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Sample records for addressable electrode arrays

  1. Method for the electro-addressable functionalization of electrode arrays

    SciTech Connect

    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.

  2. Individually addressable electrode array for multianalyte electrochemiluminescent immunoassay based on a sequential triggering strategy.

    PubMed

    Wang, Lin; Wei, Wei; Han, Jing; Fu, Zhifeng

    2012-02-01

    Multianalyte immunoassay in a single run is often necessary to monitor or quantitate several components in a complex sample matrix for various purposes. In this paper we present a novel, individually addressable electrode array for sequential electrochemiluminescent (ECL) immunoassay using a non-array detector. An immunosensor array was fabricated by site-selectively immobilizing multiple antigens on different electrodes. With a competitive immunoassay format, the amounts of the bound Ru(bpy)(3)(2+) derivative labeled antibodies decreased with the increase of the antigens in the sample, and the ECL signals from different immunosensors were collected in turn by a photomultiplier with the aid of a home-made single-pore-three-throw switch. Using human IgG and rat IgG as model analytes, this multianalyte immunoassay showed detection limits down to 8.9 and 7.2 ng mL(-1) for them, respectively. The results for real sample analysis demonstrated that this strategy can provide a simple, sensitive, low-cost and high-throughput ECL immunosensor array for clinical diagnosis. PMID:22159267

  3. Collection, focusing, and metering of DNA in microchannels using addressable electrode arrays for portable low-power bioanalysis

    PubMed Central

    Shaikh, Faisal A.; Ugaz, Victor M.

    2006-01-01

    Although advances in microfluidic technology have enabled increasingly sophisticated biosensing and bioassay operations to be performed at the microscale, many of these applications employ such small amounts of charged biomolecules (DNA, proteins, and peptides) that they must first be preconcentrated to a detectable level. Efficient strategies for precisely handling minute quantities of biomolecules in microchannel geometries are critically needed; however, it has proven challenging to achieve simultaneous concentration, focusing, and metering capabilities with current-generation sample-injection technology. By using microfluidic chips incorporating arrays of individually addressable microfabricated electrodes, we demonstrate that DNA can be sequentially concentrated, focused into a narrow zone, metered, and injected into an analysis channel. This technique transports charged biomolecules between active electrodes upon application of a small potential difference (1 V) and is capable of achieving orders of magnitude concentration increases within a small device footprint. The collected samples are highly focused, with sample zone size and shape defined solely by electrode geometry. PMID:16551750

  4. Signal Amplification in a Microchannel from Redox Cycling with Varied Electroactive Configurations of an Individually-Addressable Microband Electrode Array

    PubMed Central

    Lewis, Penny M.; Sheridan, Leah Bullard; Gawley, Robert E.; Fritsch, Ingrid

    2010-01-01

    Amperometric detection at microelectrodes in lab-on-a-chip (LOAC) devices lose advantages in signal-to-background ratio, reduced ohmic iR drop, and steady-state signal when volumes are so small that diffusion fields reach the walls before flux becomes fully radial. Redox-cycling of electroactive species between multiple, closely-spaced microelectrodes offsets that limitation and provides amplification capabilities. A device that integrates a microchannel with an individually-addressable microband electrode array has been used to study effects of signal amplification due to redox cycling in a confined, static solution with different configurations and numbers of active generators and collectors. The microfabricated device consists of a 22-μm high, 600-μm wide microchannel containing an array of 50-μm wide, 600-μm long gold microbands, separated by 25-μm gaps, interspersed with an 800-μm-wide counter electrode and 400-μm wide passive conductor, with a distant but on-chip 400-μm wide pseudoreference electrode. Investigations involve solutions of potassium chloride electrolyte containing potassium ferrocyanide. Amplification factors were as high as 7.60, even with these microelectrodes of fairly large dimensions (which are generally less expensive, easier, and more reproducible to fabricate), because of the significant role that passive and active (instrumentally induced) redox-cycling plays in confined volumes of enclosed microchannels. The studies are useful in optimizing designs for LOAC-devices. PMID:20108925

  5. Electrode array for neural stimulation

    DOEpatents

    Wessendorf, Kurt O.; Okandan, Murat; Stein, David J.; Yang, Pin; Cesarano, III, Joseph; Dellinger, Jennifer

    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.

  6. 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.

  7. Flexible retinal electrode array

    DOEpatents

    Okandan, Murat; Wessendorf, Kurt O.; Christenson, Todd R.

    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.

  8. Matrix-addressable, active electrode arrays for neural stimulation using organic semiconductors—cytotoxicity and pilot experiments in vivo

    NASA Astrophysics Data System (ADS)

    Feili, Dara; Schuettler, Martin; Stieglitz, Thomas

    2008-03-01

    Organic field effect transistors can be integrated into micromachined polyimide-based neural stimulation electrode arrays in order to build active switching matrices. With this approach, a matrix of N × M electrode contacts requires only N + M interconnects to a stimulator when active switching elements are used instead of N × M interconnects. In this paper, we demonstrated that pentacene-based organic field effect transistors (OFETs) can be used to drive stimulation currents through neural electrodes in a physiological-like environment. In order to prove the general applicability as an implant material, the cytotoxicity of pentacene was evaluated with respect to potential effects on cell viability. The results of these tests indicate that extracts from pentacene inhibit neither proliferation nor metabolism of the tested mouse fibroblasts. However, some effect on cell spreading was observed when cells were in direct contact to pentacene for 48 h. In pilot experiments it was demonstrated for the very first time that pentacene transistors can be used as switching elements, acting as voltage-controlled current sources, capable of driving currents suitable for electrical stimulation of a peripheral nerve via a tripolar cuff electrode.

  9. 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.

  10. Coated carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng; Wen, Jian; Chen, Jinghua; Huang, Zhongping; Wang, Dezhi

    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.

  11. 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.

  12. Stretchable Micro-Electrode Array

    SciTech Connect

    Maghribi, M; Hamilton, J; Polla, D; Rose, K; Wilson, T; Krulevitch, P

    2002-03-08

    This paper focuses on the design consideration, fabrication processes and preliminary testing of the stretchable micro-electrode array. We are developing an implantable, stretchable micro-electrode array using polymer-based microfabrication techniques. The device will serve as the interface between an electronic imaging system and the human eye, directly stimulating retinal neurons via thin film conducting traces and electroplated electrodes. The metal features are embedded within a thin ({approx}50 micron) substrate fabricated using poly (dimethylsiloxane) (PDMS), a biocompatible elastomeric material that has very low water permeability. The conformable nature of PDMS is critical for ensuring uniform contact with the curved surface of the retina. To fabricate the device, we developed unique processes for metalizing PDMS to produce robust traces capable of maintaining conductivity when stretched (5%, SD 1.5), and for selectively passivating the conductive elements. An in situ measurement of residual strain in the PDMS during curing reveals a tensile strain of 10%, explaining the stretchable nature of the thin metalized devices.

  13. 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.

  14. Photosensitive biosensor array system using optical addressing without an addressing circuit on array biochips

    NASA Astrophysics Data System (ADS)

    Ahn, Chang-Geun; Ah, Chil Seong; Kim, Tae-Youb; Park, Chan Woo; Yang, Jong-Heon; Kim, Ansoon; Sung, Gun Yong

    2010-09-01

    This paper introduces a photosensitive biosensor array system with a simple photodiode array that detects photocurrent changes caused by reactions between probe and target molecules. Using optical addressing, the addressing circuit on the array chip is removed for low-cost application, and real cell addressing is achieved using an externally located computer-controllable light-emitting diode array module. The fabricated biosensor array chip shows a good dynamic range of 1-100 ng/mL under prostate-specific antigen detection, with an on-chip resolution of roughly 1 ng/mL.

  15. 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.

  16. Algal biosensor array on a single electrode.

    PubMed

    Tatsuma, Tetsu; Yoshida, Yutaka; Shitanda, Isao; Notsu, Hideo

    2009-02-01

    An algal array was prepared on a single transparent electrode, and photosynthetic activity of each algal channel and its inhibition by a toxin were monitored with a single-channel potentiostat by successive light irradiation with a LED array. PMID:19173040

  17. Microminiature molding techniques for cochlear electrode arrays.

    PubMed

    Loeb, G E; Peck, R A; Smith, D W

    1995-12-01

    We provide a general method for producing a variety of small, complex electrode arrays based on injection molds produced using computer-aided drafting and machining (CAD-CAM) procedures and a novel method for connecting to the very fine electrical leads associated with the individual contacts of such arrays. Cat-sized cochlear electrode arrays with up to eight contacts were built according to these methods and their electrical contacts were characterized in vitro by impedance spectroscopy and in vivo by monitoring impedance for over 1 year of intermittent stimulation in chronically instrumented animals. PMID:8788052

  18. Electrochemical Patterning and Detection of DNA Arrays on a Two-Electrode Platform

    PubMed Central

    Furst, Ariel; Landefeld, Sally; Hill, Michael G.; Barton, Jacqueline K.

    2014-01-01

    We report a novel method of DNA array formation that is electrochemically formed and addressed with a two-electrode platform. Electrochemical activation of a copper catalyst, patterned with one electrode, enables precise placement of multiple sequences of DNA onto a second electrode surface. The two-electrode patterning and detection platform allows for both spatial resolution of the patterned DNA array and optimization of detection through DNA-mediated charge transport with electrocatalysis. This two-electrode platform has been used to form arrays that enable differentiation between well-matched and mismatched sequences, the detection of TATA-binding protein, and sequence-selective DNA hybridization. PMID:24328227

  19. Electrochemical patterning and detection of DNA arrays on a two-electrode platform.

    PubMed

    Furst, Ariel; Landefeld, Sally; Hill, Michael G; Barton, Jacqueline K

    2013-12-26

    We report a novel method of DNA array formation that is electrochemically formed and addressed with a two-electrode platform. Electrochemical activation of a copper catalyst, patterned with one electrode, enables precise placement of multiple sequences of DNA onto a second electrode surface. The two-electrode patterning and detection platform allows for both spatial resolution of the patterned DNA array and optimization of detection through DNA-mediated charge transport with electrocatalysis. This two-electrode platform has been used to form arrays that enable differentiation between well-matched and mismatched sequences, the detection of TATA-binding protein, and sequence-selective DNA hybridization. PMID:24328227

  20. Optically transparent multi-suction electrode arrays

    PubMed Central

    Nagarah, John M.; Stowasser, Annette; Parker, Rell L.; Asari, Hiroki; Wagenaar, Daniel A.

    2015-01-01

    Multielectrode arrays (MEAs) allow for acquisition of multisite electrophysiological activity with submillisecond temporal resolution from neural preparations. The signal to noise ratio from such arrays has recently been improved by substrate perforations that allow negative pressure to be applied to the tissue; however, such arrays are not optically transparent, limiting their potential to be combined with optical-based technologies. We present here multi-suction electrode arrays (MSEAs) in quartz that yield a substantial increase in the detected number of units and in signal to noise ratio from mouse cortico-hippocampal slices and mouse retina explants. This enables the visualization of stronger cross correlations between the firing rates of the various sources. Additionally, the MSEA's transparency allows us to record voltage sensitive dye activity from a leech ganglion with single neuron resolution using widefield microscopy simultaneously with the electrode array recordings. The combination of enhanced electrical signals and compatibility with optical-based technologies should make the MSEA a valuable tool for investigating neuronal circuits. PMID:26539078

  1. Transparent metal electrodes from ordered nanosphere arrays

    NASA Astrophysics Data System (ADS)

    Morfa, Anthony J.; Akinoglu, Eser M.; Subbiah, Jegadesan; Giersig, Michael; Mulvaney, Paul

    2013-08-01

    We show that perforated metal electrode arrays, fabricated using nanosphere lithography, provide a viable alternative to conductive metal oxides as transparent electrode materials. The inter-aperture spacing is tuned by varying etching times in an oxygen plasma, and the effect of inter-aperture "wire" thickness on the optical and electronic properties of perforated silver films is shown. Optical transmission is limited by reflection and surface plasmons, and for these results do not exceed 73%. Electrical sheet resistance is shown to be as low as 3 Ω ◻-1 for thermally evaporated silver films. The performance of organic photovoltaic devices comprised of a P3HT:PCBM bulk heterojunction deposited onto perforated metal arrays is shown to be limited by optical transmission, and a simple model is presented to overcome these limitations.

  2. Integrated Arrays of Ion-Sensitive Electrodes

    NASA Technical Reports Server (NTRS)

    Buehler, Martin; Kuhlman, Kimberly

    2003-01-01

    The figure depicts an example of proposed compact water-quality sensors that would contain integrated arrays of ion-sensitive electrodes (ISEs). These sensors would serve as electronic "tongues": they would be placed in contact with water and used to "taste" selected dissolved ions (that is, they would be used to measure the concentrations of the ions). The selected ions could be any or all of a variety of organic and inorganic cations and anions that could be regarded as contaminants or analytes, depending on the specific application. In addition, some of the ISEs could be made sensitive to some neutral analytes

  3. Silicon-based wire electrode array for neural interfaces

    NASA Astrophysics Data System (ADS)

    Pei, Weihua; Zhao, Hui; Zhao, Shanshan; Fang, Xiaolei; Chen, Sanyuan; Gui, Qiang; Tang, Rongyu; Chen, Yuanfang; Hong, Bo; Gao, Xiaorong; Chen, Hongda

    2014-09-01

    Objectives. Metal-wire electrode arrays are widely used to record and stimulate neurons. Commonly, these devices are fabricated from a long insulated metal wire by cutting it into the proper length and using the cross-section as the electrode site. The assembly of a micro-wire electrode array with regular spacing is difficult. With the help of micro-machine technology, a silicon-based wire electrode array (SWEA) is proposed to simplify the assembling process and provide a wire-type electrode with tapered tips. Approach. Silicon wires with regular spacing coated with metal are generated from a silicon wafer through micro-fabrication and are ordered into a 3D array. A silicon wafer is cut into a comb-like structure with hexagonal teeth on both sides by anisotropic etching. To establish an array of silicon-based linear needles through isotropic wet etching, the diameters of these hexagonal teeth are reduced; their sharp edges are smoothed out and their tips are sharpened. The needle array is coated with a layer of parylene after metallization. The tips of the needles are then exposed to form an array of linear neural electrodes. With these linear electrode arrays, an array of area electrodes can be fabricated. Main results. A 6  ×  6 array of wire-type electrodes based on silicon is developed using this method. The time required to manually assemble the 3D array decreases significantly with the introduction of micro-fabricated 2D array. Meanwhile, the tip intervals in the 2D array are accurate and are controlled at no more than 1%. The SWEA is effective both in vitro and in vivo. Significance. Using this method, the SWEA can be batch-prepared in advance along with its parameters, such as spacing, length, and diameter. Thus, neural scientists can assemble proper electrode arrays in a short time.

  4. Rolling silver nanowire electrodes: simultaneously addressing adhesion, roughness, and conductivity.

    PubMed

    Hauger, Tate C; Al-Rafia, S M Ibrahim; Buriak, Jillian M

    2013-12-11

    Silver nanowire mesh electrodes represent a possible mass-manufacturable route toward transparent and flexible electrodes for plastic-based electronics such as organic photovoltaics (OPVs), organic light emitting diodes (OLEDs), and others. Here we describe a route that is based upon spray-coated silver nanowire meshes on polyethylene terephthalate (PET) sheets that are treated with a straightforward combination of heat and pressure to generate electrodes that have low sheet resistance, good optical transmission, that are topologically flat, and adhere well to the PET substrate. The silver nanowire meshes were prepared by spray-coating a solution of silver nanowires onto PET, in air at slightly elevated temperatures. The as-prepared silver nanowire electrodes are highly resistive due to the poor contact between the individual silver nanowires. Light pressure applied with a stainless steel rod, rolled over the as-sprayed silver nanowire meshes on PET with a speed of 10 cm s(-1) and a pressure of 50 psi, results in silver nanowire mesh arrays with sheet resistances of less than 20 Ω/□. Bending of these rolled nanowire meshes on PET with different radii of curvature, from 50 to 0.625 mm, showed no degradation of the conductivity of the electrodes, as shown by the constant sheet resistance before and after bending. Repeated bending (100 times) around a rod with a radius of curvature of 1 mm also showed no increase in the sheet resistance, demonstrating good adherence and no signs of delamination of the nanowire mesh array. The diffuse and direct transmittance of the silver nanowires (both rolled and as-sprayed) was measured for wavelengths from 350 to 1200 nm, and the diffuse transmission was similar to that of the PET substrate; the direct transmission decreases by about 7-8%. The silver nanowires were then incorporated into OPV devices with the following architecture: transparent electrode/PEDOT:PSS/P3HT:PC61BM/LiF/Al. While slightly lower in efficiency than the

  5. 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

  6. Modiolus-hugging intracochlear electrode array with shape memory alloy.

    PubMed

    Min, Kyou Sik; Jun, Sang Beom; 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

  7. A flexible microchannel electrode array for peripheral nerves to interface with neural prosthetics

    NASA Astrophysics Data System (ADS)

    Landrith, Ryan; Nothnagle, Caleb; Kim, Young-tae; Wijesundara, Muthu B. J.

    2016-05-01

    In order to control neural prosthetics by recording signals from peripheral nerves with the required specificity, high density electrode arrays that can be easily implanted on very small peripheral nerves (50μm-500μm) are needed. Interfacing with these small nerves is surgically challenging due to their size and fragile nature. To address this problem, a Flexible MicroChannel Electrode Array for interfacing with small diameter peripheral nerves and nerve fascicles was developed. The electrochemical characterization and electrophysiological recordings from the common peroneal nerve of a rat are presented along with demonstration of the surgical ease-of-use of the array.

  8. Compensated individually addressable array technology for human breast imaging

    DOEpatents

    Lewis, D. Kent

    2003-01-01

    A method of forming broad bandwidth acoustic or microwave beams which encompass array design, array excitation, source signal preprocessing, and received signal postprocessing. This technique uses several different methods to achieve improvement over conventional array systems. These methods are: 1) individually addressable array elements; 2) digital-to-analog converters for the source signals; 3) inverse filtering from source precompensation; and 4) spectral extrapolation to expand the bandwidth of the received signals. The components of the system will be used as follows: 1) The individually addressable array allows scanning around and over an object, such as a human breast, without any moving parts. The elements of the array are broad bandwidth elements and efficient radiators, as well as detectors. 2) Digital-to-analog converters as the source signal generators allow virtually any radiated field to be created in the half-space in front of the array. 3) Preprocessing allows for corrections in the system, most notably in the response of the individual elements and in the ability to increase contrast and resolution of signal propagating through the medium under investigation. 4) Postprocessing allows the received broad bandwidth signals to be expanded in a process similar to analytic continuation. Used together, the system allows for compensation to create beams of any desired shape, control the wave fields generated to correct for medium differences, and improve contract and resolution in and through the medium.

  9. 3D electrical tomographic imaging using vertical arrays of electrodes

    NASA Astrophysics Data System (ADS)

    Murphy, S. C.; Stanley, S. J.; Rhodes, D.; York, T. A.

    2006-11-01

    Linear arrays of electrodes in conjunction with electrical impedance tomography have been used to spatially interrogate industrial processes that have only limited access for sensor placement. This paper explores the compromises that are to be expected when using a small number of vertically positioned linear arrays to facilitate 3D imaging using electrical tomography. A configuration with three arrays is found to give reasonable results when compared with a 'conventional' arrangement of circumferential electrodes. A single array yields highly localized sensitivity that struggles to image the whole space. Strategies have been tested on a small-scale version of a sludge settling application that is of relevance to the industrial sponsor. A new electrode excitation strategy, referred to here as 'planar cross drive', is found to give superior results to an extended version of the adjacent electrodes technique due to the improved uniformity of the sensitivity across the domain. Recommendations are suggested for parameters to inform the scale-up to industrial vessels.

  10. Content addressable systolic array for sparse matrix computation

    SciTech Connect

    Wing, O.

    1983-01-01

    A systolic array is proposed which is specifically designed to solve a system of sparse linear equations. The array consists of a number of processing elements connected in a ring. Each processing element has its own content addressable memory where the nonzero elements of the sparse matrix are stored. Matrix elements to which elementary operations are applied are extracted from the memory by content addressing. The system of equations is solved in a systolic fashion and the solution is obtained in nz+5n-2 steps where nz is the number of nonzero elements along and below the diagonal and n is the number of equations. 13 references.

  11. Optimal configuration of an electrode array for measuring ventricles' contraction

    NASA Astrophysics Data System (ADS)

    Lewandowska, M.; Poliński, A.; Truyen, B.; Wtorek, J.

    2013-04-01

    An influence of an electrode-array configuration on an impedance signal composition for a fixed spatial distribution of its sources is examined in the paper. The Finite Element Method and Geselowitz relationship were used for examining three different electrode-arrays. A sensitivity approach was used to evaluate each configuration assuming that localization of the signal source is known. A conductivity change, thus the source of the impedance signal was considered as two hemispheres covered by a shell.

  12. An addressable cell array for a platform of biosensor chips

    NASA Astrophysics Data System (ADS)

    Yang, Seungkyoung; Choi, Soo-hee; Jung, Moon Youn; Song, Kibong; Park, Jeong Won

    2013-05-01

    In order to detect interested matters in fields, various lab-on-a-chips where chemical, physical, or biological sensors are loaded have been developed. eNOSE can be a representative example among them. Because animals can sense 300~1000 different chemicals by olfactory system - smell -, the olfactory system has been spotlighted as new materials in the field of sensing. Those investigations, however, are usually focused on how to detect signals from the olfactory neurons or receptors loaded on chips and enhance sensing efficacy of chips. Therefore, almost of those chips are designed for only one material sensing. Multi-sensing using multi-channels will be needed when the olfactory systems are adopted well on chips. For multiple sensing, we developed an addressable cell array. The chip has 38 cell-chambers arranged in a circle shape and different cell types of thirty eight can be allocated with specific addresses on the chip without any complex valve system. In order to confirm the cell addressing, we loaded EGFP-transfected and empty vector-transfected HEK293a cells into inlets of the cell array in a planned address and those cells were positioned into each chamber by brief aspiration. The arrayed cells were confirmed as a specific pattern through EGFP and nuclei staining. This cell array which can generate address of sensor materials like cells with their own specification is expected to be applied to a platform for a biosensor chip at various sensing fields.

  13. 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. PMID:25863691

  14. 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

  15. Developing barbed microtip-based electrode arrays for biopotential measurement.

    PubMed

    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

  16. Ultramicroelectrode array behavior of one-dimensional organic conductor electrodes.

    PubMed

    Freund, M S; Brajter-Toth, A

    1989-05-01

    Tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) electrodes were prepared by two methods that produced electrodes with different structures. This was confirmed by scanning electron microscopy, which also revealed the ultramicroelectrode arraylike structure of TTF-TCNQ electrodes. Electrochemical behavior at both types of electrodes followed the predictions of the theory for ultramicroelectrode arrays. At the two types of surfaces that were prepared, apparent electrochemical rate constants of ferricyanide and ascorbate were different. The resulting changes in the apparent rate constants of redox couples such as ferricyanide and ascorbate as a function of surface structure suggest that at TTF-TCNQ control over reactivity can be achieved through structural manipulation. PMID:2729599

  17. System of fabricating a flexible electrode array

    DOEpatents

    Krulevitch, Peter; Polla, Dennis L.; Maghribi, Mariam N.; Hamilton, Julie; Humayun, Mark S.; Weiland, James D.

    2010-10-12

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  18. System of fabricating a flexible electrode array

    DOEpatents

    Krulevitch, Peter; Polla, Dennis L.; Maghribi, Mariam N.; Hamilton, Julie; Humayun, Mark S.; Weiland, James D.

    2012-01-28

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  19. Flexible electrode array for artifical vision

    DOEpatents

    Krulevitch, Peter; Polla, Dennis L.; Maghribi, Mariam N.; Hamilton, Julie

    2006-12-05

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  20. Density controlled carbon nanotube array electrodes

    DOEpatents

    Ren, Zhifeng F.; Tu, Yi

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  1. Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants

    PubMed Central

    Kim, Eui Tae; Seo, Jong-Mo; Woo, Se Joon; Zhou, Jing Ai; Chung, Hum; Kim, Sung June

    2008-01-01

    Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between electrodes and targeting cell layers, which limits site resolution for effective multi-channel stimulation. In this paper, we report a newly designed device with a pillar structure that more effectively interfaces with the target. Electrode arrays were successfully fabricated and safely implanted inside the rabbit eye in suprachoroidal space. Optical Coherence Tomography (OCT) showed well-preserved pillar structures of the electrode without damage. Bipolar stimulation was applied through paired sites (6:1) and the neural responses were successfully recorded from several regions in the visual cortex. Electrically evoked cortical potential by the pillar electrode array stimulation were compared to visual evoked potential under full-field light stimulation.

  2. 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.

  3. A novel electron gun with an independently addressable cathode array

    SciTech Connect

    Rudys, Joseph Matthew; Reed, Kim Warren; Pena, Gary Edward; Schneider, Larry X.

    2006-08-01

    The design of a novel electron gun with an array of independently addressable cathode elements is presented. Issues relating to operation in a 6.5 Tesla axial magnetic field are discussed. Simulations with the TriComp electromagnetic field code that were used to determine the space charge limited tube characteristic and to model focusing of the electron beam in the magnetic field are reviewed. Foil heating and stress calculations are discussed. The results of CYLTRAN simulations yielding the energy spectrum of the electron beam and the current transmitted through the foil window are presented.

  4. 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

  5. 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. PMID:27246747

  6. Chronic impedance spectroscopy of an endovascular stent-electrode array

    NASA Astrophysics Data System (ADS)

    Opie, Nicholas L.; John, Sam E.; Rind, Gil S.; Ronayne, Stephen M.; Grayden, David B.; Burkitt, Anthony N.; May, Clive N.; O’Brien, Terence J.; Oxley, Thomas J.

    2016-08-01

    Objective. Recently, we reported a minimally invasive stent-electrode array capable of recording neural signals from within a blood vessel. We now investigate the use of electrochemical impedance spectroscopy (EIS) measurements to infer changes occurring to the electrode–tissue interface from devices implanted in a cohort of sheep for up to 190 days. Approach. In a cohort of 15 sheep, endovascular stent-electrode arrays were implanted in the superior sagittal sinus overlying the motor cortex for up to 190 days. EIS was performed routinely to quantify viable electrodes for up to 91 days. An equivalent circuit model (ECM) was developed from the in vivo measurements to characterize the electrode–tissue interface changes occurring to the electrodes chronically implanted within a blood vessel. Post-mortem histological assessment of stent and electrode incorporation into the wall of the cortical vessels was compared to the electrical impedance measurements. Main results. EIS could be used to infer electrode viability and was consistent with x-ray analysis performed in vivo, and post-mortem evaluation. Viable electrodes exhibited consistent 1 kHz impedances across the 91 day measurement period, with the peak resistance frequency for the acquired data also stable over time. There was a significant change in 100 Hz phase angles, increasing from ‑67.8° ± 8.8° at day 0 to ‑43.8° ± 0.8° at day 91, which was observed to stabilize after eight days. ECM’s modeled to the data suggested this change was due to an increase in the capacitance of the electrode–tissue interface. This was supported by histological assessment with >85% of the implanted stent struts covered with neointima and incorporated into the blood vessel within two weeks. Conclusion. This work demonstrated that EIS could be used to determine the viability of electrode implanted chronically within a blood vessel. Impedance measurements alone were not observed to be a useful predictor of alterations

  7. Preparation, applications, and digital simulation of carbon interdigitated array electrodes.

    PubMed

    Liu, Fei; Kolesov, Grigory; Parkinson, B A

    2014-08-01

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltammetry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10(-5) molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. PMID:24998907

  8. Preparation, Applications, and Digital Simulation of Carbon Interdigitated Array Electrodes

    SciTech Connect

    Liu, Fei; Kolesov, Grigory; Parkinson, Bruce A.

    2014-12-16

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltam-metry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10–5 molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science Office of Basic Energy Sciences.

  9. Cell pairing using microwell array electrodes based on dielectrophoresis.

    PubMed

    Yoshimura, Yuki; Tomita, Masahiro; Mizutani, Fumio; Yasukawa, Tomoyuki

    2014-07-15

    We report a simple device with an array of 10,000 (100 × 100) microwells for producing vertical pairs of cells in individual microwells with a rapid manipulation based on positive dielectrophoresis (p-DEP). The areas encircled with micropoles which fabricated from an electrical insulating photosensitive polymer were used as microwells. The width (14 μm) and depth (25 μm) of the individual microwells restricted the size to two vertically aligned cells. The DEP device for the manipulation of cells consisted of a microfluidic channel with an upper indium tin oxide (ITO) electrode and a lower microwell array electrode fabricated on an ITO substrate. Mouse myeloma cells stained in green were trapped within 1 s in the microwells by p-DEP by applying an alternating current voltage between the upper ITO and the lower microwell array electrode. The cells were retained inside the wells even after switching off the voltage and washing with a fluidic flow. Other myeloma cells stained in blue were then trapped in the microwells occupied by the cells stained in green to form the vertical cell pairing in the microwells. Cells stained in different colors were paired within only 1 min and a pairing efficiency of over 50% was achieved. PMID:24947270

  10. The fabrication of low-impedance nanoporous gold multiple-electrode arrays for neural electrophysiology studies

    PubMed Central

    Seker, Erkin; Berdichevsky, Yevgeny; Begley, Matthew R; Reed, Michael L; Staley, Kevin J; Yarmush, Martin L

    2011-01-01

    Neural electrodes are essential tools for the study of the nervous system and related diseases. Low electrode impedance is a figure of merit for sensitive detection of neural electrical activity and numerous studies have aimed to reduce impedance. Unfortunately, most of these efforts have been tethered by a combination of poor functional coating adhesion, complicated fabrication techniques, and poor fabrication repeatability. We address these issues with a facile method for reliably producing multiple-electrode arrays with low impedance by patterning highly adherent nanoporous gold films using conventional microfabrication techniques. The high surface area-to-volume ratio of self-assembled nanoporous gold results in a more than 25-fold improvement in the electrode-electrolyte impedance, where at 1 kHz, 850 kΩ impedance for conventional Au electrodes is reduced to 30 kΩ for nanoporous gold electrodes. Low impedance provides a superior signal-to-noise ratio for detection of neural activity in noisy environments. We systematically studied the effect of film morphology on electrode impedance and successfully recorded field potentials from rat hippocampal slices. Here, we present our fabrication approach, the relationship between film morphology and impedance, and field potential recordings. PMID:20203356

  11. Effect of embedded optical fibres on the mechanical properties of cochlear electrode arrays.

    PubMed

    Carland, Emma M; Stoddart, Paul R; Cadusch, Peter J; Fallon, James B; Wade, Scott A

    2016-02-01

    Incorporating optical fibres in cochlear electrode arrays has been proposed to provide sensors to help minimise insertion trauma and also for the delivery of light in optical nerve stimulation applications. However, embedding an optical fibre into an electrode array may change its stiffness properties, which can affect the level of trauma during insertion. This report uses measurements of buckling and deflection force to compare the stiffness properties of a range of cochlear electrode arrays (Nucleus straight array, rat array, cat array and guinea pig array) with custom arrays containing an embedded optical fibre. The cladding diameters of the optical fibres tested were 125 µm, 80 µm and 50 µm. The results show that the stiffness of the optical-fibre-embedded arrays is related to the diameter of the optical fibre. Comparison with wired arrays suggests optical fibres with a diameter of 50 µm could be embedded into an electrode array without significantly changing the stiffness properties of the array. PMID:26776375

  12. Conical Gradient Junctions of Dendritic Viologen Arrays on Electrodes

    NASA Astrophysics Data System (ADS)

    Kawauchi, Takehiro; Oguchi, Yuki; Nagai, Keiji; Iyoda, Tomokazu

    2015-06-01

    The three-dimensional construction of arrays of functional molecules on an electrode surface, such as organic semiconductors and redox-active molecules, is a considerable challenge in the fabrication of sophisticated junctions for molecular devices. In particular, well-defined organic layers with precise molecular gradients are anticipated to function as novel metal/organic interfaces with specific electrical properties, such as a space charge layer at the metal/semiconductor interface. Here, we report a strategy for the construction of a three-dimensional molecular array with an electrical connection to a metal electrode by exploiting dendritic molecular architecture. Newly designed dendritic molecules consisting of viologens (1,1‧-disubstituted-4,4‧-bipyridilium salts) as the framework and mercapto groups as anchor units form unique self-assembled monolayers (SAMs) on a gold surface reflecting the molecular design. The dendritic molecules exhibit a conical shape and closely pack to form cone arrays on the substrate, whereas, in solution, they expand into more flexible conformations. Differences in the introduction position of the anchor units in the dendritic structure result in apical- and basal-type cone arrays in which the spatial concentration of the viologen units can be precisely configured in the cones. The concentration in apical-type SAMs increases away from the substrate, whereas the opposite is true in basal-type SAMs.

  13. Conical Gradient Junctions of Dendritic Viologen Arrays on Electrodes

    PubMed Central

    Kawauchi, Takehiro; Oguchi, Yuki; Nagai, Keiji; Iyoda, Tomokazu

    2015-01-01

    The three-dimensional construction of arrays of functional molecules on an electrode surface, such as organic semiconductors and redox-active molecules, is a considerable challenge in the fabrication of sophisticated junctions for molecular devices. In particular, well-defined organic layers with precise molecular gradients are anticipated to function as novel metal/organic interfaces with specific electrical properties, such as a space charge layer at the metal/semiconductor interface. Here, we report a strategy for the construction of a three-dimensional molecular array with an electrical connection to a metal electrode by exploiting dendritic molecular architecture. Newly designed dendritic molecules consisting of viologens (1,1′-disubstituted-4,4′-bipyridilium salts) as the framework and mercapto groups as anchor units form unique self-assembled monolayers (SAMs) on a gold surface reflecting the molecular design. The dendritic molecules exhibit a conical shape and closely pack to form cone arrays on the substrate, whereas, in solution, they expand into more flexible conformations. Differences in the introduction position of the anchor units in the dendritic structure result in apical- and basal-type cone arrays in which the spatial concentration of the viologen units can be precisely configured in the cones. The concentration in apical-type SAMs increases away from the substrate, whereas the opposite is true in basal-type SAMs. PMID:26057120

  14. A carbon-fiber electrode array for long-term neural recording

    PubMed Central

    Guitchounts, Grigori; Markowitz, Jeffrey E.; Liberti, William A.; Gardner, Timothy J.

    2013-01-01

    Problem addressed Chronic neural recording in behaving animals is an essential method for studies of neural circuit function. However, stable recordings from small, densely packed neurons remains challenging, particularly over time-scales relevant for learning. Methodology We describe an assembly method for a 16 channel electrode array consisting of carbon fibers (<5 μm diameter) individually insulated with Parylene-C and fire-sharpened. The diameter of the array is approximately 26 microns, along the full extent of the implant. Results Carbon fiber arrays were tested in HVC (used as a proper name), a song motor nucleus, of singing zebra finches where individual neurons discharge with temporally precise patterns. Previous reports of activity in this population of neurons has required the use of high impedance electrodes on movable microdrives. Here, the carbon fiber electrodes provided stable multi-unit recordings over time-scales of months. Spike-sorting indicated that the multi-unit signals were dominated by one, or a small number of cells. Stable firing patterns during singing confirmed the stability of these clusters over time-scales of months. In addition, from a total of 10 surgeries, 16 projection neurons were found. This cell type is characterized by sparse - stereotyped firing firing patterns, providing unambiguous confirmation of single cell recordings. Significance Carbon fiber electrode bundles may provide a scalable solution for long-term neural recordings of densely packed neurons. PMID:23860226

  15. Optimization of Thin-Film Configuration for Light-Addressable Stimulation Electrode

    NASA Astrophysics Data System (ADS)

    Suzurikawa, Jun; Kanzaki, Ryohei; Nakao, Masayuki; Jimbo, Yasuhiko; Takahashi, Hirokazu

    Light addressing is an emerging technique to optically address a virtual electrode on a photoconductive substrate. A thinner photoconductive layer of a light-addressable planar electrode can improve the spatial resolution of the light-addressed electrode. Voltage application to the electrode, however, causes strong electric field across the thin photoconductive layer with a significant avalanche effect, which induces undesired increase of dark current. Here, in order to overcome this problem, we investigated how photoconductive-layer thickness and passivation-layer conductivity impact on voltage-application-induced bright and dark charge densities. Consequently, suppression of dark charge density with thick photoconductive layer and low-conductive passivation layer is a key factor for optimization of light-addressable electrode. With this designing strategy, we developed a novel light-addressable electrode using titanium dioxide as photoconductor. To suppress avalanche effect, the thickness of the titanium-dioxide layer was designed to be 1.5 μm. The fabricated electrode turned out to have a sufficient photoelectric property; the bright charge density reached up to 70 μC/cm2 and the bright to dark charge density ratio, over 10, which can realize stimulation to cultured dissociated neurons.

  16. 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

  17. Vertically aligned carbon nanofiber nanoelectrode arrays: electrochemical etching and electrode reusability

    PubMed Central

    Gupta, Rakesh K.; Meyyappan, M.; Koehne, Jessica E.

    2014-01-01

    Vertically aligned carbon nanofibers in the form of nanoelectrode arrays were grown on nine individual electrodes, arranged in a 3 × 3 array geometry, in a 2.5 cm2 chip. Electrochemical etching of the carbon nanofibers was employed for electrode activation and enhancing the electrode kinetics. Here, we report the effects of electrochemical etching on the fiber height and electrochemical properties. Electrode regeneration by amide hydrolysis and electrochemical etching is also investigated for electrode reusability. PMID:25089188

  18. 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. PMID:27118384

  19. Operation of a planar-electrode ion-trap array with adjustable RF electrodes

    NASA Astrophysics Data System (ADS)

    Kumph, M.; Holz, P.; Langer, K.; Meraner, M.; Niedermayr, M.; Brownnutt, M.; Blatt, R.

    2016-02-01

    One path to realizing systems of trapped atomic ions suitable for large-scale quantum computing and simulation is to create a two-dimensional (2D) array of ion traps. Interactions between nearest-neighbouring ions could then be turned on and off by tuning the ions’ relative positions and frequencies. We demonstrate and characterize the operation of a planar-electrode ion-trap array. By driving the trap with a network of phase-locked radio-frequency resonators which provide independently variable voltage amplitudes we vary the position and motional frequency of a Ca+ ion in two-dimensions within the trap array. Work on fabricating a miniaturised form of this 2D trap array is also described, which could ultimately provide a viable architecture for large-scale quantum simulations.

  20. Microneedle Electrode Array for Electrical Impedance Myography to Characterize Neurogenic Myopathy.

    PubMed

    Li, Zhao; Li, Yi; Liu, Mingsheng; Cui, Liying; Yu, Yude

    2016-05-01

    Electrical impedance myography (EIM) is a noninvasive technique for neuromuscular assessment, wherein a low-intensity alternating current is applied to a muscle, and the consequent surface voltage patterns are evaluated. Commercial wet electrodes are most commonly used for EIM. However, these electrodes are not suitable for use on small muscles, as they do not effectively solve the problem of high electrode-skin contact impedance (ESCI) that negatively influences the quality of recorded biopotentials. To address this problem, we fabricated a novel microneedle electrode array (MEA) that consists of 124-µm-long microneedles. Compared to wet electrodes, the MEA could pierce through the outer skin surface in a painless and micro-invasive manner, and could thus effectively reduce ESCI. The MEA has excellent test-retest reproducibility, with intraclass correlation coefficients exceeding 0.920. When used in combination with EIM, the MEA differentiated the affected muscles from the unaffected muscles in patients with neurogenic myopathy, by using EIM parameters of reactance and phase (p = 0.023 and 0.008, respectively). Thus, the novel MEA is a practical and reusable device for EIM assessment in cases of neurogenic myopathy. However, further refinement of the electrode is needed to enhance the clinical application of the system. PMID:26407702

  1. Light-addressable amperometric electrodes for enzyme sensors based on direct quantum dot-electrode contacts

    NASA Astrophysics Data System (ADS)

    Riedel, M.; Göbel, G.; Parak, W. J.; Lisdat, F.

    2014-03-01

    Quantum dots allow the generation of charge carriers upon illumination. When these particles are attached to an electrode a photocurrent can be generated. This allows their use as a light-switchable layer on the surface. The QDs can not only exchange electronics with the electrode, but can also interact with donor or acceptor compounds in solution providing access to the construction of signal chains starting from an analytic molecule. The magnitude and the direction of the photocurrent depend on several factors such as electrode polarization, solution pH and composition. These defined dependencies have been evaluated with respect to the combination of QD-electrodes with enzyme reactions for sensorial purpose. CdSe/ZnS-QD-modified electrodes can be used to follow enzymatic reactions in solution based on the oxygen sensitivity. In order to develop a photoelectrochemical biosensor, e.g. glucose oxidase is immobilized on the CdSe/ZnS-electrode. One immobilization strategy applies the layer-by-layer-technique of GOD and a polyelectrolyte. Photocurrent measurements of such a sensor show a clear concentration dependent behavior. The principle of combing QD oxidase. The sensitivity of quantum dot electrodes can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be influenced by additional nanoparticles, but also by multiple layers of the QDs. In another direction of research it can be demonstrated that direct electron transfer from excited quantum dots can be achieved with the redox protein cytochrome c. This allows the detection of the protein, but also interaction partners such as a enzymes or superoxide.

  2. Electrical breakdown gas detector featuring carbon nanotube array electrodes.

    PubMed

    Kim, Seongyul; Pal, Sunil; Ajayan, Pulickel M; Borca-Tasciuc, Theodorian; Koratkar, Nikhil

    2008-01-01

    We demonstrate here detection of dichloro-difluoro-methane and oxygen in mixtures with helium using a carbon nanotube electrical breakdown sensor device. The sensor is comprised of an aligned array of multiwalled carbon nanotubes deposited on a nickel based super-alloy (Inconel 600) as the anode; the counter electrode is a planar nickel sheet. By monitoring the electrical breakdown characteristics of oxygen and dichloro-difluoro-methane in a background of helium, we find that the detection limit for dichloro-difluoro-methane is approximately 0.1% and the corresponding limit for oxygen is approximately 1%. A phenomenologigal model is proposed to describe the trends observed in detection of the two mixtures. These results indicate that carbon nanotube based electrical breakdown sensors show potential as end detectors in gas-chromatography devices. PMID:18468093

  3. Digital microfluidic operations on micro-electrode dot array architecture.

    PubMed

    Wang, G; Teng, D; Fan, S-K

    2011-12-01

    As digital microfluidics-based biochips find more applications, their complexity is expected to increase significantly owing to the trend of multiple and concurrent assays on the chip. There is a pressing need to deliver a top-down design methodology that the biochip designer can leverage the same level of computer-aided design support as the semi-conductor industry now does. Moreover, as microelectronics fabrication technology is scaling up and integrated device performance is improving, it is expected that these microfluidic biochips will be integrated with microelectronic components in next-generation system-on-chip designs. This study presents the analysis and experiments of digital microfluidic operations on a novel electrowetting-on-dielectric-based 'micro-electrode dot array architecture' that fosters a development path for hierarchical top-down design approach for digital microfluidics. The proposed architecture allows dynamic configurations and activations of identical basic microfluidic unit called 'micro-electrode cells' to design microfluidic components, layouts, routing, microfluidic operations and applications of the biochip hierarchically. Fundamental microfluidic operations have been successfully performed by the architecture. In addition, this novel architecture demonstrates a number of advantages and flexibilities over the conventional digital microfluidics in performing advanced microfluidic operations. PMID:22149873

  4. Performance improvements of MOEMS-based diffractive arrays: address isolation and optical switching

    NASA Astrophysics Data System (ADS)

    Panaman, Ganesh; Madison, Seth; Sano, Michael; Castracane, James

    2005-01-01

    Micro-Opto-Electro-Mechanical Systems (MOEMS) have found a variety of applications in fields such as telecommunications, spectroscopy and display technology. MOEMS-based optical switching is currently under investigation for the increased flexibility that such devices provide for reconfiguration of the I/O network for inter-chip communication applications. This potential not only adds an additional degree of freedom for adjustment of transmitter/receiver links but also allows for fine alignment of individual channels in the network link. Further, this use of diffractive arrays for specific applications combines beam steering/adjustment capabilities with the inherent wavelength dependence of the diffractive approach for channel separation and de-multiplexing. Research and development has been concentrated on the progression from single MOEMS components to parallel arrays integrated with optical source arrays for a successful feasibility demonstration. Successful development of such an approach will have a major impact of the next generation communication protocols. This paper will focus on the current status of the MOEMS research program for Free Space Optical inter-chip communication at the College of NanoScale Science and Engineering, University at Albany-SUNY (CNSE). New versions of diffractive arrays stemming from the basic MEMS Compound Grating (MCG; patent #5,999,319) have been produced through various fabrication methods including the MUMPs process1. Most MEMS components relying on electrostatic actuation tend to require high actuation voltages (>20V) compared to the typical 5V levels prevalent in conventional integrated circuits. The specific goal is to yield improved performance while minimizing the power consumption of the components. Structural modifications through the variation in the ruling/electrode spacing distance and array wiring layout through individually addressable gratings have been studied to understand effects on the actuation voltage and

  5. Design and characterisation of a thin-film electrode array with shared reference/counter electrodes for electrochemical detection.

    PubMed

    Uludag, Yildiz; Olcer, Zehra; Sagiroglu, Mahmut Samil

    2014-07-15

    In the current study, a novel electrode array and integrated microfluidics have been designed and characterised in order to create a sensor chip which is not only easy, rapid and cheaper to produce but also have a smaller imprint and good electrochemical sensing properties. The current study includes the assessment of the effects of an Au quasi-reference electrode and the use of shared reference/counter electrodes for the array, in order to obtain a small array that can be produced using a fine metal mask. In the study, it is found that when Au is used as the quasi-reference electrode, the arrays with shared reference and counter electrodes result in faster electron transfer kinetics and prevent the potential change with respect to scan rate, and hence is advantageous with respect to conventional electrodes. In addition, the resulting novel electrode array has been shown to result in higher current density (10.52 µA/cm(2); HRP detection assay) and measured diffusion coefficient (14.40×10(-12) cm(2)/s; calculated from the data of cyclic voltammetry with 1mM potassium ferricyanide) with respect to conventional electrodes tested in the study. Using the new electrode arrays, the detection limits obtained from horse radish peroxidase (HRP) and bisphenol A assays were 12.5 ng/ml (2.84×10(-10) M ) and 10 ng/ml (44×10(-9) M), respectively. Performing the HRP detection assay in a flow injection system using array integrated microfluidics provided 25 times lower detection limit (11.36×10(-12) M), although Ti has been used as electrode material instead of Au. In short, incorporation of this new electrode array to lab-on-a-chip or MEMs (micro-electro mechanic systems) technologies may pave the way for easy to use automated biosensing devices that could be used for a variety of applications from diagnostics to environmental monitoring, and studies will continue to move forward in this direction. PMID:24561521

  6. Light addressable potentiometric sensor with an array of sensing regions

    NASA Astrophysics Data System (ADS)

    Liang, Weiguo; Han, JingHong; Zhang, Hong; Chen, Deyong

    2001-09-01

    This paper describes the mechanism of light addressable poteniometric sensors (LAPS) from the viewpoints of Semiconductor Physics, and introduces the fabrication of a multi-parameter LAPS chip. The MEMS technology is applied to produce a matrix of sensing regions on the wafer. By doing that, the cross talk among these regions is reduced, and the precision of the LAPS is increased. An IR-LED matrix is used as the light source, and the flow-injection method is used to input samples. The sensor system is compact and highly integrated. The measure and control system is composed of a personal computer, a lock-in amplifier, a potentiostat, a singlechip system, and an addressing circuit. Some experiments have been done with this device. The results show that this device is very promising for practical use.

  7. Mapping the temporal pole with a specialized electrode array: technique and preliminary results

    PubMed Central

    Abel, Taylor J.; Rhone, Ariane E.; Nourski, Kirill V.; Granner, Mark A.; Oya, Hiroyuki; Griffiths, Timothy D.; Tranel, Daniel T.; Kawasaki, Hiroto; Howard, Matthew A.

    2014-01-01

    Temporopolar cortex plays a crucial role in the pathogenesis of temporal lobe epilepsy and subserves important cognitive functions. Because of its shape and position in the middle cranial fossa, complete electrode coverage of the temporal pole (TP) is difficult to achieve using existing devices. We designed a novel TP electrode array that conforms to the surface of temporopolar cortex and achieves dense electrode coverage of this important brain region. A multi-pronged electrode array was designed that can be placed over the surface of the TP using a straightforward insertion technique. Twelve patients with medically intractable epilepsy were implanted with the TP electrode array for purposes of seizure localization. Select patients underwent cognitive mapping by electrocorticographic (ECoG) recording from the TP during a naming task. Use of the array resulted in excellent TP electrode coverage in all patients. High quality ECoG data were consistently obtained for purposes of delineating seizure activity and functional mapping. During a naming task, significant increases in ECoG power were observed within localized subregions of the TP. One patient developed a transient neurological deficit thought to be related to the mass effect of multiple intracranial recording arrays, including the TP array. This deficit resolved following removal of all electrodes. The TP electrode array overcomes limitations of existing devices and enables clinicians and researchers to obtain optimal multi-site recordings from this important brain region. PMID:24480831

  8. Cochlear implantation through the round window with a straight slotted electrode array: optimizing the surgical procedure.

    PubMed

    Mom, Thierry; Bachy, Aurélie; Houette, Aubry; Pavier, Yoann; Pastourel, Rémy; Gabrillargues, Jean; Saroul, Nicolas; Gilain, Laurent; Avan, Paul

    2016-04-01

    The question addressed here is how optimizing the quality of insertion through the round window with the lower morbidity, when using a straight and slotted electrode array of regular length. This retrospective analysis includes all cases implanted with a cochlear implant Digisonic SP (Neurelec-Oticon Medical) since 2004. We checked the operative charts, the depth of insertion, and the follow-up. For comparisons, contingency tables were used and a Chi-square test was performed. A p value <0.05 was considered significant. 126 cases of patients with non-malformed cochleas were implanted through the round window. The mean age was 53.8 ± 16.2 for adults and 3.6 ± 2.6 for children (24 cases). The mean follow-up was 33 ± 22 months. The straight electrode array had either a square or a soft pointed tip (n = 84). Full insertion was achieved in 79 out of 84 cases with a soft tip vs. 18 out of 42 square tips (χ (2) = 41.41, DOF = 1, p < 0.0001). Two cases were stuck at the round window niche by a prominent crista fenestrae. In all cases but one, the chorda tympany was preserved. In one case, a misrouting to the vestibule required a revision surgery. Implantation through the round window with a straight and slotted electrode array with a soft tip (Digisonic SP, Neurelec-Oticon Medical) can lead to a full insertion in 94 % of cases. Drilling out a prominent crista fenestrae is recommended. PMID:25894503

  9. Integrated wireless neural interface based on the Utah electrode array.

    PubMed

    Kim, S; Bhandari, R; Klein, M; Negi, S; Rieth, L; Tathireddy, P; Toepper, M; Oppermann, H; Solzbacher, F

    2009-04-01

    This report presents results from research towards a fully integrated, wireless neural interface consisting of a 100-channel microelectrode array, a custom-designed signal processing and telemetry IC, an inductive power receiving coil, and SMD capacitors. An integration concept for such a device was developed, and the materials and methods used to implement this concept were investigated. We developed a multi-level hybrid assembly process that used the Utah Electrode Array (UEA) as a circuit board. The signal processing IC was flip-chip bonded to the UEA using Au/Sn reflow soldering, and included amplifiers for up to 100 channels, signal processing units, an RF transmitter, and a power receiving and clock recovery module. An under bump metallization (UBM) using potentially biocompatible materials was developed and optimized, which consisted of a sputter deposited Ti/Pt/Au thin film stack with layer thicknesses of 50/150/150 nm, respectively. After flip-chip bonding, an underfiller was applied between the IC and the UEA to improve mechanical stability and prevent fluid ingress in in vivo conditions. A planar power receiving coil fabricated by patterning electroplated gold films on polyimide substrates was connected to the IC by using a custom metallized ceramic spacer and SnCu reflow soldering. The SnCu soldering was also used to assemble SMD capacitors on the UEA. The mechanical properties and stability of the optimized interconnections between the UEA and the IC and SMD components were measured. Measurements included the tape tests to evaluate UBM adhesion, shear testing between the Au/Sn solder bumps and the substrate, and accelerated lifetime testing of the long-term stability for the underfiller material coated with a a-SiC(x):H by PECVD, which was intended as a device encapsulation layer. The materials and processes used to generate the integrated neural interface device were found to yield a robust and reliable integrated package. PMID:19067174

  10. Reconfigurable mask for adaptive coded aperture imaging (ACAI) based on an addressable MOEMS microshutter array

    NASA Astrophysics Data System (ADS)

    McNie, Mark E.; Combes, David J.; Smith, Gilbert W.; Price, Nicola; Ridley, Kevin D.; Brunson, Kevin M.; Lewis, Keith L.; Slinger, Chris W.; Rogers, Stanley

    2007-09-01

    Coded aperture imaging has been used for astronomical applications for several years. Typical implementations use a fixed mask pattern and are designed to operate in the X-Ray or gamma ray bands. More recent applications have emerged in the visible and infra red bands for low cost lens-less imaging systems. System studies have shown that considerable advantages in image resolution may accrue from the use of multiple different images of the same scene - requiring a reconfigurable mask. We report on work to develop a novel, reconfigurable mask based on micro-opto-electro-mechanical systems (MOEMS) technology employing interference effects to modulate incident light in the mid-IR band (3-5μm). This is achieved by tuning a large array of asymmetric Fabry-Perot cavities by applying an electrostatic force to adjust the gap between a moveable upper polysilicon mirror plate supported on suspensions and underlying fixed (electrode) layers on a silicon substrate. A key advantage of the modulator technology developed is that it is transmissive and high speed (e.g. 100kHz) - allowing simpler imaging system configurations. It is also realised using a modified standard polysilicon surface micromachining process (i.e. MUMPS-like) that is widely available and hence should have a low production cost in volume. We have developed designs capable of operating across the entire mid-IR band with peak transmissions approaching 100% and high contrast. By using a pixelated array of small mirrors, a large area device comprising individually addressable elements may be realised that allows reconfiguring of the whole mask at speeds in excess of video frame rates.

  11. 4x4 Individually Addressable InGaAs APD Arrays Optimized for Photon Counting Applications

    NASA Technical Reports Server (NTRS)

    Gu, Y.; Wu, X.; Wu, S.; Choa, F. S.; Yan, F.; Shu, P.; Krainak, M.

    2007-01-01

    InGaAs APDs with improved photon counting characteristics were designed and fabricated and their performance improvements were observed. Following the results, a 4x4 individually addressable APD array was designed, fabricated, and results are reported.

  12. USE OF COUPLED MULTI-ELECTRODE ARRAYS TO ADVANCE THE UNDERSTANDING OF SELECTED CORROSION PHENOMENA

    SciTech Connect

    N.D. Budiansky; F. Bocher; H. Cong; M.F. Hurley; J.R. Scully

    2006-02-23

    The use of multi-coupled electrode arrays in various corrosion applications is discussed with the main goal of advancing the understanding of various corrosion phenomena. Both close packed and far spaced electrode configurations are discussed. Far spaced electrode arrays are optimized for high throughput experiments capable of elucidating the effects of various variables on corrosion properties. For instance the effects of a statistical distribution of flaws on corrosion properties can be examined. Close packed arrays enable unprecedented spatial and temporal information on the behavior of local anodes and cathodes. Interactions between corrosion sites can trigger or inhibit corrosion phenomena and affect corrosion damage evolution.

  13. 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

  14. Using multivariate analyses to compare subsets of electrodes and potentials within an electrode array for predicting sugar concentrations in mixed solutions.

    SciTech Connect

    Stork, Christopher Lyle; Steen, William Arthur

    2008-04-01

    A non-selective electrode array is presented for the quantification of fructose, galactose, and glucose in mixed solutions. A unique feature of this electrode array relative to other published work is the wide diversity of electrode materials incorporated within the array, being constructed of 41 different metals and metal alloys. Cyclic voltammograms were acquired for solutions containing a single sugar at varying concentrations, and the correlation between current and sugar concentration was calculated as a function of potential and electrode array element. The correlation plots identified potential regions and electrodes that scaled most linearly with sugar concentration, and the number of electrodes used in building predictive models was reduced to 15. Partial least squares regression models relating electrochemical response to sugar concentration were constructed using data from single electrodes and multiple electrodes within the array, and the predictive abilities of these models were rigorously compared using a non-parametric Wilcoxon test. Models using single electrodes (Pt:Rh (90:10) for fructose, Au:Ni (82:18) for galactose, and Au for glucose) were judged to be statistically superior or indistinguishable from those built with multiple electrodes. Additionally, for each sugar, interval partial least squares regression successfully identified a subset of potentials within a given electrode that generated a model of statistically equivalent predictive ability relative to the full potential model. While including data from multiple electrodes offered no benefit in predicting sugar concentration, use of the array afforded the versatility and flexibility of selecting the best single electrode for each sugar.

  15. A light writable microfluidic "flash memory": optically addressed actuator array with latched operation for microfluidic applications.

    PubMed

    Hua, Zhishan; Pal, Rohit; Srivannavit, Onnop; Burns, Mark A; Gulari, Erdogan

    2008-03-01

    This paper presents a novel optically addressed microactuator array (microfluidic "flash memory") with latched operation. Analogous to the address-data bus mediated memory address protocol in electronics, the microactuator array consists of individual phase-change based actuators addressed by localized heating through focused light patterns (address bus), which can be provided by a modified projector or high power laser pointer. A common pressure manifold (data bus) for the entire array is used to generate large deflections of the phase change actuators in the molten phase. The use of phase change material as the working media enables latched operation of the actuator array. After the initial light "writing" during which the phase is temporarily changed to molten, the actuated status is self-maintained by the solid phase of the actuator without power and pressure inputs. The microfluidic flash memory can be re-configured by a new light illumination pattern and common pressure signal. The proposed approach can achieve actuation of arbitrary units in a large-scale array without the need for complex external equipment such as solenoid valves and electrical modules, which leads to significantly simplified system implementation and compact system size. The proposed work therefore provides a flexible, energy-efficient, and low cost multiplexing solution for microfluidic applications based on physical displacements. As an example, the use of the latched microactuator array as "normally closed" or "normally open" microvalves is demonstrated. The phase-change wax is fully encapsulated and thus immune from contamination issues in fluidic environments. PMID:18305870

  16. Improved spike sorting for multi-electrode array data from mammalian retina

    NASA Astrophysics Data System (ADS)

    Prentice, Jason; Homann, Jan; Simmons, Kristy; Tkacik, Gasper; Balasubramanian, Vijay; Nelson, Philip

    2010-03-01

    Multi-electrode array technology provides an efficient means of simultaneously recording from many neurons. However, as arrays become larger, a greater computational burden falls on the spike-sorting algorithm. We have developed a new method for sorting multi-electrode signals and applied it to retinal ganglion cells. Our method is explicitly designed to scale well with increasing array size. It can dissect temporally overlapping spikes and accommodate the amplitude variation seen in spike bursts. The broad outline of our method is to (1) identify spikes in the raw data, cluster a subset, generate template waveforms, then (2) fit the templates to all the data using an iterative Bayesian algorithm. Each of these two steps makes use of the 2D spatial arrangement of the ganglion cells and electrodes, and the locality of signals from each individual cell. We demonstrate the method on data recorded from guinea pig retina on a 30-electrode array.

  17. Synchronization of neurons in micro-electrode array cultures

    NASA Astrophysics Data System (ADS)

    Esposti, F.; Signorini, M. G.

    2008-12-01

    A lot of methods were created in last decade for the spatio-temporal analysis of multi-electrode array (MEA) neuronal data sets. In this paper we show how a new simple analysis approach that considers the total network activity, is able to show interesting neuronal network system dynamical features. In particular, we perform two different analyses: a neuronal connectivity examination studying networks at different days in vitro (div) and an analysis of the long per- iod effects of the administration of two common neuroactive drugs, Tetrodotoxin (TTX) and D-2-amino-5-phosphonovalerate (AP5), to spontaneously spiking mature neuronal networks. Our analysis is performed considering burst topology, i.e., cataloguing network bursts as Global (if they involve more than the 25% of the MEA channels) or Local (if less that 25%). In the first analysis, this division allows to understand the network connectivity developments. The networking increases from div 1 to 6 building up an undifferentiated highly connected network. From div 6 to 10 the networking decreases (pruning) till reaching a plateau in a small-world like organization. The second analysis highlights substantial differences between long period effects of TTX and AP5. Results show that AP5, selectively blocking NMDA receptors and inhibiting long term potentiation, is unable to produce activity twisting in a network that already reached a developmental plateau, but it is able to desynchronize sub-network (Local) activity. TTX, on the other side, blocking any type of electrical communication among neurons, acts on the whole network synchronization. The important activity increment in the post-TTX epoch (+66%), together with the Global activity explosion, suggests the possibility of a long-term inhibitory-synapse depression mechanism.

  18. 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

  19. A Palladium-Tin Modified Microband Electrode Array for Nitrate Determination.

    PubMed

    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

  20. Electrodeposition of gold nanoparticle arrays on ITO glass as electrode with high electrocatalytic activity

    SciTech Connect

    Zhang, Kui; Wei, Juan; Zhu, Houjuan; Ma, Fang; Wang, Suhua

    2013-03-15

    Highlights: ► Electrodeposition of gold nanoparticle arrays on ITO glass as catalytic-electrodes. ► The sizes and densities of the gold nanoparticles can be easily controlled. ► Such arrays on ITO glass shows high electrocatalytic activity and good stability. - Abstract: Herein, we reported a templateless, surfactantless, and simple electrochemical method to directly fabricate gold nanoparticle (AuNP) arrays on indium tin oxide (ITO) glass substrates as effective electrocatalytic electrodes. The as-prepared AuNP arrays have been characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), etc. AuNPs with small sizes (<20 nm) were uniformly deposited on the ITO glass under constant current densities, and particle densities can be adjusted by varying the applied charges. The resultant AuNP array electrode showed higher catalytic activity and good stability toward electro-oxidation of ascorbic acid compared with other electrodes, such as bare ITO electrode, bare glassy carbon electrode and bulk gold film electrode.

  1. 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. PMID:25681972

  2. An Ultralong, Highly Oriented Nickel-Nanowire-Array Electrode Scaffold for High-Performance Compressible Pseudocapacitors.

    PubMed

    Xu, Chao; Li, Ziheng; Yang, Cheng; Zou, Peichao; Xie, Binghe; Lin, Ziyin; Zhang, Zhexu; Li, Baohua; Kang, Feiyu; Wong, Ching-Ping

    2016-06-01

    Ultralong, highly oriented Ni nanowire arrays are used as the electrode scaffold to support metal-oxide- and conductive-polymer-based electrode materials with a high mass loading; the as-obtained asymmetric supercapacitor can be compressed by fourfold and exhibits superior energy and power densities with ultrahigh cycle stability. PMID:27062285

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

    PubMed Central

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

    2015-01-01

    Background: 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. Methods: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. Results: 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. Conclusions: 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

  4. Shaping of steel mold surface of lens array by electrical discharge machining with single rod electrode.

    PubMed

    Takino, Hideo; Hosaka, Takahiro

    2014-11-20

    We propose a method for fabricating a lens array mold by electrical discharge machining (EDM). In this method, the tips of rods are machined individually to form a specific surface, and then a number of the machined rods are arranged to construct an electrode for EDM. The repetition of the EDM process using the electrode enables a number of lens elements to be produced on the mold surface. The effectiveness of our proposed method is demonstrated by shaping a lens array mold made of stainless steel with 16 spherical elements, in which the EDM process with a single rod electrode is repeatedly conducted. PMID:25607880

  5. A Novel Method of Fabricating Convoluted Shaped Electrode Arrays for Neural and Retinal Prostheses

    PubMed Central

    Bhandari, R.; Negi, S.; Rieth, L.; Normann, R. A.; Solzbacher, F.

    2008-01-01

    A novel fabrication technique has been developed for creating high density (6.25 electrodes/mm2), out of plane, high aspect ratio silicon-based convoluted microelectrode arrays for neural and retinal prostheses. The convoluted shape of the surface defined by the tips of the electrodes could compliment the curved surfaces of peripheral nerves and the cortex, and in the case of retina, its spherical geometry. The geometry of these electrode arrays has the potential to facilitate implantation in the nerve fascicles and to physically stabilize it against displacement after insertion. This report presents a unique combination of variable depth dicing and wet isotropic etching for the fabrication of a variety of convoluted neural array geometries. Also, a method of deinsulating the electrode tips using photoresist as a mask and the limitations of this technique on uniformity are discussed. PMID:19122774

  6. Mass transport at infinite regular arrays of microband electrodes submitted to natural convection: theory and experiments.

    PubMed

    Pebay, Cécile; Sella, Catherine; Thouin, Laurent; Amatore, Christian

    2013-12-17

    Mass transport at infinite regular arrays of microband electrodes was investigated theoretically and experimentally in unstirred solutions. Even in the absence of forced hydrodynamics, natural convection limits the convection-free domain up to which diffusion layers may expand. Hence, several regimes of mass transport may take place according to the electrode size, gap between electrodes, time scale of the experiment, and amplitude of natural convection. They were identified through simulation by establishing zone diagrams that allowed all relative contributions to mass transport to be delineated. Dynamic and steady-state regimes were compared to those achieved at single microband electrodes. These results were validated experimentally by monitoring the chronoamperometric responses of arrays with different ratios of electrode width to gap distance and by mapping steady-state concentration profiles above their surface through scanning electrochemical microscopy. PMID:24283775

  7. Shaping of steel mold surface of lens array by electrical discharge machining with spherical ball electrode.

    PubMed

    Takino, Hideo; Hosaka, Takahiro

    2016-06-20

    We propose a method for fabricating a spherical lens array mold by electrical discharge machining (EDM) with a ball-type electrode. The electrode is constructed by arranging conductive spherical balls in an array. To fundamentally examine the applicability of the proposed EDM method to the fabrication of lens array molds, we use an electrode having a single ball to shape a lens array mold made of stainless steel with 16 spherical elements, each having a maximum depth of 0.5 mm. As a result, a mold surface is successfully shaped with a peak-to-valley shape accuracy of approximately 10 μm, and an average surface roughness of 0.85 μm. PMID:27409126

  8. 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.

  9. A MEMS fabricated flexible electrode array for recording surface field potentials.

    PubMed

    Hollenberg, Brian A; Richards, Cecilia D; Richards, Robert; Bahr, David F; Rector, David M

    2006-05-15

    We developed a method to microfabricate flexible electrode arrays on a thin Kapton substrate, which was engineered to minimize trauma when inserted between the dura and skull to obtain surface EEG recordings. The array consisted of 64 gold electrodes, each 150microm in diameter on a 750microm spaced 8x8 grid. Using photolithographic procedures, any arrangement of electrodes can be implemented. We used the electrode array to record evoked response signals to create topographical maps of the whisker barrels on the cortical surface with excellent signal stability over a period of 8h. The materials used for this fabrication are potentially biologically inert and, with some additional modifications to the design, can be chronically implanted with minimal side effects. Retinal prosthesis, human neurosurgery, and neurological research are all limited to some degree by the resolution and biological compatibility of the implants used. This type of array could greatly enhance the spatial resolution, signal quality, and stability of implantable surface electrode arrays. PMID:16352343

  10. 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

  11. Cochleotopic selectivity of a multichannel scala tympani electrode array using the 2-deoxyglucose technique.

    PubMed

    Brown, M; Shepherd, R K; Webster, W R; Martin, R L; Clark, G M

    1992-05-01

    The 2-deoxyglucose (2-DG) technique was used to study the cochleotopic selectivity of a multichannel scala tympani electrode array in four cats with another acting as an unstimulated control. Each animal was unilaterally deafened and a multichannel electrode array inserted 6 mm into the scala tympani. Thresholds to electrical stimulation were determined by recording electrically evoked auditory brainstem responses (EABRs). Each animal was injected with 2-DG, and electrically stimulated using bipolar electrodes located either distal or proximal to the round window. The contralateral ear was stimulated with acoustic tone pips at frequencies that matched the electrode place. Stimulation of both distal and proximal bipolar electrodes at 3 x EABR threshold, evoked localized 2-DG labelling in both ipsilateral cochlear nucleus (CN) and the contralateral inferior colliculus (IC), which was very similar in orientation and breadth to labelling evoked by the contralateral tone pips. The cochleotopic position of labelling to proximal stimulation was located in the 24-26 kHz region of each structure, whereas the distal labelling was located around 12 kHz. Distal stimulation at 10 x EABR threshold produced very broad 2-DG labelling in IC centered around the 12 kHz place. The present 2-DG results clearly illustrate cochleotopic selectivity using multichannel bipolar scala tympani electrodes. The extent of this selectivity is dependent on electrical stimulus levels. The 2-DG technique has great potential in evaluating the efficacy of new electrode array designs. PMID:1618713

  12. Optimized arrays for 2-D resistivity survey lines with a large number of electrodes

    NASA Astrophysics Data System (ADS)

    Loke, M. H.; Wilkinson, P. B.; Chambers, J. E.; Uhlemann, S. S.; Sorensen, J. P. R.

    2015-01-01

    Previous studies show that optimized arrays generated using the 'Compare R' method have significantly better resolution than conventional arrays. This method determines the optimum set of arrays by selecting those that give the maximum model resolution. The number of possible arrays (the comprehensive data set) increases with the fourth power of the number of electrodes. The optimization method faces practical limitations for 2-D survey lines with more than 60 electrodes where the number of possible arrays exceeds a million. Several techniques are proposed to reduce the calculation time for such survey lines. A single-precision version of the 'Compare R' algorithm using a new ranking function reduces the calculation time by two to eight times while providing results similar to the double-precision version. Recent improvements in computer GPU technology can reduce the calculation time by about seven times. The calculation time is reduced by half by using the fact that arrays that are symmetrical about the center of the line produce identical changes in the model resolution values. It is further reduced by more than thirty times by calculating the Sherman-Morrison update for all the possible two-electrode combinations, which are then used to calculate the model resolution values for the four-electrode arrays. The calculation time is reduced by more then ten times by using a subset of the comprehensive data set consisting of only symmetrical arrays. Tests with a synthetic model and field data set show that optimized arrays derived from this subset produce inversion models with differences of less than 10% from those derived using the full comprehensive data set. The optimized data sets produced models that are more accurate than the Wenner-Schlumberger array data sets in all the tests.

  13. 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. PMID:10188608

  14. Advancements in electrode design and laser techniques for fabricating micro-electrode arrays as part of a retinal prosthesis.

    PubMed

    Dodds, C W D; Schuettler, M; Guenther, T; Lovell, N H; Suaning, G J

    2011-01-01

    Retinal micro-electrode arrays (MEAs) for a visual prosthesis were fabricated by laser structuring of platinum (Pt) foil and liquid silicone rubber. A new design was created using a folding technique to create a multi-layered array from a single Pt sheet. This method allowed a reduction in both the electrode pitch, and the overall width of the array, while maintaining coplanar connection points for more stable interconnections to other components of the system. The design also included a section which could be rolled to create a cylindrical segment in order to minimise the size of the exit in the sclera after implantation. A picosecond mode-locked 532 nm laser system was investigated as a replacement for the nanosecond Q-switched 1064 nm laser currently in use. Trials showed that the ps system could produce high quality electrode tracks with a minimum pitch of 30 μm, less than 40% the pitch achievable with the ns laser. A method was investigated for the cutting of Pt foils without damaging the underlying silicone by laser machining to a depth just below the thickness of the foil. Initial samples showed promise with full penetration of the foil only occurring at cross points of the laser paths. The ps laser was also used to create roughened surfaces, in order to increase the electrochemical surface area of the electrodes. Surfaces were imaged using a scanning electron microscope, and compared to surfaces roughened with the ns laser. The ps laser was seen to offer a reduction in feature size, as well as an increase in control over the appearance of the electrode surface. PMID:22254389

  15. An integrated multi-electrode-optrode array for in vitro optogenetics

    PubMed Central

    Welkenhuysen, Marleen; Hoffman, Luis; Luo, Zhengxiang; De Proft, Anabel; Van den Haute, Chris; Baekelandt, Veerle; Debyser, Zeger; Gielen, Georges; Puers, Robert; Braeken, Dries

    2016-01-01

    Modulation of a group of cells or tissue needs to be very precise in order to exercise effective control over the cell population under investigation. Optogenetic tools have already demonstrated to be of great value in the study of neuronal circuits and in neuromodulation. Ideally, they should permit very accurate resolution, preferably down to the single cell level. Further, to address a spatially distributed sample, independently addressable multiple optical outputs should be present. In current techniques, at least one of these requirements is not fulfilled. In addition to this, it is interesting to directly monitor feedback of the modulation by electrical registration of the activity of the stimulated cells. Here, we present the fabrication and characterization of a fully integrated silicon-based multi-electrode-optrode array (MEOA) for in vitro optogenetics. We demonstrate that this device allows for artifact-free electrical recording. Moreover, the MEOA was used to reliably elicit spiking activity from ChR2-transduced neurons. Thanks to the single cell resolution stimulation capability, we could determine spatial and temporal activation patterns and spike latencies of the neuronal network. This integrated approach to multi-site combined optical stimulation and electrical recording significantly advances today’s tool set for neuroscientists in their search to unravel neuronal network dynamics. PMID:26832455

  16. An Electrode Array for Limiting Blood Loss During Liver Resection: Optimization via Mathematical Modeling

    PubMed Central

    Strigel, R.M.; Schutt, D.J.; Webster, J.G.; Mahvi, D.M.; Haemmerich, D.

    2010-01-01

    Liver resection is the current standard treatment for patients with both primary and metastatic liver cancer. The principal causes of morbidity and mortality after liver resection are related to blood loss (typically between 0.5 and 1 L), especially in cases where transfusion is required. Blood transfusions have been correlated with decreased long-term survival, increased risk of perioperative mortality and complications. The goal of this study was to evaluate different designs of a radiofrequency (RF) electrode array for use during liver resection. The purpose of this electrode array is to coagulate a slice of tissue including large vessels before resecting along that plane, thereby significantly reducing blood loss. Finite Element Method models were created to evaluate monopolar and bipolar power application, needle and blade shaped electrodes, as well as different electrode distances. Electric current density, temperature distribution, and coagulation zone sizes were measured. The best performance was achieved with a design of blade shaped electrodes (5 × 0.1 mm cross section) spaced 1.5 cm apart. The electrodes have power applied in bipolar mode to two adjacent electrodes, then switched sequentially in short intervals between electrode pairs to rapidly heat the tissue slice. This device produces a ~1.5 cm wide coagulation zone, with temperatures over 97 ºC throughout the tissue slice within 3 min, and may facilitate coagulation of large vessels. PMID:20309395

  17. 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

  18. 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

    2015-01-01

    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

  19. Thermal management of quantum cascade lasers in an individually addressable monolithic array architecture

    NASA Astrophysics Data System (ADS)

    Missaggia, Leo; Wang, Christine; Connors, Michael; Saar, Brian; Sanchez-Rubio, Antonio; Creedon, Kevin; Turner, George; Herzog, William

    2016-03-01

    There are a number of military and commercial applications for high-power laser systems in the mid-to-long-infrared wavelength range. By virtue of their demonstrated watt-level performance and wavelength diversity, quantum cascade laser (QCL) and amplifier devices are an excellent choice of emitter for those applications. To realize the power levels of interest, beam combining of arrays of these emitters is required and as a result, array technology must be developed. With this in mind, packaging and thermal management strategies were developed to facilitate the demonstration of a monolithic QCL array operating under CW conditions. Thermal models were constructed and simulations performed to determine the effect of parameters such as array-element ridge width and pitch on gain region temperature rise. The results of the simulations were considered in determining an appropriate QCL array configuration. State-of-the-art micro-impingement cooling along with an electrical distribution scheme comprised of AlN multi-layer technology were integrated into the design. The design of the module allows for individual electrical addressability of the array elements, a method of phase control demonstrated previously for coherent beam combining of diode arrays, along with access to both front and rear facets. Hence, both laser and single-pass amplifier arrays can be accommodated. A module was realized containing a 5 mm cavity length monolithic QCL array comprised of 7 elements on 450 m pitch. An output power of 3.16 W was demonstrated under CW conditions at an emission wavelength of 9μm.

  20. A top-crossover-to-bottom addressed segmented annular array using piezoelectric micromachined ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Jung, Joontaek; Lee, Wonjun; Kang, Woojin; Hong, Hyeryung; Yuen Song, Hi; Oh, Inn-yeal; Park, Chul Soon; Choi, Hongsoo

    2015-11-01

    We design and fabricate segmented annular arrays (SAAs) using piezoelectric micromachined ultrasonic transducers (pMUTs) to demonstrate the feasibility of acoustic focusing of ultrasound. The fabricated SAAs have 25 concentric top-electrode signal lines and eight bottom-electrodes for grounding to enable electronic steering of selectively grouped ultrasonic transducers from 2393 pMUT elements. Each element in the array is connected by top-crossover-to-bottom metal bridges, which reduce the parasitic capacitance. Circular-shaped pMUT elements, 120 μm in diameter, are fabricated using 1 μm-thick sol-gel lead zirconate titanate on a silicon wafer. To utilize the high-density pMUT array, a deep reactive ion etching process is used for anisotropic silicon etching to realize the transducer membranes. The resonant frequency and effective coupling coefficient of the elements, measured with an impedance analyzer, yields 1.517 MHz and 1.29%, respectively, in air. The SAAs using pMUTs are packaged on a printed circuit board and coated with parylene C for acoustic intensity measurements in water. The ultrasound generated by each segmented array is focused on a selected point in space. When a 5 Vpp, 1.5 MHz square wave is applied, the maximum spatial peak temporal average intensity ({{I}\\text{spta}} ) is found to be 79 mW cm-2 5 mm from the SAAs’ surface without beamforming. The beam widths (-3 dB) of ultrasonic radiation patterns in the elevation and azimuth directions are recorded as 3 and 3.4 mm, respectively. The results successfully show the feasibility of focusing ultrasound on a small area with SAAs using pMUTs.

  1. Addressable nanowell arrays formed using reversibly sealable hybrid elastomer-metal stencils.

    PubMed

    Pla-Roca, Mateu; Leulmi, Rym Feriel; Djambazian, Haig; Sundararajan, Saravanan; Juncker, David

    2010-05-01

    There are two major array formats used in life science research and biomedical analysis. The first is the microwell plate format with millimeter-sized wells each with microliter capacity addressed individually and repeatedly during experiments. The second is the microarray format with micrometer-sized spots that are patterned initially but not addressable individually thereafter. Here, we present an addressable nanoliter-well plate with micrometer sized wells that combines the advantages of the two array formats. The nanowells are formed by reversibly sealing a steel stencil featuring an array of micrometer-scale openings to an optically transparent substrate. The nanowells have a capacity of approximately 1 nL, are approximately 140 microm in diameter, and are arrayed at a density of 1600 wells cm(-2). A soft polymer is patterned photolithographically around each opening so as to form a microgasket for pressure sensitive, liquid tight, and reversible sealing to any type of smooth substrate, either hydrophilic or hydrophobic. The rigidity of the steel prevents the distortion that occurs in soft, all-polymeric stencils and permits accurate registration across the entire array, which in turn allows for repeated, individual addressing of wells using an inkjet spotter. The stencils are used to pattern cells, make protein microarrays, and create nanowells on surfaces to study reverse transfection by first spotting plasmids encoding fluorescent proteins into the wells, seeding cells, and monitoring the transfection of the cells in real time using time-lapse imaging. The hybrid elastomer-metal stencils (HEMSs) are versatile and useful for multiplexed analysis of drugs, biomolecules, and cells with microarray density. PMID:20377190

  2. Three-dimensional micro-electrode array for recording dissociated neuronal cultures.

    PubMed

    Musick, Katherine; Khatami, David; Wheeler, Bruce C

    2009-07-21

    This work demonstrates the design, fabrication, packaging, characterization, and functionality of an electrically and fluidically active three-dimensional micro-electrode array (3D MEA) for use with neuronal cell cultures. The successful function of the device implies that this basic concept-construction of a 3D array with a layered approach-can be utilized as the basis for a new family of neural electrode arrays. The 3D MEA prototype consists of a stack of individually patterned thin films that form a cell chamber conducive to maintaining and recording the electrical activity of a long-term three-dimensional network of rat cortical neurons. Silicon electrode layers contain a polymer grid for neural branching, growth, and network formation. Along the walls of these electrode layers lie exposed gold electrodes which permit recording and stimulation of the neuronal electrical activity. Silicone elastomer micro-fluidic layers provide a means for loading dissociated neurons into the structure and serve as the artificial vasculature for nutrient supply and aeration. The fluidic layers also serve as insulation for the micro-electrodes. Cells have been shown to survive in the 3D MEA for up to 28 days, with spontaneous and evoked electrical recordings performed in that time. The micro-fluidic capability was demonstrated by flowing in the drug tetrotodoxin to influence the activity of the culture. PMID:19568672

  3. A New Individually Addressable Micro-LED Array for Photogenetic Neural Stimulation.

    PubMed

    McGovern, B; Berlinguer Palmini, R; Grossman, N; Drakakis, E; Poher, V; Neil, M A A; Degenaar, P

    2010-12-01

    Here, we demonstrate the use of a micro light emitting diode (LED) array as a powerful tool for complex spatiotemporal control of photosensitized neurons. The array can generate arbitrary, 2-D, excitation patterns with millisecond and micrometer resolution. In particular, we describe an active matrix control address system to allow simultaneous control of 256 individual micro LEDs. We present the system optically integrated into a microscope environment and patch clamp electrophysiology. The results show that the emitters have sufficient radiance at the required wavelength to stimulate neurons expressing channelrhodopsin-2 (ChR2). PMID:23853385

  4. An array of individually addressable micro-needles for mapping pH distributions.

    PubMed

    Zuliani, Claudio; Ng, Fu Siong; Alenda, Andrea; Eftekhar, Amir; Peters, Nicholas S; Toumazou, Christofer

    2016-08-01

    This work describes the preparation of an array of individually addressable pH sensitive microneedles which are sensitized by electrodepositing iridium oxide. The impact of the deposition potential, storage conditions and interferents on the sensor characteristics such as slope, offset, intra- and inter-batch reproducibility is investigated. The device may be a useful tool for carrying out direct pH measurements of soft and heterogeneous samples such as tissues and organs. For example, we demonstrated that the microneedle array can be employed for real-time mapping of the cardiac pH distribution during cycles of global ischemia and reperfusion. PMID:27243147

  5. Microfabrication of electrode patterns for high-frequency ultrasound transducer arrays.

    PubMed

    Bernassau, Anne L; García-Gancedo, Luis; Hutson, David; Démoré, Christine E M; McAneny, Jim J; Button, Tim W; Cochran, Sandy

    2012-08-01

    High-frequency ultrasound is needed for medical imaging with high spatial resolution. A key issue in the development of ultrasound imaging arrays to operate at high frequencies (≥30 MHz) is the need for photolithographic patterning of array electrodes. To achieve this directly on 1-3 piezocomposite, the material requires not only planar, parallel, and smooth surfaces, but also an epoxy composite filler that is resistant to chemicals, heat, and vacuum. This paper reports, first, on the surface finishing of 1-3 piezocomposite materials by lapping and polishing. Excellent surface flatness has been obtained, with an average surface roughness of materials as low as 3 nm and step heights between ceramic/polymer of ∼80 nm. Subsequently, high-frequency array elements were patterned directly on top of these surfaces using a photolithography process. A 30-MHz linear array electrode pattern with 50-μm element pitch has been patterned on the lapped and polished surface of a high-frequency 1-3 piezocomposite. Excellent electrode edge definition and electrical contact to the composite were obtained. The composite has been lapped to a final thickness of ∼55 μm. Good adhesion of electrodes on the piezocomposite has been achieved and electrical impedance measurements have demonstrated their basic functionality. The array was then packaged, and acoustic pulse-echo measurements were performed. These results demonstrate that direct patterning of electrodes by photolithography on 1-3 piezocomposite is feasible for fabrication of high-frequency ultrasound arrays. Furthermore, this method is more conducive to mass production than other reported array fabrication techniques. PMID:22899129

  6. Orthogonal electrode catheter array for mapping of endocardial focal site of ventricular activation

    SciTech Connect

    Desai, J.M.; Nyo, H.; Vera, Z.; Seibert, J.A.; Vogelsang, P.J. )

    1991-04-01

    Precise location of the endocardial site of origin of ventricular tachycardia may facilitate surgical and catheter ablation of this arrhythmia. The endocardial catheter mapping technique can locate the site of ventricular tachycardia within 4-8 cm2 of the earliest site recorded by the catheter. This report describes an orthogonal electrode catheter array (OECA) for mapping and radiofrequency ablation (RFA) of endocardial focal site of origin of a plunge electrode paced model of ventricular activation in dogs. The OECA is an 8 F five pole catheter with four peripheral electrodes and one central electrode (total surface area 0.8 cm{sup 2}). In eight mongrel dogs, mapping was performed by arbitrarily dividing the left ventricle (LV) into four segments. Each segment was mapped with OECA to find the earliest segment. Bipolar and unipolar electrograms were obtained. The plunge electrode (not visible on fluoroscopy) site was identified by the earliest wave front arrival times of -30 msec or earlier at two or more electrodes (unipolar electrograms) with reference to the earliest recorded surface ECG (I, AVF, and V1). Validation of the proximity of the five electrodes of the OECA to the plunge electrode was performed by digital radiography and RFA. Pathological examination was performed to document the proximity of the OECA to the plunge electrode and also for the width, depth, and microscopic changes of the ablation. To find the segment with the earliest LV activation a total of 10 {plus minus} 3 (mean {plus minus} SD) positions were mapped. Mean arrival times at the two earlier electrodes were -39 {plus minus} 4 msec and -35 {plus minus} 3 msec. Digital radiography showed the plunge electrode to be within the area covered by all five electrodes in all eight dogs. The plunge electrode was within 1 cm2 area of the region of RFA in all eight dogs.

  7. Arrayed liquid crystal microlens based on graphene electrode for imaging application

    NASA Astrophysics Data System (ADS)

    Hu, Wei; Chen, Cheng; Wu, Yong; Luo, Jun; Lei, Yu; Tong, Qing; Zhang, Xinyu; Xie, Changsheng

    2015-10-01

    In this paper, an arrayed liquid crystal (LC) microlens (ALCM) based on graphene electrode instead of common indium tin oxide (ITO) electrode material is designed and fabricated, and the corresponding testing results have been obtained and presented. The graphene film used as patterned electrode in the project is grown by chemical vapor deposition (CVD) over copper foils, which demonstrate the properties of low sheet resistance and high transmittance of more than 90% in current stage. The key fabrication of the arrayed LC microlens based on graphene electrode includes the graphene transfering, ultraviolet lithography, ICP etching, liquid crystalline polymer encapsulation, etc. In the test of the arrayed LC microlens, the point spread functions (PSF) of incident laser beams with different wavelengths, such as red laser of ~600nm wavelength, and green laser of ~532nm wavelength, have been obtained. In addition, the arrayed LC microlenses are also used in visible light imaging. During the imaging tests, each microlens in the arrayed LC microlens can perform imaging process, independently.

  8. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    SciTech Connect

    Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W.; Na, J.; Kim, G. T.; Lee, B. J.; Kim, J. J.; Jeong, G. H.; Lee, I.; Kim, K. S.

    2015-07-20

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

  9. Fabrication of comb interdigitated electrodes array (IDA) for a microbead-based electrochemical assay system.

    PubMed

    Kim, Sang Kyung; Hesketh, Peter J; Li, Changming; Thomas, Jennifer H; Halsall, H Brian; Heineman, William R

    2004-11-01

    This research is directed towards developing a more sensitive and rapid electrochemical sensor for enzyme labeled immunoassays by coupling redox cycling at interdigitated electrode arrays (IDA) with the enzyme label beta-galactosidase. Coplanar and comb IDA electrodes with a 2.4 microm gap were fabricated and their redox cycling currents were measured. ANSYS was used to model steady state currents for electrodes with different geometries. Comb IDA electrodes enhanced the signal about three times more than the coplanar IDAs, which agreed with the results of the simulation. Magnetic microbead-based enzyme assay, as a typical example of biochemical detection, was done using the comb and coplanar IDAs. The enzymes could be placed close to the sensing electrodes (approximately 10 microm for the comb IDAs) and detection took less than 1 min with a limit of detection of 70 amol of beta-galactosidase. We conclude that faster and more sensitive assays can be achieved with the comb IDA. PMID:15522606

  10. Controllable in-situ cell electroporation with cell positioning and impedance monitoring using micro electrode array

    PubMed Central

    Guo, Xiaoliang; Zhu, Rong

    2016-01-01

    This paper reports a novel microarray chip for in-situ, real-time and selective electroporation on individual cells integrated with cell positioning and impedance monitoring. An array of quadrupole-electrode units (termed positioning electrodes) and pairs of planar center electrodes located at the centers of each quadrupole-electrode unit were fabricated on the chip. The positioning electrodes are used to trap and position living cells onto the center electrodes based on negative dielectrophoresis (nDEP). The center electrodes are used for in-situ cell electroporation, and also used to measure cell impedance for monitoring cellular dynamics in real time. Controllably selective electroporation and electrical measurement on the cells in array are realized. We present an evidence of selective electroporation through use of fluorescent dyes. Subsequently we use in-situ and real-time impedance measurement to monitor the process, which demonstrates the dynamic behavior of the cell electroporation. Finally, we show the use of this device to perform successful transfection onto individual HeLa cells with vector DNA encoding a green fluorescent. PMID:27507603

  11. Controllable in-situ cell electroporation with cell positioning and impedance monitoring using micro electrode array.

    PubMed

    Guo, Xiaoliang; Zhu, Rong

    2016-01-01

    This paper reports a novel microarray chip for in-situ, real-time and selective electroporation on individual cells integrated with cell positioning and impedance monitoring. An array of quadrupole-electrode units (termed positioning electrodes) and pairs of planar center electrodes located at the centers of each quadrupole-electrode unit were fabricated on the chip. The positioning electrodes are used to trap and position living cells onto the center electrodes based on negative dielectrophoresis (nDEP). The center electrodes are used for in-situ cell electroporation, and also used to measure cell impedance for monitoring cellular dynamics in real time. Controllably selective electroporation and electrical measurement on the cells in array are realized. We present an evidence of selective electroporation through use of fluorescent dyes. Subsequently we use in-situ and real-time impedance measurement to monitor the process, which demonstrates the dynamic behavior of the cell electroporation. Finally, we show the use of this device to perform successful transfection onto individual HeLa cells with vector DNA encoding a green fluorescent. PMID:27507603

  12. Electrical stimulation with a penetrating optic nerve electrode array elicits visuotopic cortical responses in cats

    NASA Astrophysics Data System (ADS)

    Lu, Yiliang; Yan, Yan; Chai, Xinyu; Ren, Qiushi; Chen, Yao; Li, Liming

    2013-06-01

    Objective. A visual prosthesis based on penetrating electrode stimulation within the optic nerve (ON) is a potential way to restore partial functional vision for blind patients. We investigated the retinotopic organization of ON stimulation and its spatial resolution. Approach. A five-electrode array was inserted perpendicularly into the ON or a single electrode was advanced to different depths within the ON (˜1-2 mm behind the eyeball, 13 cats). A sparse noise method was used to map ON electrode position and the visual cortex. Cortical responses were recorded by a 5 × 6 array. The visuotopic correspondence between the retinotopic position of the ON electrode was compared with the visual evoked cortical map and the electrical evoked potentials elicited in response to ON stimulation. Main results. Electrical stimulation with penetrating ON electrodes elicited cortical responses in visuotopographically corresponding areas of the cortex. Stimulation of the temporal side of the ON elicited cortical responses corresponding to the central visual field. The visual field position shifted from the lower to central visual field as the electrode penetrated through the depth of the ON. A spatial resolution of ˜ 2° to 3° within a limited cortical visuotopic representation could be obtained by this approach. Significance. Visuotopic electrical stimulation with a relatively fine spatial resolution can be accomplished using penetrating electrodes implanted at multiple sites and at different depths within the ON just behind the globe. This study also provides useful experimental data for the design of electrode density and the distribution of penetrating ON electrodes for a visual prosthesis.

  13. Flexible active electrode arrays with ASICs that fit inside the rat's spinal canal.

    PubMed

    Giagka, Vasiliki; Demosthenous, Andreas; Donaldson, Nick

    2015-12-01

    Epidural spinal cord electrical stimulation (ESCS) has been used as a means to facilitate locomotor recovery in spinal cord injured humans. Electrode arrays, instead of conventional pairs of electrodes, are necessary to investigate the effect of ESCS at different sites. These usually require a large number of implanted wires, which could lead to infections. This paper presents the design, fabrication and evaluation of a novel flexible active array for ESCS in rats. Three small (1.7 mm(2)) and thin (100 μm) application specific integrated circuits (ASICs) are embedded in the polydimethylsiloxane-based implant. This arrangement limits the number of communication tracks to three, while ensuring maximum testing versatility by providing independent access to all 12 electrodes in any configuration. Laser-patterned platinum-iridium foil forms the implant's conductive tracks and electrodes. Double rivet bonds were employed for the dice microassembly. The active electrode array can deliver current pulses (up to 1 mA, 100 pulses per second) and supports interleaved stimulation with independent control of the stimulus parameters for each pulse. The stimulation timing and pulse duration are very versatile. The array was electrically characterized through impedance spectroscopy and voltage transient recordings. A prototype was tested for long term mechanical reliability when subjected to continuous bending. The results revealed no track or bond failure. To the best of the authors' knowledge, this is the first time that flexible active electrode arrays with embedded electronics suitable for implantation inside the rat's spinal canal have been proposed, developed and tested in vitro. PMID:26466839

  14. Multi-electrode array technologies for neuroscience and cardiology

    NASA Astrophysics Data System (ADS)

    Spira, Micha E.; Hai, Aviad

    2013-02-01

    At present, the prime methodology for studying neuronal circuit-connectivity, physiology and pathology under in vitro or in vivo conditions is by using substrate-integrated microelectrode arrays. Although this methodology permits simultaneous, cell-non-invasive, long-term recordings of extracellular field potentials generated by action potentials, it is 'blind' to subthreshold synaptic potentials generated by single cells. On the other hand, intracellular recordings of the full electrophysiological repertoire (subthreshold synaptic potentials, membrane oscillations and action potentials) are, at present, obtained only by sharp or patch microelectrodes. These, however, are limited to single cells at a time and for short durations. Recently a number of laboratories began to merge the advantages of extracellular microelectrode arrays and intracellular microelectrodes. This Review describes the novel approaches, identifying their strengths and limitations from the point of view of the end users -- with the intention to help steer the bioengineering efforts towards the needs of brain-circuit research.

  15. Electrothermal flow on electrodes arrays at physiological conductivities.

    PubMed

    Koklu, Anil; Tansel, Osman; Oksuzoglu, Hakan; Sabuncu, Ahmet C

    2016-04-01

    AC electrothermal (ET) flow is inevitable for microfluidic systems dissipating electric energy in a conducting medium. Therefore, many practical applications of biomicrofluidics are prone to ET flow. Here, a series of observations are reported on ET flow in a microfluidic chamber that houses three electrode pairs. The observations indicate that the variations in liquid conductivity and channel height critically impact the structure and magnitude of the flow field. Observations indicate that after a critical conductivity a global ET flow is present in the chamber, while at lower conductivities a vortex is present at every electrode edge. In addition, no ET flow is observed when the chamber height is kept below a critical value at physiological conductivity (∼1.5 S/m). The experimental observations are compared with the numerical simulations of ET flow. The validity of the assumptions made in the current AC ET flow theory is also discussed in the light of the experimental data. The observations can be critical while designing microfluidic systems that involve power dissipation in conductive fluids. PMID:27074854

  16. 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. PMID:25748997

  17. Study on Fabrication and UV Photoelectric Property of TiO2 Nanotube Array Electrodes.

    PubMed

    Fu, Yao; Duan, Xiao-Long; Xing, Ming-Ming; Luo, Xi-Xian; Zhang, Ying-Hui; Liu, Wang

    2016-04-01

    Highly ordered TiO2 nanotube array electrodes were successfully fabricated by a two-step anodization method on Ti sheet substrates in an electrolyte composed of ammonium fluoride, deionized water, and glycol. The tube wall was smooth, and the average internal and external diameters, wall thickness, and tube length achieved were 80 nm, 90 nm, 10 nm, and 9 µm, respectively. X-ray diffraction and field emission scanning electron microscopy results revealed that the TiO2 nanotube arrays presented an amorphous structure. When calcined at 300 °C, the arrays crystallized into the anatase phase, and the crystallization degree of the oxide layer increased as the temperature rose. Calcinating at 400 °C did not obviously disrupt the porous structure of the highly ordered arrays. However, higher temperature enlarged the diameter of the nanotube array and roughened the tube wall. When the temperature reached 600 °C, the nanotube mouth broke because of the excessive stress, causing the oxide layer's thinness and nanotube mouth clogging. The photoelectric test showed that the electrode presented obvious photoresponse under 300-400 nm UV excitation (maximized at 360 nm). The degree of crystallization and the micro-structure of the oxide layer can significantly affect the photoelectric properties of the electrode. After calcination at 400 °C, the TiO2 nanotube arrays, with highly ordered tubular structure directly connected to the Ti substrate, can ensure the rapid transportation of photo-induced electrons to the Ti substrate, while the high crystallinity of the arrays can help reduce the defect density of the nanotube and extend the lifetime of the photo-induced carriers. The electrode showed the best photoelectric property, and the photocurrent intensity was maximized (29.6 µA). However, the calcination process with over-temperature resulted in substantial loss of the TiO2 oxide layer, mouth clogging, and a severe decline in the photoelectric properties. PMID:27451743

  18. 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. PMID:24206769

  19. Individual Optimization of the Insertion of a Preformed Cochlear Implant Electrode Array

    PubMed Central

    Rau, Thomas S.; Lenarz, Thomas; Majdani, Omid

    2015-01-01

    Purpose. The aim of this study was to show that individual adjustment of the curling behaviour of a preformed cochlear implant (CI) electrode array to the patient-specific shape of the cochlea can improve the insertion process in terms of reduced risk of insertion trauma. Methods. Geometry and curling behaviour of preformed, commercially available electrode arrays were modelled. Additionally, the anatomy of each small, medium-sized, and large human cochlea was modelled to consider anatomical variations. Finally, using a custom-made simulation tool, three different insertion strategies (conventional Advanced Off-Stylet (AOS) insertion technique, an automated implementation of the AOS technique, and a manually optimized insertion process) were simulated and compared with respect to the risk of insertion-related trauma. The risk of trauma was evaluated using a newly developed “trauma risk” rating scale. Results. Using this simulation-based approach, it was shown that an individually optimized insertion procedure is advantageous compared with the AOS insertion technique. Conclusion. This finding leads to the conclusion that, in general, consideration of the specific curling behaviour of a CI electrode array is beneficial in terms of less traumatic insertion. Therefore, these results highlight an entirely novel aspect of clinical application of preformed perimodiolar electrode arrays in general. PMID:26448764

  20. Photoelectrocatalytic degradation of tetracycline by highly effective TiO2 nanopore arrays electrode.

    PubMed

    Liu, Yanbiao; Gan, Xiaojie; Zhou, Baoxue; Xiong, Bitao; Li, Jinhua; Dong, Chaoping; Bai, Jing; Cai, Weimin

    2009-11-15

    The widely utilization of pharmaceutical and personal care products (PPCPs) in the pharmaceutical therapies and agricultural husbandry has led to the worldwide pollution in the environment. In this study, the photoelectrocatalytic (PEC) behaviors of typical PPCPs, tetracycline (TC), were performed via a highly effective TiO(2) nanopore arrays (TNPs) electrode, comparing with electrochemical (EC) and photocatalytic (PC) process. A significant photoelectrochemical synergetic effect in TC degradation was observed on the TNPs electrode and the rate constant for the PEC process of TNPs electrode was approximately 6.7 times as high as its PC process. The TC removal rate achieved approximately 80% within 3h PEC reaction by TNPs electrode, which is approximately 25% higher than that obtained for a conventional coated TiO(2) nanofilm electrode fabricated by sol-gel method. The possible mechanism involved in the PEC degradation of TC by TNPs electrode was discussed. Furthermore, the TNPs electrode also shows enhanced photocurrent response compared with that for the coated TiO(2) nanofilm electrode. Such kind of TiO(2) nanopores will have many potential applications in various areas as an outstanding photoelectrochemical material. PMID:19577843

  1. Triggering cell detachment from patterned electrode arrays by programmed subcellular release.

    PubMed

    Wildt, Bridget; Wirtz, Denis; Searson, Peter C

    2010-07-01

    Programmed subcellular release is an in vitro technique for the quantitative study of cell detachment. The dynamics of cell contraction are measured by releasing cells from surfaces to which they are attached with spatial and temporal control. Release of subcellular regions of cells is achieved by plating cells on an electrode array created by standard microfabrication methods. The electrodes are then biochemically functionalized with an arginine-glycine-aspartic acid (RGD)-terminated thiol. Application of a voltage pulse results in electrochemical desorption of the RGD-terminated thiols, triggering cell detachment. This method allows for the study of the full cascade of events from detachment to subsequent subcellular reorganization. Fabrication of the electrode arrays may take 1-2 d. Preparation for experiments, including surface functionalization and cell plating, can be completed in 10 h. A series of cell release experiments on one device may last several hours. PMID:20595956

  2. Model-based analysis of multiple electrode array stimulation for epiretinal visual prostheses

    NASA Astrophysics Data System (ADS)

    Mueller, Jerel K.; Grill, Warren M.

    2013-06-01

    Objective. Epiretinal stimulation, which uses an array of electrodes implanted on the inner retinal surface to relay a representation of the visual scene to the neuronal elements of the retina, has seen considerable success. The objective of the present study was to quantify the effects of multi-electrode stimulation on the patterns of neural excitation in a computational model of epiretinal stimulation. Approach. A computational model of retinal ganglion cells was modified to represent the morphology of human retinal ganglion cells and validated against published experimental data. The ganglion cell model was then combined with a model of an axon of the nerve fiber layer to produce a population model of the inner retina. The response of the population of model neurons to epiretinal stimulation with a multi-electrode array was quantified across a range of electrode geometries using a novel means to quantify the model response—the minimum radius circle bounding the activated model neurons as a proxy for the evoked phosphene. Main results. Multi-electrode stimulation created unique phosphenes, such that the number of potential phosphenes can far exceed the number of electrode contacts. Significance. The ability to exploit the spatial and temporal interactions of stimulation may be critical to improvements in the performance of epiretinal prostheses.

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

    NASA Technical Reports Server (NTRS)

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

  4. Nitrogen-Doped Carbon Nanocoil Array Integrated on Carbon Nanofiber Paper for Supercapacitor Electrodes.

    PubMed

    Choi, Won Ho; Choi, Mi Jin; Bang, Jin Ho

    2015-09-01

    Integrating a nanostructured carbon array on a conductive substrate remains a challenging task that presently relies primarily on high-vacuum deposition technology. To overcome the problems associated with current vacuum techniques, we demonstrate the formation of an N-doped carbon array by pyrolysis of a polymer array that was electrochemically grown on carbon fiber paper. The resulting carbon array was investigated for use as a supercapacitor electrode. In-depth surface characterization results revealed that the microtextural properties, surface functionalities, and degree of nitrogen incorporated into the N-doped carbon array can be delicately controlled by manipulating carbonization temperatures. Furthermore, electrochemical measurements showed that subtle changes in these physical properties resulted in significant changes in the capacitive behavior of the N-doped carbon array. Pore structures and nitrogen/oxygen functional groups, which are favorable for charge storage, were formed at low carbonization temperatures. This result showed the importance of having a comprehensive understanding of how the surface characteristics of carbon affect its capacitive performance. When utilized as a substrate in a pseudocapacitive electrode material, the N-doped carbon array maximizes capacitive performance by simultaneously achieving high gravimetric and areal capacitances due to its large surface area and high electrical conductivity. PMID:26264641

  5. High Density Nano-Electrode Array for Radiation Detection

    SciTech Connect

    Mano Misra

    2010-05-07

    Bulk single crystals of Cd1-xZnxTe (x=0.04 to x=0.2) compound semiconductor is used for room temperature radiation detection. The production of large volume of Cd1-xZnxTe with low defect density is expensive. As a result there is a growing research interest in the production of nanostructured compound semiconductors such as Cd1-xZnxTe in an electrochemical route. In this investigation, Cd1-xZnxTe ternary compound semiconductor, referred as CZT, was electrodeposited in the form of nanowires onto a TiO2 nanotubular template from propylene carbonate as the non-aqueous electrolyte, using a pulse-reverse electrodeposition process at 130 ºC. The template acted as a support in growing ordered nanowire of CZT which acts as a one dimensional conductor. Cyclic Voltammogram (CV) studies were conducted in determining the potentials for the growth of nanowires of uniform stoichiometry. The morphologies and composition of CZT were characterized by using SEM, TEM and XRD. The STEM mapping carried out on the nanowires showed the uniform distribution of Cd, Zn and Te elements. TEM image showed that the nanowires were polycrystalline in nature. The Mott-Schottky analysis carried on the nanowires showed that the nanowires were a p-type semiconductor. The carrier density, band gap and resistivity of the Cd0.9Zn0.1Te nanowires were 4.29x1013 cm-3, 1.56 eV and 2.76x1011Ω-cm respectively. The high resistivity was attributed to the presence of deep defect states such as cadmium vacancies or Te antisites which were created by the anodic cycle of the pulse-reverse electrodeposition process. Stacks of series connected CZT nanowire arrays were tested with different bias potentials. The background current was in the order of tens of picoamperes. When exposed to radiation source Amerecium-241 (60 KeV, 4 μCi), the stacked CZT nanowires arrays showed sensing behavior. The sensitivity of the nanowire arrays increased as the number of stacks increased. The preliminary results indicate that the

  6. Biochips Containing Arrays of Carbon-Nanotube Electrodes

    NASA Technical Reports Server (NTRS)

    Li, Jun; Meyyappan, M.; Koehne, Jessica; Cassell, Alan; Chen, Hua

    2008-01-01

    Biochips containing arrays of nanoelectrodes based on multiwalled carbon nanotubes (MWCNTs) are being developed as means of ultrasensitive electrochemical detection of specific deoxyribonucleic acid (DNA) and messenger ribonucleic acid (mRNA) biomarkers for purposes of medical diagnosis and bioenvironmental monitoring. In mass production, these biochips could be relatively inexpensive (hence, disposable). These biochips would be integrated with computer-controlled microfluidic and microelectronic devices in automated hand-held and bench-top instruments that could be used to perform rapid in vitro genetic analyses with simplified preparation of samples. Carbon nanotubes are attractive for use as nanoelectrodes for detection of biomolecules because of their nanoscale dimensions and their chemical properties.

  7. Intracellular Protein Delivery and Gene Transfection by Electroporation Using a Microneedle Electrode Array

    PubMed Central

    Choi, Seong-O; Kim, Yeu-Chun; Lee, Jeong Woo; Park, Jung-Hwan

    2012-01-01

    The impact of many biopharmaceuticals, including protein- and gene-based therapies, has been limited by the need for better methods of delivery into cells within tissues. Here, we present intracellular delivery of molecules and transfection with plasmid DNA by electroporation using a novel microneedle electrode array designed for targeted treatment of skin and other tissue surfaces. The microneedle array is molded out of polylactic acid. Electrodes and circuitry required for electroporation are applied to the microneedle array surface by a new metal-transfer micromolding method. The microneedle array maintains mechanical integrity after insertion into pig cadaver skin and is able to electroporate human prostate cancer cells in vitro. Quantitative measurements show that increasing electroporation pulse voltage increases uptake efficiency of calcein and bovine serum albumin, whereas increasing pulse length has lesser effects over the range studied. Uptake of molecules by up to 50 % of cells and transfection of 12 % of cells with a gene for green fluorescent protein is demonstrated at high cell viability. We conclude that the microneedle electrode array is able to electroporate cells, resulting in intracellular uptake of molecules, and has potential applications to improve intracellular delivery of proteins, DNA and other biopharmaceuticals. PMID:22328093

  8. Step-by-step instructions for retina recordings with perforated multi electrode arrays.

    PubMed

    Reinhard, Katja; Tikidji-Hamburyan, Alexandra; Seitter, Hartwig; 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

  9. 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

  10. Preparation of nickel nanowire arrays electrode for urea electro-oxidation in alkaline medium

    NASA Astrophysics Data System (ADS)

    Guo, Fen; Ye, Ke; Cheng, Kui; Wang, Guiling; Cao, Dianxue

    2015-03-01

    Fully metallic nickel nanowire arrays (NWAs) electrode is prepared by electrodepositing nickel within the pores and over-plating on the surface of polycarbonate template (PCT) with subsequent dissolution of the template in dichloromethane. The as-prepared electrode is characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Urea electro-oxidation reaction in KOH solution on the nickel NWAs electrode is investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The results show that the nickel NWAs electrode achieves an onset oxidation potential of 0.25 V (vs. Ag/AgCl) and a peak current density of 160 mA cm-2 in 5 mol L-1 KOH and 0.33 mol L-1 urea accompanied with considerable stability.

  11. Development of Individually Addressable Micro-Mirror-Arrays for Space Applications

    NASA Technical Reports Server (NTRS)

    Dutta, Sanghamitra B.; Ewin, Audrey J.; Jhabvala, Murzy; Kotecki, Carl A.; Kuhn, Jonathan L.; Mott, D. Brent

    2000-01-01

    We have been developing a 32 x 32 prototype array of individually addressable Micro-Mirrors capable of operating at cryogenic temperature for Earth and Space Science applications. Micro-Mirror-Array technology has the potential to revolutionize imaging and spectroscopy systems for NASA's missions of the 21st century. They can be used as programmable slits for the Next Generation Space Telescope, as smart sensors for a steerable spectrometer, as neutral density filters for bright scene attenuation etc. The, entire fabrication process is carried out in the Detector Development Laboratory at NASA, GSFC. The fabrication process is low temperature compatible and involves integration of conventional CMOS technology and surface micro-machining used in MEMS. Aluminum is used as the mirror material and is built on a silicon substrate containing the CMOS address circuit. The mirrors are 100 microns x l00 microns in area and deflect by +/- 10 deg induced by electrostatic actuation between two parallel plate capacitors. A pair of thin aluminum torsion straps allow the mirrors to tilt. Finite-element-analysis and closed form solutions using electrostatic and mechanical torque for mirror operation were developed and the results were compared with laboratory performance. The results agree well both at room temperature and at cryogenic temperature. The development demonstrates the first cryogenic operation of two-dimensional Micro-Mirrors with bi-state operation. Larger arrays will be developed meeting requirements for different science applications. Theoretical analysis, fabrication process, laboratory test results and different science applications will be described in detail.

  12. High frequency glow discharges at atmospheric pressure with micro-structured electrode arrays

    NASA Astrophysics Data System (ADS)

    Baars-Hibbe, L.; Sichler, P.; Schrader, C.; Lucas, N.; Gericke, K.-H.; Büttgenbach, S.

    2005-02-01

    Micro-structured electrode (MSE) arrays allow the generation of large-area uniform glow discharges over a wide pressure range up to atmospheric pressure. The electrode widths, thicknesses and distances in the micrometre range are realized by means of modern micro-machining and galvanic techniques. The electrode distance, the gap width d, is small enough to generate sufficiently high electric field strengths to ignite gas discharges by applying only moderate radio frequency (RF, 13.56 MHz) voltages (80-390 V in Ne, He, Ar, N2 and air). The non-thermal plasma system is characterized by a special probe measuring the electric parameters. We tested MSE arrays with d = 70, 25 and 15 µm. The MSE driven plasmas show a different behaviour from conventional RF discharge plasmas. Due to the very small electrode gap width we can describe the behaviour of the charged particles in the RF field of our system with the dc Townsend breakdown theory, depending on the pressure range and gas. With decreasing pressure, the gas discharges, especially in Ne and He, are increasingly dominated by field electron emission. With the MSE arrays as plasma sources several applications were developed and successfully tested, e.g. decomposition of waste gases and sterilization of food packaging materials at atmospheric pressure.

  13. Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications

    PubMed Central

    Park, Dong-Wook; Schendel, Amelia A.; Mikael, Solomon; Brodnick, Sarah K.; Richner, Thomas J.; Ness, Jared P.; Hayat, Mohammed R.; Atry, Farid; Frye, Seth T.; Pashaie, Ramin; Thongpang, Sanitta; Ma, Zhenqiang; Williams, Justin C.

    2014-01-01

    Neural micro-electrode arrays that are transparent over a broad wavelength spectrum from ultraviolet to infrared could allow for simultaneous electrophysiology and optical imaging, as well as optogenetic modulation of the underlying brain tissue. The long-term biocompatibility and reliability of neural micro-electrodes also require their mechanical flexibility and compliance with soft tissues. Here we present a graphene-based, carbon-layered electrode array (CLEAR) device, which can be implanted on the brain surface in rodents for high-resolution neurophysiological recording. We characterize optical transparency of the device at >90% transmission over the ultraviolet to infrared spectrum and demonstrate its utility through optical interface experiments that use this broad spectrum transparency. These include optogenetic activation of focal cortical areas directly beneath electrodes, in vivo imaging of the cortical vasculature via fluorescence microscopy and 3D optical coherence tomography. This study demonstrates an array of interfacing abilities of the CLEAR device and its utility for neural applications. PMID:25327513

  14. Design of Circle Array Pattern for Transparent Nanomesh-Type Electrodes.

    PubMed

    Shin, Seungsu; Ganorkar, Shraddha; Kim, Jungyoon; Kim, Young-Hwan; Kim, Yong Tae; Kim, Seong-Il

    2015-10-01

    In this study, we report simulation results for the optical properties of nanomesh-type electrodes for transparent electrode. Usually, indium tin oxide (ITO) is commonly used for transparent conductor to solar cell, display, LED and other electronic modules. However, the cost is high due to the rarity of indium. An alternative way is use of transparent nanomesh-type metal electrode for solar cell. Finite different time domain (FDTD) method was used to simulate and analyze their optical properties. Various array patterns (square, circle and circle hexagonal array) of metal on glass (SiO2) substrates were designed and their properties of transmission and reflection were simulated by using the broad band (λ = 300~1200 nm) plane wave source. To compare basic characteristics of each pattern, various structural parameters such as hole diameter, pitch and metal thickness were applied. The effect of three typical metals, such as Ag, Au, and Al was also compared. In the results, we will discuss about large dip of transmission appeared at the particular wavelength region from the circle array pattern, which is design with pitch of 500 nm at the wavelength range 700 to 800 nm. The surface plasmonpolaritons (SPP) effect can be the cause of large dip and we could find a broad and high transmission from the properly designed in nanomesh-type electrodes, which was calculated as a function of wavelength. PMID:26726388

  15. Interdigitated electrode array based sensors for environmental monitoring of caesium

    NASA Astrophysics Data System (ADS)

    Nickson, I. D.; Boxall, C.; Port, S. N.

    2010-03-01

    The requirement for on-line and in-situ monitoring of analytes in process and effluent streams and in ground waters has become increasingly more important in recent years. We therefore describe the development of the transduction element for a fully automated online instrument for the detection of caesium. The sensor layer for this instrument employs an Ion Selective Conductimetric Microsensor (ISCOM) as the detector. This is based upon a plasticized polymeric membrane incorporating a selective ionophore, overlaying two interdigitated microelectrode arrays. A direct relationship has been observed between the bulk conductance (as determined by the microelectrodes) of the ionophore loaded membrane and the concentration of the primary ions in solution. Caesium selective ISCOMs were prepared using an ion selective membrane containing the commercially available ionophore Calix [6]arene-hexaacetic acid hexaethyl ester, polyvinylchloride (PVC) and plasticiser Nitrophenylether (NPOE). The relative levels of membrane components have also been varied in order to further enhance the ISCOM response. We also present preliminary data concerning the caesium selectivity with respect to a range of possible interferents, including rubidium.

  16. Adult Cortical Plasticity Studied with Chronically Implanted Electrode Arrays

    PubMed Central

    Abe, Hiroshi; McManus, Justin N.J.; Ramalingam, Nirmala; Li, Wu; Marik, Sally A.; Meyer zum Alten Borgloh, Stephan

    2015-01-01

    The functional architecture of adult cerebral cortex retains a capacity for experience-dependent change. This is seen after focal binocular lesions as rapid changes in receptive field (RF) of the lesion projection zone (LPZ) in the primary visual cortex (V1). To study the dynamics of the circuitry underlying these changes longitudinally, we implanted microelectrode arrays in macaque (Macaca mulatta) V1, eliminating the possibility of sampling bias, which was a concern in previous studies. With this method, we observed a rapid initial recovery in the LPZ and, during the following weeks, 63–89% of the sites in the LPZ showed recovery of visual responses with significant position tuning. The RFs shifted ∼3° away from the scotoma. In the absence of a lesion, visual stimulation surrounding an artificial scotoma did not elicit visual responses, suggesting that the postlesion RF shifts resulted from cortical reorganization. Interestingly, although both spikes and LFPs gave consistent prelesion position tuning, only spikes reflected the postlesion remapping. PMID:25673865

  17. Analysis of traveling-wave electro-osmotic pumping with double-sided electrode arrays

    NASA Astrophysics Data System (ADS)

    Yeh, Hung-Chun; Yang, Ruey-Jen; Luo, Win-Jet

    2011-05-01

    In this paper, a series of numerical simulations was performed to investigate the pumping performance of electro-osmotic micropumps containing electrode arrays patterned on the upper and lower sides of a microchannel. The simulations have been analyzed with a linear electro-osmotic model based upon the Debye-Hückel theory of the double layer. The potential drop across the diffuse layer is assumed to be less than 25 mV (kBT/e), and there is a linear response between the surface charge and the voltage drop across the double layer. The double layer is not resolved but is lumped into effective parameters that are imported from the Debye-Hückel and Stern layers. We examined the effects of the relative positioning of the electrodes in the opposing arrays (i.e., symmetrical or staggered), and the phase lag and the angular frequency of the alternating current (ac) signals applied to the electrodes within the two arrays. A critical height of the microchannel was observed, below which the interactions of the applied electrical potentials on the walls became significant. The optimum pumping effect was obtained when the electrode arrays were symmetrical to one another around the centerline of the channel and were activated by ac potentials with a 0° phase shift. The corresponding angular frequency of the maximum pumping velocity for different phase shifts of the applied ac signals was also determined. Overall, the simulation results presented in this paper provide a useful insight into the optimal design parameters and operating conditions for micropumps containing two arrays of microelectrodes on the microchannel walls.

  18. Integration of diffractive lenses with addressable vertical-cavity laser arrays

    SciTech Connect

    Warren, M.E.; Du, T.C.; Wendt, J.R.; Vawter, G.A.; Carson, R.F.; Lear, K.L.; Kilcoyne, S.P.; Schneider, R.P.; Zolper, J.C.

    1995-04-01

    An optical interconnection system is being developed to provide vertical, digital data channels for stacked multichip modules. A key component of the system is an array of individually addressable vertical-cavity surface-emitting lasers with diffractive lenses integrated into the substrate to control beam divergence and direction. The lenses were fabricated by direct-write e-beam lithography and reactive ion beam etching into the GaAs substrate. Preliminary device performance data and the design and fabrication issues are discussed.

  19. Fabrication of a carbon nanotube protruding electrode array for a retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Wang, Ke; Dai, Hongjie; Fishman, Harvey A.; Harris, James S.

    2005-01-01

    Implantable retinal prosthetic devices consisting of microelectrode arrays are being built in attempts to restore vision. Current retinal prostheses use metal planar electrodes. We are developing a novel electro-neural interface using carbon nanotube (CNT) bundles as flexible, protruding microelectrodes. We have synthesized vertically self-assembled, multi-walled CNT bundles by thermal chemical vapor deposition. Using conventional silicon-based micro-fabrication processes, these CNT bundles were integrated onto pre-patterned circuits. CNT protruding electrodes have significant potentials in providing safer stimulation for retinal prostheses. They could also act as recording units to sense electrical and chemical activities in neural systems for fundamental neuroscience research.

  20. Optimization of discharge types and electrode structure in a cylinder discharge reactor with saw-wheel array electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Chunyang; Shang, Kefeng; Lu, Na; Li, Jie; Wu, Yan

    2013-03-01

    The application of corona discharge technology in gas purification and wastewater treatment has been received great attention in recent years. The configuration of discharge electrode and the discharge types directly affect the discharge power and the power density, and then affect the generation of active species as well as the removal efficiency of pollutants. A novel cylinder-type discharge reactor with saw-wheel-array electrodes was developed for removal of SO2/NOx from flue gas, and influence factors such as electrode structure (ratio of spacing of saw-wheel slices and discharge distance, herein defined as R) and power supply types (positive DC, negative DC, and pulse power) on discharge characteristics and the output power was discussed. The experimental results show that the current and output power of three types of discharges firstly increased with R increasing from 0.3-1.7, and then tended to a stability from 1.7-2.5 while the power density reached a maximum at the ratio of 1.7.

  1. Nano electrode arrays for in-situ identification and quantification of chemicals in water.

    SciTech Connect

    Gurule, Natalia J.; Kelly, Michael James; Brevnov, Dmitri A.; Ashby, Carol Iris Hill; Pfeifer, Kent Bryant; Yelton, William Graham

    2004-12-01

    The nano electrode arrays for in-situ identification and quantification of chemicals in water progress in four major directions. (1) We developed and engineering three nanoelectrode array designs which operate in a portable field mode or as distributed sensor network for water systems. (2) To replace the fragile glass electrochemical cells using in the lab, we design and engineered field-ready sampling heads that combine the nanoelectrode arrays with a high-speed potentiostat. (3) To utilize these arrays in a portable system we design and engineered a light weight high-speed potentiostat with pulse widths from 2 psec. to 100 msec. or greater. (4) Finally, we developed the parameters for an analytical method in low-conductivity solutions for Pb(II) detection, with initial studies for the analysis of As(III) and As(V) analysis in natural water sources.

  2. A Cosmic Dust Sensor Based on an Array of Grid Electrodes

    NASA Astrophysics Data System (ADS)

    Li, Y. W.; Bugiel, S.; Strack, H.; Srama, R.

    2014-04-01

    We described a low mass and high sensitivity cosmic dust trajectory sensor using a array of grid segments[1]. the sensor determines the particle velocity vector and the particle mass. An impact target is used for the detection of the impact plasma of high speed particles like interplanetary dust grains or high speed ejecta. Slower particles are measured by three planes of grid electrodes using charge induction. In contrast to conventional Dust Trajectory Sensor based on wire electrodes, grid electrodes a robust and sensitive design with a trajectory resolution of a few degree. Coulomb simulation and laboratory tests were performed in order to verify the instrument design. The signal shapes are used to derive the particle plane intersection points and to derive the exact particle trajectory. The accuracy of the instrument for the incident angle depends on the particle charge, the position of the intersection point and the signal-to-noise of the charge sensitive amplifier (CSA). There are some advantages of this grid-electrodes based design with respect to conventional trajectory sensor using individual wire electrodes: the grid segment electrodes show higher amplitudes (close to 100%induced charge) and the overall number of measurement channels can be reduced. This allows a compact instrument with low power and mass requirements.

  3. A comparison of headnet electrode arrays for electrical impedance tomography of the human head.

    PubMed

    Tidswell, A T; Bagshaw, A P; Holder, D S; Yerworth, R J; Eadie, L; Murray, S; Morgan, L; Bayford, R H

    2003-05-01

    Three types of commercially available headnet electrode arrays, designed for use in EEG, and conventional EEG Ag/AgCl cup electrodes were tested on human subjects, and a realistic, saline-filled head-shaped tank was prepared with vegetable skin to simulate human skin in order to determine the optimum electrode system for electrical impedance tomography (EIT) of the human head. Impedance changes during EIT acquisition were produced in healthy volunteers during a finger-thumb apposition task and in tanks by the insertion of a Perspex rod. Signal-to-baseline noise, measured from raw EIT data, was 2.3 +/- 0.3 and 2.3 +/- 0.2 for the human and tank data, respectively. In both the human and tank experiments, a commercial hydrogel elasticated electrode headnet produced the least amount of baseline noise, and was the only headnet in the human data with noise levels acceptable for EIT imaging. Image quality measured in the tank was similar for most of the headnets tested, except that the EEG electrodes produced a higher positional error and electrodes in a geodesic elasticated net produced images with worse subjective image quality. Overall, the hydrogel elasticated headnet was judged to be the most suitable for human neuroimaging with EIT. PMID:12812436

  4. Time of Flight Electrochemistry: Diffusion Coefficient Measurements Using Interdigitated Array (IDA) Electrodes

    SciTech Connect

    Liu, Fei; Kolesov, Grigory; Parkinson, Bruce A.

    2014-09-26

    A simple and straightforward method for measuring diffusion coefficients using interdigitated array (IDA) electrodes is reported. The method does not require that the exact electrode area be known but depends only the size of the gap between the IDA electrode pairs. Electroactive molecules produced at the generator electrode of the IDA by a voltage step or scan can diffuse to the collector electrode and the time delay before the current for the reverse electrochemical reaction is detected at the collector is used to calculate the diffusion coefficient. The measurement of the diffusion rate of Ru(NH3)6+2 in aqueous solution has been used as an example measuring diffusion coefficients using this method. Additionally, a digital simulation of the electrochemical response of the IDA electrodes was used to simulate the entire current/voltage/time behavior of the system and verify the experimentally measured diffusion coefficients. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science, Office of Basic Energy Sciences.

  5. Vertically integrated sensor array technology for unattended sensor networks (Keynote Address)

    NASA Astrophysics Data System (ADS)

    Balcerak, Raymond; Thurston, John; Breedlove, Jonathan

    2005-05-01

    The increasing need for unattended sensor networks drives individual sensor development, signal processing for network management, and communication technology. The application space is becoming more complex, with requirements for sensor networks in force protection; surveillance of large expanses of rugged terrain; and monitoring complex urban areas. Individual sensors exhibit excellent performance and include a wide variety of sensing modes, such as acoustic, electro-optical imaging, seismic, and radio frequency devices. These sensors continue to shrink with packaging, while applications continue to demand more of the sensor technology. Although single imaging arrays, which are available in spectral bands from the visible through the infrared, can be integrated into packages size as small as a cubic inch, the information from a single sensor is not sufficient to meet requirements for day/night, all-weather operation. This has driven the need for integration of multiple sensors into the compact packages intended for an individual sensor. A major step toward addressing the need for more effective sensor technology for unattended sensor networks is being taken through development of Vertically Integrated Sensor Array (VISA) technology. This technology, currently being developed for imaging sensors, builds multiple layers of signal processing at each pixel in the sensor array. Processing power is dramatically increased, allowing the integration of multiple sensors in small compact packages. This paper reviews the VISA approach to imaging sensors and describes applications for unattended sensors.

  6. A Spherical Electrode Array for the Detection of Stretched Induced Arrhythmias

    NASA Astrophysics Data System (ADS)

    Kieron, M. E.; Parker, K. P.; Wikswo, J. W.

    1997-11-01

    A heart tank containing electrodes positioned at the vertices of a icosahedron was built to measure the epicardial potentials from a perfused rabbit heart. From the isopotential maps, the electrical source can be deduced. In addition, an inverse calculation can be performed to determine the multipole components and, thus, the dipole origin via a least squares method. It is hypothesized that stretched induced foci are located in the Purkinje conductive system. To find these foci, we are developing a LabVIEW based data acquisition system and a spherical heart tank consisting of 126 electrodes to record the potentials around a rabbit heart. The unipolar electrodes are fabricated from 26 AWG Cu magnet wire on which Ag was plated then chlorided to produce nonpolarizable electrodes required for the low level signals. The signals are amplified and filtered prior to A/D conversion and subsequent source analysis with MATLAB. Biocompatibility, EM interference, grounding, and other design considerations will be addressed.

  7. Neural recording stability of chronic electrode arrays in freely behaving primates.

    PubMed

    Linderman, Michael D; Gilja, Vikash; Santhanam, Gopal; Afshar, Afsheen; Ryu, Stephen; Meng, Teresa H; Shenoy, Krishna V

    2006-01-01

    Chronically implanted electrode arrays have enabled a broad range of advances, particularly in the field of neural prosthetics. Those successes motivate development of prototype implantable prosthetic processors for long duration, continuous use in freely behaving subjects. However, traditional experimental protocols have provided limited information regarding the stability of the electrode arrays and their neural recordings. In this paper we present preliminary results derived from long duration neural recordings in a freely behaving primate which show variations in action potential shape and RMS noise across a range of time scales. These preliminary results suggest that spike sorting algorithms can no longer assume stable neural signals and will need to transition to adaptive signal processing methodologies to maximize performance. PMID:17946626

  8. 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

  9. Theoretical Optimization of Stimulation Strategies for a Directionally Segmented Deep Brain Stimulation Electrode Array.

    PubMed

    Xiao, YiZi; Peña, Edgar; Johnson, Matthew D

    2016-02-01

    Programming deep brain stimulation (DBS) systems currently involves a clinician manually sweeping through a range of stimulus parameter settings to identify the setting that delivers the most robust therapy for a patient. With the advent of DBS arrays with a higher number and density of electrodes, this trial and error process becomes unmanageable in a clinical setting. This study developed a computationally efficient, model-based algorithm to estimate an electrode configuration that will most strongly activate tissue within a volume of interest. The cerebellar-receiving area of motor thalamus, the target for treating essential tremor with DBS, was rendered from imaging data and discretized into grid points aligned in approximate afferent and efferent axonal pathway orientations. A finite-element model (FEM) was constructed to simulate the volumetric tissue voltage during DBS. We leveraged the principle of voltage superposition to formulate a convex optimization-based approach to maximize activating function (AF) values at each grid point (via three different criteria), hence increasing the overall probability of action potential initiation and neuronal entrainment within the target volume. For both efferent and afferent pathways, this approach achieved global optima within several seconds. The optimal electrode configuration and resulting AF values differed across each optimization criteria and between axonal orientations. This approach only required a set of FEM simulations equal to the number of DBS array electrodes, and could readily accommodate anisotropic-inhomogeneous tissue conductances or other axonal orientations. The algorithm provides an efficient, flexible determination of optimal electrode configurations for programming DBS arrays. PMID:26208259

  10. Efficient piezoelectric ZnO nanogenerators based on Au-coated silica sphere array electrode

    PubMed Central

    2013-01-01

    We reported ZnO nanorod-based piezoelectric nanogenerators (NGs) with Au-coated silica sphere array as an efficient top electrode. This electrode can readily bend the ZnO nanorods due to its enhanced surface roughness, thus resulting in more increased and regular piezoelectric charge output. Under a low external pushing force of 0.3 kgf, the output current and voltage were increased by approximately 2.01 and 1.51 times, respectively, in comparison with a conventional Au top electrode without silica spheres. Also, the effect of Au-coated silica spheres on the bending radius of ZnO nanorods was theoretically investigated. PMID:24305510

  11. Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring

    PubMed Central

    Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

    2016-01-01

    A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring. PMID:27322278

  12. Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring.

    PubMed

    Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

    2016-01-01

    A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring. PMID:27322278

  13. In vivo neuronal action potential recordings via three-dimensional microscale needle-electrode arrays

    PubMed Central

    Fujishiro, Akifumi; Kaneko, Hidekazu; Kawashima, Takahiro; Ishida, Makoto; Kawano, Takeshi

    2014-01-01

    Very fine needle-electrode arrays potentially offer both low invasiveness and high spatial resolution of electrophysiological neuronal recordings in vivo. Herein we report the penetrating and recording capabilities of silicon-growth-based three-dimensional microscale-diameter needle-electrodes arrays. The fabricated needles exhibit a circular-cone shape with a 3-μm-diameter tip and a 210-μm length. Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters. Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz–10 kHz. The needles can penetrate into the whisker barrel area of a rat's cerebral cortex, and the action potentials recorded from some neurons exhibit peak-to-peak amplitudes of ~300 μVpp. These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology. PMID:24785307

  14. In vivo neuronal action potential recordings via three-dimensional microscale needle-electrode arrays

    NASA Astrophysics Data System (ADS)

    Fujishiro, Akifumi; Kaneko, Hidekazu; Kawashima, Takahiro; Ishida, Makoto; Kawano, Takeshi

    2014-05-01

    Very fine needle-electrode arrays potentially offer both low invasiveness and high spatial resolution of electrophysiological neuronal recordings in vivo. Herein we report the penetrating and recording capabilities of silicon-growth-based three-dimensional microscale-diameter needle-electrodes arrays. The fabricated needles exhibit a circular-cone shape with a 3-μm-diameter tip and a 210-μm length. Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters. Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz-10 kHz. The needles can penetrate into the whisker barrel area of a rat's cerebral cortex, and the action potentials recorded from some neurons exhibit peak-to-peak amplitudes of ~300 μVpp. These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology.

  15. In vivo neuronal action potential recordings via three-dimensional microscale needle-electrode arrays.

    PubMed

    Fujishiro, Akifumi; Kaneko, Hidekazu; Kawashima, Takahiro; Ishida, Makoto; Kawano, Takeshi

    2014-01-01

    Very fine needle-electrode arrays potentially offer both low invasiveness and high spatial resolution of electrophysiological neuronal recordings in vivo. Herein we report the penetrating and recording capabilities of silicon-growth-based three-dimensional microscale-diameter needle-electrodes arrays. The fabricated needles exhibit a circular-cone shape with a 3-μm-diameter tip and a 210-μm length. Due to the microscale diameter, our silicon needles are more flexible than other microfabricated silicon needles with larger diameters. Coating the microscale-needle-tip with platinum black results in an impedance of ~600 kΩ in saline with output/input signal amplitude ratios of more than 90% at 40 Hz-10 kHz. The needles can penetrate into the whisker barrel area of a rat's cerebral cortex, and the action potentials recorded from some neurons exhibit peak-to-peak amplitudes of ~300 μVpp. These results demonstrate the feasibility of in vivo neuronal action potential recordings with a microscale needle-electrode array fabricated using silicon growth technology. PMID:24785307

  16. Three-dimensional nanotube electrode arrays for hierarchical tubular structured high-performance pseudocapacitors.

    PubMed

    Gao, Yuan; Lin, Yuanjing; Chen, Jiaqi; Lin, Qingfeng; Wu, Yue; Su, Wenjun; Wang, Wenli; Fan, Zhiyong

    2016-07-21

    Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with high uniformity. The large surface area of such a structure leads to remarkable surface area enhancement up to 51.8 times compared to a planar structure. Combining with electrochemically deposited manganese dioxide (MnO2) nanoflakes on the inner side wall of the FTO nanotubes, the unique hierarchical tubular structured pseudocapacitor electrode demonstrated the highest areal capacitance of 193.8 mF cm(-2) at the scan rate of 5 mV s(-1) and 184 mF cm(-2) at the discharge current density of 0.6 mA cm(-2), which is 18.5 times that of a planar electrode. And it also showed a volumetric capacitance of 112.6 F cm(-3) at the scan rate of 5 mV s(-1) and 108.8 F cm(-3) at the discharge current density of 0.6 mA cm(-2). In addition, the cyclic stability test also indicated that a nanostructured pseudocapacitive electrode has a much larger capacitance retention after 3000 cycles of the charge-discharge process compared with a planar electrode, primarily due to the mechanical stability of the nanostructure. Moreover, pseudocapacitor device fabrication based on such electrodes shows the volumetric capacitance of 17.5 F cm(-3), and the highest specific energy of 1.56 × 10(-3) Wh cm(-3). With the merit of facile fabrication procedures and largely enhanced electrochemical performance, such a 3-D structure has high potency for energy storage systems for a wide range of practical applications. PMID:27337295

  17. Single-crystalline Ni(OH)2 and NiO nanoplatelet arrays as supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Li, Jiangtian; Zhao, Wei; Huang, Fuqiang; Manivannan, Ayyakkannu; Wu, Nianqiang

    2011-12-01

    Vertically aligned Ni(OH)2 and NiO single-crystalline nanoplatelet arrays were directly grown on the fluorine-doped tin oxide (FTO) substrate by a simple hydrothermal method. The effects of the hydrothermal parameters on the morphology and crystal structure of the nanoarray film were investigated. Controlling the ammonia and persulfate concentrations was the key to controlling the morphology of the nanoarray film. The experimental results showed that the single-crystalline NiO nanoplatelet array was a promising candidate for the supercapacitor electrode. It exhibited a high specific capacitance, prompt charge/discharge rate, and good stability of cycling performance. It is believed that the vertically oriented aligned single-crystalline NiO nanoplatelet array is beneficial to the charge transfer in the electrode and to the ion transport in the solution during redox reaction.Vertically aligned Ni(OH)2 and NiO single-crystalline nanoplatelet arrays were directly grown on the fluorine-doped tin oxide (FTO) substrate by a simple hydrothermal method. The effects of the hydrothermal parameters on the morphology and crystal structure of the nanoarray film were investigated. Controlling the ammonia and persulfate concentrations was the key to controlling the morphology of the nanoarray film. The experimental results showed that the single-crystalline NiO nanoplatelet array was a promising candidate for the supercapacitor electrode. It exhibited a high specific capacitance, prompt charge/discharge rate, and good stability of cycling performance. It is believed that the vertically oriented aligned single-crystalline NiO nanoplatelet array is beneficial to the charge transfer in the electrode and to the ion transport in the solution during redox reaction. Electronic supplementary information (ESI) available: XRD patterns of Ni(OH)2 and NiO powders; SEM and TEM images of Ni(OH)2 and NiO nanoplatelet arrays; and electrochemical performances for NiO nanoarrays and powders. See

  18. Stripe- or square-patterned arrays of tin dioxide nanowires for use in lithium-ion battery electrodes

    NASA Astrophysics Data System (ADS)

    Lee, Sang Ho; Kim, Won Bae

    2016-03-01

    This paper reports a novel electrode design for use in electrochemical lithium-ion storage. 3-dimensional patterns of tin dioxide nanowires that are grown directly over current collectors are suggested as electrode frameworks, representing the synergetic combination of nanometer-sized 1-dimensional electrode materials and micrometer-scaled hollow channels formed between the patterned nanowire arrays. The lithium-ion storage properties are investigated by changing the pattern geometries of these nanowire arrays in the shape of stripes and squares. The proposed electrode platforms show the enhanced electrochemical storage performances, which might be attributed to the effective diffusion of liquid phase electrolyte through the hollow channels between these patterned nanowire arrays. More interestingly, with increasing the hollow channels in these proposed systems, the high-rate performance and cycling stability are improved even further due to the structural effect of these electrode frameworks.

  19. 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

    2015-12-01

    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. PMID:26575957

  20. Concurrent recordings of bladder afferents from multiple nerves using a microfabricated PDMS microchannel electrode array.

    PubMed

    Delivopoulos, Evangelos; Chew, Daniel J; Minev, Ivan R; Fawcett, James W; Lacour, Stéphanie P

    2012-07-21

    In this paper we present a compliant neural interface designed to record bladder afferent activity. We developed the implant's microfabrication process using multiple layers of silicone rubber and thin metal so that a gold microelectrode array is embedded within four parallel polydimethylsiloxane (PDMS) microchannels (5 mm long, 100 μm wide, 100 μm deep). Electrode impedance at 1 kHz was optimized using a reactive ion etching (RIE) step, which increased the porosity of the electrode surface. The electrodes did not deteriorate after a 3 month immersion in phosphate buffered saline (PBS) at 37 °C. Due to the unique microscopic topography of the metal film on PDMS, the electrodes are extremely compliant and can withstand handling during implantation (twisting and bending) without electrical failure. The device was transplanted acutely to anaesthetized rats, and strands of the dorsal branch of roots L6 and S1 were surgically teased and inserted in three microchannels under saline immersion to allow for simultaneous in vivo recordings in an acute setting. We utilized a tripole electrode configuration to maintain background noise low and improve the signal to noise ratio. The device could distinguish two types of afferent nerve activity related to increasing bladder filling and contraction. To our knowledge, this is the first report of multichannel recordings of bladder afferent activity. PMID:22569953

  1. A liquid crystal microlens array with aluminum and graphene electrodes for plenoptic imaging

    NASA Astrophysics Data System (ADS)

    Lei, Yu; Tong, Qing; Luo, Jun; Zhang, Xinyu; Sang, Hongshi; Xie, Changsheng

    2015-12-01

    Currently, several semiconducting oxide materials such as typical indium tin oxide are widely used as the transparent conducting electrodes (TCEs) in liquid crystal microlens arrays. In this paper, we fabricate a liquid crystal microlens array using graphene rather than semiconducting oxides as the TCE. Common optical experiments are carried out to acquire the focusing features of the graphene-based liquid crystal microlens array (GLCMLA) driven electrically. The acquired optical fields show that the GLCMLA can converge incident collimating lights efficiently. The relationship between the focal length and the applied voltage signal is presented. Then the GLCMLA is deployed in a plenoptic camera prototype and the raw images are acquired so as to verify their imaging capability. Our experiments demonstrate that graphene has already presented a broad application prospect in the area of adaptive optics.

  2. A parylene-silicon cochlear electrode array with integrated position sensors.

    PubMed

    Wang, Jianbai; Gulari, Mayurachat N; Wise, Kensall D

    2006-01-01

    A thin-film cochlear electrode array has been developed for a cochlear prosthesis to achieve improved sound perception and position accuracy. The array is fabricated using a bulk-silicon micromachining process that allows parylene deposition and patterning at wafer level, followed by a wet silicon release etch that is compatible with the use of boron etch-stops. The process is capable of realizing arrays with substrates stressed to hug the modiolar wall in the rest state and whose stiffness can be adjusted over a wide range. Built-in tip and curvature sensors respond to tip contact and bending-induced shank stress, respectively during in-vitro and in-vivo implants. The process is also compatible with the integration of parylene ribbon cables for lead transfer to an implanted electronics package. PMID:17946554

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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.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. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08370b

  4. Evaluation of Platinum-Black Stimulus Electrode Array for Electrical Stimulation of Retinal Cells in Retinal Prosthesis System

    NASA Astrophysics Data System (ADS)

    Watanabe, Taiichiro; Kobayashi, Risato; Komiya, Ken; Fukushima, Takafumi; Tomita, Hiroshi; Sugano, Eriko; Kurino, Hiroyuki; Tanaka, Tetsu; Tamai, Makoto; Koyanagi, Mitsumasa

    2007-04-01

    A retinal prosthesis system with a three-dimensionally (3D) stacked LSI chip has been proposed. We fabricated a new implantable stimulus electrode array deposited with Platinum-black (Pt-b) on a polyimide-based flexible printed circuit (FPC) for the electrical stimulation of the retinal cells. Impedance measurement of the Pt-b electrode-electrolyte interface in a saline solution was performed and the Pt-b electrode realized a very low impedance. The power consumption at the electrode array when retinal cells were stimulated by a stimulus current was evaluated. The power consumption of the Pt-b stimulus electrode array was 91% lower than that of a previously fabricated Al stimulus electrode array due to a convexo-concave surface. In the cytotoxicity test (CT), we confirmed that Pt implantation induced no cellular degeneration of the rat retina. In the animal experiments, electrically evoked potential (EEP) was successfully recorded using Japanese white rabbits. These results indicate that electrical stimulation using the Pt-b stimulus electrode array can restore visual sensation.

  5. 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. PMID:26983941

  6. 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.

  7. Response profiles of murine spiral ganglion neurons on multi-electrode arrays

    NASA Astrophysics Data System (ADS)

    Hahnewald, Stefan; Tscherter, Anne; Marconi, Emanuele; Streit, Jürg; Widmer, Hans Rudolf; Garnham, Carolyn; Benav, Heval; Mueller, Marcus; Löwenheim, Hubert; Roccio, Marta; Senn, Pascal

    2016-02-01

    Objective. Cochlear implants (CIs) have become the gold standard treatment for deafness. These neuroprosthetic devices feature a linear electrode array, surgically inserted into the cochlea, and function by directly stimulating the auditory neurons located within the spiral ganglion, bypassing lost or not-functioning hair cells. Despite their success, some limitations still remain, including poor frequency resolution and high-energy consumption. In both cases, the anatomical gap between the electrode array and the spiral ganglion neurons (SGNs) is believed to be an important limiting factor. The final goal of the study is to characterize response profiles of SGNs growing in intimate contact with an electrode array, in view of designing novel CI devices and stimulation protocols, featuring a gapless interface with auditory neurons. Approach. We have characterized SGN responses to extracellular stimulation using multi-electrode arrays (MEAs). This setup allows, in our view, to optimize in vitro many of the limiting interface aspects between CIs and SGNs. Main results. Early postnatal mouse SGN explants were analyzed after 6-18 days in culture. Different stimulation protocols were compared with the aim to lower the stimulation threshold and the energy needed to elicit a response. In the best case, a four-fold reduction of the energy was obtained by lengthening the biphasic stimulus from 40 μs to 160 μs. Similarly, quasi monophasic pulses were more effective than biphasic pulses and the insertion of an interphase gap moderately improved efficiency. Finally, the stimulation with an external electrode mounted on a micromanipulator showed that the energy needed to elicit a response could be reduced by a factor of five with decreasing its distance from 40 μm to 0 μm from the auditory neurons. Significance. This study is the first to show electrical activity of SGNs on MEAs. Our findings may help to improve stimulation by and to reduce energy consumption of CIs and

  8. Amperometric biosensor based on 3D ordered freestanding porous Pt nanowire array electrode.

    PubMed

    Wang, Yunli; Zhu, Yingchun; Chen, Jingjing; Zeng, Yi

    2012-09-28

    A three-dimensionally (3D) ordered freestanding porous platinum (Pt) nanowire array electrode (PPNWAE) with pores of several nanometers in size and a Pt nanowire array electrode (PNWAE) without pores were facilely fabricated by metal electrodeposition and direct integration with a Pt disk electrode. The unusual PPNWAE with high active area showed excellent sensitivity (0.36 mA cm(-2) mM(-1)) and a wide detection range (4.5 μM-27.1 mM) to hydrogen peroxide (H(2)O(2)). A glucose oxidase (GOD)-based biosensor (PPNWAE/GOD) with a considerably wide detection range (4.5 μM-189.5 mM) to glucose was demonstrated. Furthermore, a lower detection limit, higher sensitivity and smaller value of Michaelis-Menten constant k(m) were recorded for PPNWAE-based biosensors compared with PNWAE-based biosensors. Particularly, the response current to glucose of PPNWAE/GOD was ca. 100% higher than that of PNWAE/GOD and the response current to H(2)O(2) of PPNWAE was ca. 50% higher than that of PNWAE, owing to the granular and rougher porous nanowire surface enabling greater bioactivity for GOD. The selectivity of PPNWAE/GOD glucose biosensor was also estimated. PMID:22898987

  9. Template preparation of Pt-Ru and Pt nanowire array electrodes on a Ti/Si substrate for methanol electro-oxidation

    NASA Astrophysics Data System (ADS)

    Zhao, Guang-Yu; Xu, Cai-Ling; Guo, Dao-Jun; Li, Hua; Li, Hu-Lin

    Pt and Pt-Ru nanowire array electrodes were obtained by dc (direct current) electrodeposition of Pt and Ru into the pores of an anodic aluminum oxide (AAO) template on a Ti/Si substrate. Transmission electron microscope (TEM) examination showed all the nanowires had a uniform diameter of about 30 nm. The brush shaped Pt and Pt-Ru nanowire array electrodes could be seen clearly by scanning electron microscope. Pt and Pt-Ru nanowire array electrodes gave the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure. The electro-oxidation of methanol on these electrodes was investigated at room temperature using cyclic voltammetry. The results demonstrated that the alloy nanowire array electrode was catalytically more active than a pure platinum nanowire array electrode and the Pt-Ru nanowire array electrode may have good potential for applications in portable fuel cell power sources.

  10. 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.

  11. Large current difference in Au-coated vertical silicon nanowire electrode array with functionalization of peptides

    PubMed Central

    2013-01-01

    Au-coated vertical silicon nanowire electrode array (VSNEA) was fabricated using a combination of bottom-up and top-down approaches by chemical vapor deposition and complementary metal-oxide-semiconductor process for biomolecule sensing. To verify the feasibility for the detection of biomolecules, Au-coated VSNEA was functionalized using peptides having a fluorescent probe. Cyclic voltammograms of the peptide-functionalized Au-coated VSNEA show a steady-state electrochemical current behavior. Because of the critically small dimension and vertically aligned nature of VSNEA, the current density of Au-coated VSNEA was dramatically higher than that of Au film electrodes. Au-coated VSNEA further showed a large current difference with and without peptides that was nine times more than that of Au film electrodes. These results indicate that Au-coated VSENA is highly effective device to detect peptides compared to conventional thin-film electrodes. Au-coated VSNEA can also be used as a divergent biosensor platform in many applications. PMID:24279451

  12. Large current difference in Au-coated vertical silicon nanowire electrode array with functionalization of peptides

    NASA Astrophysics Data System (ADS)

    Kim, Ilsoo; Kim, So-Eun; Han, Sanghun; Kim, Hyungsuk; Lee, Jaehyung; Jeong, Du-Won; Kim, Ju-Jin; Lim, Yong-beom; Choi, Heon-Jin

    2013-11-01

    Au-coated vertical silicon nanowire electrode array (VSNEA) was fabricated using a combination of bottom-up and top-down approaches by chemical vapor deposition and complementary metal-oxide-semiconductor process for biomolecule sensing. To verify the feasibility for the detection of biomolecules, Au-coated VSNEA was functionalized using peptides having a fluorescent probe. Cyclic voltammograms of the peptide-functionalized Au-coated VSNEA show a steady-state electrochemical current behavior. Because of the critically small dimension and vertically aligned nature of VSNEA, the current density of Au-coated VSNEA was dramatically higher than that of Au film electrodes. Au-coated VSNEA further showed a large current difference with and without peptides that was nine times more than that of Au film electrodes. These results indicate that Au-coated VSENA is highly effective device to detect peptides compared to conventional thin-film electrodes. Au-coated VSNEA can also be used as a divergent biosensor platform in many applications.

  13. Three-dimensional nanotube electrode arrays for hierarchical tubular structured high-performance pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Gao, Yuan; Lin, Yuanjing; Chen, Jiaqi; Lin, Qingfeng; Wu, Yue; Su, Wenjun; Wang, Wenli; Fan, Zhiyong

    2016-07-01

    Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with high uniformity. The large surface area of such a structure leads to remarkable surface area enhancement up to 51.8 times compared to a planar structure. Combining with electrochemically deposited manganese dioxide (MnO2) nanoflakes on the inner side wall of the FTO nanotubes, the unique hierarchical tubular structured pseudocapacitor electrode demonstrated the highest areal capacitance of 193.8 mF cm-2 at the scan rate of 5 mV s-1 and 184 mF cm-2 at the discharge current density of 0.6 mA cm-2, which is 18.5 times that of a planar electrode. And it also showed a volumetric capacitance of 112.6 F cm-3 at the scan rate of 5 mV s-1 and 108.8 F cm-3 at the discharge current density of 0.6 mA cm-2. In addition, the cyclic stability test also indicated that a nanostructured pseudocapacitive electrode has a much larger capacitance retention after 3000 cycles of the charge-discharge process compared with a planar electrode, primarily due to the mechanical stability of the nanostructure. Moreover, pseudocapacitor device fabrication based on such electrodes shows the volumetric capacitance of 17.5 F cm-3, and the highest specific energy of 1.56 × 10-3 Wh cm-3. With the merit of facile fabrication procedures and largely enhanced electrochemical performance, such a 3-D structure has high potency for energy storage systems for a wide range of practical applications.Ordered three-dimensional (3-D) tubular arrays are highly attractive candidates for high performance pseudocapacitor electrodes. Here, we report 3-D fluorine doped tin oxide (FTO) tubular arrays fabricated by a cost-effective ultrasonic spray pyrolysis (USP) method in anodic aluminum oxide (AAO) channels with

  14. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array.

    PubMed

    Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-Beom; Choi, Heon-Jin

    2016-12-01

    In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes. PMID:27448026

  15. Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyung; Hong, Min-Ho; Han, Sanghun; Na, Jukwan; Kim, Ilsoo; Kwon, Yong-Joon; Lim, Yong-beom; Choi, Heon-Jin

    2016-07-01

    In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes.

  16. The origin of spontaneous synchronized burst in cultured neuronal networks based on multi-electrode arrays.

    PubMed

    Chen, Chuanping; Chen, Lin; Lin, Yunsheng; Zeng, Shaoqun; Luo, Qingming

    2006-08-01

    Many neural networks in mammalian central nervous system (CNS) fire single spike and complex spike burst. In fact, the conditions for triggering burst are not well understood. In the paper multi-electrode arrays (MEA) are used to record the spontaneous electrophysiological activities of cultured rat hippocampal neuronal network for a long time. After about 3 weeks culture, a transition from single spike to burst is observed in several networks. All of these spikes fire quickly before burst begins. The firing rate during the burst is lower than that just before the burst, but differences of inter-spike intervals (ISIs) between two firing patterns are not clear. Moreover, the electrical activities on neighboring electrodes show strong synchrony during the burst activities. In a word, the generation of the burst requires that network should have a sufficient level of excitation as well as a balance of synaptic inhibition. PMID:16533555

  17. Liquid-crystal micro-lens array with two-divided and tetragonally hole-patterned electrodes.

    PubMed

    Kawamura, Marenori; Nakamura, Kento; Sato, Susumu

    2013-11-01

    We propose a liquid crystal (LC) micro-lens array with the structure of two-divided and tetragonally hole-patterned electrodes. Each LC cell in the lens array behaves like cylindrical or spherical lens properties by electrically adjusting the applied voltages. The LC micro-lens array is useful for tuning optical properties such a focal length and deflection angle of a light emitting diode (LED) illumination system. PMID:24216873

  18. Packaging of large-area individually addressable micromirror arrays for the next generation space telescope

    NASA Astrophysics Data System (ADS)

    Lu, GuoQuan; Calata, J.; Wen, S.; Dutta, Sanghamitra B.; Zheng, Yun; Stahl, C.; Shu, Peter K.

    2002-04-01

    One of NASA's challenging projects for advancing the exploration of space is the development and deployment of the Next Generation Space Telescope (NGST) for superseding the existing Hubble Space Telescope. The NGST will be equipped with several camera/spectrometer systems including a 0.6 to 5 micron Multi-Object-Spectrometer. To selectively direct light rays from different regions of space into the spectrometer, an option is to use individually addressable micro-electro-mechanical-mirror arrays serving as the slit mask for the spectrometer. The NASA team at Goddard Space Flight Center has designed an integrated micro-mirror array/CMOS driver chip that can meet the system requirements. The fabrication and testing of prototype chips have yielded promising results. To build the entire MEMS- based slit mask, a design requires accurate placement and alignment of four large (at least 9 cm X 9 cm) pieces of the integrated chips in a 2X2 mosaic pattern. In addition, the mask will have to function at temperatures below 40 K. These requirements pose a serious challenge to the packaging of these integrated MEMS chips. In this paper, we discuss a concept for attaching and aligning the large- area MEMS chips into the 2X2 mask and interconnecting it to the rest of the system. The concept makes use of the flip-chip technology to bump-bond the large chips onto a silicon substrate such that the concern for global thermo- mechanical stresses due to mismatched coefficients of thermal expansion between chip and substrate is eliminated. It also makes use of the restoring force of the solder bumps during reflow to self-align the chips. A critical experiment involving the use of 'mechanical' chips with two-dimensional arrays of bonding pads was carried out to evaluate the feasibility of the packaging concept. Preliminary results indicate that the chips can be attached to form a closely packed mosaic pattern with a relative tilt angle between the chips to less than 0.05 degree, which is

  19. Ordered Polypyrrole Nanowire Arrays Grown on a Carbon Cloth Substrate for a High-Performance Pseudocapacitor Electrode.

    PubMed

    Huang, Zi-Hang; Song, Yu; Xu, Xin-Xin; Liu, Xiao-Xia

    2015-11-18

    Highly aligned nanoarchitecture arrays directly grown on conducting substrates open up a new direction to accelerate Faradaic reactions for charge storage as well as address "dead volume" limitations for high-performance pseudocapacitor electrodes. Here we reported the electrochemical fabrication of well-ordered polypyrrole (PPy) nanowire arrays (NWAs) on surfaces of carbon fibers in an untreated carbon cloth to construct hierarchical structures constituted by the three-dimensional conductive carbon fiber skeleton and the atop well-ordered electroactive polymer nanowires. The morphologies, wetting behaviors, and charge-storage performances of the polymer were investigated by scanning electron microscopy, transmission electron microscopy, contact-angle measurement, cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The well-ordered PPy NWA electrode exhibited a high specific capacitance of 699 F/g at 1 A/g with excellent rate capability, and 92.4% and 81.5% of its capacitance could be retained at 10 and 20 A/g, respectively. An extremely high energy density of 164.07 Wh/kg could be achieved by the PPy NWAs at a power density of 0.65 kW/kg. It also displayed a quite high energy density of 133.79 Wh/kg at a high power density of 13 kW/kg. The assembled symmetric supercapacitor of PPy NWAs//PPy NWAs also exhibited excellent rate capability, and only 19% of its energy density decreased when the power density increased 20 times from 0.65 to 13 kW/kg. PMID:26509281

  20. Wireless electrochemiluminescence bipolar electrode array for visualized genotyping of single nucleotide polymorphism.

    PubMed

    Khoshfetrat, Seyyed Mehdi; Ranjbari, Mitra; Shayan, Mohsen; Mehrgardi, Masoud A; Kiani, Abolfazl

    2015-08-18

    The development of simple, inexpensive, hand-held, user-friendly biosensor for high throughput and multiplexed genotyping of various single nucleotide polymorphisms (SNPs) in a single run experiment by a nonspecialist user is the main challenge in the analysis of DNA. Visualizing the signal and possibility to monitor SNPs by a digital camera opens a new horizon for the routine applications. In the present manuscript, a novel wireless electrochemiluminescence (ECL) DNA array is introduced for the visualized genotyping of different SNPs on the basis of ECL of luminol/hydrogen peroxide system on a bipolar electrode (BPE) array platform. After modification of anodic poles of the array with the DNA probe and its hybridization with the targets, genotyping of various SNPs is carried out by exposing the array to different monobase modified luminol-platinum nanoparticles (M-L-PtNPs). Upon the hybridization of M-L-PtNPs to mismatch sites, the ECL of luminol is followed using a photomultiplier tube (PMT) or digital camera and the images are analyzed by ImageJ software. This biosensor can detect even thermodynamically stable SNP (G-T mismatches) in the range of 2-600 pM. Also, by combining the advantages of BPE and the high visual sensitivity of ECL, it could be easily expected to achieve sensitive screening of different SNPs. The present biosensor demonstrates the capability for the discrimination between PCR products of normal, heterozygous, and homozygous beta thalassemia genetic disorders. PMID:26176414

  1. An Evaluation of Global Address Space Languages: Co-Array Fortran and Unified Parallel C

    SciTech Connect

    Coarfa, Cristian; Dotsenko, Yuri; Mellor-Crummey, John M.; Cantonnet, Franois; El-Ghazawi, Tarek; Mohanti, Ashrujit; Yao, Yiyi; Chavarría-Miranda, Daniel

    2005-06-10

    Co-array Fortran (CAF) and Unified Parallel C (UPC) are two emerging languages for single-program, multiple-data global address space programming. These languages boost programmer productivity by providing shared variables for communication instead of message passing. However, the performance of these emerging languages still has room for improvement. In this paper, we study the performance of variants of the NAS MG, CG, SP, and BT benchmarks on several modern cluster architectures to identify challenges that must be met to deliver top performance. We compare CAF and UPC variants of these programs with the original Fortran+MPI code. Today, CAF and UPC programs deliver scalable performance on clusters only when written to use bulk communication. However, our experiments uncovered some significant performance bottlenecks limiting UPC performance on all platforms. We account for the root causes of these performance anomalies and show that they can be remedied with additional compiler improvements, in particular we show that many of these obstacles can be resolved with adequate optimizations by the backend C compilers.

  2. 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

  3. Curved Microneedle Array-Based sEMG Electrode for Robust Long-Term Measurements and High Selectivity.

    PubMed

    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

  4. Manipulating location, polarity, and outgrowth length of neuron-like pheochromocytoma (PC-12) cells on patterned organic electrode arrays.

    PubMed

    Hsiao, Yu-Sheng; Lin, Chung-Chih; Hsieh, Hsin-Jui; Tsai, Shih-Min; Kuo, Chiung-Wen; Chu, Chih-Wei; Chen, Peilin

    2011-11-01

    In this manuscript, we describe a biocompatible organic electrode system, comprising poly(3,4-ethylenedioxythiophene) (PEDOT) microelectrode arrays on indium tin oxide (ITO) glass, that can be used to regulate the neuron type, location, polarity, and outgrown length of neuron-like cells (PC-12). We fabricated a PEDOT microelectrode array with four different sizes (flat; 20, 50, and 100 μm) through electrochemical polymerization. Extracellular matrix proteins absorbed well on these organic electrodes; cells absorbed selectively on the organic electrodes when we used polyethylene oxide/polypropylene oxide/polyethylene oxide triblock copolymers (PEO/PPO/PEO, Pluronic™ F108) as the anti-adhesive coating. In this system, the neurite polarities and neuron types could be manipulated by varying the width of the PEDOT microelectrode arrays. On the unpatterned PEDOT electrode, PC-12 cells were randomly polarized, with approximately 80% having multi-polar cell types. In contrast, when we cultured PC-12 cells on the 20 μm wide PEDOT line array, the neurites aligned along the direction of the organic electrodes, with the percentage of uni- and bipolar PC-12 cells increasing to greater than 90%. The outgrowth of neurites on the microelectrodes was promoted by ~60% with an applied electrical stimulation. Therefore, these electroactive PEDOT microelectrode arrays have potential for use in tissue engineering related to the development and regeneration of mammalian nervous systems. PMID:21922117

  5. 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

  6. Pt-Pb nanowire array electrode for enzyme-free glucose detection.

    PubMed

    Bai, Yu; Sun, Yingying; Sun, Changqing

    2008-12-01

    Pt-Pb nanowire array was directly synthesized by electrochemical deposition of Pt-Pb alloy into the pores of microporous polycarbonate template and subsequent chemical etching of the template. The morphology and the composition of the Pt-Pb nanowires were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively. Cyclic voltammetry (CV) was used to evaluate the electrochemical performance of the Pt-Pb nanowire array electrode (Pt-PbNAE). Direct glucose oxidation on Pt-PbNAE was investigated in detail by discussing the effect of the structure and materials of the electrode on electrocatalytic oxidation of glucose. As a result, we found that the Pt-PbNAE with a three-dimensional structure exhibited high electrocatalytic activity to glucose oxidation in neutral condition and could be used for the development of nonenzymatic glucose sensor. To effectively avoid the interference coming from ascorbic acid, a negative potential of -0.20V was chosen for glucose detection, and the sensitivity of the sensor to glucose oxidation was 11.25 microAmM(-1)cm(-2) with a linearity up to 11 mM, and a detection limit of 8 microM (signal-to-noise ratio of 3). PMID:18619831

  7. Recording sensory and motor information from peripheral nerves with Utah Slanted Electrode Arrays.

    PubMed

    Clark, Gregory A; Ledbetter, Noah M; Warren, David J; Harrison, Reid R

    2011-01-01

    Recording and stimulation via high-count penetrating microelectrode arrays implanted in peripheral nerves may help restore precise motor and sensory function after nervous system damage or disease. Although previous work has demonstrated safety and relatively successful stimulation for long-term implants of 100-electrode Utah Slanted Electrode Arrays (USEAs) in feline sciatic nerve [1], two major remaining challenges were 1) to maintain viable recordings of nerve action potentials long-term, and 2) to overcome contamination of unit recordings by myoelectric (EMG) activity in awake, moving animals. In conjunction with improvements to USEAs themselves, we have redesigned several aspects of our USEA containment and connector systems. Although further increases in unit yield and long-term stability remain desirable, here we report considerable progress toward meeting both of these goals: We have successfully recorded unit activity from USEAs implanted intrafascicularly in sciatic nerve for periods up to 4 months (the terminal experimental time point), and we have developed a containment system that effectively eliminates or substantially reduces EMG contamination of unit recordings in the moving animal. In addition, we used a 100-channel wireless recording integrated circuit attached to implanted USEAs to transmit broadband or spike-threshold data from nerve. Neural data thusly obtained during imposed limb movements were decoded blindly to drive a virtual prosthetic limb in real time. These results support the possibility of using USEAs in peripheral nerves to provide motor control and cutaneous or proprioceptive sensory feedback in individuals after limb loss or spinal cord injury. PMID:22255372

  8. Wall-like hierarchical metal oxide nanosheet arrays grown on carbon cloth for excellent supercapacitor electrodes.

    PubMed

    Huang, Zongyu; Zhang, Zhen; Qi, Xiang; Ren, Xiaohui; Xu, Guanghua; Wan, Pengbo; Sun, Xiaoming; Zhang, Han

    2016-07-21

    Recently, considerable efforts have been made to satisfy the future requirements of electrochemical energy storage using novel functional electrode materials. Binary transition metal oxides (BTMOs) possess multiple oxidation states that enable multiple redox reactions, showing higher supercapacitive properties than single component metal oxides. In this work, a facile hydrothermal method is provided for the synthesis of wall-like hierarchical metal oxide MMoO4 (M = Ni, Co) nanosheet arrays, which are directly grown on flexible carbon cloth for use as advanced binder-free electrodes for supercapacitors. By virtue of their intriguing structure, the resulted active material nanosheets with a high specific surface area can provide a large electroactive region, which could facilitate easy accession of electrolyte ions and fast charge transport, resulting in an enhanced electrochemical performance. Separately, the as-synthesized MMoO4 (M = Ni, Co) samples have exhibited superior specific capacitances (1483 F g(-1) of NiMoO4 and 452 F g(-1) of CoMoO4 at a current density of 2 A g(-1)), as well as excellent cycling stability (93.1% capacitance retention of NiMoO4 and 95.9% capacitance retention of CoMoO4 after 2000 cycles). The results show that the binder-free electrodes constructed by deposition of MMoO4 (M = Ni, Co) nanosheets on carbon cloth are promising candidates for the application of supercapacitors. PMID:27336591

  9. Imaging of CO2 plume scenarios in saline reservoirs by (non) optimized crosshole electrode arrays

    NASA Astrophysics Data System (ADS)

    Al Hagrey, S. A.; Strahser, M. H.; Rabbel, W.

    2009-12-01

    In the scope of the research project “CO2 MoPa” (modeling and parameterization of CO2 storage in deep saline formations for dimensions and risk analysis), one main task is to study the efficiency of electrical resistivity tomography in boreholes (BRT) in monitoring the subsurface distribution of CO2 sequestrated in deep saline reservoirs. Similar to ground surveys, BRT ones between a pair of borehole electrode arrays can be conducted in the tripotential quadrupole configurations of α, β and γ in vertical, lateral and horizontal modes. The circulating vertical mode is carried out within the same borehole (inhole) and between two boreholes (crosshole). The comprehensive dataset results from excluding the less stable inversion configurations from the whole set (of all possible independent non-reciprocal configurations). It should result in the best possible resolution. An optimized dataset takes into account the trade-off between spatial and temporal resolution of targets and processes. It has far less data size than the comprehensive one but almost the same resolution. Hagrey (2009) and Loke (pers. com.) extended four published 2D optimization algorithms of electrode arrays for ground surveys into BRT ones. Using an initial base dataset of the dipole-dipole configuration, the new configurations (from the remaining comprehensive dataset) with the largest increase in the model resolution matrix is added to the base dataset. After each iteration the number of arrays in the optimized dataset is increased and the procedure is repeated iteratively until the required data size is achieved. For BRT surveys between two vertical boreholes, ten (non)-standard and optimized configurations have been examined as a function of the multiparameters of, CO2 plume scenarios, burial depths, electrode configurations, aspect ratios, and forward and inversion setup constraints. In these 2.5D modeling studies problems of sharp and gradual boundaries for plume scenarios and

  10. 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.

  11. Image sensors with electrically tunable spatial resolution based on liquid crystal microlens array with three-layered patterned electrode

    NASA Astrophysics Data System (ADS)

    Tong, Qing; Zhang, Xinyu; Sang, Hongshi; Zhang, Tianxu; Xie, Changsheng

    2013-10-01

    The liquid crystal (LC) device with the circle aperture electrode can be used as a convex lens. The index of refraction of the LC lens can be easily changed by the voltage signal; the arrayed LC lens can be used in the imaging sensors. Comparing with the traditional optical lens, the LC lens has a more effective architecture. In this paper, we present an imaging sensor with a new type LC structure composed of three layers of top electrodes and a joint bottom electrode, and simulating the tunable spatial resolution architecture carried out by applying voltage signal over different ITO electrode in LC lenses coupled with arrayed imaging sensors. From the result of the simulation, we can find that changing the spatial resolution by our architecture can be achieved.

  12. Artificial Solid Electrolyte Interphase to Address the Electrochemical Degradation of Silicon Electrodes

    SciTech Connect

    Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu; Li, Juchuan

    2014-01-01

    Electrochemical degradation on Si anodes prevents them from being successfully used in lithium-ion full cells. Unlike the case of graphite anodes, natural solid electrolyte interphase (SEI) films generated from carbonate electrolyte do not self-passivate on Si and causes continuous electrolyte decomposition. In this work we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphor oxynitride (Lipon), that conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, significant effect is observed in suppressing the electrolyte decomposition, while Lipon of thinner than 40 nm has little effect. Ionic and electronic conductivity measurement reveals that the artificial SEI is effective when it is a pure ionic conductor, and the electrolyte decomposition is not suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40~50 nm. This work provides guidance for designing artificial SEI for high capacity lithium-ion battery electrodes using solid electrolyte materials.

  13. Artificial solid electrolyte interphase to address the electrochemical degradation of silicon electrodes.

    PubMed

    Li, Juchuan; Dudney, Nancy J; Nanda, Jagjit; Liang, Chengdu

    2014-07-01

    Electrochemical degradation on silicon (Si) anodes prevents them from being successfully used in lithium (Li)-ion battery full cells. Unlike the case of graphite anodes, the natural solid electrolyte interphase (SEI) films generated from carbonate electrolytes do not self-passivate on Si, causing continuous electrolyte decomposition and loss of Li ions. In this work, we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphorus oxynitride (Lipon), which conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, a significant effect is observed in suppressing electrolyte decomposition, while Lipon of thinner than 40 nm has a limited effect. Ionic and electronic conductivity measurements reveal that the artificial SEI is effective when it is a pure ionic conductor, but electrolyte decomposition is only partially suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40-50 nm. This work provides guidance for designing artificial SEI films for high-capacity Li-ion battery electrodes using solid electrolyte materials. PMID:24926882

  14. A novel fabrication method for a 64 × 64 matrix-addressable GaN-based micro-LED array

    NASA Astrophysics Data System (ADS)

    Jeon, C.-W.; Choi, H. W.; Dawson, M. D.

    2003-11-01

    The fabrication and performance of GaN-based micro-light emitting diode (-LED) arrays with 64 × 64 elements is reported. The diameter of each element is 20 m and center-to-center spacing 30 m, giving an overall active area of the arrays of 80425 m2. Through a novel fabrication approach including a isotropic dry etching and a self-aligned isolation technique, we could easily obtain an interconnection for a matrix-addressable array device. The arrays emit >50 W per element at 3 mA drive current. Adopting a spreading metal as a p-contact, the turn-on voltage was lowered down to 3.4 V. (

  15. Enhancement of non-invasive recording of electroenterogram by means of a flexible array of concentric ring electrodes.

    PubMed

    Garcia-Casado, J; Zena-Gimenez, V; Prats-Boluda, G; Ye-Lin, Y

    2014-03-01

    Monitoring intestinal myoelectrical activity by electroenterogram (EEnG) would be of great clinical interest for diagnosing gastrointestinal pathologies and disorders. However, surface EEnG recordings are of very low amplitude and can be severely affected by baseline drifts and respiratory and electrocardiographic (ECG) interference. In this work, a flexible array of concentric ring electrodes was developed and tested to determine whether it can provide surface EEnG signals of better quality than bipolar recordings from conventional disc electrodes. With this aim, sixteen healthy subjects in a fasting state (>8 h) underwent recording. The capability of detecting intestinal pacemaker activity (slow wave) and the influence of physiological interferences were studied. The signals obtained from the concentric ring electrodes proved to be more robust to ECG and respiratory interference than those from conventional disc electrodes. The results also show that intestinal EEnG components such as the slow wave can be more easily identified by the proposed system based on a flexible array of concentric ring electrodes. The developed active electrode array could be a very valuable tool for non-invasive diagnosis of disease states such as ischemia and motility disorders of the small bowel which are known to alter the normal enteric slow wave activity. PMID:24232692

  16. Minimally invasive endovascular stent-electrode array for high-fidelity, chronic recordings of cortical neural activity.

    PubMed

    Oxley, Thomas J; Opie, Nicholas L; John, Sam E; Rind, Gil S; Ronayne, Stephen M; Wheeler, Tracey L; Judy, Jack W; McDonald, Alan J; Dornom, Anthony; Lovell, Timothy J H; Steward, Christopher; Garrett, David J; Moffat, Bradford A; Lui, Elaine H; Yassi, Nawaf; Campbell, Bruce C V; Wong, Yan T; Fox, Kate E; Nurse, Ewan S; Bennett, Iwan E; Bauquier, Sébastien H; Liyanage, Kishan A; van der Nagel, Nicole R; Perucca, Piero; Ahnood, Arman; Gill, Katherine P; Yan, Bernard; Churilov, Leonid; French, Christopher R; Desmond, Patricia M; Horne, Malcolm K; Kiers, Lynette; Prawer, Steven; Davis, Stephen M; Burkitt, Anthony N; Mitchell, Peter J; Grayden, David B; May, Clive N; O'Brien, Terence J

    2016-03-01

    High-fidelity intracranial electrode arrays for recording and stimulating brain activity have facilitated major advances in the treatment of neurological conditions over the past decade. Traditional arrays require direct implantation into the brain via open craniotomy, which can lead to inflammatory tissue responses, necessitating development of minimally invasive approaches that avoid brain trauma. Here we demonstrate the feasibility of chronically recording brain activity from within a vein using a passive stent-electrode recording array (stentrode). We achieved implantation into a superficial cortical vein overlying the motor cortex via catheter angiography and demonstrate neural recordings in freely moving sheep for up to 190 d. Spectral content and bandwidth of vascular electrocorticography were comparable to those of recordings from epidural surface arrays. Venous internal lumen patency was maintained for the duration of implantation. Stentrodes may have wide ranging applications as a neural interface for treatment of a range of neurological conditions. PMID:26854476

  17. 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

  18. Performance assessments of vertically aligned carbon nanotubes multi-electrode arrays using Cath.a-differentiated (CAD) cells

    NASA Astrophysics Data System (ADS)

    Jeong, Du Won; Jung, Jongjin; Kim, Gook Hwa; Yang, Cheol-Soo; Kim, Ju Jin; Jung, Sang Don; Lee, Jeong-O.

    2015-08-01

    In this work, Cath.a-differentiated (CAD) cells were used in place of primary neuronal cells to assess the performance of vertically aligned carbon nanotubes (VACNTs) multi-electrode arrays (MEA). To fabricate high-performance MEA, VACNTs were directly grown on graphene/Pt electrodes via plasma enhanced chemical deposition technique. Here, graphene served as an intermediate layer lowering contact resistance between VACNTs and Pt electrode. In order to lower the electrode impedance and to enhance the cell adhesion, VACNTs-MEAs were treated with UV-ozone for 20 min. Impedance of VACNTs electrode at 1 kHz frequency exhibits a reasonable value (110 kΩ) for extracellular signal recording, and the signal to noise ratio the is good enough to measure low signal amplitude (15.7). Spontaneous firing events from CAD cells were successfully measured with VACNTs MEAs that were also found to be surprisingly robust toward the biological interactions.

  19. Performance assessments of vertically aligned carbon nanotubes multi-electrode arrays using Cath.a-differentiated (CAD) cells.

    PubMed

    Jeong, Du Won; Jung, Jongjin; Kim, Gook Hwa; Yang, Cheol-Soo; Kim, Ju Jin; Jung, Sang Don; Lee, Jeong-O

    2015-08-21

    In this work, Cath.a-differentiated (CAD) cells were used in place of primary neuronal cells to assess the performance of vertically aligned carbon nanotubes (VACNTs) multi-electrode arrays (MEA). To fabricate high-performance MEA, VACNTs were directly grown on graphene/Pt electrodes via plasma enhanced chemical deposition technique. Here, graphene served as an intermediate layer lowering contact resistance between VACNTs and Pt electrode. In order to lower the electrode impedance and to enhance the cell adhesion, VACNTs-MEAs were treated with UV-ozone for 20 min. Impedance of VACNTs electrode at 1 kHz frequency exhibits a reasonable value (110 kΩ) for extracellular signal recording, and the signal to noise ratio the is good enough to measure low signal amplitude (15.7). Spontaneous firing events from CAD cells were successfully measured with VACNTs MEAs that were also found to be surprisingly robust toward the biological interactions. PMID:26222018

  20. Ag nanoparticle-deposited TiO2 nanotube arrays for electrodes of Dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Kawamura, Go; Ohmi, Hayato; Tan, Wai Kian; Lockman, Zainovia; Muto, Hiroyuki; Matsuda, Atsunori

    2015-05-01

    Dye-sensitized solar cells composed of a photoanode of Ag nanoparticle (NP)-deposited TiO2 nanotube (TNT) arrays were fabricated. The TNT arrays were prepared by anodizing Ti films on fluorine-doped tin oxide (FTO)-coated glass substrates. Efficient charge transportation through the ordered nanostructure of TNT arrays should be carried out compared to conventional particulate TiO2 electrodes. However, it has been a big challenge to grow TNT arrays on FTO glass substrates with the lengths needed for sufficient light-harvesting (tens of micrometers). In this work, we deposited Ag nanoparticles (NPs) on the wall of TNT arrays to enhance light-harvesting property. Dye-sensitized solar cells with these Ag NP-deposited TNT arrays yielded a higher power conversion efficiency (2.03 %) than those without Ag NPs (1.39 %).

  1. Simplified calibration of single-plunge bipolar electrode array for field measurement during defibrillation.

    PubMed

    Deale, O Carlton; Ng, Kwong T; Kim-Van Housen, Ellen J; Lerman, Bruce B

    2002-10-01

    In an earlier study, the authors presented a calibration technique for a triaxial bipolar electrode array (EA) that used 72 data points collected during a global sweep of the electric field vector relative to the EA axes. Although necessary for the initial characterization of the EAs, this data requirement has to be significantly reduced for the technique to become a practical tool. Therefore, in the present study, an analysis is performed to determine the relation between the number of data points used in the calibration and the mean root-mean-square error. The analysis shows that 18 data points can produce results nearly identical to those obtained with the 72-point calibration, thus reducing the required amount of data fourfold. PMID:12374347

  2. Innervation zones of fasciculating motor units: observations by a linear electrode array

    PubMed Central

    Jahanmiri-Nezhad, Faezeh; Barkhaus, Paul E.; Rymer, William Z.; Zhou, Ping

    2015-01-01

    This study examines the innervation zone (IZ) in the biceps brachii muscle in healthy subjects and those with amyotrophic lateral sclerosis (ALS) using a 20-channel linear electromyogram (EMG) electrode array. Raster plots of individual waveform potentials were studied to estimate the motor unit IZ. While this work mainly focused on fasciculation potentials (FPs), a limited number of motor unit potentials (MUPs) from voluntary activity of 12 healthy and seven ALS subjects were also examined. Abnormal propagation of MUPs and scattered IZs were observed in fasciculating units, compared with voluntarily activated MUPs in healthy and ALS subjects. These findings can be related to muscle fiber reinnervation following motor neuron degeneration in ALS and the different origin sites of FPs compared with voluntary MUPs. PMID:26029076

  3. Electrostatically focused addressable field emission array chips (AFEA's) for high-speed massively parallel maskless digital E-beam direct write lithography and scanning electron microscopy

    DOEpatents

    Thomas, Clarence E.; Baylor, Larry R.; Voelkl, Edgar; Simpson, Michael L.; Paulus, Michael J.; Lowndes, Douglas H.; Whealton, John H.; Whitson, John C.; Wilgen, John B.

    2002-12-24

    Systems and methods are described for addressable field emission array (AFEA) chips. A method of operating an addressable field-emission array, includes: generating a plurality of electron beams from a pluralitly of emitters that compose the addressable field-emission array; and focusing at least one of the plurality of electron beams with an on-chip electrostatic focusing stack. The systems and methods provide advantages including the avoidance of space-charge blow-up.

  4. Wall-like hierarchical metal oxide nanosheet arrays grown on carbon cloth for excellent supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Huang, Zongyu; Zhang, Zhen; Qi, Xiang; Ren, Xiaohui; Xu, Guanghua; Wan, Pengbo; Sun, Xiaoming; Zhang, Han

    2016-07-01

    Recently, considerable efforts have been made to satisfy the future requirements of electrochemical energy storage using novel functional electrode materials. Binary transition metal oxides (BTMOs) possess multiple oxidation states that enable multiple redox reactions, showing higher supercapacitive properties than single component metal oxides. In this work, a facile hydrothermal method is provided for the synthesis of wall-like hierarchical metal oxide MMoO4 (M = Ni, Co) nanosheet arrays, which are directly grown on flexible carbon cloth for use as advanced binder-free electrodes for supercapacitors. By virtue of their intriguing structure, the resulted active material nanosheets with a high specific surface area can provide a large electroactive region, which could facilitate easy accession of electrolyte ions and fast charge transport, resulting in an enhanced electrochemical performance. Separately, the as-synthesized MMoO4 (M = Ni, Co) samples have exhibited superior specific capacitances (1483 F g-1 of NiMoO4 and 452 F g-1 of CoMoO4 at a current density of 2 A g-1), as well as excellent cycling stability (93.1% capacitance retention of NiMoO4 and 95.9% capacitance retention of CoMoO4 after 2000 cycles). The results show that the binder-free electrodes constructed by deposition of MMoO4 (M = Ni, Co) nanosheets on carbon cloth are promising candidates for the application of supercapacitors.Recently, considerable efforts have been made to satisfy the future requirements of electrochemical energy storage using novel functional electrode materials. Binary transition metal oxides (BTMOs) possess multiple oxidation states that enable multiple redox reactions, showing higher supercapacitive properties than single component metal oxides. In this work, a facile hydrothermal method is provided for the synthesis of wall-like hierarchical metal oxide MMoO4 (M = Ni, Co) nanosheet arrays, which are directly grown on flexible carbon cloth for use as advanced binder

  5. Electrochemical signal amplification for immunosensor based on 3D interdigitated array electrodes.

    PubMed

    Han, Donghoon; Kim, Yang-Rae; Kang, Chung Mu; Chung, Taek Dong

    2014-06-17

    We devised an electrochemical redox cycling based on three-dimensional interdigitated array (3D IDA) electrodes for signal amplification to enhance the sensitivity of chip-based immunosensors. The 3D IDA consists of two closely spaced parallel indium tin oxide (ITO) electrodes that are positioned not only on the bottom but also the ceiling, facing each other along a microfluidic channel. We investigated the signal intensities from various geometric configurations: Open-2D IDA, Closed-2D IDA, and 3D IDA through electrochemical experiments and finite-element simulations. The 3D IDA among the four different systems exhibited the greatest signal amplification resulting from efficient redox cycling of electroactive species confined in the microchannel so that the faradaic current was augmented by a factor of ∼100. We exploited the enhanced sensitivity of the 3D IDA to build up a chronocoulometric immunosensing platform based on the sandwich enzyme-linked immunosorbent assay (ELISA) protocol. The mouse IgGs on the 3D IDA showed much lower detection limits than on the Closed-2D IDA. The detection limit for mouse IgG measured using the 3D IDA was ∼10 fg/mL, while it was ∼100 fg/mL for the Closed-2D IDA. Moreover, the proposed immunosensor system with the 3D IDA successfully worked for clinical analysis as shown by the sensitive detection of cardiac troponin I in human serum down to 100 fg/mL. PMID:24842332

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

    PubMed Central

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

    2016-01-01

    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. PMID:27478567

  7. Multi-electrode Array Recordings of Human Epileptic Postoperative Cortical Tissue

    PubMed Central

    Dossi, Elena; Blauwblomme, Thomas; Nabbout, Rima; Huberfeld, Gilles; Rouach, Nathalie

    2014-01-01

    Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which disrupt normal brain function. Despite treatment with currently available antiepileptic drugs targeting neuronal functions, one third of patients with epilepsy are pharmacoresistant. In this condition, surgical resection of the brain area generating seizures remains the only alternative treatment. Studying human epileptic tissues has contributed to understand new epileptogenic mechanisms during the last 10 years. Indeed, these tissues generate spontaneous interictal epileptic discharges as well as pharmacologically-induced ictal events which can be recorded with classical electrophysiology techniques. Remarkably, multi-electrode arrays (MEAs), which are microfabricated devices embedding an array of spatially arranged microelectrodes, provide the unique opportunity to simultaneously stimulate and record field potentials, as well as action potentials of multiple neurons from different areas of the tissue. Thus MEAs recordings offer an excellent approach to study the spatio-temporal patterns of spontaneous interictal and evoked seizure-like events and the mechanisms underlying seizure onset and propagation. Here we describe how to prepare human cortical slices from surgically resected tissue and to record with MEAs interictal and ictal-like events ex vivo. PMID:25407747

  8. Compliant bipolar electrostatic gripper with micropillar electrodes array for manipulation at macroscale

    NASA Astrophysics Data System (ADS)

    Dhelika, Radon; Hemthavy, Pasomphone; Takahashi, Kunio; Saito, Shigeki

    2016-05-01

    A compliant electrostatic gripper with bipolar voltage polarity for a pick-and-place manipulation is presented. The compliance, realized by the introduction of an array of micropillars which act as the electrode, extends the application of electrostatic-based gripper to manipulating fragile, rough-surfaced dielectric objects at macro scale. A prototype consisting of two arrays is developed by a chemical etching process. The experimental force is then compared with the theoretical force obtained from a simulation, showing a discrepancy between them. The sources of the discrepancy are analyzed to provide design insight for force improvement. To assess the reliability, the prototype is used for a manipulation demonstration of flat-surfaced paper. The result shows a good repeatability, and the necessary pick-up condition is confirmed. Subsequently, as the proof of the concept, another pick-up for rough-surfaced objects represented by a tissue paper with different roughness condition is also demonstrated. The effect of the rough surfaces to the generated forces is qualitatively discussed.

  9. Hybrid tandem solar cell enhanced by a metallic hole-array as the intermediate electrode.

    PubMed

    Zhang, Xuanru; Huang, Qiuping; Hu, Jigang; Knize, Randy J; Lu, Yalin

    2014-10-20

    A metallic hole-array structure was inserted into a tandem solar cell structure as an intermediate electrode, which allows a further fabrication of a novel and efficient hybrid organic-inorganic tandem solar cell. The inserted hole-array layer reflects the higher-energy photons back to the top cell, and transmits lower-energy photons to the bottom cell via the extraordinary optical transmission (EOT) effect. In this case light absorption in both top and bottom subcells can be simultaneously enhanced via both structural and material optimizations. Importantly, this new design could remove the constraints of requiring lattice-matching and current-matching between the used two cascaded subcells in a conventional tandem cell structure, and therefore, the tunnel junction could be no longer required. As an example, a novel PCBM/CIGS tandem cell was designed and investigated. A systematic modeling study was made on the structural parameter tuning, with the period ranging from a few hundreds nanometers to over one micrometer. Surface plasmon polaritons, magnetic plasmon polaritons, localized surface plasmons, and optical waveguide modes were found to participate in the EOT and the light absorption enhancement. Impressively, more than 40% integrated power enhancement can be achieved in a variable structural parameter range. PMID:25607297

  10. Three-Dimensional Microcavity Array Electrodes for High-Capacitance All-Solid-State Flexible Microsupercapacitors.

    PubMed

    Maeng, Jimin; Kim, Young-Joon; Meng, Chuizhou; Irazoqui, Pedro P

    2016-06-01

    We report novel three-dimensional (3D) microcavity array electrodes for high-capacitance all-solid-state microsupercapactiors. The microcavity arrays are formed in a polymer substrate via a plasma-assisted reactive ion etching (RIE) process and provide extra sidewall surface areas on which the active materials are grown in the form of nanofibers. This 3D structure leads to an increase in the areal capacitance by a factor of 2.56 for a 15-μm-deep cavity etching, agreeing well with the prediction. The fabricated microsupercapactiors exhibit a maximum areal capacitance of 65.1 mF cm(-2) (a volumetric capacitance of 93.0 F cm(-3)) and an energy density of 0.011 mWh cm(-2) (a volumetric energy density of 16.4 mWh cm(-3)) which substantially surpass previously reported values for all-solid-state flexible microsupercapacitors. The devices show good electrochemical stability under extended voltammetry cycles and bending cycles. It is demonstrated that they can sustain a radio frequency (rf) microsystem in a temporary absence of a power supply. These results suggest the potential utility of our 3D microsupercapactiors as miniaturized power sources in wearable and implantable medical devices. PMID:27176134

  11. 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.

  12. Microfluidic Device with Tunable Post Arrays and Integrated Electrodes for Studying Cellular Release

    PubMed Central

    Selimovic, Asmira; Erkal, Jayda L.; Spence, Dana M.; Martin, R. Scott

    2015-01-01

    In this paper, we describe the development of a planar, pillar array device that can be used to image either side of a tunable membrane, as well as sample and detect small molecules in a cell-free region of the microchip. The pores are created by sealing two parallel PDMS microchannels (a cell channel and a collector channel) over a gold pillar array (5 or 10 µm in height), with the device being characterized and optimized for small molecule cross-over while excluding a flowing cell line (here, red blood cells, RBCs). The device was characterized in terms of the flow rate dependence of cross-over of analyte and cell exclusion as well as the ability to perform amperometric detection of catechol and nitric oxide (NO) as they cross-over into the collector channel. Using catechol as the test analyte, the limits of detection (LOD) of the cross-over for the 10 µm and 5 µm pillar array heights were shown to be 50 nM and 106 nM, respectively. Detection of NO was made possible with a glassy carbon detection electrode (housed in the collector channel) modified with Pt-black and Nafion, to enhance sensitivity and selectivity, respectively. Reproducible cross-over of NO as a function of concentration resulted in a linear correlation (r2 = 0.995, 7.6 µM - 190 µM), with an LOD for NO of 230 nM on the glassy carbon-Pt-black-0.05% Nafion electrode. The applicability of the device was demonstrated by measuring the NO released from hypoxic RBCs, with the device allowing the released NO to cross-over into a cell free channel where it was detected in close to real-time. This type of device is an attractive alternative to the use of 3-dimensional devices with polycarbonate membranes, as either side of the membrane can be imaged and facile integration of electrochemical detection is possible. PMID:25105251

  13. Two-Point Stretchable Electrode Array for Endoluminal Electrochemical Impedance Spectroscopy Measurements of Lipid-Laden Atherosclerotic Plaques.

    PubMed

    Packard, René R Sevag; Zhang, XiaoXiao; Luo, Yuan; Ma, Teng; Jen, Nelson; Ma, Jianguo; Demer, Linda L; Zhou, Qifa; Sayre, James W; Li, Rongsong; Tai, Yu-Chong; Hsiai, Tzung K

    2016-09-01

    Four-point electrode systems are commonly used for electric impedance measurements of biomaterials and tissues. We introduce a 2-point system to reduce electrode polarization for heterogeneous measurements of vascular wall. Presence of endoluminal oxidized low density lipoprotein (oxLDL) and lipids alters the electrochemical impedance that can be measured by electrochemical impedance spectroscopy (EIS). We developed a catheter-based 2-point micro-electrode configuration for intravascular deployment in New Zealand White rabbits. An array of 2 flexible round electrodes, 240 µm in diameter and separated by 400 µm was microfabricated and mounted on an inflatable balloon catheter for EIS measurement of the oxLDL-rich lesions developed as a result of high-fat diet-induced hyperlipidemia. Upon balloon inflation, the 2-point electrode array conformed to the arterial wall to allow deep intraplaque penetration via alternating current (AC). The frequency sweep from 10 to 300 kHz generated an increase in capacitance, providing distinct changes in both impedance (Ω) and phase (ϕ) in relation to varying degrees of intraplaque lipid burden in the aorta. Aortic endoluminal EIS measurements were compared with epicardial fat tissue and validated by intravascular ultrasound and immunohistochemistry for plaque lipids and foam cells. Thus, we demonstrate a new approach to quantify endoluminal EIS via a 2-point stretchable electrode strategy. PMID:26857007

  14. Recording long-term potentiation of synaptic transmission by three-dimensional multi-electrode arrays

    PubMed Central

    Kopanitsa, Maksym V; Afinowi, Nurudeen O; Grant, Seth GN

    2006-01-01

    Background Multi-electrode arrays (MEAs) have become popular tools for recording spontaneous and evoked electrical activity of excitable tissues. The majority of previous studies of synaptic transmission in brain slices employed MEAs with planar electrodes that had limited ability to detect signals coming from deeper, healthier layers of the slice. To overcome this limitation, we used three-dimensional (3D) MEAs with tip-shaped electrodes to probe plasticity of field excitatory synaptic potentials (fEPSPs) in the CA1 area of hippocampal slices of 129S5/SvEvBrd and C57BL/6J-TyrC-Brd mice. Results Using 3D MEAs, we were able to record larger fEPSPs compared to signals measured by planar MEAs. Several stimulation protocols were used to induce long-term potentiation (LTP) of synaptic responses in the CA1 area recorded following excitation of Schäffer collateral/commissural fibres. Either two trains of high frequency tetanic stimulation or three trains of theta-burst stimulation caused a persistent, pathway specific enhancement of fEPSPs that remained significantly elevated for at least 60 min. A third LTP induction protocol that comprised 150 pulses delivered at 5 Hz, evoked moderate LTP if excitation strength was increased to 1.5× of the baseline stimulus. In all cases, we observed a clear spatial plasticity gradient with maximum LTP levels detected in proximal apical dendrites of pyramidal neurones. No significant differences in the manifestation of LTP were observed between 129S5/SvEvBrd and C57BL/6J-TyrC-Brd mice with the three protocols used. All forms of plasticity were sensitive to inhibition of N-methyl-D-aspartate (NMDA) receptors. Conclusion Principal features of LTP (magnitude, pathway specificity, NMDA receptor dependence) recorded in the hippocampal slices using MEAs were very similar to those seen in conventional glass electrode experiments. Advantages of using MEAs are the ability to record from different regions of the slice and the ease of conducting

  15. A new high-density (25 electrodes/mm2) penetrating microelectrode array for recording and stimulating sub-millimeter neuroanatomical structures

    NASA Astrophysics Data System (ADS)

    Wark, H. A. C.; Sharma, R.; Mathews, K. S.; Fernandez, E.; Yoo, J.; Christensen, B.; Tresco, P.; Rieth, L.; Solzbacher, F.; Normann, R. A.; Tathireddy, P.

    2013-08-01

    Objective. Among the currently available neural interface devices, there has been a need for a penetrating electrode array with a high electrode-count and high electrode-density (the number of electrodes/mm2) that can be used for electrophysiological studies of sub-millimeter neuroanatomical structures. We have developed such a penetrating microelectrode array with both a high electrode-density (25 electrodes/mm2) and high electrode-count (up to 96 electrodes) for small nervous system structures, based on the existing Utah Slanted Electrode Array (USEA). Such high electrode-density arrays are expected to provide greater access to nerve fibers than the conventionally spaced USEA especially in small diameter nerves. Approach. One concern for such high density microelectrode arrays is that they may cause a nerve crush-type injury upon implantation. We evaluated this possibility during acute (<10 h) in vivo experiments with electrode arrays implanted into small diameter peripheral nerves of anesthetized rats (sciatic nerve) and cats (pudendal nerve). Main results. Successful intrafascicular implantation and viable nerve function was demonstrated via microstimulation, single-unit recordings and histological analysis. Measurements of the electrode impedances and quantified electrode dimensions demonstrated fabrication quality. The results of these experiments show that such high density neural interfaces can be implanted acutely into neural tissue without causing a complete nerve crush injury, while mediating intrafascicular access to fibers in small diameter peripheral nerves. Significance. This new penetrating microelectrode array has characteristics un-matched by other neural interface devices currently available for peripheral nervous system neurophysiological research.

  16. Field shaping arrays: a means to address shading in high field breast MRI

    PubMed Central

    Hancu, Ileana; Lee, Seung-Kyun; Dixon, W. Thomas; Sacolick, Laura; Becerra, Ricardo; Zhang, Zhenghui; McKinnon, Graeme; Alagappan, Vijayanand

    2012-01-01

    Purpose To develop a simple correction approach to mitigate shading in 3T breast MRI. Materials and Methods A slightly modified breast receive (Rx) array, which we termed field shaping array (FSA), was shown to mitigate breast shading at 3T. In this FSA, one Rx element was selectively unblocked and tuned off the Larmor frequency during the transmit (Tx) phase. The current flowing in this element during Tx created a secondary transmit field; the vector addition of this field and the one created directly by the body coil resulted in a more uniform excitation profile over the entire breast area. The receive Rx element was returned to its intended tuning during the Rx phase, ensuring unperturbed signal reception. Results Using the FSA, improved Tx field uniformity better fat suppression, increased image homogeneity and reduced power deposition was seen in all volunteers studied. Conclusion A simple modification of a standard breast Rx array, converting it to a field shaping array, was shown to mitigate breast shading in all volunteers studied. PMID:22730242

  17. Robust myoelectric signal detection based on stochastic resonance using multiple-surface-electrode array made of carbon nanotube composite paper

    NASA Astrophysics Data System (ADS)

    Shirata, Kento; Inden, Yuki; Kasai, Seiya; Oya, Takahide; Hagiwara, Yosuke; Kaeriyama, Shunichi; Nakamura, Hideyuki

    2016-04-01

    We investigated the robust detection of surface electromyogram (EMG) signals based on the stochastic resonance (SR) phenomenon, in which the response to weak signals is optimized by adding noise, combined with multiple surface electrodes. Flexible carbon nanotube composite paper (CNT-cp) was applied to the surface electrode, which showed good performance that is comparable to that of conventional Ag/AgCl electrodes. The SR-based EMG signal system integrating an 8-Schmitt-trigger network and the multiple-CNT-cp-electrode array successfully detected weak EMG signals even when the subject’s body is in the motion, which was difficult to achieve using the conventional technique. The feasibility of the SR-based EMG detection technique was confirmed by demonstrating its applicability to robot hand control.

  18. Biaxially stretchable supercapacitors based on the buckled hybrid fiber electrode array

    NASA Astrophysics Data System (ADS)

    Zhang, Nan; Zhou, Weiya; Zhang, Qiang; Luan, Pingshan; Cai, Le; Yang, Feng; Zhang, Xiao; Fan, Qingxia; Zhou, Wenbin; Xiao, Zhuojian; Gu, Xiaogang; Chen, Huiliang; Li, Kewei; Xiao, Shiqi; Wang, Yanchun; Liu, Huaping; Xie, Sishen

    2015-07-01

    In order to meet the growing need for smart bionic devices and epidermal electronic systems, biaxial stretchability is essential for energy storage units. Based on porous single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) hybrid fiber, we designed and fabricated a biaxially stretchable supercapacitor, which possesses a unique configuration of the parallel buckled hybrid fiber array. Owing to the reticulate SWCNT film and the improved fabrication technique, the hybrid fiber retained its porous architecture both outwardly and inwardly, manifesting a superior capacity of 215 F g-1. H3PO4-polyvinyl alcohol gel with an optimized component ratio was introduced as both binder and stretchable electrolyte, which contributed to the regularity and stability of the buckled fiber array. The buckled structure and the quasi one-dimensional character of the fibers endow the supercapacitor with 100% stretchability along all directions. In addition, the supercapacitor exhibited good transparency, as well as excellent electrochemical properties and stability after being stretched 5000 times.In order to meet the growing need for smart bionic devices and epidermal electronic systems, biaxial stretchability is essential for energy storage units. Based on porous single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) hybrid fiber, we designed and fabricated a biaxially stretchable supercapacitor, which possesses a unique configuration of the parallel buckled hybrid fiber array. Owing to the reticulate SWCNT film and the improved fabrication technique, the hybrid fiber retained its porous architecture both outwardly and inwardly, manifesting a superior capacity of 215 F g-1. H3PO4-polyvinyl alcohol gel with an optimized component ratio was introduced as both binder and stretchable electrolyte, which contributed to the regularity and stability of the buckled fiber array. The buckled structure and the quasi one-dimensional character of the

  19. A new multi-electrode array design for chronic neural recording, with independent and automatic hydraulic positioning.

    PubMed

    Sato, T; Suzuki, T; Mabuchi, K

    2007-02-15

    We report on a new microdrive design, which enables the construction of multi-electrode arrays capable of chronically recording the multi-unit neural activity of waking animals. Our principal motivation for inventing this device was to simplify the task of positioning electrodes, which consumes a considerable amount of time and requires a high level of skill. With the new microdrives, each electrode is independently and automatically driven into place. A hydraulic drive system is adopted to reduce the size, weight, and cost of the structure. The hydraulic fluid is also used as a part of the electrical circuit, and facilitates the wiring of the electrodes. A routing system has been attached to reduce the number of tube connections. The microdrive is cylindrical, has a diameter of 23.5 mm, a height of 37 mm, and a weight of 15 g. It allows for up to 22 electrodes, which are arranged on a 0.35 mm grid. Each electrode can be positioned at any depth up to approximately 4mm. The microdrive was evaluated under acute and chronic recording experiments, and is shown to be capable of automatically positioning each electrode and successfully recording the neural signals of waking rats. PMID:16996616

  20. Barbed channels enhance unidirectional connectivity between neuronal networks cultured on multi electrode arrays

    PubMed Central

    le Feber, Joost; Postma, Wybren; de Weerd, Eddy; Weusthof, Marcel; Rutten, Wim L. C.

    2015-01-01

    Cultured neurons on multi electrode arrays (MEAs) have been widely used to study various aspects of neuronal (network) functioning. A possible drawback of this approach is the lack of structure in these networks. At the single cell level, several solutions have been proposed to enable directed connectivity, and promising results were obtained. At the level of connected sub-populations, a few attempts have been made with promising results. First assessment of the designs' functionality, however, suggested room for further improvement. We designed a two chamber MEA aiming to create a unidirectional connection between the networks in both chambers (“emitting” and “receiving”). To achieve this unidirectionality, all interconnecting channels contained barbs that hindered axon growth in the opposite direction (from receiving to emitting chamber). Visual inspection showed that axons predominantly grew through the channels in the promoted direction. This observation was confirmed by spontaneous activity recordings. Cross-correlation between the signals from two electrodes inside the channels suggested signal propagation at ≈2 m/s from emitting to receiving chamber. Cross-correlation between the firing patterns in both chambers indicated that most correlated activity was initiated in the emitting chamber, which was also reflected by a significantly lower fraction of partial bursts (i.e., a one-chamber-only burst) in the emitting chamber. Finally, electrical stimulation in the emitting chamber induced a fast response in that chamber, and a slower response in the receiving chamber. Stimulation in the receiving chamber evoked a fast response in that chamber, but no response in the emitting chamber. These results confirm the predominantly unidirectional nature of the connecting channels from emitting to receiving chamber. PMID:26578869

  1. Fabrication of nano-electrode arrays of free-standing carbon nanotubes on nano-patterned substrate by imprint method

    NASA Astrophysics Data System (ADS)

    Chang, W. S.; Kim, J. W.; Choi, D. G.; Han, C. S.

    2011-01-01

    The synthesis of isolated carbon nanotubes with uniform outer diameters and ordered spacing over wafer-scale areas was investigated for fabrication of nano-electrode arrays on silicon wafers for field emission and sensor devices. Multi-walled carbon nanotubes (MWCNTs) were grown on TiN electrode layer with iron catalyst patterned by nano-imprint lithography (NIL), which allows the precise placement of individual CNTs on a substrate. The proposed techniques, including plasma-enhanced chemical vapor deposition (PECVD) and NIL, are simple, inexpensive, and reproducible methods for fabrication of nano-scale devices in large areas. The catalyst patterns were defined by an array of circles with 200 nm in diameter, and variable lengths of pitch. The nano-patterned master and Fe catalyst were observed with good pattern fidelity over a large area by atomic force microscope (AFM) and scanning electron microscopy (SEM). Nano-electrodes of MWCNTs had diameters ranging from 50 nm to 100 nm and lengths of about 300 nm. Field emission tests showed the reducing ignition voltage as the geometry of nanotube arrays was controlled by catalyst patterning. These results showed a wafer-scale approach to the control of the size, pitch, and position of nano-electrodes of nanotubes for various applications including electron field-emission sources, electrochemical probes, functionalized sensor elements, and so on.

  2. Investigation of the electroactive capability for the supercapacitor electrode with cobalt oxide rhombus nanopillar and nanobrush arrays

    NASA Astrophysics Data System (ADS)

    Liu, Yu-Bin; Lin, Lu-Yin; Huang, Ying-Yu; Tu, Chao-Chi

    2016-05-01

    Well-defined nanostructures of the cobalt oxide are designed intensively to pursue large surface area and high conductivity as the electroactive material for supercapacitors (SCs). Instead of merely fabricating effective electroactive materials, two kinds of the cobalt oxide nanostructures synthesized directly on nickel foam to achieve good contact between the material and the substrate are compared to clarify the growth mechanism and the structure-dependent SC performance. The nanobrushes are completely composed of nanoparticles while the rhombus nanopillars present integrated structure by the recrystallization of single nanopillars. A higher specific capacitance (CF) of 509 F/g is obtained for the SC electrode with CoO rhombus nanopillar array at a scan rate of 10 mV/s, comparing to that of 169 F/g for the CoO nanobrush array-based SC electrode, due to the larger electroactive surface area and less recombination sites for the former case. The CF value is enhanced by 38% as compared with the initial value after 3000 cycles of repeated charge/discharge process for the CoO rhombus nanopillar array-based SC electrode due to the activation of the material. The results provide a blue print for achieving highly efficient SC electrode by carefully designing the well-established electroactive material to attain facile and long-lasting faradic reactions.

  3. Combining Multiple Electrode Arrays for Two-Dimensional Electrical Resistivity Imaging Using the Unsupervised Classification Technique

    NASA Astrophysics Data System (ADS)

    Ishola, K. S.; Nawawi, M. N. M.; Abdullah, K.

    2015-06-01

    This article describes the use of k-means clustering, an unsupervised image classification technique, to help interpret subsurface targets. The k-means algorithm is employed to combine and classify the two-dimensional (2D) inverse resistivity models obtained from three different electrode arrays. The algorithm is initialized through the selection of the number of clusters, number of iterations and other parameters such as stopping criteria. Automatically, it seeks to find groups of closely related resistivity values that belong to the same cluster and are more similar to each other than resistivity values belonging to other clusters. The approach is applied to both synthetic and field data. The 2D postinversions of the resistivity data were preprocessed by resampling and interpolating to the same coordinate. Following the preprocessing, the three images are combined into a single classified image. All the image preprocessing, manipulation and analysis are performed using the PCI Geomatics software package. The results of the clustering and classification are presented as classified images. An assessment of the performance of the individual and combined images for the synthetic models is carried out using an error matrix, mean absolute error and mean absolute percent error. The estimated errors show that images obtained from maximum values of the reconstructed resistivity for the different models give the best representation of the true models. Additionally, the overall accuracy and kappa values show good agreement between the combined classified images and true models. Depending on the model, the overall accuracy ranges from 86 to 99 %, while the kappa coefficient is in the range of 54-98 %. Classified images with kappa coefficients greater than 0.8 show strong agreement, while images with kappa coefficients greater than 0.5 but less than 0.8 give moderate agreement. For the field data, the k-mean classifier produces images that incorporate structural features of

  4. Opto- μECoG array: a hybrid neural interface with transparent μECoG electrode array and integrated LEDs for optogenetics.

    PubMed

    Kwon, Ki Yong; Sirowatka, Brenton; Weber, Arthur; Li, Wen

    2013-10-01

    Electrocorticogram (ECoG) recordings, taken from electrodes placed on the surface of the cortex, have been successfully implemented for control of brain machine interfaces (BMIs). Optogenetics, direct optical stimulation of neurons in brain tissue genetically modified to express channelrhodopsin-2 (ChR2), enables targeting of specific types of neurons with sub-millisecond temporal precision. In this work, we developed a BMI device, called an Opto- μECoG array, which combines ECoG recording and optogenetics-based stimulation to enable multichannel, bi-directional interactions with neurons. The Opto- μECoG array comprises two sub-arrays, each containing a 4 × 4 distribution of micro-epidural transparent electrodes ( ∼ 200 μm diameter) and embedded light-emitting diodes (LEDs) for optical neural stimulation on a 2.5 × 2.5 mm² footprint to match the bilateral hemispherical area of the visual cortex in a rat. The transparent electrodes were fabricated with indium tin oxide (ITO). Parylene-C served as the main structural and packaging material for flexibility and biocompatibility. Optical, electrical, and thermal characteristics of the fabricated device were investigated and in vivo experiments were performed to evaluate the efficacy of the device. PMID:24144668

  5. Method of interpreting impedance distribution of an earth formation obtained by a moving array using end emitting current electrodes sequentially activated and a series of potential electrodes

    SciTech Connect

    Chapman, C.W.; Angehrn, J.A.

    1987-06-30

    Method of synthesizing the true response characteristics of a combination of different hole-centered electric logging tools in a variety of difficult borehole conditions as provided by (1) determining impedance values of an earth formation penetrated by a borehole filled with a drilling mud of resistivity (Rm), and (2) selectively manipulating the impedance values as impedance entries of a matrix so as to synthesize operations of different hole-centered tools over an associated depth increment with surprising accuracy. Each of the impedance matrices is associated with a matrix gather indexed to one of series of finite, overlapping depth scan increments of the formation measured along the borehole. Each scan increment is dependent on the array length L of the electrode array to define shallow and deep depth markers as well as being centrally indexed to the depth in the borehole of a mid-central electrode assembly of the array at the time of data collection. This provides a true indication of the formation resistivity (Rt) even though the formation is interspaced from the borehole by an invaded zone of resistivity (Rxo) of unknown lateral extend due to drilling mud filtrate invasion.

  6. Evaluation of micro Electroretinograms Recorded with Multiple Electrode Array to Assess Focal Retinal Function

    PubMed Central

    Fujii, Momo; Sunagawa, Genshiro A.; Kondo, Mineo; Takahashi, Masayo; Mandai, Michiko

    2016-01-01

    Full-field electroretinograms (ERGs) are used to objectively assess the mass function of the retina, whereas focal ERGs are used to evaluate the focal retinal function. The purpose of this study was to determine the usefulness of a multiple electrode array (MEA) system for recording ex vivo micro ERGs (mERGs) together with multiunit spike responses of the retinal ganglion cells (RGCs) to assess focal retinal function in isolated mouse retinas. The a- and b-waves of the full-field ERGs were present in the mERG. The b-wave was blocked by L-AP4, an inhibitor of the mGluR6 receptor, and the OFF-component was blocked by exposure to PDA, an antagonist of ionotropic glutamate receptors, with a corresponding RGC responses. mERGs were also recorded from mice with progressive retinal degeneration, the C57BL/6J-Pde6brd1-2J/J (rd1) mice, from which conventional full-field ERGs are non-recordable. A blockade of the glutamate receptors indicated that the negative wave of rd1 mice do not originate from the photoreceptors but from the second or third order neurons. This technique of recording mERGs will be useful in assessing the focal properties of the retinas obtained from eyes with pathology and also to follow the recovery of the physiology of the retina in regenerative studies. PMID:27480484

  7. THE 4-AMINOPYRIDINE IN VITRO EPILEPSY MODEL ANALYZED WITH A PERFORATED MULTI-ELECTRODE ARRAY

    PubMed Central

    Gonzalez-Sulser, Alfredo; Wang, Jing; Motamedi, Gholam K.; Avoli, Massimo; Vicini, Stefano; Dzakpasu, Rhonda

    2010-01-01

    Epileptiform discharges recorded in the 4-aminopyridine (4-AP) in vitro epilepsy model are mediated by glutamatergic and GABAergic signaling. Using a 60-channel perforated multi-electrode array (pMEA) on corticohippocampal slices from 2 to 3 week old mice we recorded interictal- and ictal-like events. When glutamatergic transmission was blocked, interictal-like events events no longer initiated in the hilus or CA3/CA1 pyramidal layers but originated from the dentate gyrus granule and molecular layers. Furthermore, frequencies of interictal-like events were reduced and durations were increased in these regions while cortical discharges were completely blocked. Following GABAA receptor blockade interictal-like events no longer propagated to the dentate gyrus while their frequency in CA3 increased; in addition, ictal-like cortical events became shorter while increasing in frequency. Lastly, drugs that affect tonic and synaptic GABAergic conductance modulate the frequency, duration, initiation and propagation of interictal-like events. These findings confirm and expand on previous studies indicating that multiple synaptic mechanisms contribute to synchronize neuronal network activity in forebrain structures. PMID:20955719

  8. Wirelessly addressable heater array for centrifugal microfluidics and Escherichia coli sterilization.

    PubMed

    Chen, Xing; Song, Lele; Assadsangabi, Babak; Fang, Jie; Mohamed Ali, Mohamed Sultan; Takahata, Kenichi

    2013-01-01

    Localized temperature control and heater interface remain challenges in centrifugal microfluidics and integrated lab-on-a-chip devices. This paper presents a new wireless heating method that enables selective activation of micropatterned resonant heaters using external radiofrequency (RF) fields and its applications. The wireless heaters in an array are individually activated by modulating the frequency of the external field. Temperature of 93 °C is achieved in the heater when resonated with a 0.49-W RF output power. The wireless method is demonstrated to be fully effective for heating samples under spinning at high speeds, showing its applicability to centrifugal systems. Selective sterilization of Escherichia coli through the wireless heating is also demonstrated. Healthcare applications with a focus on wound sterilization are discussed along with preliminary experiments, showing promising results. PMID:24110983

  9. All-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters

    PubMed Central

    Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Plaitano, Marilena; Franchino, Claudio; Gosso, Sara; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2016-01-01

    We report on the ion beam fabrication of all-carbon multi electrode arrays (MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond (SCD) substrates. The fabricated SCD-MEAs are systematically employed for the in vitro simultaneous amperometric detection of the secretory activity from populations of chromaffin cells, demonstrating a new sensing approach with respect to standard techniques. The biochemical stability and biocompatibility of the SCD-based device combined with the parallel recording of multi-electrodes array allow: i) a significant time saving in data collection during drug screening and/or pharmacological tests over a large number of cells, ii) the possibility of comparing altered cell functionality among cell populations, and iii) the repeatition of acquisition runs over many cycles with a fully non-toxic and chemically robust bio-sensitive substrate. PMID:26857940

  10. All-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters.

    PubMed

    Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Plaitano, Marilena; Franchino, Claudio; Gosso, Sara; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2016-01-01

    We report on the ion beam fabrication of all-carbon multi electrode arrays (MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond (SCD) substrates. The fabricated SCD-MEAs are systematically employed for the in vitro simultaneous amperometric detection of the secretory activity from populations of chromaffin cells, demonstrating a new sensing approach with respect to standard techniques. The biochemical stability and biocompatibility of the SCD-based device combined with the parallel recording of multi-electrodes array allow: i) a significant time saving in data collection during drug screening and/or pharmacological tests over a large number of cells, ii) the possibility of comparing altered cell functionality among cell populations, and iii) the repeatition of acquisition runs over many cycles with a fully non-toxic and chemically robust bio-sensitive substrate. PMID:26857940

  11. Numerically controlled atmospheric-pressure plasma sacrificial oxidation using electrode arrays for improving silicon-on-insulator layer uniformity

    NASA Astrophysics Data System (ADS)

    Takei, Hiroyasu; Yoshinaga, Keinosuke; Matsuyama, Satoshi; Yamauchi, Kazuto; Sano, Yasuhisa

    2015-01-01

    Silicon-on-insulator (SOI) wafers are important semiconductor substrates in high-performance devices. In accordance with device miniaturization requirements, ultrathin and highly uniform top silicon layers (SOI layers) are required. A novel method involving numerically controlled (NC) atmospheric-pressure plasma sacrificial oxidation using an electrode array system was developed for the effective fabrication of an ultrathin SOI layer with extremely high uniformity. Spatial resolution and oxidation properties are the key factors controlling ultraprecision machining. The controllability of plasma oxidation and the oxidation properties of the resulting experimental electrode array system were examined. The results demonstrated that the method improved the thickness uniformity of the SOI layer over one-sixth of the area of an 8-in. wafer area.

  12. All-carbon multi-electrode array for real-time in vitro measurements of oxidizable neurotransmitters

    NASA Astrophysics Data System (ADS)

    Picollo, Federico; Battiato, Alfio; Bernardi, Ettore; Plaitano, Marilena; Franchino, Claudio; Gosso, Sara; Pasquarelli, Alberto; Carbone, Emilio; Olivero, Paolo; Carabelli, Valentina

    2016-02-01

    We report on the ion beam fabrication of all-carbon multi electrode arrays (MEAs) based on 16 graphitic micro-channels embedded in single-crystal diamond (SCD) substrates. The fabricated SCD-MEAs are systematically employed for the in vitro simultaneous amperometric detection of the secretory activity from populations of chromaffin cells, demonstrating a new sensing approach with respect to standard techniques. The biochemical stability and biocompatibility of the SCD-based device combined with the parallel recording of multi-electrodes array allow: i) a significant time saving in data collection during drug screening and/or pharmacological tests over a large number of cells, ii) the possibility of comparing altered cell functionality among cell populations, and iii) the repeatition of acquisition runs over many cycles with a fully non-toxic and chemically robust bio-sensitive substrate.

  13. Micro-electrode array recordings reveal reductions in both excitation and inhibition in cultured cortical neuron networks lacking Shank3.

    PubMed

    Lu, C; Chen, Q; Zhou, T; Bozic, D; Fu, Z; Pan, J Q; Feng, G

    2016-02-01

    Numerous risk genes have recently been implicated in susceptibility to autism and schizophrenia. Translating such genetic findings into disease-relevant neurobiological mechanisms is challenging due to the lack of throughput assays that can be used to assess their functions on an appropriate scale. To address this issue, we explored the feasibility of using a micro-electrode array (MEA) as a potentially scalable assay to identify the electrical network phenotypes associated with risk genes. We first characterized local and global network firing in cortical neurons with MEAs, and then developed methods to analyze the alternation between the network active period (NAP) and the network inactive period (NIP), each of which lasts tens of seconds. We then evaluated the electric phenotypes of neurons derived from Shank3 knockout (KO) mice. Cortical neurons cultured on MEAs displayed a rich repertoire of spontaneous firing, and Shank3 deletion led to reduced firing activity. Enhancing excitation with CX546 rescued the deficit in the spike rate in the Shank3 KO network. In addition, the Shank3 KO network produced a shorter NIP, and this altered network firing pattern was normalized by clonazepam, a positive modulator of the GABAA receptor. MEA recordings revealed electric phenotypes that displayed altered excitation and inhibition in the network lacking Shank3. Thus, our study highlights MEAs as an experimental framework for measuring multiple robust neurobiological end points in dynamic networks and as an assay system that could be used to identify electric phenotypes in cultured neuronal networks and to analyze additional risk genes identified in psychiatric genetics. PMID:26598066

  14. Determination of salbutamol in human plasma and urine by high-performance liquid chromatography with a coulometric electrode array system.

    PubMed

    Zhang, X Z; Gan, Y R; Zhao, F N

    2004-01-01

    A method is developed to determine salbutamol in human plasma and urine using high-performance liquid chromatography (HPLC) with a coulometric electrode array system, based on the electrochemical behavior of salbutamol at graphite electrode. The mobile phase component A is 30 mM sodium dihydroxy phosphate-30 mM triethylamine and is adjusted to pH 6.0 with 20% phosphate acid. The mobile phase component B is methanol. The optimized mobile phase composition was A and B in the proportion of 90:10 (v/v). Paracetamol is selected as the external standard. The human plasma and urine samples are pretreated using solid-phase extraction cartridges (Sep-Pak Silica), and the eluting solution is monitored by the coulometric electrode array system. The electrode potentials are set at 300, 400, 550, and 650 mV, respectively. Calibration curves show good linearity, and the recovery of salbutamol proves to be constant and unaffected by the concentration of the drug. This method, developed using HPLC-electrochemical detection, is reproducible and sensitive enough for the determination of salbutamol in human plasma and urine. PMID:15189600

  15. Electrogenerated Chemiluminescence of BODIPY, Ru(bpy)32+, and 9,10-Diphenylanthracene Using Interdigitated Array Electrodes

    SciTech Connect

    Nepomnyashchii, Alexander B.; Kolesov, Grigory; Parkinson, Bruce A.

    2013-07-10

    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 as 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.

  16. Fabrication of matrix-addressable micro-LED arrays based on a novel etch technique

    NASA Astrophysics Data System (ADS)

    Choi, H. W.; Jeon, C. W.; Dawson, M. D.

    2004-08-01

    A novel method of etching which allows the direct interconnection of multiple GaN-based devices is introduced. The mesa structures of devices are etched using an isotropic recipe which produces tapered sidewalls. The extent of inclination can be readily controlled through various etching parameters, which include the ICP power, plate power and pressure, thus modifying the vertical and lateral etch components. This approach has been successfully adopted in the fabrication of interconnect and matrix-addressable micro-LEDs, which offer superior optical and electrical performance and a high degree of uniformity compared to similar devices fabricated using conventional processes.

  17. A highly addressable static droplet array enabling digital control of a single droplet at pico-volume resolution.

    PubMed

    Jeong, Heon-Ho; Lee, Byungjin; Jin, Si Hyung; Jeong, Seong-Geun; Lee, Chang-Soo

    2016-04-26

    Droplet-based microfluidics enabling exquisite liquid-handling has been developed for diagnosis, drug discovery and quantitative biology. Compartmentalization of samples into a large number of tiny droplets is a great approach to perform multiplex assays and to improve reliability and accuracy using a limited volume of samples. Despite significant advances in microfluidic technology, individual droplet handling in pico-volume resolution is still a challenge in obtaining more efficient and varying multiplex assays. We present a highly addressable static droplet array (SDA) enabling individual digital manipulation of a single droplet using a microvalve system. In a conventional single-layer microvalve system, the number of microvalves required is dictated by the number of operation objects; thus, individual trap-and-release on a large-scale 2D array format is highly challenging. By integrating double-layer microvalves, we achieve a "balloon" valve that preserves the pressure-on state under released pressure; this valve can allow the selective releasing and trapping of 7200 multiplexed pico-droplets using only 1 μL of sample without volume loss. This selectivity and addressability completely arranged only single-cell encapsulated droplets from a mixture of droplet compositions via repetitive selective trapping and releasing. Thus, it will be useful for efficient handling of miniscule volumes of rare or clinical samples in multiplex or combinatory assays, and the selective collection of samples. PMID:27075732

  18. Electropolymerization of Uniform Polyaniline Nanorod Arrays on Conducting Oxides as Counter Electrodes in Dye-Sensitized Solar Cells.

    PubMed

    He, Ziming; Liu, Jing; Khoo, Si Yun; Tan, Timothy Thatt Yang

    2016-01-01

    Conventional techniques for the synthesis of oriented polyaniline (PANI) nanostructures are often complex or time consuming. Through an innovative reduced graphene oxide (rGO) modified FTO and a low-potential electropolymerization strategy, the rapid and template-free growth of a highly ordered PANI nanorod array on the FTO substrate is realized. The highly ordered nanostructure of the PANI array leads to a high electrocatalytic activity and chemical stability. The importance of the polymerization potential and rGO surface modification to achieve this nanostructure is revealed. Compared to platinum, the PANI nanorod array exhibits an enhanced performance and stability as counter electrodes in dye-sensitized solar cells, with a 17.6 % enhancement in power conversion efficiency. PMID:26732134

  19. Photoelectrochemical Activity of As-Grown, a-Fe2O3 Nanowire Array Electrodes for Water Splitting

    SciTech Connect

    Chernomordik, B. D.; Russell, H. B.; Cvelbar, U.; Jasinski, J. B.; Kumar, V.; Deutsch, T.; Sunkara, M. K.

    2012-05-17

    Undoped hematite nanowire arrays grown using plasma oxidation of iron foils show significant photoactivity ({approx}0.38 mA cm{sup -2} at 1.5 V versus reversible hydrogen electrode in 1 M KOH). In contrast, thermally oxidized nanowire arrays grown on iron exhibit no photoactivity due to the formation of a thick (>7 {micro}m Fe{sub 1-x}O) interfacial layer. An atmospheric plasma oxidation process required only a few minutes to synthesize hematite nanowire arrays with a 1-5 {micro}m interfacial layer of magnetite between the nanowire arrays and the iron substrate. An amorphous oxide surface layer on hematite nanowires, if present, is shown to decrease the resulting photoactivity of as-synthesized, plasma grown nanowire arrays. The photocurrent onset potential is improved after removing the amorphous surface on the nanowires using an acid etch. A two-step method involving high temperature nucleation followed by growth at low temperature is shown to produce a highly dense and uniform coverage of nanowire arrays.

  20. 3D vector flow using a row-column addressed CMUT array

    NASA Astrophysics Data System (ADS)

    Holbek, Simon; Christiansen, Thomas Lehrmann; Engholm, Mathias; Lei, Anders; Stuart, Mathias Bo; Beers, Christopher; Moesner, Lars Nordahl; Bagge, Jan Peter; Thomsen, Erik Vilain; Jensen, Jørgen Arendt

    2016-04-01

    This paper presents an in-house developed 2-D capacitive micromachined ultrasonic transducer (CMUT) applied for 3-D blood flow estimation. The probe breaks with conventional transducers in two ways; first, the ultrasonic pressure field is generated from thousands of small vibrating micromachined cells, and second, elements are accessed by row and/or column indices. The 62+62 2-D row-column addressed prototype CMUT probe was used for vector flow estimation by transmitting focused ultrasound into a flow-rig with a fully developed parabolic flow. The beam-to-flow angle was 90°. The received data was beamformed and processed offline. A transverse oscillation (TO) velocity estimator was used to estimate the 3-D vector flow along a line originating from the center of the transducer. The estimated velocities in the lateral and axial direction were close to zero as expected. In the transverse direction a characteristic parabolic velocity profile was estimated with a peak velocity of 0.48 m/s +/- 0.02 m/s in reference to the expected 0.54 m/s. The results presented are the first 3-D vector flow estimates obtained with a row-column CMUT probe, which demonstrates that the CMUT technology is feasible for 3-D flow estimation.

  1. Metal-organic framework derived hybrid Co3O4-carbon porous nanowire arrays as reversible oxygen evolution electrodes.

    PubMed

    Ma, Tian Yi; Dai, Sheng; Jaroniec, Mietek; Qiao, Shi Zhang

    2014-10-01

    Hybrid porous nanowire arrays composed of strongly interacting Co3O4 and carbon were prepared by a facile carbonization of the metal-organic framework grown on Cu foil. The resulting material, possessing a high surface area of 251 m(2) g(-1) and a large carbon content of 52.1 wt %, can be directly used as the working electrode for oxygen evolution reaction without employing extra substrates or binders. This novel oxygen evolution electrode can smoothly operate in alkaline solutions (e.g., 0.1 and 1.0 M KOH), affording a low onset potential of 1.47 V (vs reversible hydrogen electrode) and a stable current density of 10.0 mA cm(-2) at 1.52 V in 0.1 M KOH solution for at least 30 h, associated with a high Faradaic efficiency of 99.3%. The achieved ultrahigh oxygen evolution activity and strong durability, with superior performance in comparison to the state-of-the-art noble-metal/transition-metal and nonmetal catalysts, originate from the unique nanowire array electrode configuration and in situ carbon incorporation, which lead to the large active surface area, enhanced mass/charge transport capability, easy release of oxygen gas bubbles, and strong structural stability. Furthermore, the hybrid Co3O4-carbon porous nanowire arrays can also efficiently catalyze oxygen reduction reaction, featuring a desirable four-electron pathway for reversible oxygen evolution and reduction, which is potentially useful for rechargeable metal-air batteries, regenerative fuel cells, and other important clean energy devices. PMID:25216300

  2. Supported noble metals on hydrogen-treated TiO2 nanotube arrays as highly ordered electrodes for fuel cells.

    PubMed

    Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Gao, Yuan; Zhao, Yun; Song, Wei; Shao, Zhigang; Yi, Baolian

    2013-04-01

    Hydrogen-treated TiO2 nanotube (H-TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H-TNTs increases by approximately one order of magnitude in comparison to air-treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H-TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H-TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H-TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H-TNT support. The as-prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H-TNT-loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as-prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X-ray photoelectron spectroscopy shows that after the H-TNT-loaded Pt catalysts are annealed in H2 for the second time, the strong metal-support interaction between the H-TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel-cell testing shows that the power density reaches a maximum of 500 mWcm(-2) when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra-low Pt loading, the new electrode generates a specific power density of 2.68 kWg(Pt) (-1) . It is indicated that H-TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports

  3. 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

  4. Re-evaluation of EMG-torque relation in chronic stroke using linear electrode array EMG recordings

    PubMed Central

    Bhadane, Minal; Liu, Jie; Rymer, W. Zev; Zhou, Ping; Li, Sheng

    2016-01-01

    The objective was to re-evaluate the controversial reports of EMG-torque relation between impaired and non-impaired sides using linear electrode array EMG recordings. Ten subjects with chronic stroke performed a series of submaximal isometric elbow flexion tasks. A 20-channel linear array was used to record surface EMG of the biceps brachii muscles from both impaired and non-impaired sides. M-wave recordings for bilateral biceps brachii muscles were also made. Distribution of the slope of the EMG-torque relations for the individual channels showed a quasi-symmetrical “M” shaped pattern. The lowest value corresponded to the innervation zone (IZ) location. The highest value from the slope curve for each side was selected for comparison to minimize the effect of electrode placement and IZ asymmetry. The slope was greater on the impaired side in 4 of 10 subjects. There were a weak correlation between slope ratio and strength ratio and a moderate to high correlation between slope ratio and M-wave ratio between two sides. These findings suggest that the EMG-torque relations are likely mediated and influenced by multiple factors. Our findings emphasize the importance of electrode placement and suggest the primary role of peripheral adaptive changes in the EMG-torque relations in chronic stroke. PMID:27349938

  5. Re-evaluation of EMG-torque relation in chronic stroke using linear electrode array EMG recordings.

    PubMed

    Bhadane, Minal; Liu, Jie; Rymer, W Zev; Zhou, Ping; Li, Sheng

    2016-01-01

    The objective was to re-evaluate the controversial reports of EMG-torque relation between impaired and non-impaired sides using linear electrode array EMG recordings. Ten subjects with chronic stroke performed a series of submaximal isometric elbow flexion tasks. A 20-channel linear array was used to record surface EMG of the biceps brachii muscles from both impaired and non-impaired sides. M-wave recordings for bilateral biceps brachii muscles were also made. Distribution of the slope of the EMG-torque relations for the individual channels showed a quasi-symmetrical "M" shaped pattern. The lowest value corresponded to the innervation zone (IZ) location. The highest value from the slope curve for each side was selected for comparison to minimize the effect of electrode placement and IZ asymmetry. The slope was greater on the impaired side in 4 of 10 subjects. There were a weak correlation between slope ratio and strength ratio and a moderate to high correlation between slope ratio and M-wave ratio between two sides. These findings suggest that the EMG-torque relations are likely mediated and influenced by multiple factors. Our findings emphasize the importance of electrode placement and suggest the primary role of peripheral adaptive changes in the EMG-torque relations in chronic stroke. PMID:27349938

  6. Electrode array-eluted dexamethasone protects against electrode insertion trauma induced hearing and hair cell losses, damage to neural elements, increases in impedance and fibrosis: A dose response study.

    PubMed

    Bas, Esperanza; Bohorquez, Jorge; Goncalves, Stefania; Perez, Enrique; Dinh, Christine T; Garnham, Carolyn; Hessler, Roland; Eshraghi, Adrien A; Van De Water, Thomas R

    2016-07-01

    We evaluated the effects of dexamethasone base (DXMb) containing electrode arrays in a guinea pig model of cochlear implantation to determine if eluted DXMb could protect the cochlea against electrode insertion trauma (EIT)-induced: 1) loss of hair cells; 2) disruption of neural elements; 3) increases in hearing thresholds; 4) increased electrical impedance and 5) fibrosis. A guinea pig model of EIT-induced hearing and hair cell losses was used to test silicone electrode arrays that contained either 10%, 1%, 0.1%, or 0% levels of micronized DXMb. These four types of electrode arrays were implanted into the scala tympani via basal turn cochleostomies and left in place for 3 months. Hearing thresholds were determined by ABR and CAP recordings in response to a series of defined pure tone stimuli (i.e. 16-0.5 kHz). Changes in impedance were measured between the implant electrode and a reference electrode. Hair cell counts and neural element integrity were determined by confocal microscopy analyses of stained organ of Corti whole mounts obtained from 90 day post-implantation animals. Fibrosis was measured in Masson trichrome stained cross-sections through the organ of Corti. The results showed that either 10% or 1.0% DXMb eluting electrode arrays protected; hearing thresholds, hair cells, and neural elements against EIT-induced losses and damage. Electrode arrays with 0.1% DXMb only partial protected against EIT-induced hearing loss and damage to the cochlea. Protection of hearing thresholds and organ of Corti sensory elements by electrode-eluted DXMb was still apparent at 3 months post-EIT. All three concentrations of DXMb in the electrode arrays prevented EIT-induced increases in impedance. EIT-initiated fibrosis was significantly reduced within the implanted cochlea of the two DXMb concentrations tested. In conclusion, DXMb eluting electrodes protected the cochlea against long term increases in hearing thresholds, loss of hair cells, damage to neural elements and

  7. Fabrication of Mesoporous CoS2 Nanotube Arrays as the Counter Electrodes of Dye-Sensitized Solar Cells.

    PubMed

    Tsai, Jung-Che; Hon, Min-Hsiung; Leu, Ing-Chi

    2015-09-01

    Mesoporous cobalt sulfide nanotube arrays on FTO-coated glass were synthesized by combining three simple technologies: the selective etching of ZnO sacrificial templates, mesoporous Co3 O4 formation from cobalt-chelated chitosan, and ion-exchange reaction (IER). The mesoporous Co3 O4 nanotubes composed of the Co3 O4 nanoparticles possess a high surface area and are taken advantage for further removal of templates and IER. The morphologies and crystal structures of the CoS2 nanotube arrays were characterized by SEM, TEM, and XRD analyses. Their electrocatalytic properties were determined by electrochemical analyses including cyclic voltammetry measurements and Tafel polarization. The DSSCs assembled with a CoS2 counter electrode achieved a power conversion efficiency of 6.13 %, which was comparable to that of the DSSC with the Pt counter electrode (6.04 %). This indicates that the mesoporous CoS2 nanotube array can be a low-cost and efficient alternative for the reduction of electrolytes in DSSCs. PMID:26154709

  8. Impedance biosensor based on interdigitated electrode array for detection of E.coli O157:H7 in food products

    NASA Astrophysics Data System (ADS)

    Ghosh Dastider, Shibajyoti; Barizuddin, Syed; Dweik, Majed; Almasri, Mahmoud F.

    2012-05-01

    An impedance biosensor was designed, fabricated and tested for detection of viable Escherichia coli O157:H7 in food samples. This device consists of interdigitated microelectrode array (IDEA) fabricated using thin layer of sputtered gold, embedded under a polydimethylsiloxane (PDMS) microchannel. The array of electrodes is designed to detect viable EColi in different food products. The active surface area of the detection array was modified using goat anti-E.coli polyclonal IgG antibody. Contaminated food samples were tested by infusing the supernatant containing bacteria over the IDEA's, through the microchannel. Antibody-antigen binding on the electrodes results in impedance change. Four serial concentrations of E.coli contaminated food samples (3x102 CFUmL-1 to 3x105 CFUmL-1) were tested. The biosensor successfully detected the E.coli samples, with the lower detection limit being 3x103 CFUmL-1 (up to 3cells/μl). Comparing the test results with an IDEA impedance biosensor without microchannel (published elsewhere) indicates that this biosensor have two order of magnitude times higher sensitivity. The proposed biosensor provides qualitative and quantitative detection, and potentially could be used for detection of other type of bacteria by immobilizing the specific type of antibody.

  9. AlGaInN laser diode bar and array technology for high-power and individual addressable applications

    NASA Astrophysics Data System (ADS)

    Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Boćkowski, M.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Kucharski, R.; Targowski, G.

    2016-04-01

    The AlGaInN material system allows for laser diodes to be fabricated over a very wide range of wavelengths from u.v., ~380nm, to the visible ~530nm, by tuning the indium content of the laser GaInN quantum well, giving rise to new and novel applications for medical, industrial, display and scientific purposes. Ridge waveguide laser diode structures are fabricated to achieve single mode operation with high optical powers of >100mW with high reliability. Low defectivity and highly uniform GaN substrates allow arrays and bars of nitride lasers to be fabricated. We demonstrate the operation of monolithic AlGaInN laser bars with up to 20 emitters giving optical powers up to 4W cw at ~395nm with a common contact configuration. These bars are suitable for optical pumps and novel extended cavity systems. An alternative package configuration for AlGaInN laser arrays allows for each individual laser to be individually addressable allowing complex free-space and/or fibre optic system integration within a very small form-factor.

  10. Reliability of signals from a chronically implanted, silicon-based electrode array in non-human primate primary motor cortex.

    PubMed

    Suner, Selim; Fellows, Matthew R; Vargas-Irwin, Carlos; Nakata, Gordon Kenji; Donoghue, John P

    2005-12-01

    Multiple-electrode arrays are valuable both as a research tool and as a sensor for neuromotor prosthetic devices, which could potentially restore voluntary motion and functional independence to paralyzed humans. Long-term array reliability is an important requirement for these applications. Here, we demonstrate the reliability of a regular array of 100 microelectrodes to obtain neural recordings from primary motor cortex (MI) of monkeys for at least three months and up to 1.5 years. We implanted Bionic (Cyberkinetics, Inc., Foxboro, MA) silicon probe arrays in MI of three Macaque monkeys. Neural signals were recorded during performance of an eight-direction, push-button task. Recording reliability was evaluated for 18, 35, or 51 sessions distributed over 83, 179, and 569 days after implantation, respectively, using qualitative and quantitative measures. A four-point signal quality scale was defined based on the waveform amplitude relative to noise. A single observer applied this scale to score signal quality for each electrode. A mean of 120 (+/- 17.6 SD), 146 (+/- 7.3), and 119 (+/- 16.9) neural-like waveforms were observed from 65-85 electrodes across subjects for all recording sessions of which over 80% were of high quality. Quantitative measures demonstrated that waveforms had signal-to-noise ratio (SNR) up to 20 with maximum peak-to-peak amplitude of over 1200 microv with a mean SNR of 4.8 for signals ranked as high quality. Mean signal quality did not change over the duration of the evaluation period (slope 0.001, 0.0068 and 0.03; NS). By contrast, neural waveform shape varied between, but not within days in all animals, suggesting a shifting population of recorded neurons over time. Arm-movement related modulation was common and 66% of all recorded neurons were tuned to reach direction. The ability for the array to record neural signals from parietal cortex was also established. These results demonstrate that neural recordings that can provide movement