array and more variable for the 1j array. Patients with MSE electrodes had better hearing preservation. Thresholds shifts at four audiometric frequencies ranging from 250 to 2000 Hz were 10, 7, 2, and 6 dB smaller for the MSE electrode than for the 1j (p < 0.05). Hearing preservation at low frequencies was worse with deeper insertion, regardless of array. Secondary outcome measures were similar for both electrodes. The MSE electrode resulted in more consistent insertion depth and somewhat better hearing preservation than the 1j electrode. Differences in other surgical outcome measures were small or unlikely to have a meaningful effect.

Comparison of the HiFocus Mid-Scala and HiFocus 1J Electrode Array: Angular Insertion Depths and Speech Perception Outcomes.

PubMed

van der Jagt, M Annerie; Briaire, Jeroen J; Verbist, Berit M; Frijns, Johan H M

2016-01-01

The HiFocus Mid-Scala (MS) electrode array has recently been introduced onto the market. This precurved design with a targeted mid-scalar intracochlear position pursues an atraumatic insertion and optimal distance for neural stimulation. In this study we prospectively examined the angular insertion depth achieved and speech perception outcomes resulting from the HiFocus MS electrode array for 6 months after implantation, and retrospectively compared these with the HiFocus 1J lateral wall electrode array. The mean angular insertion depth within the MS population (n = 96) was found at 470°. This was 50° shallower but more consistent than the 1J electrode array (n = 110). Audiological evaluation within a subgroup, including only postlingual, unilaterally implanted, adult cochlear implant recipients who were matched on preoperative speech perception scores and the duration of deafness (MS = 32, 1J = 32), showed no difference in speech perception outcomes between the MS and 1J groups. Furthermore, speech perception outcome was not affected by the angular insertion depth or frequency mismatch. © 2016 S. Karger AG, Basel.

A New Semi-Automatic Approach to Find Suitable Virtual Electrodes in Arrays Using an Interpolation Strategy.

PubMed

Salchow, Christina; Valtin, Markus; Seel, Thomas; Schauer, Thomas

2016-06-13

Functional Electrical Stimulation via electrode arrays enables the user to form virtual electrodes (VEs) of dynamic shape, size, and position. We developed a feedback-control-assisted manual search strategy which allows the therapist to conveniently and continuously modify VEs to find a good stimulation area. This works for applications in which the desired movement consists of at least two degrees of freedom. The virtual electrode can be moved to arbitrary locations within the array, and each involved element is stimulated with an individual intensity. Meanwhile, the applied global stimulation intensity is controlled automatically to meet a predefined angle for one degree of freedom. This enables the therapist to concentrate on the remaining degree(s) of freedom while changing the VE position. This feedback-control-assisted approach aims to integrate the user's opinion and the patient's sensation. Therefore, our method bridges the gap between manual search and fully automatic identification procedures for array electrodes. Measurements in four healthy volunteers were performed to demonstrate the usefulness of our concept, using a 24-element array to generate wrist and hand extension.

Elastic Distribution of Microshutters, Measurements Obtainable on James Web Space Telescope

NASA Technical Reports Server (NTRS)

Kletetschka, Gunther; King, Todd; Mikula, Vilem

2008-01-01

Spectrographic astronomy measurements in the near-infrared region will be done by functional two-dimensional microshutter arrays that are being fabricated at the NASA Goddard Space Flight Center for the James Webb Space Telescope (JWST). These micro-shutter arrays will represent the first mission-critical MEMS devices to be flown in space. JWST will use microshutter arrays to select focal plane object. 2-D programmable aperture masks of more than 200,000 elements select such space object. The use of silicon wafer material promises high efficiency and high contrast. Microshutter operation temperature is around 35K. Microshutter arrays are fabricated as close-packed silicon nitride membranes with a unit cell size of 105 x 204 micrometers. A layer of magnetic material is deposited onto each shutter. Individual shutters are equipped with a torsion flexure. Reactive ion etching (RIE) releases the shutters so they can open up to 90 degrees using the torsion flexure. Shutter rotation is initiated into a silicon support structure via an external magnetic field. Two electrically independent aluminum electrodes are deposited, one onto each shutter and another onto the support structure side-wall, permitting electrostatic latching and 2-D addressing to hold specific shutters open via external electronics.

Nano-porous electrode systems by colloidal lithography for sensitive electrochemical detection: fabrication technology and properties

NASA Astrophysics Data System (ADS)

Lohmüller, Theobald; Müller, Ulrich; Breisch, Stefanie; Nisch, Wilfried; Rudorf, Ralf; Schuhmann, Wolfgang; Neugebauer, Sebastian; Kaczor, Markus; Linke, Stephan; Lechner, Sebastian; Spatz, Joachim; Stelzle, Martin

2008-11-01

A porous metal-insulator-metal sensor system was developed with the ultimate goal of enhancing the sensitivity of electrochemical sensors by taking advantage of redox cycling of electro active molecules between closely spaced electrodes. The novel fabrication technology is based on thin film deposition in combination with colloidal self-assembly and reactive ion etching to create micro- or nanopores. This cost effective approach is advantageous compared to common interdigitated electrode arrays (IDA) since it does not require high definition lithography technology. Spin-coating and random particle deposition, combined with a new sublimation process are discussed as competing strategies to generate monolayers of colloidal spheres. Metal-insulator-metal layer systems with low leakage currents < 10 pA and an insulator thickness as low as 100 nm were obtained at high yield (typically > 90%). We also discuss possible causes of sensor failure with respect to critical fabrication processes. Short circuits which could occur during or as a result of the pore etching process were investigated in detail. Infrared microscopy in combination with focused ion beam etching/SEM were used to reveal a defect mechanism creating interconnects and increased leakage current between the top and bottom electrodes. Redox cycling provides for amplification factors of >100. A general applicability for electrochemical diagnostic assays is therefore anticipated.

Development of a multiplexed electrospray micro-thruster with post-acceleration and beam containment

NASA Astrophysics Data System (ADS)

Lenguito, G.; Gomez, A.

2013-10-01

We report the development of a compact thruster based on Multiplexed ElectroSprays (MES). It relied on a microfabricated Si array of emitters coupled with an extractor electrode and an accelerator electrode. The accelerator stage was introduced for two purposes: containing beam opening and avoiding electrode erosion due to droplet impingement, as well as boosting specific impulse and thrust. Multiplexing is generally necessary as a thrust multiplier to reach eventually the level required (O(102) μN) by small satellites. To facilitate system optimization and debugging, we focused on a 7-nozzle MES device and compared its performance to that of a single emitter. To ensure uniformity of operation of all nozzles their hydraulic impedance was augmented by packing them with micrometer-size beads. Two propellants were tested: a solution of 21.5% methyl ammonium formate in formamide and the better performing pure ionic liquid ethyl ammonium nitrate (EAN). The 7-MES device spraying EAN at ΔV = 5.93 kV covered a specific impulse range from 620 s to 1900 s and a thrust range from 0.6 μN to 5.4 μN, at 62% efficiency. Remarkably, less than 1% of the beam was demonstrated to impact on the accelerator electrode, which bodes well for long-term applications in space.

Braided multi-electrode probes: mechanical compliance characteristics and recordings from spinal cords

PubMed Central

Kim, Taegyo; Branner, Almut; Gulati, Tanuj

2013-01-01

Objective To test a novel braided multi-electrode probe design with compliance exceeding that of a 50-micron microwire, thus reducing micromotion and macromotion induced tissue stress. Approach We use up to 24 ultra-fine wires interwoven into a tubular braid to obtain a highly flexible multi-electrode probe. The tether-portion wires are simply non-braided extensions of the braid structure, allowing the microprobe to follow gross neural tissue movements. Mechanical calculation and direct measurements evaluated bending stiffness and axial compression forces in the probe and tether system. These were compared to 50μm Nichrome microwire standards. Recording tests were performed in decerebrate animals. Main results Mechanical bending tests on braids comprising 9.6μm or 12.7μm Nichrome wires showed that implants (braided portions) had 4 to 21 times better mechanical compliance than a single 50μm wire and non-braided tethers were 6 to 96 times better. Braided microprobes yielded robust neural recordings from animals’ spinal cords throughout cord motions. Significance Microwire electrode arrays that can record and withstand tissue micro- and macromotion of spinal cord tissues are demonstrated. This technology may provide a stable chronic neural interface into spinal cords of freely moving animals, is extensible to various applications, and may reduce mechanical tissue stress. PMID:23723128

Braided multi-electrode probes: mechanical compliance characteristics and recordings from spinal cords

NASA Astrophysics Data System (ADS)

Kim, Taegyo; Branner, Almut; Gulati, Tanuj; Giszter, Simon F.

2013-08-01

Objective. To test a novel braided multi-electrode probe design with compliance exceeding that of a 50 µm microwire, thus reducing micromotion- and macromotion-induced tissue stress. Approach. We use up to 24 ultra-fine wires interwoven into a tubular braid to obtain a highly flexible multi-electrode probe. The tether-portion wires are simply non-braided extensions of the braid structure, allowing the microprobe to follow gross neural tissue movements. Mechanical calculation and direct measurements evaluated bending stiffness and axial compression forces in the probe and tether system. These were compared to 50 µm nichrome microwire standards. Recording tests were performed in decerebrate animals. Main results. Mechanical bending tests on braids comprising 9.6 or 12.7 µm nichrome wires showed that implants (braided portions) had 4 to 21 times better mechanical compliance than a single 50 µm wire and non-braided tethers were 6 to 96 times better. Braided microprobes yielded robust neural recordings from animals' spinal cords throughout cord motions. Significance. Microwire electrode arrays that can record and withstand tissue micro- and macromotion of spinal cord tissues are demonstrated. This technology may provide a stable chronic neural interface into spinal cords of freely moving animals, is extensible to various applications, and may reduce mechanical tissue stress.

Fabrication of self-expandable NiTi thin film devices with micro-electrode array for bioelectric sensing, stimulation and ablation.

PubMed

Bechtold, Christoph; de Miranda, Rodrigo Lima; Chluba, Christoph; Quandt, Eckhard

2016-12-01

Self-expandable medical devices provide mechanical functionality at a specific location of the human body and are viable for minimal invasive procedures. Besides radiopaque markers and drug-eluting coatings, next generation self-expandable devices can be equipped with additional functionality, such as conductive and flexible electrodes, which enables chronic recording of bioelectrical signals, stimulating or ablating tissue. This promises new therapeutic options in various medical fields, among them in particular neuromodulation (e.g. deep brain stimulation), BioMEMS, radio frequency ablation, mapping or denervation. However, the fabrication of such multi-functional devices is challenging. For this study we have realized a 35 μm thick, superelastic NiTi thin film stent structure with six isolated electrodes on the outer circumference, each electrode connected to a contact pad at the end of the stent structure, using magnetron sputtering, UV lithography and wet chemical etching. Mechanical and electrical properties of the device during typical loading conditions, i.e. crimping, simulated pulsatile and electrochemical testing, were characterized and reveal promising results. For the fabrication of future multifunctional, minimal invasive medical devices, such as electroceuticals or other intelligent implants, NiTi thin film technology is therefore a versatile alternative to conventional fabrication routes.

Simulating pad-electrodes with high-definition arrays in transcranial electric stimulation

NASA Astrophysics Data System (ADS)

Kempe, René; Huang, Yu; Parra, Lucas C.

2014-04-01

Objective. Research studies on transcranial electric stimulation, including direct current, often use a computational model to provide guidance on the placing of sponge-electrode pads. However, the expertise and computational resources needed for finite element modeling (FEM) make modeling impractical in a clinical setting. Our objective is to make the exploration of different electrode configurations accessible to practitioners. We provide an efficient tool to estimate current distributions for arbitrary pad configurations while obviating the need for complex simulation software. Approach. To efficiently estimate current distributions for arbitrary pad configurations we propose to simulate pads with an array of high-definition (HD) electrodes and use an efficient linear superposition to then quickly evaluate different electrode configurations. Main results. Numerical results on ten different pad configurations on a normal individual show that electric field intensity simulated with the sampled array deviates from the solutions with pads by only 5% and the locations of peak magnitude fields have a 94% overlap when using a dense array of 336 electrodes. Significance. Computationally intensive FEM modeling of the HD array needs to be performed only once, perhaps on a set of standard heads that can be made available to multiple users. The present results confirm that by using these models one can now quickly and accurately explore and select pad-electrode montages to match a particular clinical need.

Laminated chemical and physical micro-jet actuators based on conductive media

NASA Astrophysics Data System (ADS)

Gadiraju, Priya D.

2008-04-01

This dissertation presents the development of electrically-powered, lamination-based microactuators for the realization of large arrays of high impulse and short duration micro-jets with potential applications in the field of micro-electro-mechanical systems (MEMS). Microactuators offer unique control opportunities by converting the input electrical or chemical energy stored in a propellant into useful mechanical energy. This small and precise control obtained can potentially be applied towards aerodynamic control and transdermal drug delivery applications. This thesis work discusses the feasibility of using microactuators for two such applications: Control of the motion of a spinning projectile by utilizing the chemically-driven microjets ejected from the actuators, and enhancement of the permeability properties of skin by selectively ablating the stratum corneum layer of skin using the physical microjets ejected from the actuators. This enhanced permeability of skin can later be used for the delivery of high molecular weight drugs for transdermal drug delivery. The development of electrically powered microactuators starts by fabricating an array of radially firing microactuators using lamination-based microfabrication techniques that potentially enable batch fabrication at low cost. The microactuators of this thesis consist of three main parts: a micro chamber in which the propellant is stored; two electrode structures through which electrical energy is supplied to the propellant; and a micro nozzle through which the propellant or released gases from the propellant are expanded as a jet. Once the actuators are fabricated, they are integrated with MEMS-process-compatible propellants and optimized so as to produce instantaneous ignition of the propellant. This instantaneous ignition is achieved either by making the propellant itself conductive, thus, passing an electric current directly through the propellant; or by discharging an arc across the propellant by placing it between two closely spaced electrodes. The first concept is demonstrated for the application of projectile maneuvering where energetic solid propellant is used in generating a high velocity gaseous jet and the second concept is demonstrated for transdermal drug delivery application where a rapid physical jet of a non-energetic propellant is generated. In the case of chemical-based microactuators, the feasibility of using conductive solid propellant based actuators for maneuvering a 25 mm bluff body projectile spinning at 600 Hz is presented. Several conductive solid propellants are developed and characterized for their electrical conductivity and required ignition energy. Finally, the propellant integrated microactuators are characterized for performance in terms of impulse delivered, thrust generated and duration of the jet. These experimental results are then compared to predicted results from simulations. In the case of physical based microactuators, the feasibility of using released physical jets from the microactuator array for transdermal drug delivery application is presented. Several bio-compatible and FDA-approved liquids are used as propellants and are characterized in terms of thrusts delivered and duration of the released jets. These thermo-mechanical jets are then used to expose skin locally so as to create micro conduits in the stratum corneum layer of skin. Both thermal effects and thermo-mechanical effects of the jet on exposed skin are studied. For both cases, histology of exposed skin is presented and its permeability to drug analog molecules is studied.

Electrochemical incineration of wastes

NASA Technical Reports Server (NTRS)

Bockris, J. O. M.; Bhardwaj, R. C.; Tennakoon, C. L. K.

1993-01-01

There is an increasing concern regarding the disposal of human wastes in space vehicles. It is of utmost importance to convert such wastes into harmless products which can be recycled into an Environmental Life Support System (CELSS), which incorporates the growth of plants (e.g. wheat) and algae to supplement the diet of the astronauts. Chemical treatments have proven relatively unsatisfactory and tend to be increasingly so with increase of the mission duration. Similarly, the use of heat to destroy wastes and convert them to CO2 by the use of air or oxygen has the disadvantage and difficulty of dissipating heat in a space environment and to the inevitable presence of oxides of nitrogen and carbon monoxide in the effluent gases. In particular, electrochemical techniques offer several advantages including low temperatures which may be used and the absence of any NO and CO in the evolved gases. Successful research has been carried out in the electrochemical oxidation of wastes over the last several years. The major task for 1992 was to conduct parametric studies in preparation for the building of a breadboard system, i.e., an actual practical device to consume the daily waste output of one astronaut in 24 hours, electrochemical incineration of human wastes in space vehicles. One of the main objectives was to decide on the type of three dimensional or other electrode system that would suit this purpose. The various types of electrode systems which were considered for this purpose included: rotating disc electrode, micro-electrode (an array), vibrating electrode, jet electrode, and packed bed electrode.

High Packing Density Unidirectional Arrays of Vertically Aligned Graphene with Enhanced Areal Capacitance for High-Power Micro-Supercapacitors.

PubMed

Zheng, Shuanghao; Li, Zhilin; Wu, Zhong-Shuai; Dong, Yanfeng; Zhou, Feng; Wang, Sen; Fu, Qiang; Sun, Chenglin; Guo, Liwei; Bao, Xinhe

2017-04-25

Interfacial integration of a shape-engineered electrode with a strongly bonded current collector is the key for minimizing both ionic and electronic resistance and then developing high-power supercapacitors. Herein, we demonstrated the construction of high-power micro-supercapacitors (VG-MSCs) based on high-density unidirectional arrays of vertically aligned graphene (VG) nanosheets, derived from a thermally decomposed SiC substrate. The as-grown VG arrays showed a standing basal plane orientation grown on a (0001̅) SiC substrate, tailored thickness (3.5-28 μm), high-density structurally ordering alignment of graphene consisting of 1-5 layers, vertically oriented edges, open intersheet channels, high electrical conductivity (192 S cm -1 ), and strong bonding of the VG edges to the SiC substrate. As a result, the demonstrated VG-MSCs displayed a high areal capacitance of ∼7.3 mF cm -2 and a fast frequency response with a short time constant of 9 ms. Furthermore, VG-MSCs in both an aqueous polymer gel electrolyte and nonaqueous ionic liquid of 1-ethyl-3-methylimidazolium tetrafluoroborate operated well at high scan rates of up to 200 V s -1 . More importantly, VG-MSCs offered a high power density of ∼15 W cm -3 in gel electrolyte and ∼61 W cm -3 in ionic liquid. Therefore, this strategy of producing high-density unidirectional VG nanosheets directly bonded on a SiC current collector demonstrated the feasibility of manufacturing high-power compact supercapacitors.

Focused intracochlear electric stimulation with phased array channels.

PubMed

van den Honert, Chris; Kelsall, David C

2007-06-01

A method is described for producing focused intracochlear electric stimulation using an array of N electrodes. For each electrode site, N weights are computed that define the ratios of positive and negative electrode currents required to produce cancellation of the voltage within scala tympani at all of the N-1 other sites. Multiple sites can be stimulated simultaneously by superposition of their respective current vectors. The method allows N independent stimulus waveforms to be delivered to each of the N electrode sites without spatial overlap. Channel interaction from current spread associated with monopolar stimulation is substantially eliminated. The method operates by inverting the spread functions of individual monopoles as measured with the other electrodes. The method was implemented and validated with data from three human subjects implanted with 22-electrode perimodiolar arrays. Results indicate that (1) focusing is realizable with realistic precision; (2) focusing comes at the cost of increased total stimulation current; (3) uncanceled voltages that arise beyond the ends of the array are weak except when stimulating the two end channels; and (4) close perimodiolar positioning of the electrodes may be important for minimizing stimulation current and sensitivity to measurement errors.

Evaluation of a new mid-scala cochlear implant electrode using microcomputed tomography.

PubMed

Frisch, Christopher D; Carlson, Matthew L; Lane, John I; Driscoll, Colin L W

2015-12-01

To investigate electrode position, depth of insertion, and electrode contact using an electrode array with a mid-scala design following round window (RW) and cochleostomy insertion. Eight fresh-frozen cadaveric bones were implanted; half via a RW approach and half through an anteroinferior cochleostomy using a styleted mid-scala electrode design. Microcomputed tomography was used to acquire oblique coronal and oblique axial reformations. Individual electrode positions along each array, insertional depth, and electrode contact were determined using National Institutes of Health Image J software. All electrodes were inserted without significant resistance. The average angular depth of insertion was 436.5° for the RW group and 422.7° for the cochleostomy group. All electrodes acquired a perimodiolar position in the proximal segment and a lateral wall position at the basal turn, regardless of approach. Electrodes distal to the basal turn demonstrated a variable location, with 78% mid scala. One cochleostomy array fractured through the interscalar partition (ISP), acquiring a scala vestibuli position. The odds ratio for either abutting the modiolus, ISP, lateral wall or floor, or fracturing through the ISP were 2.7 times more likely following a cochleostomy insertion (P = .032). The styleted mid-scala electrode design acquires a proximal perimodiolar position, a lateral wall location, as it traverses the basal turn, and most commonly a mid-scala position in the distal array. Interscalar excursion occurred in one of the cochleostomy insertions. Cochleostomy insertion is more likely to result in ultimate final electrode position adjacent to critical intracochlear structures. NA. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

Note: A resonating reflector-based optical system for motion measurement in micro-cantilever arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sathishkumar, P.; Punyabrahma, P.; Sri Muthu Mrinalini, R.

A robust, compact optical measurement unit for motion measurement in micro-cantilever arrays enables development of portable micro-cantilever sensors. This paper reports on an optical beam deflection-based system to measure the deflection of micro-cantilevers in an array that employs a single laser source, a single detector, and a resonating reflector to scan the measurement laser across the array. A strategy is also proposed to extract the deflection of individual cantilevers from the acquired data. The proposed system and measurement strategy are experimentally evaluated and demonstrated to measure motion of multiple cantilevers in an array.

Novel field cage design for the PandaX III double beta decay experiment

NASA Astrophysics Data System (ADS)

Chaiyabin, P.; Giboni, K. L.; Han, K.; Ji, X.; Juyal, P.; Kobdaj, C.; Liu, J.; Lomon, J.; Pasaja, N.; Poolcharuansin, P.; Rujirawat, S.; Songsiriritthigul, P.; Yan, Y.; Zhao, L.

2017-10-01

PandaX III is a High Pressure gaseous xenon Time Projection Chamber for Double Beta Decay detection. It will be installed deep underground in the JinPing Laboratory in Szechuan province, China. During its first phase the detector will operate with 200 kg of enriched 136Xe. The detector consists of a mesh cathode in the center of a cylindrical vessel and Micro-Bulk Micro-Megas at both ends to read out the drifting charges. The active volume is surrounded by an array of electrodes to shape the homogeneous drift field, the so called field cage. Gaseous xenon, however, is a poor dielectric. It would require in excess of 10 cm to safely stand off the HV between these electrodes and the grounded detector walls. Nearly a quarter of our available xenon would be wasted in this dead space. In a new design the electric field outside the field shaping is totally contained in a cylinder 1.6 m diameter and 2 m long. For manufacturing two 50 mm thick Acrylic plates are bend into half cylinders and bonded together. The outside surface of the cylinder is covered with a copper mesh as ground plane. The gap between field cage and detector vessel can be now reduced to 1 mm, and this gap is field free. The amount of wasted xenon is reduced by a factor 100. The field shaping electrodes and the resistive divider network are mounted on 5 mm thick Acrylic panels suspended on the inside of the field cage. This design is realized with low radioactivity materials.

Design of a bullet beam pattern of a micro ultrasound transducer (Conference Presentation)

NASA Astrophysics Data System (ADS)

Roh, Yongrae; Lee, Seongmin

2016-04-01

Ultrasonic imaging transducer is often required to compose a beam pattern of a low sidelobe level and a small beam width over a long focal region to achieve good image resolution. Normal ultrasound transducers have many channels along its azimuth, which allows easy formation of the sound beam into a desired shape. However, micro-array transducers have no control of the beam pattern along their elevation. In this work, a new method is proposed to manipulate the beam pattern by using an acoustic multifocal lens and a shaded electrode on top of the piezoelectric layer. The shading technique split an initial uniform electrode into several segments and combined those segments to compose a desired beam pattern. For a given elevation width and frequency, the optimal pattern of the split electrodes was determined by means of the OptQuest-Nonlinear Program (OQ-NLP) algorithm to achieve the lowest sidelobe level. The requirement to achieve a small beam width with a long focal region was satisfied by employing an acoustic lens of three multiple focuses. Optimal geometry of the multifocal lens such as the radius of curvature and aperture diameter for each focal point was also determined by the OQ-NLP algorithm. For the optimization, a new index was devised to evaluate the on-axis response: focal region ratio = focal region / minimum beam width. The larger was the focal region ratio, the better was the beam pattern. Validity of the design has been verified through fabricating and characterizing an experimental prototype of the transducer.

Aluminum-based one- and two-dimensional micro fin array structures: high-throughput fabrication and heat transfer testing

NASA Astrophysics Data System (ADS)

Primeaux, Philip A.; Zhang, Bin; Zhang, Xiaoman; Miller, Jacob; Meng, W. J.; KC, Pratik; Moore, Arden L.

2017-02-01

Microscale fin array structures were replicated onto surfaces of aluminum 1100 and aluminum 6061 alloy (Al1100/Al6061) sheet metals through room-temperature instrumented roll molding. Aluminum-based micro fin arrays were replicated at room temperature, and the fabrication process is one with high throughput and low cost. One-dimensional (1D) micro fin arrays were made through one-pass rolling, while two-dimensional (2D) micro fin arrays were made by sequential 90° cross rolling with the same roller sleeve. For roll molding of 1D micro fins, fin heights greater than 600 µm were achieved and were shown to be proportional to the normal load force per feature width. At a given normal load force, the fin height was further shown to scale inversely with the hardness of the sheet metal. For sequential 90° cross rolling, morphologies of roll molded 2D micro fin arrays were examined, which provided clues to understand how plastic deformation occurred under cross rolling conditions. A series of pool boiling experiments on low profile Al micro fin array structures were performed within Novec 7100, a widely used commercial dielectric coolant. Results for both horizontal and vertical surface orientations show that roll molded Al micro fin arrays can increase heat flux at fixed surface temperature as compared to un-patterned Al sheet. The present results further suggest that many factors beyond just increased surface area can influence heat transfer performance, including surface finish and the important multiphase transport mechanisms in and around the fin geometry. These factors must also be considered when designing and optimizing micro fin array structures for heat transfer applications.

Binder-free ZnO@ZnSnO3 quantum dots core-shell nanorod array anodes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Tan, Hsiang; Cho, Hsun-Wei; Wu, Jih-Jen

2018-06-01

In this work, ZnSnO3 quantum dots (QDs), instead of commonly used conductive carbon, are grown on the ZnO nanorod (NR) array to construct the binder-free ZnO@ZnSnO3 QDs core-shell NR array electrode on carbon cloth for lithium-ion battery. The ZnO@ZnSnO3 QDs core-shell NR array electrode exhibits excellent lithium storage performance with an improved cycling performance and superior rate capability compared to the ZnO NR array electrode. At a current density of 200 mAg-1, 15.8% capacity loss is acquired in the ZnO@ZnSnO3 QDs core-shell NR array electrode after 110 cycles with capacity retention of 1073 mAhg-1. Significant increases in reversible capacities from 340 to 545 mAhg-1 and from 95 to 390 mAhg-1 at current densities of 1000 and 2000 mAg-1, respectively, are achieved as the ZnO NR arrays are coated with the ZnSnO3 QD shells. The remarkably improved electrochemical performances result from that the configuration of binder-free ZnO@ZnSnO3 QDs core-shell NR array electrode not only facilitates the charge transfer through the solid electrolyte interface and the electronic/ionic conduction boundary as well as lithium ion diffusion but also effectively accommodates the volume change during repeated charge/discharge processes.

Platinum nanowire microelectrode arrays for neurostimulation applications: Fabrication, characterization, and in-vitro retinal cell stimulation

NASA Astrophysics Data System (ADS)

Whalen, John J., III

Implantable electrical neurostimulating devices are being developed for a number of applications, including artificial vision through retinal stimulation. The epiretinal prosthesis will use a two-dimensional array microelectrodes to address individual cells of the retina. MEMS fabrication processes can produce arrays of microelectrodes with these dimensions, but there are two critical issues that they cannot satisfy. One, the stimulating electrodes are the only part of the implanted electrical device that penetrate through the water impermeable package, and must do so without sacrificing hermeticity. Two, As electrode size decreases, the current density (A cm-2 ) increases, due to increased electrochemical impedance. This reduces the amount of charge that can be safely injected into the tissue. To date, MEMS processing method, cannot produce electrode arrays with good, prolonged hermetic properties. Similarly, MEMS approaches do not account for the increased impedance caused by decreased surface area. For these reasons there is a strong motivation for the development of a water-impermeable, substrate-penetrating electrode array with low electrochemical impedance. This thesis presents a stimulating electrode array fabricated from platinum nanowires using a modified electrochemical template synthesis approach. Nanowires are electrochemically deposited from ammonium hexachloroplatinate solution into lithographically patterned nanoporous anodic alumina templates to produce microarrays of platinum nanowires. The platinum nanowires penetrating through the ceramic aluminum oxide template serve as parallel electrical conduits through the water impermeable, electrically insulating substrate. Electrode impedance can be adjusted by either controlling the nanowire hydrous platinum oxide content or by partially etching the alumina template to expose additional surface area. A stepwise approach to this project was taken. First, the electrochemistry of ammonium hexachloroplatinate solution was characterized, and physical properties of electrodeposited thin films were correlated to deposition conditions used. Second, platinum nanowires were fabricated and their properties characterized, using similar deposition conditions. Third, the feasibility of fabricating platinum nanowire stimulating electrode arrays with a variety of surface structures was demonstrated. Fourth, the enhanced charge transfer characteristics of these structures were demonstrated using electrochemical techniques. Finally, retinal cell stimulation was demonstrated using electrodes from platinum nanowire arrays.

A micro-machined source transducer for a parametric array in air.

PubMed

Lee, Haksue; Kang, Daesil; Moon, Wonkyu

2009-04-01

Parametric array applications in air, such as highly directional parametric loudspeaker systems, usually rely on large radiators to generate the high-intensity primary beams required for nonlinear interactions. However, a conventional transducer, as a primary wave projector, requires a great deal of electrical power because its electroacoustic efficiency is very low due to the large characteristic mechanical impedance in air. The feasibility of a micro-machined ultrasonic transducer as an efficient finite-amplitude wave projector was studied. A piezoelectric micro-machined ultrasonic transducer array consisting of lead zirconate titanate uni-morph elements was designed and fabricated for this purpose. Theoretical and experimental evaluations showed that a micro-machined ultrasonic transducer array can be used as an efficient source transducer for a parametric array in air. The beam patterns and propagation curves of the difference frequency wave and the primary wave generated by the micro-machined ultrasonic transducer array were measured. Although the theoretical results were based on ideal parametric array models, the theoretical data explained the experimental results reasonably well. These experiments demonstrated the potential of micro-machined primary wave projector.

Inflatable belt for the application of electrode arrays

NASA Astrophysics Data System (ADS)

Sadleir, R. J.; Fox, R. A.; Turner, V. F.

2000-02-01

A prototype device for application of a multiple electrode array to the human abdomen is described and assessed. The device consists of a segmented pneumatic (PVC) belt that, upon inflation, presses electrodes onto the skin simultaneously and with predetermined relative spacings. A single belt can fit a wide range of subject sizes and is comfortable for subjects to wear. It may be useful under conditions where the time taken to attach electrodes is crucial—as in hospital emergency ward applications, and where the maintenance of constant relative electrode spacings is important. The noise performance of these electrodes was only slightly poorer than that obtained using adhesive ECG electrodes.

Chip-based device for parallel sorting, amplification, detection, and identification of nucleic acid subsequences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beer, Neil Reginald; Colston, Jr, Billy W.

An apparatus for chip-based sorting, amplification, detection, and identification of a sample having a planar substrate. The planar substrate is divided into cells. The cells are arranged on the planar substrate in rows and columns. Electrodes are located in the cells. A micro-reactor maker produces micro-reactors containing the sample. The micro-reactor maker is positioned to deliver the micro-reactors to the planar substrate. A microprocessor is connected to the electrodes for manipulating the micro-reactors on the planar substrate. A detector is positioned to interrogate the sample contained in the micro-reactors.

Radiologic and functional evaluation of electrode dislocation from the scala tympani to the scala vestibuli in patients with cochlear implants.

PubMed

Fischer, N; Pinggera, L; Weichbold, V; Dejaco, D; Schmutzhard, J; Widmann, G

2015-02-01

Localization of the electrode after cochlear implantation seems to have an impact on auditory outcome, and conebeam CT has emerged as a reliable method for visualizing the electrode array position within the cochlea. The aim of this retrospective study was to evaluate the frequency and clinical impact of scalar dislocation of various electrodes and surgical approaches and to evaluate its influence on auditory outcome. This retrospective single-center study analyzed a consecutive series of 63 cochlear implantations with various straight electrodes. The placement of the electrode array was evaluated by using multiplanar reconstructed conebeam CT images. For the auditory outcome, we compared the aided hearing thresholds and the charge units of maximum comfortable loudness level at weeks 6, 12, and 24 after implantation. In 7.9% of the cases, the electrode array showed scalar dislocation. In all cases, the electrode array penetrated the basal membrane within 45° of the electrode insertion. All 3 cases of cochleostomy were dislocated in the first 45° segment. No hearing differences were noted, but the charge units of maximum comfortable loudness level seemed to increase with time in patients with dislocations. The intracochlear dislocation rate of various straight electrodes detected by conebeam CT images is relatively low. Scalar dislocation may not negatively influence the hearing threshold but may require an increase of the necessary stimulus charge and should be reported by the radiologist. © 2015 by American Journal of Neuroradiology.

Measurement of intracellular chloride in guinea-pig vas deferens by ion analysis, 36chloride and micro-electrodes

PubMed Central

Aickin, C. Claire; Brading, Alison F.

1982-01-01

1. Cl-sensitive micro-electrodes were used to measure the intracellular Cl activity (aCli) in smooth muscle cells of the guinea-pig vas deferens. The values obtained were compared with those of intracellular Cl (Cli) found by both ion analysis and 36Cl efflux. 2. Various combinations of filling solution for recording membrane potential (Em), and type of micro-electrode were tested. The most successful, which allowed continuous recording of aCli for several hours, was a double-barrelled electrode using the reference liquid ion exchanger (RLIE; Thomas & Cohen, 1981). However, aCli measured both by simultaneous impalements of separate cells with Cl-sensitive and conventional micro-electrodes, and by double-barrelled micro-electrodes, was about 42 mM in normal Krebs solution. This is five times higher than the value from a passive distribution. ECl was about -24 mV, more than 40 mV positive to Em. 3. On complete removal of extracellular Cl (Clo), aCli fell to an apparent level of about 3 mM. If this represents interference from other anions, the maximum error in ECl measured in normal Krebs solution is 2·5 mV. Replacement of Clo caused a rapid increase in aCli. This must be caused by an active transport of Cl- ions into the cell against their electrochemical gradient. 4. The stabilized values of aCli measured at different levels of Clo agree surprisingly well with aCli estimated from ion analysis and 36Cl efflux, assuming that the intracellular activity coefficient was the same as measured in the normal Krebs solution. The relationship of aCli to Clo was hyperbolic. 5. It is concluded that Cl-sensitive micro-electrodes accurately measure aCli in smooth muscle cells. The remarkable agreement between the direct and indirect methods of measuring Cli suggests that Cl- ions are not bound to a significant extent and that the compartment seen by the micro-electrodes is probably representative of the whole cell. PMID:7108787

Ion Trap Array-Based Systems And Methods For Chemical Analysis

DOEpatents

Whitten, William B [Oak Ridge, TN; Ramsey, J Michael [Knoxville, TN

2005-08-23

An ion trap-based system for chemical analysis includes an ion trap array. The ion trap array includes a plurality of ion traps arranged in a 2-dimensional array for initially confining ions. Each of the ion traps comprise a central electrode having an aperture, a first and second insulator each having an aperture sandwiching the central electrode, and first and second end cap electrodes each having an aperture sandwiching the first and second insulator. A structure for simultaneously directing a plurality of different species of ions out from the ion traps is provided. A spectrometer including a detector receives and identifies the ions. The trap array can be used with spectrometers including time-of-flight mass spectrometers and ion mobility spectrometers.

PbS-PbSe IR detector arrays

NASA Technical Reports Server (NTRS)

Barrett, John R. (Inventor)

1986-01-01

A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chipping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

Advanced carbon manufacturing for energy and biological applications

NASA Astrophysics Data System (ADS)

Turon Teixidor, Genis

The science of miniaturization has experienced revolutionary advances during the last decades, witnessing the development of the Integrated Circuit and the emergence of MEMS and Nanotechnology. Particularly, MEMS technology has pioneered the use of non-traditional materials in microfabrication by including polymers, ceramics and composites to the well known list of metals and semiconductors. One of the latest additions to this set of materials is carbon, which represents a very important inclusion given its significance in electrochemical energy conversion systems and in applications where it is used as sensor probe material. For these applications, carbon is optimal in several counts: It has a wide electrochemical stability window, good electrical and thermal conductivity, high corrosion resistance and mechanical stability, and is available in high purity at a low cost. Furthermore carbon is biocompatible. This thesis presents several microfabricated devices that take advantage of these properties. The thesis has two clearly differentiated parts. In the first one, applications of micromachined carbon in the field of energy conversion and energy storage are presented. These applications include lithium ion micro batteries and the development of new carbon electrodes with fractal geometries. In the second part, the focus shifts to biological applications. First, the study of the interaction of living cells with micromachined carbon is presented, followed by the description of a sensor based on interdigitated nano-electrode arrays, and finally the development of the new instrumentation needed to address arrays of carbon electrodes, a multiplexed potentiostat. The underlying theme that connects all these seemingly different topics is the use of carbon microfabrication techniques in electrochemical systems.

Challenging aspects of contemporary cochlear implant electrode array design.

PubMed

Mistrík, Pavel; Jolly, Claude; Sieber, Daniel; Hochmair, Ingeborg

2017-12-01

A design comparison of current perimodiolar and lateral wall electrode arrays of the cochlear implant (CI) is provided. The focus is on functional features such as acoustic frequency coverage and tonotopic mapping, battery consumption and dynamic range. A traumacity of their insertion is also evaluated. Review of up-to-date literature. Perimodiolar electrode arrays are positioned in the basal turn of the cochlea near the modiolus. They are designed to initiate the action potential in the proximity to the neural soma located in spiral ganglion. On the other hand, lateral wall electrode arrays can be inserted deeper inside the cochlea, as they are located along the lateral wall and such insertion trajectory is less traumatic. This class of arrays targets primarily surviving neural peripheral processes. Due to their larger insertion depth, lateral wall arrays can deliver lower acoustic frequencies in manner better corresponding to cochlear tonotopicity. In fact, spiral ganglion sections containing auditory nerve fibres tuned to low acoustic frequencies are located deeper than 1 and half turn inside the cochlea. For this reason, a significant frequency mismatch might be occurring for apical electrodes in perimodiolar arrays, detrimental to speech perception. Tonal languages such as Mandarin might be therefore better treated with lateral wall arrays. On the other hand, closer proximity to target tissue results in lower psychophysical threshold levels for perimodiolar arrays. However, the maximal comfort level is also lower, paradoxically resulting in narrower dynamic range than that of lateral wall arrays. Battery consumption is comparable for both types of arrays. Lateral wall arrays are less likely to cause trauma to cochlear structures. As the current trend in cochlear implantation is the maximal protection of residual acoustic hearing, the lateral wall arrays seem more suitable for hearing preservation CI surgeries. Future development could focus on combining the advantages of both types: perimodiolar location in the basal turn extended to lateral wall location for higher turn locations.

Improving resistivity survey resolution at sites with limited spatial extent using buried electrode arrays

NASA Astrophysics Data System (ADS)

Kiflu, H.; Kruse, S.; Loke, M. H.; Wilkinson, P. B.; Harro, D.

2016-12-01

Electrical resistivity tomography (ERT) surveys are widely used in geological, environmental and engineering studies. However, the effectiveness of surface ERT surveys is limited by decreasing resolution with depth and near the ends of the survey line. Increasing the array length will increase depth of investigation, but may not be possible at urban sites where access is limited. One novel method of addressing these limitations while maintaining lateral coverage is to install an array of deep electrodes. Referred to here as the Multi-Electrode Resistivity Implant Technique (MERIT), self-driving pointed electrodes are implanted at depth below each surface electrode in an array, using direct-push technology. Optimal sequences of readings have been identified with the "Compare R" method of Wilkinson. Numerical, laboratory, and field case studies are applied to examine the effectiveness of the MERIT method, particularly for use in covered karst terrain. In the field case studies, resistivity images are compared against subsurface structure defined from borings, GPR surveys, and knowledge of prior land use. In karst terrain where limestone has a clay overburden, traditional surface resistivity methods suffer from lack of current penetration through the shallow clay layer. In these settings, the MERIT method is found to improve resolution of features between the surface and buried array, as well as increasing depth of penetration and enhancing imaging capabilities at the array ends. The method functions similar to a cross-borehole array between horizontal boreholes, and suffers from limitations common to borehole arrays. Inversion artifacts are common at depths close to the buried array, and because some readings involve high geometric factors, inversions are more susceptible to noise than traditional surface arrays. Results are improved by using errors from reciprocal measurements to weight the data during the inversion.

A Multi-Channel, Flex-Rigid ECoG Microelectrode Array for Visual Cortical Interfacing

PubMed Central

Tolstosheeva, Elena; Gordillo-González, Víctor; Biefeld, Volker; Kempen, Ludger; Mandon, Sunita; Kreiter, Andreas K.; Lang, Walter

2015-01-01

High-density electrocortical (ECoG) microelectrode arrays are promising signal-acquisition platforms for brain-computer interfaces envisioned, e.g., as high-performance communication solutions for paralyzed persons. We propose a multi-channel microelectrode array capable of recording ECoG field potentials with high spatial resolution. The proposed array is of a 150 mm2 total recording area; it has 124 circular electrodes (100, 300 and 500 μm in diameter) situated on the edges of concentric hexagons (min. 0.8 mm interdistance) and a skull-facing reference electrode (2.5 mm2 surface area). The array is processed as a free-standing device to enable monolithic integration of a rigid interposer, designed for soldering of fine-pitch SMD-connectors on a minimal assembly area. Electrochemical characterization revealed distinct impedance spectral bands for the 100, 300 and 500 μm-type electrodes, and for the array's own reference. Epidural recordings from the primary visual cortex (V1) of an awake Rhesus macaque showed natural electrophysiological signals and clear responses to standard visual stimulation. The ECoG electrodes of larger surface area recorded signals with greater spectral power in the gamma band, while the skull-facing reference electrode provided higher average gamma power spectral density (γPSD) than the common average referencing technique. PMID:25569757

Carbon Nanofiber Electrode Array for Neurochemical Monitoring

NASA Technical Reports Server (NTRS)

Koehne, Jessica E.

2017-01-01

A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report using vertically aligned CNF as neurotransmitter recording electrodes for application in a smart deep brain stimulation (DBS) device. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

Advances in selective activation of muscles for non-invasive motor neuroprostheses.

PubMed

Koutsou, Aikaterini D; Moreno, Juan C; Del Ama, Antonio J; Rocon, Eduardo; Pons, José L

2016-06-13

Non-invasive neuroprosthetic (NP) technologies for movement compensation and rehabilitation remain with challenges for their clinical application. Two of those major challenges are selective activation of muscles and fatigue management. This review discusses how electrode arrays improve the efficiency and selectivity of functional electrical stimulation (FES) applied via transcutaneous electrodes. In this paper we review the principles and achievements during the last decade on techniques for artificial motor unit recruitment to improve the selective activation of muscles. We review the key factors affecting the outcome of muscle force production via multi-pad transcutaneous electrical stimulation and discuss how stimulation parameters can be set to optimize external activation of body segments. A detailed review of existing electrode array systems proposed by different research teams is also provided. Furthermore, a review of the targeted applications of existing electrode arrays for control of upper and lower limb NPs is provided. Eventually, last section demonstrates the potential of electrode arrays to overcome the major challenges of NPs for compensation and rehabilitation of patient-specific impairments.

Effects of discrete-electrode arrangement on traveling-wave electroosmotic pumping

NASA Astrophysics Data System (ADS)

Liu, Weiyu; Shao, Jinyou; Ren, Yukun; Wu, Yupan; Wang, Chunhui; Ding, Haitao; Jiang, Hongyuan; Ding, Yucheng

2016-09-01

Traveling-wave electroosmotic (TWEO) pumping arises from the action of an imposed traveling-wave (TW) electric field on its own induced charge in the diffuse double layer, which is formed on top of an electrode array immersed in electrolyte solutions. Such a traveling field can be merely realized in practice by a discrete electrode array upon which the corresponding voltages of correct phase are imposed. By employing the theory of linear and weakly nonlinear double-layer charging dynamics, a physical model incorporating both the nonlinear surface capacitance of diffuse layer and Faradaic current injection is developed herein in order to quantify the changes in TWEO pumping performance from a single-mode TW to discrete electrode configuration. Benefiting from the linear analysis, we investigate the influence of using discrete electrode array to create the TW signal on the resulting fluid motion, and several approaches are suggested to improve the pumping performance. In the nonlinear regime, our full numerical analysis considering the intervening isolation spacing indicates that a practical four-phase discrete electrode configuration of equal electrode and gap width exhibits stronger nonlinearity than expected from the idealized pump applied with a single-mode TW in terms of voltage-dependence of the ideal pumping frequency and peak flow rate, though it has a much lower pumping performance. For model validation, pumping of electrolytes by TWEO is achieved over a confocal spiral four-phase electrode array covered by an insulating microchannel; measurement of flow velocity indicates the modified nonlinear theory considering moderate Faradaic conductance is indeed a more accurate physical description of TWEO. These results offer useful guidelines for designing high-performance TWEO microfluidic pumps with discrete electrode array.

Effects of low charge injection densities on corrosion responses of pulsed 316LVM stainless steel electrodes.

PubMed

Riedy, L W; Walter, J S

1996-06-01

The safe charge injection density for pulsing of 316LVM electrodes has been reported to be 40 microC/cm2. However, only 20 microC/cm2 is available for nonfaradic charge transfer and double layer charge injection. Therefore, we evaluated long term pulsing at 20 microC/cm2 with capacitor coupling.

Initial Operative Experience and Short Term Hearing Preservation Results with a Mid-Scala Cochlear Implant Electrode Array

PubMed Central

Svrakic, Maja; Roland, J. Thomas; McMenomey, Sean O.; Svirsky, Mario A.

2016-01-01

OBJECTIVE To describe our initial operative experience and hearing preservation results with the Advanced Bionics (AB) Mid Scala Electrode (MSE) STUDY DESIGN Retrospective review. SETTING Tertiary referral center. PATIENTS Sixty-three MSE implants in pediatric and adult patients were compared to age- and gender-matched 1j electrode implants from the same manufacturer. All patients were severe to profoundly deaf. INTERVENTION Cochlear implantation with either the AB 1j electrode or the AB MSE. MAIN OUTCOME MEASURES The MSE and 1j electrode were compared in their angular depth of insertion (aDOI) and pre- to post-operative change in hearing thresholds. Hearing preservation was analyzed as a function of aDOI. Secondary outcome measures included operative time, incidence of abnormal intraoperative impedance and telemetry values, and incidence of postsurgical complications. RESULTS Depth of insertion was similar for both electrodes, but was more consistent for the MSE array and more variable for the 1j array. Patients with MSE electrodes had better hearing preservation. Thresholds shifts at four audiometric frequencies ranging from 250 to 2,000 Hz were 10 dB, 7 dB, 2 dB and 6 dB smaller for the MSE electrode than for the 1j (p<0.05). Hearing preservation at low frequencies was worse with deeper insertion, regardless of array. Secondary outcome measures were similar for both electrodes. CONCLUSIONS The MSE electrode resulted in more consistent insertion depth and somewhat better hearing preservation than the 1j electrode. Differences in other surgical outcome measures were small or unlikely to have a meaningful effect. PMID:27755356

A low-cost, scalable, current-sensing digital headstage for high channel count μECoG.

PubMed

Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Sertac Artan, N; Froemke, Robert C; Viventi, Jonathan

2017-04-01

High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 d. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but also resulted in a small, light headstage that can easily be scaled to record from hundreds of channels.

A low-cost, scalable, current-sensing digital headstage for high channel count μECoG

NASA Astrophysics Data System (ADS)

Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Sertac Artan, N.; Froemke, Robert C.; Viventi, Jonathan

2017-04-01

Objective. High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. Approach. We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. Main results. The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 d. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. Significance. We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but also resulted in a small, light headstage that can easily be scaled to record from hundreds of channels.

A low-cost, scalable, current-sensing digital headstage for high channel count μECoG

PubMed Central

Trumpis, Michael; Insanally, Michele; Zou, Jialin; Elsharif, Ashraf; Ghomashchi, Ali; Artan, N. Sertac; Froemke, Robert C.; Viventi, Jonathan

2017-01-01

Objective High channel count electrode arrays allow for the monitoring of large-scale neural activity at high spatial resolution. Implantable arrays featuring many recording sites require compact, high bandwidth front-end electronics. In the present study, we investigated the use of a small, light weight, and low cost digital current-sensing integrated circuit for acquiring cortical surface signals from a 61-channel micro-electrocorticographic (μECoG) array. Approach We recorded both acute and chronic μECoG signal from rat auditory cortex using our novel digital current-sensing headstage. For direct comparison, separate recordings were made in the same anesthetized preparations using an analog voltage headstage. A model of electrode impedance explained the transformation between current- and voltage-sensed signals, and was used to reconstruct cortical potential. We evaluated the digital headstage using several metrics of the baseline and response signals. Main results The digital current headstage recorded neural signal with similar spatiotemporal statistics and auditory frequency tuning compared to the voltage signal. The signal-to-noise ratio of auditory evoked responses (AERs) was significantly stronger in the current signal. Stimulus decoding based on true and reconstructed voltage signals were not significantly different. Recordings from an implanted system showed AERs that were detectable and decodable for 52 days. The reconstruction filter mitigated the thermal current noise of the electrode impedance and enhanced overall SNR. Significance We developed and validated a novel approach to headstage acquisition that used current-input circuits to independently digitize 61 channels of μECoG measurements of the cortical field. These low-cost circuits, intended to measure photo-currents in digital imaging, not only provided a signal representing the local cortical field with virtually the same sensitivity and specificity as a traditional voltage headstage but also resulted in a small, light headstage that can easily be scaled to record from hundreds of channels. PMID:28102827

Characterization of flexible ECoG electrode arrays for chronic recording in awake rats

PubMed Central

Yeager, John D.; Phillips, Derrick J.; Rector, David M.; Bahr, David F.

2008-01-01

We developed a 64 channel flexible polyimide ECoG electrode array and characterized its performance for long term implantation, chronic cortical recording and high resolution mapping of surface evoked potentials in awake rats. To achieve the longest possible recording periods, the flexibility of the electrode array, adhesion between the metals and carrier substrate, and biocompatibility was critical for maintaining the signal integrity. Experimental testing of thin film adhesion was applied to a gold – polyimide system in order to characterize relative interfacial fracture energies for several different adhesion layers, yielding an increase in overall device reliability. We tested several different adhesion techniques including: gold alone without an adhesion layer, titanium-tungsten, tantalum and chromium. We found the titanium-tungsten to be a suitable adhesion layer considering the biocompatibility requirements as well as stability and delamination resistance. While chromium and tantalum produced stronger gold adhesion, concerns over biocompatibility of these materials require further testing. We implanted the polyimide ECoG electrode arrays through a slit made in the skull of rats and recorded cortical surface evoked responses. The arrays performed reliably over a period of at least 100 days and signals compared well with traditional screw electrodes, with better high frequency response characteristics. Since the ultimate goal of chronically implanted electrode arrays is for neural prosthetic devices that need to last many decades, other adhesion layers that would prove safe for implantation may be tested in the same way in order to improve the device reliability. PMID:18640155

Microfabricated Patch Clamp Electrodes for Improved Ion Channel Protein Measurements

NASA Astrophysics Data System (ADS)

Klemic, James; Klemic, Kathryn; Reed, Mark; Sigworth, Frederick

2002-03-01

Ion channels are trans-membrane proteins that underlie many cell functions including hormone and neurotransmitter release, muscle contraction and cell signaling cascades. Ion channel proteins are commonly characterized via the patch clamp method in which an extruded glass tube containing ionic solution, manipulated by an expert technician, is brought into contact with a living cell to record ionic current through the cell membrane. Microfabricated planar patch electrodes, micromolded in the silicone elastomer poly-dimethylsiloxane (PDMS) from microlithographically patterned structures, have been developed that improve on this method. Microfabrication techniques allow arrays of patch electrodes to be fabricated, increasing the throughput of the measurement technique. Planar patch electrodes readily allow the automation of cell sealing, further increasing throughput. Microfabricated electrode arrays may be readily integrated with microfluidic structures to allow fast, in situ solution exchange. Miniaturization of the electrode geometry should increase both the signal to noise and the bandwidth of the measurement. Microfabricated patch electrode arrays have been fabricated and measurements have been taken.

Contamination Study of Micro Pulsed Plasma Thruster

DTIC Science & Technology

2008-03-01

missions ranging from nano -satellites to large spacecrafts requiring precision placement1. As an unfortunate side effect, the exhaust plume induces...the electrodes9. The electrodes have often been arranged coaxially . The system consists of electrodes, capacitors as energy storage units, a spark...increasing interest in the so-called micro- and nano -satellites, which are highly maneuverable and have lower cost. These small satellites are aimed to

Fabrication of micro-lens array on convex surface by meaning of micro-milling

NASA Astrophysics Data System (ADS)

Zhang, Peng; Du, Yunlong; Wang, Bo; Shan, Debin

2014-08-01

In order to develop the application of the micro-milling technology, and to fabricate ultra-precision optical surface with complex microstructure, in this paper, the primary experimental research on micro-milling complex microstructure array is carried out. A complex microstructure array surface with vary parameters is designed, and the mathematic model of the surface is set up and simulated. For the fabrication of the designed microstructure array surface, a micro three-axis ultra-precision milling machine tool is developed, aerostatic guideway drove directly by linear motor is adopted in order to guarantee the enough stiffness of the machine, and novel numerical control strategy with linear encoders of 5nm resolution used as the feedback of the control system is employed to ensure the extremely high motion control accuracy. With the help of CAD/CAM technology, convex micro lens array on convex spherical surface with different scales on material of polyvinyl chloride (PVC) and pure copper is fabricated using micro tungsten carbide ball end milling tool based on the ultra-precision micro-milling machine. Excellent nanometer-level micro-movement performance of the axis is proved by motion control experiment. The fabrication is nearly as the same as the design, the characteristic scale of the microstructure is less than 200μm and the accuracy is better than 1μm. It prove that ultra-precision micro-milling technology based on micro ultra-precision machine tool is a suitable and optional method for micro manufacture of microstructure array surface on different kinds of materials, and with the development of micro milling cutter, ultraprecision micro-milling complex microstructure surface will be achieved in future.

Double interconnection fuel cell array

DOEpatents

Draper, R.; Zymboly, G.E.

1993-12-28

A fuel cell array is made, containing number of tubular, elongated fuel cells which are placed next to each other in rows (A, B, C, D), where each cell contains inner electrodes and outer electrodes, with solid electrolyte between the electrodes, where the electrolyte and outer electrode are discontinuous, having two portions, and providing at least two opposed discontinuities which contain at least two oppositely opposed interconnections contacting the inner electrode, each cell having only three metallic felt electrical connectors which contact surrounding cells, where each row is electrically connected to the other. 5 figures.

Electrochemical detection of dopamine in the presence of ascorbic acid using graphene modified electrodes.

PubMed

Kim, Yang-Rae; Bong, Sungyool; Kang, Yeon-Joo; Yang, Yongtak; Mahajan, Rakesh Kumar; Kim, Jong Seung; Kim, Hasuck

2010-06-15

Dopamine plays a significant role in the function of human metabolism. It is important to develop sensitive sensor for the determination of dopamine without the interference by ascorbic acid. This paper reports the synthesis of graphene using a modified Hummer's method and its application for the electrochemical detection of dopamine. Electrochemical measurements were performed at glassy carbon electrode modified with graphene via drop-casting method. Cyclic voltammogram of ferri/ferrocyanide redox couple at graphene modified electrode showed an increased current intensity compared with glassy carbon electrode and graphite modified electrode. The decrease of charge transfer resistance was also analyzed by electrochemical impedance spectroscopy. The capacity of graphene modified electrode for selective detection of dopamine was confirmed in a sufficient amount of ascorbic acid (1 mM). The observed linear range for the determination of dopamine concentration was from 4 microM to 100 microM. The detection limit was estimated to be 2.64 microM. Copyright 2010 Elsevier B.V. All rights reserved.

Manufacturing PDMS micro lens array using spin coating under a multiphase system

NASA Astrophysics Data System (ADS)

Sun, Rongrong; Yang, Hanry; Rock, D. Mitchell; Danaei, Roozbeh; Panat, Rahul; Kessler, Michael R.; Li, Lei

2017-05-01

The development of micro lens arrays has garnered much interest due to increased demand of miniaturized systems. Traditional methods for manufacturing micro lens arrays have several shortcomings. For example, they require expensive facilities and long lead time, and traditional lens materials (i.e. glass) are typically heavy, costly and difficult to manufacture. In this paper, we explore a method for manufacturing a polydimethylsiloxane (PDMS) micro lens array using a simple spin coating technique. The micro lens array, formed under an interfacial tension dominated system, and the influence of material properties and process parameters on the fabricated lens shape are examined. The lenses fabricated using this method show comparable optical properties—including surface finish and image quality—with a reduced cost and manufacturing lead time.

BiOCl micro-assembles consisting of ultrafine nanoplates: A high performance electro-catalyst for air electrode of Al-air batteries

NASA Astrophysics Data System (ADS)

Yuan, Jinlan; Wang, Jin; She, Yiyi; Hu, Jing; Tao, Pengpeng; Lv, Fucong; Lu, Zhouguang; Gu, Yingying

2014-10-01

BiOCl micro-assembles appearing spherical and plate-like in shape consisting of ultrafine nanoplates were successfully synthesized by a simple hydrothermal method. The obtained BiOCl micro-assembles were characterized as oxygen reduction reaction (ORR) catalyst for air electrode of aluminum air batteries by using linear polarization and constant-current discharge techniques. The effect of precursor concentration on the electrochemical properties of the air electrodes based on the synthesized BiOCl micro-assembles was intensively investigated. The results demonstrated that the BiOCl catalyst exhibited promising ORR performance. Koutecky-Levich analysis indicated that a two-electron reaction was favored for the ORR mechanism of the BiOCl (0.18) sample.

Durability of Hearing Preservation after Cochlear Implantation with Conventional-Length Electrodes and Scala Tympani Insertion

PubMed Central

Sweeney, Alex D.; Hunter, Jacob B.; Carlson, Matthew L.; Rivas, Alejandro; Bennett, Marc L.; Gifford, Rene H.; Noble, Jack H.; Haynes, David S.; Labadie, Robert F.; Wanna, George B.

2016-01-01

Objectives To analyze factors that influence hearing preservation over time in cochlear implant recipients with conventional-length electrode arrays located entirely within the scala tympani. Study Design Case series with planned chart review. Setting Single tertiary academic referral center. Subjects and Methods A retrospective review was performed to analyze a subgroup of cochlear implant recipients with residual acoustic hearing. Patients were included in the study only if their electrode arrays remained fully in the scala tympani after insertion and serviceable acoustic hearing (≤80 dB at 250 Hz) was preserved. Electrode array location was verified through a validated radiographic assessment tool. Patients with <6 months of audiologic follow-up were excluded. The main outcome measure was change in acoustic hearing thresholds from implant activation to the last available follow-up. Results A total of 16 cases met inclusion criteria (median age, 70.6 years; range, 29.4–82.2; 50% female). The average follow-up was 18.0 months (median, 16.1; range, 6.2–36.4). Patients with a lateral wall electrode array were more likely to have stable acoustic thresholds over time (P < .05). Positive correlations were seen between continued hearing loss following activation and larger initial postoperative acoustic threshold shifts, though statistical significance was not achieved. Age, sex, and noise exposure had no significant influence on continued hearing preservation over time. Conclusions To control for hearing loss associated with inter-scalar excursion during cochlear implantation, the present study evaluated patients only with conventional electrode arrays located entirely within the scala tympani. In this group, the style of electrode array may influence residual hearing preservation over time. PMID:26908553

Durability of Hearing Preservation after Cochlear Implantation with Conventional-Length Electrodes and Scala Tympani Insertion.

PubMed

Sweeney, Alex D; Hunter, Jacob B; Carlson, Matthew L; Rivas, Alejandro; Bennett, Marc L; Gifford, Rene H; Noble, Jack H; Haynes, David S; Labadie, Robert F; Wanna, George B

2016-05-01

To analyze factors that influence hearing preservation over time in cochlear implant recipients with conventional-length electrode arrays located entirely within the scala tympani. Case series with planned chart review. Single tertiary academic referral center. A retrospective review was performed to analyze a subgroup of cochlear implant recipients with residual acoustic hearing. Patients were included in the study only if their electrode arrays remained fully in the scala tympani after insertion and serviceable acoustic hearing (≤80 dB at 250 Hz) was preserved. Electrode array location was verified through a validated radiographic assessment tool. Patients with <6 months of audiologic follow-up were excluded. The main outcome measure was change in acoustic hearing thresholds from implant activation to the last available follow-up. A total of 16 cases met inclusion criteria (median age, 70.6 years; range, 29.4-82.2; 50% female). The average follow-up was 18.0 months (median, 16.1; range, 6.2-36.4). Patients with a lateral wall electrode array were more likely to have stable acoustic thresholds over time (P < .05). Positive correlations were seen between continued hearing loss following activation and larger initial postoperative acoustic threshold shifts, though statistical significance was not achieved. Age, sex, and noise exposure had no significant influence on continued hearing preservation over time. To control for hearing loss associated with interscalar excursion during cochlear implantation, the present study evaluated patients only with conventional electrode arrays located entirely within the scala tympani. In this group, the style of electrode array may influence residual hearing preservation over time. © American Academy of Otolaryngology—Head and Neck Surgery Foundation 2016.

High power density fuel cell comprising an array of microchannels

DOEpatents

Morse, Jeffrey D.; Upadhye, Ravindra S.; Spadaccini, Christopher M.; Park, Hyung Gyu

2013-10-15

A fuel cell according to one embodiment includes a porous electrolyte support structure defining an array of microchannels, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and oxidant electrodes formed along other of the microchannels. A method of making a fuel cell according to one embodiment includes forming an array of walls defining microchannels therebetween using at least one of molding, stamping, extrusion, injection and electrodeposition; processing the walls to make the walls porous, thereby creating a porous electrolyte support structure; forming anode electrodes along some of the microchannels; and forming cathode electrodes along other of the microchannels. Additional embodiments are also disclosed.

Theoretical Model of Electrode Polarization and AC Electroosmotic Fluid Flow in Planar Electrode Arrays.

PubMed

Scott, Matthew; Kaler, Karan V. I. S.; Paul, Reginald

2001-06-15

Strong frequency-dependent fluid flow has been observed near the surface of microelectrode arrays. Modeling this phenomenon has proven to be difficult, with existing theories unable to account for the qualitative trend observed in the frequency spectra of this flow. Using recent electrode polarization results, a more comprehensive model of the double layer on the electrode surface is used to obtain good theoretical agreement with experimental data. Copyright 2001 Academic Press.

A high performance three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection.

PubMed

Xu, Chenlong; Song, Zhiqian; Xiang, Qun; Jin, Jian; Feng, Xinjian

2016-04-14

We describe here a high performance oxygen-rich three-phase enzyme electrode based on superhydrophobic mesoporous silicon nanowire arrays for glucose detection. We demonstrate that its linear detection upper limit is 30 mM, more than 15 times higher than that can be obtained on the normal enzyme-electrode. Notably, the three-phase enzyme electrode output is insensitive to the significant oxygen level fluctuation in analyte solution.

Focal Adhesion Induction at the Tip of a Functionalized Nanoelectrode

PubMed Central

Fuentes, Daniela E.; Bae, Chilman; Butler, Peter J.

2012-01-01

Cells dynamically interact with their physical micro-environment through the assembly of nascent focal contacts and focal adhesions. The dynamics and mechanics of these contact points are controlled by transmembrane integrins and an array of intracellular adaptor proteins. In order to study the mechanics and dynamics of focal adhesion assembly, we have developed a technique for the timed induction of a nascent focal adhesion. Bovine aortic endothelial cells were approached at the apical surface by a nanoelectrode whose position was controlled with a resolution of 10s of nanometers using changes in electrode current to monitor distance from the cell surface. Since this probe was functionalized with fibronectin, a focal contact formed at the contact location. Nascent focal adhesion assembly was confirmed using time-lapse confocal fluorescent images of red fluorescent protein (RFP) – tagged talin, an adapter protein that binds to activated integrins. Binding to the cell was verified by noting a lack of change of electrode current upon retraction of the electrode. This study demonstrates that functionalized nanoelectrodes can enable precisely-timed induction and 3-D mechanical manipulation of focal adhesions and the assay of the detailed molecular kinetics of their assembly. PMID:22247742

Micro-sonicator for spore lysis

DOEpatents

Miles, Robin R.; Belgrader, Phillip; Nasarabadi, Shanavaz L.

2000-01-01

A micro-sonicator for spore lysis. Using micromachining technology, the micro-sonicator uses ultrasonic excitation of spores to perform spore and cell lysis. The micro-sonicator comprises a container with a cavity therein for retaining the sample in an ultrasonic transmission medium, the cavity being closed by a silicon membrane to which an electrode and piezoelectric material are attached, with the electrode and piezoelectric material being electrically connected to an AC signal generator which causes the membrane to flex and vibrate at the frequency of the applied voltage.

Arrays of Very Small Voltammetric Electrodes Based on Reticulated Vitreous Carbon.

DTIC Science & Technology

1983-10-14

1H D-fli34 73ifARRAYS OF VERY SMALL YOLTAMMETRIC ELECTRODES BA5ED ON i/i RETICULATED VITREOUS CARBON (U) STATE UNIV OF NEW YORK I AT BUFFALO AMHERST N...PEIOiUD COVI[R9 1^. Arrays of Very Small Voltametric Electrodes 0 Based on Reticulated Vitreous Carbon - S. PRFROG OG. REPORT NUM A 7. AUTNOR) 0...Cofigi nueu eav’e,o *ee i necesaery and Iden lly by block number) L.Uj Reticulated vitreous carbon ; microelectrodes; nonlinear diffusion; vol tammetry

Method of fabricating a PbS-PbSe IR detector array

NASA Technical Reports Server (NTRS)

Barrett, John R. (Inventor)

1987-01-01

A silicon wafer is provided which does not employ individually bonded leads between the IR sensitive elements and the input stages of multiplexers. The wafer is first coated with lead selenide in a first detector array area and is thereafter coated with lead sulfide within a second detector array area. The described steps result in the direct chemical deposition of lead selenide and lead sulfide upon the silicon wafer to eliminate individual wire bonding, bumping, flip chiping, planar interconnecting methods of connecting detector array elements to silicon chip circuitry, e.g., multiplexers, to enable easy fabrication of very long arrays. The electrode structure employed, produces an increase in the electrical field gradient between the electrodes for a given volume of detector material, relative to conventional electrode configurations.

Tunable liquid microlens arrays in electrode-less configuration and their accurate characterization by interference microscopy.

PubMed

Miccio, L; Finizio, A; Grilli, S; Vespini, V; Paturzo, M; De Nicola, S; Ferraro, Pietro

2009-02-16

A special class of tunable liquid microlenses is presented here. The microlenses are generated by an electrowetting effect under an electrode-less configuration and they exhibit two different regimes that are named here as separated lens regime (SLR) and wave-like lens regime (WLR). The lens effect is induced by the pyroelectricity of polar dielectric crystals, as was proved in principle in a previous work by the same authors (S. Grilli et al., Opt. Express 16, 8084, 2008). Compared to that work, the improvements to the experimental set-up and procedure allow to reveal the two lens regimes which exhibit different optical properties. A digital holography technique is used to reconstruct the transmitted wavefront during focusing and a focal length variation in the millimetre range is observed. The tunability of such microlenses could be of great interest to the field of micro-optics thanks to the possibility to achieve focus tuning without moving parts and thus favouring the miniaturization of the optical systems.

A sensitive electrochemical immunosensor for label-free detection of Zika-virus protein.

PubMed

Kaushik, Ajeet; Yndart, Adriana; Kumar, Sanjeev; Jayant, Rahul Dev; Vashist, Arti; Brown, Ashley N; Li, Chen-Zhong; Nair, Madhavan

2018-06-26

This work, as a proof of principle, presents a sensitive and selective electrochemical immunosensor for Zika-virus (ZIKV)-protein detection using a functionalized interdigitated micro-electrode of gold (IDE-Au) array. A miniaturized IDE-Au immunosensing chip was prepared via immobilization of ZIKV specific envelop protein antibody (Zev-Abs) onto dithiobis(succinimidyl propionate) i.e., (DTSP) functionalized IDE-Au (electrode gap/width of 10 µm). Electrochemical impedance spectroscopy (EIS) was performed to measure the electrical response of developed sensing chip as a function of ZIKV-protein concentrations. The results of EIS studies confirmed that sensing chip detected ZIKV-protein selectively and exhibited a detection range from 10 pM to 1 nM and a detection limit of 10 pM along with a high sensitivity of 12 kΩM -1 . Such developed ZIKV immune-sensing chip can be integrated with a miniaturized potentiostat (MP)-interfaced with a smartphone for rapid ZIKV-infection detection required for early stage diagnostics at point-of-care application.

Round window electrode insertion potentiates retention in the scala tympani.

PubMed

Connor, Stephen E J; Holland, N Julian; Agger, Andreas; Leong, Annabelle C; Varghese, Re Ajay; Jiang, Dan; Fitzgerald O'Connor, Alec

2012-09-01

The round window membrane (RWM)-intentioned approach is superior to the traditional bony cochleostomy (BC) approach in obtaining electrode placement within the scala tympani (ST). Cochlear implant outcome is influenced by several factors, including optimal placement and retention of the electrode array within the ST. The present study aimed to assess whether the RWM route is superior to a traditional BC for placement and retention of the electrode array in the ST. This was a prospective consecutive non-randomized comparison study. All patients were implanted with the Advanced Bionics 1J electrode array. The RWM approach (n = 32) was compared with a traditional BC group (n = 33). The outcome measure was the electrode position as judged within the scalar chambers at four points along the basal turn using postoperative computed tomography (CT). When the mean position scores were compared, the RWM-intentioned group had significantly more electrodes directed towards the ST compartment than the BC group (p < 0.001). The RWM electrodes achieved 94% ST retention compared with 64% for the BC group (p < 0.05). All electrodes stayed in the ST in the RWM group, whereas in the BC group 9% crossed from the ST to the scala vestibuli.

Oriented nanotube electrodes for lithium ion batteries and supercapacitors

DOEpatents

Frank, Arthur J.; Zhu, Kai; Wang, Qing

2013-03-05

An electrode having an oriented array of multiple nanotubes is disclosed. Individual nanotubes have a lengthwise inner pore defined by interior tube walls which extends at least partially through the length of the nanotube. The nanotubes of the array may be oriented according to any identifiable pattern. Also disclosed is a device featuring an electrode and methods of fabrication.

A Multi-Functional Microelectrode Array Featuring 59760 Electrodes, 2048 Electrophysiology Channels, Stimulation, Impedance Measurement and Neurotransmitter Detection Channels.

PubMed

Dragas, Jelena; Viswam, Vijay; Shadmani, Amir; Chen, Yihui; Bounik, Raziyeh; Stettler, Alexander; Radivojevic, Milos; Geissler, Sydney; Obien, Marie; Müller, Jan; Hierlemann, Andreas

2017-06-01

Biological cells are characterized by highly complex phenomena and processes that are, to a great extent, interdependent. To gain detailed insights, devices designed to study cellular phenomena need to enable tracking and manipulation of multiple cell parameters in parallel; they have to provide high signal quality and high spatiotemporal resolution. To this end, we have developed a CMOS-based microelectrode array system that integrates six measurement and stimulation functions, the largest number to date. Moreover, the system features the largest active electrode array area to date (4.48×2.43 mm 2 ) to accommodate 59,760 electrodes, while its power consumption, noise characteristics, and spatial resolution (13.5 μm electrode pitch) are comparable to the best state-of-the-art devices. The system includes: 2,048 action-potential (AP, bandwidth: 300 Hz to 10 kHz) recording units, 32 local-field-potential (LFP, bandwidth: 1 Hz to 300 Hz) recording units, 32 current recording units, 32 impedance measurement units, and 28 neurotransmitter detection units, in addition to the 16 dual-mode voltage-only or current/voltage-controlled stimulation units. The electrode array architecture is based on a switch matrix, which allows for connecting any measurement/stimulation unit to any electrode in the array and for performing different measurement/stimulation functions in parallel.

\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}${\\mbi{\\mu }}$\\end{document}-Foil Polymer Electrode Array for Intracortical Neural Recordings

PubMed Central

Köhler, Per; Granmo, Marcus; Schouenborg, Jens; Bengtsson, Martin; Wallman, Lars

2014-01-01

We have developed a multichannel electrode array—termed \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}\\(\\mu \\) \\end{document}-foil—that comprises ultrathin and flexible electrodes protruding from a thin foil at fixed distances. In addition to allowing some of the active sites to reach less compromised tissue, the barb-like protrusions that also serves the purpose of anchoring the electrode array into the tissue. This paper is an early evaluation of technical aspects and performance of this electrode array in acute in vitro/in vivo experiments. The interface impedance was reduced by up to two decades by electroplating the active sites with platinum black. The platinum black also allowed for a reduced phase lag for higher frequency components. The distance between the protrusions of the electrode array was tailored to match the architecture of the rat cerebral cortex. In vivo acute measurements confirmed a high signal-to-noise ratio for the neural recordings, and no significant crosstalk between recording channels. PMID:27170864

Micro supercapacitors based on a 3D structure with symmetric graphene or activated carbon electrodes

NASA Astrophysics Data System (ADS)

Li, Siwei; Wang, Xiaohong; Xing, Hexin; Shen, Caiwei

2013-11-01

This paper presents three-dimensional (3D) micro supercapacitors with thick interdigital electrodes supported and separated by SU-8. Nanoporous carbon materials including graphene and activated carbon (AC) are used as active materials in self-supporting composites to build the electrodes. The SU-8 separators provide mechanical support for thick electrodes and allow a considerable amount of material to be loaded in a limited footprint area. The prototypes have been accomplished by a simple microelectromechanical systems (MEMS) fabrication process and sealed by polydimethylsiloxane (PDMS) caps with ionic liquid electrolytes injected into the electrode area. Electrochemical tests demonstrate that the graphene-based prototype with 100 µm thick electrodes shows good power performance and provides a considerable specific capacitance of about 60 mF cm-2. Two AC-based prototypes show larger capacitance of 160 mF cm-2 and 311 mF cm-2 with 100 µm and 200 µm thick electrodes respectively, because of higher volume density of the material. The results demonstrate that both thick 3D electrode structure and volume capacitance of the electrode material are key factors for high-performance micro supercapacitors, which can be potentially used in specific applications such as power suppliers and storage components for harvesters.

Flexible Organic Electronics for Use in Neural Sensing

PubMed Central

Bink, Hank; Lai, Yuming; Saudari, Sangameshwar R.; Helfer, Brian; Viventi, Jonathan; Van der Spiegel, Jan; Litt, Brian; Kagan, Cherie

2016-01-01

Recent research in brain-machine interfaces and devices to treat neurological disease indicate that important network activity exists at temporal and spatial scales beyond the resolution of existing implantable devices. High density, active electrode arrays hold great promise in enabling high-resolution interface with the brain to access and influence this network activity. Integrating flexible electronic devices directly at the neural interface can enable thousands of multiplexed electrodes to be connected using many fewer wires. Active electrode arrays have been demonstrated using flexible, inorganic silicon transistors. However, these approaches may be limited in their ability to be cost-effectively scaled to large array sizes (8×8 cm). Here we show amplifiers built using flexible organic transistors with sufficient performance for neural signal recording. We also demonstrate a pathway for a fully integrated, amplified and multiplexed electrode array built from these devices. PMID:22255558

Flexible, foldable, actively multiplexed, high-density electrode array for mapping brain activity in vivo.

PubMed

Viventi, Jonathan; Kim, Dae-Hyeong; Vigeland, Leif; Frechette, Eric S; Blanco, Justin A; Kim, Yun-Soung; Avrin, Andrew E; Tiruvadi, Vineet R; Hwang, Suk-Won; Vanleer, Ann C; Wulsin, Drausin F; Davis, Kathryn; Gelber, Casey E; Palmer, Larry; Van der Spiegel, Jan; Wu, Jian; Xiao, Jianliang; Huang, Yonggang; Contreras, Diego; Rogers, John A; Litt, Brian

2011-11-13

Arrays of electrodes for recording and stimulating the brain are used throughout clinical medicine and basic neuroscience research, yet are unable to sample large areas of the brain while maintaining high spatial resolution because of the need to individually wire each passive sensor at the electrode-tissue interface. To overcome this constraint, we developed new devices that integrate ultrathin and flexible silicon nanomembrane transistors into the electrode array, enabling new dense arrays of thousands of amplified and multiplexed sensors that are connected using fewer wires. We used this system to record spatial properties of cat brain activity in vivo, including sleep spindles, single-trial visual evoked responses and electrographic seizures. We found that seizures may manifest as recurrent spiral waves that propagate in the neocortex. The developments reported here herald a new generation of diagnostic and therapeutic brain-machine interface devices.

Transdermal delivery of therapeutic agent

NASA Technical Reports Server (NTRS)

Kwiatkowski, Krzysztof C. (Inventor); Hayes, Ryan T. (Inventor); Magnuson, James W. (Inventor); Giletto, Anthony (Inventor)

2008-01-01

A device for the transdermal delivery of a therapeutic agent to a biological subject that includes a first electrode comprising a first array of electrically conductive microprojections for providing electrical communication through a skin portion of the subject to a second electrode comprising a second array of electrically conductive microprojections. Additionally, a reservoir for holding the therapeutic agent surrounding the first electrode and a pulse generator for providing an exponential decay pulse between the first and second electrodes may be provided. A method includes the steps of piercing a stratum corneum layer of skin with two arrays of conductive microprojections, encapsulating the therapeutic agent into biocompatible charged carriers, surrounding the conductive microprojections with the therapeutic agent, generating an exponential decay pulse between the two arrays of conductive microprojections to create a non-uniform electrical field and electrokinetically driving the therapeutic agent through the stratum corneum layer of skin.

Bi-directional flow induced by an AC electroosmotic micropump with DC voltage bias.

PubMed

Islam, Nazmul; Reyna, Jairo

2012-04-01

This paper discusses the principle of biased alternating current electroosmosis (ACEO) and its application to move the bulk fluid in a microchannel, as an alternative to mechanical pumping methods. Previous EO-driven flow research has looked at the effect of electrode asymmetry and transverse traveling wave forms on the performance of electroosmotic pumps. This paper presents an analysis that was conducted to assess the effect of combining an AC signal with a DC (direct current) bias when generating the electric field needed to impart electroosmosis (EO) within a microchannel. The results presented here are numerical and experimental. The numerical results were generated through simulations performed using COMSOL 3.5a. Currently available theoretical models for EO flows were embedded in the software and solved numerically to evaluate the effects of channel geometry, frequency of excitation, electrode array geometry, and AC signal with a DC bias on the flow imparted on an electrically conducting fluid. Simulations of the ACEO flow driven by a constant magnitude of AC voltage over symmetric electrodes did not indicate relevant net flows. However, superimposing a DC signal over the AC signal on the same symmetric electrode array leads to a noticeable net forward flow. Moreover, changing the polarity of electrical signal creates a bi-directional flow on symmetrical electrode array. Experimental flow measurements were performed on several electrode array configurations. The mismatch between the numerical and experimental results revealed the limitations of the currently available models for the biased EO. However, they confirm that using a symmetric electrode array excited by an AC signal with a DC bias leads to a significant improvement in flow rates in comparison to the flow rates obtained in an asymmetric electrode array configuration excited just with an AC signal. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Human motor cortical activity recorded with Micro-ECoG electrodes, during individual finger movements.

PubMed

Wang, W; Degenhart, A D; Collinger, J L; Vinjamuri, R; Sudre, G P; Adelson, P D; Holder, D L; Leuthardt, E C; Moran, D W; Boninger, M L; Schwartz, A B; Crammond, D J; Tyler-Kabara, E C; Weber, D J

2009-01-01

In this study human motor cortical activity was recorded with a customized micro-ECoG grid during individual finger movements. The quality of the recorded neural signals was characterized in the frequency domain from three different perspectives: (1) coherence between neural signals recorded from different electrodes, (2) modulation of neural signals by finger movement, and (3) accuracy of finger movement decoding. It was found that, for the high frequency band (60-120 Hz), coherence between neighboring micro-ECoG electrodes was 0.3. In addition, the high frequency band showed significant modulation by finger movement both temporally and spatially, and a classification accuracy of 73% (chance level: 20%) was achieved for individual finger movement using neural signals recorded from the micro-ECoG grid. These results suggest that the micro-ECoG grid presented here offers sufficient spatial and temporal resolution for the development of minimally-invasive brain-computer interface applications.

An improved biosensor for acetaldehyde determination using a bienzymatic strategy at poly(neutral red) modified carbon film electrodes.

PubMed

Ghica, Mariana Emilia; Pauliukaite, Rasa; Marchand, Nicolas; Devic, Eric; Brett, Christopher M A

2007-05-15

Improved biosensors for acetaldehyde determination have been developed using a bienzymatic strategy, based on a mediator-modified carbon film electrode and co-immobilisation of NADH oxidase and aldehyde dehydrogenase. Modification of the carbon film electrode with poly(neutral red) mediator resulted in a sensitive, low-cost and reliable NADH detector. Immobilisation of the enzymes was performed using encapsulation in a sol-gel matrix or cross-linking with glutaraldehyde. The bienzymatic biosensors were characterized by studying the influence of pH, applied potential and co-factors. The sol-gel and glutaraldehyde biosensors showed a linear response up to 60 microM and 100 microM, respectively, with detection limits of 2.6 microM and 3.3 microM and sensitivities were 1.7 microA mM(-1) and 5.6 microA mM(-1). The optimised biosensors showed good stability and good selectivity and have been tested for application for the determination of acetaldehyde in natural samples such as wine.

Chronic intracortical microstimulation (ICMS) of cat sensory cortex using the Utah Intracortical Electrode Array.

PubMed

Rousche, P J; Normann, R A

1999-03-01

In an effort to assess the safety and efficacy of focal intracortical microstimulation (ICMS) of cerebral cortex with an array of penetrating electrodes as might be applied to a neuroprosthetic device to aid the deaf or blind, we have chronically implanted three trained cats in primary auditory cortex with the 100-electrode Utah Intracortical Electrode Array (UIEA). Eleven of the 100 electrodes were hard-wired to a percutaneous connector for chronic access. Prior to implant, cats were trained to "lever-press" in response to pure tone auditory stimulation. After implant, this behavior was transferred to "lever-presses" in response to current injections via single electrodes of the implanted arrays. Psychometric function curves relating injected charge level to the probability of response were obtained for stimulation of 22 separate electrodes in the three implanted cats. The average threshold charge/phase required for electrical stimulus detection in each cat was, 8.5, 8.6, and 11.6 nC/phase respectively, with a maximum charge/phase of 26 nC/phase and a minimum of 1.5 nC/phase thresholds were tracked for varying time intervals, and seven electrodes from two cats were tracked for up to 100 days. Electrodes were stimulated for no more than a few minutes each day. Neural recordings taken from the same electrodes before and after multiple electrical stimulation sessions were very similar in signal/noise ratio and in the number of recordable units, suggesting that the range of electrical stimulation levels used did not damage neurons in the vicinity of the electrodes. Although a few early implants failed, we conclude that ICMS of cerebral cortex to evoke a behavioral response can be achieved with the penetrating UIEA. Further experiments in support of a sensory cortical prosthesis based on ICMS are warranted.

Efficiency enhancement of silicon nanowire solar cells by using UV/Ozone treatments and micro-grid electrodes

NASA Astrophysics Data System (ADS)

Chen, Junyi; Subramani, Thiyagu; Sun, Yonglie; Jevasuwan, Wipakorn; Fukata, Naoki

2018-05-01

Silicon nanowire solar cells were fabricated by metal catalyzed electroless etching (MCEE) followed by thermal chemical vapor deposition (CVD). In this study, we investigated two effects, a UV/ozone treatment and the use of a micro-grid electrodes, to enhance light absorption and reduce the optic losses in the solar cell device. The UV/ozone treatment successfully improved the conversion efficiency. The micro-grid electrodes were then applied in solar cell devices subjected to a back surface field (BSF) treatment and rapid thermal annealing (RTA). These effects improved the conversion efficiency from 9.4% to 10.9%. Moreover, to reduce surface recombination and improve the continuity of front electrodes, we optimized the etching time of the MCEE process, giving a high efficiency of 12.3%.

In situ fabrication of Ni-Co (oxy)hydroxide nanowire-supported nanoflake arrays and their application in supercapacitors.

PubMed

Zheng, Xiaoyu; Quan, Honglin; Li, Xiaoxin; He, Hai; Ye, Qinglan; Xu, Xuetang; Wang, Fan

2016-09-29

Three-dimensional (3D) hybrid nanostructured arrays grown on a flexible substrate have recently attracted great attention owing to their potential application as supercapacitor electrodes in portable and wearable electronic devices. Here, we report an in situ conversion of Ni-Co active electrode materials for the fabrication of high-performance electrodes. Ni-Co carbonate hydroxide nanowire arrays on carbon cloth were initially synthesized via a hydrothermal method, and they were gradually converted to Ni-Co (oxy)hydroxide nanowire-supported nanoflake arrays after soaking in an alkaline solution. The evolution of the supercapacitor performance of the soaked electrode was investigated in detail. The areal capacitance increases from 281 mF cm -2 at 1 mA cm -2 to 3710 and 3900 mF cm -2 after soaking for 36 h and 48 h, respectively. More interestingly, the electrode also shows an increased capacitance with charge/discharge cycles due to the long-time soaking in KOH solution, suggesting novel cycling durability. The enhancement in capacitive performance should be related to the formation of a unique nanowire-supported nanoflake array architecture, which controls the agglomeration of nanoflakes, making them fully activated. As a result, the facile in situ fabrication of the hybrid architectural design in this study provides a new approach to fabricate high-performance Ni/Co based hydroxide nanostructure arrays for next-generation energy storage devices.

Three-dimensional electrodes for dye-sensitized solar cells: synthesis of indium-tin-oxide nanowire arrays and ITO/TiO2 core-shell nanowire arrays by electrophoretic deposition

NASA Astrophysics Data System (ADS)

Wang, Hong-Wen; Ting, Chi-Feng; Hung, Miao-Ken; Chiou, Chwei-Huann; Liu, Ying-Ling; Liu, Zongwen; Ratinac, Kyle R.; Ringer, Simon P.

2009-02-01

Dye-sensitized solar cells (DSSCs) show promise as a cheaper alternative to silicon-based photovoltaics for specialized applications, provided conversion efficiency can be maximized and production costs minimized. This study demonstrates that arrays of nanowires can be formed by wet-chemical methods for use as three-dimensional (3D) electrodes in DSSCs, thereby improving photoelectric conversion efficiency. Two approaches were employed to create the arrays of ITO (indium-tin-oxide) nanowires or arrays of ITO/TiO2 core-shell nanowires; both methods were based on electrophoretic deposition (EPD) within a polycarbonate template. The 3D electrodes for solar cells were constructed by using a doctor-blade for coating TiO2 layers onto the ITO or ITO/TiO2 nanowire arrays. A photoelectric conversion efficiency as high as 4.3% was achieved in the DSSCs made from ITO nanowires; this performance was better than that of ITO/TiO2 core-shell nanowires or pristine TiO2 films. Cyclic voltammetry confirmed that the reaction current was significantly enhanced when a 3D ITO-nanowire electrode was used. Better separation of charge carriers and improved charge transport, due to the enlarged interfacial area, are thought to be the major advantages of using 3D nanowire electrodes for the optimization of DSSCs.

Micro-reaction chamber electrodes for neural stimulation and recording.

PubMed

Shanmugasundaram, Balaji; Gluckman, Bruce J

2011-01-01

Biocompatible electrodes with smaller geometric area are preferred to improve the selectivity of the neural recording and stimulation applications. We introduce the concept of a micro-reaction chamber (μRC) in which a volume within the electrode back plane is used to confine and sequester the electrochemical reactions used for charge passage. The URC electrode design helps decrease impedance and improves the charge storage capacity without altering the geometry of the active site. Here we demonstrate that μRC electrodes fabricated from 50 μm diameter microwire have significantly improved charge storage capacity and lowered impedance at physiologically relevant frequencies in phosphate buffered saline solution compared with other designs.

Microsystems Technology for Retinal Implants

NASA Astrophysics Data System (ADS)

Weiland, James

2005-03-01

The retinal prosthesis is targeted to treat age-related macular degeneration, retinitis pigmentosa, and other outer retinal degenerations. Simulations of artificial vision have predicted that 600-1000 individual pixels will be needed if a retinal prosthesis is to restore function such as reading large print and face recognition. An implantable device with this many electrode contacts will require microsystems technology as part of its design. An implantable retinal prosthesis will consist of several subsystems including an electrode array and hermetic packaging. Microsystems and microtechnology approaches are being investigated as possible solutions for these design problems. Flexible polydimethylsiloxane (PDMS) substrate electrode arrays and silicon micromachined electrode arrays are under development. Inactive PDMS electrodes have been implanted in 3 dogs to assess mechanical biocompatibility. 3 dogs were followed for 6 months. The implanted was securely fastened to the retina with a single retinal tack. No post-operative complications were evident. The array remained within 100 microns of the retinal surface. Histological evaluation showed a well preserved retina underneath the electrode array. A silicon device with electrodes suspended on micromachined springs has been implanted in 4 dogs (2 acute implants, 2 chronic implants). The device, though large, could be inserted into the eye and positioned on the retina. Histological analysis of the retina from the spring electrode implants showed that spring mounted posts penetrated the retina, thus the device will be redesigned to reduce the strength of the springs. These initial implants will provide information for the designers to make the next generation silicon device. We conclude that microsystems technology has the potential to make possible a retinal prosthesis with 1000 individual contacts in close proximity to the retina.

Engineering challenges of BioNEMS: the integration of microfluidics, micro- and nanodevices, models and external control for systems biology.

PubMed

Wikswo, J P; Prokop, A; Baudenbacher, F; Cliffel, D; Csukas, B; Velkovsky, M

2006-08-01

Systems biology, i.e. quantitative, postgenomic, postproteomic, dynamic, multiscale physiology, addresses in an integrative, quantitative manner the shockwave of genetic and proteomic information using computer models that may eventually have 10(6) dynamic variables with non-linear interactions. Historically, single biological measurements are made over minutes, suggesting the challenge of specifying 10(6) model parameters. Except for fluorescence and micro-electrode recordings, most cellular measurements have inadequate bandwidth to discern the time course of critical intracellular biochemical events. Micro-array expression profiles of thousands of genes cannot determine quantitative dynamic cellular signalling and metabolic variables. Major gaps must be bridged between the computational vision and experimental reality. The analysis of cellular signalling dynamics and control requires, first, micro- and nano-instruments that measure simultaneously multiple extracellular and intracellular variables with sufficient bandwidth; secondly, the ability to open existing internal control and signalling loops; thirdly, external BioMEMS micro-actuators that provide high bandwidth feedback and externally addressable intracellular nano-actuators; and, fourthly, real-time, closed-loop, single-cell control algorithms. The unravelling of the nested and coupled nature of cellular control loops requires simultaneous recording of multiple single-cell signatures. Externally controlled nano-actuators, needed to effect changes in the biochemical, mechanical and electrical environment both outside and inside the cell, will provide a major impetus for nanoscience.

Recent advancements in nanoelectrodes and nanopipettes used in combined scanning electrochemical microscopy techniques.

PubMed

Kranz, Christine

2014-01-21

In recent years, major developments in scanning electrochemical microscopy (SECM) have significantly broadened the application range of this electroanalytical technique from high-resolution electrochemical imaging via nanoscale probes to large scale mapping using arrays of microelectrodes. A major driving force in advancing the SECM methodology is based on developing more sophisticated probes beyond conventional micro-disc electrodes usually based on noble metals or carbon microwires. This critical review focuses on the design and development of advanced electrochemical probes particularly enabling combinations of SECM with other analytical measurement techniques to provide information beyond exclusively measuring electrochemical sample properties. Consequently, this critical review will focus on recent progress and new developments towards multifunctional imaging.

Coated carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

2006-12-12

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Coated carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA

2008-10-28

The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

Electrochemical cell method

DOEpatents

Kaun, T.D.; Eshman, P.F.

1980-05-09

A secondary electrochemical cell is prepared by providing positive and negative electrodes having outer enclosures of rigid perforated electrically conductive material defining an internal compartment containing the electrode material in porous solid form. The electrodes are each immersed in molten electrolyte salt prior to cell assembly to incorporate the cell electrolyte. Following solidification of the electrolyte substantially throughout the porous volume of the electrode material, the electrodes are arranged in an alternating positive-negative array with interelectrode separators of porous frangible electrically insulative material. The completed array is assembled into the cell housing and sealed such that on heating the solidified electrolyte flows into the interelectrode separator.

Micro-Ring Structures Stabilize Microdroplets to Enable Long Term Spheroid Culture in 384 Hanging Drop Array Plates

PubMed Central

Hsiao, Amy Y.; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J.; Takayama, Shuichi

2012-01-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis. PMID:22057945

Micro-ring structures stabilize microdroplets to enable long term spheroid culture in 384 hanging drop array plates.

PubMed

Hsiao, Amy Y; Tung, Yi-Chung; Kuo, Chuan-Hsien; Mosadegh, Bobak; Bedenis, Rachel; Pienta, Kenneth J; Takayama, Shuichi

2012-04-01

Using stereolithography, 20 different structural variations comprised of millimeter diameter holes surrounded by trenches, plateaus, or micro-ring structures were prepared and tested for their ability to stably hold arrays of microliter sized droplets within the structures over an extended period of time. The micro-ring structures were the most effective in stabilizing droplets against mechanical and chemical perturbations. After confirming the importance of micro-ring structures using rapid prototyping, we developed an injection molding tool for mass production of polystyrene 3D cell culture plates with an array of 384 such micro-ring surrounded through-hole structures. These newly designed and injection molded polystyrene 384 hanging drop array plates with micro-rings were stable and robust against mechanical perturbations as well as surface fouling-facilitated droplet spreading making them capable of long term cell spheroid culture of up to 22 days within the droplet array. This is a significant improvement over previously reported 384 hanging drop array plates which are susceptible to small mechanical shocks and could not reliably maintain hanging drops for longer than a few days. With enhanced droplet stability, the hanging drop array plates with micro-ring structures provide better platforms and open up new opportunities for high-throughput preparation of microscale 3D cell constructs for drug screening and cell analysis.

Mechanical, Biological and Electrochemical Investigations of Advanced Micro/Nano Materials for Tissue Engineering and Energy Storage

NASA Astrophysics Data System (ADS)

Pu, Juan

Various micro/nano materials have been extensively studied for applications in tissue engineering and energy storage. Tissue engineering seeks to repair or replace damaged tissue by integrating approaches from cellular/molecular biology and material chemistry/engineering. A major challenge is the consistent design of three-dimensional (3D) scaffolds that mimic the structure and biological functions of extracellular matrix (ECM), guide cell migration, provide mechanical support, and regulate cell activity. Electrospun micro/nanofibers have been investigated as promising tissue engineering scaffolds because they resemble native ECM and possess tunable surface morphologies. Supercapacitors, one of the energy storage devices, bridge the performance gap between rechargeable batteries and conventional capacitors. Active electrode materials of supercapacitors must possess high specific surface area, high conductivity, and good electrochemical properties. Carbon-based micro/nano-particles, such as graphene, activated carbon (AC), and carbon nanotubes, are commonly used as active electrode materials for storing charge in supercapacitors by the electrical double layer mechanism due to their high specific surface area and excellent conductivity. In this thesis, the mechanical properties of electrospun bilayer microfibrous membranes were investigated for potential applications in tissue engineering. Bilayer microfibrous membranes of poly(l-lactic acid) (PLLA) were fabricated by electrospinning using a parallel-disk mandrel configuration, which resulted in the sequential deposition of a layer with aligned fibers (AFL) across the two parallel disks and a layer with random fibers (RFL), both deposited by a single process step. The membrane structure and fiber alignment were characterized by scanning electron microscopy and two-dimensional fast Fourier transform. Because of the intricacies of the generated electric field, the bilayer membranes exhibited higher porosity than the membranes fabricated with a single drum collector. Furthermore, the bilayer PLLA scaffolds showed gradual variation in through-thickness porosity and fiber alignment and an average porosity much higher than that of conventionally electrospun scaffolds (controls) with randomly distributed fibers. The biocompatibility and biological performance of the bilayer fibrous scaffolds was evaluated by in vivo experiments involving subcutaneous scaffold implantation in Sprague-Dawley rats, followed by histology and immunohistochemistry studies. The results illustrate the potential of bilayer scaffolds to overcome major limitations of conventionally electrospun scaffolds associated with intrinsically small pores, low porosity and, consequently, poor cell infiltration. The significantly higher porosity and larger pore size of the RFL enhanced cell motility through the scaffold thickness, whereas the relatively dense structure of the AFL provided adequate mechanical strength. The bilayer scaffolds showed more than two times higher cell infiltration than controls during implantation in vivo. Moreover, the unique structure of bilayer scaffolds promoted collagen fiber deposition, cell proliferation, and ingrowth of smooth muscle cells and endothelial cells in vivo.. Novel all-solid-state microsupercapacitors (MSCs) with 3D electrodes consisting of active materials and a polymer electrolyte (PE) designed for high-energy-density storage applications were fabricated and tested. The incorporation of a PE in the electrode material enhanced the accessibility of the surface of active materials by electrolyte ions and decreased the ion diffusion path during electrochemical charging/discharging. For a scan rate of 5 mV s -1, the MSCs with graphene/PE and AC/PE composite electrodes demonstrated a very high areal capacitance of 95 and 134 mF cm-2 , respectively, comparable with that of 3D MSCs having a liquid electrolyte. In addition, the graphene/PE MSCs showed 70% increase in specific capacitance after 10,000 charge/discharge cycles, attributed to an electro-activation process resulting from ion intercalation between the graphene nanosheets. The AC/PE MSCs also demonstrated excellent stability. Single-walled carbon nanotube (SWCNT) networks were deposited on an ultrathin polyimide substrate using the spray-deposition technique and patterned into interdigital electrodes to construct ultrahigh-power, extremely flexible, and foldable MSCs capable of operating at an ultrahigh scan rate and delivering a stack capacitance of 18 F cm-3 and an energy density of 1.6 mWh cm-3, which is comparable with that of lithium thin-film batteries. An ultrahigh power density of 1125 W cm-3 and extremely small time constant of 1 ms were obtained with SWCNT MSCs, comparable with aluminum electrolytic capacitors. A honeycomb polydimethylsiloxane substrate was introduced for stretchable MSC arrays based on SWNCT interdigital electrodes, which enables facile integration in flexible or wearable electronics. The honeycomb structure accommodates large deformation without generating large strains in the MSCs and interconnects. The results show that such stretchable MSC arrays with SWCNT electrodes demonstrate excellent rate capability and power performance as well as electrochemical stability up to 150% or 275% stretching and under excessive bending or twisting. The present stretchable MSC arrays with honeycomb structures show high potential for integration with other electronics, such as energy harvesters, power management circuits, wireless charging circuits, and various sensors, encompassing a wide range of wearable, bio-implantable electronic systems. (Abstract shortened by ProQuest.).

Fully integrated micro-separator with soft-magnetic micro-pillar arrays for filtrating lymphocytes.

PubMed

Dong, Tao; Su, Qianhua; Yang, Zhaochu; Karlsen, Frank; Jakobsen, Henrik; Egeland, Eirik Bentzen; Hjelseth, Snorre

2010-01-01

A fully integrated micro-separator with soft-magnetic micro-pillar arrays has been developed, which merely employs one independent Lab-On-Chip to realize the lymphocytes isolation from the human whole blood. The simulation, fabrication and experiment are executed to realize this novel microseparator. The simulation results show that, the soft-magnetic micro-pillars array can amplify and redistribute the electromagnetic field generated by the microcoils. The tests certify desirable separation efficiency can be realized using this new separator at low current. No extra cooling system is required for such a micro-separator. This micro-separator can also be used to separate other target cells or particles with the same principle.

Programmable Aperture with MEMS Microshutter Arrays

NASA Technical Reports Server (NTRS)

Moseley, Samuel; Li, Mary; Kutyrev, Alexander; Kletetschka, Gunther; Fettig, Rainer

2011-01-01

A microshutter array (MSA) has been developed for use as an aperture array for multi-object selections in James Webb Space Telescope (JWST) technology. Light shields, molybdenum nitride (MoN) coating on shutters, and aluminum/aluminum oxide coatings on interior walls are put on each shutter for light leak prevention, and to enhance optical contrast. Individual shutters are patterned with a torsion flexure that permits shutters to open 90 deg. with a minimized mechanical stress concentration. The shutters are actuated magnetically, latched, and addressed electrostatically. Also, micromechanical features are tailored onto individual shutters to prevent stiction. An individual shutter consists of a torsion hinge, a shutter blade, a front electrode that is coated on the shutter blade, a backside electrode that is coated on the interior walls, and a magnetic cobalt-iron coating. The magnetic coating is patterned into stripes on microshutters so that shutters can respond to an external magnetic field for the magnetic actuation. A set of column electrodes is placed on top of shutters, and a set of row electrodes on sidewalls is underneath the shutters so that they can be electrostatically latched open. A linear permanent magnet is aligned with the shutter rows and is positioned above a flipped upside-down array, and sweeps across the array in a direction parallel to shutter columns. As the magnet sweeps across the array, sequential rows of shutters are rotated from their natural horizontal orientation to a vertical open position, where they approach vertical electrodes on the sidewalls. When the electrodes are biased with a sufficient electrostatic force to overcome the mechanical restoring force of torsion bars, shutters remain latched to vertical electrodes in their open state. When the bias is removed, or is insufficient, the shutters return to their horizontal, closed positions. To release a shutter, both the electrode on the shutter and the one on the back wall where the shutter sits are grounded. The shutters with one or both ungrounded electrodes are held open. Sub-micron bumps underneath light shields and silicon ribs on back walls are the two features to prevent stiction. These features ensure that the microshutter array functions properly in mechanical motions. The MSA technology can be used primarily in multi-object imaging and spectroscopy, photomask generation, light switches, and in the stepper equipment used to make integrated circuits and MEMS (microelectromechanical systems) devices.

Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors

NASA Astrophysics Data System (ADS)

Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

2011-05-01

Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g-1 at 1 A g-1, which remained at 543 F g-1 when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg-1) was maintained even at a high power density of 6000 W kg-1. An excellent long cycle life of the electrode was observed with a retention of ~86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO2 nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications.

Synthesis of NiMn-LDH Nanosheet@Ni3S2 Nanorod Hybrid Structures for Supercapacitor Electrode Materials with Ultrahigh Specific Capacitance.

PubMed

Yu, Shuai; Zhang, Yingxi; Lou, Gaobo; Wu, Yatao; Zhu, Xinqiang; Chen, Hao; Shen, Zhehong; Fu, Shenyuan; Bao, Binfu; Wu, Limin

2018-03-27

One of the key challenges for pseudocapacitive electrode materials with highly effective capacitance output and future practical applications is how to rationally construct hierarchical and ordered hybrid nanoarchitecture through the simple process. Herein, we design and synthesize a novel NiMn-layered double hydroxide nanosheet@Ni 3 S 2 nanorod hybrid array supported on porous nickel foam via a one-pot hydrothermal method. Benefited from the ultrathin and rough nature, the well-defined porous structure of the hybrid array, as well as the synergetic effect between NiMn-layered double hydroxide nanosheets and Ni 3 S 2 nanorods, the as-fabricated hybrid array-based electrode exhibits an ultrahigh specific capacitance of 2703 F g -1 at 3 A g -1 . Moreover, the asymmetric supercapacitor with this hybrid array as a positive electrode and wood-derived activated carbon as a negative electrode demonstrates high energy density (57 Wh Kg -1 at 738 W Kg -1 ) and very good electrochemical cycling stability.

Functionalization of indium-tin-oxide electrodes by laser-nanostructured gold thin films for biosensing applications

NASA Astrophysics Data System (ADS)

Grochowska, Katarzyna; Siuzdak, Katarzyna; Karczewski, Jakub; Śliwiński, Gerard

2015-12-01

The production and properties of the indium-tin-oxide (ITO) electrodes functionalized by Au nanoparticle (NP) arrays of a relatively large area formed by pulsed laser nanostructuring of thin gold films are reported and discussed. The SEM inspection of modified electrodes reveals the presence of the nearly spherical and disc-shaped particles of dimensions in the range of 40-120 nm. The NP-array geometry can be controlled by selection of the laser processing conditions. It is shown that particle size and packing density of the array are important factors which determine the electrode performance. In the case of NP-modified electrodes the peak current corresponding to the glucose direct oxidation process shows rise with increasing glucose concentration markedly higher comparing to the reference Au disc electrode. The detection limit reaches 12 μM and linear response of the sensor is observed from 0.1 to 47 mM that covers the normal physiological range of the blood sugar detection.

Electrochemical DNA biosensor based on the BDD nanograss array electrode.

PubMed

Jin, Huali; Wei, Min; Wang, Jinshui

2013-04-10

The development of DNA biosensor has attracted considerable attention due to their potential applications, including gene analysis, clinical diagnostics, forensic study and more medical applications. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry in this study. Electrochemical DNA biosensor was developed based on the BDD film electrode (fBDD) and BDD nanograss array electrode (nBDD). In comparison with fBDD and AuNPs/CA/fBDD electrode, the lower semicircle diameter of electrochemical impedance spectroscopy obtained on nBDD and AuNPs/CA/nBDD electrode indicated that the presence of nanograss array improved the reactive site, reduced the interfacial resistance, and made the electron transfer easier. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry. The experimental results demonstrated that the prepared AuNPs/CA/nBDD electrode was suitable for DNA hybridization with favorable performance of faster response, higher sensitivity, lower detection limit and satisfactory selectivity, reproducibility and stability.

Electrochemical DNA biosensor based on the BDD nanograss array electrode

PubMed Central

2013-01-01

Background The development of DNA biosensor has attracted considerable attention due to their potential applications, including gene analysis, clinical diagnostics, forensic study and more medical applications. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry in this study. Results Electrochemical DNA biosensor was developed based on the BDD film electrode (fBDD) and BDD nanograss array electrode (nBDD). In comparison with fBDD and AuNPs/CA/fBDD electrode, the lower semicircle diameter of electrochemical impedance spectroscopy obtained on nBDD and AuNPs/CA/nBDD electrode indicated that the presence of nanograss array improved the reactive site, reduced the interfacial resistance, and made the electron transfer easier. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry. Conclusions The experimental results demonstrated that the prepared AuNPs/CA/nBDD electrode was suitable for DNA hybridization with favorable performance of faster response, higher sensitivity, lower detection limit and satisfactory selectivity, reproducibility and stability. PMID:23575250

Fabrication of Flexible Microneedle Array Electrodes for Wearable Bio-Signal Recording.

PubMed

Ren, Lei; Xu, Shujia; Gao, Jie; Lin, Zi; Chen, Zhipeng; Liu, Bin; Liang, Liang; Jiang, Lelun

2018-04-13

Laser-direct writing (LDW) and magneto-rheological drawing lithography (MRDL) have been proposed for the fabrication of a flexible microneedle array electrode (MAE) for wearable bio-signal monitoring. Conductive patterns were directly written onto the flexible polyethylene terephthalate (PET) substrate by LDW. The microneedle array was rapidly drawn and formed from the droplets of curable magnetorheological fluid with the assistance of an external magnetic field by MRDL. A flexible MAE can maintain a stable contact interface with curved human skin due to the flexibility of the PET substrate. Compared with Ag/AgCl electrodes and flexible dry electrodes (FDE), the electrode-skin interface impedance of flexible MAE was the minimum even after a 50-cycle bending test. Flexible MAE can record electromyography (EMG), electroencephalography (EEG) and static electrocardiography (ECG) signals with good fidelity. The main features of the dynamic ECG signal recorded by flexible MAE are the most distinguishable with the least moving artifacts. Flexible MAE is an attractive candidate electrode for wearable bio-signal monitoring.

High energy density micro-fiber based nickel electrode for aerospace batteries

NASA Technical Reports Server (NTRS)

Francisco, Jennifer; Chiappetti, Dennis; Coates, Dwaine

1996-01-01

The nickel electrode is the specific energy limiting component in battery systems such as nickel-hydrogen, nickel-metal hydride and nickel-zinc. Lightweight, high energy density nickel electrodes have been developed which deliver in excess of 180 mAh/g at the one-hour discharge rate. These electrodes are based on a highly porous, nickel micro-fiber (less than 10 micron diameter) substrate, electrochemically impregnated with nickel-hydroxide active material. Electrodes are being tested both as a flooded half-cell and in full nickel-hydrogen and nickel-metal hydride cells. The electrode technology developed is applicable to commercial nickel-based batteries for applications such as electric vehicles, cellular telephones and laptop computers and for low-cost, high energy density military and aerospace applications.

Visualizing transplanted muscle flaps using minimally invasive multi-electrode bioimpedance spectroscopy

NASA Astrophysics Data System (ADS)

Gordon, R.; Zorkova, V.; Min, M.; Rätsep, I.

2010-04-01

We describe here an imaging system that uses bioimpedance spectroscopy with multi-electrode array to indicate the state of muscle flap regions under the array. The system is able to differentiate between different health states in the tissue and give early information about the location and size of ischemic sub-regions. The array will be 4*8 electrodes with the spacing of 5mm between the electrodes (the number of electrodes and the spacing may vary). The electrodes are minimally invasive short stainless steel needles, that penetrate 0.3 mm into the tissue with the goal of achieving a wet electric contact. We combine 32 configurations of 4-electrode multi-frequency impedance measurements to derive a health-state map for the transplanted flap. The imaging method is tested on a model consisting of 2 tissues and FEM software (Finite Element Method -COMSOL Multiphysics based) is used to conduct the measurements virtually. Dedicated multichannel bioimpedance measurement equipment has already been developed and tested, that cover the frequency range from 100 Hz to 1 MHz.

Gynecologic electrical impedance tomograph

NASA Astrophysics Data System (ADS)

Korjenevsky, A.; Cherepenin, V.; Trokhanova, O.; Tuykin, T.

2010-04-01

Electrical impedance tomography extends to the new and new areas of the medical diagnostics: lungs, breast, prostate, etc. The feedback from the doctors who use our breast EIT diagnostic system has induced us to develop the 3D electrical impedance imaging device for diagnostics of the cervix of the uterus - gynecologic impedance tomograph (GIT). The device uses the same measuring approach as the breast imaging system: 2D flat array of the electrodes arranged on the probe with handle is placed against the body. Each of the 32 electrodes of the array is connected in turn to the current source while the rest electrodes acquire the potentials on the surface. The current flows through the electrode of the array and returns through the remote electrode placed on the patient's limb. The voltages are measured relative to another remote electrode. The 3D backprojection along equipotential surfaces is used to reconstruct conductivity distribution up to approximately 1 cm in depth. Small number of electrodes enables us to implement real time imaging with a few frames per sec. rate. The device is under initial testing and evaluation of the imaging capabilities and suitability of usage.

An electrocorticographic electrode array for simultaneous recording from medial, lateral, and intrasulcal surface of the cortex in macaque monkeys.

PubMed

Fukushima, Makoto; Saunders, Richard C; Mullarkey, Matthew; Doyle, Alexandra M; Mishkin, Mortimer; Fujii, Naotaka

2014-08-15

Electrocorticography (ECoG) permits recording electrical field potentials with high spatiotemporal resolution over a large part of the cerebral cortex. Application of chronically implanted ECoG arrays in animal models provides an opportunity to investigate global spatiotemporal neural patterns and functional connectivity systematically under various experimental conditions. Although ECoG is conventionally used to cover the gyral cortical surface, recent studies have shown the feasibility of intrasulcal ECoG recordings in macaque monkeys. Here we developed a new ECoG array to record neural activity simultaneously from much of the medial and lateral cortical surface of a single hemisphere, together with the supratemporal plane (STP) of the lateral sulcus in macaque monkeys. The ECoG array consisted of 256 electrodes for bipolar recording at 128 sites. We successfully implanted the ECoG array in the left hemisphere of three rhesus monkeys. The electrodes in the auditory and visual cortex detected robust event related potentials to auditory and visual stimuli, respectively. Bipolar recording from adjacent electrode pairs effectively eliminated chewing artifacts evident in monopolar recording, demonstrating the advantage of using the ECoG array under conditions that generate significant movement artifacts. Compared with bipolar ECoG arrays previously developed for macaque monkeys, this array significantly expands the number of cortical target areas in gyral and intralsulcal cortex. This new ECoG array provides an opportunity to investigate global network interactions among gyral and intrasulcal cortical areas. Published by Elsevier B.V.

Stacked 3D RRAM Array with Graphene/CNT as Edge Electrodes

PubMed Central

Bai, Yue; Wu, Huaqiang; Wang, Kun; Wu, Riga; Song, Lin; Li, Tianyi; Wang, Jiangtao; Yu, Zhiping; Qian, He

2015-01-01

There are two critical challenges which determine the array density of 3D RRAM: 1) the scaling limit in both horizontal and vertical directions; 2) the integration of selector devices in 3D structure. In this work, we present a novel 3D RRAM structure using low-dimensional materials, including 2D graphene and 1D carbon nanotube (CNT), as the edge electrodes. A two-layer 3D RRAM with monolayer graphene as edge electrode is demonstrated. The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale. Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized. Furthermore, the discussion of high array density potential is presented. PMID:26348797

Stacked 3D RRAM Array with Graphene/CNT as Edge Electrodes.

PubMed

Bai, Yue; Wu, Huaqiang; Wang, Kun; Wu, Riga; Song, Lin; Li, Tianyi; Wang, Jiangtao; Yu, Zhiping; Qian, He

2015-09-08

There are two critical challenges which determine the array density of 3D RRAM: 1) the scaling limit in both horizontal and vertical directions; 2) the integration of selector devices in 3D structure. In this work, we present a novel 3D RRAM structure using low-dimensional materials, including 2D graphene and 1D carbon nanotube (CNT), as the edge electrodes. A two-layer 3D RRAM with monolayer graphene as edge electrode is demonstrated. The electrical results reveal that the RRAM devices could switch normally with this very thin edge electrode at nanometer scale. Meanwhile, benefited from the asymmetric carrier transport induced by Schottky barrier at metal/CNT and oxide/CNT interfaces, a selector built-in 3D RRAM structure using CNT as edge electrode is successfully fabricated and characterized. Furthermore, the discussion of high array density potential is presented.

In-Vivo Characterization of Glassy Carbon Micro-Electrode Arrays for Neural Applications and Histological Analysis of the Brain Tissue

NASA Astrophysics Data System (ADS)

Vomero, Maria

The aim of this work is to fabricate and characterize glassy carbon Microelectrode Arrays (MEAs) for sensing and stimulating neural activity, and conduct histological analysis of the brain tissue after the implant to determine long-term performance. Neural applications often require robust electrical and electrochemical response over a long period of time, and for those applications we propose to replace the commonly used noble metals like platinum, gold and iridium with glassy carbon. We submit that such material has the potential to improve the performances of traditional neural prostheses, thanks to better charge transfer capabilities and higher electrochemical stability. Great interest and attention is given in this work, in particular, to the investigation of tissue response after several weeks of implants in rodents' brain motor cortex and the associated materials degradation. As part of this work, a new set of devices for Electrocorticography (ECoG) has been designed and fabricated to improve durability and quality of the previous generation of devices, designed and manufactured by the same research group in 2014. In-vivo long-term impedance measurements and brain activity recordings were performed to test the functionality of the neural devices. In-vitro electrical characterization of the carbon electrodes, as well as the study of the adhesion mechanisms between glassy carbon and different substrates is also part of the research described in this book.

Nanoscale electrode arrays produced with microscale lithographic techniques for use in biomedical sensing applications.

PubMed

Terry, Jonathan G; Schmüser, Ilka; Underwood, Ian; Corrigan, Damion K; Freeman, Neville J; Bunting, Andrew S; Mount, Andrew R; Walton, Anthony J

2013-12-01

A novel technique for the production of nanoscale electrode arrays that uses standard microfabrication processes and micron-scale photolithography is reported here in detail. These microsquare nanoband edge electrode (MNEE) arrays have been fabricated with highly reproducible control of the key array dimensions, including the size and pitch of the individual elements and, most importantly, the width of the nanoband electrodes. The definition of lateral features to nanoscale dimensions typically requires expensive patterning techniques that are complex and low-throughput. However, the fabrication methodology used here relies on the fact that vertical dimensions (i.e. layer thicknesses) have long been manufacturable at the nanoscale using thin film deposition techniques that are well established in mainstream microelectronics. The authors report for the first time two aspects that highlight the particular suitability of these MNEE array systems for probe monolayer biosensing. The first is simulation, which shows the enhanced sensitivity to the redox reaction of the solution redox couple. The second is the enhancement of probe film functionalisation observed for the probe film model molecule, 6-mercapto-1-hexanol compared with microsquare electrodes. Such surface modification for specific probe layer biosensing and detection is of significance for a wide range of biomedical and other sensing and analytical applications.

Simultaneous mixing and pumping using asymmetric microelectrodes

NASA Astrophysics Data System (ADS)

Kim, Byoung Jae; Yoon, Sang Youl; Sung, Hyung Jin; Smith, Charles G.

2007-10-01

This study proposes ideas for simultaneous mixing and pumping using asymmetric microelectrode arrays. The driving force of the mixing and pumping was based on electroosmotic flows induced by alternating current (ac) electric fields on asymmetric microelectrodes. The key idea was to bend/incline the microelectrodes like diagonal/herringbone shapes. Four patterns of the asymmetric electrode arrays were considered depending on the shape of electrode arrays. For the diagonal shape, repeated and staggered patterns of the electrode arrays were studied. For the herringbone shape, diverging and converging patterns were examined. These microelectrode patterns forced fluid flows in the lateral direction leading to mixing and in the channel direction leading to pumping. Three-dimensional numerical simulations were carried out using the linear theories of ac electro-osmosis. The performances of the mixing and pumping were assessed in terms of the mixing efficiency and the pumping flow rate. The results indicated that the helical flow motions induced by the electrode arrays play a significant role in the mixing enhancement. The pumping performance was influenced by the slip velocity at the center region of the channel compared to that near the side walls.

Array-type NH.sub.3 sensor

DOEpatents

West, David Lawrence; Montgomery, Frederick Charles; Armstrong, Timothy R; Warmack, Robert J

2013-12-31

An array-type sensor that senses NH.sub.3 includes non-Nernstian sensing elements constructed from metal and/or metal-oxide electrodes on an O.sub.2 ion conducting substrate. In one example sensor, one electrode may be made of platinum, another electrode may be made of manganese (III) oxide (Mn.sub.2O.sub.3), and another electrode may be made of tungsten trioxide (WO.sub.3). Some sensing elements may further include an electrode made of La.sub.0.6Sr.sub.0.4Co.sub.0.2Fe.sub0.8O.sub.3 and another electrode made of LaCr.sub.0.95.Mg.sub.0.05O.sub.3.

Graphene Transparent Conductive Electrodes for Next- Generation Microshutter Arrays

NASA Technical Reports Server (NTRS)

Li, Mary; Sultana, Mahmooda; Hess, Larry

2012-01-01

Graphene is a single atomic layer of graphite. It is optically transparent and has high electron mobility, and thus has great potential to make transparent conductive electrodes. This invention contributes towards the development of graphene transparent conductive electrodes for next-generation microshutter arrays. The original design for the electrodes of the next generation of microshutters uses indium-tin-oxide (ITO) as the electrode material. ITO is widely used in NASA flight missions. The optical transparency of ITO is limited, and the material is brittle. Also, ITO has been getting more expensive in recent years. The objective of the invention is to develop a graphene transparent conductive electrode that will replace ITO. An exfoliation procedure was developed to make graphene out of graphite crystals. In addition, large areas of single-layer graphene were produced using low-pressure chemical vapor deposition (LPCVD) with high optical transparency. A special graphene transport procedure was developed for transferring graphene from copper substrates to arbitrary substrates. The concept is to grow large-size graphene sheets using the LPCVD system through chemical reaction, transfer the graphene film to a substrate, dope graphene to reduce the sheet resistance, and pattern the film to the dimension of the electrodes in the microshutter array. Graphene transparent conductive electrodes are expected to have a transparency of 97.7%. This covers the electromagnetic spectrum from UV to IR. In comparison, ITO electrodes currently used in microshutter arrays have 85% transparency in mid-IR, and suffer from dramatic transparency drop at a wavelength of near-IR or shorter. Thus, graphene also has potential application as transparent conductive electrodes for Schottky photodiodes in the UV region.

A new method to assess skin treatments for lowering the impedance and noise of individual gelled Ag-AgCl electrodes.

PubMed

Piervirgili, G; Petracca, F; Merletti, R

2014-10-01

A model-based new procedure for measuring the single electrode-gel-skin impedance (ZEGS) is presented. The method is suitable for monitoring the contact impedance of the electrodes of a large array with limited modifications of the hardware and without removing or disconnecting the array from the amplifier. The procedure is based on multiple measurements between electrode pairs and is particularly suitable for electrode arrays. It has been applied to study the effectiveness of three skin treatments, with respect to no treatment, for reducing the electrode-gel-skin impedance (ZEGS) and noise: (i) rubbing with alcohol; (ii) rubbing with abrasive conductive paste; (iii) stripping with adhesive tape. The complex impedances ZEGS of the individual electrodes were measured by applying this procedure to disposable commercial Ag-AgCl gelled electrode arrays (4  ×  1) with a 5 mm(2) contact area. The impedance unbalance ΔZ = ZEGS1 - ZEGS2 and the RMS noise (VRMS) were measured between pairs of electrodes. The tissue impedance ZT was also obtained, as a collateral result. Measurements were repeated at t0 = 0 min and at t30 = 30 min from the electrode application. Mixed linear models and linear regression analysis applied to ZEGS, ΔZ and noise VRMS for the skin treatment factor demonstrated (a) that skin rubbing with abrasive conductive paste is more effective in lowering ZEGS, ΔZ and VRMS (p < 0.01) than the other treatments or no treatment, and (b) a statistically significant decrement (p < 0.01), between t0 and t30, of magnitude and phase of ZEGS.Rubbing with abrasive conductive paste significantly decreased the noise VRMS with respect to other treatments or no treatment.

Optimization of pillar electrodes in subretinal prosthesis for enhanced proximity to target neurons

NASA Astrophysics Data System (ADS)

Flores, Thomas; Lei, Xin; Huang, Tiffany; Lorach, Henri; Dalal, Roopa; Galambos, Ludwig; Kamins, Theodore; Mathieson, Keith; Palanker, Daniel

2018-06-01

Objective. High-resolution prosthetic vision requires dense stimulating arrays with small electrodes. However, such miniaturization reduces electrode capacitance and penetration of electric field into tissue. We evaluate potential solutions to these problems with subretinal implants based on utilization of pillar electrodes. Approach. To study integration of three-dimensional (3D) implants with retinal tissue, we fabricated arrays with varying pillar diameter, pitch, and height, and implanted beneath the degenerate retina in rats (Royal College of Surgeons, RCS). Tissue integration was evaluated six weeks post-op using histology and whole-mount confocal fluorescence imaging. The electric field generated by various electrode configurations was calculated in COMSOL, and stimulation thresholds assessed using a model of network-mediated retinal response. Main results. Retinal tissue migrated into the space between pillars with no visible gliosis in 90% of implanted arrays. Pillars with 10 μm height reached the middle of the inner nuclear layer (INL), while 22 μm pillars reached the upper portion of the INL. Electroplated pillars with dome-shaped caps increase the active electrode surface area. Selective deposition of sputtered iridium oxide onto the cap ensures localization of the current injection to the pillar top, obviating the need to insulate the pillar sidewall. According to computational model, pillars having a cathodic return electrode above the INL and active anodic ring electrode at the surface of the implant would enable six times lower stimulation threshold, compared to planar arrays with circumferential return, but suffer from greater cross-talk between the neighboring pixels. Significance. 3D electrodes in subretinal prostheses help reduce electrode-tissue separation and decrease stimulation thresholds to enable smaller pixels, and thereby improve visual acuity of prosthetic vision.

Modeling Intracochlear Magnetic Stimulation: A Finite-Element Analysis.

PubMed

Mukesh, S; Blake, D T; McKinnon, B J; Bhatti, P T

2017-08-01

This study models induced electric fields, and their gradient, produced by pulsatile current stimulation of submillimeter inductors for cochlear implantation. Using finite-element analysis, the lower chamber of the cochlea, scala tympani, is modeled as a cylindrical structure filled with perilymph bounded by tissue, bone, and cochlear neural elements. Single inductors as well as an array of inductors are modeled. The coil strength (~100 nH) and excitation parameters (peak current of 1-5 A, voltages of 16-20 V) are based on a formative feasibility study conducted by our group. In that study, intracochlear micromagnetic stimulation achieved auditory activation as measured through the auditory brainstem response in a feline model. With respect to the finite element simulations, axial symmetry of the inductor geometry is exploited to improve computation time. It is verified that the inductor coil orientation greatly affects the strength of the induced electric field and thereby the ability to affect the transmembrane potential of nearby neural elements. Furthermore, upon comparing an array of micro-inductors with a typical multi-site electrode array, magnetically excited arrays retain greater focus in terms of the gradient of induced electric fields. Once combined with further in vivo analysis, this modeling study may enable further exploration of the mechanism of magnetically induced, and focused neural stimulation.

Intracellular and Extracellular Recording of Spontaneous Action Potentials in Mammalian Neurons and Cardiac Cells with 3D Plasmonic Nanoelectrodes.

PubMed

Dipalo, Michele; Amin, Hayder; Lovato, Laura; Moia, Fabio; Caprettini, Valeria; Messina, Gabriele C; Tantussi, Francesco; Berdondini, Luca; De Angelis, Francesco

2017-06-14

Three-dimensional vertical micro- and nanostructures can enhance the signal quality of multielectrode arrays and promise to become the prime methodology for the investigation of large networks of electrogenic cells. So far, access to the intracellular environment has been obtained via spontaneous poration, electroporation, or by surface functionalization of the micro/nanostructures; however, these methods still suffer from some limitations due to their intrinsic characteristics that limit their widespread use. Here, we demonstrate the ability to continuously record both extracellular and intracellular-like action potentials at each electrode site in spontaneously active mammalian neurons and HL-1 cardiac-derived cells via the combination of vertical nanoelectrodes with plasmonic optoporation. We demonstrate long-term and stable recordings with a very good signal-to-noise ratio. Additionally, plasmonic optoporation does not perturb the spontaneous electrical activity; it permits continuous recording even during the poration process and can regulate extracellular and intracellular contributions by means of partial cellular poration.

Droplet-based chemistry on a programmable micro-chip

PubMed Central

Schwartz, Jon A.; Vykoukal, Jody V.; Gascoyne, Peter R. C.

2009-01-01

We describe the manipulation of aqueous droplets in an immiscible, low-permittivity suspending medium. Such droplets may serve as carriers for not only air- and water-borne samples, contaminants, chemical reagents, viral and gene products, and cells, but also the reagents to process and characterise these samples. We present proofs-of-concept for droplet manipulation through dielectrophoresis by: (1) moving droplets on a two-dimensional array of electrodes, (2) achieving dielectrically-activated droplet injection, (3) fusing and reacting droplets, and (4) conducting a basic biological assay through a combination of these steps. A long-term goal of this research is to provide a platform fluidic processor technology that can form the core of versatile, automated, micro-scale devices to perform chemical and biological assays at or near the point of care, which will increase the availability of modern medicine to people who do not have ready access to modern medical institutions, and decrease the cost and delays associated with that lack of access. PMID:15007434

Switchable Polymer Based Thin Film Coils as a Power Module for Wireless Neural Interfaces.

PubMed

Kim, S; Zoschke, K; Klein, M; Black, D; Buschick, K; Toepper, M; Tathireddy, P; Harrison, R; Solzbacher, F

2007-05-01

Reliable chronic operation of implantable medical devices such as the Utah Electrode Array (UEA) for neural interface requires elimination of transcutaneous wire connections for signal processing, powering and communication of the device. A wireless power source that allows integration with the UEA is therefore necessary. While (rechargeable) micro batteries as well as biological micro fuel cells are yet far from meeting the power density and lifetime requirements of an implantable neural interface device, inductive coupling between two coils is a promising approach to power such a device with highly restricted dimensions. The power receiving coils presented in this paper were designed to maximize the inductance and quality factor of the coils and microfabricated using polymer based thin film technologies. A flexible configuration of stacked thin film coils allows parallel and serial switching, thereby allowing to tune the coil's resonance frequency. The electrical properties of the fabricated coils were characterized and their power transmission performance was investigated in laboratory condition.

In vitro modifications of the scala tympani environment and the cochlear implant array surface.

PubMed

Kontorinis, Georgios; Scheper, Verena; Wissel, Kirsten; Stöver, Timo; Lenarz, Thomas; Paasche, Gerrit

2012-09-01

To investigate the influence of alterations of the scala tympani environment and modifications of the surface of cochlear implant electrode arrays on insertion forces in vitro. Research experimental study. Fibroblasts producing neurotrophic factors were cultivated on the surface of Nucleus 24 Contour Advance electrodes. Forces were recorded by an Instron 5542 Force Measurement System as three modified arrays were inserted into an artificial scala tympani model filled with phosphate-buffered saline (PBS). The recorded forces were compared to control groups including three unmodified electrodes inserted into a model filled with PBS (unmodified environment) or Healon (current practice). Fluorescence microscopy was used before and after the insertions to identify any remaining fibroblasts. Additionally, three Contour Advance electrodes were inserted into an artificial model, filled with alginate/barium chloride solution at different concentrations, while insertion forces were recorded. Modification of the scala tympani environment with 50% to 75% alginate gel resulted in a significant decrease in the insertion forces. The fibroblast-coated arrays also led to decreased forces comparable to those recorded with Healon. Fluorescence microscopy revealed fully cell-covered arrays before and partially covered arrays after the insertion; the fibroblasts on the arrays' modiolar surface remained intact. Modifications of the scala tympani's environment with 50% to 75% alginate/barium chloride and of the cochlear implant electrode surface with neurotrophic factor-producing fibroblasts drastically reduce the insertion forces. As both modifications may serve future intracochlear therapies, it is expected that these might additionally reduce possible insertion trauma. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

Ready fabrication of thin-film electrodes from building nanocrystals for micro-supercapacitors.

PubMed

Chen, Zheng; Weng, Ding; Wang, Xiaolei; Cheng, Yanhua; Wang, Ge; Lu, Yunfeng

2012-04-18

Thin-film pseudocapacitor electrodes with ultrafast lithium storage kinetics, high capacitance and excellent cycling stability were fabricated from monodispersed TiO(2) building nanocrystals, providing a novel approach towards next-generation micro-supercapacitor applications. This journal is © The Royal Society of Chemistry 2012

Behavioral and cellular consequences of high-electrode count Utah Arrays chronically implanted in rat sciatic nerve.

PubMed

Wark, H A C; Mathews, K S; Normann, R A; Fernandez, E

2014-08-01

Before peripheral nerve electrodes can be used for the restoration of sensory and motor functions in patients with neurological disorders, the behavioral and histological consequences of these devices must be investigated. These indices of biocompatibility can be defined in terms of desired functional outcomes; for example, a device may be considered for use as a therapeutic intervention if the implanted subject retains functional neurons post-implantation even in the presence of a foreign body response. The consequences of an indwelling device may remain localized to cellular responses at the device-tissue interface, such as fibrotic encapsulation of the device, or they may affect the animal more globally, such as impacting behavioral or sensorimotor functions. The objective of this study was to investigate the overall consequences of implantation of high-electrode count intrafascicular peripheral nerve arrays, High Density Utah Slanted Electrode Arrays (HD-USEAs; 25 electrodes mm(-2)). HD-USEAs were implanted in rat sciatic nerves for one and two month periods. We monitored wheel running, noxious sensory paw withdrawal reflexes, footprints, nerve morphology and macrophage presence at the tissue-device interface. In addition, we used a novel approach to contain the arrays in actively behaving animals that consisted of an organic nerve wrap. A total of 500 electrodes were implanted across all ten animals. The results demonstrated that chronic implantation (⩽8 weeks) of HD-USEAs into peripheral nerves can evoke behavioral deficits that recover over time. Morphology of the nerve distal to the implantation site showed variable signs of nerve fiber degeneration and regeneration. Cytology adjacent to the device-tissue interface also showed a variable response, with some electrodes having many macrophages surrounding the electrodes, while other electrodes had few or no macrophages present. This variability was also seen along the length of the electrodes. Axons remained within the proximity of the electrode tips at the distances required for theoretically effective stimulation and recording (⩽100 μm). We conclude from these studies that HD-USEAs do not cause overall global effects on the animals, at least up to the two-month period investigated here. These results demonstrate for the first time that the consequences of high-electrode count intrafascicular arrays compare with other peripheral nerve electrodes currently available for clinical or investigational neuromodulation.

Behavioral and cellular consequences of high-electrode count Utah Arrays chronically implanted in rat sciatic nerve

NASA Astrophysics Data System (ADS)

Wark, H. A. C.; Mathews, K. S.; Normann, R. A.; Fernandez, E.

2014-08-01

Objective. Before peripheral nerve electrodes can be used for the restoration of sensory and motor functions in patients with neurological disorders, the behavioral and histological consequences of these devices must be investigated. These indices of biocompatibility can be defined in terms of desired functional outcomes; for example, a device may be considered for use as a therapeutic intervention if the implanted subject retains functional neurons post-implantation even in the presence of a foreign body response. The consequences of an indwelling device may remain localized to cellular responses at the device-tissue interface, such as fibrotic encapsulation of the device, or they may affect the animal more globally, such as impacting behavioral or sensorimotor functions. The objective of this study was to investigate the overall consequences of implantation of high-electrode count intrafascicular peripheral nerve arrays, High Density Utah Slanted Electrode Arrays (HD-USEAs; 25 electrodes mm-2). Approach. HD-USEAs were implanted in rat sciatic nerves for one and two month periods. We monitored wheel running, noxious sensory paw withdrawal reflexes, footprints, nerve morphology and macrophage presence at the tissue-device interface. In addition, we used a novel approach to contain the arrays in actively behaving animals that consisted of an organic nerve wrap. A total of 500 electrodes were implanted across all ten animals. Main results. The results demonstrated that chronic implantation (⩽8 weeks) of HD-USEAs into peripheral nerves can evoke behavioral deficits that recover over time. Morphology of the nerve distal to the implantation site showed variable signs of nerve fiber degeneration and regeneration. Cytology adjacent to the device-tissue interface also showed a variable response, with some electrodes having many macrophages surrounding the electrodes, while other electrodes had few or no macrophages present. This variability was also seen along the length of the electrodes. Axons remained within the proximity of the electrode tips at the distances required for theoretically effective stimulation and recording (⩽100 μm). Significance. We conclude from these studies that HD-USEAs do not cause overall global effects on the animals, at least up to the two-month period investigated here. These results demonstrate for the first time that the consequences of high-electrode count intrafascicular arrays compare with other peripheral nerve electrodes currently available for clinical or investigational neuromodulation.

Micro-Reaction Chamber Electrodes for Neural Stimulation and Recording

PubMed Central

Shanmugasundaram, Balaji; Gluckman, Bruce J.

2012-01-01

Biocompatible electrodes with smaller geometric area are preferred to improve the selectivity of the neural recording and stimulation applications. We introduce the concept of a micro-reaction chamber (µRC) in which a volume within the electrode back plane is used to confine and sequester the electrochemical reactions used for charge passage. The µRC electrode design helps decrease impedance and improves the charge storage capacity without altering the geometry of the active site. Here we demonstrate that µRC electrodes fabricated from 50 µm diameter microwire have significantly improved charge storage capacity and lowered impedance at physiologically relevant frequencies in phosphate buffered saline solution compared with other designs. PMID:22254394

Multi-scale analysis of neural activity in humans: Implications for micro-scale electrocorticography.

PubMed

Kellis, Spencer; Sorensen, Larry; Darvas, Felix; Sayres, Conor; O'Neill, Kevin; Brown, Richard B; House, Paul; Ojemann, Jeff; Greger, Bradley

2016-01-01

Electrocorticography grids have been used to study and diagnose neural pathophysiology for over 50 years, and recently have been used for various neural prosthetic applications. Here we provide evidence that micro-scale electrodes are better suited for studying cortical pathology and function, and for implementing neural prostheses. This work compares dynamics in space, time, and frequency of cortical field potentials recorded by three types of electrodes: electrocorticographic (ECoG) electrodes, non-penetrating micro-ECoG (μECoG) electrodes that use microelectrodes and have tighter interelectrode spacing; and penetrating microelectrodes (MEA) that penetrate the cortex to record single- or multiunit activity (SUA or MUA) and local field potentials (LFP). While the finest spatial scales are found in LFPs recorded intracortically, we found that LFP recorded from μECoG electrodes demonstrate scales of linear similarity (i.e., correlation, coherence, and phase) closer to the intracortical electrodes than the clinical ECoG electrodes. We conclude that LFPs can be recorded intracortically and epicortically at finer scales than clinical ECoG electrodes are capable of capturing. Recorded with appropriately scaled electrodes and grids, field potentials expose a more detailed representation of cortical network activity, enabling advanced analyses of cortical pathology and demanding applications such as brain-computer interfaces. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Photoelectrocatalytic activity of a hydrothermally grown branched Zno nanorod-array electrode for paracetamol degradation.

PubMed

Lin, Chin Jung; Liao, Shu-Jun; Kao, Li-Cheng; Liou, Sofia Ya Hsuan

2015-06-30

Hierarchical branched ZnO nanorod (B-ZnR) arrays as an electrode for efficient photoelectrocatalytic degradation of paracetamol were grown on fluorine-doped tin oxide substrates using a solution route. The morphologic and structural studies show the ZnO trunks are single-crystalline hexagonal wurtzite ZnO with a [0001] growth direction and are densely covered by c-axis-oriented ZnO branches. The obvious enhancement in photocurrent response of the B-ZnR electrode was obtained than that in the ZnO nanoparticle (ZnO NP) electrode. For the photoelectrocatalytic degradation of paracetamol in 20 h, the conversion fraction of the drug increased from 32% over ZnO NP electrode to 62% over B-ZnR arrays with about 3-fold increase in initial reaction rate. The light intensity-dependent photoelectrocatalytic experiment indicated that the superior performance over the B-ZnR electrode was mainly ascribed to the increased specific surface area without significantly sacrificing the charge transport and pollutant diffusion efficiencies. Two aromatic intermediate compounds were observed and eventually converted into harmless carboxylic acids and ammonia. Hierarchical tree-like ZnO arrays can be considered effective alternatives to improve photoelectro degradation rates without the need for expensive additives. Copyright © 2015 Elsevier B.V. All rights reserved.

Carbon Nanofiber Nanoelectrodes for Biosensing Applications

NASA Technical Reports Server (NTRS)

Koehne, Jessica Erin

2014-01-01

A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

Perceptually aligning apical frequency regions leads to more binaural fusion of speech in a cochlear implant simulation.

PubMed

Staisloff, Hannah E; Lee, Daniel H; Aronoff, Justin M

2016-07-01

For bilateral cochlear implant users, the left and right arrays are typically not physically aligned, resulting in a degradation of binaural fusion, which can be detrimental to binaural abilities. Perceptually aligning the two arrays can be accomplished by disabling electrodes in one ear that do not have a perceptually corresponding electrode in the other side. However, disabling electrodes at the edges of the array will cause compression of the input frequency range into a smaller cochlear extent, which may result in reduced spectral resolution. An alternative approach to overcome this mismatch would be to only align one edge of the array. By aligning either only the apical or basal end of the arrays, fewer electrodes would be disabled, potentially causing less reduction in spectral resolution. The goal of this study was to determine the relative effect of aligning either the basal or apical end of the electrode with regards to binaural fusion. A vocoder was used to simulate cochlear implant listening conditions in normal hearing listeners. Speech signals were vocoded such that the two ears were either predominantly aligned at only the basal or apical end of the simulated arrays. The experiment was then repeated with a spectrally inverted vocoder to determine whether the detrimental effects on fusion were related to the spectral-temporal characteristics of the stimuli or the location in the cochlea where the misalignment occurred. In Experiment 1, aligning the basal portion of the simulated arrays led to significantly less binaural fusion than aligning the apical portions of the simulated array. However, when the input was spectrally inverted, aligning the apical portion of the simulated array led to significantly less binaural fusion than aligning the basal portions of the simulated arrays. These results suggest that, for speech, with its predominantly low frequency spectral-temporal modulations, it is more important to perceptually align the apical portion of the array to better preserve binaural fusion. By partially aligning these arrays, cochlear implant users could potentially increase their ability to fuse speech sounds presented to the two ears while maximizing spectral resolution. Copyright © 2016 Elsevier B.V. All rights reserved.

Step-By-Step Instructions for Retina Recordings with Perforated Multi Electrode Arrays

PubMed Central

Idrees, Saad; Mutter, Marion; Benkner, Boris; Münch, Thomas A.

2014-01-01

Multi-electrode arrays are a state-of-the-art tool in electrophysiology, also in retina research. The output cells of the retina, the retinal ganglion cells, form a monolayer in many species and are well accessible due to their proximity to the inner retinal surface. This structure has allowed the use of multi-electrode arrays for high-throughput, parallel recordings of retinal responses to presented visual stimuli, and has led to significant new insights into retinal organization and function. However, using conventional arrays where electrodes are embedded into a glass or ceramic plate can be associated with three main problems: (1) low signal-to-noise ratio due to poor contact between electrodes and tissue, especially in the case of strongly curved retinas from small animals, e.g. rodents; (2) insufficient oxygen and nutrient supply to cells located on the bottom of the recording chamber; and (3) displacement of the tissue during recordings. Perforated multi-electrode arrays (pMEAs) have been found to alleviate all three issues in brain slice recordings. Over the last years, we have been using such perforated arrays to study light evoked activity in the retinas of various species including mouse, pig, and human. In this article, we provide detailed step-by-step instructions for the use of perforated MEAs to record visual responses from the retina, including spike recordings from retinal ganglion cells and in vitro electroretinograms (ERG). In addition, we provide in-depth technical and methodological troubleshooting information, and show example recordings of good quality as well as examples for the various problems which might be encountered. While our description is based on the specific equipment we use in our own lab, it may also prove useful when establishing retinal MEA recordings with other equipment. PMID:25165854

Brightness field distributions of microlens arrays using micro molding.

PubMed

Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Yi; Shen, Yung-Kang

2010-12-20

This study describes the brightness field distributions of microlens arrays fabricated by micro injection molding (μIM) and micro injection-compression molding (μICM). The process for fabricating microlens arrays used room-temperature imprint lithography, photoresist reflow, electroforming, μIM, μICM, and optical properties measurement. Analytical results indicate that the brightness field distribution of the molded microlens arrays generated by μICM is better than those made using μIM. Our results further demonstrate that mold temperature is the most important processing parameter for brightness field distribution of molded microlens arrays made by μIM or μICM.

Method for manufacturing an electrochemical cell

DOEpatents

Kaun, Thomas D.; Eshman, Paul F.

1982-01-01

A secondary electrochemical cell is prepared by providing positive and negative electrodes having outer enclosures of rigid perforated electrically conductive material defining an internal compartment containing the electrode material in porous solid form. The electrodes are each immersed in molten electrolyte salt prior to cell assembly to incorporate the cell electrolyte. Following solidification of the electrolyte substantially throughout the porous volume of the electrode material, the electrodes are arranged in an alternating positive-negative array with interelectrode separators of porous frangible electrically insulative material. The completed array is assembled into the cell housing and sealed such that on heating the solidified electrolyte flows into the interelectrode separator.

Double interconnection fuel cell array

DOEpatents

Draper, Robert; Zymboly, Gregory E.

1993-01-01

A fuel cell array (10) is made, containing number of tubular, elongated fuel cells (12) which are placed next to each other in rows (A, B, C, D), where each cell contains inner electrodes (14) and outer electrodes (18 and 18'), with solid electrolyte (16 and 16') between the electrodes, where the electrolyte and outer electrode are discontinuous, having two portions, and providing at least two opposed discontinuities which contain at least two oppositely opposed interconnections (20 and 20') contacting the inner electrode (14), each cell (12) having only three metallic felt electrical connectors (22) which contact surrounding cells, where each row is electrically connected to the other.

High power density fuel cell comprising an array of microchannels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sopchak, David A; Morse, Jeffrey D; Upadhye, Ravindra S

2014-05-06

A phosphoric acid fuel cell according to one embodiment includes an array of microchannels defined by a porous electrolyte support structure extending between bottom and upper support layers, the microchannels including fuel and oxidant microchannels; fuel electrodes formed along some of the microchannels; and air electrodes formed along other of the microchannels. A method of making a phosphoric acid fuel cell according to one embodiment includes etching an array of microchannels in a substrate, thereby forming walls between the microchannels; processing the walls to make the walls porous, thereby forming a porous electrolyte support structure; forming anode electrodes along somemore » of the walls; forming cathode electrodes along other of the walls; and filling the porous electrolyte support structure with a phosphoric acid electrolyte. Additional embodiments are also disclosed.« less

Electrochemical properties of high-power supercapacitors using ordered NiO coated Si nanowire array electrodes

NASA Astrophysics Data System (ADS)

Lu, Fang; Qiu, Mengchun; Qi, Xiang; Yang, Liwen; Yin, Jinjie; Hao, Guolin; Feng, Xiang; Li, Jun; Zhong, Jianxin

2011-08-01

Highly ordered NiO coated Si nanowire arrays are fabricated as electrode materials for electrochemical supercapacitors (ES) via depositing Ni on electroless-etched Si nanowires and subsequently annealing. The electrochemical tests reveal that the constructed electrode has superior electrical conductibility and more active sites per unit area for chemical reaction processes, thereby possessing good cycle stability, high specific capacity, and low internal resistance. The specific capacity is up to 787.5 F g-1 at a discharge current of 2.5 mA and decreases slightly with 4.039% loss after 500 cycles, while the equivalent internal resistance is ˜3.067 Ω. Owing to its favorable electrochemical performance, this ordered hybrid array nanostructure is a promising electrode material in future commercial ES.

Curved Microneedle Array-Based sEMG Electrode for Robust Long-Term Measurements and High Selectivity

PubMed Central

Kim, Minjae; Kim, Taewan; Kim, Dong Sung; Chung, Wan Kyun

2015-01-01

Surface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode. PMID:26153773

The Design of Distributed Micro Grid Energy Storage System

NASA Astrophysics Data System (ADS)

Liang, Ya-feng; Wang, Yan-ping

2018-03-01

Distributed micro-grid runs in island mode, the energy storage system is the core to maintain the micro-grid stable operation. For the problems that it is poor to adjust at work and easy to cause the volatility of micro-grid caused by the existing energy storage structure of fixed connection. In this paper, an array type energy storage structure is proposed, and the array type energy storage system structure and working principle are analyzed. Finally, the array type energy storage structure model is established based on MATLAB, the simulation results show that the array type energy storage system has great flexibility, which can maximize the utilization of energy storage system, guarantee the reliable operation of distributed micro-grid and achieve the function of peak clipping and valley filling.

Fabrication and characterization of microfabricated on-chip microelectrochemical cell for biosensing applications

NASA Astrophysics Data System (ADS)

Said, N. A. Mohd; Twomey, K.; Herzog, G.; Ogurtsov, V. I.

2017-03-01

The fabrication of on-chip microelectrochemical cell on Si wafer by means of photolithography is described here. The single on-chip microelectrochemical cell device has dimensions of 100 × 380 mm with integrated Pt counter electrode (CE), Ag/AgCl reference electrode (RE) and gold microelectrode array of 500 nm recess depth as the working electrode (WE). Two geometries of electrode array were implemented, band and disc, with fixed diameter/width of 10 µm; and varied centre-to-centre spacing (d) and number of electrodes (N) in the array. The on-chip microelectrochemical cell structure has been designed to facilitate further WE biomodifications. Firstly, the developed microelectrochemical cell does not require packaging hence reducing the production cost and time. Secondly, the working electrode (WE) on the microelectrochemical cell is positioned towards the end of the chip enabling modification of the working electrode surface to be carried out for surface bio-functionalisation without affecting both the RE and CE surface conditions. The developed on-chip microelectrochemical cell was examined with scanning electron microscopy (SEM) and characterised by two electrochemical techniques. Both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were performed in 1 mM ferrocenecarboxylic acid (FCA) in 0.01 M phosphate buffered saline (PBS) solution at pH7.4. Electrochemical experiments showed that in the case of halving the interspacing distance of the microdisc WE array (50 nm instead of 100 nm), the voltammogram shifted from a steady-state CV (feature of hemispherical diffusion) to an inclined peak-shaped CV (feature of linear diffusion) albeit the arrays had the same surface area. In terms of EIS it was also found that linear diffusion dominates the surface instead of hemispherical diffusion once the interspacing distance was reduced, supporting the fact that closely packed arrays may behave like a macroelectrode

Laser direct-write and crystallization of FeSi II micro-dot array for NIR light-emitting device application

NASA Astrophysics Data System (ADS)

Narazaki, Aiko; Kurosaki, Ryozo; Sato, Tadatake; Kawaguchi, Yoshizo; Niino, Hiroyuki

2007-02-01

We printed FeSi II micro-dot array on various kinds of substrates utilizing laser-induced forward transfer (LIFT). An amorphous FeSi II was deposited by sputtering on a transparent plate as a source film. A single KrF excimer laser pulse through a mask-projection system was imaged with a small micrometer-sized grid pattern onto a film/plate interface, resulting in the deposition of FeSi II micro-dot array on a facing substrate with a high number density of 10 4 mm -2. FeSi II in the β crystalline phase is a promising eco-friendly semiconductor because of NIR electroluminescence used for optical networking as well as abundant components reserve on the earth and non-toxicity. However, the β-FeSi II film fabrication generally required high-temperature multi-processes which hamper its integration and performance reproducibility. Using the LIFT of micro-dot array, we succeeded in room-temperature preparation of β-FeSi II. Micro-Raman spectroscopy confirmed the β crystalline phase in the micro-dots deposited on an unheated silica glass substrate. Thus, the LIFT is useful for integrating functional micro-dot array accompanied by the crystallization at lower temperatures.

All-solid-state micro-supercapacitors based on inkjet printed graphene electrodes

NASA Astrophysics Data System (ADS)

Li, Jiantong; Mishukova, Viktoriia; Östling, Mikael

2016-09-01

The all-solid-state graphene-based in-plane micro-supercapacitors are fabricated simply through reliable inkjet printing of pristine graphene in interdigitated structure on silicon wafers to serve as both electrodes and current collectors, and a following drop casting of polymer electrolytes (polyvinyl alcohol/H3PO4). Benefiting from the printing processing, an attractive porous electrode microstructure with a large number of vertically orientated graphene flakes is observed. The devices exhibit commendable areal capacitance over 0.1 mF/cm2 and a long cycle life of over 1000 times. The simple and scalable fabrication technique for efficient micro-supercapacitors is promising for on-chip energy storage applications in emerging electronics.

Multifunctional potentiometric gas sensor array with an integrated temperature control and temperature sensors

DOEpatents

Blackburn, Bryan M; Wachsman, Eric D

2015-05-12

Embodiments of the subject invention relate to a gas sensor and method for sensing one or more gases. An embodiment incorporates an array of sensing electrodes maintained at similar or different temperatures, such that the sensitivity and species selectivity of the device can be fine tuned between different pairs of sensing electrodes. A specific embodiment pertains to a gas sensor array for monitoring combustion exhausts and/or chemical reaction byproducts. An embodiment of the subject device related to this invention operates at high temperatures and can withstand harsh chemical environments. Embodiments of the device are made on a single substrate. The devices can also be made on individual substrates and monitored individually as if they were part of an array on a single substrate. The device can incorporate sensing electrodes in the same environment, which allows the electrodes to be coplanar and, thus, keep manufacturing costs low. Embodiments of the device can provide improvements to sensitivity, selectivity, and signal interference via surface temperature control.

Bipolar battery with array of sealed cells

DOEpatents

Kaun, Thomas D.; Smaga, John A.

1987-01-01

A lithium alloy/metal sulfide battery as a dipolar battery is disclosed with an array of stacked cells with the anode and cathode electrode materials in each cell sealed in a confining structure and separated from one another except across separator material interposed therebetween. The separator material is contained in a module having separate perforated metallic sheets that sandwich opposite sides of the separator material for the cell and an annular insulating spacer that surrounds the separator material beyond the perforations and is also sandwiched between and sealed to the sheets. The peripheral edges of the sheets project outwardly beyond the spacer, traverse the side edges of the adjacent electrode material to form cup-like electrode holders, and are fused to the adjacent current collector or end face members of the array. Electrolyte is infused into the electrolyte cavity through the perforations of one of the metallic sheets with the perforations also functioning to allow ionic conductance across the separator material between the adjacent electrodes. A gas-tight housing provides an enclosure of the array.

Chemical and Biological Sensors Based on Organic Electrochemical Transistors

NASA Astrophysics Data System (ADS)

Lin, Peng

Organic thin film transistors (OTFTs) have been explored for sensing applications for several decades due to their many advantages like easy fabrication, low cost, flexibility, and biocompatibility. Among these OTFTs, organic electrochemical transistors (OECTs) have attracted a great deal of interest in recent years since the devices can operate stably in aqueous environment with relatively low working voltages and are suitable for applications in chemical and biological sensing. In this thesis, ion-sensitive properties of OECTs based on poly(3,4- ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) have been systematically studied. It was found that the gate electrode played an important role on the ion-sensitive properties of OECTs. For the devices with Ag/AgCl gate electrode, Nernstian relationships between the shift of gate voltage and the concentrations of cations were obtained. For the devices with Pt and Au gate electrodes, the ion sensitivities were higher than that given by Nernst equation, which could be attributed to the interface between the metal gate electrode and the electrolyte. Moreover, OECTs based on PEDOT:PSS were integrated into flexible microfluidic systems. Then a novel label-free DNA sensor was developed, in which single-stranded DNA probes were immobilized on the surface of Au gate electrode. These devices successfully detected complementary DNA targets at concentrations as low as 1 nM. The detection limit was also extended to 10 pM by pulse-enhanced hybridization process of DNA. OECTs based on PEDOT:PSS were also exploited as cell-based biosensors. Human esophageal squamous epithelial cancer cell lines (KYSE30) and fibroblast cell lines (HFFI) were successfully grown on the surface of PEDOT:PSS film. Then the devices were used for in-vitro monitoring cell activities when the living cells were treated by trypsin and an anti-cancer drug, retinoic acid. It was found that the devices were sensitive to the change of surface charge and morphology of adherent cells. Finally, micro-dimensional OECT arrays were fabricated by photolithography. The fabrication process was mainly divided into three steps, i.e. fabrication of gold electrodes, fabrication of PEDOT:PSS films, and fabrication of PEG mirowells. Compared with macro-dimensional OECTs, micro-dimensional OECTs showed better electrical performance, such as faster response time and better stability in aqueous solution.

Parylene C-Based Flexible Electronics for pH Monitoring Applications

PubMed Central

Trantidou, Tatiana; Tariq, Mehvesh; Terracciano, Cesare M.; Toumazou, Christofer; Prodromakis, Themistoklis

2014-01-01

Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H+ sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm) of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s) system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26–0.38 mV/min). The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues. PMID:24988379

Parylene C-based flexible electronics for pH monitoring applications.

PubMed

Trantidou, Tatiana; Tariq, Mehvesh; Terracciano, Cesare M; Toumazou, Christofer; Prodromakis, Themistoklis

2014-07-01

Emerging materials in the field of implantable sensors should meet the needs for biocompatibility; transparency; flexibility and integrability. In this work; we present an integrated approach for implementing flexible bio-sensors based on thin Parylene C films that serve both as flexible support substrates and as active H(+) sensing membranes within the same platform. Using standard micro-fabrication techniques; a miniaturized 40-electrode array was implemented on a 5 μm-thick Parylene C film. A thin capping film (1 μm) of Parylene on top of the array was plasma oxidized and served as the pH sensing membrane. The sensor was evaluated with the use of extended gate discrete MOSFETs to separate the chemistry from the electronics and prolong the lifetime of the sensor. The chemical sensing array spatially maps the local pH levels; providing a reliable and rapid-response (<5 s) system with a sensitivity of 23 mV/pH. Moreover; it preserves excellent encapsulation integrity and low chemical drifts (0.26-0.38 mV/min). The proposed approach is able to deliver hybrid flexible sensing platforms that will facilitate concurrent electrical and chemical recordings; with application in real-time physiological recordings of organs and tissues.

Fabrication and Testing of a Modular Micro-Pocket Fission Detector Instrumentation System for Test Nuclear Reactors

NASA Astrophysics Data System (ADS)

Reichenberger, Michael A.; Nichols, Daniel M.; Stevenson, Sarah R.; Swope, Tanner M.; Hilger, Caden W.; Roberts, Jeremy A.; Unruh, Troy C.; McGregor, Douglas S.

2018-01-01

Advancements in nuclear reactor core modeling and computational capability have encouraged further development of in-core neutron sensors. Measurement of the neutron-flux distribution within the reactor core provides a more complete understanding of the operating conditions in the reactor than typical ex-core sensors. Micro-Pocket Fission Detectors have been developed and tested previously but have been limited to single-node operation and have utilized highly specialized designs. The development of a widely deployable, multi-node Micro-Pocket Fission Detector assembly will enhance nuclear research capabilities. A modular, four-node Micro-Pocket Fission Detector array was designed, fabricated, and tested at Kansas State University. The array was constructed from materials that do not significantly perturb the neutron flux in the reactor core. All four sensor nodes were equally spaced axially in the array to span the fuel-region of the reactor core. The array was filled with neon gas, serving as an ionization medium in the small cavities of the Micro-Pocket Fission Detectors. The modular design of the instrument facilitates the testing and deployment of numerous sensor arrays. The unified design drastically improved device ruggedness and simplified construction from previous designs. Five 8-mm penetrations in the upper grid plate of the Kansas State University TRIGA Mk. II research nuclear reactor were utilized to deploy the array between fuel elements in the core. The Micro-Pocket Fission Detector array was coupled to an electronic support system which has been specially developed to support pulse-mode operation. The Micro-Pocket Fission Detector array composed of four sensors was used to monitor local neutron flux at a constant reactor power of 100 kWth at different axial locations simultaneously. The array was positioned at five different radial locations within the core to emulate the deployment of multiple arrays and develop a 2-dimensional measurement of neutron flux in the reactor core.

Characteristics for electrochemical machining with nanoscale voltage pulses.

PubMed

Lee, E S; Back, S Y; Lee, J T

2009-06-01

Electrochemical machining has traditionally been used in highly specialized fields, such as those of the aerospace and defense industries. It is now increasingly being applied in other industries, where parts with difficult-to-cut material, complex geometry and tribology, and devices of nanoscale and microscale are required. Electric characteristic plays a principal function role in and chemical characteristic plays an assistant function role in electrochemical machining. Therefore, essential parameters in electrochemical machining can be described current density, machining time, inter-electrode gap size, electrolyte, electrode shape etc. Electrochemical machining provides an economical and effective method for machining high strength, high tension and heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. The application of nanoscale voltage pulses between a tool electrode and a workpiece in an electrochemical environment allows the three-dimensional machining of conducting materials with sub-micrometer precision. In this study, micro probe are developed by electrochemical etching and micro holes are manufactured using these micro probe as tool electrodes. Micro holes and microgroove can be accurately achieved by using nanoscale voltages pulses.

An electrocorticographic electrode array for simultaneous recording from medial, lateral, and intrasulcal surface of the cortex in macaque monkeys

PubMed Central

Fukushima, Makoto; Saunders, Richard C.; Mullarkey, Matthew; Doyle, Alexandra M.; Mishkin, Mortimer; Fujii, Naotaka

2014-01-01

Background Electrocorticography (ECoG) permits recording electrical field potentials with high spatiotemporal resolution over a large part of the cerebral cortex. Application of chronically implanted ECoG arrays in animal models provides an opportunity to investigate global spatiotemporal neural patterns and functional connectivity systematically under various experimental conditions. Although ECoG is conventionally used to cover the gyral cortical surface, recent studies have shown the feasibility of intrasulcal ECoG recordings in macaque monkeys. New Method Here we developed a new ECoG array to record neural activity simultaneously from much of the medial and lateral cortical surface of a single hemisphere, together with the supratemporal plane (STP) of the lateral sulcus in macaque monkeys. The ECoG array consisted of 256 electrodes for bipolar recording at 128 sites. Results We successfully implanted the ECoG array in the left hemisphere of three rhesus monkeys. The electrodes in the auditory and visual cortex detected robust event related potentials to auditory and visual stimuli, respectively. Bipolar recording from adjacent electrode pairs effectively eliminated chewing artifacts evident in monopolar recording, demonstrating the advantage of using the ECoG array under conditions that generate significant movement artifacts. Comparison with Existing Methods Compared with bipolar ECoG arrays previously developed for macaque monkeys, this array significantly expands the number of cortical target areas in gyral and intralsulcal cortex. Conclusions This new ECoG array provides an opportunity to investigate global network interactions among gyral and intrasulcal cortical areas. PMID:24972186

Highly stretchable resistive pressure sensors using a conductive elastomeric composite on a micropyramid array.

PubMed

Choong, Chwee-Lin; Shim, Mun-Bo; Lee, Byoung-Sun; Jeon, Sanghun; Ko, Dong-Su; Kang, Tae-Hyung; Bae, Jihyun; Lee, Sung Hoon; Byun, Kyung-Eun; Im, Jungkyun; Jeong, Yong Jin; Park, Chan Eon; Park, Jong-Jin; Chung, U-In

2014-06-04

A stretchable resistive pressure sensor is achieved by coating a compressible substrate with a highly stretchable electrode. The substrate contains an array of microscale pyramidal features, and the electrode comprises a polymer composite. When the pressure-induced geometrical change experienced by the electrode is maximized at 40% elongation, a sensitivity of 10.3 kPa(-1) is achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thin-film-transistor array: an exploratory attempt for high throughput cell manipulation using electrowetting principle

NASA Astrophysics Data System (ADS)

Shaik, F. Azam; Cathcart, G.; Ihida, S.; Lereau-Bernier, M.; Leclerc, E.; Sakai, Y.; Toshiyoshi, H.; Tixier-Mita, A.

2017-05-01

In lab-on-a-chip (LoC) devices, microfluidic displacement of liquids is a key component. electrowetting on dielectric (EWOD) is a technique to move fluids, with the advantage of not requiring channels, pumps or valves. Fluids are discretized into droplets on microelectrodes and moved by applying an electric field via the electrodes to manipulate the contact angle. Micro-objects, such as biological cells, can be transported inside of these droplets. However, the design of conventional microelectrodes, made by standard micro-fabrication techniques, fixes the path of the droplets, and limits the reconfigurability of paths and thus limits the parallel processing of droplets. In that respect, thin film transistor (TFT) technology presents a great opportunity as it allows infinitely reconfigurable paths, with high parallelizability. We propose here to investigate the possibility of using TFT array devices for high throughput cell manipulation using EWOD. A COMSOL based 2D simulation coupled with a MATLAB algorithm was used to simulate the contact angle modulation, displacement and mixing of droplets. These simulations were confirmed by experimental results. The EWOD technique was applied to a droplet of culture medium containing HepG2 carcinoma cells and demonstrated no negative effects on the viability of the cells. This confirms the possibility of applying EWOD techniques to cellular applications, such as parallel cell analysis.

Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors.

PubMed

Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

2011-05-01

Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g(-1) at 1 A g(-1), which remained at 543 F g(-1) when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg(-1)) was maintained even at a high power density of 6000 W kg(-1). An excellent long cycle life of the electrode was observed with a retention of ∼86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO(2) nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications. © The Royal Society of Chemistry 2011

Feasibility of microelectrode array (MEA) based on silicone-polyimide hybrid for retina prosthesis.

PubMed

Kim, Eui Tae; Kim, Cinoo; Lee, Seung Woo; Seo, Jong-Mo; Chung, Hum; Kim, Sung June

2009-09-01

To adopt micropatterning technology in manufacturing silicone elastomer-based microelectrode arrays for retinal stimulation, a silicone-polyimide hybrid microelectrode array was proposed and tested in vivo. Gold microelectrodes were created by semiconductor manufacturing technology based on polyimide and were hybridized with silicone elastomer by spin coating. The stability of the hybrid between the two materials was flex and blister tested. The feasibility of the hybrid electrode was evaluated in the rabbit eye by reviewing optical coherence tomography (OCT) findings after suprachoroidal implantation. The flex test showed no dehiscence between the two materials for 24 hours of alternative flexion and extension from -45.0 degrees to +45.0 degrees . During the blister test, delamination was observed at 8.33 +/- 1.36 psi of pressure stress; however, this property was improved to 11.50 +/- 1.04 psi by oxygen plasma treatment before hybridization. OCT examination revealed that the implanted electrodes were safely located in the suprachoroidal space during the 4-week follow-up period. The silicone-polyimide hybrid microelectrode array showed moderate physical properties, which are suitable for in vivo application. Appropriate pretreatment before hybridization improved electrode stability. In vivo testing indicated that this electrode is suitable as a stimulation electrode in artificial retina.

Are tomorrow's micro-supercapacitors hidden in a forest of silicon nanotrees?

NASA Astrophysics Data System (ADS)

Thissandier, Fleur; Gentile, Pascal; Brousse, Thierry; Bidan, Gérard; Sadki, Saïd

2014-12-01

Silicon nanotrees (SiNTrs) have been grown by Chemical Vapor Deposition (CVD) via gold catalysis and a three steps process: trunks and branches growth are separated by a new gold catalyst deposition. The influence of growth conditions and the second gold catalyst deposition method on SiNTrs morphology are investigated. SiNTrs based electrodes show a capacitive behavior and better capacitance than the corresponding silicon nanowires (SiNWs) electrode. Electrode capacitance is increased up to 900 μF cm-2, i.e. 150 fold higher than for bulk silicon. Micro-supercapacitors with SiNTrs electrodes have a remarkable stability (only 1.2% loses of their initial capacitance after more than one million cycles). The use of an ionic liquid based electrolyte leads to a high maximum power density (around 225 mW cm-2) which is competitive with Onion Like Carbon based micro-supercapacitors.

Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for micro-supercapacitors in solid Nafion electrolyte

NASA Astrophysics Data System (ADS)

Gnerlich, Markus; Ben-Yoav, Hadar; Culver, James N.; Ketchum, Douglas R.; Ghodssi, Reza

2015-10-01

A three-dimensional micro-supercapacitor has been developed using a novel bottom-up assembly method combining genetically modified Tobacco mosaic virus (TMV-1Cys), photolithographically defined micropillars and selective deposition of ruthenium oxide on multi-metallic microelectrodes. The three-dimensional microelectrodes consist of a titanium nitride current collector with two functionalized areas: (1) gold coating on the active electrode area promotes TMV-1Cys adhesion, and (2) sacrificial nickel pads dissolve in ruthenium tetroxide plating solution to produce ruthenium oxide on all electrically connected areas. The microfabricated electrodes are arranged in an interdigitated pattern, and the capacitance per electrode has been measured as high as 203 mF cm-2 with solid Nafion electrolyte. The process integration of bio-templated ruthenium oxide with microfabricated electrodes and solid electrolyte is an important advance towards the energy storage needs of mass produced self-sufficient micro-devices.

Macro-/Micro-Controlled 3D Lithium-Ion Batteries via Additive Manufacturing and Electric Field Processing.

PubMed

Li, Jie; Liang, Xinhua; Liou, Frank; Park, Jonghyun

2018-01-30

This paper presents a new concept for making battery electrodes that can simultaneously control macro-/micro-structures and help address current energy storage technology gaps and future energy storage requirements. Modern batteries are fabricated in the form of laminated structures that are composed of randomly mixed constituent materials. This randomness in conventional methods can provide a possibility of developing new breakthrough processing techniques to build well-organized structures that can improve battery performance. In the proposed processing, an electric field (EF) controls the microstructures of manganese-based electrodes, while additive manufacturing controls macro-3D structures and the integration of both scales. The synergistic control of micro-/macro-structures is a novel concept in energy material processing that has considerable potential for providing unprecedented control of electrode structures, thereby enhancing performance. Electrochemical tests have shown that these new electrodes exhibit superior performance in their specific capacity, areal capacity, and life cycle.

Selective deposition of nanostructured ruthenium oxide using Tobacco mosaic virus for micro-supercapacitors in solid Nafion electrolyte

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gnerlich, Markus; Ben-Yoav, Hadar; Culver, James N.

A three-dimensional micro-supercapacitor has been developed using a novel bottom-up assembly method combining genetically modified Tobacco mosaic virus (TMV-1Cys), photolithographically defined micropillars and selective deposition of ruthenium oxide on multi-metallic microelectrodes. The three-dimensional microelectrodes consist of a titanium nitride current collector with two functionalized areas: (1) gold coating on the active electrode area promotes TMV-1Cys adhesion, and (2) sacrificial nickel pads dissolve in ruthenium tetroxide plating solution to produce ruthenium oxide on all electrically connected areas. The microfabricated electrodes are arranged in an interdigitated pattern, and the capacitance per electrode has been measured as high as 203 mF cm-2 withmore » solid Nafion electrolyte. The process integration of bio-templated ruthenium oxide with microfabricated electrodes and solid electrolyte is an important advance towards the energy storage needs of mass produced self-sufficient micro-devices.« less

Reliability of spring interconnects for high channel-count polyimide electrode arrays

NASA Astrophysics Data System (ADS)

Khan, Sharif; Ordonez, Juan Sebastian; Stieglitz, Thomas

2018-05-01

Active neural implants with a high channel-count need robust and reliable operational assembly for the targeted environment in order to be classified as viable fully implantable systems. The discrete functionality of the electrode array and the implant electronics is vital for intact assembly. A critical interface exists at the interconnection sites between the electrode array and the implant electronics, especially in hybrid assemblies (e.g. retinal implants) where electrodes and electronics are not on the same substrate. Since the interconnects in such assemblies cannot be hermetically sealed, reliable protection against the physiological environment is essential for delivering high insulation resistance and low defusibility of salt ions, which are limited in complexity by current assembly techniques. This work reports on a combination of spring-type interconnects on a polyimide array with silicone rubber gasket insulation for chronically active implantable systems. The spring design of the interconnects on the backend of the electrode array compensates for the uniform thickness of the sandwiched gasket during bonding in assembly and relieves the propagation of extrinsic stresses to the bulk polyimide substrate. The contact resistance of the microflex-bonded spring interconnects with the underlying metallized ceramic test vehicles and insulation through the gasket between adjacent contacts was investigated against the MIL883 standard. The contact and insulation resistances remained stable in the exhausting environmental conditions.

A versatile all-channel stimulator for electrode arrays, with real-time control

PubMed Central

Wagenaar, Daniel A; Potter, Steve M

2008-01-01

Over the last few decades, technology to record through ever increasing numbers of electrodes has become available to electrophysiologists. For the study of distributed neural processing, however, the ability to stimulate through equal numbers of electrodes, and thus to attain bidirectional communication, is of paramount importance. Here, we present a stimulation system for multi-electrode arrays which interfaces with existing commercial recording hardware, and allows stimulation through any electrode in the array, with rapid switching between channels. The system is controlled through real-time Linux, making it extremely flexible: stimulation sequences can be constructed on-the-fly, and arbitrary stimulus waveforms can be used if desired. A key feature of this design is that it can be readily and inexpensively reproduced in other labs, since it interfaces to standard PC parallel ports and uses only off-the-shelf components. Moreover, adaptation for use with in vivo multi-electrode probes would be straightforward. In combination with our freely available data-acquisition software, MeaBench, this system can provide feedback stimulation in response to recorded action potentials within 15 ms. PMID:15876621

Localized electrical stimulation of in vitro neurons using an array of sub-cellular sized electrodes.

PubMed

Braeken, Dries; Huys, Roeland; Loo, Josine; Bartic, Carmen; Borghs, Gustaaf; Callewaert, Geert; Eberle, Wolfgang

2010-12-15

The investigation of single-neuron parameters is of great interest because many aspects in the behavior and communication of neuronal networks still remain unidentified. However, the present available techniques for single-cell measurements are slow and do not allow for a high-throughput approach. We present here a CMOS compatible microelectrode array with 84 electrodes (with diameters ranging from 1.2 to 4.2 μm) that are smaller than the size of cell, thereby supporting single-cell addressability. We show controllable electroporation of a single cell by an underlying electrode while monitoring changes in the intracellular membrane potential. Further, by applying a localized electrical field between two electrodes close to a neuron while recording changes in the intracellular calcium concentration, we demonstrate activation of a single cell (∼270%, DF/F(0)), followed by a network response of the neighboring cells. The technology can be easily scaled up to larger electrode arrays (theoretically up to 137,000 electrodes/mm(2)) with active CMOS electronics integration able to perform high-throughput measurements on single cells. Copyright © 2010 Elsevier B.V. All rights reserved.

Active C4 Electrodes for Local Field Potential Recording Applications

PubMed Central

Wang, Lu; Freedman, David; Sahin, Mesut; Ünlü, M. Selim; Knepper, Ronald

2016-01-01

Extracellular neural recording, with multi-electrode arrays (MEAs), is a powerful method used to study neural function at the network level. However, in a high density array, it can be costly and time consuming to integrate the active circuit with the expensive electrodes. In this paper, we present a 4 mm × 4 mm neural recording integrated circuit (IC) chip, utilizing IBM C4 bumps as recording electrodes, which enable a seamless active chip and electrode integration. The IC chip was designed and fabricated in a 0.13 μm BiCMOS process for both in vitro and in vivo applications. It has an input-referred noise of 4.6 μVrms for the bandwidth of 10 Hz to 10 kHz and a power dissipation of 11.25 mW at 2.5 V, or 43.9 μW per input channel. This prototype is scalable for implementing larger number and higher density electrode arrays. To validate the functionality of the chip, electrical testing results and acute in vivo recordings from a rat barrel cortex are presented. PMID:26861324

Selective in situ potential-assisted SAM formation on multi electrode arrays

NASA Astrophysics Data System (ADS)

Haag, Ann-Lauriene; Toader, Violeta; Lennox, R. Bruce; Grutter, Peter

2016-11-01

The selective modification of individual components in a biosensor array is challenging. To address this challenge, we present a generalizable approach to selectively modify and characterize individual gold surfaces in an array, in an in situ manner. This is achieved by taking advantage of the potential dependent adsorption/desorption of surface-modified organic molecules. Control of the applied potential of the individual sensors in an array where each acts as a working electrode provides differential derivatization of the sensor surfaces. To demonstrate this concept, two different self-assembled monolayer (SAM)-forming electrochemically addressable ω-ferrocenyl alkanethiols (C11) are chemisorbed onto independent but spatially adjacent gold electrodes. The ferrocene alkanethiol does not chemisorb onto the surface when the applied potential is cathodic relative to the adsorption potential and the electrode remains underivatized. However, applying potentials that are modestly positive relative to the adsorption potential leads to extensive coverage within 10 min. The resulting SAM remains in a stable state while held at potentials <200 mV above the adsorption potential. In this state, the chemisorbed SAM does not significantly desorb nor do new ferrocenylalkythiols adsorb. Using three set applied potentials provides for controlled submonolayer alkylthiol marker coverage of each independent gold electrode. These three applied potentials are dependent upon the specifics of the respective adsorbate. Characterization of the ferrocene-modified electrodes via cyclic voltammetry demonstrates that each specific ferrocene marker is exclusively adsorbed to the desired target electrode.

Facile synthesis of hierarchical Co3O4@MnO2 core-shell arrays on Ni foam for asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Huang, Ming; Zhang, Yuxin; Li, Fei; Zhang, Lili; Wen, Zhiyu; Liu, Qing

2014-04-01

Hierarchical Co3O4@MnO2 core-shell arrays on Ni foam have been fabricated by a facile hydrothermal approach and further investigated as the electrode for high-performance supercapacitors. Owing to the high conductivity of the well-defined mesoporous Co3O4 nanowire arrays in combination with the large surface area provided by the ultrathin MnO2 nanosheets, the unique designed Co3O4@MnO2 core-shell arrays on Ni foam have exhibited a high specific capacitance (560 F g-1 at a current density of 0.2 A g-1), good rate capability, and excellent cycling stability (95% capacitance retention after 5000 cycles). An asymmetric supercapacitor with Co3O4@MnO2 core-shell nanostructure as the positive electrode and activated microwave exfoliated graphite oxide activated graphene (MEGO) as the negative electrode yielded an energy density of 17.7 Wh kg-1 and a maximum power density of 158 kW kg-1. The rational design of the unique core-shell array architectures demonstrated in this work provides a new and facile approach to fabricate high-performance electrode for supercapacitors.

Novel iron oxide nanotube arrays as high-performance anodes for lithium ion batteries

NASA Astrophysics Data System (ADS)

Zhong, Yuan; Fan, Huiqing; Chang, Ling; Shao, Haibo; Wang, Jianming; Zhang, Jianqing; Cao, Chu-nan

2015-11-01

Nanostructured iron oxides can be promising anode materials for lithium ion batteries (LIBs). However, improvement on the rate capability and/or electrochemical cycling stability of iron oxide anode materials remains a key challenge because of their poor electrical conductivities and large volume expansion during cycling. Herein, the vertically aligned arrays of one-dimensional (1D) iron oxide nanotubes with 5.8 wt% carbon have been fabricated by a novel surfactant-free self-corrosion process and subsequent thermal treatment. The as-fabricated nanotube array electrode delivers a reversible capacity of 932 mAh g-1 after 50 charge-discharge cycles at a current of 0.6 A g-1. The electrode still shows a reversible capacity of 610 mAh g-1 even at a very high rate (8.0 A g-1), demonstrating its prominent rate capability. Furthermore, the nanotube array electrode also exhibits the excellent electrochemical cycling stability with a reversible capacity of 880 mAh g-1 after 500 cycles at a current of 4 A g-1. The nanotube array electrode with superior lithium storage performance reveals the promising potential as a high-performance anode for LIBs.

Redox hydrogel based bienzyme electrode for L-glutamate monitoring.

PubMed

Belay, A; Collins, A; Ruzgas, T; Kissinger, P T; Gorton, L; Csöregi, E

1999-02-01

Amperometric bienzyme electrodes based on coupled L-glutamate oxidase (GlOx) and horseradish peroxidase (HRP) were constructed for the direct monitoring of L-glutamate in a flow injection (FI)-system. The bienzyme electrodes were constructed by coating solid graphite rods with a premixed solution containing GlOx and HRP crosslinked with a redox polymer formed of poly(1-vinylimidazole) complexed with (osmium (4-4'-dimethylbpy)2 Cl)II/III. Poly(ethylene glycol) diglycidyl ether (PEGDGE) was used as the crosslinker and the modified electrodes were inserted as the working electrode in a conventional three electrode flow through amperometric cell operated at -0.05 V versus Ag¿AgCl (0.1 M KCl). The bienzyme electrode was optimized with regard to wire composition, Os-loading of the wires, enzyme ratios, coating procedure, flow rate, effect of poly(ethyleneimine) addition, etc. The optimized electrodes were characterized by a sensitivity of 88.36 +/- 0.14 microA mM(-1) cm(-2), a detection limit of 0.3 microM (calculated as three times the signal-to-noise ratio), a response time of less than 10 s and responded linearly between 0.3 and 250 microM (linear regression coefficient = 0.999) with an operational stability of only 3% sensitivity loss during 8 h of continuous FI operation at a sample throughput of 30 injections h(-1).

Copper vertical micro dendrite fin arrays and their superior boiling heat transfer capability

NASA Astrophysics Data System (ADS)

Wang, Ya-Qiao; Lyu, Shu-Shen; Luo, Jia-Li; Luo, Zhi-Yong; Fu, Yuan-Xiang; Heng, Yi; Zhang, Jian-Hui; Mo, Dong-Chuan

2017-11-01

Micro pin fin arrays have been widely used in electronic cooling, micro reactors, catalyst support, and wettability modification and so on, and a facile way to produce better micro pin fin arrays is demanded. Herein, a simple electrochemical method has been developed to fabricate copper vertical micro dendrite fin arrays (Cu-VMDFA) with controllable shapes, number density and height. High copper sulphate concentration is one key point to make the dendrite stand vertically. Besides, the applied current should rise at an appropriate rate to ensure the copper dendrite can grow vertically on its own. The Cu-VMDFA can significantly enhance the heat transfer coefficient by approximately twice compared to the plain copper surface. The Cu-VMDFA may be widely used in boiling heat transfer areas such as nuclear power plants, electronic cooling, heat exchangers, and so on.

Amperometric micro pH measurements in oxygenated saliva.

PubMed

Chaisiwamongkhol, Korbua; Batchelor-McAuley, Christopher; Compton, Richard G

2017-07-24

An amperometric micro pH sensor has been developed based on the chemical oxidation of carbon fibre surfaces (diameter of 9 μm and length of ca. 1 mm) to enhance the population of surface quinone groups for the measurement of salivary pH. The pH analysis utilises the electrochemically reversible two-electron, two-proton behaviour of surface quinone groups on the micro-wire electrodes. A Nernstian response is observed across the pH range 2-8 which is the pH range of many biological fluids. We highlight the measurement of pH in small volumes of biological fluids without the need for oxygen removal and specifically the micro pH electrode is examined by measuring the pH of commercial synthetic saliva and authentic human saliva samples. The results correspond well with those obtained by using commercial glass pH electrodes on large volume samples.

Micro-machined resonator

DOEpatents

Godshall, N.A.; Koehler, D.R.; Liang, A.Y.; Smith, B.K.

1993-03-30

A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

Micro-machined resonator

DOEpatents

Godshall, Ned A.; Koehler, Dale R.; Liang, Alan Y.; Smith, Bradley K.

1993-01-01

A micro-machined resonator, typically quartz, with upper and lower micro-machinable support members, or covers, having etched wells which may be lined with conductive electrode material, between the support members is a quartz resonator having an energy trapping quartz mesa capacitively coupled to the electrode through a diaphragm; the quartz resonator is supported by either micro-machined cantilever springs or by thin layers extending over the surfaces of the support. If the diaphragm is rigid, clock applications are available, and if the diaphragm is resilient, then transducer applications can be achieved. Either the thin support layers or the conductive electrode material can be integral with the diaphragm. In any event, the covers are bonded to form a hermetic seal and the interior volume may be filled with a gas or may be evacuated. In addition, one or both of the covers may include oscillator and interface circuitry for the resonator.

The effect of thermal annealing on pentacene thin film transistor with micro contact printing.

PubMed

Shin, Hong-Sik; Yun, Ho-Jin; Baek, Kyu-Ha; Ham, Yong-Hyun; Park, Kun-Sik; Kim, Dong-Pyo; Lee, Ga-Won; Lee, Hi-Deok; Lee, Kijun; Do, Lee-Mi

2012-07-01

We used micro contact printing (micro-CP) to fabricate inverted coplanar pentacene thin film transistors (TFTs) with 1-microm channels. The patterning of micro-scale source/drain electrodes without etch process was successfully achieved using Polydimethylsiloxane (PDMS) elastomer stamp. We used the Ag nano particle ink as an electrode material, and the sheet resistance and surface roughness of the Ag electrodes were effectively reduced with the 2-step thermal annealing on a hotplate, which improved the mobility, the on-off ratio, and the subthreshold slope (SS) of the pentacene TFTs. In addition, the device annealing on a hotplate in a N2 atmosphere for 30 sec can enhance the off-current and the mobility properties of OTFTs without damaging the pentacene thin films and increase the adhesion between pentacene and dielectric layer (SiO2), which was investigated with the pentacene films phase change of the XRD spectrum after device annealing.

Direct laser writing for micro-optical devices using a negative photoresist.

PubMed

Tsutsumi, Naoto; Hirota, Junichi; Kinashi, Kenji; Sakai, Wataru

2017-12-11

Direct laser writing (DLW) via two-photon absorption (TPA) has attracted much attention as a new microfabrication technique because it can be applied to fabricate complex, three-dimensional (3D) microstructures. In this study, 3D microstructures and micro-optical devices of micro-lens array on the micrometer scale are fabricated using the negative photoresist SU-8 through TPA with a femtosecond laser pulse under a microscope. The effects of the irradiation conditions on linewidths, such as laser power, writing speed, and writing cycles (a number of times a line is overwritten), are investigated before the fabrication of the 3D microstructures. Various microstructures such as woodpiles, hemisphere and microstructures, 3D micro-lens and micro-lens array for micro-optical devices are fabricated. The shape of the micro-lens is evaluated using the shape analysis mode of a laser microscope to calculate the working distance of the fabricated micro-lenses. The calculated working distance corresponds well to the experimentally measured value. The focusing performance of the fabricated micro-lens is confirmed by the TPA fluorescence of an isopropyl thioxanthone (ITX) ethanol solution excited by a Ti:sapphire femtosecond laser at 800 nm. Micro-lens array (assembled 9 micro-lenses) are fabricated. Nine independent woodpile structures are simultaneously manufactured by DLW via TPA to confirm the multi-focusing ability using the fabricated micro-lens array.

Microtitrimetry by differential electrolytic potentiometry using metallic electrodes and nanomaterials modified metallic electrodes

NASA Astrophysics Data System (ADS)

Amro, Abdulaziz Nabil

For the first time silver wire electrodes have been coated with carbon nanotubes using floating catalyst chemical vapor deposition (CVD) method. The production of CNTs has been conducted in a horizontal tubular reactor. Acetylene gas was used as a carbon source. Ferrocene has been used as a catalyst precursor for the growth of CNT. Different parameters have been optimized to get a high yield of CNTs and ensure their growth on the silver electrodes using univariate method. The parameters studied include the hydrogen flow rate, acetylene flow rate, temperature of the furnace, time of the reaction and the location of the electrodes in the reactor tube. The optimum conditions for those parameters were: for hydrogen and acetylene, the flow rates were 25 mL /min and 75 mL / min respectively. The furnace temperature was found to be 700 °C and the reaction time was 15 minutes. Regarding the location of the silver wires it should be located in the first 10 cm of the front side of the tube. Scanning electron microscopy (SEM) and transition electron microscopy (TEM) have been used to characterize carbon on silver electrodes. According to the experimental results, TEM figures show that CNT produced on Silver wire is multiwall carbon nanotubes MWCNT. Silver electrodes either pure or coated with CNT were used as indicating systems in micro titration using both dc differential electrolytic potentiometry (DEP) and mark-space bias DEP techniques. All types of titrimetric reactions were investigated using different types of electrodes like Pt and gold for oxidation reduction titrations, antimony electrodes for acid base titrations, silver electrodes for precipitation titrations in addition to Ag-CNT electrodes. End points at volumes of 1 microL were determined. Different parameters were optimized like the current density, the percentage bias, the volume of the sample and the concentrations of the reactants. Microtitrimetry has been applied on several types of analytes; Ferrous, Ascorbic acid, chloride, Cyanide, Sodium Bicarbonate and Ketoconazole in aqueous and non- aqueous medium. The performance of Ag-CNT electrodes was found to be much better than the normal silver electrodes. The differential titration curves obtained were symmetrical with significant heights. For silver electrodes coated with CNT the first derivative of the potential was found to give better curves than the normal differential curves, hence the end point location was successfully achieved. A micro liter injector that can deliver volumes at a micro liter level was designed and fabricated. Microtitrimetry which requires volumes of reagents at the micro liter level can offer a solution to the large consumption of reagents in all classical titrimetric processes. Hence, large savings in reagents as well as less waste will reach the environment.

Optimal Micro-Jet Flow Control for Compact Air Vehicle Inlets

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Miller, Daniel N.; Addington, Gregory A.; Agrell, Johan

2004-01-01

The purpose of this study on micro-jet secondary flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to optimally design micro-jet secondary flow control arrays, and to establish that the aeromechanical effects of engine face distortion can also be included in the design and optimization process. These statistical design concepts were used to investigate the design characteristics of "low mass" micro-jet array designs. The term "low mass" micro-jet may refers to fluidic jets with total (integrated) mass flow ratios between 0.10 and 1.0 percent of the engine face mass flow. Therefore, this report examines optimal micro-jet array designs for compact inlets through a Response Surface Methodology.

Neurotoxicity testing using Microelectrode Arrays (MEAs): a growing trend

EPA Science Inventory

Microelectrode arrays (MEAs) are groups of extracellular electrodes that are 10-30 microns in diameter and can be utilized in vivo or in vitro. For in vitro uses, an MEA typically contains up to 64 electrodes and can be utilized to measure the activity of cells and tissues that a...

Fabrication of Flexible Microneedle Array Electrodes for Wearable Bio-Signal Recording

PubMed Central

Ren, Lei; Xu, Shujia; Gao, Jie; Lin, Zi; Chen, Zhipeng; Liu, Bin; Liang, Liang; Jiang, Lelun

2018-01-01

Laser-direct writing (LDW) and magneto-rheological drawing lithography (MRDL) have been proposed for the fabrication of a flexible microneedle array electrode (MAE) for wearable bio-signal monitoring. Conductive patterns were directly written onto the flexible polyethylene terephthalate (PET) substrate by LDW. The microneedle array was rapidly drawn and formed from the droplets of curable magnetorheological fluid with the assistance of an external magnetic field by MRDL. A flexible MAE can maintain a stable contact interface with curved human skin due to the flexibility of the PET substrate. Compared with Ag/AgCl electrodes and flexible dry electrodes (FDE), the electrode–skin interface impedance of flexible MAE was the minimum even after a 50-cycle bending test. Flexible MAE can record electromyography (EMG), electroencephalography (EEG) and static electrocardiography (ECG) signals with good fidelity. The main features of the dynamic ECG signal recorded by flexible MAE are the most distinguishable with the least moving artifacts. Flexible MAE is an attractive candidate electrode for wearable bio-signal monitoring. PMID:29652835

COMMUNICATION: Minocycline increases quality and longevity of chronic neural recordings

NASA Astrophysics Data System (ADS)

Rennaker, R. L.; Miller, J.; Tang, H.; Wilson, D. A.

2007-06-01

Brain/machine interfaces could potentially be used in the treatment of a host of neurological disorders ranging from paralysis to sensory deficits. Insertion of chronic micro-electrode arrays into neural tissue initiates a host of immunological responses, which typically leads to the formation of a cellular sheath around the implant, resulting in the loss of useful signals. Minocycline has been shown to have neuroprotective and neurorestorative effects in certain neural injury and neurodegenerative disease models. This study examined the effects of minocycline administration on the quality and longevity of chronic multi-channel microwire neural implants 1 week and 1 month post-implantation in auditory cortex. The mean signal-to-noise ratio for the minocycline group stabilized at the end of week 1 and remained above 4.6 throughout the following 3 weeks. The control group signal-to-noise ratio dropped throughout the duration of the study and at the end of 4 weeks was 2.6. Furthermore, 68% of electrodes from the minocycline group showed significant stimulus-driven activity at week 4 compared to 12.5% of electrodes in the control group. There was a significant reduction in the number of activated astrocytes around the implant in minocycline subjects, as well as a reduction in total area occupied by activated astrocytes at 1 and 4 weeks.

Reduced Synchronization Persistence in Neural Networks Derived from Atm-Deficient Mice

PubMed Central

Levine-Small, Noah; Yekutieli, Ziv; Aljadeff, Jonathan; Boccaletti, Stefano; Ben-Jacob, Eshel; Barzilai, Ari

2011-01-01

Many neurodegenerative diseases are characterized by malfunction of the DNA damage response. Therefore, it is important to understand the connection between system level neural network behavior and DNA. Neural networks drawn from genetically engineered animals, interfaced with micro-electrode arrays allowed us to unveil connections between networks’ system level activity properties and such genome instability. We discovered that Atm protein deficiency, which in humans leads to progressive motor impairment, leads to a reduced synchronization persistence compared to wild type synchronization, after chemically imposed DNA damage. Not only do these results suggest a role for DNA stability in neural network activity, they also establish an experimental paradigm for empirically determining the role a gene plays on the behavior of a neural network. PMID:21519382

Design and Application of Multi-functional Electrogenerated Chemiluminescence Imaging Analyzer.

PubMed

Jiang, Guangfu; Liu, Xia; Wang, Yaqin; Ruan, Sanpeng; Qi, Honglan; Yang, Yong; Zhou, Qishe; Zhang, Chengxiao

2016-01-01

A multi-functional eletrogenerated chemiluminescence (ECL) imaging analyzer including both a photomultiplier tube and charged coupled device as detectors has been developed. The ECL imaging analyzer can effectively work for electrochemical study, ECL intensity detection at electrode array, and ECL imaging at bipolar electrodes or electrode array. As an ECL imaging example, an ECL biosensor for visual detection of matrix metalloproteinase 7 in the range from 0.05 to 1 ng/mL is demonstrated.

Ion manipulation device to prevent loss of ions

DOEpatents

Tolmachev, Aleksey; Smith, Richard D; Ibrahim, Yehia M; Anderson, Gordon A; Baker, Erin M

2015-03-03

An ion manipulation method and device to prevent loss of ions is disclosed. The device includes a pair of surfaces. An inner array of electrodes is coupled to the surfaces. A RF voltage and a DC voltage are alternately applied to the inner array of electrodes. The applied RF voltage is alternately positive and negative so that immediately adjacent or nearest neighbor RF applied electrodes are supplied with RF signals that are approximately 180 degrees out of phase.

Interdigitated array of Pt electrodes for electrical stimulation and engineering of aligned muscle tissue.

PubMed

Ahadian, Samad; Ramón-Azcón, Javier; Ostrovidov, Serge; Camci-Unal, Gulden; Hosseini, Vahid; Kaji, Hirokazu; Ino, Kosuke; Shiku, Hitoshi; Khademhosseini, Ali; Matsue, Tomokazu

2012-09-21

Engineered skeletal muscle tissues could be useful for applications in tissue engineering, drug screening, and bio-robotics. It is well-known that skeletal muscle cells are able to differentiate under electrical stimulation (ES), with an increase in myosin production, along with the formation of myofibers and contractile proteins. In this study, we describe the use of an interdigitated array of electrodes as a novel platform to electrically stimulate engineered muscle tissues. The resulting muscle myofibers were analyzed and quantified in terms of their myotube characteristics and gene expression. The engineered muscle tissues stimulated through the interdigitated array of electrodes demonstrated superior performance and maturation compared to the corresponding tissues stimulated through a conventional setup (i.e., through Pt wires in close proximity to the muscle tissue). In particular, the ES of muscle tissue (voltage 6 V, frequency 1 Hz and duration 10 ms for 1 day) through the interdigitated array of electrodes resulted in a higher degree of C2C12 myotube alignment (∼80%) as compared to ES using Pt wires (∼65%). In addition, higher amounts of C2C12 myotube coverage area, myotube length, muscle transcription factors and protein biomarkers were found for myotubes stimulated through the interdigitated array of electrodes compared to those stimulated using the Pt wires. Due to the wide array of potential applications of ES for two- and three-dimensional (2D and 3D) engineered tissues, the suggested platform could be employed for a variety of cell and tissue structures to more efficiently investigate their response to electrical fields.

Carbon Nanofiber Nanoelectrodes for Neural Stimulation and Chemical Detection: The Era of "Smart" Deep Brain Stimulation

NASA Technical Reports Server (NTRS)

Koehne, Jessica E.

2016-01-01

A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

Carbon Nanofiber Nanoelectrodes for Neural Stimulation and Chemical Detection: The Era of Smart Deep Brain Stimulation

NASA Technical Reports Server (NTRS)

Koehne, Jessica E.

2016-01-01

A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report two studies using vertically aligned CNF nanoelectrodes for biomedical applications. CNF arrays are investigated as neural stimulation and neurotransmitter recording electrodes for application in deep brain stimulation (DBS). Polypyrrole coated CNF nanoelectrodes have shown great promise as stimulating electrodes due to their large surface area, low impedance, biocompatibility and capacity for highly localized stimulation. CNFs embedded in SiO2 have been used as sensing electrodes for neurotransmitter detection. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable "smart" therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

Liquid-crystal microlenses with patterned ring-electrode arrays for multiple-mode two-dimensional imaging

NASA Astrophysics Data System (ADS)

Xie, Xingwang; Han, Xinjie; Long, Huabao; Dai, Wanwan; Xin, Zhaowei; Wei, Dong; Zhang, Xinyu; Wang, Haiwei; Xie, Changsheng

2018-02-01

In this paper, a new liquid-crystal microlens array (LCMLA) with patterned ring-electrode arrays (PREAs) is investigated, which has an ability to acquire multiple-mode two-dimensional images with better electrically tunable efficiency than common liquid-crystal devices. The new type of LCMLA can be used to overcome several remarkable disadvantage of conventional liquid-crystal microlens arrays switched and adjusted electrically by relatively complex mechanism. There are two layer electrodes in the LCMLA developed by us. The top electrode layer consists of PREAs with different featured diameter but the same center for each single cell, and the bottom is a plate electrode. When both electrode structures are driven independently by variable AC voltage signal, a gradient electric field distribution could be obtained, which can drive liquid-crystal molecules to reorient themselves along the gradient electric field shaped, so as to demonstrate a satisfactory refractive index distribution. The common experiments are carried out to validate the performances needed. As shown, the focal length of the LCMLA can be adjusted continuously according to the variable voltage signal applied. According to designing, the LCMLA will be integrated continuously with an image sensors to set up a camera with desired performances. The test results indicate that our camera based on the LCMLA can obtain distinct multiple-mode two-dimensional images under the condition of using relatively low driving signal voltage.

Hydrogen peroxide biosensor based on microperoxidase-11 immobilized in a silica cavity array electrode.

PubMed

Tian, Shu; Zhou, Qun; Gu, Zhuomin; Gu, Xuefang; Zhao, Lili; Li, Yan; Zheng, Junwei

2013-03-30

Hydrogen peroxide biosensor based on the silica cavity array modified indium-doped tin oxide (ITO) electrode was constructed. An array of silica microcavities was fabricated by electrodeposition using the assembled polystyrene particles as template. Due to the resistance gradient of the silica cavity structure, the silica cavity exhibits a confinement effect on the electrochemical reactions, making the electrode function as an array of "soft" microelectrodes. The covalently immobilized microperoxidase-11(MP-11) inside these SiO2 cavities can keep its physiological activities, the electron transfer between the MP-11 and electrode was investigated through electrochemical method. The cyclic voltammetric curve shows a quasi-reversible electrochemical redox behavior with a pair of well-defined redox peaks, the cathodic and anodic peaks are located at -0.26 and -0.15V. Furthermore, the modified electrode exhibits high electrocatalytic activity toward the reduction of hydrogen peroxide and also shows good analytical performance for the amperometric detection of H2O2 with a linear range from 2×10(-6) to 6×10(-4)M. The good reproducibility and long-term stability of this novel electrode not only offer an opportunity for the detection of H2O2 in low concentration, but also provide a platform to construct various biosensors based on many other enzymes. Copyright © 2013 Elsevier B.V. All rights reserved.

Technical and clinical analysis of microEEG: a miniature wireless EEG device designed to record high-quality EEG in the emergency department

PubMed Central

2012-01-01

Background We describe and characterize the performance of microEEG compared to that of a commercially available and widely used clinical EEG machine. microEEG is a portable, battery-operated, wireless EEG device, developed by Bio-Signal Group to overcome the obstacles to routine use of EEG in emergency departments (EDs). Methods The microEEG was used to obtain EEGs from healthy volunteers in the EEG laboratory and ED. The standard system was used to obtain EEGs from healthy volunteers in the EEG laboratory, and studies recorded from patients in the ED or ICU were also used for comparison. In one experiment, a signal splitter was used to record simultaneous microEEG and standard EEG from the same electrodes. Results EEG signal analysis techniques indicated good agreement between microEEG and the standard system in 66 EEGs recorded in the EEG laboratory and the ED. In the simultaneous recording the microEEG and standard system signals differed only in a smaller amount of 60 Hz noise in the microEEG signal. In a blinded review by a board-certified clinical neurophysiologist, differences in technical quality or interpretability were insignificant between standard recordings in the EEG laboratory and microEEG recordings from standard or electrode cap electrodes in the ED or EEG laboratory. The microEEG data recording characteristics such as analog-to-digital conversion resolution (16 bits), input impedance (>100MΩ), and common-mode rejection ratio (85 dB) are similar to those of commercially available systems, although the microEEG is many times smaller (88 g and 9.4 × 4.4 × 3.8 cm). Conclusions Our results suggest that the technical qualities of microEEG are non-inferior to a standard commercially available EEG recording device. EEG in the ED is an unmet medical need due to space and time constraints, high levels of ambient electrical noise, and the cost of 24/7 EEG technologist availability. This study suggests that using microEEG with an electrode cap that can be applied easily and quickly can surmount these obstacles without compromising technical quality. PMID:23006616

Reducing interaction in simultaneous paired stimulation with CI.

PubMed

Vellinga, Dirk; Bruijn, Saskia; Briaire, Jeroen J; Kalkman, Randy K; Frijns, Johan H M

2017-01-01

In this study simultaneous paired stimulation of electrodes in cochlear implants is investigated by psychophysical experiments in 8 post-lingually deaf subjects (and one extra subject who only participated in part of the experiments). Simultaneous and sequential monopolar stimulation modes are used as references and are compared to channel interaction compensation, partial tripolar stimulation and a novel sequential stimulation strategy named phased array compensation. Psychophysical experiments are performed to investigate both the loudness integration during paired stimulation at the main electrodes as well as the interaction with the electrode contact located halfway between the stimulating pair. The study shows that simultaneous monopolar stimulation has more loudness integration on the main electrodes and more interaction in between the electrodes than sequential stimulation. Channel interaction compensation works to reduce the loudness integration at the main electrodes, but does not reduce the interaction in between the electrodes caused by paired stimulation. Partial tripolar stimulation uses much more current to reach the needed loudness, but shows the same interaction in between the electrodes as sequential monopolar stimulation. In phased array compensation we have used the individual impedance matrix of each subject to calculate the current needed on each electrode to exactly match the stimulation voltage along the array to that of sequential stimulation. The results show that the interaction in between the electrodes is the same as monopolar stimulation. The strategy uses less current than partial tripolar stimulation, but more than monopolar stimulation. In conclusion, the paper shows that paired stimulation is possible if the interaction is compensated.

Simple and fast method for fabrication of endoscopic implantable sensor arrays.

PubMed

Tahirbegi, I Bogachan; Alvira, Margarita; Mir, Mònica; Samitier, Josep

2014-06-26

Here we have developed a simple method for the fabrication of disposable implantable all-solid-state ion-selective electrodes (ISE) in an array format without using complex fabrication equipment or clean room facilities. The electrodes were designed in a needle shape instead of planar electrodes for a full contact with the tissue. The needle-shape platform comprises 12 metallic pins which were functionalized with conductive inks and ISE membranes. The modified microelectrodes were characterized with cyclic voltammetry, scanning electron microscope (SEM), and optical interferometry. The surface area and roughness factor of each microelectrode were determined and reproducible values were obtained for all the microelectrodes on the array. In this work, the microelectrodes were modified with membranes for the detection of pH and nitrate ions to prove the reliability of the fabricated sensor array platform adapted to an endoscope.

Membrane Bioprobe Electrodes

ERIC Educational Resources Information Center

Rechnitz, Garry A.

1975-01-01

Describes the design of ion selective electrodes coupled with immobilized enzymes which operate either continuously or on drop-sized samples. Cites techniques for urea, L-phenylalanine and amygdalin. Micro size electrodes for use in single cells are discussed. (GH)

Novel anti-reflection technology for GaAs single-junction solar cells using surface patterning and Au nanoparticles.

PubMed

Kim, Youngjo; Lam, Nguyen Dinh; Kim, Kangho; Kim, Sangin; Rotermund, Fabian; Lim, Hanjo; Lee, Jaejin

2012-07-01

Single-junction GaAs solar cell structures were grown by low-pressure MOCVD on GaAs (100) substrates. Micro-rod arrays with diameters of 2 microm, 5 microm, and 10 microm were fabricated on the surfaces of the GaAs solar cells via photolithography and wet chemical etching. The patterned surfaces were coated with Au nanoparticles using an Au colloidal solution. Characteristics of the GaAs solar cells with and without the micro-rod arrays and Au nanoparticles were investigated. The short-circuit current density of the GaAs solar cell with 2 microm rod arrays and Au nanoparticles increased up to 34.9% compared to that of the reference cell without micro-rod arrays and Au nanoparticles. The conversion efficiency of the GaAs solar cell that was coated with Au nanoparticles on the patterned surface with micro-rod arrays can be improved from 14.1% to 19.9% under 1 sun AM 1.5G illumination. These results show that micro-rod arrays and Au nanoparticle coating can be applied together in surface patterning to achieve a novel cost-effective anti-reflection technology.

Cortical activation following chronic passive implantation of a wide-field suprachoroidal retinal prosthesis

NASA Astrophysics Data System (ADS)

Villalobos, Joel; Fallon, James B.; Nayagam, David A. X.; Shivdasani, Mohit N.; Luu, Chi D.; Allen, Penelope J.; Shepherd, Robert K.; Williams, Chris E.

2014-08-01

Objective. The research goal is to develop a wide-field retinal stimulating array for prosthetic vision. This study aimed at evaluating the efficacy of a suprachoroidal electrode array in evoking visual cortex activity after long term implantation. Approach. A planar silicone based electrode array (8 mm × 19 mm) was implanted into the suprachoroidal space in cats (ntotal = 10). It consisted of 20 platinum stimulating electrodes (600 μm diameter) and a trans-scleral cable terminated in a subcutaneous connector. Three months after implantation (nchronic = 6), or immediately after implantation (nacute = 4), an electrophysiological study was performed. Electrode total impedance was measured from voltage transients using 500 μs, 1 mA pulses. Electrically evoked potentials (EEPs) and multi-unit activity were recorded from the visual cortex in response to monopolar retinal stimulation. Dynamic range and cortical activation spread were calculated from the multi-unit recordings. Main results. The mean electrode total impedance in vivo following 3 months was 12.5 ± 0.3 kΩ. EEPs were recorded for 98% of the electrodes. The median evoked potential threshold was 150 nC (charge density 53 μC cm-2). The lowest stimulation thresholds were found proximal to the area centralis. Mean thresholds from multiunit activity were lower for chronic (181 ± 14 nC) compared to acute (322 ± 20 nC) electrodes (P < 0.001), but there was no difference in dynamic range or cortical activation spread. Significance. Suprachoroidal stimulation threshold was lower in chronic than acute implantation and was within safe charge limits for platinum. Electrode-tissue impedance following chronic implantation was higher, indicating the need for sufficient compliance voltage (e.g. 12.8 V for mean impedance, threshold and dynamic range). The wide-field suprachoroidal array reliably activated the retina after chronic implantation.

Development of a Wireless Brain Implant: The Telemetric Electrode Array System (TEAS) Project

DTIC Science & Technology

2001-10-25

8 array connected to an electronic system through a special polyimide flexible cable. The neuronal signals recorded by the electrode array at 1 mm...deposition prior to applying an insulation coating of glass using electron-beam deposition or a biocompatible epoxy through a dipping process. In the case...layer can be made relatively easily, by melting and cooling glass powder or curing biocompatible epoxy, it was desirable to simplify the process and

Ten-channel InP-based large-scale photonic integrated transmitter fabricated by SAG technology

NASA Astrophysics Data System (ADS)

Zhang, Can; Zhu, Hongliang; Liang, Song; Cui, Xiao; Wang, Huitao; Zhao, Lingjuan; Wang, Wei

2014-12-01

A 10-channel InP-based large-scale photonic integrated transmitter was fabricated by selective area growth (SAG) technology combined with butt-joint regrowth (BJR) technology. The SAG technology was utilized to fabricate the electroabsorption modulated distributed feedback (DFB) laser (EML) arrays at the same time. The design of coplanar electrodes for electroabsorption modulator (EAM) was used for the flip-chip bonding package. The lasing wavelength of DFB laser could be tuned by the integrated micro-heater to match the ITU grids, which only needs one electrode pad. The average output power of each channel is 250 μW with an injection current of 200 mA. The static extinction ratios of the EAMs for 10 channels tested are ranged from 15 to 27 dB with a reverse bias of 6 V. The frequencies of 3 dB bandwidth of the chip for each channel are around 14 GHz. The novel design and simple fabrication process show its enormous potential in reducing the cost of large-scale photonic integrated circuit (LS-PIC) transmitter with high chip yields.

Solution of the Inverse Problem for Thin Film Patterning by Electrohydrodynamic Forces

NASA Astrophysics Data System (ADS)

Zhou, Chengzhe; Troian, Sandra

2017-11-01

Micro- and nanopatterning techniques for applications ranging from optoelectronics to biofluidics have multiplied in number over the past decade to include adaptations of mature technologies as well as novel lithographic techniques based on periodic spatial modulation of surface stresses. We focus here on one such technique which relies on shape changes in nanofilms responding to a patterned counter-electrode. The interaction of a patterned electric field with the polarization charges at the liquid interface causes a patterned electrostatic pressure counterbalanced by capillary pressure which leads to 3D protrusions whose shape and evolution can be terminated as needed. All studies to date, however, have investigated the evolution of the liquid film in response to a preset counter-electrode pattern. In this talk, we present solution of the inverse problem for the thin film equation governing the electrohydrodynamic response by treating the system as a transient control problem. Optimality conditions are derived and an efficient corresponding solution algorithm is presented. We demonstrate such implementation of film control to achieve periodic, free surface shapes ranging from simple circular cap arrays to more complex square and sawtooth patterns.

Hydrothermally formed three-dimensional hexagon-like P doped Ni(OH)2 rod arrays for high performance all-solid-state asymmetric supercapacitors

NASA Astrophysics Data System (ADS)

Li, Kunzhen; Li, Shikuo; Huang, Fangzhi; Lu, Yan; Wang, Lei; Chen, Hong; Zhang, Hui

2018-01-01

Three dimensional hexagon-like phosphrous (P) doped Ni(OH)2 rod arrays grown on Ni foam (NF) are fabricated by a facile and green one-step hydrothermal process. Ni foam is only reacted in a certain concentration of P containing H2O2 aqueous solution. The possible growth mechanism of the P doped Ni(OH)2 rod arrays is discussed. As a battery-type electrode material in situ formed on Ni foam, the binder-free P doped Ni(OH)2 rod arrays electrode displays a ultrahigh specific areal capacitance of 2.11C cm-2 (3.51 F cm-2) at 2 mA cm-2, and excellent cycling stability (95.5% capacitance retention after 7500 cycles). The assembled all-solid-state asymmetric supercapacitor (AAS) based on such P doped Ni(OH)2 rod arrays as the positive electrode and activated carbon as the negative electrode achieves an energy density of 81.3 Wh kg-1 at the power density of 635 W kg-1. The AAS device also exhibits excellent practical performance, which can easily drive an electric fan (3 W rated power) when two AAS devices are assembled in series. Thus, our synthesized P doped Ni(OH)2 rod arrays has a lot of potential applications in future energy storage prospects.

Abiotic-biotic characterization of Pt/Ir microelectrode arrays in chronic implants

PubMed Central

Prasad, Abhishek; Xue, Qing-Shan; Dieme, Robert; Sankar, Viswanath; Mayrand, Roxanne C.; Nishida, Toshikazu; Streit, Wolfgang J.; Sanchez, Justin C.

2014-01-01

Pt/Ir electrodes have been extensively used in neurophysiology research in recent years as they provide a more inert recording surface as compared to tungsten or stainless steel. While floating microelectrode arrays (FMA) consisting of Pt/Ir electrodes are an option for neuroprosthetic applications, long-term in vivo functional performance characterization of these FMAs is lacking. In this study, we have performed comprehensive abiotic-biotic characterization of Pt/Ir arrays in 12 rats with implant periods ranging from 1 week up to 6 months. Each of the FMAs consisted of 16-channel, 1.5 mm long, and 75 μm diameter microwires with tapered tips that were implanted into the somatosensory cortex. Abiotic characterization included (1) pre-implant and post-explant scanning electron microscopy (SEM) to study recording site changes, insulation delamination and cracking, and (2) chronic in vivo electrode impedance spectroscopy. Biotic characterization included study of microglial responses using a panel of antibodies, such as Iba1, ED1, and anti-ferritin, the latter being indicative of blood-brain barrier (BBB) disruption. Significant structural variation was observed pre-implantation among the arrays in the form of irregular insulation, cracks in insulation/recording surface, and insulation delamination. We observed delamination and cracking of insulation in almost all electrodes post-implantation. These changes altered the electrochemical surface area of the electrodes and resulted in declining impedance over the long-term due to formation of electrical leakage pathways. In general, the decline in impedance corresponded with poor electrode functional performance, which was quantified via electrode yield. Our abiotic results suggest that manufacturing variability and insulation material as an important factor contributing to electrode failure. Biotic results show that electrode performance was not correlated with microglial activation (neuroinflammation) as we were able to observe poor performance in the absence of neuroinflammation, as well as good performance in the presence of neuroinflammation. One biotic change that correlated well with poor electrode performance was intraparenchymal bleeding, which was evident macroscopically in some rats and presented microscopically by intense ferritin immunoreactivity in microglia/macrophages. Thus, we currently consider intraparenchymal bleeding, suboptimal electrode fabrication, and insulation delamination as the major factors contributing toward electrode failure. PMID:24550823

Concentric-electrode organic electrochemical transistors: case study for selective hydrazine sensing

NASA Astrophysics Data System (ADS)

Pecqueur, S.; Lenfant, S.; Guérin, D.; Alibart, F.; Vuillaume, D.

2017-12-01

We report on hydrazine-sensing organic electrochemical transistors (OECTs) with a design consisting in concentric annular electrodes. The design engineering of these OECTs was motivated by the great potential of using OECT sensing arrays in fields such as bioelectronics. In this work, PEDOT:PSS-based OECTs have been studied as aqueous sensors, specifically sensitive to the lethal hydrazine molecule. These amperometric sensors have many relevant features for the development of hydrazine sensors, such as a sensitivity down to 10-5 M of hydrazine in water, an order of magnitude higher selectivity for hydrazine than for 9 other water soluble common analytes, the capability to recover entirely its base signal after water flushing and a very low voltage operation. The specificity for hydrazine to be sensed by our OECTs is caused by its catalytic oxidation at the gate electrode and enables increasing the output current modulation of the devices. This has permitted the device-geometry study of the whole series of 80 micrometric OECT devices with sub-20-nm PEDOT:PSS layers, channel lengths down to 1 μm and a specific device geometry of coplanar and concentric electrodes. The numerous geometries unravel new aspects of the OECT mechanisms governing the electrochemical sensing behaviours of the device, more particularly the effect of the contacts which are inherent at the micro-scale. By lowering the device cross-talking, micrometric gate-integrated radial OECTs shall contribute to the diminishing of the readout invasiveness and therefore promotes further the development of OECT biosensors.

Fully integrated three-dimensional electrodes for electrochemical detection in microchips: fabrication, characterization, and applications.

PubMed

Pai, Rekha S; Walsh, Kevin M; Crain, Mark M; Roussel, Thomas J; Jackson, Douglas J; Baldwin, Richard P; Keynton, Robert S; Naber, John F

2009-06-15

A scalable and rather inexpensive solution to producing microanalytical systems with "on-chip" three-dimensional (3D) microelectrodes is presented in this study, along with applicability to practical electrochemical (EC) detection scenarios such as preconcentration and interferant removal. This technique to create high-aspect-ratio (as much as 4:1) gold microstructures in constrained areas involved the modification of stud bump geometry with microfabricated silicon molds via an optimized combination of temperature, pressure, and time. The microelectrodes that resulted consisted of an array of square pillars approximately 18 microm tall and 20 microm wide on each side, placed at the end of a microfabricated electrophoresis channel. This technique increased the active surface area of the microelectrodes by as much as a factor of 50, while mass transfer and, consequently, preconcentration collection efficiencies were increased to approximately 100%, compared to approximately 30% efficiency for planar nonmodified microelectrodes (samples that were used included the neurotransmitters dopamine and catechol). The 3D microelectrodes were used both in a stand-alone configuration, for direct EC detection of model catecholamine analytes, and, more interestingly, in dual electrode configurations for EC sample processing prior to detection downstream at a second planar electrode. In particular, the 3D electrodes were shown to be capable of performing coulometry or complete (100%) redox conversion of analyte species over a wide range of concentrations, from 4.3 microM to 4.4 mM, in either plug-flow or continuous-flow formats.

High performance flexible pH sensor based on polyaniline nanopillar array electrode.

PubMed

Yoon, Jo Hee; Hong, Seok Bok; Yun, Seok-Oh; Lee, Seok Jae; Lee, Tae Jae; Lee, Kyoung G; Choi, Bong Gill

2017-03-15

Flexible pH sensor technologies have attracted a great deal of attention in many applications, such as, wearable health care devices and monitors for chemical and biological processes. Here, we fabricated flexible and thin pH sensors using a two electrode configuration comprised of a polyaniline nanopillar (PAN) array working electrode and an Ag/AgCl reference electrode. In order to provide nanostructure, soft lithography using a polymeric blend was employed to create a flexible nanopillar backbone film. Polyaniline-sensing materials were deposited on a patterned-nanopillar array by electrochemical deposition. The pH sensors produced exhibited a near-Nernstian response (∼60.3mV/pH), which was maintained in a bent state. In addition, pH sensors showed other excellent sensor performances in terms of response time, reversibility, repeatability, selectivity, and stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Factors Affecting Outcomes in Cochlear Implant Recipients Implanted With a Perimodiolar Electrode Array Located in Scala Tympani.

PubMed

Holden, Laura K; Firszt, Jill B; Reeder, Ruth M; Uchanski, Rosalie M; Dwyer, Noël Y; Holden, Timothy A

2016-12-01

To identify primary biographic and audiologic factors contributing to cochlear implant (CI) performance variability in quiet and noise by controlling electrode array type and electrode position within the cochlea. Although CI outcomes have improved over time, considerable outcome variability still exists. Biographic, audiologic, and device-related factors have been shown to influence performance. Examining CI recipients with consistent array type and electrode position may allow focused investigation into outcome variability resulting from biographic and audiologic factors. Thirty-nine adults (40 ears) implanted for at least 6 months with a perimodiolar electrode array known (via computed tomography [CT] imaging) to be in scala tympani participated. Test materials, administered CI only, included monosyllabic words, sentences in quiet and noise, and spectral ripple discrimination. In quiet, scores were high with mean word and sentence scores of 76 and 87%, respectively; however, sentence scores decreased by an average of 35 percentage points when noise was added. A principal components (PC) analysis of biographic and audiologic factors found three distinct factors, PC1 Age, PC2 Duration, and PC3 Pre-op Hearing. PC1 Age was the only factor that correlated, albeit modestly, with speech recognition in quiet and noise. Spectral ripple discrimination strongly correlated with speech measures. For these recipients with consistent electrode position, PC1 Age was related to speech recognition performance. Consistent electrode position may have contributed to high speech understanding in quiet. Inter-subject variability in noise may have been influenced by auditory/cognitive processing, known to decline with age, and mechanisms that underlie spectral resolution ability.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates and Method Relating Thereto

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Claire, Terry L. (Inventor)

2002-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared, This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches. adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrates; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Thermally Stable, Piezoelectric and Pyroelectric Polymeric Substrates

NASA Technical Reports Server (NTRS)

Simpson, Joycely O. (Inventor); St.Clair, Terry L. (Inventor)

1999-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers. acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors, in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors. weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 1000 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium; applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

Method of Making Thermally Stable, Piezoelectric and Proelectric Polymeric Substrates

NASA Technical Reports Server (NTRS)

Simpson, Joycelyn O. (Inventor); St.Clair, Terry L. (Inventor)

1999-01-01

A thermally stable, piezoelectric and pyroelectric polymeric substrate was prepared. This thermally stable, piezoelectric and pyroelectric polymeric substrate may be used to prepare electromechanical transducers, thermomechanical transducers, accelerometers, acoustic sensors, infrared sensors, pressure sensors, vibration sensors, impact sensors. in-situ temperature sensors, in-situ stress/strain sensors, micro actuators, switches, adjustable fresnel lenses, speakers, tactile sensors, weather sensors, micro positioners, ultrasonic devices, power generators, tunable reflectors, microphones, and hydrophones. The process for preparing these polymeric substrates includes: providing a polymeric substrate having a softening temperature greater than 100 C; depositing a metal electrode material onto the polymer film; attaching a plurality of electrical leads to the metal electrode coated polymeric substrate; heating the metal electrode coated polymeric substrate in a low dielectric medium: applying a voltage to the heated metal electrode coated polymeric substrate to induce polarization; and cooling the polarized metal electrode coated polymeric electrode while maintaining a constant voltage.

High-Performance Flexible All-Solid-State Asymmetric Supercapacitors Based on Vertically Aligned CuSe@Co(OH) 2 Nanosheet Arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Jiangfeng; Tian, Yazhou; Yang, Ziyuan

The developments of electrode active materials provide the opportunities for next-generation energy storage devices. The arrangement of electrode materials on the substrate has recently emerged as a promising strategy for preparing high-performance supercapacitors. In this paper, we demonstrate a novel vertically aligned CuSe@Co(OH) 2 nanosheet arrays electrode for supercapacitor application. The materials are thoroughly characterized by structural and spectroscopic techniques. Electrochemical performance of CuSe@Co(OH) 2 nanosheet arrays are investigated in detail, which exhibit a specific capacitance as much as 1180 F g -1 at a current density of 1 A g -1. A flexible asymmetric all-solid-state supercapacitor is fabricated usingmore » CuSe@Co(OH) 2 nanosheet arrays as the positive electrode and activated carbon as the negative electrode. The device delivers a volumetric capacitance of 441.4 mF cm -3 with maximum energy density and maximum power density is 0.17 and 62.1 mW cm -3, as well as robust cycling stability (~80.4% capacitance retention after 10 000 cycles), excellent flexibility, and mechanical stability. Finally, the excellent electrochemical performance can be attributed to its unique vertically aligned configuration.« less

High-Performance Flexible All-Solid-State Asymmetric Supercapacitors Based on Vertically Aligned CuSe@Co(OH) 2 Nanosheet Arrays

DOE PAGES

Gong, Jiangfeng; Tian, Yazhou; Yang, Ziyuan; ...

2018-01-04

The developments of electrode active materials provide the opportunities for next-generation energy storage devices. The arrangement of electrode materials on the substrate has recently emerged as a promising strategy for preparing high-performance supercapacitors. In this paper, we demonstrate a novel vertically aligned CuSe@Co(OH) 2 nanosheet arrays electrode for supercapacitor application. The materials are thoroughly characterized by structural and spectroscopic techniques. Electrochemical performance of CuSe@Co(OH) 2 nanosheet arrays are investigated in detail, which exhibit a specific capacitance as much as 1180 F g -1 at a current density of 1 A g -1. A flexible asymmetric all-solid-state supercapacitor is fabricated usingmore » CuSe@Co(OH) 2 nanosheet arrays as the positive electrode and activated carbon as the negative electrode. The device delivers a volumetric capacitance of 441.4 mF cm -3 with maximum energy density and maximum power density is 0.17 and 62.1 mW cm -3, as well as robust cycling stability (~80.4% capacitance retention after 10 000 cycles), excellent flexibility, and mechanical stability. Finally, the excellent electrochemical performance can be attributed to its unique vertically aligned configuration.« less

A PDMS-Based Conical-Well Microelectrode Array for Surface Stimulation and Recording of Neural Tissues

PubMed Central

Guo, Liang; Meacham, Kathleen W.; Hochman, Shawn

2012-01-01

A method for fabricating polydimethylsiloxane (PDMS)-based microelectrode arrays (MEAs) featuring novel conical-well microelectrodes is described. The fabrication technique is reliable and efficient, and facilitates controllability over both the depth and the slope of the conical wells. Because of the high PDMS elasticity (as compared to other MEA substrate materials), this type of compliant MEA is promising for acute and chronic implantation in applications that benefit from conformable device contact with biological tissue surfaces and from minimal tissue damage. The primary advantage of the conical-well microelectrodes—when compared to planar electrodes—is that they provide an improved contact on tissue surface, which potentially provides isolation of the electrode microenvironment for better electrical interfacing. The raised wells increase the uniformity of current density distributions at both the electrode and tissue surfaces, and they also protect the electrode material from mechanical damage (e.g. from rubbing against the tissue). Using this technique, electrodes have been fabricated with diameters as small as 10µm and arrays have been fabricated with center-to-center electrode spacings of 60µm. Experimental results are presented, describing electrode-profile characterization, electrode-impedance measurement, and MEA-performance evaluation on fiber bundle recruitment in spinal cord white matter. PMID:20550983

Electronic Tongue for Quantitation of Contaminants in Water

NASA Technical Reports Server (NTRS)

Buehler, Marlin; Kuhlman, Gregory

2004-01-01

An assembly of sensors, denoted an electronic tongue, is undergoing development as a prototype of compact devices for use in measuring concentrations of contaminants in water. Thus far, the electronic tongue has been tested on ions of Cu, Zn, Pb, and Fe and shown to respond to concentrations as low as about 10 parts per million. This electronic tongue is expected to be capable of measuring concentrations of other metal ions and organic compounds. Potential uses for electronic tongues include monitoring the chemical quality of water in a variety of natural, industrial, and laboratory settings; detecting micro-organisms indirectly by measuring microbially influenced corrosion; and characterizing compounds of interest to the pharmaceutical and food industries. This version of the electronic tongue includes a heater, a temperature sensor, an array of ion-specific electrodes, an oxidation/ reduction sensor pair, an electrical-conductivity sensor, and an array of galvanic cells, all on one compact ceramic substrate. Special-purpose electronic excitation and readout circuitry for the sensors has also been constructed. The main advantage of the electronic tongue, relative to electrodes of this type used traditionally to assess water quality, is extreme ruggedness. The types of measurements that can be performed by use of the sensors on the electronic tongue are quite varied. The best combination of types of measurements for a given application depends on the specific contaminants that one seeks to detect. Experimental studies to identify such combinations were in progress at the time of reporting the information for this article.

A flexible electrode array for muscle impedance measurements in the mouse hind limb: A tool to speed research in neuromuscular disease

NASA Astrophysics Data System (ADS)

Li, J.; Rutkove, S. B.

2013-04-01

Electrical impedance myography (EIM) is a bioelectrical impedance technique focused on the assessment of neuromuscular diseases using tetrapolar surface arrays. Recently, we have shown that reproducible and sensitive EIM measurements can be made on the gastrocnemius muscle of the mouse hind limb and that these are sensitive to disease alterations. A dedicated array would help speed data acquisition and provide additional sensitivity to disease-induced alterations. A flexible electrode array was developed with electrode sizes of 1mm × 1mm by Parlex, Inc. Tetrapolar electrode sets were arranged both parallel to (longitudinal) and orthogonally to (transverse) the major muscle fiber direction of the gastrocnemius muscle. Measurements were made with a dedicated EIM system. A total of 11 healthy animals and 7 animals with spinal muscular atrophy (a form of motor neuron disease) were evaluated after the fur was completely removed with a depilatory agent from the hind limb. Standard electrophysiologic testing (compound motor action potential amplitude and motor unit number estimation) was also performed. The flexible electrode array demonstrated high repeatability in both the longitudinal and transverse directions in the healthy and diseased animals (with intraclass correlation coefficients of 0.94 and 0.89, respectively, for phase angle measured transversely). In addition, differences between healthy and diseased animals were identifiable. For example, the 50 kHz transverse phase angle was higher in the healthy as compared to the SMA animals (16.8° ± 0.5 vs. 14.3° ± 0.7, respectively) at 21 weeks of age (p = 0.01). Differences in anisotropy were also identifiable. Correlations to several standard neurophysiologic parameters also appeared promising. This novel flexible tetrapolar electrode array can be used on the mouse hind limb and provides multidirectional data that can be used to assess muscle health. This technique has the potential of finding widespread use in the evaluation of drug therapies in neuromuscular animal disease models.

Optimal Micro-Vane Flow Control for Compact Air Vehicle Inlets

NASA Technical Reports Server (NTRS)

Anderson, Bernhard H.; Miller, Daniel N.; Addington, Gregory A.; Agrell, Johan

2004-01-01

The purpose of this study on micro-vane secondary flow control is to demonstrate the viability and economy of Response Surface Methodology (RSM) to optimally design micro-vane secondary flow control arrays, and to establish that the aeromechanical effects of engine face distortion can also be included in the design and optimization process. These statistical design concepts were used to investigate the design characteristics of "low unit strength" micro-effector arrays. "Low unit strength" micro-effectors are micro-vanes set at very low angles-of-incidence with very long chord lengths. They were designed to influence the near wall inlet flow over an extended streamwise distance, and their advantage lies in low total pressure loss and high effectiveness in managing engine face distortion. Therefore, this report examines optimal micro-vane secondary flow control array designs for compact inlets through a Response Surface Methodology.

Dielectrophoretic immobilisation of nanoparticles as isolated singles in regular arrays

NASA Astrophysics Data System (ADS)

Knigge, Xenia; Wenger, Christian; Bier, Frank F.; Hölzel, Ralph

2018-02-01

We demonstrate the immobilisation of polystyrene nanoparticles on vertical nano-electrodes by means of dielectrophoresis. The electrodes have diameters of 500 nm or 50 nm, respectively, and are arranged in arrays of several thousand electrodes, allowing many thousands of experiments in parallel. At a frequency of 15 kHz, which is found favourable for polystyrene, several occupation patterns are observed, and both temporary and permanent immobilisation is achieved. In addition, a histogram method is applied, which allows to determine the number of particles occupying the electrodes. These results are validated with scanning electron microscopy images. Immobilising exactly one particle at each electrode tip is achieved for electrode tip diameters with half the particle size. Extension of this system down to the level of single molecules is envisaged, which will avoid ensemble averaging at still statistically large sample sizes.

Hierarchical mesoporous nickel cobaltite nanoneedle/carbon cloth arrays as superior flexible electrodes for supercapacitors

PubMed Central

2014-01-01

Hierarchical mesoporous NiCo2O4 nanoneedle arrays on carbon cloth have been fabricated by a simple hydrothermal approach combined with a post-annealing treatment. Such unique array nanoarchitectures exhibit remarkable electrochemical performance with high capacitance and desirable cycle life at high rates. When evaluated as an electrode material for supercapacitors, the NiCo2O4 nanoneedle arrays supported on carbon cloth was able to deliver high specific capacitance of 660 F g-1 at current densities of 2 A g-1 in 2 M KOH aqueous solution. In addition, the composite electrode shows excellent mechanical behavior and long-term cyclic stability (91.8% capacitance retention after 3,000 cycles). The fabrication method presented here is facile, cost-effective, and scalable, which may open a new pathway for real device applications. PMID:24661431

Adaptive microlens array based on electrically charged polyvinyl chloride/dibutyl phthalate gel

NASA Astrophysics Data System (ADS)

Xu, Miao; Ren, Hongwen

2016-09-01

We prepared an adaptive microlens array (MLA) using a polyvinyl chloride/dibutyl phthalate gel and an indium-tin-oxide (ITO) glass substrate. The gel forms a membrane on the glass substrate and the ITO electrode has a ring array pattern. When the membrane is electrically charged by a DC voltage, the surface of the membrane above each circular electrode in the ring array can be deformed with a convex shape. As a result, the membrane functions as an MLA. By applying a voltage from 20 to ˜65 V to the electrode, the focal length of each microlens can be tuned from 300 to ˜160 μm. The dynamic response time can by reduced largely by changing the polarity of the DC voltage. Due to the advantages of optical isotropy, compact structure, and good stability, our MLA has potential applications in imaging, biometrics, and electronic displays.

P(VDF-TrFE) ferroelectric nanotube array for high energy density capacitor applications.

PubMed

Li, Xue; Lim, Yee-Fun; Yao, Kui; Tay, Francis Eng Hock; Seah, Kar Heng

2013-01-14

Poly(vinylidene-fluoride-co-trifluoroethylene) (P(VDF-TrFE)) ferroelectric nanotube arrays were fabricated using an anodized alumina membrane (AAM) as a template and silver electrodes were deposited on both the outer and inner sides of the nanotubes by an electroless plating method. The nanotubes have the unique structure of being sealed at one end and linked at the open end, thus preventing electrical shorting between the inner and outer electrodes. Compared with a P(VDF-TrFE) film with a similar overall thickness, the idealized nanotube array has a theoretical capacitance that is 763 times larger due to the greatly enlarged contact area between the electrodes and the polymer dielectric. A capacitance that is 95 times larger has been demonstrated experimentally, thus indicating that such nanotube arrays are promising for realizing high density capacitance and high power dielectric energy storage.

Simple and Fast Method for Fabrication of Endoscopic Implantable Sensor Arrays

PubMed Central

Tahirbegi, I. Bogachan; Alvira, Margarita; Mir, Mònica; Samitier, Josep

2014-01-01

Here we have developed a simple method for the fabrication of disposable implantable all-solid-state ion-selective electrodes (ISE) in an array format without using complex fabrication equipment or clean room facilities. The electrodes were designed in a needle shape instead of planar electrodes for a full contact with the tissue. The needle-shape platform comprises 12 metallic pins which were functionalized with conductive inks and ISE membranes. The modified microelectrodes were characterized with cyclic voltammetry, scanning electron microscope (SEM), and optical interferometry. The surface area and roughness factor of each microelectrode were determined and reproducible values were obtained for all the microelectrodes on the array. In this work, the microelectrodes were modified with membranes for the detection of pH and nitrate ions to prove the reliability of the fabricated sensor array platform adapted to an endoscope. PMID:24971473

Integrated TiN coated porous silicon supercapacitor with large capacitance per foot print

NASA Astrophysics Data System (ADS)

Grigoras, Kestutis; Grönberg, Leif; Ahopelto, Jouni; Prunnila, Mika

2017-05-01

We have fabricated a micro-supercapacitor with porous silicon electrodes coated with TiN by atomic layer deposition technique. The coating provides an efficient surface passivation and high electrical conductivity of the electrodes, resulting in stable and almost ideal electrochemical double layer capacitor behavior with characteristics comparable to the best carbon based micro-supercapacitors. Stability of the supercapacitor is verified by performing 50 000 voltammetry cycles with high capacitance retention obtained. Silicon microfabrication techniques facilitate integration of both supercapacitor electrodes inside the silicon substrate and, in this work, such in-chip supercapacitor is demonstrated. This approach allows realization of very high capacitance per foot print area. The in-chip micro-supercapacitor can be integrated with energy harvesting elements and can be used in wearable and implantable microdevices.

Batch-processed semiconductor gas sensor array for the selective detection of NOx in automotive exhaust gas

NASA Astrophysics Data System (ADS)

Jang, Hani; Kim, Minki; Kim, Yongjun

2016-12-01

This paper reports on a semiconductor gas sensor array to detect nitrogen oxides (NOx) in automotive exhaust gas. The proposed semiconductor gas sensor array consisted of one common electrode and three individual electrodes to minimize the size of the sensor array, and three sensing layers [TiO2 + SnO2 (15 wt%), SnO2, and Ga2O3] were deposited using screen printing. In addition, sensing materials were sintered under the same conditions in order to take advantage of batch processing. The sensing properties of the proposed sensor array were verified by experimental measurements, and the selectivity improved by using pattern recognition.

Vertically aligned ZnO nanorod core-polypyrrole conducting polymer sheath and nanotube arrays for electrochemical supercapacitor energy storage

PubMed Central

2014-01-01

Nanocomposite electrodes having three-dimensional (3-D) nanoscale architecture comprising of vertically aligned ZnO nanorod array core-polypyrrole (PPy) conducting polymer sheath and the vertical PPy nanotube arrays have been investigated for supercapacitor energy storage. The electrodes in the ZnO nanorod core-PPy sheath structure are formed by preferential nucleation and deposition of PPy layer over hydrothermally synthesized vertical ZnO nanorod array by controlled pulsed current electropolymerization of pyrrole monomer under surfactant action. The vertical PPy nanotube arrays of different tube diameter are created by selective etching of the ZnO nanorod core in ammonia solution for different periods. Cyclic voltammetry studies show high areal-specific capacitance approximately 240 mF.cm-2 for open pore and approximately 180 mF.cm-2 for narrow 30-to-36-nm diameter PPy nanotube arrays attributed to intensive faradic processes arising from enhanced access of electrolyte ions through nanotube interior and exterior. Impedance spectroscopy studies show that capacitive response extends over larger frequency domain in electrodes with PPy nanotube structure. Simulation of Nyquist plots by electrical equivalent circuit modeling establishes that 3-D nanostructure is better represented by constant phase element which accounts for the inhomogeneous electrochemical redox processes. Charge-discharge studies at different current densities establish that kinetics of the redox process in PPy nanotube electrode is due to the limitation on electron transport rather than the diffusive process of electrolyte ions. The PPy nanotube electrodes show deep discharge capability with high coulomb efficiency and long-term charge-discharge cyclic studies show nondegrading performance of the specific areal capacitance tested for 5,000 cycles. PMID:25246867

Field ion source development for neutron generators

NASA Astrophysics Data System (ADS)

Bargsten Johnson, B.; Schwoebel, P. R.; Holland, C. E.; Resnick, P. J.; Hertz, K. L.; Chichester, D. L.

2012-01-01

An ion source based on the principles of electrostatic field desorption is being developed to improve the performance of existing compact neutron generators. The ion source is an array of gated metal tips derived from field electron emitter array microfabrication technology. A comprehensive summary of development and experimental activities is presented. Many structural modifications to the arrays have been incorporated to achieve higher tip operating fields, while lowering fields at the gate electrode to prevent gate field electron emission which initiates electrical breakdown in the array. The latest focus of fabrication activities has been on rounding the gate electrode edge and surrounding the gate electrode with dielectric material. Array testing results have indicated a steady progression of increased array tip operating fields with each new design tested. The latest arrays have consistently achieved fields beyond those required for the onset of deuterium desorption (˜20 V/nm), and have demonstrated the desorption of deuterium at fields up to 36 V/nm. The number of ions desorbed from an array has been quantified, and field desorption of metal tip substrate material from array tips has been observed for the first time. Gas-phase field ionization studies with ˜10,000 tip arrays have achieved deuterium ion currents of ˜50 nA. Neutron production by field ionization has yielded ˜10 2 n/s from ˜1 mm 2 of array area using the deuterium-deuterium fusion reaction at 90 kV.

Development of CE-dual opposite carbon-fiber micro-disk electrode detection for peak purity assessment of polyphenols in red wine.

PubMed

Du, Fuying; Fung, Ying Sing

2010-07-01

A new dual opposite carbon-fiber micro-disk electrode detector was fabricated and tested for hyphenation with CE in the polyphenol determination. Under optimized conditions, CE-dual opposite carbon-fiber micro-disk electrode was found able to baseline separate and determine five important polyphenols (trans-resveratrol, (+)-catechin, (-)-epicatechin, quercetin and gallic acid) in red wine within 16 min with low detection limit (0.031-0.21 mg/L) and satisfactory repeatability (2.0-3.3% RSD, n=5). The opposite dual electrode enables simultaneous determination of CE eluents for current ratio measured at +0.8 and +1.0 V versus Ag/AgCl for the peak purity assessment. The capability to identify the presence of co-migrating impurities in given polyphenol peaks was demonstrated in a mixed standard solution with overlapping (+)-catechin and (-)-epicatechin peaks and in commercial red wine with unknown impurities and confirming the reliability for polyphenol quantitation in red wine with matching migration time and current ratio.

Fabrication of a sensing module using micromachined biosensors.

PubMed

Suzuki, H; Arakawa, H; Karube, I

2001-12-01

Micromachining is a powerful tool in constructing micro biosensors and micro systems which incorporate them. A sensing module for blood components was fabricated using the technology. The analytes include glucose, urea, uric acid, creatine, and creatinine. Transducers used to construct the corresponding sensors were a Severinghaus-type carbon dioxide electrode for the urea sensor and a Clark-type oxygen electrode for the other analytes. In these electrodes, detecting electrode patterns were formed on a glass substrate by photolithography and the micro container for the internal electrolyte solution was formed on a silicon substrate by anisotropic etching. A through-hole was formed in the sensitive area, where a silicone gas-permeable membrane was formed and an enzyme was immobilized. The sensors were characterized in terms of pH and temperature dependence and calibration curves along with detection limits. Furthermore, the sensors were incorporated in an acrylate flow cell. Simultaneous operation of these sensors was successfully conducted and distinct and stable responses were observed for respective sensors.

Titanium nitride films for micro-supercapacitors: Effect of surface chemistry and film morphology on the capacitance

NASA Astrophysics Data System (ADS)

Achour, Amine; Porto, Raul Lucio; Soussou, Mohamed-Akram; Islam, Mohammad; Boujtita, Mohammed; Aissa, Kaltouma Ait; Le Brizoual, Laurent; Djouadi, Abdou; Brousse, Thierry

2015-12-01

Electrochemical capacitors (EC) in the form of packed films can be integrated in various electronic devices as power source. A fabrication process of EC electrodes, which is compatible with micro-fabrication, should be addressed for practical applications. Here, we show that titanium nitride films with controlled porosity can be deposited on flat silicon substrates by reactive DC-sputtering for use as high performance micro-supercapacitor electrodes. A superior volumetric capacitance as high as 146.4 F cm-3, with an outstanding cycling stability over 20,000 cycles, was measured in mild neutral electrolyte of potassium sulfate. The specific capacitance of the films as well as their capacitance retentions were found to depend on thickness, porosity and surface chemistry of electrodes. The one step process used to fabricate these TiN electrodes and the wide use of this material in the field of semiconductor technology make it promising for miniaturized energy storage systems.

Electrostatic quadrupole array for focusing parallel beams of charged particles

DOEpatents

Brodowski, John

1982-11-23

An array of electrostatic quadrupoles, capable of providing strong electrostatic focusing simultaneously on multiple beams, is easily fabricated from a single array element comprising a support rod and multiple electrodes spaced at intervals along the rod. The rods are secured to four terminals which are isolated by only four insulators. This structure requires bias voltage to be supplied to only two terminals and eliminates the need for individual electrode bias and insulators, as well as increases life by eliminating beam plating of insulators.

Dielectrophoresis device and method having non-uniform arrays for manipulating particles

DOEpatents

Cummings, Eric B [Livermore, CA; Fintschenko, Yolanda [Livermore, CA; Simmons, Blake [San Francisco, CA

2008-09-02

Microfluidic devices according to embodiments of the present invention include an inlet port, an outlet port, and a channel or chamber having a non-uniform array of insulating features on one or more surfaces. Electrodes are provided for generation of a spatially non-uniform electric field across the array. A voltage source, which may be an A.C. and/or a D.C. voltage source may be coupled to the electrodes for the generation of the electric field.

Dielectrophoresis device and method having nonuniform arrays for manipulating particles

DOEpatents

Cummings, Eric B.; Fintschenko, Yolanda; Simmons, Blake A.

2012-09-04

Microfluidic devices according to embodiments of the present invention include an inlet port, an outlet port, and a channel or chamber having a non-uniform array of insulating features on one or more surfaces. Electrodes are provided for generation of a spatially non-uniform electric field across the array. A voltage source, which may be an A.C. and/or a D.C. voltage source may be coupled to the electrodes for the generation of the electric field.

Electrokinetically driven active micro-mixers utilizing zeta potential variation induced by field effect

NASA Astrophysics Data System (ADS)

Lee, Chia-Yen; Lee, Gwo-Bin; Fu, Lung-Ming; Lee, Kuo-Hoong; Yang, Ruey-Jen

2004-10-01

This paper presents a new electrokinetically driven active micro-mixer which uses localized capacitance effects to induce zeta potential variations along the surface of silica-based microchannels. The mixer is fabricated by etching bulk flow and shielding electrode channels into glass substrates and then depositing Au/Cr thin films within the latter to form capacitor electrodes, which establish localized zeta potential variations near the electrical double layer (EDL) region of the electroosmotic flow (EOF) within the microchannels. The potential variations induce flow velocity changes within a homogeneous fluid and a rapid mixing effect if an alternating electric field is provided. The current experimental data confirm that the fluid velocity can be actively controlled by using the capacitance effect of the buried shielding electrodes to vary the zeta potential along the channel walls. While compared with commonly used planar electrodes across the microchannels, the buried shielding electrodes prevent current leakage caused by bad bonding and allow direct optical observation during operation. It also shows that the buried shielding electrodes can significantly induce the field effect, resulting in higher variations of zeta potential. Computational fluid dynamic simulations are also used to study the fluid characteristics of the developed active mixers. The numerical and experimental results demonstrate that the developed microfluidic device permits a high degree of control over the fluid flow and an efficient mixing effect. Moreover, the developed device could be used as a pumping device as well. The development of the active electrokinetically driven micro-mixer could be crucial for micro-total-analysis-systems.

Effects of process parameters on the molding quality of the micro-needle array

NASA Astrophysics Data System (ADS)

Qiu, Z. J.; Ma, Z.; Gao, S.

2016-07-01

Micro-needle array, which is used in medical applications, is a kind of typical injection molded products with microstructures. Due to its tiny micro-features size and high aspect ratios, it is more likely to produce short shots defects, leading to poor molding quality. The injection molding process of the micro-needle array was studied in this paper to find the effects of the process parameters on the molding quality of the micro-needle array and to provide theoretical guidance for practical production of high-quality products. With the shrinkage ratio and warpage of micro needles as the evaluation indices of the molding quality, the orthogonal experiment was conducted and the analysis of variance was carried out. According to the results, the contribution rates were calculated to determine the influence of various process parameters on molding quality. The single parameter method was used to analyse the main process parameter. It was found that the contribution rate of the holding pressure on shrinkage ratio and warpage reached 83.55% and 94.71% respectively, far higher than that of the other parameters. The study revealed that the holding pressure is the main factor which affects the molding quality of micro-needle array so that it should be focused on in order to obtain plastic parts with high quality in the practical production.

Selective stimulation of facial muscles with a penetrating electrode array in the feline model

PubMed Central

Sahyouni, Ronald; Bhatt, Jay; Djalilian, Hamid R.; Tang, William C.; Middlebrooks, John C.; Lin, Harrison W.

2017-01-01

Objective Permanent facial nerve injury is a difficult challenge for both patients and physicians given its potential for debilitating functional, cosmetic, and psychological sequelae. Although current surgical interventions have provided considerable advancements in facial nerve rehabilitation, they often fail to fully address all impairments. We aim to introduce an alternative approach to facial nerve rehabilitation. Study design Acute experiments in animals with normal facial function. Methods The study included three anesthetized cats. Four facial muscles (levator auris longus, orbicularis oculi, nasalis, and orbicularis oris) were monitored with a standard electromyographic (EMG) facial nerve monitoring system with needle electrodes. The main trunk of the facial nerve was exposed and a 16-channel penetrating electrode array was placed into the nerve. Electrical current pulses were delivered to each stimulating electrode individually. Elicited EMG voltage outputs were recorded for each muscle. Results Stimulation through individual channels selectively activated restricted nerve populations, resulting in selective contraction of individual muscles. Increasing stimulation current levels resulted in increasing EMG voltage responses. Typically, selective activation of two or more distinct muscles was successfully achieved via a single placement of the multi-channel electrode array by selection of appropriate stimulation channels. Conclusion We have established in the animal model the ability of a penetrating electrode array to selectively stimulate restricted fiber populations within the facial nerve and to selectively elicit contractions in specific muscles and regions of the face. These results show promise for the development of a facial nerve implant system. PMID:27312936

Effects of Nanowire Length and Surface Roughness on the Electrochemical Sensor Properties of Nafion-Free, Vertically Aligned Pt Nanowire Array Electrodes

PubMed Central

Li, Zhiyang; Leung, Calvin; Gao, Fan; Gu, Zhiyong

2015-01-01

In this paper, vertically aligned Pt nanowire arrays (PtNWA) with different lengths and surface roughnesses were fabricated and their electrochemical performance toward hydrogen peroxide (H2O2) detection was studied. The nanowire arrays were synthesized by electroplating Pt in nanopores of anodic aluminum oxide (AAO) template. Different parameters, such as current density and deposition time, were precisely controlled to synthesize nanowires with different surface roughnesses and various lengths from 3 μm to 12 μm. The PtNWA electrodes showed better performance than the conventional electrodes modified by Pt nanowires randomly dispersed on the electrode surface. The results indicate that both the length and surface roughness can affect the sensing performance of vertically aligned Pt nanowire array electrodes. Generally, longer nanowires with rougher surfaces showed better electrochemical sensing performance. The 12 μm rough surface PtNWA presented the largest sensitivity (654 μA·mM−1·cm−2) among all the nanowires studied, and showed a limit of detection of 2.4 μM. The 12 μm rough surface PtNWA electrode also showed good anti-interference property from chemicals that are typically present in the biological samples such as ascorbic, uric acid, citric acid, and glucose. The sensing performance in real samples (river water) was tested and good recovery was observed. These Nafion-free, vertically aligned Pt nanowires with surface roughness control show great promise as versatile electrochemical sensors and biosensors. PMID:26404303

Surgical factors in pediatric cochlear implantation and their early effects on electrode activation and functional outcomes.

PubMed

Francis, Howard W; Buchman, Craig A; Visaya, Jiovani M; Wang, Nae-Yuh; Zwolan, Teresa A; Fink, Nancy E; Niparko, John K

2008-06-01

To assess the impact of surgical factors on electrode status and early communication outcomes in young children in the first 2 years of cochlear implantation. Prospective multicenter cohort study. Six tertiary referral centers. Children 5 years or younger before implantation with normal nonverbal intelligence. Cochlear implant operations in 209 ears of 188 children. Percent active channels, auditory behavior as measured by the Infant Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale and Reynell receptive language scores. Stable insertion of the full electrode array was accomplished in 96.2% of ears. At least 75% of electrode channels were active in 88% of ears. Electrode deactivation had a significant negative effect on Infant Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale scores at 24 months but no effect on receptive language scores. Significantly fewer active electrodes were associated with a history of meningitis. Surgical complications requiring additional hospitalization and/or revision surgery occurred in 6.7% of patients but had no measurable effect on the development of auditory behavior within the first 2 years. Negative, although insignificant, associations were observed between the need for perioperative revision of the device and 1) the percent of active electrodes and 2) the receptive language level at 2-year follow-up. Activation of the entire electrode array is associated with better early auditory outcomes. Decrements in the number of active electrodes and lower gains of receptive language after manipulation of the newly implanted device were not statistically significant but may be clinically relevant, underscoring the importance of surgical technique and the effective placement of the electrode array.

Depositing bulk or micro-scale electrodes

DOEpatents

Shah, Kedar G.; Pannu, Satinderpall S.; Tolosa, Vanessa; Tooker, Angela C.; Sheth, Heeral J.; Felix, Sarah H.; Delima, Terri L.

2016-11-01

Thicker electrodes are provided on microelectronic device using thermo-compression bonding. A thin-film electrical conducting layer forms electrical conduits and bulk depositing provides an electrode layer on the thin-film electrical conducting layer. An insulating polymer layer encapsulates the electrically thin-film electrical conducting layer and the electrode layer. Some of the insulating layer is removed to expose the electrode layer.

Manipulation and Investigation of Uniformly-Spaced Nanowire Array on a Substrate via Dielectrophoresis and Electrostatic Interaction.

PubMed

Choi, U Hyeok; Park, Ji Hun; Kim, Jaekyun

2018-06-21

Directed-assembly of nanowires on the dielectrics-covered parallel electrode structure is capable of producing uniformly-spaced nanowire array at the electrode gap due to dielectrophoretic nanowire attraction and electrostatic nanowire repulsion. Beyond uniformly-spaced nanowire array formation, the control of spacing in the array is beneficial in that it should be the experimental basis of the precise positioning of functional nanowires on a circuit. Here, we investigate the material parameters and bias conditions to modulate the nanowire spacing in the ordered array, where the nanowire array formation is readily attained due to the electrostatic nanowire interaction. A theoretical model for the force calculation and the simulation of the induced charge in the assembled nanowire verifies that the longer nanowires on thicker dielectric layer tend to be assembled with a larger pitch due to the stronger nanowire-nanowire electrostatic repulsion, which is consistent with the experimental results. It was claimed that the stronger dielectrophoretic force is likely to attract more nanowires that are suspended in solution at the electrode gap, causing them to be less-spaced. Thus, we propose a generic mechanism, competition of dielectrophoretic and electrostatic force, to determine the nanowire pitch in an ordered array. Furthermore, this spacing-controlled nanowire array offers a way to fabricate the high-density nanodevice array without nanowire registration.

Morphologies and optical and electrical properties of InGaN/GaN micro-square array light-emitting diode chips.

PubMed

Han, Dan; Ma, Shufang; Jia, Zhigang; Liu, Peizhi; Jia, Wei; Shang, Lin; Zhai, Guangmei; Xu, Bingshe

2018-04-10

InGaN/GaN micro-square array light-emitting diode (LED) chips (micro-chips) have been prepared via the focused ion beam (FIB) etching technique, which can not only reduce ohmic contact degradation but also control the aspect ratio precisely in three-dimensional (3D) structure LED (3D-LED) device fabrication. The effects of FIB beam current and micro-square array depth on morphologies and optical and electrical properties of the micro-chips have been studied. Our results show that sidewall surface morphology and optical and electrical properties of the micro-chips degrade with increased beam current. After potassium hydroxide etching with different times, an optimal current-voltage and luminescence performance can be obtained. Combining the results of cathodoluminescence mappings and light output-current characteristics, the light extraction efficiency of the micro-chips is reduced as FIB etch depth increases. The mechanisms of micro-square depth on light extraction have been revealed by 3D finite difference time domain.

Processing soft materials for integrated photonic and macroelectronic components and devices

NASA Astrophysics Data System (ADS)

Tsay, Candice Ruth

Incorporating soft materials into micro-fabrication processes opens up new functionalities for fabricated devices, but requires unique processing routes. This thesis presents our development of integrated photonic and macroelectronic structures through processing innovations that unite disparate inorganic/organic, and soft/rigid materials systems. For the integrated photonic system, we focus our efforts on chalcogenide glasses, dielectric materials that exhibit a variety of optical properties that make them desirable for near- and mid-infrared communications and sensing applications. However, processing limitations for these relatively fragile materials have made the direct integration of waveguides with sources or detectors challenging. Here we demonstrate the viability of several additive methods for patterning chalcogenide glass waveguides from solution. In particular, we focus on two complementary soft lithography methods. The first, micro-molding in capillaries (MIMIC), is shown to fabricate multi-mode As2S 3 waveguides which are directly integrated with quantum cascade lasers (QCLs). In a second method, we demonstrate the ability of micro-transfer molding (muTM), to produce arrays of single mode rib waveguides over large areas while maintaining low surface and edge roughness. These methods form a suite of processes that can be applied to chalcogenide solutions to create a diverse array of mid-IR photonic structures ranging from less than 5 to 10's of mum in cross-sectional dimension. Optical characterization, including measurement of waveguide loss by cut-back, is carried out in the mid-IR using QCLs. In addition, materials characterization of the chalcogenide glass structures is carried out to determine loss mechanisms and optimize processing. While we use soft polymeric materials as molds to pattern chalcogenide glasses, we also employ them as substrate material for stretchable electronic systems, which comprise a new class of flexible macroelectronics. These devices must undergo elastic deformation to large strain (>10%), for applications in which electronics are conformally shaped around surfaces of arbitrary shape, like many biological surfaces. We develop strategies for processing stretchable metallic electrodes and study the mechanism of their stretchability via careful observation of thin film micro-structures. Our macroelectronic work culminates in fabrication of stretchable microelectrode arrays that interface with brain tissue, laying the groundwork for future development of advanced bio-electronic interfaces.

Fabrication of nickel hydroxide electrodes with open-ended hexagonal nanotube arrays for high capacitance supercapacitors.

PubMed

Wu, Mao-Sung; Huang, Kuo-Chih

2011-11-28

A nickel hydroxide electrode with open-ended hexagonal nanotube arrays, prepared by hydrolysis of nickel chloride in the presence of hexagonal ZnO nanorods, shows a very high capacitance of 1328 F g(-1) at a discharge current density of 1 A g(-1) due to the significantly improved ion transport.

Integrated field emission array for ion desorption

DOEpatents

Resnick, Paul J; Hertz, Kristin L.; Holland, Christopher; Chichester, David

2016-08-23

An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

Integrated field emission array for ion desorption

DOEpatents

Resnick, Paul J; Hertz, Kristin L; Holland, Christopher; Chichester, David; Schwoebel, Paul

2013-09-17

An integrated field emission array for ion desorption includes an electrically conductive substrate; a dielectric layer lying over the electrically conductive substrate comprising a plurality of laterally separated cavities extending through the dielectric layer; a like plurality of conically-shaped emitter tips on posts, each emitter tip/post disposed concentrically within a laterally separated cavity and electrically contacting the substrate; and a gate electrode structure lying over the dielectric layer, including a like plurality of circular gate apertures, each gate aperture disposed concentrically above an emitter tip/post to provide a like plurality of annular gate electrodes and wherein the lower edge of each annular gate electrode proximate the like emitter tip/post is rounded. Also disclosed herein are methods for fabricating an integrated field emission array.

Electrogenerated Chemiluminescence of BODIPY, Ru(bpy)32+, and 9,10-Diphenylanthracene Using Interdigitated Array Electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nepomnyashchii, Alexander B.; Kolesov, Grigory; Parkinson, Bruce A.

Interdigitated array electrodes (IDAs) were used to produce steady-state electrogenerated chemiluminescence (ECL) by annihilation of oxidized and reduced forms of a substituted boron dipyrromethene (BODIPY) dye, 9,10-diphenylanthracene (DPA), and ruthenium(II) tris(bypiridine) (Ru-(bpy)32+). Digital simulations were in good agreement with the experimentally obtained currents and light outputs. Coreactant experiments, using tri-n-propylamine and benzoyl peroxide as a sacrificial homogeneous reductant or oxidant, show currents corresponding to electrode reactions of the dyes and not the oxidation or reduction of the coreactants. The results show that interdigitated arrays can produce stable ECL where the light intensity is magnified due to the larger currents asmore » a consequence of feedback between generator and collector electrodes in the IDA. The light output for ECL is around 100 times higher than that obtained with regular planar electrodes with similar area. This material is based upon work supported as part of the Center of Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.« less

Electrical stimulus artifact cancellation and neural spike detection on large multi-electrode arrays

PubMed Central

Grosberg, Lauren E.; Madugula, Sasidhar; Litke, Alan; Cunningham, John; Chichilnisky, E. J.; Paninski, Liam

2017-01-01

Simultaneous electrical stimulation and recording using multi-electrode arrays can provide a valuable technique for studying circuit connectivity and engineering neural interfaces. However, interpreting these measurements is challenging because the spike sorting process (identifying and segregating action potentials arising from different neurons) is greatly complicated by electrical stimulation artifacts across the array, which can exhibit complex and nonlinear waveforms, and overlap temporarily with evoked spikes. Here we develop a scalable algorithm based on a structured Gaussian Process model to estimate the artifact and identify evoked spikes. The effectiveness of our methods is demonstrated in both real and simulated 512-electrode recordings in the peripheral primate retina with single-electrode and several types of multi-electrode stimulation. We establish small error rates in the identification of evoked spikes, with a computational complexity that is compatible with real-time data analysis. This technology may be helpful in the design of future high-resolution sensory prostheses based on tailored stimulation (e.g., retinal prostheses), and for closed-loop neural stimulation at a much larger scale than currently possible. PMID:29131818

All Inkjet-Printed Amperometric Multiplexed Biosensors Based on Nanostructured Conductive Hydrogel Electrodes.

PubMed

Li, Lanlan; Pan, Lijia; Ma, Zhong; Yan, Ke; Cheng, Wen; Shi, Yi; Yu, Guihua

2018-06-13

Multiplexing, one of the main trends in biosensors, aims to detect several analytes simultaneously by integrating miniature sensors on a chip. However, precisely depositing electrode materials and selective enzymes on distinct microelectrode arrays remains an obstacle to massively produced multiplexed sensors. Here, we report on a "drop-on-demand" inkjet printing process to fabricate multiplexed biosensors based on nanostructured conductive hydrogels in which the electrode material and several kinds of enzymes were printed on the electrode arrays one by one by employing a multinozzle inkjet system. The whole inkjet printing process can be finished within three rounds of printing and only one round of alignment. For a page of sensor arrays containing 96 working electrodes, the printing process took merely ∼5 min. The multiplexed assays can detect glucose, lactate, and triglycerides in real time with good selectivity and high sensitivity, and the results in phosphate buffer solutions and calibration serum samples are comparable. The inkjet printing process exhibited advantages of high efficiency and accuracy, which opens substantial possibilities for massive fabrication of integrated multiplexed biosensors for human health monitoring.

Method of fabrication of display pixels driven by silicon thin film transistors

DOEpatents

Carey, Paul G.; Smith, Patrick M.

1999-01-01

Display pixels driven by silicon thin film transistors are fabricated on plastic substrates for use in active matrix displays, such as flat panel displays. The process for forming the pixels involves a prior method for forming individual silicon thin film transistors on low-temperature plastic substrates. Low-temperature substrates are generally considered as being incapable of withstanding sustained processing temperatures greater than about 200.degree. C. The pixel formation process results in a complete pixel and active matrix pixel array. A pixel (or picture element) in an active matrix display consists of a silicon thin film transistor (TFT) and a large electrode, which may control a liquid crystal light valve, an emissive material (such as a light emitting diode or LED), or some other light emitting or attenuating material. The pixels can be connected in arrays wherein rows of pixels contain common gate electrodes and columns of pixels contain common drain electrodes. The source electrode of each pixel TFT is connected to its pixel electrode, and is electrically isolated from every other circuit element in the pixel array.

Nanostructured gold microelectrodes for extracellular recording from electrogenic cells.

PubMed

Brüggemann, D; Wolfrum, B; Maybeck, V; Mourzina, Y; Jansen, M; Offenhäusser, A

2011-07-01

We present a new biocompatible nanostructured microelectrode array for extracellular signal recording from electrogenic cells. Microfabrication techniques were combined with a template-assisted approach using nanoporous aluminum oxide to develop gold nanopillar electrodes. The nanopillars were approximately 300-400 nm high and had a diameter of 60 nm. Thus, they yielded a higher surface area of the electrodes resulting in a decreased impedance compared to planar electrodes. The interaction between the large-scale gold nanopillar arrays and cardiac muscle cells (HL-1) was investigated via focused ion beam milling. In the resulting cross-sections we observed a tight coupling between the HL-1 cells and the gold nanostructures. However, the cell membranes did not bend into the cleft between adjacent nanopillars due to the high pillar density. We performed extracellular potential recordings from HL-1 cells with the nanostructured microelectrode arrays. The maximal amplitudes recorded with the nanopillar electrodes were up to 100% higher than those recorded with planar gold electrodes. Increasing the aspect ratio of the gold nanopillars and changing the geometrical layout can further enhance the signal quality in the future.

Electrical stimulus artifact cancellation and neural spike detection on large multi-electrode arrays.

PubMed

Mena, Gonzalo E; Grosberg, Lauren E; Madugula, Sasidhar; Hottowy, Paweł; Litke, Alan; Cunningham, John; Chichilnisky, E J; Paninski, Liam

2017-11-01

Simultaneous electrical stimulation and recording using multi-electrode arrays can provide a valuable technique for studying circuit connectivity and engineering neural interfaces. However, interpreting these measurements is challenging because the spike sorting process (identifying and segregating action potentials arising from different neurons) is greatly complicated by electrical stimulation artifacts across the array, which can exhibit complex and nonlinear waveforms, and overlap temporarily with evoked spikes. Here we develop a scalable algorithm based on a structured Gaussian Process model to estimate the artifact and identify evoked spikes. The effectiveness of our methods is demonstrated in both real and simulated 512-electrode recordings in the peripheral primate retina with single-electrode and several types of multi-electrode stimulation. We establish small error rates in the identification of evoked spikes, with a computational complexity that is compatible with real-time data analysis. This technology may be helpful in the design of future high-resolution sensory prostheses based on tailored stimulation (e.g., retinal prostheses), and for closed-loop neural stimulation at a much larger scale than currently possible.

Life on magnets: stem cell networking on micro-magnet arrays.

PubMed

Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M; Syková, Eva

2013-01-01

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field's value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine.

Life on Magnets: Stem Cell Networking on Micro-Magnet Arrays

PubMed Central

Zablotskii, Vitalii; Dejneka, Alexandr; Kubinová, Šárka; Le-Roy, Damien; Dumas-Bouchiat, Frédéric; Givord, Dominique; Dempsey, Nora M.; Syková, Eva

2013-01-01

Interactions between a micro-magnet array and living cells may guide the establishment of cell networks due to the cellular response to a magnetic field. To manipulate mesenchymal stem cells free of magnetic nanoparticles by a high magnetic field gradient, we used high quality micro-patterned NdFeB films around which the stray field’s value and direction drastically change across the cell body. Such micro-magnet arrays coated with parylene produce high magnetic field gradients that affect the cells in two main ways: i) causing cell migration and adherence to a covered magnetic surface and ii) elongating the cells in the directions parallel to the edges of the micro-magnet. To explain these effects, three putative mechanisms that incorporate both physical and biological factors influencing the cells are suggested. It is shown that the static high magnetic field gradient generated by the micro-magnet arrays are capable of assisting cell migration to those areas with the strongest magnetic field gradient, thereby allowing the build up of tunable interconnected stem cell networks, which is an elegant route for tissue engineering and regenerative medicine. PMID:23936425

Optimization of focality and direction in dense electrode array transcranial direct current stimulation (tDCS)

NASA Astrophysics Data System (ADS)

Guler, Seyhmus; Dannhauer, Moritz; Erem, Burak; Macleod, Rob; Tucker, Don; Turovets, Sergei; Luu, Phan; Erdogmus, Deniz; Brooks, Dana H.

2016-06-01

Objective. Transcranial direct current stimulation (tDCS) aims to alter brain function non-invasively via electrodes placed on the scalp. Conventional tDCS uses two relatively large patch electrodes to deliver electrical current to the brain region of interest (ROI). Recent studies have shown that using dense arrays containing up to 512 smaller electrodes may increase the precision of targeting ROIs. However, this creates a need for methods to determine effective and safe stimulus patterns as the number of degrees of freedom is much higher with such arrays. Several approaches to this problem have appeared in the literature. In this paper, we describe a new method for calculating optimal electrode stimulus patterns for targeted and directional modulation in dense array tDCS which differs in some important aspects with methods reported to date. Approach. We optimize stimulus pattern of dense arrays with fixed electrode placement to maximize the current density in a particular direction in the ROI. We impose a flexible set of safety constraints on the current power in the brain, individual electrode currents, and total injected current, to protect subject safety. The proposed optimization problem is convex and thus efficiently solved using existing optimization software to find unique and globally optimal electrode stimulus patterns. Main results. Solutions for four anatomical ROIs based on a realistic head model are shown as exemplary results. To illustrate the differences between our approach and previously introduced methods, we compare our method with two of the other leading methods in the literature. We also report on extensive simulations that show the effect of the values chosen for each proposed safety constraint bound on the optimized stimulus patterns. Significance. The proposed optimization approach employs volume based ROIs, easily adapts to different sets of safety constraints, and takes negligible time to compute. An in-depth comparison study gives insight into the relationship between different objective criteria and optimized stimulus patterns. In addition, the analysis of the interaction between optimized stimulus patterns and safety constraint bounds suggests that more precise current localization in the ROI, with improved safety criterion, may be achieved by careful selection of the constraint bounds.

Interferometric characterization of pyroelectrically activated micro-arrays of liquid lenses in lithium niobate crystals

NASA Astrophysics Data System (ADS)

Grilli, S.; Miccio, L.; Vespini, V.; Ferraro, P.

2008-08-01

In recent years a wide variety of liquid based optical elements have been conceived, designed and fabricated even for commercial products like digital cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new field of investigation named optofludics. Among other things, the optofluidic area deals with the investigation and the realization of liquid micro-lenses. Different methods and configurations have been proposed in literature to achieve liquid variable micro-lenses. This paper reports about the possibility to achieve lensing effect by a relatively easy to accomplish technique based on an open microfluidic system consisting of a tiny amount of appropriate liquid manipulated by the pyroelectric effect onto a periodically poled LiNbO3 substrate. Basically, an electrowetting process is performed to actuate the liquid film by using the surface charges generated pyroelectrically under temperature variation. The configuration is electrode-less compared to standard electrowetting systems, thus improving the device flexibility and easiness of fabrication. The curvature of the liquid lenses has been characterized by interferometric techniques based on the evaluation of the phase map through digital holography. The results showing the evolution of the lens curvature with the temperature variation will be presented and discussed.