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Sample records for voltage measurement electrodes

  1. Photoconductivity of high voltage space insulating materials: Measurements with metal electrodes

    NASA Technical Reports Server (NTRS)

    Coffey, H. T.; Nanevicz, J. E.

    1975-01-01

    The electrical conductivities of high voltage insulating materials were measured in the dark and under various intensities of illumination. The materials investigated included FEP Teflon, Kapton-H, fused quartz, and parylene. Conductivities were determined as functions of temperature between 22 and 100 C and light intensity between 0 and 2.5 kW/m2. The thickness dependence of the conductivity was determined for Teflon and Kapton, and the influence of spectral wavelengths on the conductivity was determined in several cases. All measurements were made in a vacuum to simulate a space environment, and all samples had metallic electrodes. The conductivity of Kapton was permanently increased by exposure to light; changes as great as five orders of magnitude were observed after six hours of illumination.

  2. Fluctuations in Xenopus oocytes protein phosphorylation levels during two-electrode voltage clamp measurements.

    PubMed

    Cohen, Asi; Zilberberg, Noam

    2006-05-15

    The biophysical and pharmacological properties of ion channels and transporters are often studied in exogenous expression systems using either the two-electrode voltage clamp (TEVC) in Xenopus oocytes or the patch clamp techniques. Cells machinery is trusted to produce active proteins that are correctly phosphorylated and glycosylated. However, native physiological cellular processes that might be altered during the course of the experiment are often ignored. Here, we detected and quantified the effects of various electrophysiological recording conditions on the phosphorylation levels of Xenopus oocytes proteins, including membrane proteins, as phosphorylation/dephosphorylation events modulate ion channels gating and cell surface expression. Two strategies were chosen to determine relative protein phosphorylation levels: a direct detection with a phospho-Ser/Thr PKA substrate antibody, and a functional method employing two different leak potassium channels as indicators, chosen based on their opposite responses to protein kinase phosphorylation. We report that holding potential, and bath solution properties such as pH, osmolarity, temperature and ion composition, dramatically affect protein phosphorylation levels in Xenopus oocytes. Our results might explain some of the fluctuations in the biophysical properties of expressed channels, often observed during electrophysiological measurements. Minimizing possible misinterpretations could be achieved using either mutated, kinase insensitive, channels or kinases/phosphatases modulators. PMID:16293314

  3. Intracellular calcium measured with calcium-sensitive micro-electrodes and Arsenazo III in voltage-clamped Aplysia neurones.

    PubMed Central

    Gorman, A L; Levy, S; Nasi, E; Tillotson, D

    1984-01-01

    Selected neurones of the abdominal ganglion of Aplysia californica were voltage clamped, injected with the Ca2+-indicator dye Arsenazo III, and impaled with Ca2+-selective micro-electrodes. Measurements of the absorbance signal (Arsenazo III) and Ca2+ micro-electrode potential during and following voltage-dependent Ca2+ influx (induced by voltage-clamp pulses) were simultaneously recorded. In neurones held at -50 mV, the mean intracellular free Ca2+ concentration [( Ca]i) measured by the Ca2+ micro-electrode was 0.18 microM, S.D. = 0.22 microM, n = 13. Bathing the cell in 0 Ca2+ artificial sea water (ASW) or intracellularly injecting EGTA decreased the resting [Ca]i. Voltage-clamp pulses, which maximally activated Ca2+ channels (from -50 to +30 mV), transiently increased both the Arsenazo III absorbance and the Ca2+ micro-electrode signals, indicating a rise in [Ca]i. Given the Ca2+ micro-electrode's limited band width, the peak of the Ca2+ signal during the pulse train could not be resolved; however, there was a net deflexion of this signal following the last pulse which slowly decayed to base line. Bathing the cells in 0 Ca2+ ASW, or reducing the driving force for Ca2+ entry (by stepping the voltage-clamp pulses to much higher membrane potentials) dramatically reduced both the absorbance and the Ca2+ micro-electrode signal increases. On the other hand, bathing the cells in 100 mM-Ca2+ ASW increased both signals. The intracellular Ca2+ gradient within the cytoplasm following voltage-clamp pulses was investigated by moving the Ca2+-selective micro-electrode tip in a step-wise manner relative to the membrane surface. The measured rise in [Ca]i was greatest near the membrane and not measurable within 40-50 microns of the membrane surface. The amplitude of the [Ca]i rise at different distances from the membrane could be fitted by a model based on a simple diffusion of Ca2+ from a plane source. PMID:6434727

  4. Measurement of Radiated Electromagnetic Field due to Low Voltage ESD with Spherical Electrode in 1-3GHz Frequency Bandwidth

    NASA Astrophysics Data System (ADS)

    Kawamata, Ken; Minegishi, Shigeki; Fujiwara, Osamu

    The micro-gap discharge as the low voltage ESD shows very fast transition-duration of about 32 ps or less. Furthermore, the breakdown field strength in the gap was very high of about 80 MV/m in low voltage discharging of below 400V. The relationship between the breakdown field strength in the gap and the amplitude of radiated electromagnetic field was examined in experimental study. The amplitude of radiated electromagnetic field was proportion to the breakdown field strength at the gap in the resonance experimental system using the discharge electrode with dipole configuration. In this time, we present an improved experimental system to measure the amplitude of radiated electromagnetic filed in more wideband region using spherical electrodes and a horn antenna. As a result, the amplitude of radiated electromagnetic field is proportion to the discharge voltage from 300V to 620V, and the amplitude of radiated electromagnetic field was according to the diameter of spherical electrode in 1-3GHz frequency bandwidth.

  5. Current-voltage characteristics of single-molecule diarylethene junctions measured with adjustable gold electrodes in solution.

    PubMed

    Briechle, Bernd M; Kim, Youngsang; Ehrenreich, Philipp; Erbe, Artur; Sysoiev, Dmytro; Huhn, Thomas; Groth, Ulrich; Scheer, Elke

    2012-01-01

    We report on an experimental analysis of the charge transport through sulfur-free photochromic molecular junctions. The conductance of individual molecules contacted with gold electrodes and the current-voltage characteristics of these junctions are measured in a mechanically controlled break-junction system at room temperature and in liquid environment. We compare the transport properties of a series of molecules, labeled TSC, MN, and 4Py, with the same switching core but varying side-arms and end-groups designed for providing the mechanical and electrical contact to the gold electrodes. We perform a detailed analysis of the transport properties of TSC in its open and closed states. We find rather broad distributions of conductance values in both states. The analysis, based on the assumption that the current is carried by a single dominating molecular orbital, reveals distinct differences between both states. We discuss the appearance of diode-like behavior for the particular species 4Py that features end-groups, which preferentially couple to the metal electrode by physisorption. We show that the energetic position of the molecular orbital varies as a function of the transmission. Finally, we show for the species MN that the use of two cyano end-groups on each side considerably enhances the coupling strength compared to the typical behavior of a single cyano group. PMID:23365792

  6. Determining resistivity of a formation adjacent to a borehole having casing by generating constant current flow in portion of casing and using at least two voltage measurement electrodes

    DOEpatents

    Vail, III, William Banning (Bothell, WA)

    2000-01-01

    Methods of operation of different types of multiple electrode apparatus vertically disposed in a cased well to measure information related to the resistivity of adjacent geological formations from within the cased well are described. The multiple electrode apparatus has a minimum of two spaced apart voltage measurement electrodes that electrically engage a first portion of the interior of the cased well and that provide at least first voltage information. Current control means are used to control the magnitude of any selected current that flows along a second portion of the interior of the casing to be equal to a predetermined selected constant. The first portion of the interior of the cased well is spaced apart from the second portion of the interior of the cased well. The first voltage information and the predetermined selected constant value of any selected current flowing along the casing are used in part to determine a magnitude related to the formation resistivity adjacent to the first portion of the interior of the cased well. Methods and apparatus having a plurality of voltage measurement electrodes are disclosed that provide voltage related information in the presence of constant currents flowing along the casing which is used to provide formation resistivity.

  7. Calculation and measurement of a neutral air flow velocity impacting a high voltage capacitor with asymmetrical electrodes

    SciTech Connect

    Malík, M. Primas, J.; Kopecký, V.; Svoboda, M.

    2014-01-15

    This paper deals with the effects surrounding phenomenon of a mechanical force generated on a high voltage asymmetrical capacitor (the so called Biefeld-Brown effect). A method to measure this force is described and a formula to calculate its value is also given. Based on this the authors derive a formula characterising the neutral air flow velocity impacting an asymmetrical capacitor connected to high voltage. This air flow under normal circumstances lessens the generated force. In the following part this velocity is measured using Particle Image Velocimetry measuring technique and the results of the theoretically calculated velocity and the experimentally measured value are compared. The authors found a good agreement between the results of both approaches.

  8. Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator.

    PubMed

    Hao, Zhibin; Wang, Guozhu; Li, Wenbin; Zhang, Junguo; Kan, Jiangming

    2015-01-01

    The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended. PMID:26302491

  9. Effects of Electrode Material on the Voltage of a Tree-Based Energy Generator

    PubMed Central

    2015-01-01

    The voltage between a standing tree and its surrounding soil is regarded as an innovative renewable energy source. This source is expected to provide a new power generation system for the low-power electrical equipment used in forestry. However, the voltage is weak, which has caused great difficulty in application. Consequently, the development of a method to increase the voltage is a key issue that must be addressed in this area of applied research. As the front-end component for energy harvesting, a metal electrode has a material effect on the level and stability of the voltage obtained. This study aimed to preliminarily ascertain the rules and mechanisms that underlie the effects of electrode material on voltage. Electrodes of different materials were used to measure the tree-source voltage, and the data were employed in a comparative analysis. The results indicate that the conductivity of the metal electrode significantly affects the contact resistance of the electrode-soil and electrode-trunk contact surfaces, thereby influencing the voltage level. The metal reactivity of the electrode has no significant effect on the voltage. However, passivation of the electrode materials markedly reduces the voltage. Suitable electrode materials are demonstrated and recommended. PMID:26302491

  10. Feedback control of electrode offset voltage during functional electrical stimulation.

    PubMed

    Chu, Jun-Uk; Song, Kang-Il; Shon, Ahnsei; Han, Sungmin; Lee, Soo Hyun; Kang, Ji Yoon; Hwang, Dosik; Suh, Jun-Kyo Francis; Choi, Kuiwon; Youn, Inchan

    2013-08-15

    Control of the electrode offset voltage is an important issue related to the processes of functional electrical stimulation because excess charge accumulation over time damages both the tissue and the electrodes. This paper proposes a new feedback control scheme to regulate the electrode offset voltage to a predetermined reference value. The electrode offset voltage was continuously monitored using a sample-and-hold (S/H) circuit during stimulation and non-stimulation periods. The stimulation current was subsequently adjusted using a proportional-integral (PI) controller to minimise the error between the reference value and the electrode offset voltage. During the stimulation period, the electrode offset voltage was maintained through the S/H circuit, and the PI controller did not affect the amplitude of the stimulation current. In contrast, during the non-stimulation period, the electrode offset voltage was sampled through the S/H circuit and rapidly regulated through the PI controller. The experimental results obtained using a nerve cuff electrode showed that the electrode offset voltage was successfully controlled in terms of the performance specifications, such as the steady- and transient-state responses and the constraint of the controller output. Therefore, the proposed control scheme can potentially be used in various nerve stimulation devices and applications requiring control of the electrode offset voltage. PMID:23685268

  11. Methods for testing high voltage connectors in vacuum, measurements of thermal stresses in encapsulated assemblies, and measurement of dielectric strength of electrodes in encapsulants versus radius of curvature

    NASA Technical Reports Server (NTRS)

    Bever, R. S.

    1976-01-01

    Internal embedment stress measurements were performed, using tiny ferrite core transformers, whose voltage output was calibrated versus pressure by the manufacturer. Comparative internal strain measurements were made by attaching conventional strain gages to the same type of resistors and encapsulating these in various potting compounds. Both types of determinations were carried out while temperature cycling from 77 C to -50 C.

  12. Arc voltage distribution skewness as an indicator of electrode gap during vacuum arc remelting

    DOEpatents

    Williamson, Rodney L. (Albuquerque, NM); Zanner, Frank J. (Sandia Park, NM); Grose, Stephen M. (Glenwood, WV)

    1998-01-01

    The electrode gap of a VAR is monitored by determining the skewness of a distribution of gap voltage measurements. A decrease in skewness indicates an increase in gap and may be used to control the gap.

  13. Arc voltage distribution skewness as an indicator of electrode gap during vacuum arc remelting

    DOEpatents

    Williamson, R.L.; Zanner, F.J.; Grose, S.M.

    1998-01-13

    The electrode gap of a VAR is monitored by determining the skewness of a distribution of gap voltage measurements. A decrease in skewness indicates an increase in gap and may be used to control the gap. 4 figs.

  14. Evaluation of Niobium as Candidate Electrode Material for DC High Voltage Photoelectron Guns

    NASA Technical Reports Server (NTRS)

    BastaniNejad, M.; Mohamed, Abdullah; Elmustafa, A. A.; Adderley, P.; Clark, J.; Covert, S.; Hansknecht, J.; Hernandez-Garcia, C.; Poelker, M.; Mammei, R.; Surles-Law, K.; Williams, P.

    2012-01-01

    The field emission characteristics of niobium electrodes were compared to those of stainless steel electrodes using a DC high voltage field emission test apparatus. A total of eight electrodes were evaluated: two 304 stainless steel electrodes polished to mirror-like finish with diamond grit and six niobium electrodes (two single-crystal, two large-grain, and two fine-grain) that were chemically polished using a buffered-chemical acid solution. Upon the first application of high voltage, the best large-grain and single-crystal niobium electrodes performed better than the best stainless steel electrodes, exhibiting less field emission at comparable voltage and field strength. In all cases, field emission from electrodes (stainless steel and/or niobium) could be significantly reduced and sometimes completely eliminated, by introducing krypton gas into the vacuum chamber while the electrode was biased at high voltage. Of all the electrodes tested, a large-grain niobium electrode performed the best, exhibiting no measurable field emission (< 10 pA) at 225 kV with 20 mm cathode/anode gap, corresponding to a field strength of 18:7 MV/m.

  15. Measuring electrode assembly

    DOEpatents

    Bordenick, J.E.

    1988-04-26

    A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture. 2 figs.

  16. Measuring electrode assembly

    DOEpatents

    Bordenick, John E. (West Mifflin, PA)

    1989-01-01

    A pH measuring electrode assembly for immersion in a solution includes an enclosed cylindrical member having an aperture at a lower end thereof. An electrolyte is located in the cylindrical member above the level of the aperture and an electrode is disposed in this electrolyte. A ring formed of an ion porous material is mounted relative to the cylindrical member so that a portion of this ring is rotatable relative to and is covering the aperture in the cylindrical member. A suitable mechanism is also provided for indicating which one of a plurality of portions of the ring is covering the aperture and to keep track of which portions of the ring have already been used and become clogged. Preferably, the electrode assembly also includes a glass electrode member in the center thereof including a second electrolyte and electrode disposed therein. The cylindrical member is resiliently mounted relative to the glass electrode member to provide for easy rotation of the cylindrical member relative to the glass electrode member for changing of the portion of the ring covering the aperture.

  17. Application of active electrode compensation to perform continuous voltage-clamp recordings with sharp microelectrodes

    NASA Astrophysics Data System (ADS)

    Gómez-González, J. F.; Destexhe, A.; Bal, T.

    2014-10-01

    Objective. Electrophysiological recordings of single neurons in brain tissues are very common in neuroscience. Glass microelectrodes filled with an electrolyte are used to impale the cell membrane in order to record the membrane potential or to inject current. Their high resistance induces a high voltage drop when passing current and it is essential to correct the voltage measurements. In particular, for voltage clamping, the traditional alternatives are two-electrode voltage-clamp technique or discontinuous single electrode voltage-clamp (dSEVC). Nevertheless, it is generally difficult to impale two electrodes in a same neuron and the switching frequency is limited to low frequencies in the case of dSEVC. We present a novel fully computer-implemented alternative to perform continuous voltage-clamp recordings with a single sharp-electrode. Approach. To reach such voltage-clamp recordings, we combine an active electrode compensation algorithm (AEC) with a digital controller (AECVC). Main results. We applied two types of control-systems: a linear controller (proportional plus integrative controller) and a model-based controller (optimal control). We compared the performance of the two methods to dSEVC using a dynamic model cell and experiments in brain slices. Significance. The AECVC method provides an entirely digital method to perform continuous recording and smooth switching between voltage-clamp, current clamp or dynamic-clamp configurations without introducing artifacts.

  18. High-voltage electrode optimization towards uniform surface treatment by a pulsed volume discharge

    NASA Astrophysics Data System (ADS)

    Ponomarev, A. V.; Pedos, M. S.; Scherbinin, S. V.; Mamontov, Y. I.; Ponomarev, S. V.

    2015-11-01

    In this study, the shape and material of the high-voltage electrode of an atmospheric pressure plasma generation system were optimised. The research was performed with the goal of achieving maximum uniformity of plasma treatment of the surface of the low-voltage electrode with a diameter of 100 mm. In order to generate low-temperature plasma with the volume of roughly 1 cubic decimetre, a pulsed volume discharge was used initiated with a corona discharge. The uniformity of the plasma in the region of the low-voltage electrode was assessed using a system for measuring the distribution of discharge current density. The system's low-voltage electrode - collector - was a disc of 100 mm in diameter, the conducting surface of which was divided into 64 radially located segments of equal surface area. The current at each segment was registered by a high-speed measuring system controlled by an ARM™-based 32-bit microcontroller. To facilitate the interpretation of results obtained, a computer program was developed to visualise the results. The program provides a 3D image of the current density distribution on the surface of the low-voltage electrode. Based on the results obtained an optimum shape for a high-voltage electrode was determined. Uniformity of the distribution of discharge current density in relation to distance between electrodes was studied. It was proven that the level of non-uniformity of current density distribution depends on the size of the gap between electrodes. Experiments indicated that it is advantageous to use graphite felt VGN-6 (Russian abbreviation) as the material of the high-voltage electrode's emitting surface.

  19. The effect of electrode temperature on the sparking voltage of short spark gaps

    NASA Technical Reports Server (NTRS)

    Silsbee, F B

    1924-01-01

    This report presents the results of an investigation to determine what effect the temperature of spark plug electrodes might have on the voltage at which a spark occurred. A spark gap was set up so that one electrode could be heated to temperatures up to 700 degrees C., while the other electrode and the air in the gap were maintained at room temperature. The sparking voltages were measured both with direct voltage and with voltage impulse from ignition coil. It was found that the sparking voltage of the gap decreased materially with increase of temperature. This change was more marked when the hot electrode was of negative polarity. The phenomena observed can be explained by the ionic theory of gaseous conduction, and serve to account for certain hitherto unexplained actions in the operation of internal combustion engines. These results indicate that the ignition spark will pass more readily when the spark-plug design is such as to make the electrodes run hot. This possible gain is, however, very closely limited by the danger of producing preignition. These experiments also show that sparking is somewhat easier when the hot electrode (which is almost always the central electrode) is negative than when the polarity is reversed.

  20. Cell voltage versus electrode potential range in aqueous supercapacitors

    NASA Astrophysics Data System (ADS)

    Dai, Zengxin; Peng, Chuang; Chae, Jung Hoon; Ng, Kok Chiang; Chen, George Z.

    2015-04-01

    Supercapacitors with aqueous electrolytes and nanostructured composite electrodes are attractive because of their high charging-discharging speed, long cycle life, low environmental impact and wide commercial affordability. However, the energy capacity of aqueous supercapacitors is limited by the electrochemical window of water. In this paper, a recently reported engineering strategy is further developed and demonstrated to correlate the maximum charging voltage of a supercapacitor with the capacitive potential ranges and the capacitance ratio of the two electrodes. Beyond the maximum charging voltage, a supercapacitor may still operate, but at the expense of a reduced cycle life. In addition, it is shown that the supercapacitor performance is strongly affected by the initial and zero charge potentials of the electrodes. Further, the differences are highlighted and elaborated between freshly prepared, aged under open circuit conditions, and cycled electrodes of composites of conducting polymers and carbon nanotubes. The first voltammetric charging-discharging cycle has an electrode conditioning effect to change the electrodes from their initial potentials to the potential of zero voltage, and reduce the irreversibility.

  1. Wideband bio-impedance spectroscopy using voltage source and tetra-polar electrode configuration

    NASA Astrophysics Data System (ADS)

    Yoo, Pil Joong; Lee, Dae Hyun; In Oh, Tong; Woo, Eung Je

    2010-04-01

    Most bio-impedance spectroscopy (BIS) systems inject sinusoidal current with a variable frequency into a sample with a known geometry through a pair of electrodes. Adopting the so-called tetra-polar configuration, it measures induced voltage data on a separate pair of electrodes. Impedance spectra are plotted in a certain range of frequency. We found that its accuracy decreases at high frequencies primarily due to the deteriorated performance of the constant current source at high frequencies. Using a previous BIS system we developed, we found that the overall performance can be kept high up to several hundred kHz. In this study, we propose a design of a wideband BIS system using a constant voltage source. It is based on the simple voltage division between an internal resistor and an external sample or load. We switch the value of the internal resistor (Rs) so that the source voltage is divided more or less equally. Two pairs of electrodes are attached to the sample. Two independent voltmeters are used to separately measure two voltages across the chosen internal resistor and the sample. The voltage measurement across the sample is done between the second electrode pair only. This enables us to adopt the tetra-polar configuration to avoid the problem related with contact impedances. We describe the design, construction and performance of the new BIS system with 468 Hz to 2.2 MHz bandwidth. We will compare the results with those using the impedance analyzer.

  2. Improving membrane voltage measurements

    E-print Network

    Cai, Long

    as fluorescence resonance energy transfer (FRET) donor and acceptor to develop a voltage sensor, named Mermaid of Aequorea victoria green fluorescent protein (GFP) emitting blue, cyan and yellow and the discovery of GFP have been developed for fluorescence resonance energy transfer (FRET) applications2. Unimolecular

  3. Electrode Response in Seismo-Electric Measurements

    NASA Astrophysics Data System (ADS)

    Dietrich, M.; Devi, M. S.; Cougoulat, G.; Garambois, S.

    2014-12-01

    Seismo-electric measurements consist in recording the transient electric fields generated by seismic waves propagating in fluid-filled porous or fractured media. These electric fields are usually measured by voltage differences between two electrodes. Unfortunately, the electrode spacing and their locations on the ground surface have a direct influence on the signal-to-noise ratio of the measurements, on the recorded waveforms and on their arrival times. Using a filter theory approach and full waveform numerical simulations of the coupled seismic and electromagnetic (EM) wave propagation in porous media, we show that the co-seismic electric arrivals and the small-amplitude EM interface response can be severely distorted and/or attenuated by conventional surface electrode layouts. To this end, we have computed synthetic electrograms providing the electric potential, to allow us to determine voltage differences between two arbitrary locations of electrodes. Unlike the low-pass filter obtained by connecting two geophones in series, the filter associated with a voltage difference is shown to be a band-pass filter. As a result, not only horizontally and obliquely propagating waves but also vertically propagating waves undergo selective frequency attenuation in the 0-150 Hz frequency band used in field measurements. It also turns out that electrode spacing cannot be optimized to enhance the electric signature of typical seismic reflections and EM interface response, neither with horizontal dipoles nor with reasonably sized vertical dipoles. To circumvent this problem, we consider arrangements of 3 and 5 electrodes analogous to multilayer capacitors in electronics. We show that such arrangements are ideally described by low-pass filters preserving the quasi-plane waves corresponding to the EM interface response. However, in reality, these benefits are challenged by the imperfect coupling between the electrodes and the ground, represented by an electrode contact resistance which is possibly frequency-dependent and complex. Somewhat paradoxically, poorly grounded electrodes can in some cases improve the measurement of the electric field. This suggests that electrode contact resistance should be measured whenever possible to be accounted for in the dipole or multi-electrode electric response.

  4. Design and Testing of 100 mK High-voltage Electrodes for AEgIS

    NASA Astrophysics Data System (ADS)

    Derking, J. H.; Liberadzka, J.; Koettig, T.; Bremer, J.

    The AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) experiment at CERN has as main goal to perform the first direct measurement of the Earth's gravitational acceleration on antihydrogen atoms within 1% precision. To reach this precision, the antihydrogen should be cooled down to about 100 mK to reduce its random vertical velocity. This is obtained by mounting a Penning trap consisting of multiple high-voltage electrodes on the mixing chamber of a dilution refrigerator with cooling capacity of 100 ?W at 50 mK. A design of the high-voltage electrodes is made and experimentally tested at operating conditions. The high-voltage electrodes are made of sapphire with four gold sputtered electrode sectors on it. The electrodes have a width of 40 mm, a height of 18 mm and a thickness of 5.8 mm and for performance testing are mountedto the mixing chamber of a dilution refrigerator with a 250 ?m thick indium foil sandwiched inbetween the two to increase the thermal contact. A static heat load of 120 nW applied to the top surface of the electrode results in a maximum measured temperature of 100 mK while the mixing chamber is kept at a constant temperature of 50 mK. The measured totalthermal resistivity lies in the range of 210-260 cm2 K4 W-1, which is much higher than expected from literature. Further research needs to be done to investigate this.

  5. TiN coated aluminum electrodes for DC high voltage electron guns

    DOE PAGESBeta

    Mamun, Md Abdullah A.; Elmustafa, Abdelmageed A.; Taus, Rhys; Forman, Eric; Poelker, Matthew

    2015-05-01

    Preparing electrodes made of metals like stainless steel, for use inside DC high voltage electron guns, is a labor-intensive and time-consuming process. In this paper, the authors report the exceptional high voltage performance of aluminum electrodes coated with hard titanium nitride (TiN). The aluminum electrodes were comparatively easy to manufacture and required only hours of mechanical polishing using silicon carbide paper, prior to coating with TiN by a commercial vendor. The high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, was compared to that of bare aluminum electrodes, and electrodes manufactured from titanium alloymore »(Ti-6AI-4V). Following gas conditioning, each TiN-coated aluminum electrode reached -225 kV bias voltage while generating less than 100 pA of field emission (« less

  6. Field Emission Measurements from Niobium Electrodes

    SciTech Connect

    M. BastaniNejad, P.A. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, R. Mammei, M. Poelker

    2011-03-01

    Increasing the operating voltage of a DC high voltage photogun serves to minimize space charge induced emittance growth and thereby preserve electron beam brightness, however, field emission from the photogun cathode electrode can pose significant problems: constant low level field emission degrades vacuum via electron stimulated desorption which in turn reduces photocathode yield through chemical poisoning and/or ion bombardment and high levels of field emission can damage the ceramic insulator. Niobium electrodes (single crystal, large grain and fine grain) were characterized using a DC high voltage field emission test stand at maximum voltage -225kV and electric field gradient > 10MV/m. Niobium electrodes appear to be superior to diamond-paste polished stainless steel electrodes.

  7. Senderovich 1 Electrode Design Adjustments to a High Voltage Electron Gun

    E-print Network

    Hoffstaetter, Georg

    Senderovich 1 Electrode Design Adjustments to a High Voltage Electron Gun Igor Senderovich Abstract, a very high voltage electron gun needs to be designed.1 To these ends, several geometric parameters were were performed on off-axis electron acceleration. Introduction The design of the electrode gun has

  8. Electrodic voltages accompanying stimulated bioremediation of a uranium-contaminated aquifer

    SciTech Connect

    Williams, K.H.; N'Guessan, A.L.; Druhan, J.; Long, P.E.; Hubbard, S.S.; Lovley, D.R.; Banfield, J.F.

    2009-11-15

    The inability to track the products of subsurface microbial activity during stimulated bioremediation has limited its implementation. We used spatiotemporal changes in electrodic potentials (EP) to track the onset and persistence of stimulated sulfate-reducing bacteria in a uranium-contaminated aquifer undergoing acetate amendment. Following acetate injection, anomalous voltages approaching -900 mV were measured between copper electrodes within the aquifer sediments and a single reference electrode at the ground surface. Onset of EP anomalies correlated in time with both the accumulation of dissolved sulfide and the removal of uranium from groundwater. The anomalies persisted for 45 days after halting acetate injection. Current-voltage and current-power relationships between measurement and reference electrodes exhibited a galvanic response, with a maximum power density of 10 mW/m{sup 2} during sulfate reduction. We infer that the EP anomalies resulted from electrochemical differences between geochemically reduced regions and areas having higher oxidation potential. Following the period of sulfate reduction, EP values ranged from -500 to -600 mV and were associated with elevated concentrations of ferrous iron. Within 10 days of the voltage decrease, uranium concentrations rebounded from 0.2 to 0.8 {mu}M, a level still below the background value of 1.5 {mu}M. These findings demonstrate that EP measurements provide an inexpensive and minimally invasive means for monitoring the products of stimulated microbial activity within aquifer sediments and are capable of verifying maintenance of redox conditions favorable for the stability of bioreduced contaminants, such as uranium.

  9. Arc voltage measurements of the hyperbaric MIG process

    SciTech Connect

    Huismann, G.; Hoffmeister, H.

    1996-12-01

    As a vital part of the MIG process, the arc controls the stability of the process, the melting of the filler wire and the base material. In order to control and describe the arc behavior, it is necessary to know the voltage- current- arc length relations, or the arc characteristics. Knowledge of arc characteristics is necessary for control of the MIG process and further automation of welding systems, in particular, at hyperbaric welding. In literature, information on arc characteristics for hyperbaric open arc pulsed process is not available so far. Therefore, in the present work, arc characteristics were measured for a pressure range of 1 to 16 bar. In measuring arc voltages and arc lengths of MIG arcs, specific problems are encountered as compared to TIG arcs where the distance between the electrode and work piece can be taken as the arc length and the ohmic voltage drop in the tungsten electrode is low. The movement of the electrode in the MIG process and the deformation of the molten wire end together with weld pool fluctuations are providing a complex system. For determining the arc characteristics certain simplifications are thus required which have been applied in this work. This paper presents a new concept on measuring arc lengths and voltages in the open MIG arc.

  10. High voltage and high specific capacity dual intercalating electrode Li-ion batteries

    NASA Technical Reports Server (NTRS)

    West, William C. (Inventor); Blanco, Mario (Inventor)

    2010-01-01

    The present invention provides high capacity and high voltage Li-ion batteries that have a carbonaceous cathode and a nonaqueous electrolyte solution comprising LiF salt and an anion receptor that binds the fluoride ion. The batteries can comprise dual intercalating electrode Li ion batteries. Methods of the present invention use a cathode and electrode pair, wherein each of the electrodes reversibly intercalate ions provided by a LiF salt to make a high voltage and high specific capacity dual intercalating electrode Li-ion battery. The present methods and systems provide high-capacity batteries particularly useful in powering devices where minimizing battery mass is important.

  11. Measuring breakdown voltage for objectively detecting ignition in fire research

    NASA Astrophysics Data System (ADS)

    Ochoterena, R.; Försth, M.; Elfsberg, Mattias; Larsson, Anders

    2013-10-01

    This paper presents a method intended for detecting the initiation of combustion and the presence of smoke in confined or open spaces by continuously applying an intermittent high-voltage pulse between the electrodes. The method is based on an electrical circuit which generates an electrical discharge measuring simultaneously the breakdown voltage between the electrodes. It has been successfully used for the detection of particle-laden aerosols and flames. However, measurements in this study showed that detecting pyrolysis products with this methodology is challenging and arduous. The method presented here is robust and exploits the necessity of having an ignition system which at the same time can automatically discern between clean air, flames or particle-laden aerosols and can be easily implemented in the existing cone calorimeter with very minor modifications.

  12. TiN coated aluminum electrodes for DC high voltage electron guns

    SciTech Connect

    Mamun, Md Abdullah A.; Elmustafa, Abdelmageed A.; Taus, Rhys; Forman, Eric; Poelker, Matthew

    2015-05-01

    Preparing electrodes made of metals like stainless steel, for use inside DC high voltage electron guns, is a labor-intensive and time-consuming process. In this paper, the authors report the exceptional high voltage performance of aluminum electrodes coated with hard titanium nitride (TiN). The aluminum electrodes were comparatively easy to manufacture and required only hours of mechanical polishing using silicon carbide paper, prior to coating with TiN by a commercial vendor. The high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, was compared to that of bare aluminum electrodes, and electrodes manufactured from titanium alloy (Ti-6AI-4V). Following gas conditioning, each TiN-coated aluminum electrode reached -225 kV bias voltage while generating less than 100 pA of field emission (<10 pA) using a 40 mm cathode/anode gap, corresponding to field strength of 13.7 MV/m. Smaller gaps were studied to evaluate electrode performance at higher field strength with the best performing TiN-coated aluminum electrode reaching ~22.5 MV/m with field emission less than 100 pA. These results were comparable to those obtained from our best-performing electrodes manufactured from stainless steel, titanium alloy and niobium, as reported in references cited below. The TiN coating provided a very smooth surface and with mechanical properties of the coating (hardness and modulus) superior to those of stainless steel, titanium-alloy, and niobium electrodes. These features likely contributed to the improved high voltage performance of the TiN-coated aluminum electrodes.

  13. TiN coated aluminum electrodes for DC high voltage electron guns

    SciTech Connect

    Mamun, Md Abdullah A.; Elmustafa, Abdelmageed A.; Taus, Rhys; Forman, Eric; Poelker, Matthew

    2015-05-15

    Preparing electrodes made of metals like stainless steel, for use inside DC high voltage electron guns, is a labor-intensive and time-consuming process. In this paper, the authors report the exceptional high voltage performance of aluminum electrodes coated with hard titanium nitride (TiN). The aluminum electrodes were comparatively easy to manufacture and required only hours of mechanical polishing using silicon carbide paper, prior to coating with TiN by a commercial vendor. The high voltage performance of three TiN-coated aluminum electrodes, before and after gas conditioning with helium, was compared to that of bare aluminum electrodes, and electrodes manufactured from titanium alloy (Ti-6Al-4V). Following gas conditioning, each TiN-coated aluminum electrode reached ?225?kV bias voltage while generating less than 100?pA of field emission (<10?pA) using a 40?mm cathode/anode gap, corresponding to field strength of 13.7?MV/m. Smaller gaps were studied to evaluate electrode performance at higher field strength with the best performing TiN-coated aluminum electrode reaching ?22.5 MV/m with field emission less than 100?pA. These results were comparable to those obtained from our best-performing electrodes manufactured from stainless steel, titanium alloy and niobium, as reported in references cited below. The TiN coating provided a very smooth surface and with mechanical properties of the coating (hardness and modulus) superior to those of stainless steel, titanium-alloy, and niobium electrodes. These features likely contributed to the improved high voltage performance of the TiN-coated aluminum electrodes.

  14. Novel high-voltage power lateral MOSFET with adaptive buried electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Wen-Tong; Wu, Li-Juan; Qiao, Ming; Luo, Xiao-Rong; Zhang, Bo; Li, Zhao-Ji

    2012-07-01

    A new high-voltage and low-specific on-resistance (Ron,sp) adaptive buried electrode (ABE) silicon-on-insulator (SOI) power lateral MOSFET and its analytical model of the electric fields are proposed. The MOSFET features are that the electrodes are in the buried oxide (BOX) layer, the negative drain voltage Vd is divided into many partial voltages and the output to the electrodes is in the buried oxide layer and the potentials on the electrodes change linearly from the drain to the source. Because the interface silicon layer potentials are lower than the neighboring electrode potentials, the electronic potential wells are formed above the electrode regions, and the hole potential wells are formed in the spacing of two neighbouring electrode regions. The interface hole concentration is much higher than the electron concentration through designing the buried layer electrode potentials. Based on the interface charge enhanced dielectric layer field theory, the electric field strength in the buried layer is enhanced. The vertical electric field EI and the breakdown voltage (BV) of ABE SOI are 545 V/?m and -587 V in the 50 ?m long drift region and the 1 ?m thick dielectric layer, and a low Ron,sp is obtained. Furthermore, the structure also alleviates the self-heating effect (SHE). The analytical model matches the simulation results.

  15. Thermoelectric corrections to quantum voltage measurement

    NASA Astrophysics Data System (ADS)

    Bergfield, Justin P.; Stafford, Charles A.

    2014-12-01

    A generalization of Büttiker's voltage probe concept for nonzero temperatures is an open third terminal of a quantum thermoelectric circuit. An explicit analytic expression for the thermoelectric correction to an ideal quantum voltage measurement in linear response is derived and interpreted in terms of local Peltier cooling/heating within the nonequilibrium system. The thermoelectric correction is found to be large (up to ±24 % of the peak voltage) in a prototypical ballistic quantum conductor (graphene nanoribbon). The effects of measurement nonideality are also investigated. Our findings have important implications for precision local electrical measurements.

  16. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail, III, William Banning (Bothell, WA); Momii, Steven Thomas (Seattle, WA)

    2001-01-01

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  17. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail, III, William Banning (Bothell, WA); Momii, Steven Thomas (Seattle, WA)

    2000-01-01

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  18. Improving the performance of stainless-steel DC high voltage photoelectron gun cathode electrodes via gas conditioning with helium or krypton

    SciTech Connect

    Bastaninejad, Mahzad; Elmustafa, Abdelmageed; Forman, Eric I.; Clark, James; Covert, Steven R.; Grames, Joseph M.; Hansknecht, John C.; Hernandez-Garcia, Carlos; Poelker, Bernard; Suleiman, Riad S.

    2014-10-01

    Gas conditioning was shown to eliminate field emission from cathode electrodes used inside DC high voltage photoelectron guns, thus providing a reliable means to operate photoguns at higher voltages and field strengths. Measurements and simulation results indicate that gas conditioning eliminates field emission from cathode electrodes via two mechanisms: sputtering and implantation, with the benefits of implantation reversed by heating the electrode. We have studied five stainless steel electrodes (304L and 316LN) that were polished to approximately 20 nm surface roughness using diamond grit, and evaluated inside a high voltage apparatus to determine the onset of field emission as a function of voltage and field strength. The field emission characteristics of each electrode varied significantly upon the initial application of voltage but improved to nearly the same level after gas conditioning using either helium or krypton, exhibiting less than 10 pA field emission at ?225 kV bias voltage with a 50 mm cathode/anode gap, corresponding to a field strength of ~13 MV/m. Field emission could be reduced with either gas, but there were conditions related to gas choice, voltage and field strength that were more favorable than others.

  19. Sheath expansion of two-dimensional grid electrodes subjected to short pulses of negative high-voltage

    NASA Astrophysics Data System (ADS)

    Yi, Changho; Lee, Huijea; Park, Byungjae; Namkung, Won; Cho, Moohyun

    2015-02-01

    Sheath expansion was investigated for two-dimensional (2D) grid electrodes which consist of a periodic array of cylindrical electrodes when short pulses of negative high-voltage were applied to the electrodes immersed in plasmas. In the sheath expansion model, a geometric function which describes the electrode system is crucial to numerically calculate the temporal evolution of a sheath boundary. In this paper, the 2D geometric function of grid electrodes was obtained by using XOOPIC (particle-in-cell) simulation. When the ratio between the diameter of cylindrical electrodes and grid spacing is fixed, we found that the geometric functions and the temporal evolutions of the sheath boundary for grid electrodes are identical in normalized coordinates. The numerical calculation results of the temporal evolutions of the sheath boundary showed reasonable agreements with the experimental measurements carried out in argon plasmas produced by hot filament discharges with neutral gas pressure of ˜0.4 mTorr and plasma density in the order of 1010 cm-3 in a multi-dipole device.

  20. Rapidly prototyped multi-scale electrodes to minimize the voltage requirements for bacterial cell lysis.

    PubMed

    Gabardo, Christine M; Kwong, Aaron M; Soleymani, Leyla

    2015-03-01

    Lab-on-a-chip systems used for nucleic acid based detection of bacteria rely on bacterial lysis for the release of cellular material. Although electrical lysis devices can be miniaturized for on-chip integration and reagent-free lysis, they often suffer from high voltage requirements, and rely on the use of off-chip voltage supplies. To overcome this barrier, we developed a rapid prototyping method for creating multi-scale electrodes that are structurally tuned for lowering the voltage needed for electrical bacterial lysis. These three-dimensional multi-scale electrodes – with micron scale reaction areas and nanoscale features – are fabricated using benchtop methods including craft cutting, polymer-induced wrinkling, and electrodeposition, which enable a lysis device to be designed, fabricated, and optimized in a matter of hours. These tunable electrodes show superior behaviour compared to lithographically-prepared electrodes in terms of lysis efficiency and voltage requirement. Successful extraction of nucleic acids from bacterial samples processed by these electrodes demonstrates the potential for these rapidly prototyped devices to be integrated within practical lab-on-a-chip systems. PMID:25597363

  1. Fiber-optic voltage measuring system

    NASA Astrophysics Data System (ADS)

    Ye, Miaoyuan; Nie, De-Xin; Li, Yan; Peng, Yu; Lin, Qi-Qing; Wang, Jing-Gang

    1993-09-01

    A new fibre optic voltage measuring system has been developed based on the electrooptic effect of bismuth germanium oxide (Bi4Ge3O12)crystal. It uses the LED as the light source. The light beam emitted from the light source is transmitted to the sensor through the optic fibre and the intensity of the output beam is changed by the applied voltage. This optic signal is transmitted to the PIN detector and converted to an electric signal which is processed by the electronic circuit and 8098 single chip microcomputer the output voltage signal obtained is directly proportional to the applied voltage. This paper describes the principle the configuration and the performance parameters of the system. Test results are evaluated and discussed.

  2. Transition voltages of vacuum-spaced and molecular junctions with Ag and Pt electrodes

    SciTech Connect

    Wu, Kunlin; Bai, Meilin; Hou, Shimin; Sanvito, Stefano

    2014-07-07

    The transition voltage of vacuum-spaced and molecular junctions constructed with Ag and Pt electrodes is investigated by non-equilibrium Green's function formalism combined with density functional theory. Our calculations show that, similarly to the case of Au-vacuum-Au previously studied, the transition voltages of Ag and Pt metal-vacuum-metal junctions with atomic protrusions on the electrode surface are determined by the local density of states of the p-type atomic orbitals of the protrusion. Since the energy position of the Pt 6p atomic orbitals is higher than that of the 5p/6p of Ag and Au, the transition voltage of Pt-vacuum-Pt junctions is larger than that of both Ag-vacuum-Ag and Au-vacuum-Au junctions. When one moves to analyzing asymmetric molecular junctions constructed with biphenyl thiol as central molecule, then the transition voltage is found to depend on the specific bonding site for the sulfur atom in the thiol group. In particular agreement with experiments, where the largest transition voltage is found for Ag and the smallest for Pt, is obtained when one assumes S binding at the hollow-bridge site on the Ag/Au(111) surface and at the adatom site on the Pt(111) one. This demonstrates the critical role played by the linker-electrode binding geometry in determining the transition voltage of devices made of conjugated thiol molecules.

  3. Transition voltages of vacuum-spaced and molecular junctions with Ag and Pt electrodes.

    PubMed

    Wu, Kunlin; Bai, Meilin; Sanvito, Stefano; Hou, Shimin

    2014-07-01

    The transition voltage of vacuum-spaced and molecular junctions constructed with Ag and Pt electrodes is investigated by non-equilibrium Green's function formalism combined with density functional theory. Our calculations show that, similarly to the case of Au-vacuum-Au previously studied, the transition voltages of Ag and Pt metal-vacuum-metal junctions with atomic protrusions on the electrode surface are determined by the local density of states of the p-type atomic orbitals of the protrusion. Since the energy position of the Pt 6p atomic orbitals is higher than that of the 5p/6p of Ag and Au, the transition voltage of Pt-vacuum-Pt junctions is larger than that of both Ag-vacuum-Ag and Au-vacuum-Au junctions. When one moves to analyzing asymmetric molecular junctions constructed with biphenyl thiol as central molecule, then the transition voltage is found to depend on the specific bonding site for the sulfur atom in the thiol group. In particular agreement with experiments, where the largest transition voltage is found for Ag and the smallest for Pt, is obtained when one assumes S binding at the hollow-bridge site on the Ag/Au(111) surface and at the adatom site on the Pt(111) one. This demonstrates the critical role played by the linker-electrode binding geometry in determining the transition voltage of devices made of conjugated thiol molecules. PMID:25005303

  4. Averaged electrode voltages in users of the Clarion cochlear implant device.

    PubMed

    Mens, Lucas H M; Mulder, Jef J S

    2002-04-01

    Averaged electrode voltages (AEVs) are of secondary importance for integrity testing of cochlear implant devices featuring back-telemetry. However, AEVs are device-independent and may show intermittent failures and deviant stimulation patterns unnoticed by telemetry. We collected AEVs from 18 users of the Clarion 1.2 system and 6 users of the HiFocus system in order to establish norms for evaluating AEVs in difficult cases. The stimuli were presented with the standard clinical software. Monopolar stimulation at about 16 microA showed large AEVs (mean, 173 microV) suitable for integrity testing. No electrode failures were found. The AEV amplitudes from neighboring electrodes differed by less than 30% (2 SD). The AEVs from subjects with the Clarion HiFocus electrode and/or the Clarion electrode positioner were within the normal range. The AEV amplitudes from bipolar stimulation were much more variable. Inversion of phases between electrodes was found in patients with an altered state of the cochlea (otosclerosis and osteogenesis imperfecta) and in a patient with a curled electrode tip. There was no correlation across subjects between AEVs and electrode impedances. Therefore, impedances are dominated by the electrode-tissue interface, in contrast to AEVs, which are determined by the volume conduction in the body. PMID:11991591

  5. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

    DOE PAGESBeta

    BastaniNejad, Mahzad; Elmustafa, Abdelmageed A.; Forman, Eric; Covert, Steven; Hansknecht, John; Hernandez-Garcia, Carlos; Poelker, Matthew; Das, Lopa; Kelley, Michael; Williams, Phillip

    2015-07-01

    DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (~nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>?A) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolishedmore »by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.« less

  6. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

    SciTech Connect

    BastaniNejad, Mahzad; Elmustafa, Abdelmageed A.; Forman, Eric; Covert, Steven; Hansknecht, John; Hernandez-Garcia, Carlos; Poelker, Matthew; Das, Lopa; Kelley, Michael; Williams, Phillip

    2015-07-01

    DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (~nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>?A) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolished by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100 pA of field emission. The speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.

  7. Evaluation of electropolished stainless steel electrodes for use in DC high voltage photoelectron guns

    SciTech Connect

    BastaniNejad, Mahzad Elmustafa, Abdelmageed A.; Forman, Eric; Covert, Steven; Hansknecht, John; Hernandez-Garcia, Carlos; Poelker, Matthew; Das, Lopa; Kelley, Michael; Williams, Phillip

    2015-07-15

    DC high voltage photoelectron guns are used to produce polarized electron beams for accelerator-based nuclear and high-energy physics research. Low-level field emission (?nA) from the cathode electrode degrades the vacuum within the photogun and reduces the photoelectron yield of the delicate GaAs-based photocathode used to produce the electron beams. High-level field emission (>?A) can cause significant damage the photogun. To minimize field emission, stainless steel electrodes are typically diamond-paste polished, a labor-intensive process often yielding field emission performance with a high degree of variability, sample to sample. As an alternative approach and as comparative study, the performance of electrodes electropolished by conventional commercially available methods is presented. Our observations indicate the electropolished electrodes exhibited less field emission upon the initial application of high voltage, but showed less improvement with gas conditioning compared to the diamond-paste polished electrodes. In contrast, the diamond-paste polished electrodes responded favorably to gas conditioning, and ultimately reached higher voltages and field strengths without field emission, compared to electrodes that were only electropolished. The best performing electrode was one that was both diamond-paste polished and electropolished, reaching a field strength of 18.7 MV/m while generating less than 100?pA of field emission. The authors speculate that the combined processes were the most effective at reducing both large and small scale topography. However, surface science evaluation indicates topography cannot be the only relevant parameter when it comes to predicting field emission performance.

  8. Comparison of three current sources for single-electrode capacitance measurement

    NASA Astrophysics Data System (ADS)

    Chen, D. X.; Deng, X.; Yang, W. Q.

    2010-03-01

    The capacitance of a single electrode is usually measured by injecting a current to the electrode and measuring the resultant voltage on the electrode. In this case, a voltage-controlled current source with a high bandwidth is needed because the impedance is inversely proportional to the excitation frequency. In this design note, three different current sources are discussed: (1) the Howland current source, (2) a modified Howland current source, and (3) a dual op-amp current source. The principle and dynamic performances are presented and compared. Simulation and experimental results show that although the Howland current source has the lowest (i.e., worst) output impedance, its output is the most stable among the three current sources when the frequency changes. Therefore, it is suitable for single-electrode capacitance measurement. Initial tests have proven the feasibility of single-electrode capacitance sensor with the Howland current source.

  9. Programming voltage reduction in phase change memory cells with tungsten trioxide bottom heating layer/electrode.

    PubMed

    Rao, Feng; Song, Zhitang; Gong, Yuefeng; Wu, Liangcai; Feng, Songlin; Chen, Bomy

    2008-11-01

    A phase change memory cell with tungsten trioxide bottom heating layer/electrode is investigated. The crystalline tungsten trioxide heating layer promotes the temperature rise in the Ge(2)Sb(2)Te(5) layer which causes the reduction in the reset voltage compared to a conventional phase change memory cell. Theoretical thermal simulation and calculation for the reset process are applied to understand the thermal effect of the tungsten trioxide heating layer/electrode. The improvement in thermal efficiency of the PCM cell mainly originates from the low thermal conductivity of the crystalline tungsten trioxide material. PMID:21832748

  10. General method to predict voltage-dependent ionic conduction in a solid electrolyte coating on electrodes

    NASA Astrophysics Data System (ADS)

    Pan, Jie; Cheng, Yang-Tse; Qi, Yue

    2015-04-01

    Understanding the ionic conduction in solid electrolytes in contact with electrodes is vitally important to many applications, such as lithium ion batteries. The problem is complex because both the internal properties of the materials (e.g., electronic structure) and the characteristics of the externally contacting phases (e.g., voltage of the electrode) affect defect formation and transport. In this paper, we developed a method based on density functional theory to study the physics of defects in a solid electrolyte in equilibrium with an external environment. This method was then applied to predict the ionic conduction in lithium fluoride (LiF), in contact with different electrodes which serve as reservoirs with adjustable Li chemical potential (?Li) for defect formation. LiF was chosen because it is a major component in the solid electrolyte interphase (SEI) formed on lithium ion battery electrodes. Seventeen possible native defects with their relevant charge states in LiF were investigated to determine the dominant defect types on various electrodes. The diffusion barrier of dominant defects was calculated by the climbed nudged elastic band method. The ionic conductivity was then obtained from the concentration and mobility of defects using the Nernst-Einstein relationship. Three regions for defect formation were identified as a function of ?Li: (1) intrinsic, (2) transitional, and (3) p -type region. In the intrinsic region (high ?Li, typical for LiF on the negative electrode), the main defects are Schottky pairs and in the p -type region (low ?Li, typical for LiF on the positive electrode) are Li ion vacancies. The ionic conductivity is calculated to be approximately 10-31Scm-1 when LiF is in contact with a negative electrode but it can increase to 10-12Scm-1 on a positive electrode. This insight suggests that divalent cation (e.g., Mg2+) doping is necessary to improve Li ion transport through the engineered LiF coating, especially for LiF on negative electrodes. Our results provide an understanding of the influence of the environment on defect formation and demonstrate a linkage between defect concentration in a solid electrolyte and the voltage of the electrode.

  11. Ultra-low voltage ferroelectric electron emission from lead zirconate titanate thin films with nanostructured top electrodes

    NASA Astrophysics Data System (ADS)

    Becherer, J.; Mieth, O.; Vidyarthi, V. S.; Gerlach, G.; Eng, L. M.

    2011-07-01

    Electron emission from thin ferroelectric Pb(Zr0.4 Ti0.6)O3 films is demonstrated reaching emission current densities of up to 3×10-8 A cm-2 for pulsed excitation voltages of 60 V. Nevertheless, the emission process sets in at voltages as low as 10 V. Thin lead zirconate titanate (PZT) films were prepared with a structured top electrode, which exhibits nanometer-sized regularly arranged apertures. The emission current was measured under UHV conditions by both a single electron detector for small emission currents and an amperemeter for larger currents. The voltage dependent polarization state within the emission apertures was imaged using piezoresponse force microscopy and revealed that an increased fraction of the free surface area is switched by an increased applied voltage. This shows that the emission process is strongly correlated to the switching of ferroelectric polarization. Moreover, with the help of a metal grid in front of the detector, the maximum kinetic energy of emitted electrons was investigated and found to be limited by the excitation voltage, only.

  12. The Effect of the Earthed Electrode Size on the Ignition Voltage of Low-Pressure RF Capacitive Discharge in Argon

    NASA Astrophysics Data System (ADS)

    A. Azooz, A.; A. Ahmad, M.

    2013-09-01

    The effect of the grounded electrode diameter on the ignition voltage using 13.56 MHz in argon gas is studied experimentally. The results indicate a systematic decrease of the breakdown voltage with increasing electrode area for the same pd value. No multi-valued breakdown voltages are observed. The Paschen minimum is not affected by the electrode diameter as long as the parallel plane approximation is valid. A modified Paschen equation which takes into account indirect discharge via the chamber walls at high pd values gives reasonable fits to the experimental data.

  13. Electrowetting on dielectric device with crescent electrodes for reliable and low-voltage droplet manipulation.

    PubMed

    Xu, Xiaowei; Sun, Lining; Chen, Liguo; Zhou, Zhaozhong; Xiao, Junjian; Zhang, Yuliang

    2014-11-01

    Digital microfluidics based on electrowetting on dielectric is an emerging popular technology that manipulates single droplets at the microliter or even the nanoliter level. It has the unique advantages of rapid response, low reagent consumption, and high integration and is mainly applied in the field of biochemical analysis. However, currently, this technology still has a few problems, such as high control voltage, low droplet velocity, and continuity in flow, limiting its application. In this paper, through theoretical analysis and numerical simulation, it is deduced that a drive electrode with a crescent configuration can reduce the driving voltage. The experimental results not only validate this deduction but also indicate that crescent electrode can improve the droplet motion continuity and the success in split rate. PMID:25553184

  14. Electrowetting on dielectric device with crescent electrodes for reliable and low-voltage droplet manipulation

    PubMed Central

    Xu, Xiaowei; Sun, Lining; Chen, Liguo; Zhou, Zhaozhong; Xiao, Junjian; Zhang, Yuliang

    2014-01-01

    Digital microfluidics based on electrowetting on dielectric is an emerging popular technology that manipulates single droplets at the microliter or even the nanoliter level. It has the unique advantages of rapid response, low reagent consumption, and high integration and is mainly applied in the field of biochemical analysis. However, currently, this technology still has a few problems, such as high control voltage, low droplet velocity, and continuity in flow, limiting its application. In this paper, through theoretical analysis and numerical simulation, it is deduced that a drive electrode with a crescent configuration can reduce the driving voltage. The experimental results not only validate this deduction but also indicate that crescent electrode can improve the droplet motion continuity and the success in split rate. PMID:25553184

  15. dc step response of induced-charge electro-osmosis between parallel electrodes at large voltages

    NASA Astrophysics Data System (ADS)

    Sugioka, Hideyuki

    2014-07-01

    Induced-charge electro-osmosis (ICEO) is important since it can be used for realizing high performance microfluidic devices. Here, we analyze the simplest problem of ion relaxation around a circular polarizable cylinder between parallel blocking electrodes in a closed cell by using a multiphysics coupled simulation technique. This technique is based on a combination of the finite-element method and finite-volume method for the Poisson-Nernst-Planck (PNP) equations having a flow term and the Stokes equation having an electric stress term. Through this analysis, we successfully demonstrate that on application of dc voltages, quadorapolar ICEO vortex flows grow during the charging time of the cylinder for both unbounded and bounded problems and decay during the charging time of the parallel electrodes only for the bounded problem using blocking electrodes. Further, by proposing a simple model that considers the two-dimensional (2D) PNP equations analytically, we successfully explain the step response time of the ICEO flow for the both unbounded and bounded problems. Furthermore, at low applied voltages, we find analytical formulations on steady diffused-ion problems and steady ICEO-flow problems and examine that our numerical results agree well with the analytical results. Moreover, by considering an ion-conserving condition with 2D Poisson-Boltzmann equations, we explain significant decrease of the maximum slip velocity at large applied voltages fairly well. We believe that our analysis will contribute greatly to the realistic designs of prospective high-performance microfluidic devices.

  16. dc Step response of induced-charge electro-osmosis between parallel electrodes at large voltages.

    PubMed

    Sugioka, Hideyuki

    2014-07-01

    Induced-charge electro-osmosis (ICEO) is important since it can be used for realizing high performance microfluidic devices. Here, we analyze the simplest problem of ion relaxation around a circular polarizable cylinder between parallel blocking electrodes in a closed cell by using a multiphysics coupled simulation technique. This technique is based on a combination of the finite-element method and finite-volume method for the Poisson-Nernst-Planck (PNP) equations having a flow term and the Stokes equation having an electric stress term. Through this analysis, we successfully demonstrate that on application of dc voltages, quadorapolar ICEO vortex flows grow during the charging time of the cylinder for both unbounded and bounded problems and decay during the charging time of the parallel electrodes only for the bounded problem using blocking electrodes. Further, by proposing a simple model that considers the two-dimensional (2D) PNP equations analytically, we successfully explain the step response time of the ICEO flow for the both unbounded and bounded problems. Furthermore, at low applied voltages, we find analytical formulations on steady diffused-ion problems and steady ICEO-flow problems and examine that our numerical results agree well with the analytical results. Moreover, by considering an ion-conserving condition with 2D Poisson-Boltzmann equations, we explain significant decrease of the maximum slip velocity at large applied voltages fairly well. We believe that our analysis will contribute greatly to the realistic designs of prospective high-performance microfluidic devices. PMID:25122369

  17. Electronic circuit for measuring series connected electrochemical cell voltages

    DOEpatents

    Ashtiani, Cyrus N. (West Bloomfield, MI); Stuart, Thomas A. (Toledo, OH)

    2000-01-01

    An electronic circuit for measuring voltage signals in an energy storage device is disclosed. The electronic circuit includes a plurality of energy storage cells forming the energy storage device. A voltage divider circuit is connected to at least one of the energy storage cells. A current regulating circuit is provided for regulating the current through the voltage divider circuit. A voltage measurement node is associated with the voltage divider circuit for producing a voltage signal which is proportional to the voltage across the energy storage cell.

  18. Experimental validation of a high voltage pulse measurement method.

    SciTech Connect

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobate's (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps - 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensor's U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  19. How Voltage Drops are Manifested by Lithium Ion Configurations at Interfaces and in Thin Films on Battery Electrodes

    E-print Network

    Leung, Kevin

    2015-01-01

    Battery electrode surfaces are generally coated with electronically insulating solid films of thickness 1-50 nm. Both electrons and Li+ can move at the electrode-surface film interface in response to the voltage, which adds complexity to the "electric double layer" (EDL). We apply Density Functional Theory (DFT) to investigate how the applied voltage is manifested as changes in the EDL at atomic lengthscales, including charge separation and interfacial dipole moments. Illustrating examples include Li(3)PO(4), Li(2)CO(3), and Li(x)Mn(2)O(4) thin-films on Au(111) surfaces under ultrahigh vacuum conditions. Adsorbed organic solvent molecules can strongly reduce voltages predicted in vacuum. We propose that manipulating surface dipoles, seldom discussed in battery studies, may be a viable strategy to improve electrode passivation. We also distinguish the computed potential governing electrons, which is the actual or instantaneous voltage, and the "lithium cohesive energy" based voltage governing Li content widely...

  20. Electrodic voltages in the presence of dissolved sulfide: Implications for monitoring natural microbial activity

    SciTech Connect

    Slater, L.; Ntarlagiannis, D.; Yee, N.; O'Brien, M.; Zhang, C.; Williams, K. H.

    2008-10-01

    There is growing interest in the development of new monitoring strategies for obtaining spatially extensive data diagnostic of microbial processes occurring in the earth. Open-circuit potentials arising from variable redox conditions in the fluid local-to-electrode surfaces (electrodic potentials) were recorded for a pair of silver-silver chloride electrodes in a column experiment, whereby a natural wetland soil containing a known community of sulfate reducers was continuously fed with a sulfate-rich nutrient medium. Measurements were made between five electrodes equally spaced along the column and a reference electrode placed on the column inflow. The presence of a sulfate reducing microbial population, coupled with observations of decreasing sulfate levels, formation of black precipitate (likely iron sulfide),elevated solid phase sulfide, and a characteristic sulfurous smell, suggest microbial-driven sulfate reduction (sulfide generation) in our column. Based on the known sensitivity of a silver electrode to dissolved sulfide concentration, we interpret the electrodic potentials approaching 700 mV recorded in this experiment as an indicator of the bisulfide (HS-) concentration gradients in the column. The measurement of the spatial and temporal variation in these electrodic potentials provides a simple and rapid method for monitoring patterns of relative HS- concentration that are indicative of the activity of sulfate-reducing bacteria. Our measurements have implications both for the autonomous monitoring of anaerobic microbial processes in the subsurface and the performance of self-potential electrodes, where it is critical to isolate, and perhaps quantify, electrochemical interfaces contributing to observed potentials.

  1. Performance measurements of advanced AMTEC electrodes

    NASA Astrophysics Data System (ADS)

    Schuller, Michael; Fiebig, Brad; Hudson, Patricia; Kakwan, Imran

    2000-01-01

    These results are from sodium exposure test cell experiments with advanced AMTEC electrodes performed at Texas A&M University. The majority of the results are for metal electrodes; the minority of the results are for ceramic electrodes. Initial results for iridium and titanate electrodes have been good, but degrade with time. .

  2. Analysis of NSTX TF Joint Voltage Measurements

    SciTech Connect

    R, Woolley

    2005-10-07

    This report presents findings of analyses of recorded current and voltage data associated with 72 electrical joints operating at high current and high mechanical stress. The analysis goal was to characterize the mechanical behavior of each joint and thus evaluate its mechanical supports. The joints are part of the toroidal field (TF) magnet system of the National Spherical Torus Experiment (NSTX) pulsed plasma device operating at the Princeton Plasma Physics Laboratory (PPPL). Since there is not sufficient space near the joints for much traditional mechanical instrumentation, small voltage probes were installed on each joint and their voltage monitoring waveforms have been recorded on sampling digitizers during each NSTX ''shot''.

  3. Electrophysiological Characterization of Na,K-ATPases Expressed in Xenopus laevis Oocytes Using Two-Electrode Voltage Clamping.

    PubMed

    Hilbers, Florian; Poulsen, Hanne

    2016-01-01

    The transport of three Na(+) per two K(+) means that the Na,K-ATPase is electrogenic, and though the currents generated by the ion pump are small compared to ion channel currents, they can be measured using electrophysiology, both steady-state pumping and individual steps in the transport cycle. Various electrophysiological techniques have been used to study the endogenous pumps of the squid giant axon and of cardiac myocytes from for example rabbits. Here, we describe the characterization of heterologously expressed Na,K-ATPases using two-electrode voltage clamping (TEVC) and oocytes from the Xenopus laevis frog as the model cell. With this system, the effects of particular mutations can be studied, including the numerous mutations that in later years have been found to cause human diseases. PMID:26695042

  4. Factors affecting the open-circuit voltage and electrode kinetics of some iron/titanium redox flow cells

    NASA Technical Reports Server (NTRS)

    Reid, M. A.; Gahn, R. F.

    1977-01-01

    Performance of the iron-titanium redox flow cell was studied as a function of acid concentration. Anion permeable membranes separated the compartments. Electrodes were graphite cloth. Current densities ranged up to 25 mA/square centimeter. Open-circuit and load voltages decreased as the acidity was increased on the iron side as predicted. On the titanium side, open-circuit voltages decreased as the acidity was increased in agreement with theory, but load voltages increased due to decreased polarization with increasing acidity. High acidity on the titanium side coupled with low acidity on the iron side gives the best load voltage, but such cells show voltage losses as they are repeatedly cycled. Analyses show that the bulk of the voltage losses are due to diffusion of acid through the membrane.

  5. Three-Dimensionally Mesostructured Fe2O3 Electrodes with Good Rate Performance and Reduced Voltage Hysteresis

    E-print Network

    Braun, Paul

    Hysteresis Junjie Wang, Hui Zhou, Jagjit Nanda,*,,§ and Paul V. Braun*, Department of Materials Science resulted in a reduced voltage hysteresis. The electrode showed a reversible capacity of 1000 mAh g-1 at 0 capacity was about 450 mAh g-1 . The room-temperature voltage hysteresis at 0.1 A g-1 (0.1 C) was 0.62 V

  6. Measurement of high voltage using Rutherford backscattering spectrometry 

    E-print Network

    Abrego, Celestino Pete

    2007-04-25

    A novel variation of Rutherford Backscattering Spectrometry (RBS) has been utilized to measure a high voltage collected on an aluminum target by Direct Energy Conversion. The maximum high voltage on the target was measured to be 97.5 kV +/- 2 k...

  7. Gelatin coated electrodes allow prolonged bioelectronic measurements

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Silver electrodes treated with an anodizing electrolyte containing gelatin are used for long term monitoring of bioelectronic potentials in humans. The electrodes do not interact with perspiration, cause skin irritation, or promote the growth of bacteria.

  8. Measuring Helical FCG Voltage with an Electric Field Antenna

    SciTech Connect

    White, A D; Anderson, R A; Javedani, J B; Reisman, D B; Goerz, D A; Ferriera, A J; Speer, R D

    2011-08-01

    A method of measuring the voltage produced by a helical explosive flux compression generator using a remote electric field antenna is described in detail. The diagnostic has been successfully implemented on several experiments. Measured data from the diagnostic compare favorably with voltages predicted using the code CAGEN, validating our predictive modeling tools. The measured data is important to understanding generator performance, and is measured with a low-risk, minimally intrusive approach.

  9. Design of an integrated thermoelectric generator power converter for ultra-low power and low voltage body energy harvesters aimed at ExG active electrodes

    NASA Astrophysics Data System (ADS)

    Ataei, Milad; Robert, Christian; Boegli, Alexis; Farine, Pierre-André

    2015-10-01

    This paper describes a detailed design procedure for an efficient thermal body energy harvesting integrated power converter. The procedure is based on the examination of power loss and power transfer in a converter for a self-powered medical device. The efficiency limit for the system is derived and the converter is optimized for the worst case scenario. All optimum system parameters are calculated respecting the transducer constraints and the application form factor. Circuit blocks including pulse generators are implemented based on the system specifications and optimized converter working frequency. At this working condition, it has been demonstrated that the wide area capacitor of the voltage doubler, which provides high voltage switch gating, can be eliminated at the expense of wider switches. With this method, measurements show that 54% efficiency is achieved for just a 20?mV transducer output voltage and 30% of the chip area is saved. The entire electronic board can fit in one EEG or ECG electrode, and the electronic system can convert the electrode to an active electrode.

  10. Three electrode measurements on solid electrolytes

    SciTech Connect

    Pham, A.Q.; Glass, R.S.

    1995-12-01

    AC impedance spectroscopy and chronopotentiometry have been used to study solid-state ionic conductors. Results obtained using three electrodes are compared to those using a two-electrode configuration. The uncompensated resistance was shown to depend strongly on the geometric placement of the electrodes. The optimal configuration for minimized uncompensated resistance effects is similar to the Luggin capillary arrangement in the liquid phase. The effect of non-negligible geometric capacitance on interpretation of results is discussed.

  11. Method for linearizing deflection of a MEMS device using binary electrodes and voltage modulation

    DOEpatents

    Horenstein, Mark N. (West Roxbury, MA) [West Roxbury, MA

    2008-06-10

    A micromechanical device comprising one or more electronically movable structure sets comprising for each set a first electrode supported on a substrate and a second electrode supported substantially parallel from said first electrode. Said second electrode is movable with respect to said first electrode whereby an electric potential applied between said first and second electrodes causing said second electrode to move relative to said first electrode a distance X, (X), where X is a nonlinear function of said potential, (V). Means are provided for linearizing the relationship between V and X.

  12. Traveling electric field probed by a fine particle above voltage-modulated strips in a striped electrode device

    SciTech Connect

    Li Yangfang; Jiang Ke; Thomas, H. M.; Morfill, G. E.; Zhang Wengui; Ma, J. X.

    2010-03-15

    It is described that the distribution of the horizontal electric field above a striped electrode can be inferred from the trajectory of a single fine particle with known mass and diameter. The striped electrode consists of 100 segmented stainless steel strips, each electrically insulated. A traveling periodic potential profile is produced above the striped electrode by modulating the voltage signals on the strips. When the voltage modulation is on, the fine particle, which is originally levitated in the sheath region above the striped electrode, experiences a periodic oscillation along both the vertical and the horizontal directions because of the periodic electric force arising from the modulation voltages. Tracking the motion of the fine particles, the electric force is obtained from the momentum equation including the gravity and the neutral gas friction. With the particle charge estimated by the vertical oscillation method, the electric field can be derived. The horizontal electric field obtained by this method is in agreement with the result predicted by a collisional particle-in-cell simulation.

  13. Voltage induced intensity changes in surface raman bands from a 2-chromophore probe, 4-benzyl pyridine adsorbed on roughened silver electrodes and their variation with excitation frequency

    NASA Astrophysics Data System (ADS)

    Busby, C. C.

    1984-05-01

    Voltage induced intensity changes in the surface enhanced Raman bands of 4-benzyl pyridine adsorbed on variously roughened silver electrode surfaces peak at different voltages for different excitation wavelengths. This behaviour, which is known to occur for pyridine and the picolines, is shown to occur for both the pyridyl and benzyl residues, though benzene itself does not exhibit enhancement under the same conditions. Results obtained on conventionally prepared, anodised electrodes are compared with those from novel magic array electrodes and results are consistent with the hypothesis that these latter electrodes are more suited for Raman studies of adsorbates in electrochemical systems. This is because they do not have the excess quantities of surface complexes present on them: these are probably responsible for much of the signal from the anodised electrodes. Explanations for the excitation frequency dependence of the voltage/intensity curves are discussed in relation to electrode specific effects as well as to charge transfer.

  14. Automated Evaluation of Dynamic Performance of Impulse Voltage Measurement Systems

    NASA Astrophysics Data System (ADS)

    Faria, L. C.; Silva, E. C.; Silva, M. T.; Barbosa, C. R. H.; Azevedo, L. C.

    2015-01-01

    This manuscript presents and describes an automated system for the evaluation of the dynamic performance of high-voltage measurement systems, according to the requirements of the standard IEC 60060-2/2010. The system was developed in LabVIEW and controls the acquisition, measurement and analysis of step response tests of measurement systems, automatically calculating the relevant amplitude and time parameters.

  15. Improved open-circuit voltage in Cu(In,Ga)Se2 solar cells with high work function transparent electrodes

    NASA Astrophysics Data System (ADS)

    Jäger, Timo; Romanyuk, Yaroslav E.; Bissig, Benjamin; Pianezzi, Fabian; Nishiwaki, Shiro; Reinhard, Patrick; Steinhauser, Jérôme; Schwenk, Johannes; Tiwari, Ayodhya N.

    2015-06-01

    Hydrogenated indium oxide (IOH) is implemented as transparent front contact in Cu(In,Ga)Se2 (CIGS) solar cells, leading to an open circuit voltage VOC enhanced by ˜20 mV as compared to reference devices with ZnO:Al (AZO) electrodes. This effect is reproducible in a wide range of contact sheet resistances corresponding to various IOH thicknesses. We present the detailed electrical characterization of glass/Mo/CIGS/CdS/intrinsic ZnO (i-ZnO)/transparent conductive oxide (TCO) with different IOH/AZO ratios in the front TCO contact in order to identify possible reasons for the enhanced VOC. Temperature and illumination intensity-dependent current-voltage measurements indicate that the dominant recombination path does not change when AZO is replaced by IOH, and it is mainly limited to recombination in the space charge region and at the junction interface of the solar cell. The main finding is that the introduction of even a 5 nm-thin IOH layer at the i-ZnO/TCO interface already results in a step-like increase in VOC. Two possible explanations are proposed and verified by one-dimensional simulations using the SCAPS software. First, a higher work function of IOH as compared to AZO is simulated to yield an VOC increase by 21 mV. Second, a lower defect density in the i-ZnO layer as a result of the reduced sputter damage during milder sputter-deposition of IOH can also add to a maximum enhanced VOC of 25 mV. Our results demonstrate that the proper choice of the front TCO contact can reduce the parasitic recombination and boost the efficiency of CIGS cells with improved corrosion stability.

  16. Beam based measurement of beam position monitor electrode gains

    NASA Astrophysics Data System (ADS)

    Rubin, D. L.; Billing, M.; Meller, R.; Palmer, M.; Rendina, M.; Rider, N.; Sagan, D.; Shanks, J.; Strohman, C.

    2010-09-01

    Low emittance tuning at the Cornell Electron Storage Ring (CESR) test accelerator depends on precision measurement of vertical dispersion and transverse coupling. The CESR beam position monitors (BPMs) consist of four button electrodes, instrumented with electronics that allow acquisition of turn-by-turn data. The response to the beam will vary among the four electrodes due to differences in electronic gain and/or misalignment. This variation in the response of the BPM electrodes will couple real horizontal offset to apparent vertical position, and introduce spurious measurements of coupling and vertical dispersion. To alleviate this systematic effect, a beam based technique to measure the relative response of the four electrodes has been developed. With typical CESR parameters, simulations show that turn-by-turn BPM data can be used to determine electrode gains to within ˜0.1%.

  17. Understanding capacity fade in silicon based electrodes for lithium-ion batteries using three electrode cells and upper cut-off voltage studies

    NASA Astrophysics Data System (ADS)

    Beattie, Shane D.; Loveridge, M. J.; Lain, Michael J.; Ferrari, Stefania; Polzin, Bryant J.; Bhagat, Rohit; Dashwood, Richard

    2016-01-01

    Commercial Li-ion batteries are typically cycled between 3.0 and 4.2 V. These voltages limits are chosen based on the characteristics of the cathode (e.g. lithium cobalt oxide) and anode (e.g. graphite). When alternative anode/cathode chemistries are studied the same cut-off voltages are often, mistakenly, used. Silicon (Si) based anodes are widely studied as a high capacity alternative to graphite for Lithium-ion batteries. When silicon-based anodes are paired with high capacity cathodes (e.g. Lithium Nickel Cobalt Aluminium Oxide; NCA) the cell typically suffers from rapid capacity fade. The purpose of this communication is to understand how the choice of upper cut-off voltage affects cell performance in Si/NCA cells. A careful study of three-electrode cell data will show that capacity fade in Si/NCA cells is due to an ever-evolving silicon voltage profile that pushes the upper voltage at the cathode to >4.4 V (vs. Li/Li+). This behaviour initially improves cycle efficiency, due to liberation of new lithium, but ultimately reduces cycling efficiency, resulting in rapid capacity fade.

  18. Electric field and space charge distribution measurement in transformer oil struck by impulsive high voltage

    NASA Astrophysics Data System (ADS)

    Sima, Wenxia; Guo, Hongda; Yang, Qing; Song, He; Yang, Ming; Yu, Fei

    2015-08-01

    Transformer oil is widely used in power systems because of its excellent insulation properties. The accurate measurement of electric field and space charge distribution in transformer oil under high voltage impulse has important theoretical and practical significance, but still remains challenging to date because of its low Kerr constant. In this study, the continuous electric field and space charge distribution over time between parallel-plate electrodes in high-voltage pulsed transformer oil based on the Kerr effect is directly measured using a linear array photoelectrical detector. Experimental results demonstrate the applicability and reliability of this method. This study provides a feasible approach to further study the space charge effects and breakdown mechanisms in transformer oil.

  19. Electroencephalogram measurement using polymer-based dry microneedle electrode

    NASA Astrophysics Data System (ADS)

    Arai, Miyako; Nishinaka, Yuya; Miki, Norihisa

    2015-06-01

    In this paper, we report a successful electroencephalogram (EEG) measurement using polymer-based dry microneedle electrodes. The electrodes consist of needle-shaped substrates of SU-8, a silver film, and a nanoporous parylene protective film. Differently from conventional wet electrodes, microneedle electrodes do not require skin preparation and a conductive gel. SU-8 is superior as a structural material to poly(dimethylsiloxane) (PDMS; Dow Corning Toray Sylgard 184) in terms of hardness, which was used in our previous work, and facilitates the penetration of needles through the stratum corneum. SU-8 microneedles can be successfully inserted into the skin without breaking and could maintain a sufficiently low skin-electrode contact impedance for EEG measurement. The electrodes successfully measured EEG from the frontal pole, and the quality of acquired signals was verified to be as high as those obtained using commercially available wet electrodes without any skin preparation or a conductive gel. The electrodes are readily applicable to record brain activities for a long period with little stress involved in skin preparation to the users.

  20. Spark gap with low breakdown voltage jitter

    DOEpatents

    Rohwein, Gerald J. (Albuquerque, NM); Roose, Lars D. (Albuquerque, NM)

    1996-01-01

    Novel spark gap devices and electrodes are disclosed. The novel spark gap devices and electrodes are suitable for use in a variety of spark gap device applications. The shape of the electrodes gives rise to local field enhancements and reduces breakdown voltage jitter. Breakdown voltage jitter of approximately 5% has been measured in spark gaps according the invention. Novel electrode geometries and materials are disclosed.

  1. Effect on plasma and etch-rate uniformity of controlled phase shift between rf voltages applied to powered electrodes in a triode capacitively coupled plasma reactor

    SciTech Connect

    Sung, Dougyong; Jeong, Sangmin; Park, Youngmin; Volynets, Vladimir N.; Ushakov, Andrey G.; Kim, Gon-Ho

    2009-01-15

    The influence of the phase shift between rf voltages applied to the powered electrodes on plasma parameters and etch characteristics was studied in a very high-frequency (VHF) capacitively coupled plasma (CCP) triode reactor. rf voltages at 100 MHz were simultaneously applied to the top and bottom electrodes having a controlled phase shift between them, which could be varied between 0 deg. and 360 deg. Several plasma and process characteristics were measured as a function of the phase shift: (i) radial profiles of plasma-emission intensity, (ii) line-of-sight averaged plasma-emission intensity, and (iii) radial profiles of blanket SiO{sub 2} etching rate over a 300 mm wafer. Radial profiles of plasma emission were obtained using the scanning optical probe. It has been shown that all the measured characteristics strongly depend on the phase shift: (i) plasma-emission intensity is minimal at phase shift equal to 0 deg. and maximal at 180 deg. for all radial positions, while the emission radial profile changes from bell-shaped distribution with considerable nonuniformity at 0 deg. to a much more flattened distribution at 180 deg.; (ii) line-of-sight averaged plasma-emission intensity shows a similar dependence on the phase shift with minimum and maximum at 0 deg. and 180 deg., respectively; and (iii) the etch-rate radial profile at 180 deg. shows a much better uniformity as compared to that at 0 deg. Some of these results can be qualitatively explained by the redistribution of plasma currents that flow between the electrodes and also from the electrodes to the grounded wall with the phase shift. We suggest that the phase-shift effect can be used to improve the plasma and etch-rate spatial uniformity in VHF-CCP triode reactors.

  2. Apparatus for focused electrode induced polarization logging

    SciTech Connect

    Vinegar, H.J.; Waxman, M.H.

    1986-04-15

    An induced polarization logging tool is described for measuring parameters of a formation surrounding a borehole. The logging tool consists of: a non-conductive logging sonde; a plurality of electrodes disposed on the sonde, the electrodes including at least a survey current electrode and guard electrodes disposed on opposite sides of the survey current electrode, a non-polarizing voltage measuring electrode, a non-polarizing voltage reference electrode and a current return electrode, both the voltage reference and current return electrodes being located a greater distance from the survey current electrode than the guard electrodes; means connected to the survey current electrode and the guard electrodes for generating a signal representative of the potential difference in the formation between the survey current electrode and the guard electrodes; first control means directly coupled to the survey current electrode, the first control means controlling the current flow to the survey current electrode in response to the potential difference signal; a second control means directly coupled to the guard electrodes to control the current flow to the guard electrodes in response to the potential difference signal; a source of alternating current located at the surface, one end of the source being coupled to the two control means and the other to the current return electrode, the source supplying alternating current at various discrete frequencies between substantially 0.01 and 100 Hz; measurement means directly coupled to the voltage measurement and survey current electrodes to measure the amplitude and phase of the voltage induced in the formation and the amplitude and phase of the current flow to the survey electrode; and transmission means for transmitting the measurements to the surface.

  3. Improved electrode paste provides reliable measurement of galvanic skin response

    NASA Technical Reports Server (NTRS)

    Day, J. L.

    1966-01-01

    High-conductivity electrode paste is used in obtaining accurate skin resistance or skin potential measurements. The paste is isotonic to perspiration, is nonirritating and nonsensitizing, and has an extended shelf life.

  4. Electronic transport in oligo-para-phenylene junctions attached to carbon nanotube electrodes: Transition-voltage spectroscopy and chirality

    SciTech Connect

    Brito Silva, C. A. Jr.; Silva, S. J. S. da; Leal, J. F. P.; Pinheiro, F. A.; Del Nero, J.

    2011-06-15

    We have investigated, by means of a nonequilibrium Green's function method coupled to density functional theory, the electronic transport properties of molecular junctions composed of oligo-para-phenylene (with two, three, four, and five phenyl rings) covalently bridging the gap between metallic carbon nanotubes electrodes. We have found that the current is strongly correlated to a purely geometrical chiral parameter, both on-resonance and off-resonance. The Fowler-Nordheim plot exhibits minima, V{sub min}, that occur whenever the tail of a resonant transmission peak enters in the bias window. This result corroborates the scenario in which the coherent transport model gives the correct interpretation to transition voltage spectroscopy (TVS). We have shown that V{sub min} corresponds to voltages where a negative differential resistance (NDR) occurs. The finding that V{sub min} corresponds to voltages that exhibit NDR, which can be explained only in single-molecule junctions within the coherent transport model, further confirms the applicability of such models to adequately interpret TVS. The fact that the electrodes are organic is at the origin of differences in the behavior of V{sub min} if compared to the case of molecular junctions with nonorganic contacts treated so far.

  5. Simple and inexpensive teaching apparatus for absolute measurement of voltage

    NASA Astrophysics Data System (ADS)

    Fulbright, H. W.

    1993-10-01

    Equipment designed for the absolute measurement of voltage is described, suitable for lecture demonstrations or for student laboratory experiments. Although simple and inexpensive it can give results accurate to 1% or 2%. A key element incorporated is a soft drink can.

  6. Primary measurement of total ultrasonic power with improved accuracy in rf voltage measurement

    NASA Astrophysics Data System (ADS)

    Dubey, P. K.; Kumar, Ashok; Kumar, Yudhisther; Gupta, Reeta; Joshi, Deepa

    2010-10-01

    Out of the various existing ultrasonic power measurement techniques, the radiation force balance method using microbalance is most widely used in low power (below 1 W) regime. The major source of uncertainty associated with this technique is the error in ac voltage measurement applied to the transducer for the generation of ultrasonic waves. The sources that deteriorate the ac voltage measurement accuracy include cable length and impedance mismatch. We introduce a new differential peak to peak measurement approach to reduce the ac voltage measurement error. The method holds the average peak amplitude of each polarity. Ultralow offset difference amplifier is used to measure peak to peak voltage. The method is insensitive to the variations in the dc offset of the source. The functionality of this method has been tested and compared with the conventional rf voltage measurement method. The output of this proposed technique is dc, which can be measured with an error of less than 0.1%.

  7. Microfabricated Patch Clamp Electrodes for Improved Ion Channel Protein Measurements

    NASA Astrophysics Data System (ADS)

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

    2002-03-01

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

  8. Means to remove electrode contamination effect of Langmuir probe measurement in space.

    PubMed

    Oyama, K-I; Lee, C H; Fang, H K; Cheng, C Z

    2012-05-01

    Precaution to remove the serious effect of electrode contamination in Langmuir probe experiments has not been taken in many space measurements because the effect is either not understood or ignored. We stress here that one should pay extra attention to the electrode contamination effect to get accurate and reliable plasma measurements so that the long time effort for sounding rocket/satellite missions does not end in vain or becomes less fruitful. In this paper, we describe two main features of voltage-current characteristic curves associated with the contaminated Langmuir probe, which are predicted from the equivalent circuit model, which we proposed in 1970's. We then show that fast sweeping dc Langmuir probes can give reliable results in the steady state regime. The fast sweeping probe can also give reliable results in transient situations such as satellite moves through plasma bubble in the ionosphere where the electron density drastically changes. This fact was first confirmed in our laboratory experiment. PMID:22667663

  9. Means to remove electrode contamination effect of Langmuir probe measurement in space

    SciTech Connect

    Oyama, K.-I.; Lee, C. H.; Fang, H. K.; Cheng, C. Z.

    2012-05-15

    Precaution to remove the serious effect of electrode contamination in Langmuir probe experiments has not been taken in many space measurements because the effect is either not understood or ignored. We stress here that one should pay extra attention to the electrode contamination effect to get accurate and reliable plasma measurements so that the long time effort for sounding rocket/satellite missions does not end in vain or becomes less fruitful. In this paper, we describe two main features of voltage-current characteristic curves associated with the contaminated Langmuir probe, which are predicted from the equivalent circuit model, which we proposed in 1970's. We then show that fast sweeping dc Langmuir probes can give reliable results in the steady state regime. The fast sweeping probe can also give reliable results in transient situations such as satellite moves through plasma bubble in the ionosphere where the electron density drastically changes. This fact was first confirmed in our laboratory experiment.

  10. A two electrode apparatus for electrical impedance measurements

    NASA Astrophysics Data System (ADS)

    Merriam, J. B.

    2009-12-01

    A two electrode cell for complex impedance measurements on core samples in the range 1 mHz - 0.3 kHz is described. Two electrode cells are more convenient than four electrode cells but some restrictions need to be observed. I will show that the contact impedance between the electrodes and the sample can be controlled and reduced to less than fifty ohms in most cases. The contact impedance is repeatable, with a peak phase near 10 Hz of less than one degree and a maximum change in impedance magnitude of less than fifty ohm. A model for the contact impedance is used to correct impedance measurements, leaving an un-modeled contact impedance of a few ohms. There is typically a drift of about 100 ohm during a measurement sequence due to diffusion between the ceramic frits at the ends of the sample. This is corrected by repeat measurements at 100 Hz. Un-modeled impedance changes due to drift are about ten ohm. The un-modeled impedance changes mean that the relative error on conductive samples is greater than on resistive samples. Repeat measurements on a sandstone sample with conductive pore water (0.14 S/m) yield a mean of 492 ohms with a standard deviation of 20 ohm, or about five percent. Measurements on mineralized core and on cells constructed from mixtures of silica sand and polarizable minerals demonstrate that the two electrode set up can be used even on heavily mineralized samples.

  11. Sun photometry using photodiode open circuit voltage measurements

    NASA Astrophysics Data System (ADS)

    Acharya, Y. B.; Jayaraman, A.

    1995-08-01

    A simple technique is explored in which the open circuit voltage of a photodiode is measured using a simple digital multimeter to monitor the solar irradiance and atmospheric optical depths in three spectral bands. The advantage of this technique is that the photometer only consists of an optical interference filter, photodiode, and a measuring digital multimeter, while the electronics circuitry otherwise needed in a conventional photometer is avoided. This makes the system very simple, cost effective, and versatile for even nonprofessionals to handle.

  12. Modeling of gas flow in the cylindrical channels of high-voltage plasma torches with rod electrodes

    NASA Astrophysics Data System (ADS)

    Borovskoy, A. M.; Popov, S. D.; Surov, A. V.

    2013-08-01

    The article is devoted to the calculation of gas dynamic parameters of gas flow in various areas of low-temperature plasma generator, therefore, target area's grid was built for the simulation of plasma gas flow in channels of studied high-voltage AC plasma torches and calculations of three-dimensional gas flow was made using GAMBIT and FLUENT soft-ware and Spalart-Allmares turbulence model, air flow was simulated in the tangential feed's areas, in the cylindrical channel, in the tapering nozzle chamber and in the mixing chamber of plasma torches and outside (in the environment); thus, 3D-modelling of the cold plasma-forming gas flow was performed in cylindrical channels of studied high-voltage AC plasma torches with rod electrodes for the first time.

  13. A high voltage method for measuring low capacitance for tomography.

    PubMed

    Lu, Decai; Shao, Fuqun; Guo, Zhiheng

    2009-05-01

    Low capacitance measurement is involved in many industrial applications, especially in the applications of electrical capacitance tomography (ECT). Most of the low capacitance measurement circuits employ an ac-based method or a charge/discharge method because of high sensitivity, high resolution, and immunity to stray capacitance; and its excitation or charge voltage are not more than 20 V. When ECT techniques for large industrial equipment such as blast furnaces or grain barns are explored, the existing methods for measuring low capacitance have some limitations. This paper proposes a high excitation voltage ac-based method for measuring low capacitance to improve the resolution of measurement. The method uses a high excitation voltage of several hundred volts and a transformer ratio arms as the C/V transducer. Experimental results indicate that the new method has a resolution of 0.005 fF, a good stability (about 0.003 fF over 4 h) and linearity (0.9992). PMID:19485513

  14. Effect of applied voltage, initial concentration and natural organic matter on sequential reduction/oxidation of nitrobenzene by graphite electrodes

    PubMed Central

    Sun, Mei; Reible, Danny D.; Lowry, Gregory V.; Gregory, Kelvin B.

    2012-01-01

    Carbon electrodes are proposed in reactive sediment caps for in situ treatment of contaminants. The electrodes produce reducing conditions and H2 at the cathode and oxidizing conditions and O2 at the anode. Emplaced perpendicular to seepage flow, the electrodes provide the opportunity for sequential reduction and oxidation of contaminants. The objectives of this study are to demonstrate degradation of nitrobenzene (NB) as a probe compound for sequential electrochemical reduction and oxidation, and to determine the effect of applied voltage, initial concentration and natural organic matter on the degradation rate. In H-cell reactors with graphite electrodes and buffer solution, NB was reduced stoichiometrically to aniline (AN) at the cathode with nitrosobenzene (NSB) as the intermediate. AN was then removed at the anode, faster than the reduction step. No common AN oxidation intermediate was detected in the system. Both the first order reduction rate constants of NB (kNB) and NSB (kNSB) increased with applied voltage between 2V and 3.5 V (when the initial NB concentration was 100 µM, kNB=0.3 d?1 and kNSB=0.04 d?1at 2V; kNB=1.6 d?1 and kNSB=0.64 d?1at 3.5 V) but stopped increasing beyond the threshold of 3.5V. When initial NB concentration decreased from 100 to 5 µM, kNB and kNSB became 9 and 5 times faster, respectively, suggesting that competition for active sites on the electrode surface is an important factor in NB degradation. Presence of natural organic matter (in forms of either humic acid or Anacostia River sediment porewater) decreased kNB while slightly increased kNSB, but only to a limited extent (~factor of 3) for dissolved organic carbon content up to 100 mg/l. These findings suggest that electrode-based reactive sediment capping via sequential reduction/oxidation is a potentially robust and tunable technology for in situ contaminants degradation. PMID:22571797

  15. Evaluation of different stimulation and measurement patterns based on internal electrode: application in cardiac impedance tomography.

    PubMed

    Nasehi Tehrani, J; Oh, T I; Jin, C; Thiagalingam, A; McEwan, A

    2012-11-01

    The conductivity distribution around the thorax is altered during the cardiac cycle due to the blood perfusion, heart contraction and lung inflation. Previous studies showed that these bio-impedance changes are appropriate for non-invasive cardiac function imaging using Electrical Impedance Tomography (EIT) techniques. However, the spatial resolution is presently low. One of the main obstacles in cardiac imaging at the heart location is the large impedance variation of the lungs by respiration and muscles on the dorsal and posterior side of the body. In critical care units there is a potential to insert an internal electrode inside the esophagus directly behind the heart in the same plane of the external electrodes. The aim of the present study is to evaluate different current stimulation and measurement patterns with both external and internal electrodes. Analysis is performed with planar arrangement of 16 electrodes for a simulated 3D cylindrical tank and pig thorax model. In our study we evaluated current injection patterns consisting of adjacent, diagonal, trigonometric, and radial to the internal electrode. The performance of these arrangements was assessed using quantitative methods based on distinguishability, sensitivity and GREIT (Graz consensus Reconstruction algorithm for Electrical Impedance Tomography). Our evaluation shows that an internal electrode configuration based on the trigonometric injection patterns has better performance and improves pixel intensity of the small conductivity changes related to heart near 1.7 times in reconstructed images and also shows more stability with different levels of added noise. For the internal electrode, when we combined radial or adjacent injection with trigonometric injection pattern, we found an improvement in amplitude response. However, the combination of diagonal with trigonometric injection pattern deteriorated the shape deformation (correlation coefficient r=0.344) more than combination of radial and trigonometric injection (correlation coefficient r=0.836) for the perturbations in the area close to the center of the cylinder. We also find that trigonometric stimulation pattern performance is degraded in a realistic thorax model with anatomical asymmetry. For that reason we recommend using internal electrodes only for voltage measurements and as a reference electrode during trigonometric stimulation patterns in practical measurements. PMID:23017828

  16. Nanoscopic electrode molecular probes

    DOEpatents

    Krstic, Predrag S. (Knoxville, TN); Meunier, Vincent (Knoxville, TN)

    2012-05-22

    The present invention relates to a method and apparatus for enhancing the electron transport property measurements of a molecule when the molecule is placed between chemically functionalized carbon-based nanoscopic electrodes to which a suitable voltage bias is applied. The invention includes selecting a dopant atom for the nanoscopic electrodes, the dopant atoms being chemically similar to atoms present in the molecule, and functionalizing the outer surface and terminations of the electrodes with the dopant atoms.

  17. Unraveling the voltage fade mechanism in layer Li-Mn-rich electrode: formation of the tetrahedral cations for spinel conversion

    SciTech Connect

    Mohanty, Debasish; Li, Jianlin; Abraham, Daniel P; Huq, Ashfia; Payzant, E Andrew; Wood III, David L; Daniel, Claus

    2014-01-01

    Discovery of high-voltage layered lithium-and manganese-rich (LMR) composite oxide electrode has dramatically enhanced the energy density of current Li-ion energy storage systems. However, practical usage of these materials is currently not viable because of their inability to maintain a consistent voltage profile (voltage fading) during subsequent charge-discharge cycles. This report rationalizes the cause of this voltage fade by providing the evidence of layer to spinel-like (LSL) structural evolution pathways in the host Li1.2Mn0.55Ni0.15Co0.1O2 LMR composite oxide. By employing neutron powder diffraction, and temperature dependent magnetic susceptibility, we show that LSL structural rearrangement in LMR oxide occurs through a tetrahedral cation intermediate via: i) diffusion of lithium atoms from octahedral to tetrahedral sites of the lithium layer [(LiLioct LiLitet] which is followed by the dispersal of the lithium ions from the adjacent octahedral site of the metal layer to the tetrahedral sites of lithium layer [LiTM oct LiLitet]; and ii) migration of Mn from the octahedral sites of the transition metal layer to the permanent octahedral site of lithium layer via tetrahedral site of lithium layer [MnTMoct MnLitet MnLioct)]. The findings opens the door to the potential routes to mitigate this atomic restructuring in the high-voltage LMR composite oxide cathodes by manipulating the composition/structure for practical use in high-energy-density lithium-ion batteries.

  18. Measurement of microchannel fluidic resistance with a standard voltage meter.

    PubMed

    Godwin, Leah A; Deal, Kennon S; Hoepfner, Lauren D; Jackson, Louis A; Easley, Christopher J

    2013-01-01

    A simplified method for measuring the fluidic resistance (R(fluidic)) of microfluidic channels is presented, in which the electrical resistance (R(elec)) of a channel filled with a conductivity standard solution can be measured and directly correlated to R(fluidic) using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine R(fluidic) to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ?40 to 600kPa smm(-3)) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic R(fluidic) measurements were possible in more complex microfluidic designs. Microchannel R(elec) was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems. PMID:23245901

  19. Measurement of Microchannel Fluidic Resistance with a Standard Voltage Meter

    PubMed Central

    Godwin, Leah A.; Deal, Kennon S.; Hoepfner, Lauren D.; Jackson, Louis A.; Easley, Christopher J.

    2012-01-01

    A simplified method for measuring the fluidic resistance (Rfluidic) of microfluidic channels is presented, in which the electrical resistance (Relec) of a channel filled with a conductivity standard solution can be measured and directly correlated to Rfluidic using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine Rfluidic to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ~40 – 600 kPa s mm?3) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic Rfluidic measurements were possible in more complex microfluidic designs. Microchannel Relec was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems. PMID:23245901

  20. Robust signatures in the current-voltage characteristics of DNA molecules oriented between two graphene nanoribbon electrodes

    NASA Astrophysics Data System (ADS)

    Paez, Carlos; Schulz, Peter; Roemer, Rudolf; Wilson, Neil

    2013-03-01

    In this work we numerically calculate the electric current through three kinds of DNA sequences (telomeric, ?-DNA, and p53-DNA) described by different heuristic models. A bias voltage is applied between two zig-zag edged graphene contacts attached to the DNA segments, while a gate terminal modulates the conductance of the molecule. The calculation of current is performed by integrating the transmission function (calculated using the lattice Green's function) over the range of energies allowed by the chemical potentials. We show that a telomeric DNA sequence, when treated as a quantum wire in the fully coherent low-temperature regime, works as an excellent semiconductor. Clear steps are apparent in the current-voltage curves of telomeric sequences and are present independent of lengths and sequence initialisation at the contacts. The current-voltage curves suggest the existence of stepped structures independent of length and sequencing initialisation at the contacts. We also find that the molecule-electrode coupling can drastically influence the magnitude of the current. The difference between telomeric DNA and other DNA, such as ?-DNA and DNA for the tumour suppressor p53, is particularly visible in the length dependence of the current.

  1. Optically-initiated silicon carbide high voltage switch with contoured-profile electrode interfaces

    DOEpatents

    Sullivan, James S.; Hawkins, Steven A.

    2012-09-04

    An improved photoconductive switch having a SiC or other wide band gap substrate material with opposing contoured profile cavities which have a contoured profile selected from one of Rogowski, Bruce, Chang, Harrison, and Ernst profiles, and two electrodes with matching contoured-profile convex interface surfaces.

  2. Battery Impedance Measurement by Laplace Transformation of Charge or Discharge Current/Voltage

    NASA Astrophysics Data System (ADS)

    Nakayama, Masato; Fukuda, Kenichi; Ohmori, Yoshitake; Wakahara, Kenji; Araki, Takuto; Onda, Kazuo

    Impedance spectroscopy of Z(?) is often used in the electrochemical field to analyze electrode reactions and to calculate transient responses. Our previous study measured the overpotential resistance for our thermal behavior model to calculate the temperature rise of Nickel/metal-hydride battery or Lithium-ion battery during charge and discharge cycles. However, the Z(?) measured by AC impedance meter did not agreed with the ones induced by charge/discharge characteristics. Therefore, we focus on the impedance measurement method by Takano et al, who obtained Z(?) for Lithium-ion battery at wide frequency region by the Laplace transformation of both signals of the voltage-step input and its current response. We have extended this method to the Laplace transformation of current-step or current-pulse input signal and its voltage response signal to get Z(?) for any charge/discharge current of Nickel/metal-hydride battery or Lithium-ion battery. We can get almost the same Z(?) by the three different methods, and the measured Z(?) does not depend on both charge/discharge current and the state of charge or the charge input. Moreover, Z(?) including Warlbulg impedance at low frequencies gets near the overpotential resistance that can estimate well the battery temperature rise in our battery thermal behavior model.

  3. Fluctuation-Coupling of Cathode Cavity Pressure and Arc Voltage in a dc Plasma Torch with a Long Inter-Electrode Channel at Reduced Pressure

    NASA Astrophysics Data System (ADS)

    Cao, Jin-Wen; Huang, He-Ji; Pan, Wen-Xia

    2014-11-01

    Fluctuations of cathode cavity pressure and arc voltage are observed experimentally in a dc plasma torch with a long inter-electrode channel. The results show that they have the same frequency of around 4 kHz under typical experimental conditions. The observed phase difference between the pressure and the voltage, which is influenced by the path length between the pressure sensor and the cathode cavity, varies with different input powers. Combined with numerical simulation, the position of the pressure perturbation origin is estimated, and the results show that it is located at 0.01-0.05 m upstream of the inter-electrode channel outlet.

  4. Measurement and Analysis of Gas Bubbles Near a Reference Electrode in Aqueous Solutions

    SciTech Connect

    Supathorn Phongikaroon; Steve Herrmann; Shelly Li; Michael Simpson

    2005-10-01

    Bubble size distributions (BSDs) near a reference electrode (RE) in aqueous glycerol solutions of an electrolyte NaCl have been investigated under various gas superficial velocities (U{sub S}). BSD and voltage reading of the solution were measured by using a high-speed digital camera and a pH/voltage meter, respectively. The results show that bubble size (b) increases with liquid viscosity ({mu}{sub c}) and U{sub S}. Self-similarity is seen and can be described by the log-normal form of the continuous number frequency distribution. The result shows that b controls the voltage reading in each solution. As b increases, the voltage increases because of gas bubbles interrupting their electrolyte paths in the solutions. An analysis of bubble rising velocity reveals that Stokes Law should be used cautiously to describe the system. The fundamental equation for bubble formation was developed via Newton's second law of motion and shown to be the function of three dimensionless groups--Weber number, Bond number, and Capillary number. After linking an electrochemical principle in the practical application, the result indicates that the critical bubble size is {approx}177 {micro}m. Further analysis suggests that there may be 3000 to 70,000 bubbles generated on the anode surface depending on the size of initial bubbles and provides the potential cause of the efficiency drop observed in the practical application.

  5. Continuous phase velocity profile measurement in multiphase flow using a non-invasive multi-electrode electromagnetic flow meter

    NASA Astrophysics Data System (ADS)

    Leeungculsatien, T.; Lucas, G. P.

    2012-03-01

    This paper describes a novel design of electromagnetic flow meter for velocity profile measurement in multiphase flows with non-uniform axial velocity profiles. A Helmholtz coil is used to produce a uniform magnetic field orthogonal to both the flow direction and the plane of an electrode array embedded on the internal surface of a non-conducting pipe wall. Induced voltages acquired from the electrode array are related to the flow velocity distribution via variables known as 'weight values' which are calculated using COMSOL Multiphysics software. Matrix inversion is used to calculate the velocity distribution in the flow cross section from the induced voltages measured at the electrode array. The flow pipe crosssection is divided into a number of pixels and the mean flow velocity of the continuous phase in each of the pixels is calculated from the measured induced voltages. Experimental results are presented for the reconstructed velocity profile of the continuous water phase in an inclined solids-in-water multiphase flow for which the axial water velocity distribution is highly non-uniform. The results presented in this paper are most relevant to flows in which variations in the axial flow velocity occur principally in a single direction.

  6. Pressure-independent point in current-voltage characteristics of coplanar electrode microplasma devices operated in neon

    SciTech Connect

    Meng Lingguo; Lin Zhaojun; Xing Jianping; Liang Zhihu; Liu Chunliang

    2010-05-10

    We introduce the idea of a pressure-independent point (PIP) in a group of current-voltage curves for the coplanar electrode microplasma device (CEMPD) at neon pressures ranging from 15 to 95 kPa. We studied four samples of CEMPDs with different sizes of the microcavity and observed the PIP phenomenon for each sample. The PIP voltage depends on the area of the microcavity and is independent of the height of the microcavity. The PIP discharge current, I{sub PIP}, is proportional to the volume (Vol) of the microcavity and can be expressed by the formula I{sub PIP}=I{sub PIP0}+DxVol. For our samples, I{sub PIP0} (the discharge current when Vol is zero) is about zero and D (discharge current density) is about 3.95 mA mm{sup -3}. The error in D is 0.411 mA mm{sup -3} (less than 11% of D). When the CEMPD operates at V{sub PIP}, the discharge current is quite stable under different neon pressures.

  7. Investigation of low-voltage pulse parameters on electroporation and electrical lysis using a microfluidic device with interdigitated electrodes.

    PubMed

    Morshed, Bashir I; Shams, Maitham; Mussivand, Tofy

    2014-03-01

    Electroporation (EP) of biological cells leads to the exchange of materials through the permeabilized cell membrane, while electrical lysis (EL) irreversibly disrupts the cell membrane. We report a microfluidic device to study these two phenomena with low-voltage excitation for lab-on-a-chip (LOC) applications. For systematic study of EP, we have employed a quantification metric: flow Index (FI) of EP. Simulation and experimental results with the microfluidic device containing interdigitated, coplanar, integrated electrodes to electroporate, and rapidly lyse biological cells are presented. H&E stained human buccal cells were subjected to various pulse magnitudes, pulsewidths, and number of pulses. Simulations show that an electric field of 25 kV/cm with a 20 V applied potential produced 1.3 (°)C temperature rise for a 5 s of excitation. For a 20 V pulse-excitation with pulse-widths between 0.5 to 5 s, EL was observed, whereas for lower excitations, only EP was observed. FI of EP is found to be a direct function of pulse magnitudes, pulsewidths, and numbers of pulses. To release DNA from nucleus, excitation-pulses of 5 s were required. Quantification of EP would be useful for systematic study of EP toward optimization with various excitation pulses, while low-voltage requirement and high yield of EP and EL are critical to develop LOC for drug delivery and cell-sample preparation, respectively. PMID:24557688

  8. Robust signatures in the current-voltage characteristics of DNA molecules oriented between two graphene nanoribbon electrodes

    NASA Astrophysics Data System (ADS)

    Páez, Carlos J.; Schulz, Peter A.; Wilson, Neil R.; Römer, Rudolf A.

    2012-09-01

    In this work, we numerically calculate the electric current through three kinds of DNA sequences (telomeric, ?-DNA and p53-DNA) described by different heuristic models. A bias voltage is applied between two zigzag edged graphene contacts attached to the DNA segments, while a gate terminal modulates the conductance of the molecule. Calculation of the current is performed by integrating the transmission function (calculated using the lattice Green's function) over the range of energies allowed by the chemical potentials. We show that a telomeric DNA sequence, when treated as a quantum wire in the fully coherent low-temperature regime, works as an excellent semiconductor. Clear steps are apparent in the current-voltage curves of telomeric sequences and are present independent of length and sequence initialization at the contacts. We also find that the molecule-electrode coupling can drastically influence the magnitude of the current. The difference between telomeric DNA and other DNAs, such as ?-DNA and DNA for the tumour suppressor p53, is particularly visible in the length dependence of the current.

  9. A microbial fuel cell with the three-dimensional electrode applied an external voltage for synthesis of hydrogen peroxide from organic matter

    NASA Astrophysics Data System (ADS)

    Chen, Jia-yi; Zhao, Lin; Li, Nan; Liu, Hang

    2015-08-01

    The study experimentally investigates the changing performance of three-dimensional electrode H2O2-producting MFCs coupled with simultaneous wastewater treatment at various external cell voltages from 0.1 V to 0.8 V, in order to explore the optimal applied voltage and its reasons. The graphite particle electrodes made of graphite powders with polytetrafluoroethene (PTFE) as the binder are used as three-dimensional cathode. The results indicate that applied voltage is demonstrated to increase the productive rate and output of H2O2 and the efficiency of acetate degradation. Besides, a relatively high current density caused by a high applied voltage has a positive impact on anode performance in terms of organic degradation and coulombic efficiency. In addition, a relatively high voltage leads to the reduction of H2O2 and the evolution of H2. Considering H2O2 concentration, anodic COD removal and current efficiencies of MFCs at various voltages, the optimal voltage is chosen to be 0.4 V, achieving the H2O2 generation of 705.6 mg L-1 at a rate of 2.12 kg m-3 day-1 and 76% COD removal in 8 h, with energy input of 0.659 kWh per kg H2O2. Coulombic efficiency, faradic efficiency and COD conversion efficiency are 92%, 96%, and 88% respectively.

  10. Measuring Mitochondrial Membrane Potential with a Tetraphenylphosphonium-Selective Electrode.

    PubMed

    Moreno, António J; Santos, Dario L; Magalhães-Novais, Sílvia; Oliveira, Paulo J

    2015-01-01

    Mitochondrial bioenergetics is based on the generation of the protonmotive force by the electron transport chain. The protonmotive force is used by mitochondria for different critical aspects of its normal function, ranging from calcium accumulation to the synthesis of ATP. The transmembrane electric potential (??) is the major component of the protonmotive force and is also the main responsible for ATP synthesis by mitochondrial ATP synthase. Although several methods can be used to measure the ??, the use of the tetraphenylphosphonium cation (TPP(+) )-selective electrode is still a method of election due to its sensitivity. The method is based on the accumulation of TPP(+) by energized mitochondria, which develop a negative charge in the matrix due to the ejection of protons. This unit describes how to build a custom-made TPP(+) -selective electrode and how to establish the necessary set-up to follow ?? fluctuations in isolated mitochondrial fractions. © 2015 by John Wiley & Sons, Inc. PMID:26250398

  11. Ultrasound Velocity Measurement in a Liquid Metal Electrode.

    PubMed

    Perez, Adalberto; Kelley, Douglas H

    2015-01-01

    A growing number of electrochemical technologies depend on fluid flow, and often that fluid is opaque. Measuring the flow of an opaque fluid is inherently more difficult than measuring the flow of a transparent fluid, since optical methods are not applicable. Ultrasound can be used to measure the velocity of an opaque fluid, not only at isolated points, but at hundreds or thousands of points arrayed along lines, with good temporal resolution. When applied to a liquid metal electrode, ultrasound velocimetry involves additional challenges: high temperature, chemical activity, and electrical conductivity. Here we describe the experimental apparatus and methods that overcome these challenges and allow the measurement of flow in a liquid metal electrode, as it conducts current, at operating temperature. Temperature is regulated within ±2 °C using a Proportional-Integral-Derivative (PID) controller that powers a custom-built furnace. Chemical activity is managed by choosing vessel materials carefully and enclosing the experimental setup in an argon-filled glovebox. Finally, unintended electrical paths are carefully prevented. An automated system logs control settings and experimental measurements, using hardware trigger signals to synchronize devices. This apparatus and these methods can produce measurements that are impossible with other techniques, and allow optimization and control of electrochemical technologies like liquid metal batteries. PMID:26273726

  12. Design of a micro-interdigitated electrode for impedance measurement performance in a biochemical assay

    E-print Network

    Donoghue, Linda (Linda Marie)

    2011-01-01

    The performance of interdigitated electrodes for impedance measurements is dependent upon the geometric design of the electrode pattern and can be significantly impacted by manufactured variability or defects. For processes ...

  13. An assessment of comparaqtive methods for approaching electrode polarization in dielectric permittivity measurements

    SciTech Connect

    Ben Ishai, Paul; Sobol, Z; Nickels, Jonathan D; Agapov, Alexander L; Sokolov, Alexei P

    2012-01-01

    We examine the validity of three common methods for analysis and correction of the electrode polarization (EP) effect in dielectric spectroscopy measurements of conductive liquid samples. The methods considered are (i) algorithmic treatment by modeling the EP behavior at constant phase angle, (ii) varying the size of the electrode gap, and (iii) polypyrrole (PPyPss) layered electrodes. The latter is a relatively recent innovation suggested to be an efficient solution. We demonstrate that PPyPss coated electrodes do not diminish the effect of EP, and even add relaxation processes of its own. Our conclusion is that these polymer coated electrodes are not suitable for the correction of electrode polarization.

  14. Ionization detector, electrode configuration and single polarity charge detection method

    SciTech Connect

    He, Zhong

    1998-01-01

    An ionization detector, an electrode configuration and a single polarity charge detection method each utilize a boundary electrode which symmetrically surrounds first and second central interlaced and symmetrical electrodes. All of the electrodes are held at a voltage potential of a first polarity type. The first central electrode is held at a higher potential than the second central or boundary electrodes. By forming the first and second central electrodes in a substantially interlaced and symmetrical pattern and forming the boundary electrode symmetrically about the first and second central electrodes, signals generated by charge carriers are substantially of equal strength with respect to both of the central electrodes. The only significant difference in measured signal strength occurs when the charge carriers move to within close proximity of the first central electrode and are received at the first central electrode. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge.

  15. Ionization detector, electrode configuration and single polarity charge detection method

    DOEpatents

    He, Z.

    1998-07-07

    An ionization detector, an electrode configuration and a single polarity charge detection method each utilize a boundary electrode which symmetrically surrounds first and second central interlaced and symmetrical electrodes. All of the electrodes are held at a voltage potential of a first polarity type. The first central electrode is held at a higher potential than the second central or boundary electrodes. By forming the first and second central electrodes in a substantially interlaced and symmetrical pattern and forming the boundary electrode symmetrically about the first and second central electrodes, signals generated by charge carriers are substantially of equal strength with respect to both of the central electrodes. The only significant difference in measured signal strength occurs when the charge carriers move to within close proximity of the first central electrode and are received at the first central electrode. The measured signals are then subtracted and compared to quantitatively measure the magnitude of the charge. 10 figs.

  16. Electrode measurements of the net charge on muscle proteins

    NASA Astrophysics Data System (ADS)

    Bryson, Elzbieta Anna

    1997-12-01

    Electrode techniques for measuring Donnan potentials in protein solutions were studied and applied to elucidate the effect of methylation on the net charge of heavy meromyosin (HMM) and the effect of Ca2+ on the net charge of the thin filament proteins. Drifts in potentials, observed for macroelectrodes, were examined and their cause established to be KCl leakage out of electrodes. The microelectrode technique was applied to protein solutions and microelectrodes with resistance less than 1 M? were used: the conditions for manufacturing and maintaining electrodes functional were established. HMM was isolated (from rabbit muscle) and methylated; the modification was verified by amino acid analysis. ATPase activity of methylated HMM was found to be significantly elevated in the presence of Ca2+ and decreased in the presence of EDTA with respect to the activity of the native protein. Values of the net charge of both proteins were determined at pH 6.7 and no significant difference was found between them. Calculations of the theoretical charge of lysine and N?-dimethyllysine were performed which indicated only 0.5% difference at pH 6.7. F-actin, tropomyosin-troponin (Tm-tn) and reconstituted thin filaments (RTFs) were isolated from rabbit muscle. Conditions for preserving the binding between F-actin and Tm-tn were established. Net charges of F-actin, Tm-tn, RTFs and BSA (control) were measured in solutions of pCa 3.2-8.7 at ionic strength 0.02 M and pH 7.0. Significant decrease in the negative charge of the RTFs, Tm-tn and F- actin was observed with increasing concentrations of free Ca2+, between pCa 6.5 and 3 approximately. Values of the molecular and specific charge at pH 7.0 and the isoelectric point were calculated from the amino acid sequences of the main muscle proteins.

  17. Laser interferometric measurement of ion electrode shape and charge exchange erosion

    NASA Technical Reports Server (NTRS)

    Macrae, Gregory S.; Mercer, Carolyn R.

    1991-01-01

    A projected fringe profilometry system was applied to surface contour measurements of an accelerator electrode from an ion thrustor. The system permitted noncontact, nondestructive evaluation of the fine and gross structure of the electrode. A 3-D surface map of a dished electrode was generated without altering the electrode surface. The same system was used to examine charge exchange erosion pits near the periphery of the electrode to determine the depth, location, and volume of material lost. This electro-optical measurement system allowed rapid, nondestructive, digital data acquisition coupled with automated computer data processing. In addition, variable sensitivity allowed both coarse and fine measurements of objects having various surface finishes.

  18. Membrane reference electrode

    DOEpatents

    Redey, L.; Bloom, I.D.

    1988-01-21

    A reference electrode utilizes a small thin, flat membrane of a highly conductive glass placed on a small diameter insulator tube having a reference material inside in contact with an internal voltage lead. When the sensor is placed in a non-aqueous ionic electrolytic solution, the concentration difference across the glass membrane generates a low voltage signal in precise relationship to the concentration of the species to be measured, with high spatial resolution. 2 figs.

  19. Single Cell Measurement of Dopamine Release with Simultaneous Voltage-clamp and Amperometry

    PubMed Central

    Saha, Kaustuv; Swant, Jarod; Khoshbouei, Habibeh

    2012-01-01

    After its release into the synaptic cleft, dopamine exerts its biological properties via its pre- and post-synaptic targets1. The dopamine signal is terminated by diffusion2-3, extracellular enzymes4, and membrane transporters5. The dopamine transporter, located in the peri-synaptic cleft of dopamine neurons clears the released amines through an inward dopamine flux (uptake). The dopamine transporter can also work in reverse direction to release amines from inside to outside in a process called outward transport or efflux of dopamine5. More than 20 years ago Sulzer et al. reported the dopamine transporter can operate in two modes of activity: forward (uptake) and reverse (efflux)5. The neurotransmitter released via efflux through the transporter can move a large amount of dopamine to the extracellular space, and has been shown to play a major regulatory role in extracellular dopamine homeostasis6. Here we describe how simultaneous patch clamp and amperometry recording can be used to measure released dopamine via the efflux mechanism with millisecond time resolution when the membrane potential is controlled. For this, whole-cell current and oxidative (amperometric) signals are measured simultaneously using an Axopatch 200B amplifier (Molecular Devices, with a low-pass Bessel filter set at 1,000 Hz for whole-cell current recording). For amperometry recording a carbon fiber electrode is connected to a second amplifier (Axopatch 200B) and is placed adjacent to the plasma membrane and held at +700 mV. The whole-cell and oxidative (amperometric) currents can be recorded and the current-voltage relationship can be generated using a voltage step protocol. Unlike the usual amperometric calibration, which requires conversion to concentration, the current is reported directly without considering the effective volume7. Thus, the resulting data represent a lower limit to dopamine efflux because some transmitter is lost to the bulk solution. PMID:23207721

  20. Improved open-circuit voltage in Cu(In,Ga)Se{sub 2} solar cells with high work function transparent electrodes

    SciTech Connect

    Jäger, Timo Romanyuk, Yaroslav E.; Bissig, Benjamin; Pianezzi, Fabian; Nishiwaki, Shiro; Reinhard, Patrick; Steinhauser, Jérôme; Tiwari, Ayodhya N.; Schwenk, Johannes

    2015-06-14

    Hydrogenated indium oxide (IOH) is implemented as transparent front contact in Cu(In,Ga)Se{sub 2} (CIGS) solar cells, leading to an open circuit voltage V{sub OC} enhanced by ?20?mV as compared to reference devices with ZnO:Al (AZO) electrodes. This effect is reproducible in a wide range of contact sheet resistances corresponding to various IOH thicknesses. We present the detailed electrical characterization of glass/Mo/CIGS/CdS/intrinsic ZnO (i-ZnO)/transparent conductive oxide (TCO) with different IOH/AZO ratios in the front TCO contact in order to identify possible reasons for the enhanced V{sub OC}. Temperature and illumination intensity-dependent current-voltage measurements indicate that the dominant recombination path does not change when AZO is replaced by IOH, and it is mainly limited to recombination in the space charge region and at the junction interface of the solar cell. The main finding is that the introduction of even a 5?nm-thin IOH layer at the i-ZnO/TCO interface already results in a step-like increase in V{sub OC}. Two possible explanations are proposed and verified by one-dimensional simulations using the SCAPS software. First, a higher work function of IOH as compared to AZO is simulated to yield an V{sub OC} increase by 21?mV. Second, a lower defect density in the i-ZnO layer as a result of the reduced sputter damage during milder sputter-deposition of IOH can also add to a maximum enhanced V{sub OC} of 25?mV. Our results demonstrate that the proper choice of the front TCO contact can reduce the parasitic recombination and boost the efficiency of CIGS cells with improved corrosion stability.

  1. Measuring Vitamin C Content of Commercial Orange Juice Using a Pencil Lead Electrode

    ERIC Educational Resources Information Center

    King, David; Friend, Jeffrey; Kariuki, James

    2010-01-01

    A pencil lead successfully served as an electrode for the determination of ascorbic acid in commercial orange juice. Cyclic voltammetry was used as an electrochemical probe to measure the current produced from the oxidation of ascorbic acid with a variety of electrodes. The data demonstrate that the less expensive pencil lead electrode gives…

  2. Module Four: Measuring Current and Voltage in Series Circuits; Basic Electricity and Electronics Individualized Learning System.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    The module covers the characteristics of series circuits, how to use the multimeter as an ammeter and voltmeter, and how to make current and voltage measurements in series circuits. This module is divided into three lessons: measuring current in a series circuit, voltage in a series circuit, and using the multimeter as a voltmeter. Each lesson…

  3. Measurements of the volt-ampere characteristics and the breakdown voltages of direct-current helium and hydrogen discharges in microgaps

    SciTech Connect

    Klas, M.; Matej?ik, Š.; Radjenovi?, B.; Radmilovi?-Radjenovi?, M.

    2014-10-15

    The discharge phenomena for micro meter gap sizes include many interesting problems from engineering and physical perspectives. In this paper, the authors deal with the experimental and theoretical results of the breakdown voltage and current-voltage characteristics of the direct-current helium and hydrogen discharges. The measurements were performed at a constant pressure of around one atmosphere, while varying the gap size between two parallel plane tungsten electrodes between 1??m and 100??m. From the measured breakdown voltage curves, the effective yields and the ionization coefficients were derived for both gases. Present data for the ionization coefficients correlate with the data obtained for the breakdown voltage curves measured for fixed 100??m interelectrode separation. The current-voltage characteristics were plotted for the various gap sizes illustrating the role of the field emission effects in the microgaps. Based on the Fowler-Nordheim theory, the enhancement factors were determined. The gap spacing dependence of the field emission current can be explained by the introduction of two ideas, the first being a space charge effect by emitted electrons, and the second a change in the breakdown mechanism. Experimental results, presented here, demonstrate that Townsend phenomenology breaks down when field emission becomes the key mechanism affecting the breakdown and deforming the left hand side of the breakdown voltage curves.

  4. Voltage Clamp Fluorometric Measurements on a Type II Na+-coupled Pi Cotransporter: Shedding Light on Substrate Binding Order

    PubMed Central

    Virkki, Leila V.; Murer, Heini; Forster, Ian C.

    2006-01-01

    Voltage clamp fluorometry (VCF) combines conventional two-electrode voltage clamp with fluorescence measurements to detect protein conformational changes, as sensed by a fluorophore covalently attached to the protein. We have applied VCF to a type IIb Na+-coupled phosphate cotransporter (NaPi-IIb), in which a novel cysteine was introduced in the putative third extracellular loop and expressed in Xenopus oocytes. Labeling this cysteine (S448C) with methanethiosulfonate (MTS) reagents blocked cotransport function, however previous electrophysiological studies (Lambert G., I.C. Forster, G. Stange, J. Biber, and H. Murer. 1999. J. Gen. Physiol. 114:637–651) suggest that substrate interactions with the protein can still occur, thus permitting study of a limited subset of states. After labeling S448C with the fluorophore tetramethylrhodamine MTS, we detected voltage- and substrate-dependent changes in fluorescence (?F), which suggested that this site lies in an environment that is affected by conformational change in the protein. ?F was substrate dependent (no ?F was detectable in 0 mM Na+) and showed little correlation with presteady-state charge movements, indicating that the two signals provide insight into different underlying physical processes. Interpretation of ion substitution experiments indicated that the substrate binding order differs from our previous model (Forster, I., N. Hernando, J. Biber, and H. Murer. 1998. J. Gen. Physiol. 112:1–18). In the new model, two (rather than one) Na+ ions precede Pi binding, and only the second Na+ binding transition is voltage dependent. Moreover, we show that Li+, which does not drive cotransport, interacts with the first Na+ binding transition. The results were incorporated in a new model of the transport cycle of type II Na+/Pi cotransporters, the validity of which is supported by simulations that successfully predict the voltage and substrate dependency of the experimentally determined fluorescence changes. PMID:16636203

  5. Time-resolved voltage measurements of Z-pinch radiation sources with a vacuum voltmeter.

    PubMed

    Murphy, D P; Allen, R J; Weber, B V; Commisso, R J; Apruzese, J P; Phipps, D G; Mosher, D

    2008-10-01

    A vacuum-voltmeter (VVM) was fielded on the Saturn pulsed power generator during a series of argon gas-puff Z-pinch shots. Time-resolved voltage and separately measured load current are used to determine several dynamic properties as the load implodes, namely, the inductance, L(t), net energy coupled to the load, E(coupled)(t), and the load radius, r(t). The VVM is a two-stage voltage divider, designed to operate at voltages up to 2 MV. The VVM is presently being modified to operate at voltages up to 6 MV for eventual use on the Z generator. PMID:19044468

  6. Electrochemical cell and electrode designs for high-temperature/high-pressure kinetic measurements

    SciTech Connect

    Nagy, Z.; Yonco, R.M.

    1987-05-01

    Many corrosion processes of interest to the nuclear power industry occur in high-temperature/high-pressure aqueous systems. The investigation of the kinetics of the appropriate electrode reactions is a serious experimental challenge, partially because of the high temperatures and pressures and partially because many of these reactions are very rapid, requiring fast relaxation measurements. An electrochemical measuring system is described which is suitable for measurements of the kinetics of fast electrode reactions at temperatures extending to at least 300C and pressures to at least 10 MPa (100 atmospheres). The system includes solution preparation and handling equipment, the electrochemical cell, and several electrode designs. One of the new designs is a coaxial working electrode-counter electrode assembly; this electrode can be used with very fast-rising pulses, and it provides a well defined, repeatedly-polishable working surface. Low-impedance reference electrodes are also described, based on electrode concepts responding to the pH or the redox potential of the test solution. Additionally, a novel, long-life primary reference electrode design is reported, based on a modification of the external, pressure-balanced Ag/AgCl reference electrode.

  7. Measurement of effective piezoelectric coefficients of PZT thin films for energy harvesting application with interdigitated electrodes.

    PubMed

    Chidambaram, Nachiappan; Mazzalai, Andrea; Muralt, Paul

    2012-08-01

    Interdigitated electrode (IDE) systems with lead zirconate titanate (PZT) thin films play an increasingly important role for two reasons: first, such a configuration generates higher voltages than parallel plate capacitor-type electrode (PPE) structures, and second, the application of an electric field leads to a compressive stress component in addition to the overall stress state, unlike a PPE structure, which results in tensile stress component. Because ceramics tend to crack at relatively moderate tensile stresses, this means that IDEs have a lower risk of cracking than PPEs. For these reasons, IDE systems are ideal for energy harvesting of vibration energy, and for actuators. Systematic investigations of PZT films with IDE systems have not yet been undertaken. In this work, we present results on the evaluation of the in-plane piezoelectric coefficients with IDE systems. Additionally, we also propose a simple and measurable figure of merit (FOM) to analyze and evaluate the relevant piezoelectric parameter for harvesting efficiency without the need to fabricate the energy harvesting device. Idealized effective coefficients e(IDE) and h(IDE) are derived, showing its composite nature with about one-third contribution of the transverse effect, and about two-thirds contribution of the longitudinal effect in the case of a PZT film deposited on a (100)-oriented silicon wafer with the in-plane electric field along one of the <011> Si directions. Randomly oriented 1-?m-thick PZT 53/47 film deposited by a sol-gel technique, was evaluated and yielded an effective coefficient e(IDE) of 15 C·m(-2). Our FOM is the product between effective e and h coefficient representing twice the electrical energy density stored in the piezoelectric film per unit strain deformation (both for IDE and PPE systems). Assuming homogeneous fields between the fingers, and neglecting the contribution from below the electrode fingers, the FOM for IDE structures with larger electrode gap is derived to be twice as large as for PPE structures, for PZT-5H properties. The experiments yielded an FOM of the IDE structures of 1.25 × 10(10) J/m(3) and 14 mV/? strain. PMID:22899110

  8. Determination of the inductance of imploding wire array Z-pinches using measurements of load voltage

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Hall, G. N.; Harvey-Thompson, A. J.; Suzuki-Vidal, F.; Swadling, G. F.; Khoory, E.; Pickworth, L.; Bland, S. N.; Grouchy, P. de; Skidmore, J.

    2013-03-15

    The inductance of imploding cylindrical wire array z-pinches has been determined from measurements of load voltage and current. A thorough analysis method is presented that explains how the load voltage of interest is found from raw signals obtained using a resistive voltage divider. This method is applied to voltage data obtained during z-pinch experiments carried out on the MAGPIE facility (1.4 MA, 240 ns rise-time) in order to calculate the load inductance and thereafter the radial trajectory of the effective current sheath during the snowplough implosion. Voltage and current are monitored very close to the load, allowing these calculations to be carried out without the need for circuit modelling. Measurements give a convergence ratio for the current of between 3.1 and 5.7 at stagnation of the pinch.

  9. Generation of large-scale, barrier-free diffuse plasmas in air at atmospheric pressure using array wire electrodes and nanosecond high-voltage pulses

    SciTech Connect

    Teng, Yun; Li, Lee Liu, Yun-Long; Liu, Lun; Liu, Minghai

    2014-10-15

    This paper introduces a method to generate large-scale diffuse plasmas by using a repetition nanosecond pulse generator and a parallel array wire-electrode configuration. We investigated barrier-free diffuse plasmas produced in the open air in parallel and cross-parallel array line-line electrode configurations. We found that, when the distance between the wire-electrode pair is small, the discharges were almost extinguished. Also, glow-like diffuse plasmas with little discharge weakening were obtained in an appropriate range of line-line distances and with a cathode-grounding cross-electrode configuration. As an example, we produced a large-scale, stable diffuse plasma with volumes as large as 18?×?15?×?15?cm{sup 3}, and this discharge region can be further expanded. Additionally, using optical and electrical measurements, we showed that the electron temperature was higher than the gas temperature, which was almost the same as room temperature. Also, an array of electrode configuration with more wire electrodes had helped to prevent the transition from diffuse discharge to arc discharge. Comparing the current waveforms of configurations with 1 cell and 9 cells, we found that adding cells significantly increased the conduction current and the electrical energy delivered in the electrode gaps.

  10. Titanium Dioxide Nanoparticle-Based Interdigitated Electrodes: A Novel Current to Voltage DNA Biosensor Recognizes E. coli O157:H7

    PubMed Central

    Nadzirah, Sh.; Azizah, N.; Hashim, Uda; Gopinath, Subash C. B.; Kashif, Mohd

    2015-01-01

    Nanoparticle-mediated bio-sensing promoted the development of novel sensors in the front of medical diagnosis. In the present study, we have generated and examined the potential of titanium dioxide (TiO2) crystalline nanoparticles with aluminium interdigitated electrode biosensor to specifically detect single-stranded E.coli O157:H7 DNA. The performance of this novel DNA biosensor was measured the electrical current response using a picoammeter. The sensor surface was chemically functionalized with (3-aminopropyl) triethoxysilane (APTES) to provide contact between the organic and inorganic surfaces of a single-stranded DNA probe and TiO2 nanoparticles while maintaining the sensing system’s physical characteristics. The complement of the target DNA of E. coli O157:H7 to the carboxylate-probe DNA could be translated into electrical signals and confirmed by the increased conductivity in the current-to-voltage curves. The specificity experiments indicate that the biosensor can discriminate between the complementary sequences from the base-mismatched and the non-complementary sequences. After duplex formation, the complementary target sequence can be quantified over a wide range with a detection limit of 1.0 x 10-13M. With target DNA from the lysed E. coli O157:H7, we could attain similar sensitivity. Stability of DNA immobilized surface was calculated with the relative standard deviation (4.6%), displayed the retaining with 99% of its original response current until 6 months. This high-performance interdigitated DNA biosensor with high sensitivity, stability and non-fouling on a novel sensing platform is suitable for a wide range of biomolecular interactive analyses. PMID:26445455

  11. Improving the measurement accuracy of mixed gas by optimizing carbon nanotube sensor's electrode separation

    NASA Astrophysics Data System (ADS)

    Hao, Huimin; Zhang, Yong; Quan, Long

    2015-10-01

    Because of excellent superiorities, triple-electrode carbon nanotube sensor acts good in the detection of multi-component mixed gas. However, as one of the key factors affecting the accuracy of detection, the electrode separation of carbon nanotube gas sensor with triple-electrode structure is very difficult to decide. An optimization method is presented here to improve the mixed gas measurement accuracy. This method optimizes every separation between three electrodes of the carbon nanotube sensors in the sensor array when test the multi-component gas mixture. It collects the ionic current detected by sensor array composed of carbon nanotube sensors with different electrode separations, and creates the kernel partial least square regression (KPLSR) quantitative analysis model of detected gases. The optimum electrode separations come out when the root mean square error of prediction (RMSEP) of test samples reaches the minimum value. The gas mixtures of CO and NO2 are measured using sensor array composed of two carbon nanotube sensor with different electrode separations. And every electrode separation of two sensors is optimized by above-mentioned method. The experimental results show that the proposed method selects the optimal distances between electrodes effectively, and achieves higher measurement accuracy.

  12. Heterogeneously integrated impedance measuring system with disposable thin-film electrodes

    E-print Network

    Ma, Hanbin; Li, Jiahao; Cheng, Xiang; Nathan, Arokia

    2015-01-28

    on the electrode design. For DNA concentration measurement, this system enables a doubled sensitivity measurement over the previous work. Acknowledgements This work is partially supported by Isaac Newton Trust. Reference [1] N. Sui, L. Wang, T. Yan, F. Liu...

  13. High voltage coaxial switch

    DOEpatents

    Rink, J.P.

    1983-07-19

    A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure. 3 figs.

  14. High voltage coaxial switch

    DOEpatents

    Rink, John P. (Los Alamos, NM)

    1983-07-19

    A coaxial high voltage, high current switch having a solid cylindrical cold cathode coaxially surrounded by a thin hollow cylindrical inner electrode and a larger hollow cylindrical outer electrode. A high voltage trigger between the cathode and the inner electrode causes electrons to be emitted from the cathode and flow to the inner electrode preferably through a vacuum. Some of the electrons penetrate the inner electrode and cause a volumetric discharge in the gas (which may be merely air) between the inner and outer electrodes. The discharge provides a low impedance path between a high voltage charge placed on the outer electrode and a load (which may be a high power laser) coupled to the inner electrode. For high repetition rate the gas between the inner and outer electrodes may be continuously exchanged or refreshed under pressure.

  15. Measuring the impedance of the active electrode of a single channel cochlear implant in situ.

    PubMed

    Hrubý, J; Klier, E; Picka, J; Sedlák, S; Betka, J; Valvoda, M

    1988-10-01

    A number of failures of extracochlear implants are caused by a bad contact between the active electrode and the tissue. A novel and simple method has been developed to enable the impedance of the active electrode to be measured before completion of surgery. PMID:3236876

  16. A Method for Measuring Voltage-Dependent Capacitance Using TDR System

    NASA Astrophysics Data System (ADS)

    Ariga, Zen-Nosuke; Wada, Keiji; Shimizu, Toshihisa

    The measurement of circuit parasitic parameters and evaluation of equivalent circuit models are necessary for a noise analysis or a high-speed operation circuit design of power electronics circuits. Recently, time domain reflectmetry (TDR) has emerged as a technique for measuring circuit parameters. This paper proposes a TDR method for measuring the voltage-dependent capacitance of a power MOSFET. This method can be used to measure the output capacitance Coss of a MOSFET for any DC bias voltage. The Coss of a MOSFET with VDS=350 V was measured in an experiment, while the datasheet gives values of Coss only for V DS values in the range 35-100 V.

  17. Effects of Impulse Voltage Polarity, Peak Amplitude, and Rise Time on Streamers Initiated From a Needle Electrode in Transformer Oil

    E-print Network

    Jadidian, Jouya

    An electrothermal hydrodynamic model is presented to evaluate effects of the applied lightning impulse voltage parameters such as polarity, magnitude, and rise time on the initiation and propagation of the streamers formed ...

  18. Relationship between Work Function of Hole Collection Electrode and Temperature Dependence of Open-Circuit Voltage in Multilayered Organic Solar Cells

    NASA Astrophysics Data System (ADS)

    Itoh, Eiji; Shirotori, Toshiki

    2012-02-01

    We have investigated the photovoltaic properties of multilayered organic photovoltaic devices consisting of indium tin oxide (ITO)/(NiO)/donor/C60/bathocuproine (BCP)/Al structures. Open circuit voltage (VOC) increases with the decrease in temperature between 40 and 350 K. The VOC was, however, pinned at approximately 0.6 V for the device without NiO, probably owing to the insufficient work-function difference between ITO and Al electrodes. The hole injection was also markedly suppressed at the ITO/donor interface in the device with large IP donor materials without the buffer layer and abnormal S-shaped current density-voltage (J-V) characteristics were observed. On the other hand, the value of VOC increases with the increase in ionization potential (IP) of donor materials in the device with NiO buffer layers owing to the enhanced work-function difference of about 1 eV, and the S-shaped curves disappeared at the high temperatures above 200 K. The VOC is further improved to nearly 1.2 V by the UV-ozone treatment of the NiO surface. We have therefore concluded that the increment of work function of the anode caused by the insertion of an oxide buffer layer and the surface treatment of the electrode by UV-ozone treatment are essentially important for the improvement of VOC and charge transport/injection properties in the multilayered organic solar cell applications.

  19. Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements

    NASA Astrophysics Data System (ADS)

    Reinelt, J.; Westermeier, M.; Ruhrmann, C.; Bergner, A.; Awakowicz, P.; Mentel, J.

    2011-03-01

    Phase-resolved temperature distributions are determined along a rod-shaped tungsten electrode, by which an ac arc is operated within a model lamp filled with argon. Switched dc and sinusoidal currents are applied with amplitudes of several amperes and operating frequencies being varied between 10 Hz and 10 kHz. The temperature is deduced from the grey body radiation of the electrode being recorded with a spectroscopic measuring system. Phase-resolved values of the electrode tip temperature Ttip and of the power input Pin are determined comparing the measured temperature distributions with the integral of the one-dimensional heat balance with these parameters as integration constants. They are supplemented by phase-resolved measurements of the sum of cathode and anode fall called the electrode sheath voltage. If a switched dc current is applied it is found that both quantities are within the cathodic phase only marginally higher than for a cathode being operated with a dc current. Ttip and Pin start to decrease for low currents and to increase for high currents at the beginning of the anodic phase. But with increasing operating frequency the deviations from the cathodic phase are reduced until they cannot be resolved for frequencies of several kHz. A more pronounced modulation, but the same tendencies, is observed with a sinusoidal current waveform. For 10 kHz a diffuse arc attachment with an almost phase-independent electrode tip temperature, which deviates only marginally from that of a dc cathode, and an electrode sheath voltage proportional to the arc current is established with both current waveforms.

  20. Comparison of dry-textile electrodes for electrical bioimpedance spectroscopy measurements

    NASA Astrophysics Data System (ADS)

    Márquez, J. C.; Seoane, F.; Välimäki, E.; Lindecrantz, K.

    2010-04-01

    Textile Electrodes have been widely studied for biopotentials recordings, specially for monitoring the cardiac activity. Commercially available applications, such as Adistar T-shirt and Textronics Cardioshirt, have proved a good performance for heart rate monitoring and are available worldwide. Textile technology can also be used for Electrical Bioimpedance Spectroscopy measurements enabling home and personalized health monitoring applications however solid ground research about the measurement performance of the electrodes must be done prior to the development of any textile-enabled EBI application. In this work a comparison of the measurement performance of two different types of dry-textile electrodes and manufacturers has been performed against standardized RedDot 3M Ag/AgCl electrolytic electrodes. 4-Electrode, whole body, Ankle-to-Wrist EBI measurements have been taken with the Impedimed spectrometer SFB7 from healthy subjects in the frequency range of 3kHz to 500kHz. Measurements have been taken with dry electrodes at different times to study the influence of the interaction skin-electrode interface on the EBI measurements. The analysis of the obtained complex EBI spectra shows that the measurements performed with textile electrodes produce constant and reliable EBI spectra. Certain deviation can be observed at higher frequencies and the measurements obtained with Textronics and Ag/AgCl electrodes present a better resemblance. Textile technology, if successfully integrated it, may enable the performance of EBI measurements in new scenarios allowing the rising of novel wearable monitoring applications for home and personal care as well as car safety.

  1. Convenient Fabrication of Fine Electrodes for Electric Measurement of Nanofibers by Nanoimprint Lithography

    NASA Astrophysics Data System (ADS)

    Iwai, Hisanao; Yoshida, Ken-ich; Heike, Seiji; Hashizume, Tomihiro; Shimomura, Takeshi

    2012-03-01

    We fabricated fine electrodes conventionally by nanoimprint lithography (NIL) to measure the electric properties of nanofibers and showed the performance of fine electrodes by the field-effect transistor (FET) measurement of a semiconducting polymer nanofiber. Furthermore, we performed the FET measurement of regioregular poly(3-hexylthiophene-2,5-diyl) (rr-P3HT) nanofibers using fabricated fine electrodes. As a result, the mobility was estimated to be 1.32×10-3 cm2 V-1 s-1, which was on the same order as that reported previously. The fabrication method was clarified to be effective for molecular electronics.

  2. Stark broadening measurement of the electron density in an atmospheric pressure argon plasma jet with double-power electrodes

    SciTech Connect

    Qian Muyang; Ren Chunsheng; Wang Dezhen; Zhang Jialiang; Wei Guodong

    2010-03-15

    Characteristics of a double-power electrode dielectric barrier discharge of an argon plasma jet generated at the atmospheric pressure are investigated in this paper. Time-averaged optical emission spectroscopy is used to measure the plasma parameters, of which the excitation electron temperature is determined by the Boltzmann's plot method whereas the gas temperature is estimated using a fiber thermometer. Furthermore, the Stark broadening of the hydrogen Balmer H{sub {beta}} line is applied to measure the electron density, and the simultaneous presence of comparable Doppler, van der Waals, and instrumental broadenings is discussed. Besides, properties of the jet discharge are also studied by electrical diagnosis. It has been found that the electron densities in this argon plasma jet are on the order of 10{sup 14} cm{sup -3}, and the excitation temperature, gas temperature, and electron density increase with the applied voltage. On the other hand, these parameters are inversely proportional to the argon gas flow rate.

  3. Development of Low-Frequency AC Voltage Measurement System Using Single-Junction Thermal Converter

    NASA Astrophysics Data System (ADS)

    Amagai, Yasutaka; Nakamura, Yasuhiro

    Accurate measurement of low-frequency AC voltage using a digital multimeter at frequencies of 4-200Hz is a challenge in the mechanical engineering industry. At the National Metrology Institute of Japan, we developed a low-frequency AC voltage measurement system for calibrating digital multimeters operating at frequencies down to 1 Hz. The system uses a single-junction thermal converter and employs a theoretical model and a three-parameter sine wave fitting algorithm based on the least-square (LS) method. We calibrated the AC voltage down to 1Hz using our measurement system and reduced the measurement time compared with that using thin-film thermal converters. Our measurement results are verified by comparison with those of a digital sampling method using a high-resolution analog-to-digital converter; our data are in agreement to within a few parts in 105. Our proposed method enables us to measure AC voltage with an uncertainty of 25 ?V/V (k = 1) at frequencies down to 4 Hz and a voltage of 10 V.

  4. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, George J. (Livermore, CA); Sampayan, Stephen E. (Manteca, CA); Kirbie, Hugh C. (Dublin, CA)

    1998-01-01

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface.

  5. Dielectric-wall linear accelerator with a high voltage fast rise time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators

    DOEpatents

    Caporaso, G.J.; Sampayan, S.E.; Kirbie, H.C.

    1998-10-13

    A dielectric-wall linear accelerator is improved by a high-voltage, fast rise-time switch that includes a pair of electrodes between which are laminated alternating layers of isolated conductors and insulators. A high voltage is placed between the electrodes sufficient to stress the voltage breakdown of the insulator on command. A light trigger, such as a laser, is focused along at least one line along the edge surface of the laminated alternating layers of isolated conductors and insulators extending between the electrodes. The laser is energized to initiate a surface breakdown by a fluence of photons, thus causing the electrical switch to close very promptly. Such insulators and lasers are incorporated in a dielectric wall linear accelerator with Blumlein modules, and phasing is controlled by adjusting the length of fiber optic cables that carry the laser light to the insulator surface. 12 figs.

  6. Electrode-Skin contact impedance: In vivo measurements on an ovine model

    NASA Astrophysics Data System (ADS)

    Nguyen, D. T.; Kosobrodov, R.; Barry, M. A.; Chik, W.; Jin, C.; Oh, T. I.; Thiagalingam, A.; McEwan, A.

    2013-04-01

    The problem of electrical impedance between the skin and the electrode is an on-going challenge in bio-electronics. This is particularly true in the case of Electrical Impedance Tomography (EIT), which uses a large number of skin-contact electrodes and is very sensitive to noise. In the present article, contact impedance is measured and compared for a range of electrodes placed on the thorax of an ovine model. The study has been approved by the Westmead Hospital Animal Ethics Committee. The electrode models that were employed in the research are Ag/AgCl electrodes (E1), commonly used for ECG and EIT measurements in both humans and animal models, stainless steel crocodile clips (E2), typically used on animal models, and novel multi-point dry electrodes in two modifications: bronze plated (E3) and nickel plated (E4). Further, since the contact impedance is mostly attributed to the acellular outer layer of the skin, in our experiment, we attempted to study the effect of this layer by comparing the results when the skin is intact and when electrodes are introduced underneath the skin through small cuts. This boundary effect was assessed by comparison of measurements obtained during E2 skin surface contact, and sub-cutaneous contact (E5). Twelve gauge intradermal needles were also tested as an electrode (E6). The full impedance spectrum, from 500 Hz to 300 kHz, was recorded, analysed and compared. As expected, the contact impedance in the more invasive cases, i.e the electrodes under the skin, is significantly lower than in the non-invasive cases. At the frequency of 50 kHz which is commonly used in lung EIT acquisition, electrodes E3, E4 and E6 demonstrated contact impedance of less than 200 ?, compared to more than 400 ? measured for electrodes E1, E2 and E5. In conclusion, the novel multipoint electrodes proved to be best suited for EIT purposes, because they are non-invasive and have lower contact impedance than Ag/AgCl and crocodile clips, in both invasive and non-invasive cases. This further prompted us to design a flexible electrode belt using the novel multi-point electrodes for lung EIT on animal models.

  7. Non-invasive measurement of the input-output properties of peripheral nerve stimulating electrodes.

    PubMed

    Grill, W M; Mortimer, J T

    1996-03-01

    A non-invasive method was developed to determine the input-output (I/O) properties of peripheral nerve stimulating electrodes. An apparatus was fabricated to measure the 3-dimensional (3-D) isometric torque generated at the cat ankle joint by electrical activation of the sciatic nerve. The performance of the apparatus was quantified, and the utility of the method was demonstrated by measuring the recruitment properties of multiple contact nerve cuff electrodes. Torque-twitch waveforms, recruitment curves of peak torque as a function of stimulus current amplitude, and 2-D joint torque vectors were used to analyze the recruitment properties of the cuff. The peak of the twitch torque was an accurate measure of excitation even for muscles having fibers with varying speeds of contraction. The evoked twitch waveforms and torque vectors generated by selective stimulation of individual nerve branches with a hook electrode were compared to those produced by stimulation of the nerve trunk with the cuff electrode. These data allowed determination of the regions of the nerve trunk that were activated by different electrode geometries and stimulus parameters. The positional stability of electrode recruitment properties could be quantified by measuring I/O characteristics at different limb positions. The methods described are useful for characterization of neural stimulating electrodes and for studies of motor system physiology. PMID:8815307

  8. Oxidation of S(IV) in Seawater by Pulsed High Voltage Discharge Plasma with TiO2/Ti Electrode as Catalyst

    NASA Astrophysics Data System (ADS)

    Gong, Jianying; Zhang, Xingwang; Wang, Xiaoping; Lei, Lecheng

    2013-12-01

    Oxidation of S(IV) to S(VI) in the effluent of a flue gas desulfurization(FGD) system is very critical for industrial applications of seawater FGD. This paper reports a pulsed corona discharge oxidation process combined with a TiO2 photocatalyst to convert S(IV) to S(VI) in artificial seawater. Experimental results show that the oxidation of S(IV) in artificial seawater is enhanced in the pulsed discharge plasma process through the application of TiO2 coating electrodes. The oxidation rate of S(IV) using Ti metal as a ground electrode is about 2.0×10-4 mol · L-1 · min-1, the oxidation rate using TiO2/Ti electrode prepared by annealing at 500°C in air is 4.5×10-4 mol · L-1 · min-1, an increase with a factor 2.25. The annealing temperature for preparing TiO2/Ti electrode has a strong effect on the oxidation of S(IV) in artificial seawater. The results of in-situ emission spectroscopic analysis show that chemically active species (i.e. hydroxyl radicals and oxygen radicals) are produced in the pulsed discharge plasma process. Compared with the traditional air oxidation process and the sole plasma-induced oxidation process, the combined application of TiO2 photocatalysts and a pulsed high-voltage electrical discharge process is useful in enhancing the energy and conversion efficiency of S(IV) for the seawater FGD system.

  9. The coefficient of the voltage induced frequency shift measurement on a quartz tuning fork.

    PubMed

    Hou, Yubin; Lu, Qingyou

    2014-01-01

    We have measured the coefficient of the voltage induced frequency shift (VIFS) of a 32.768 KHz quartz tuning fork. Three vibration modes were studied: one prong oscillating, two prongs oscillating in the same direction, and two prongs oscillating in opposite directions. They all showed a parabolic dependence of the eigen-frequency shift on the bias voltage applied across the fork, due to the voltage-induced internal stress, which varies as the fork oscillates. The average coefficient of the VIFS effect is as low as several hundred nano-Hz per millivolt, implying that fast-response voltage-controlled oscillators and phase-locked loops with nano-Hz resolution can be built. PMID:25414971

  10. A new method for measuring the Faradic resistance of a single electrode-electrolyte interface.

    PubMed

    Mayer, S; Geddes, L A; Bourland, J D; Ogborn, L

    1992-03-01

    A new method is described for measuring the Faradic resistance of a single electrode-electrolyte interface. The method employs a test (monopolar) electrode, a potential-sensing electrode and a large reference (indifferent) electrode, along with a constant-current source capable of providing a step function of current. The method was used to measure the Faradic resistance of a 0.1 cm2 platinum electrode in contact with saline (p = 150 ohm-cm) at room temperature. It was found that for both a positive and negative current pulse, the Faradic resistance decreased almost hyperbolically with increasing current density. When the reciprocal of the Faradic resistance (Gf) was plotted versus current density and the data were fit to a polynomial curve, the results showed that for the positive pulse Gf = 0.009 + 0.05J - 0.0001J2; (SEE = 0.117); for the negative pulse, Gf = 0.007 + 0.067J - 0.0001J2; (SEE = 0.028); where Gf is in millisiemens and J is in mA/cm2 for this 0.1 cm2 electrode. These relationships permit estimating the Faradic resistance (Rf) for zero current density. For the positive pulse, Rf = 111 kilohms and for the negative pulse Rf = 143 kilohms. The method is applicable to the measurement of the Faradic resistance of a wide variety of metal electrodes. PMID:1575647

  11. Measuring bi-directional current through a field-effect transistor by virtue of drain-to-source voltage measurement

    DOEpatents

    Turner, Steven Richard

    2006-12-26

    A method and apparatus for measuring current, and particularly bi-directional current, in a field-effect transistor (FET) using drain-to-source voltage measurements. The drain-to-source voltage of the FET is measured and amplified. This signal is then compensated for variations in the temperature of the FET, which affects the impedance of the FET when it is switched on. The output is a signal representative of the direction of the flow of current through the field-effect transistor and the level of the current through the field-effect transistor. Preferably, the measurement only occurs when the FET is switched on.

  12. Measurement system for determination of current-voltage characteristics of PV modules

    NASA Astrophysics Data System (ADS)

    Idzkowski, Adam; Walendziuk, Wojciech; Borawski, Mateusz; Sawicki, Aleksander

    2015-09-01

    The realization of a laboratory stand for testing photovoltaic panels is presented here. The project of the laboratory stand was designed in SolidWorks software. The aim of the project was to control the electrical parameters of a PV panel. For this purpose a meter that measures electrical parameters i.e. voltage, current and power, was realized. The meter was created with the use of LabJack DAQ device and LabVIEW software. The presented results of measurements were obtained in different conditions (variable distance from the source of light, variable tilt angle of the panel). Current voltage characteristics of photovoltaic panel were created and all parameters could be detected in different conditions. The standard uncertainties of sample voltage, current, power measurements were calculated. The paper also gives basic information about power characteristics and efficiency of a solar cell.

  13. Improvement of Electrical Stimulation Protocol for Simultaneous Measurement of Extracellular Potential with On-Chip Multi-Electrode Array System

    NASA Astrophysics Data System (ADS)

    Kaneko, Tomoyuki; Nomura, Fumimasa; Hattori, Akihiro; Yasuda, Kenji

    2012-06-01

    Cardiotoxicity testing with a multi-electrode array (MEA) system requires the stable beating of cardiomyocytes for the measurement of the field potential duration (FPD), because different spontaneous beating rates cause different responses of FPD prolongation induced by drugs, and the beating rate change effected by drugs complicates the FPD prolongation assessment. We have developed an on-chip MEA system with electrical stimulation for the measurement of the FPD during the stable beating of human embryonic stem (ES) cell-derived cardiomyocyte clusters. Using a conventional bipolar stimulation protocol, we observed such large artifacts in electrical stimulation that we could not estimate the FPD quantitatively. Therefore, we improved the stimulation protocol by using sequential rectangular pulses in which the positive and negative stimulation voltages and number of pulses could be changed flexibly. The balanced voltages and number of pulses for sequential rectangular pulses enabled the recording of small negative artifacts only, which hardly affected the FPD measurement of human-ES-cell-derived cardiomyocyte clusters. These conditions of electrical stimulation are expected to find applications for the control of constant beating for cardiotoxicity testing.

  14. Low-voltage pulsed plasma discharges inside water using a bubble self-generating parallel plate electrode with a porous ceramic

    NASA Astrophysics Data System (ADS)

    Muradia, Sonia; Nagatsu, Masaaki

    2013-04-01

    Characteristics of pulsed bubbles discharges in water were investigated using parallel punched plate electrodes with a porous thin ceramic plate inserted between two metal plates. The micro-bubbles were generated just beneath the porous ceramic plate by flowing gas through it. The transition from spiky dielectric barrier discharges to pulsed glow discharges enables efficient bubble discharges at a relatively low voltage of 1.8 ˜ 4.0 kV of the 5 kHz square-waves with a pulse-width of about 750 ns. With 80% Ar and 20% O2 mixture gas at 4.0 kV, the 50 mg/l Indigo Carmine aqueous solution was efficiently decolorized within about 3 min.

  15. Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement

    DOEpatents

    Kikta, Thomas J. (Pittsburgh, PA); Mitchell, Ronald D. (Pittsburgh, PA)

    1992-01-01

    A method and apparatus for determining the extent of contact between an electrically conducting tube and an electrically conductive tubesheet surrounding the tube, based upon the electrical resistance of the tube and tubesheet. A constant current source is applied to the interior of the electrically conducting tube by probes and a voltmeter is connected between other probes to measure the voltage at the point of current injection, which is inversely proportional to the amount of contact between the tube and tubesheet. Namely, the higher the voltage measured by the voltmeter, the less contact between the tube and tubesheet.

  16. A test technique for measuring lightning-induced voltages on aircraft electrical circuits

    NASA Technical Reports Server (NTRS)

    Walko, L. C.

    1974-01-01

    The development of a test technique used for the measurement of lightning-induced voltages in the electrical circuits of a complete aircraft is described. The resultant technique utilizes a portable device known as a transient analyzer capable of generating unidirectional current impulses similar to lightning current surges, but at a lower current level. A linear relationship between the magnitude of lightning current and the magnitude of induced voltage permitted the scaling up of measured induced values to full threat levels. The test technique was found to be practical when used on a complete aircraft.

  17. Method and apparatus for remote tube crevice detection by current and voltage probe resistance measurement

    DOEpatents

    Kikta, T.J.; Mitchell, R.D.

    1992-11-24

    A method and apparatus for determining the extent of contact between an electrically conducting tube and an electrically conductive tubesheet surrounding the tube, based upon the electrical resistance of the tube and tubesheet. A constant current source is applied to the interior of the electrically conducting tube by probes and a voltmeter is connected between other probes to measure the voltage at the point of current injection, which is inversely proportional to the amount of contact between the tube and tubesheet. Namely, the higher the voltage measured by the voltmeter, the less contact between the tube and tubesheet. 4 figs.

  18. Method of glass melter electrode length measurement using time domain reflectometry (TDR)

    SciTech Connect

    Tarpley, James M.; Zamecnik, John R.

    2000-02-28

    The present invention overcomes the drawbacks inherent in the prior art and solves the problems inherent in conventional Joule-heated vitrification melters, where the melter preferably comprises a vessel having a refractory liner and an opening for receiving material which is converted into molten vitreous material in the vessel. The vessel has an outlet port for removing molten vitreous material from the vessel. A plurality of electrodes is disposed in the vessel and electrical energy is passed between electrode pairs through feed material and molten vitreous material in the vessel. Typically, the electrodes erode and wear in time, and this invention seeks to monitor and evaluate the length and condition of the electrodes. The present invention uses time domain reflectometry (TDR) methods to accurately measure the length of an electrode that is subject to wear and electrolytic decomposition due to the extreme conditions in which the electrode is required to operate. Specifically, TDR would be used to measure the length and effects of erosion of molybdenum electrodes used in Joule-heated vitrification melter. Of course, the inventive concept should not be limited to this preferred environment.

  19. Dark current measurements in humid SF6: influence of electrode roughness, relative humidity and pressure

    NASA Astrophysics Data System (ADS)

    Zavattoni, L.; Hanna, R.; Lesaint, O.; Gallot-Lavallée, O.

    2015-09-01

    The measurement of ‘dark current’ in pressurized SF6 at high electric field is performed using electrodes with a coaxial geometry. To identify the main mechanisms involved in measured currents, the influences of electrode roughness, gas pressure and relative humidity have been investigated. The experimental results reveal that charge injection from the electrode constitute the predominant process responsible for the dark current. The latter is nearly identical in positive and negative polarities, and shows an exponential increase versus the relative humidity and the electric field. The analysis of results shows that under high electric field, the emission of charged water clusters from the water films adsorbed on electrodes probably constitutes the main mechanism of charge emission.

  20. A new geometric factor for in situ resistivity measurement using four slender cylindrical electrodes.

    PubMed

    Chong, Chee-Earn; Tan, Yoke-Lin

    2008-02-01

    The four-electrode method is commonly used for in situ measurement of the electrical resistivity of biological tissues. In this paper, a new geometric factor between the resistivity and measured resistance using the four-electrode interface is derived in the prolate spheroidal coordinates and experimentally validated. Evaluation of the experimental results shows that the resistivities determined using both the derived geometric factor and a commercial conductivity meter are in close agreement even when the length of the immersed electrodes becomes long with respect to the inter-electrode spacing. The evaluation also shows the effect of the relative size of the sample volume when the limitation to semi-infinite volume begins to result in poor accuracy. PMID:18269995

  1. Potentiometric measurement of polymer-membrane electrodes based on lanthanum

    SciTech Connect

    Saefurohman, Asep Buchari, Noviandri, Indra; Syoni

    2014-03-24

    Quantitative analysis of rare earth elements which are considered as the standard method that has a high accuracy, and detection limits achieved by the order of ppm is inductively coupled plasma atomic emission spectroscopy (ICPAES). But these tools are expensive and valuable analysis of the high cost of implementation. In this study be made and characterized selective electrode for the determination of rare earth ions is potentiometric. Membrane manufacturing techniques studied is based on immersion (liquid impregnated membrane) in PTFE 0.5 pore size. As ionophores to be used tri butyl phosphate (TBP) and bis(2-etylhexyl) hydrogen phosphate. There is no report previously that TBP used as ionophore in polymeric membrane based lanthanum. Some parameters that affect the performance of membrane electrode such as membrane composition, membrane thickness, and types of membrane materials studied in this research. Manufacturing of Ion Selective Electrodes (ISE) Lanthanum (La) by means of impregnation La membrane in TBP in kerosene solution has been done and showed performance for ISE-La. FTIR spectrum results for PTFE 0.5 pore size which impregnated in TBP and PTFE blank showed difference of spectra in the top 1257 cm{sup ?1}, 1031 cm{sup ?1} and 794.7 cm{sup ?1} for P=O stretching and stretching POC from group ?OP =O. The result showed shift wave number for P =O stretching of the cluster (?OP=O) in PTFE-TBP mixture that is at the peak of 1230 cm{sup ?1} indicated that no interaction bond between hydroxyl group of molecules with molecular clusters fosforil of TBP or R{sub 3}P = O. The membrane had stable responses in pH range between 1 and 9. Good responses were obtained using 10{sup ?3} M La(III) internal solution, which produced relatively high potential. ISE-La showed relatively good performances. The electrode had a response time of 29±4.5 second and could be use for 50 days. The linear range was between 10{sup ?5} and 10{sup ?1} M.

  2. Role of measurement voltage on hysteresis loop shape in Piezoresponse Force Microscopy

    SciTech Connect

    Kim, Yunseok; Yang, J.-C.; Chu, Ying Hao; Yu, Pu; Lu, X.; Jesse, Stephen; Kalinin, Sergei V

    2012-01-01

    The dependence of on-field and off-field hysteresis loop shape in Piezoresponse Force Microscopy (PFM) on driving voltage, Vac, is explored. A nontrivial dependence of hysteresis loop parameters on measurement conditions is observed. The strategies to distinguish between paraelectric and ferroelectric states with small coercive bias and separate reversible hysteretic and non-hysteretic behaviors are suggested. Generally, measurement of loop evolution with Vac is a necessary step to establish the veracity of PFM hysteresis measurements.

  3. Factors affecting the accuracy of reference electrodes

    SciTech Connect

    Ansuini, F.J.; Dimond, J.R.

    1994-12-31

    Corrosion potential measurements are probably the most frequently made and important measurement used by corrosion engineers. They are used not only to detect the presence of galvanic cells but also to commission and maintain cathodic protection systems. When making a corrosion potential measurement, a reference electrode is exposed to the same electrolyte as the structure of interest. A voltmeter is then used to measure the potential (voltage) between the structure and the reference electrode. This paper discusses several factors which affect the reference potential established by silver/silver chloride and copper/copper sulfate reference electrodes. Data is presented on the effects of temperature, light sensitivity, contaminants and solute concentration.

  4. Advanced Ring-Shaped Microelectrode Assay Combined with Small Rectangular Electrode for Quasi-In vivo Measurement of Cell-to-Cell Conductance in Cardiomyocyte Network

    NASA Astrophysics Data System (ADS)

    Nomura, Fumimasa; Kaneko, Tomoyuki; Hamada, Tomoyo; Hattori, Akihiro; Yasuda, Kenji

    2013-06-01

    To predict the risk of fatal arrhythmia induced by cardiotoxicity in the highly complex human heart system, we have developed a novel quasi-in vivo electrophysiological measurement assay, which combines a ring-shaped human cardiomyocyte network and a set of two electrodes that form a large single ring-shaped electrode for the direct measurement of irregular cell-to-cell conductance occurrence in a cardiomyocyte network, and a small rectangular microelectrode for forced pacing of cardiomyocyte beating and for acquiring the field potential waveforms of cardiomyocytes. The advantages of this assay are as follows. The electrophysiological signals of cardiomyocytes in the ring-shaped network are superimposed directly on a single loop-shaped electrode, in which the information of asynchronous behavior of cell-to-cell conductance are included, without requiring a set of huge numbers of microelectrode arrays, a set of fast data conversion circuits, or a complex analysis in a computer. Another advantage is that the small rectangular electrode can control the position and timing of forced beating in a ring-shaped human induced pluripotent stem cell (hiPS)-derived cardiomyocyte network and can also acquire the field potentials of cardiomyocytes. First, we constructed the human iPS-derived cardiomyocyte ring-shaped network on the set of two electrodes, and acquired the field potential signals of particular cardiomyocytes in the ring-shaped cardiomyocyte network during simultaneous acquisition of the superimposed signals of whole-cardiomyocyte networks representing cell-to-cell conduction. Using the small rectangular electrode, we have also evaluated the response of the cell network to electrical stimulation. The mean and SD of the minimum stimulation voltage required for pacing (VMin) at the small rectangular electrode was 166+/-74 mV, which is the same as the magnitude of amplitude for the pacing using the ring-shaped electrode (179+/-33 mV). The results showed that the addition of a small rectangular electrode into the ring-shaped electrode was effective for the simultaneous measurement of whole-cell-network signals and single-cell/small-cluster signals on a local site in the cell network, and for the pacing by electrical stimulation of cardiomyocyte networks.

  5. "Analysis of SOFCs using reference electrodes?

    SciTech Connect

    Finklea, Harry; Chen,Xiaoke; Gerdes,Kirk; Pakalapati, Suryanarayana; Celik, Ismail

    2013-07-01

    Reference electrodes are frequently applied to isolate the performance of one electrode in a solid oxide fuel cell. However, reference electrode simulations raise doubt to veracity of data collected using reference electrodes. The simulations predict that the reported performance for the one electrode will frequently contain performance of both electrodes. Nonetheless, recent reports persistently treat data so collected as ideally isolated. This work confirms the predictions of the reference electrode simulations on two SOFC designs, and to provides a method of validating the data measured in the 3-electrode configuration. Validation is based on the assumption that a change in gas composition to one electrode does not affect the impedance of the other electrode at open circuit voltage. This assumption is supported by a full physics simulation of the SOFC. Three configurations of reference electrode and cell design are experimentally examined using various gas flows and two temperatures. Impedance data are subjected to deconvolution analysis and equivalent circuit fitting and approximate polarization resistances of the cathode and anode are determined. The results demonstrate that the utility of reference electrodes is limited and often wholly inappropriate. Reported impedances and single electrode polarization values must be scrutinized on this basis.

  6. Two-point concrete resistivity measurements: interfacial phenomena at the electrode-concrete contact zone

    NASA Astrophysics Data System (ADS)

    McCarter, W. J.; Taha, H. M.; Suryanto, B.; Starrs, G.

    2015-08-01

    Ac impedance spectroscopy measurements are used to critically examine the end-to-end (two-point) testing technique employed in evaluating the bulk electrical resistivity of concrete. In particular, this paper focusses on the interfacial contact region between the electrode and specimen and the influence of contacting medium and measurement frequency on the impedance response. Two-point and four-point electrode configurations were compared and modelling of the impedance response was undertaken to identify and quantify the contribution of the electrode-specimen contact region on the measured impedance. Measurements are presented in both Bode and Nyquist formats to aid interpretation. Concretes mixes conforming to BSEN206-1 and BS8500-1 were investigated which included concretes containing the supplementary cementitious materials fly ash and ground granulated blast-furnace slag. A measurement protocol is presented for the end-to-end technique in terms of test frequency and electrode-specimen contacting medium in order to minimize electrode-specimen interfacial effect and ensure correct measurement of bulk resistivity.

  7. Measurement of voltage-dependent electronic transport across amine-linked single-molecular-wire junctions

    E-print Network

    Measurement of voltage-dependent electronic transport across amine-linked single-molecular- wire. 2009 Nanotechnology 20 434009 (http://iopscience.iop.org/0957-4484/20/43/434009) Download details: IP Search Collections Journals About Contact us My IOPscience #12;IOP PUBLISHING NANOTECHNOLOGY

  8. Measurement based Voltage Stability Monitoring of Power system Garng M. Huang

    E-print Network

    using power flow analysis methods. In this paper, a method for online monitoring of a power system based to find the most vulnerable area in a system, to find the impacts of other loads, areas and powerMeasurement based Voltage Stability Monitoring of Power system Garng M. Huang huang

  9. Threshold voltage as a measure of molecular level shift in organic thin-film transistors

    E-print Network

    Tal, Oren

    of OTFTs requires a deep understanding of charge carrier transport mechanisms through the organic layer as the gate-source voltage VGS for which there is no space charge region in the organic film.6,7 Vt also; a Inset IDS-VGS curve measured on the OFET. b Schematic energy levels structure across the OFET near

  10. Enhancement of AMTEC electrodes and current collectors

    NASA Astrophysics Data System (ADS)

    Svedberg, Robert C.; Pantolin, Jan E.; Sievers, Robert K.; Hunt, Thomas K.

    1995-01-01

    An improved electrode deposition technique has been developed for a Alkali Metal Thermal to Electric Converter (AMTEC). The innovative Sodium Modulated Electrode (SME) deposition technique has been developed which selectively deposits the electrode on inactive Na sites and adjacent to active Na sites on the electrolyte surface. This program has demonstrated SME processing feasibility and achieved electrode performance enhancement. Power density was improved by 51 to 56% at 973 K and 19 to 26% at 1073 K at the start of electrode testing. Na+ has been conducted through the beta''-alumina solid electrolyte (BASE) during the deposition process. Electrode deposition has been a random process, covering both active and inactive sites on the BASE. This random process did not optimize electrode placement or provide pore openings at the Na active sites to permit Na+ easy access to electrons and a low resistance path for Na atoms to move to the condenser. Both Mo and TiN electrodes were evaluated. It has been demonstrated that sputter deposition, with significant Na+ current being transported through the BASE at a controlled rate, is possible for both Mo and TiN. Two sputtering systems, for Mo and TiN, were modified with heater and voltage feedthroughs. The BASE temperture and the Na+ flow through the BASE was controlled. Patch electrodes were deposited using various Na+ currents and substrate temperatures. Four Mo and two TiN electrode sets were deposited and evaluated. Electrical testing was done in a Demountable Test Cell (DTC) where the current-voltage (IV) relationship was measured as a function of temperature. Electrodes were visually examined by scanning electron microscopy (SEM). The initial electrode performance has been improved by these processes. The IV data was used to evaluate electrode parameters by fitting an electrode/cell model output to the IV curves. Electrode enhancement can improve cell maximum power density performance by 87% and efficiency at optimum cell current by 22% based on clculations modelling state of the art cells.

  11. An investigation of breakdown voltage in AMTECs

    NASA Astrophysics Data System (ADS)

    Momozaki, Yoichi; El-Genk, Mohamed S.

    2002-01-01

    Experiments are conducted to investigate the DC electrical breakdown voltage in cesium vapor between two planner molybdenum electrodes, 1.6 cm in diameter, separated by a 0.5 mm gap, and relate the results to the potential electrical breakdown on the cathode side of Alkali Metal Thermal-to-Electric Converters (AMTECs). In the first set of experiments, in which the electrodes are kept at 560 and 650 K, while varying the cesium pressure from 0.71 to 29 Pa, when the cooler electrode is positively biased, breakdown occurs at ~500 V, but at 700 V when the cooler electrode is negatively biased. In the second set of experiments, in which the electrodes are held at 625 and 1100 K and the cesium pressure varied from 1.7 to 235 Pa, when the cooler electrode is positively biased, breakdown voltage is <4 V, but in excess of 400 V when the cooler electrode is negatively biased. Since the first ionization potential and the ionization rate constant of cesium are lower and higher, respectively, than for the sodium (5.14 V) and potassium (4.34 V) vapors in AMTECs, the DC electrical breakdown voltage in an AMTEC is expected to be higher than measured in this work for cesium vapor. .

  12. Voltage measurements at the vacuum post-hole convolute of the ? pulsed-power accelerator

    SciTech Connect

    Waisman, E.? M.; McBride, R. D.; Cuneo, M.? E.; Wenger, D.? F.; Fowler, W.? E.; Johnson, W.? A.; Basilio, L.? I.; Coats, R.? S.; Jennings, C.? A.; Sinars, D.? B.; Vesey, R.? A.; Jones, B.; Ampleford, D.? J.; Lemke, R.? W.; Martin, M.? R.; Schrafel, P.? C.; Lewis, S. ?A.; Moore, J.? K.; Savage, M.? E.; Stygar, W. A.

    2014-11-08

    Presented are voltage measurements taken near the load region on the Z pulsed-power accelerator using an inductive voltage monitor (IVM). Specifically, the IVM was connected to, and thus monitored the voltage at, the bottom level of the accelerator’s vacuum double post-hole convolute. Additional voltage and current measurements were taken at the accelerator’s vacuum-insulator stack (at a radius of 1.6 m) by using standard D-dot and B-dot probes, respectively. During postprocessing, the measurements taken at the stack were translated to the location of the IVM measurements by using a lossless propagation model of the Z accelerator’s magnetically insulated transmission lines (MITLs) and a lumped inductor model of the vacuum post-hole convolute. Across a wide variety of experiments conducted on the Z accelerator, the voltage histories obtained from the IVM and the lossless propagation technique agree well in overall shape and magnitude. However, large-amplitude, high-frequency oscillations are more pronounced in the IVM records. It is unclear whether these larger oscillations represent true voltage oscillations at the convolute or if they are due to noise pickup and/or transit-time effects and other resonant modes in the IVM. Results using a transit-time-correction technique and Fourier analysis support the latter. Regardless of which interpretation is correct, both true voltage oscillations and the excitement of resonant modes could be the result of transient electrical breakdowns in the post-hole convolute, though more information is required to determine definitively if such breakdowns occurred. Despite the larger oscillations in the IVM records, the general agreement found between the lossless propagation results and the results of the IVM shows that large voltages are transmitted efficiently through the MITLs on Z. These results are complementary to previous studies [R.D. McBride et al., Phys. Rev. ST Accel. Beams 13, 120401 (2010)] that showed efficient transmission of large currents through the MITLs on Z. Taken together, the two studies demonstrate the overall efficient delivery of very large electrical powers through the MITLs on Z.

  13. Voltage measurements at the vacuum post-hole convolute of the ? pulsed-power accelerator

    DOE PAGESBeta

    Waisman, E.? M.; McBride, R. D.; Cuneo, M.? E.; Wenger, D.? F.; Fowler, W.? E.; Johnson, W.? A.; Basilio, L.? I.; Coats, R.? S.; Jennings, C.? A.; Sinars, D.? B.; et al

    2014-11-08

    Presented are voltage measurements taken near the load region on the Z pulsed-power accelerator using an inductive voltage monitor (IVM). Specifically, the IVM was connected to, and thus monitored the voltage at, the bottom level of the accelerator’s vacuum double post-hole convolute. Additional voltage and current measurements were taken at the accelerator’s vacuum-insulator stack (at a radius of 1.6 m) by using standard D-dot and B-dot probes, respectively. During postprocessing, the measurements taken at the stack were translated to the location of the IVM measurements by using a lossless propagation model of the Z accelerator’s magnetically insulated transmission lines (MITLs)more »and a lumped inductor model of the vacuum post-hole convolute. Across a wide variety of experiments conducted on the Z accelerator, the voltage histories obtained from the IVM and the lossless propagation technique agree well in overall shape and magnitude. However, large-amplitude, high-frequency oscillations are more pronounced in the IVM records. It is unclear whether these larger oscillations represent true voltage oscillations at the convolute or if they are due to noise pickup and/or transit-time effects and other resonant modes in the IVM. Results using a transit-time-correction technique and Fourier analysis support the latter. Regardless of which interpretation is correct, both true voltage oscillations and the excitement of resonant modes could be the result of transient electrical breakdowns in the post-hole convolute, though more information is required to determine definitively if such breakdowns occurred. Despite the larger oscillations in the IVM records, the general agreement found between the lossless propagation results and the results of the IVM shows that large voltages are transmitted efficiently through the MITLs on Z. These results are complementary to previous studies [R.D. McBride et al., Phys. Rev. ST Accel. Beams 13, 120401 (2010)] that showed efficient transmission of large currents through the MITLs on Z. Taken together, the two studies demonstrate the overall efficient delivery of very large electrical powers through the MITLs on Z.« less

  14. Voltage measurements at the vacuum post-hole convolute of the Z pulsed-power accelerator

    DOE PAGESBeta

    Waisman, E. M.; McBride, R. D.; Cuneo, M. E.; Wenger, D. F.; Fowler, W. E.; Johnson, W. A.; Basilio, L. I.; Coats, R. S.; Jennings, C. A.; Sinars, D. B.; et al

    2014-12-08

    Presented are voltage measurements taken near the load region on the Z pulsed-power accelerator using an inductive voltage monitor (IVM). Specifically, the IVM was connected to, and thus monitored the voltage at, the bottom level of the accelerator’s vacuum double post-hole convolute. Additional voltage and current measurements were taken at the accelerator’s vacuum-insulator stack (at a radius of 1.6 m) by using standard D-dot and B-dot probes, respectively. During postprocessing, the measurements taken at the stack were translated to the location of the IVM measurements by using a lossless propagation model of the Z accelerator’s magnetically insulated transmission lines (MITLs)more »and a lumped inductor model of the vacuum post-hole convolute. Across a wide variety of experiments conducted on the Z accelerator, the voltage histories obtained from the IVM and the lossless propagation technique agree well in overall shape and magnitude. However, large-amplitude, high-frequency oscillations are more pronounced in the IVM records. It is unclear whether these larger oscillations represent true voltage oscillations at the convolute or if they are due to noise pickup and/or transit-time effects and other resonant modes in the IVM. Results using a transit-time-correction technique and Fourier analysis support the latter. Regardless of which interpretation is correct, both true voltage oscillations and the excitement of resonant modes could be the result of transient electrical breakdowns in the post-hole convolute, though more information is required to determine definitively if such breakdowns occurred. Despite the larger oscillations in the IVM records, the general agreement found between the lossless propagation results and the results of the IVM shows that large voltages are transmitted efficiently through the MITLs on Z. These results are complementary to previous studies [R. D. McBride et al., Phys. Rev. ST Accel. Beams 13, 120401 (2010)] that showed efficient transmission of large currents through the MITLs on Z. Altogether, the two studies demonstrate the overall efficient delivery of very large electrical powers through the MITLs on Z.« less

  15. Voltage measurements at the vacuum post-hole convolute of the Z pulsed-power accelerator

    NASA Astrophysics Data System (ADS)

    Waisman, E. M.; McBride, R. D.; Cuneo, M. E.; Wenger, D. F.; Fowler, W. E.; Johnson, W. A.; Basilio, L. I.; Coats, R. S.; Jennings, C. A.; Sinars, D. B.; Vesey, R. A.; Jones, B.; Ampleford, D. J.; Lemke, R. W.; Martin, M. R.; Schrafel, P. C.; Lewis, S. A.; Moore, J. K.; Savage, M. E.; Stygar, W. A.

    2014-12-01

    Presented are voltage measurements taken near the load region on the Z pulsed-power accelerator using an inductive voltage monitor (IVM). Specifically, the IVM was connected to, and thus monitored the voltage at, the bottom level of the accelerator's vacuum double post-hole convolute. Additional voltage and current measurements were taken at the accelerator's vacuum-insulator stack (at a radius of 1.6 m) by using standard D -dot and B -dot probes, respectively. During postprocessing, the measurements taken at the stack were translated to the location of the IVM measurements by using a lossless propagation model of the Z accelerator's magnetically insulated transmission lines (MITLs) and a lumped inductor model of the vacuum post-hole convolute. Across a wide variety of experiments conducted on the Z accelerator, the voltage histories obtained from the IVM and the lossless propagation technique agree well in overall shape and magnitude. However, large-amplitude, high-frequency oscillations are more pronounced in the IVM records. It is unclear whether these larger oscillations represent true voltage oscillations at the convolute or if they are due to noise pickup and/or transit-time effects and other resonant modes in the IVM. Results using a transit-time-correction technique and Fourier analysis support the latter. Regardless of which interpretation is correct, both true voltage oscillations and the excitement of resonant modes could be the result of transient electrical breakdowns in the post-hole convolute, though more information is required to determine definitively if such breakdowns occurred. Despite the larger oscillations in the IVM records, the general agreement found between the lossless propagation results and the results of the IVM shows that large voltages are transmitted efficiently through the MITLs on Z . These results are complementary to previous studies [R. D. McBride et al., Phys. Rev. ST Accel. Beams 13, 120401 (2010)] that showed efficient transmission of large currents through the MITLs on Z . Taken together, the two studies demonstrate the overall efficient delivery of very large electrical powers through the MITLs on Z .

  16. Voltage measurements at the vacuum post-hole convolute of the Z pulsed-power accelerator

    SciTech Connect

    Waisman, E. M.; McBride, R. D.; Cuneo, M. E.; Wenger, D. F.; Fowler, W. E.; Johnson, W. A.; Basilio, L. I.; Coats, R. S.; Jennings, C. A.; Sinars, D. B.; Vesey, R. A.; Jones, B.; Ampleford, D. J.; Lemke, R. W.; Martin, M. R.; Schrafel, P. C.; Lewis, S. A.; Moore, J. K.; Savage, M. E.; Stygar, W. A.

    2014-12-08

    Presented are voltage measurements taken near the load region on the Z pulsed-power accelerator using an inductive voltage monitor (IVM). Specifically, the IVM was connected to, and thus monitored the voltage at, the bottom level of the accelerator’s vacuum double post-hole convolute. Additional voltage and current measurements were taken at the accelerator’s vacuum-insulator stack (at a radius of 1.6 m) by using standard D-dot and B-dot probes, respectively. During postprocessing, the measurements taken at the stack were translated to the location of the IVM measurements by using a lossless propagation model of the Z accelerator’s magnetically insulated transmission lines (MITLs) and a lumped inductor model of the vacuum post-hole convolute. Across a wide variety of experiments conducted on the Z accelerator, the voltage histories obtained from the IVM and the lossless propagation technique agree well in overall shape and magnitude. However, large-amplitude, high-frequency oscillations are more pronounced in the IVM records. It is unclear whether these larger oscillations represent true voltage oscillations at the convolute or if they are due to noise pickup and/or transit-time effects and other resonant modes in the IVM. Results using a transit-time-correction technique and Fourier analysis support the latter. Regardless of which interpretation is correct, both true voltage oscillations and the excitement of resonant modes could be the result of transient electrical breakdowns in the post-hole convolute, though more information is required to determine definitively if such breakdowns occurred. Despite the larger oscillations in the IVM records, the general agreement found between the lossless propagation results and the results of the IVM shows that large voltages are transmitted efficiently through the MITLs on Z. These results are complementary to previous studies [R. D. McBride et al., Phys. Rev. ST Accel. Beams 13, 120401 (2010)] that showed efficient transmission of large currents through the MITLs on Z. Altogether, the two studies demonstrate the overall efficient delivery of very large electrical powers through the MITLs on Z.

  17. Near-infrared transparent electrodes for precision TengMan electro-optic measurements: In2O3 thin-film electrodes with tunable

    E-print Network

    Ho, Seng-Tiong

    .4,6 Re- cently, Michelotti et al. reported that, compared to ITO, Al- doped ZnO exhibits improved conducting oxide TCO thin films are usually used as top electrodes in Teng­Man measurements because they can

  18. Determining resistivity of a formation adjacent to a borehole having casing using multiple electrodes and with resistances being defined between the electrodes

    DOEpatents

    Vail, W.B. III

    1996-10-29

    Methods of operation are disclosed for different types of multiple electrode apparatus vertically disposed in a cased well to measure information related to the resistivity of adjacent geological formations from inside the cased well. The multiple electrode apparatus have a minimum of three spaced-apart voltage measurement electrodes that electrically engage the interior of the cased well. Measurement information is obtained related to current which is caused to flow from the cased well into the adjacent geological formation. First compensation information is obtained related to a first casing resistance between a first pair of the spaced-apart voltage measurement electrodes. Second compensation information is obtained related to a second casing resistance between a second pair of the spaced-apart voltage measurement electrodes. The measurement information, and first and second compensation information are used to determine a magnitude related to the adjacent formation resistivity. 13 figs.

  19. Determining resistivity of a formation adjacent to a borehole having casing using multiple electrodes and with resistances being defined between the electrodes

    DOEpatents

    Vail, III, William B. (Bothell, WA)

    1996-01-01

    Methods of operation of different types of multiple electrode apparatus vertically disposed in a cased well to measure information related to the resistivity of adjacent geological formations from inside the cased well. The multiple electrode apparatus have a minimum of three spaced apart voltage measurement electrodes that electrically engage the interior of the cased well. Measurement information is obtained related to current which is caused to flow from the cased well into the adjacent geological formation. First compensation information is obtained related to a first casing resistance between a first pair of the spaced apart voltage measurement electrodes. Second compensation information is obtained related to a second casing resistance between a second pair of the spaced apart voltage measurement electrodes. The measurement information, and first and second compensation information are used to determine a magnitude related to the adjacent formation resistivity.

  20. The effect of electrode geometry on electrochemical properties measured in saline.

    PubMed

    Cogan, Stuart F; Ehrlich, Julia; Plante, Timothy D

    2014-01-01

    The impedance, cyclic voltammetry, and charge-injection properties of rectangular, sputtered iridium oxide (SIROF) electrodes have been measured in buffered physiological saline over a range of geometric surface areas (GSA) and perimeter-to-area ratios (P/A). Electrodes with a higher P/A are expected to have a lower impedance and higher charge injection capacity (Q(inj)), and both these effects were evident for SIROF electrodes with a GSA in the range 0.0023-0.0031 mm(2). However, the magnitude of the effect was modest. The increase in Q(inj) for rectangular electrodes with a P/A ranging from 94 to 255 mm(-1) was 21-26% depending on pulse width. There was a corresponding decrease in impedance (0.1 to 10(5) Hz) with increasing P/A and an increase in the SIROF charge storage capacity calculated from cyclic voltammetry. To assess the full usefulness of high P/A electrodes for increasing the reversible Q(inj) of an electrode, measurements should now be extended to chronic in vivo preparations. PMID:25571570

  1. Contamination of current-clamp measurement of neuron capacitance by voltage-dependent phenomena

    PubMed Central

    White, William E.

    2013-01-01

    Measuring neuron capacitance is important for morphological description, conductance characterization, and neuron modeling. One method to estimate capacitance is to inject current pulses into a neuron and fit the resulting changes in membrane potential with multiple exponentials; if the neuron is purely passive, the amplitude and time constant of the slowest exponential give neuron capacitance (Major G, Evans JD, Jack JJ. Biophys J 65: 423–449, 1993). Golowasch et al. (Golowasch J, Thomas G, Taylor AL, Patel A, Pineda A, Khalil C, Nadim F. J Neurophysiol 102: 2161–2175, 2009) have shown that this is the best method for measuring the capacitance of nonisopotential (i.e., most) neurons. However, prior work has not tested for, or examined how much error would be introduced by, slow voltage-dependent phenomena possibly present at the membrane potentials typically used in such work. We investigated this issue in lobster (Panulirus interruptus) stomatogastric neurons by performing current clamp-based capacitance measurements at multiple membrane potentials. A slow, voltage-dependent phenomenon consistent with residual voltage-dependent conductances was present at all tested membrane potentials (?95 to ?35 mV). This phenomenon was the slowest component of the neuron's voltage response, and failure to recognize and exclude it would lead to capacitance overestimates of several hundredfold. Most methods of estimating capacitance depend on the absence of voltage-dependent phenomena. Our demonstration that such phenomena make nonnegligible contributions to neuron responses even at well-hyperpolarized membrane potentials highlights the critical importance of checking for such phenomena in all work measuring neuron capacitance. We show here how to identify such phenomena and minimize their contaminating influence. PMID:23576698

  2. Verification of a novel method for tube voltage constancy measurement of orthovoltage x-ray irradiators

    PubMed Central

    Wang, Chu; Belley, Matthew D.; Chao, Nelson J.; Dewhirst, Mark W.; Yoshizumi, Terry

    2014-01-01

    Purpose: For orthovoltage x-ray irradiators, the tube voltage is one of the most fundamental system parameters as this directly relates to the dosimetry in radiation biology studies; however, to the best of our knowledge, there is no commercial portable quality assurance (QA) tool to directly test the constancy of the tube voltage greater than 160 kV. The purpose of this study is to establish the Beam Quality Index (BQI), a quantity strongly correlated to the tube voltage, as an alternative parameter for the verification of the tube voltage as part of the QA program of orthovoltage x-ray irradiators. Methods: A multipurpose QA meter and its associated data acquisition software were used to customize the measurement parameters to measure the BQI and collect its time-plot. BQI measurements were performed at 320 kV with four filtration levels on three orthovoltage x-ray irradiators of the same model, one of which had been recently energy-calibrated at the factory. Results: For each of the four filtration levels, the measured BQI values were in good agreement (<5%) between the three irradiators. BQI showed filtration-specificity, possibly due to the difference in beam quality. Conclusions: The BQI has been verified as a feasible alternative for monitoring the constancy of the tube voltage for orthovoltage irradiators. The time-plot of BQI offers information on the behavior of beam energy at different phases of the irradiation time line. In addition, this would provide power supply performance characteristics from initial ramp-up to plateau, and finally, the sharp drop-off at the end of the exposure. PMID:25086562

  3. Verification of a novel method for tube voltage constancy measurement of orthovoltage x-ray irradiators

    SciTech Connect

    Wang, Chu; Belley, Matthew D.; Chao, Nelson J.; Dewhirst, Mark W.; Yoshizumi, Terry

    2014-08-15

    Purpose: For orthovoltage x-ray irradiators, the tube voltage is one of the most fundamental system parameters as this directly relates to the dosimetry in radiation biology studies; however, to the best of our knowledge, there is no commercial portable quality assurance (QA) tool to directly test the constancy of the tube voltage greater than 160 kV. The purpose of this study is to establish the Beam Quality Index (BQI), a quantity strongly correlated to the tube voltage, as an alternative parameter for the verification of the tube voltage as part of the QA program of orthovoltage x-ray irradiators. Methods: A multipurpose QA meter and its associated data acquisition software were used to customize the measurement parameters to measure the BQI and collect its time-plot. BQI measurements were performed at 320 kV with four filtration levels on three orthovoltage x-ray irradiators of the same model, one of which had been recently energy-calibrated at the factory. Results: For each of the four filtration levels, the measured BQI values were in good agreement (<5%) between the three irradiators. BQI showed filtration-specificity, possibly due to the difference in beam quality. Conclusions: The BQI has been verified as a feasible alternative for monitoring the constancy of the tube voltage for orthovoltage irradiators. The time-plot of BQI offers information on the behavior of beam energy at different phases of the irradiation time line. In addition, this would provide power supply performance characteristics from initial ramp-up to plateau, and finally, the sharp drop-off at the end of the exposure.

  4. AN EVALUATION OF ELECTRODE INSERTION TECHNIQUES FOR MEASUREMENT OF REDOX POTENTIAL IN ESTUARINE SEDIMENTS

    EPA Science Inventory

    Eh measurements by electrodes are commonly used to characterize redox status of sediments in freshwater, marine and estuarine studies, due to the relative ease and rapidity of data collection. In our studies of fine-grained estuarine seabeds, we observed that Eh values measured i...

  5. Performance of lightweight nickel electrodes

    NASA Technical Reports Server (NTRS)

    Britton, Doris L.

    1988-01-01

    The NASA Lewis Research Center is currently developing nickel electrodes for nickel-hydrogen (Ni-H2) batteries. These electrodes are lighter in weight and have higher energy densities than the heavier state-of-the-art (SOA) sintered nickel electrodes. In the present approach, lightweight materials or plaques are used as conductive supports for the nickel hydroxide active material. These plaques (fiber and felt, nickel plated plastic and graphite) are commercial products that are fabricated into nickel electrodes by electrochemically impregnating them with active material. Evaluation is performed in half cells structured in the bipolar configuration. Initial performance tests include capacity measurements at five discharge levels, C/2, 1.0C 1.37C, 2.0C and 2.74C. The electrodes that pass the initial tests are life cycle tested in a low Earth orbit regime at 80 percent depth of discharge. Different formulations of nickel fiber materials obtained from several manufacturers are currently being tested as possible candidates for nickel electrodes. One particular lightweight fiber mat electrode has accumulated over 3000 cycles to date, with stable capacity and voltage. Life and performance data of this electrode were investigated and presented. Good dimensional stability and active material adherence have been demonstrated in electrodes made from this lightweight plaque.

  6. Wavelength stabilisation of a DFB laser diode using measurement of junction voltage

    NASA Astrophysics Data System (ADS)

    Asmari, A.; Hodgkinson, J.; Chehura, E.; Staines, S. E.; Tatam, R. P.

    2014-05-01

    Laser diode wavelength stability is vital for applications such as spectroscopy and data communication, and the emitted wavelength is a function of temperature. In a conventional system, the laser diode temperature is controlled using a Peltier element with a temperature-sensing thermistor, the latter placed at a short distance from the laser diode chip. Despite the use of good thermal design and a case, a change in ambient temperature may cause a change to internal thermal gradients, resulting in a systematic error in the laser diode wavelength. In this paper we describe a novel system to measure the temperature of the laser diode junction via measurement of the junction voltage. The method has been applied to a 1651 nm DFB laser diode for use in tunable diode laser spectroscopy (TDLS) of methane. The wavelength stability of both thermistor- and voltage- control systems are compared over a period of 30 minutes and with different ambient temperatures. Over 30 min at constant ambient temperature, thermistor control provided a precision of +/- 0.4 pm (40 MHz) and junction voltage control gave a similar +/- 0.6 pm (70 MHz). For an ambient temperature change of 20°C, conventional thermistor control suffered a wavelength change of 76 pm (8.4 GHz), whereas junction voltage control reduced this to 0.6 pm (70 MHz), at or below the level of long-term wavelength precision.

  7. in the lipid bilayer Distance measurements reveal a common topology of prokaryotic voltage-gated ion channels

    E-print Network

    Bezanilla, Francisco

    in the lipid bilayer Distance measurements reveal a common topology of prokaryotic voltage.pnas.org/misc/reprints.shtml To order reprints, see: Notes: #12;Distance measurements reveal a common topology of prokaryotic voltage conformations in a mem- brane environment. The validity of the crystal structure for the prokaryotic K channel

  8. Measurement of Component Cell Current-Voltage Characteristics in a Tandem-JunctionTwo-Terminal Solar Cell

    E-print Network

    Deng, Xunming

    Measurement of Component Cell Current-Voltage Characteristics in a Tandem- JunctionTwo-Terminal Solar Cell Chandan Das, Xianbi Xiang and Xunming Deng Department of Physics and Astronomy, University of Toledo, Toledo, Ohio 43606 Abstract A new method for measuring component cell current-voltage (I

  9. High altitude current-voltage measurement of GaAs/Ge solar cells

    NASA Technical Reports Server (NTRS)

    Hart, Russell E., Jr.; Brinker, David J.; Emery, Keith A.

    1988-01-01

    Measurements of high-voltage (Voc of 1.2 V) gallium arsenide on germanium tandem junction solar cells at air mass 0.22 showed that the insolation in the red portion of the solar spectrum is insufficient to obtain high fill factor. On the basis of measurements in the LeRC X-25L solar simulator, these cells were believed to be as efficient as 21.68 percent AM0. Solar simulator spectrum errors in the red end allowed the fill factor to be as high as 78.7 percent. When a similar cell's current-voltage characteristic was measured at high altitude in the NASA Lear Jet Facility, a loss of 15 percentage points in fill factor was observed. This decrease was caused by insufficient current in the germanium bottom cell of the tandem stack.

  10. Forward voltage short-pulse technique for measuring high power laser array junction temperature

    NASA Technical Reports Server (NTRS)

    Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)

    2012-01-01

    The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

  11. Impedance studies of nickel/cadmium and nickel/hydrogen cells using the cell case as a reference electrode

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1990-01-01

    Impedance measurements have been made on several Ni/Cd and Ni/H2 flight-weight cells using the case as a reference electrode. For these measurements, the voltage of the case with respect to the anode or cathode is unimportant provided that it remains stable during the measurement of the impedance. In the cells measured so far, the voltage of the cell cases with respect to the individual electrodes differ from cell to cell, even at the same overall cell voltage, but they remain stable with time. The measurements can thus be used to separate the cell impedance into the contributions of each electrode, allowing improved diagnosis of cell problems.

  12. A Cylindrical Capacitance Sensor with Three Electrodes for Liquid-Level Measurement in Two Different Conditions

    NASA Astrophysics Data System (ADS)

    Lu, Guirong; Shida, Katsunori

    In this paper, a practical sensing approach for monitoring the liquid-level in a container is presented. In this research we have developed a new structure sensor with three electrodes. When the container becomes inclined from vertical condition during measuring process, the liquid-level in the liquid container is determined correctly by detecting the change in capacitance between every two electrodes. In this process, a multidimensional regression equation based on experiment data is adopted. The result of this research proves that the designed sensor can be used to measure the liquid-level in the container unrelated to inclination.

  13. Effect of Y Content in (TaC)1-xYx Gate Electrodes on Flatband Voltage Control for Hf-Based High-k Gate Stacks

    NASA Astrophysics Data System (ADS)

    Homhuan, Pattira; Nabatame, Toshihide; Chikyow, Toyohiro; Tungasmita, Sukkaneste

    2011-10-01

    The effects of varying the yttrium (Y) level in a (TaC)1-xYx gate electrode on the structural and electrical properties of a hafnium (Hf)-based high-k metal-oxide-semiconductor (MOS) capacitor, including flatband voltage (Vfb), were evaluated. The composition of (TaC)1-xYx was controlled by the power of pure TaC and Y targets in magnetron sputtering. The structure of the formed (TaC)1-xYx film was that of either a face-center cubic (fcc) at all compositions of x?0.4 or amorphous at x?0.5 after annealing at temperatures below 600 °C. X-ray photoelectron spectroscopy (XPS) analysis revealed that the TaC and (TaC)1-xYx films all contained about 10% oxygen. The resistivity of the (TaC)1-xYx films was invariant for all compositions of x?0.5, but it increased with increasing annealing temperature up to 600 °C for compositions of x?0.68. In the as-deposited case, the effective work function, which was estimated from the relationship between Vfb and the equivalent oxide thickness of the HfO2 film, clearly changed from 4.8 to 4.3 eV as x increased. The Vfb of HfO2 and HfSiOx dielectrics could be controlled within 0.5 V after annealing at 500 °C by changing the composition of the (TaC)1-xYx film (in terms of x). Based on the experimental data, it is clear that (TaC)1-xYx composites are candidate materials for n-metal gate electrodes in the gate-last process.

  14. Electrochemical and morphological study of the effect of temperature on the restructuring and loss of capacity of alkaline battery electrodes

    SciTech Connect

    Lenhart, S.J.; Chao, C.Y.; MacDonald, D.D.

    1981-01-01

    Alkaline battery electrode restructuring is being studied using ac impedance and ellipsometric techniques. Porous electrodes have been modeled as transmission lines, and the electrochemical properties (e.g., impedance and voltage drop in the pores) of the electrodes are being derived in terms of measurable physical properties. 5 refs.

  15. Correlation between measured voltage and observed wavelength in commercial AlGaInP laser diode

    SciTech Connect

    Iskrenovi?, Predrag S.; Krsti?, Ivan B.; Obradovi?, Bratislav M. Kuraica, Milorad M.

    2014-05-14

    Temperature of a commercial AlGaInP/GaInP quantum well laser diode (LD) is measured using two methods: peak wavelength shift and the diode voltage drop caused by working current. Time evolutions of temperature obtained by the two methods during the LD self-heating are measured and compared. No significant difference between the thus obtained temperature evolutions is obtained. Correlation between the LD voltage drop and the laser radiation frequency is established using a simple four-level semiconductor laser scheme and the LD gap energy is estimated. The LD gap energy decreases from 1.66?eV to 1.56?eV for temperature increase of 21?K, at close to room temperature. It is found that LD's frequency decrease is caused by the gap energy decrease.

  16. SPEAR-1: An experiment to measure current collection in the ionosphere by high voltage biased conductors

    NASA Technical Reports Server (NTRS)

    Raitt, W. John; Myers, Neil B.; Roberts, Jon A.; Thompson, D. C.

    1990-01-01

    An experiment is described in which a high electrical potential difference, up to 45 kV, was applied between deployed conducting spheres and a sounding rocket in the ionosphere. Measurements were made of the applied voltage and the resulting currents for each of 24 applications of different high potentials. In addition, diagnostic measurements of optical emissions in the vicinity of the spheres, energetic particle flow to the sounding rocket, dc electric field and wave data were made. The ambient plasma and neutral environments were measured by a Langmuir probe and a cold cathode neutral ionization gauge, respectively. The payload is described and examples of the measured current and voltage characteristics are presented. The characteristics of the measured currents are discussed in terms of the diagnostic measurements and the in-situ measurements of the vehicle environment. In general, it was found that the currents observed were at a level typical of magnetically limited currents from the ionospheric plasma for potentials less than 12 kV, and slightly higher for larger potentials. However, due to the failure to expose the plasma contactor, the vehicle sheath modified the sphere sheaths and made comparisons with the analytic models of Langmuir-Blodgett and Parker-Murphy less meaningful. Examples of localized enhancements of ambient gas density resulting from the operation of the attitude control system thrusters (cold nitrogen) were obtained. Current measurements and optical data indicated localized discharges due to enhanced gas density that reduced the vehicle-ionosphere impedance.

  17. Electrolyte measurement device and measurement procedure

    DOEpatents

    Cooper, Kevin R. (Southern Pines, NC); Scribner, Louie L. (Southern Pines, NC)

    2010-01-26

    A method and apparatus for measuring the through-thickness resistance or conductance of a thin electrolyte is provided. The method and apparatus includes positioning a first source electrode on a first side of an electrolyte to be tested, positioning a second source electrode on a second side of the electrolyte, positioning a first sense electrode on the second side of the electrolyte, and positioning a second sense electrode on the first side of the electrolyte. current is then passed between the first and second source electrodes and the voltage between the first and second sense electrodes is measured.

  18. Dopant profiling and surface analysis of silicon nanowires using capacitance-voltage measurements.

    PubMed

    Garnett, Erik C; Tseng, Yu-Chih; Khanal, Devesh R; Wu, Junqiao; Bokor, Jeffrey; Yang, Peidong

    2009-05-01

    Silicon nanowires are expected to have applications in transistors, sensors, resonators, solar cells and thermoelectric systems. Understanding the surface properties and dopant distribution will be critical for the fabrication of high-performance devices based on nanowires. At present, determination of the dopant concentration depends on a combination of experimental measurements of the mobility and threshold voltage in a nanowire field-effect transistor, a calculated value for the capacitance, and two assumptions--that the dopant distribution is uniform and that the surface (interface) charge density is known. These assumptions can be tested in planar devices with the capacitance-voltage technique. This technique has also been used to determine the mobility of nanowires, but it has not been used to measure surface properties and dopant distributions, despite their influence on the electronic properties of nanowires. Here, we measure the surface (interface) state density and the radial dopant profile of individual silicon nanowire field-effect transistors with the capacitance-voltage technique. PMID:19421217

  19. Measured voltages and currents internal to closed metal cylinders due to diffusion of simulated lightning currents

    SciTech Connect

    Schnetzer, G.H.; Fisher, R.J.

    1994-08-01

    One mechanism for the penetration of lightning energy into the interior of a weapon is by current diffusion through the exterior metal case. Tests were conducted in which simulated lightning currents were driven over the exteriors of similar aluminum and ferrous steel cylinders of 0.125-in wall thickness. Under conditions in which the test currents were driven asymmetrically over the exteriors of the cylinders, voltages were measured between various test points in the interior as functions of the amplitude and duration of the applied current. The maximum recorded open-circuit voltage, which occurred in the steel cylinder, was 1.7 V. On separate shots, currents flowing on a low impedance shorting conductor between the same set of test points were also measured, yielding a maximum current of 630 A, again occurring across the interior of the steel cylinder. Under symmetrical exterior drive current conditions, a maximum end-to-end internal voltage of 4.1 V was obtained, also in the steel cylinder, with a corresponding current of 480 A measured on a coaxial conductor connected between the two end plates of the cylinder. Data were acquired over a range of input current amplitudes between about 40 and 100 kA. These data provide the experimental basis for validating models that can subsequently be applied to real weapons and other objects of interest.

  20. Effect of metallic buffer at electrode-oxide interface on current-voltage characteristics of resistive random access memories (ReRAMs): A first-principles study

    NASA Astrophysics Data System (ADS)

    Miyazaki, Takehide; Nakamura, Hisao; Nishio, Kengo; Shima, Hisashi; Akinaga, Hiroyuki; Asai, Yoshihiro

    2013-03-01

    We present the electric current (I)-voltage (V) characteristics (-1.0 eV < V < +1.0 eV) for a model of ReRAM devices with metal-oxide-metal structures, based on first principles nonequilibrium Green's function (NEGF) theory. We choose TiN and hafnia (HfO2) for the electrode and oxide materials, respectively, because this combination has been widely known in literature. We investigate the I- V characteristics for two different compositions of the TiN/HfO2 interface, (a) with and (b) without the Ta buffer layer between TiN and HfO2. We assume cubic HfO2 layers for simplicity. For case (a), a clear distinction between the ``ON'' and ``OFF'' states appears depending on the occurrence and absence of the oxygen vacancies (VOs), respectively. For case (b), however, little electric current flows even when the VOs exist in hafnia. In the latter, the O atoms abstracted from hafnia are strongly bound to N, leading to substantial separation of TiN from HfO2. In contrast, in the former, the Ta buffer not only absorbs the O atoms but also bridges TiN and HfO2 to secure the occurrence of the ``ON'' state.

  1. 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

  2. An Inexpensive Electrode and Cell for Measurement of Oxygen Uptake in Chemical and Biochemical Systems.

    ERIC Educational Resources Information Center

    Brunet, Juan E.; And Others

    1983-01-01

    The continuous measurement of oxygen consumption in an enzymatic reaction is a frequent experimental fact and extremely important in the enzymatic activity of oxygenase. An electrochemical system, based on a polarographic method, has been developed to monitor the oxygen uptake. The system developed and electrode used are described. (JN)

  3. Activity coefficients of aqueous sodium chloride from 15° to 50°C measured with a glass electrode

    USGS Publications Warehouse

    Truesdell, A.H.

    1968-01-01

    Values of the mean activity coefficient of sodium chloride at 15°, 25°, 38° and 50°C were determined for aqueous NaCl solutions of 0.01 to 1.0 molal from electromotive force measurements on the cell: (sodium-sensitive glass electrode, aqueous sodium chloride, silver chloride-silver).

  4. Activity coefficients of aqueous potassium chloride measured with a potassium-sensitive glass electrode

    USGS Publications Warehouse

    Hostetler, P.B.; Truesdell, A.H.; Christ, C.L.

    1967-01-01

    Values of ????KCI temperature and molality ranges of 10?? to 50??C and 0.01 to 1.0 molal were determined with an electromotive-force cell: potasslum-sensitive glass electrode, KCl (molality), Ag-AgCl. A more satisfactory method than is commonly employed was devised for treating the experimental measurements of potential.

  5. Human CT Measurements of Structure/Electrode Position Changes During Respiration with Electrical Impedance Tomography.

    PubMed

    Zhang, Jie; Qin, Lihong; Allen, Tadashi; Patterson, Robert P

    2013-01-01

    For pulmonary applications of Electrical Impedance Tomography (EIT) systems, the electrodes are placed around the chest in a 2D ring, and the images are reconstructed based on the assumptions that the object is rigid and the measured resistivity change in EIT images is only caused by the actual resistivity change of tissue. Structural changes are rarely considered. Previous studies have shown that structural changes which result in tissue/organ and electrode position changes tend to introduce artefacts to EIT images of the thorax. Since EIT reconstruction is an ill-posed inverse problem, any small inaccurate assumptions of object may cause large artefacts in reconstructed images. Accurate information on structure/electrode position changes is a need to understand factors contributing to the measured resistivity changes and to improve EIT reconstruction algorithm. Our previous study using MRI technique showed that chest expansion leads to electrode and tissue/organ movements but not significant as proposed. The accuracy of the measurements by MRI may be limited by its relatively low temporal and spatial resolution. In this study, structure/electrode position changes during respiration cycle in patients who underwent chest CT scans are further investigated. For each patient, sixteen fiduciary markers are equally spaced around the surface, the same as the electrode placement for EIT measurements. A CT scanner with respiration-gated ability is used to acquire images of the thorax. CT thoracic images are retrospectively reconstructed corresponding temporally to specific time periods within respiration cycle (from 0% to 90%, every 10%). The average chest expansions are 2 mm in anterior-posterior and -1.6 mm in lateral directions. Inside tissue/organ move down 9.0±2.5 mm with inspiration of tidal volume (0.54±0.14 liters), ranging from 6 mm to 12 mm. During normal quiet respiration, electrode position changes are smaller than expected. No general patterns of electrode position changes are observed. The results in this study provide guidelines for accommodating the motion that may introduce artefacts to EIT images. PMID:24339836

  6. Single-Molecule Electronic Measurements with Metal Electrodes

    ERIC Educational Resources Information Center

    Lindsay, Stuart

    2005-01-01

    A review of concepts like tunneling through a metal-molecule-metal-junction, contrast with electrochemical and optical-charge injection, strong-coupling limit, calculations of tunnel transport, electron transfer through Redox-active molecules is presented. This is followed by a discussion of experimental approaches for single-molecule measurements.

  7. In situ current voltage measurements for optimization of a novel fullerene acceptor in bulk heterojunction photovoltaics

    SciTech Connect

    Shuttle, Christopher G.; Treat, Neil D.; Fan, Jian; Varotto, Alessandro; Hawker, Craig J.; Wudl, Fred; Chabinyc, Michael L.

    2011-10-31

    The evaluation of the power conversion efficiency (PCE) of new materials for organic bulk heterojunction (BHJ) photovoltaics is difficult due to the large number of processing parameters possible. An efficient procedure to determine the optimum conditions for thermal treatment of polymer-based bulk heterojunction photovoltaic devices using in situ current-voltage measurements is presented. The performance of a new fullerene derivative, 1,9-dihydro-64,65-dihexyloxy-1,9-(methano[1,2] benzomethano)fullerene[60], in BHJ photovolatics with poly(3-hexylthiophene) (P3HT) was evaluated using this methodology. The device characteristics of BHJs obtained from the in situ method were found to be in good agreement with those from BHJs annealed using a conventional process. This fullerene has similar performance to 1-(3-methoxycarbonyl)propyl-1-phenyl-[6,6]-methano fullerene in BHJs with P3HT after thermal annealing. For devices with thickness of 70 nm, the short circuit current was 6.24 mA/cm² with a fill factor of 0.53 and open circuit voltage of 0.65 V. The changes in the current-voltage measurements during thermal annealing suggest that the ordering process in P3HT dominates the improvement in power conversion efficiency.

  8. Space charge inhibition effect of nano-Fe3O4 on improvement of impulse breakdown voltage of transformer oil based on improved Kerr optic measurements

    NASA Astrophysics Data System (ADS)

    Yang, Qing; Yu, Fei; Sima, Wenxia; Zahn, Markus

    2015-09-01

    Transformer oil-based nanofluids (NFs) with 0.03 g/L Fe3O4 nanoparticle content exhibit 11.2% higher positive impulse breakdown voltage levels than pure transformer oils. To study the effects of the Fe3O4 nanoparticles on the space charge in transformer oil and to explain why the nano-modified transformer oil exhibits improved impulse breakdown voltage characteristics, the traditional Kerr electro-optic field mapping technique is improved by increasing the length of the parallel-plate electrodes and by using a photodetector array as a high light sensitivity device. The space charge distributions of pure transformer oil and of NFs containing Fe3O4 nanoparticles can be measured using the improved Kerr electro-optic field mapping technique. Test results indicate a significant reduction in space charge density in the transformer oil-based NFs with the Fe3O4 nanoparticles. The fast electrons are captured by the nanoparticles and are converted into slow-charged particles in the NFs, which then reduce the space charge density and result in a more uniform electric field distribution. Streamer propagation in the NFs is also obstructed, and the breakdown strengths of the NFs under impulse voltage conditions are also improved.

  9. Measurements of doping density in InAs by capacitance-voltage techniques with electrolyte barriers

    NASA Astrophysics Data System (ADS)

    Frolov, D.; Yakovlev, G.; Zubkov, V.

    2015-11-01

    The doping densities in n-InAs structures were studied by means of capacitance- voltage technique using electrolyte to form Schottky-like contact. It was shown that in heavily doped InAs (> 1018 cm-3) the depletion approximation can be used to obtain the true doping concentration. Concentration in low doped InAs can be estimated by simulation (using modified Thomas-Fermi approximation). Measured doping densities were compared with concentration obtained by Hall measurements. The difference between CV and Hall results in undoped samples was explained.

  10. A Remote Monitoring System for Voltage, Current, Power and Temperature Measurements

    NASA Astrophysics Data System (ADS)

    Barakat, E.; Sinno, N.; Keyrouz, C.

    This paper presents a study and design of a monitoring system for the continuous measurement of electrical energy parameters such as voltage, current, power and temperature. This system is designed to monitor the data remotely over internet. The electronic power meter is based on a microcontroller from Microchip Technology Inc. PIC family. The design takes into consideration the correct operation in the event of an outage or brown out by recording the electrical values and the temperatures in EEPROM internally available in the microcontroller. Also a digital display is used to show the acquired measurements. A computer will remotely monitor the data over internet.

  11. [Measurement and analysis of monophasic action potentials using fractally coated electrodes--II].

    PubMed

    Wetzig, T; Fröhlich, R; Bolz, A; Göhl, K; Richter, P; Gottwik, M; Schaldach, M

    1995-06-01

    The monophasic action potential (MAP) represents a summed signal formed by overlapping action potentials of myocardial cells close to the tip of the lead. Analysis of the MAP therefore provides detailed information about the electrophysiological effects of autonomous nervous and pharmacological influences on the myocardium, for example adrenergic or cholinergic stimulation of the heart. All known MAP recordings were obtained with Ag/AgCl electrodes, which, thanks to their low polarization properties, ensure reliable MAP measurement. Owing to their toxicity and inadequate long-term stability, however, Ag/AgCl electrodes cannot be implanted. With the aim of making MAP measurement available for implantable devices, fractally coated leads were therefore developed. The aim of the present study was to evaluate the in vivo measurement of fractally coated leads which are characterized by negligible polarization, low impedance over a wide frequency range, high biocompatibility and good long-term stability. In addition, as a result of their extremely high Helmholtz capacities (up to 50 mF/cm2), fractally coated leads permit stimulation and virtually undisturbed recording of MAP with the same pair of electrodes. For the evaluation of MAP measurements with fractally coated leads, a quadrupolar catheter enabling simultaneous MAP recordings with 2 Ag/AgCl electrodes and 2 fractally coated leads was devised. The stimulation pulses were always applied via the fractally coated leads. With both types of electrode, with spontaneous excitation and stimulation, the well-known MAP morphology, with amplitudes of between 10 and 25 mV in the ventricle, and between 5 and 10 mV in the atrium, was seen.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7632869

  12. A coated-wire ion-selective electrode for ionic calcium measurements

    NASA Technical Reports Server (NTRS)

    Hines, John W.; Arnaud, Sara; Madou, Marc; Joseph, Jose; Jina, Arvind

    1991-01-01

    A coated-wire ion-selective electrode for measuring ionic calcium was developed, in collaboration with Teknektron Sensor Development Corporation (TSDC). This coated wire electrode sensor makes use of advanced, ion-responsive polyvinyl chloride (PVC) membrane technology, whereby the electroactive agent is incorporated into a polymeric film. The technology greatly simplifies conventional ion-selective electrode measurement technology, and is envisioned to be used for real-time measurement of physiological and environment ionic constituents, initially calcium. A primary target biomedical application is the real-time measurement of urinary and blood calcium changes during extended exposure to microgravity, during prolonged hospital or fracture immobilization, and for osteoporosis research. Potential advanced life support applications include monitoring of calcium and other ions, heavy metals, and related parameters in closed-loop water processing and management systems. This technology provides a much simplified ionic calcium measurement capability, suitable for both automated in-vitro, in-vivo, and in-situ measurement applications, which should be of great interest to the medical, scientific, chemical, and space life sciences communities.

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  15. Local impedance measurement of an electrode/single-pentacene-grain interface by frequency-modulation scanning impedance microscopy

    NASA Astrophysics Data System (ADS)

    Kimura, Tomoharu; Kobayashi, Kei; Yamada, Hirofumi

    2015-08-01

    The device performances of organic thin film transistors are often limited by the metal-organic interface because of the disordered molecular layers at the interface and the energy barriers against the carrier injection. It is important to study the local impedance at the interface without being affected by the interface morphology. We combined frequency modulation atomic force microscopy with scanning impedance microscopy (SIM) to sensitively measure the ac responses of the interface to an ac voltage applied across the interface and the dc potential drop at the interface. By using the frequency-modulation SIM (FM-SIM) technique, we characterized the interface impedance of a Pt electrode and a single pentacene grain as a parallel circuit of a contact resistance and a capacitance. We found that the reduction of the contact resistance was caused by the reduction of the energy level mismatch at the interface by the FM-SIM measurements, demonstrating the usefulness of the FM-SIM technique for investigation of the local interface impedance without being affected by its morphology.

  16. Voltage noise measurements across the pancreatic beta-cell membrane: calcium channel characteristics.

    PubMed Central

    Atwater, I; Dawson, C M; Eddlestone, G T; Rojas, E

    1981-01-01

    1. Membrane potential fluctuations were measured in cells from mouse Islets of Langerhans identified as beta-cells by the characteristic pattern of electrical activity induced by 11 mM-D-glucose. 2. The membrane potential was controlled by adjusting the external potassium concentration, [K+]o, keeping the sum [Na+]o plus [K+]o constant. In the absence of glucose, when [K+]o is raised, the resulting depolarization is accompanied by a significant increase in voltage noise. 3 The amplitude and time course of the voltage noise were measured under various experimental conditions. The variance of the fluctuating voltage decreased monotonically along the depolarization induced by sudden increase in [K+]o, suggesting a monotonic reduction in the number of elementary events. 4. The frequency characteristics of the excess noise could be analysed as the sum of 1/f and 1/f2 components. While the 1/f component remained unaffected by the external application of 20mM-tetraethylammonium (TEA) and either 2 mM-Mn2+ or 2 mM-Co2+, the 1/f2 component was suppressed by both Mn2+ and Co2+. 5. The corner frequency, fc, of the 1/f2 component depended on membrane potential, which was adjusted by adjusting the [K+]o jump. These results support the idea that fc in these experiments is a measure of the channel relaxation. 6. Measurements of the input resistance in the frequency range from 0 to 25 Hz were used to obtain a rough estimate of the size of the channel conductance as 5 x 10(-12) omega (-1). PMID:6273530

  17. An unattended device for high-voltage sampling and passive measurement of thoron decay products

    SciTech Connect

    Gierl, Stefanie; Meisenberg, Oliver Wielunski, Marek; Tschiersch, Jochen; Haninger, Thomas

    2014-02-15

    An integrating measurement device for the concentration of airborne thoron decay products was designed and calibrated. It is suitable for unattended use over up to several months also in inhabited dwellings. The device consists of a hemispheric capacitor with a wire mesh as the outer electrode on ground potential and the sampling substrates as the inner electrode on +7.0 kV. Negatively charged and neutral thoron decay products are accelerated to and deposited on the sampling substrates. As sampling substrates, CR39 solid-state nuclear track detectors are used in order to record the alpha decay of the sampled decay products. Nuclide discrimination is achieved by covering the detectors with aluminum foil of different thickness, which are penetrated only by alpha particles with sufficient energy. Devices of this type were calibrated against working level monitors in a thoron experimental house. The sensitivity was measured as 9.2 tracks per Bq/m{sup 3} × d of thoron decay products. The devices were used over 8 weeks in several houses built of earthen material in southern Germany, where equilibrium equivalent concentrations of 1.4–9.9 Bq/m{sup 3} of thoron decay products were measured.

  18. Measurements of voltage current characteristics of a plasma needle and its effect on plant cells

    NASA Astrophysics Data System (ADS)

    Puac, N.; Petrovic, Z. Lj; Malovic, G.; Dordevic, A.; Zivkovic, S.; Giba, Z.; Grubisic, D.

    2006-08-01

    In this paper we present voltage-current-power characteristics of a plasma needle operating in the flow of helium at atmospheric pressure. In addition, we show some examples of how such a plasma affects plant tissues. In the characterization of the plasma needle, current and voltage waveforms were recorded by two derivative probes. These two probes are similar to the probes previously used by Puac et al for measuring transmitted power in low pressure CCP rf discharge. The instantaneous power was calculated from current and voltage waveforms and U-I characteristics of the discharge were determined. Regimes of operation with and without the grounding ring at the tip of the needle were considered. We have chosen two model systems to study the effect of the plasma needle on plant cells and tissues: sweet fern gametophyte (prothallus) and calli produced in vitro. Since the prothallus consists of a single layer of cells, the cytological effects could be easily examined. In addition, calli and prothallus are easy to manipulate and in vitro culture provides a possibility to work under constant and controlled conditions.

  19. High-voltage space-plasma interactions measured on the PASP Plus test arrays

    NASA Technical Reports Server (NTRS)

    Guidice, Donald A.

    1995-01-01

    The Photovoltaic Array Space Power Plus Diagnostics (PASP Plus) experiment was developed by the Air Force's Phillips Laboratory with support from NASA's Lewis Research Center. It was launched on the Advanced Photovoltaic and Electronics EXperiments (APEX) satellite on August 3, 1994 into a 70 degree inclination, 363 km by 2550 km elliptical orbit. This orbit allows the investigation of space plasma effects on high-voltage operation (leakage current at positive voltages and arcing at negative voltages) in the perigee region. PASP Plus is testing twelve solar arrays. There are four planar Si arrays: an old standard type (used as a reference), the large-cell Space Station Freedom (SSF) array, a thin 'APSA' array, and an amorphous Si array. Next are three GaAs on Ge planar arrays and three new material planar arrays, including InP and two multijunction types. Finally, there are two concentrator arrays: a reflective-focusing Mini-Cassegrainian and a Fresnel-lens focusing Mini-Dome. PASP Plus's diagnostic sensors include: Langmuir probe to measure plasma density, an electrostatic analyzer (ESA) to measure the 30 eV to 30 KeV electron/ion spectra and determine vehicle negative potential during positive biasing, and a transient pulse monitor (TPM) to characterize the arcs that occur during the negative biasing. Through positive biasing of its test arrays, PASP Plus investigated the snapover phenomenon, which took place over the range of +100 to +300 V. It was found that array configurations where the interconnects are shielded from the space plasma (i.e., the concentrators or arrays with 'wrap-through' connectors) have lower leakage current. The concentrators exhibited negligible leakage current over the whole range up to +500 V. In the case of two similar GaAs on Ge arrays, the one with 'wrap-through' connectors had lower leakage current than the one with conventional interconnects. Through negative biasing, PASP Plus investigated the arcing rates of its test arrays. The standard Si array, with its old construction (exposed rough-surface interconnects), arced significantly over a wide voltage and plasma-density range. The other arrays arced at very low rates, mostly at voltages greater than -350 V and plasma densities near or greater than 10(exp 5)/cm(exp -3). AS expected according to theory, arcing was more prevalent when array temperatures were cold (based on biasing in eclipse).

  20. High performance cermet electrodes

    DOEpatents

    Isenberg, Arnold O. (Forest Hills Boro, PA); Zymboly, Gregory E. (Penn Hills, PA)

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  1. Modeling the measurements of cellular fluxes in microbioreactor devices using thin enzyme electrodes

    PubMed Central

    Velkovsky, Momchil; Snider, Rachel; Wikswo, John P.

    2013-01-01

    An analytic approach to the modeling of stop-flow amperometric measurements of cellular metabolism with thin glucose oxidase and lactate oxidase electrodes would provide a mechanistic understanding of the various factors that affect the measured signals. We divide the problem into two parts: (1) analytic formulas that provide the boundary conditions for the substrate and the hydrogen peroxide at the outer surface of the enzyme electrode layers and the electrode current expressed through these boundary conditions, and (2) a simple diffusion problem in the liquid compartment with the provided boundary conditions, which can be solved analytically or numerically, depending on the geometry of the compartment. The current in an amperometric stop-flow measurement of cellular glucose or lactate consumption/excretion is obtained analytically for two geometries, corresponding to devices developed at the Vanderbilt Institute for Integrative Biosystems Research and Education: a multianalyte nanophysiometer with effective one-dimensional diffusion and a multianalyte microphysiometer, for which plentiful data for metabolic changes in cells are available. The data are calibrated and fitted with the obtained time dependences to extract several cellular fluxes. We conclude that the analytical approach is applicable to a wide variety of measurement geometries and flow protocols. PMID:24031115

  2. Improved chemically amplified photoresist characterization using interdigitated electrode sensors: photoacid diffusivity measurements

    NASA Astrophysics Data System (ADS)

    Berger, Cody M.; Henderson, Clifford L.

    2004-05-01

    The ability of interdigitated electrodes to serve as novel chemically amplified resist characterization tools has recently been demonstrated through their ability to measure the Dill C kinetic rate constant for photoacid generation. The work presented in this paper attempts to further extend the capabilities of the interdigitated electrode (IDE) sensors by investigating their potential use as a measurement tool for photoacid diffusion coefficients. Impedance spectroscopy of chemically amplified photoresist coated interdigitated electrodes is used to calculate the bulk ionic conductivity of the resist film. The ionic conductivity is subsequently utilized in the Nernst-Einstein equation to calculate the diffusion coefficient of the photoacid, assuming that it is the major charge carrying species in the film. A detailed description of the measurement and data analysis processes required to calculate the diffusion coefficient of triphenylsulfonium triflate in poly(p-hydroxystyrene) is provided. In addition, the effect of varying the relative humidity of the measurement environment upon the impedance data collected has been examined. It has been observed that the presence of water within the resist film, typically as a result of absorption of water from the humid ambient environment, dramatically changes the conductivity of the resist coated IDE. This change is apparently the result of changes in the proton conduction mechanism within the resist as a function of film water content. A discussion of several possible causes of this phenomena and its impact on the interpretation of the electrical data and the calculation and meaning of an acid diffusion coefficient are presented.

  3. Gold Electrodes Modified with Self-Assembled Monolayers for Measuring L-Ascorbic Acid: An Undergraduate Analytical Chemistry Laboratory Experiment

    ERIC Educational Resources Information Center

    Ito, Takashi; Perera, D. M. Neluni T.; Nagasaka, Shinobu

    2008-01-01

    This article describes an undergraduate electrochemistry laboratory experiment in which the students measure the L-ascorbic acid content of a real sample. Gold electrodes modified with self-assembled monolayers (SAMs) of thioctic acid and cysteamine are prepared to study the effects of surface modification on the electrode reaction of L-ascorbic…

  4. Liquid electrode

    DOEpatents

    Ekechukwu, Amy A. (Augusta, GA)

    1994-01-01

    A dropping electrolyte electrode for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions.

  5. Investigation Of The EMF Versus State Of Charge Behavior Of Individual Electrodes In New And Cycled Sony 18650 HC Cells

    NASA Astrophysics Data System (ADS)

    Dudley, G.; Mattle, T.

    2011-10-01

    Individual electrode EMFs of new and cycled Sony 18650 HC cells have been measured with the help of a lithium reference electrode inserted into complete cells. Results have revealed the relative contribution of each electrode to voltage hysteresis (the difference in cell EMF between charge and discharge at the same state of charge).They have also shown changes to the shape of the positive electrode EMF versus state of charge in cycled compared to beginning of life cells.

  6. Determination of the characteristic parameters of Au/PVDF/n-InP Schottky structure from current-voltage and capacitance-voltage measurements

    NASA Astrophysics Data System (ADS)

    Padma, R.; Reddy, V. Rajagopal

    2015-06-01

    The effect of polyvinylidene fluoride (PVDF) polymer interlayer on the rectifying junction parameters of Au/n-InP Schottky diode have been investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. Experimental results show that Au/PVDF/n-InP structure exhibits a good rectifying behavior. The calculated barrier heights (BHs) are 0.73 eV (I-V), 0.88 eV (C-V) for Au/PVDF/n-InP Schottky diode, respectively. The values of the barrier height, ideality factors and series resistance estimated by I-V and Cheung's methods are compared. The discrepancy between barrier heights estimated from I-V and C-V methods is also explained.

  7. Small-Scale and Low Cost Electrodes for "Standard" Reduction Potential Measurements

    ERIC Educational Resources Information Center

    Eggen, Per-Odd; Kvittingen, Lise

    2007-01-01

    The construction of three simple and inexpensive electrodes, hydrogen, and chlorine and copper electrode is described. This simple method will encourage students to construct their own electrode and better help in understanding precipitation and other electrochemistry concepts.

  8. Teaching pH Measurements with a Student-Assembled Combination Quinhydrone Electrode

    ERIC Educational Resources Information Center

    Scholz, Fritz; Steinhardt, Tim; Kahlert, Heike; Porksen, Jens R.; Behnert, Jurgen

    2005-01-01

    A simple combination pH electrode consisting of a solid-state quinhydrone sensor and a solid-state quinhydrone reference electrode is described. Both electrodes are essentially rubber stoppers that are inserted into a special doublewalled holder.

  9. High frequency reference electrode

    DOEpatents

    Kronberg, J.W.

    1994-05-31

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or halo' at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes. 4 figs.

  10. High frequency reference electrode

    DOEpatents

    Kronberg, James W. (Aiken, SC)

    1994-01-01

    A high frequency reference electrode for electrochemical experiments comprises a mercury-calomel or silver-silver chloride reference electrode with a layer of platinum around it and a layer of a chemically and electrically resistant material such as TEFLON around the platinum covering all but a small ring or "halo" at the tip of the reference electrode, adjacent to the active portion of the reference electrode. The voltage output of the platinum layer, which serves as a redox electrode, and that of the reference electrode are coupled by a capacitor or a set of capacitors and the coupled output transmitted to a standard laboratory potentiostat. The platinum may be applied by thermal decomposition to the surface of the reference electrode. The electrode provides superior high-frequency response over conventional electrodes.

  11. In vivo impedance spectroscopy of deep brain stimulation electrodes

    NASA Astrophysics Data System (ADS)

    Lempka, Scott F.; Miocinovic, Svjetlana; Johnson, Matthew D.; Vitek, Jerrold L.; McIntyre, Cameron C.

    2009-08-01

    Deep brain stimulation (DBS) represents a powerful clinical technology, but a systematic characterization of the electrical interactions between the electrode and the brain is lacking. The goal of this study was to examine the in vivo changes in the DBS electrode impedance that occur after implantation and during clinically relevant stimulation. Clinical DBS devices typically apply high-frequency voltage-controlled stimulation, and as a result, the injected current is directly regulated by the impedance of the electrode-tissue interface. We monitored the impedance of scaled-down clinical DBS electrodes implanted in the thalamus and subthalamic nucleus of a rhesus macaque using electrode impedance spectroscopy (EIS) measurements ranging from 0.5 Hz to 10 kHz. To further characterize our measurements, equivalent circuit models of the electrode-tissue interface were used to quantify the role of various interface components in producing the observed electrode impedance. Following implantation, the DBS electrode impedance increased and a semicircular arc was observed in the high-frequency range of the EIS measurements, commonly referred to as the tissue component of the impedance. Clinically relevant stimulation produced a rapid decrease in electrode impedance with extensive changes in the tissue component. These post-operative and stimulation-induced changes in impedance could play an important role in the observed functional effects of voltage-controlled DBS and should be considered during clinical stimulation parameter selection and chronic animal research studies.

  12. Spectral response of atmospheric electric field measurements near AC high voltage power lines

    NASA Astrophysics Data System (ADS)

    Silva, H. G.; Matthews, J. C.; Wright, M. D.; Shallcross, D. E.

    2015-10-01

    To understand the influence of corona ion emission on the atmospheric electrical field, measurements were made near to two AC high voltage power lines. A JCI 131 field-mill recorded the atmospheric electric field over one year. Meteorological measurements were also taken. The data series is divided in four zones (dependent on wind direction): whole zones, Z0; zone 1, Z1; zone 2, Z2; zone 3, Z3. Z3 is the least affected by corona ion emission and for that reason it is used as a reference against Z1 and Z2, which are strongly influenced by this phenomena. Analysis was undertaken for all weather days and dry days only. The Lomb-Scargle strategy developed for unevenly spaced time-series is used to calculate the spectral response of the aforementioned zones. Only frequencies above 1 minute are considered.

  13. Multiple Input Electrode Gap Control During Vacuum Arc Remelting

    SciTech Connect

    Beaman, J.J.; Hysinger, C.L.; Melgaard, D.K.; Williamson, R.L.

    1999-01-14

    Accurate control of the electrode gap in a vacuum arc remelting (VAR) furnace has been a goal of melters for many years. The size of the electrode gap has a direct influence on ingot solidification structure. At the high melting currents (30 to 40 kA) typically used for VAR of segregation insensitive Ti and Zr alloys, process voltage is used as an indicator of electrode gap, whereas drip-short frequency (or period) is usually used at the lower currents (5 to 8 kA) employed during VAR of superalloys. Modem controllers adjust electrode position or drive velocity to maintain a voltage or drip-short frequency (or period) set-point. Because these responses are non-linear functions of electrode gap and melting current, these controllers have a limited range for which the feedback gains are valid. Models are available that relate process voltage and drip-short frequency to electrode gap. These relationships may be used to linearize the controller feedback signal. An estimate of electrode gap may then be obtained by forming a weighted sum of the independent gap estimates obtained from the voltage and drip-short signals. By using multiple independent measures to estimate the gap, a controller that is less susceptible to process disturbances can be developed. Such a controller was designed, built and tested. The tests were carried out at Allvac Corporation during VAR of 12Cr steel at intermediate current levels.

  14. Measuring of the nonlocal EDF of penning electrons by the wall electrode in the plasma afterglow

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Anatoly; Kapustin, Kirill; Sayfutdinov, Almaz

    2014-10-01

    In was patented ionization detector for gas analysis, based on the method of collisional electron spectroscopy (CES), which allows working at a high gas pressure. The CES method provides an opportunity to analyze energy of nonlocal electrons released during Penning ionization of atomic or molecular impurities by metastable helium atoms. In this case, the EDF of fast electrons will be narrow peaks that correspond to the energies of their appearance in Penning ionization. To realize the CES method at high (atmospheric) pressure the plasma gap must be small L < 0.1 mm. In this condition the traditional Langmuir probe is impossible to use for measuring the EDF. To overcome this difficulty in was proposed to use afterglow plasma and one of the electrodes as a measuring probe for the registration of EDF of fast penning electrons. In this paper we simulate the afterglow of argon discharge between parallel electrodes and show that EDF and electron sources of Penning ionization are determined by the first derivative of the current to the wall electrode with respect to potential. This work was supported by RSCF and SPbSU.

  15. A Comparison of Two Sensors Used to Measure High-Voltage, Fast-Risetime Signals in Coaxial Cable

    NASA Astrophysics Data System (ADS)

    Farr, Everett G.; Atchley, Lanney M.; Ellibee, Donald E.; Carey, William J.; Altgilbers, Larry L.

    We consider here two sensors that are commonly used to measure high-voltage fast-risetime signals in coaxial cable. One sensor measures the current in the cable, and is called a Current-Viewing Resistor, or CVR. In this design, the cable jacket is cut, a portion of the cable jacket is removed, and a number of resistors are inserted in parallel across the gap, thereby creating a low resistance in series with the outer cable jacket. The voltage across these resistors is proportional to the current in the coax. The second sensor measures the derivative of the voltage in the coax. It is fabricated from a "sawed-off" SMA connector that is inserted through a small hole in the cable jacket. In this paper we characterize the accuracy of both sensors when used with RG-220 cable, and we discuss the situations when one might prefer one measurement type over the other.

  16. Effect of current compliance and voltage sweep rate on the resistive switching of HfO{sub 2}/ITO/Invar structure as measured by conductive atomic force microscopy

    SciTech Connect

    Wu, You-Lin Liao, Chun-Wei; Ling, Jing-Jenn

    2014-06-16

    The electrical characterization of HfO{sub 2}/ITO/Invar resistive switching memory structure was studied using conductive atomic force microscopy (AFM) with a semiconductor parameter analyzer, Agilent 4156C. The metal alloy Invar was used as the metal substrate to ensure good ohmic contact with the substrate holder of the AFM. A conductive Pt/Ir AFM tip was placed in direct contact with the HfO{sub 2} surface, such that it acted as the top electrode. Nanoscale current-voltage (I-V) characteristics of the HfO{sub 2}/ITO/Invar structure were measured by applying a ramp voltage through the conductive AFM tip at various current compliances and ramp voltage sweep rates. It was found that the resistance of the low resistance state (RLRS) decreased with increasing current compliance value, but resistance of high resistance state (RHRS) barely changed. However, both the RHRS and RLRS decreased as the voltage sweep rate increased. The reasons for this dependency on current compliance and voltage sweep rate are discussed.

  17. Access resistance of stimulation electrodes as a function of electrode proximity to the retina

    NASA Astrophysics Data System (ADS)

    Majdi, Joseph A.; Minnikanti, Saugandhika; Peixoto, Nathalia; Agrawal, Anant; Cohen, Ethan D.

    2015-02-01

    Objective. Epiretinal prostheses seek to effectively stimulate the retina by positioning electrode arrays close to its surface so current pulses generate narrow retinal electric fields. Our objective was to evaluate the use of the electrical impedance of insulated platinum electrodes as a measure of the proximity of insulated platinum electrodes to the inner surface of the retina. Approach. We examined the impedance of platinum disk electrodes, 0.25 mm in diameter, insulated with two widths (0.8 and 1.6 mm outer diameter) of transparent fluoropolymer in a rabbit retinal eyecup preparation. Optical coherence tomography measured the electrode’s proximity to the retinal surface which was correlated with changes in the voltage waveform at the electrode. Electrode impedance changes during retinal deformation were also studied. Main results. When the 1.6 mm diameter insulated electrodes advanced towards the retinal surface from 1000 ?m, their voltage step at current pulse onset increased, reflecting an access resistance increase of 3880 ± 630 ?, with the 50% midpoint averaging 30 ?m, while thin 0.8 mm insulated electrode advancement showed an access resistance increase 50% midpoint averaging 16 ?m. Using impedance spectroscopy, electrode-retina proximity differences were seen in the 1.6 mm insulated electrode impedance modulus between 1 and 100 kHz and the waveform phase angle at 0.3-10 kHz, while thin 0.8 mm insulated electrode advancement produced smaller impedance modulus changes with retinal proximity between 3 and 100 kHz. These impedance changes with retinal proximity may reflect different sized zones of eye wall being coupled in series with the insulated platinum electrode. Significance. The proximity of stimulus electrodes to neural tissue in fluid-filled spaces can be estimated from access resistance changes in the stimulus pulse waveform. Because many prosthetic devices allow back telemetry communication of the stimulus electrode waveform, it is possible these series resistance increases observed with retinal proximity could be used as a metric of stimulus electrode placement.

  18. Measurements of induced voltages and currents in a distribution power line and associated atmospheric parameters

    NASA Technical Reports Server (NTRS)

    Santiago-Perez, Julio

    1988-01-01

    The frequency and intensity of thunderstorms around the Kennedy Space Center (KSC) has affected scheduled launch, landing, and other ground operations for many years. In order to protect against and provide safe working facilities, KSC has performed and hosted several studies on lightning phenomena. For the reasons mentioned above, KSC has established the Atmospheric Science Field Laboratory (ASFL). At these facilities KSC launches wire-towing rockets into thunderstorms to trigger natural lightning to the launch site. A program named Rocket Triggered Lightning Program (RTLP) is being conducted at the ASFL. This report calls for two of the experiments conducted in the summer 1988 Rocket Triggered Lightning Program. One experiment suspended an electric field mill over the launching areas from a balloon about 500 meters high to measure the space charges over the launching area. The other was to connect a waveform recorder to a nearby distribution power line to record currents and voltages wave forms induced by natural and triggered lightning.

  19. A timing detector with pulsed high-voltage power supply for mass measurements at CSRe

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Tu, X. L.; Wang, M.; Zhang, Y. H.; Xu, H. S.; Litvinov, Yu. A.; Blaum, K.; Chen, X. C.; Hu, Z. G.; Huang, W. J.; Ma, X. W.; Mao, R. S.; Mei, B.; Shuai, P.; Sun, B. H.; Yamaguchi, T.; Xia, J. W.; Xiao, G. Q.; Xu, X.; Yan, X. L.; Yang, J. C.; Yuan, Y. J.; Zhou, X. H.; Zhao, H. W.; Zhao, T. C.

    2014-08-01

    Accuracy of nuclear mass measurements in storage rings depends critically on the accuracy with which the revolution times of stored ions can be obtained. In such experiments, micro-channel plates (MCP) are used as timing detectors. Due to large phase space of injected secondary beams, a large number of ions cannot be stored in the ring and is lost within the first few revolutions. However, these ions interact with the detector and can saturate the MCP and thus deteriorate its performance. In order to eliminate such effects, a fast, pulsed high-voltage power supply (PHVPS) has been employed which keeps the detector switched-off during the first few revolutions. The new detector setup was taken into operation at the Experimental Cooler-Storage-Ring CSRe in Lanzhou and resulted in a significant improvement of the detector amplitude and efficiency characteristics.

  20. Locating of normal transitions in a Bi2223 high temperature superconducting coil by non-contact voltage measurement method

    NASA Astrophysics Data System (ADS)

    Nanato, N.; Nishiyama, K.

    2015-12-01

    Locating of normal transitions in high temperature superconducting (HTS) coils is important for protection and safety design of HTS apparatus. A general method to locate the normal transitions is to measure resistive voltages along HTS windings by many voltage taps directly soldered to the HTS coils. However, electrical insulation characteristics of the HTS coils are deteriorated because it is necessary to remove electrical insulations of the HTS wires for the soldering. It is a serious problem especially for AC HTS coils to which high voltages are applied. Therefore the authors have presented a non-contact voltage measurement method that can detect the resistive voltages without removing the insulations by voltage dividing capacitors. So far the authors have verified the principle of the non-contact method. In this paper, a method to locate the normal transitions in a Bi2223 HTS coil based on the non-contact method is proposed. The proposed method can not only detect the normal transitions but also locate their positions. It is experimentally confirmed that the proposed method is useful for locating the normal transitions.

  1. Focused ion beam processing to fabricate ohmic contact electrodes on a bismuth nanowire for Hall measurements

    PubMed Central

    2013-01-01

    Ohmic contact electrodes for four-wire resistance and Hall measurements were fabricated on an individual single-crystal bismuth nanowire encapsulated in a cylindrical quartz template. Focused ion beam processing was utilized to expose the side surfaces of the bismuth nanowire in the template, and carbon and tungsten electrodes were deposited on the bismuth nanowire in situ to achieve electrical contacts. The temperature dependence of the four-wire resistance was successfully measured for the bismuth nanowire, and a difference between the resistivities of the two-wire and four-wire methods was observed. It was concluded that the two-wire method was unsuitable for estimation of the resistivity due to the influence of contact resistance, even if the magnitude of the bismuth nanowire resistance was greater than the kilo-ohm order. Furthermore, Hall measurement of a 4-?m-diameter bismuth microwire was also performed as a trial, and the evaluated temperature dependence of the carrier mobility was in agreement with that for bulk bismuth, which indicates that the carrier mobility was successfully measured using this technique. PACS 81.07.Gf PMID:24070421

  2. Temperature-dependent property measurements on multi-electroded thin-layer dielectrics

    SciTech Connect

    Tani, T.; Xu, Z.; Moses, P.; Payne, D.A. )

    1994-06-01

    A measurement system was designed and assembled for the automatic collection of electrical data for thin-layer dielectrics as a function of temperature. The dielectrics were deposited on platinized silicon by sol-gel processing, and the dielectric thickness was 0.2--0.4 [mu]m. Many ([gt]25) surface electrodes were formed by sputtering gold through a shadow mark, with a typical electrode size of 210[times]210 [mu]m[sup 2]. The measurement equipment was computer controlled, with three-axis digital stepping motors that could scan multi-electroded capacitors and collect statistically meaningful data. The temperature-dependent properties were measured between [minus]100 and 300 [degree]C as a function of frequency (100 Hz to 1 MHz) and applied field strength (0--50 MV/m). Data are reported for sol-gel-derived BaTiO[sub 3], PbZrO[sub 3], and (Pb,La)(Zr,Ti)O[sub 3] (i.e., PLZT) thin-layer capacitors. Capacitance values were typically 500--1000 pF, and the dielectric constant could be determined within a standard deviation of [plus minus]1.3%. Nanocrystalline BaTiO[sub 3] was found to have a dielectric constant of 210 at room temperature with no ferroelectric properties or dielectric anomalies between [minus]80 and 200 [degree]C. Antiferroelectric PbZrO[sub 3] had characteristic field-forced phase transformation behavior to the ferroelectric state with increasing bias. The field-induced polarization was approximately 300 mC/m[sup 2] and the coercive field was 22--28 MV/m. PLZT 8/65/35 had a dielectric constant of 556[plus minus]7 at 25 [degree]C, 100 KHz, and 50 mV.

  3. Time varying voltage combustion control and diagnostics sensor

    DOEpatents

    Chorpening, Benjamin T. (Morgantown, WV); Thornton, Jimmy D. (Morgantown, WV); Huckaby, E. David (Morgantown, WV); Fincham, William (Fairmont, WV)

    2011-04-19

    A time-varying voltage is applied to an electrode, or a pair of electrodes, of a sensor installed in a fuel nozzle disposed adjacent the combustion zone of a continuous combustion system, such as of the gas turbine engine type. The time-varying voltage induces a time-varying current in the flame which is measured and used to determine flame capacitance using AC electrical circuit analysis. Flame capacitance is used to accurately determine the position of the flame from the sensor and the fuel/air ratio. The fuel and/or air flow rate (s) is/are then adjusted to provide reduced flame instability problems such as flashback, combustion dynamics and lean blowout, as well as reduced emissions. The time-varying voltage may be an alternating voltage and the time-varying current may be an alternating current.

  4. Polysulfide transport through separators measured by a linear voltage sweep method

    NASA Astrophysics Data System (ADS)

    Cui, Yi; Fu, Yongzhu

    2015-07-01

    Shuttle of polysulfide from the sulfur cathode to lithium metal anode in rechargeable lithium-sulfur batteries is a critical issue hindering cycling efficiency and life. Several approaches have been developed to minimize it including polysulfide-blocking separators; there is a need for measuring polysulfide transport through separators. We here show a linear voltage sweep method to measure anodic (oxidization) current of polysulfide crossed separators, which can be used as a quantitative measurement of the polysulfide transport. The electrochemical oxidation of polysulfide is diffusion controlled. The electrical charge in Coulombs produced by the oxidation of polysulfide is linearly related to the concentration of polysulfide within a certain range (?0.5 M). Separators with a high porosity (large pore size) show high anodic currents, resulting in fast capacity degradation and low Coulombic efficiencies in Li-S cells. These results demonstrate this method can be used to correlate the polysulfide transport through separators with the separator structure and battery performance, therefore provide guidance for developing new separators for lithium-sulfur batteries.

  5. Low voltage shocks have a significantly higher tilt of the internal electric field than do high voltage shocks.

    PubMed

    Brewer, J E; Tvedt, M A; Adams, T P; Kroll, M W

    1995-01-01

    Typically, an implantable cardioverter defibrillator (ICD) uses a cardioversion shock that is a lower voltage pulse of the same morphology and tilt as its defibrillation pulse. We investigated the internal electric field resulting from an ICD low voltage shock to determine whether its field characteristics matched those of the internal electric field of a high voltage shock. We attached epicardial patch electrodes, for shock delivery, to five fresh pig hearts placed in a diluted, heparinized saline bath. We inserted two plunge electrodes into the myocardium to measure an internal voltage proportional to the electric field. Monophasic 20-msec shocks, from a 140-microF capacitor, ranging from 0.1-30 joules, were delivered through the patches. We measured the current, external voltage, and internal voltage every 0.1 msec throughout the duration of a shock. For each shock, we calculated the time point that represented the 65% tilt position as measured across the patch electrodes. At this 65% tilt time position, we measured the pulse widths and calculated the internal tilt from the internal voltage. We found that the initial internal voltage for the 30-joule shock was 173 +/- 40 volts compared to 10 +/- 2 volts for the 0.1-joule shock. Similarly, we found that the final internal voltage for the 30-joule shock was 56 +/- 14 volts compared to 2 +/- 1 volts for the 0.1-joule shock. Thus, the internal tilt for the 30-joule shock was 68 +/- 1% versus 82 +/- 3% for the 0.1-joule shock (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7724402

  6. An electric field in nanosecond surface dielectric barrier discharge at different polarities of the high voltage pulse: spectroscopy measurements and numerical modeling

    NASA Astrophysics Data System (ADS)

    Stepanyan, S. A.; Soloviev, V. R.; Starikovskaia, S. M.

    2014-12-01

    The ratio of emission intensities of the second positive N2(C3?u, v? = 0) ? N2(B3?g, v = 0), 337.1 nm and first negative \\text{N}2+ (B2?g+,v\\prime =0) ? \\text{N}2+ (X2?g+,v=0) , 391.4 nm systems of nitrogen have been measured in a nanosecond surface dielectric barrier discharge (SDBD). The measurements were carried out in synthetic air for a pressure range 1-3 bar for different polarities of the high-voltage (HV) pulse. For all the investigated conditions, the ratio of emission intensities at the wavelengthes 391.4 and 337.1 nm, measured experimentally, R391/337\\text{exp} is systematically higher for the positive polarity of HV electrodes. To analyze the spatial distribution of N2(C3?u) and \\text{N}2+ (B2?g+) emissions, comprehensive two-dimensional numerical modeling for P = 1 bar has been performed. The details of the formation of a narrow gap between the dielectric surface and the streamer channel in the case of positive polarity of HV electrodes are discussed. The ratio of integrated over space calculated emission intensities, R391/337\\text{th} , has been analyzed and compared with obtained experimental data. A good agreement was obtained for a negative polarity SDBD. For a positive polarity discharge, R391/337\\text{exp}\\gg R391/337\\text{th} for all the considered conditions. Explanation for the observed effect is suggested.

  7. Charge-pump voltage converter

    DOEpatents

    Brainard, John P. (Albuquerque, NM); Christenson, Todd R. (Albuquerque, NM)

    2009-11-03

    A charge-pump voltage converter for converting a low voltage provided by a low-voltage source to a higher voltage. Charge is inductively generated on a transfer rotor electrode during its transit past an inductor stator electrode and subsequently transferred by the rotating rotor to a collector stator electrode for storage or use. Repetition of the charge transfer process leads to a build-up of voltage on a charge-receiving device. Connection of multiple charge-pump voltage converters in series can generate higher voltages, and connection of multiple charge-pump voltage converters in parallel can generate higher currents. Microelectromechanical (MEMS) embodiments of this invention provide a small and compact high-voltage (several hundred V) voltage source starting with a few-V initial voltage source. The microscale size of many embodiments of this invention make it ideally suited for MEMS- and other micro-applications where integration of the voltage or charge source in a small package is highly desirable.

  8. Radio frequency cavity analysis, measurement, and calibration of absolute Dee voltage for K-500 superconducting cyclotron at VECC, Kolkata

    SciTech Connect

    Som, Sumit; Seth, Sudeshna; Mandal, Aditya; Paul, Saikat; Duttagupta, Anjan

    2013-02-15

    Variable Energy Cyclotron Centre has commissioned a K-500 superconducting cyclotron for various types of nuclear physics experiments. The 3-phase radio-frequency system of superconducting cyclotron has been developed in the frequency range 9-27 MHz with amplitude and phase stability of 100 ppm and {+-}0.2{sup 0}, respectively. The analysis of the RF cavity has been carried out using 3D Computer Simulation Technology (CST) Microwave Studio code and various RF parameters and accelerating voltages ('Dee' voltage) are calculated from simulation. During the RF system commissioning, measurement of different RF parameters has been done and absolute Dee voltage has been calibrated using a CdTe X-ray detector along with its accessories and known X-ray source. The present paper discusses about the measured data and the simulation result.

  9. Shielded button electrodes for time-resolved measurements of electron cloud buildup

    NASA Astrophysics Data System (ADS)

    Crittenden, J. A.; Billing, M. G.; Li, Y.; Palmer, M. A.; Sikora, J. P.

    2014-06-01

    We report on the design, deployment and signal analysis for shielded button electrodes sensitive to electron cloud buildup at the Cornell Electron Storage Ring. These simple detectors, derived from a beam-position monitor electrode design, have provided detailed information on the physical processes underlying the local production and the lifetime of electron densities in the storage ring. Digitizing oscilloscopes are used to record electron fluxes incident on the vacuum chamber wall in 1024 time steps of 100 ps or more. The fine time steps provide a detailed characterization of the cloud, allowing the independent estimation of processes contributing on differing time scales and providing sensitivity to the characteristic kinetic energies of the electrons making up the cloud. By varying the spacing and population of electron and positron beam bunches, we map the time development of the various cloud production and re-absorption processes. The excellent reproducibility of the measurements also permits the measurement of long-term conditioning of vacuum chamber surfaces.

  10. Multimegavolt voltage measurements in a PBFA II prototype water line using the electro-optic Kerr effect

    SciTech Connect

    Allen, G.R.; Davis, H.P.; Turman, B.N.; Bloomquist, D.D.; Chang, J.; Neyer, B.T.; Hebner, R.E.

    1985-01-01

    We have developed a highly accurate, non-perturbing, non-invasive voltage monitor for multimegavolt measurements in water using the electro-optic Kerr effect. Measurements have been made in various geometries at approx.2.5 MV in the water transmission line of the DEMON (PBFA-II demonstration) accelerator at Sandia. In each geometry, including flat parallel plates, tapered flat plates, coaxial line, and intermediate store capacitor, the Kerr voltage measurements are compared with those of standard V-dot probes. The accuracy of the Kerr measurements is approx.+-4%, improvable to < +-2%. The technique can be used to calibrate V-dot probes under full-voltage operating conditions. Moreover, in the presence of streamers or voltage nonuniformities (induced by switching feeds, e.g.), the Kerr measurements are more reliable and accurate than probes. In order to replace V-dot probes in a routine, multi-channel application, we are implementing the Kerr monitor on the streak-camera-based High Speed Multichannel Data Recorder.

  11. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces.

    PubMed

    Gross, Benjamin J; El-Naggar, Mohamed Y

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions. PMID:26133851

  12. A combined electrochemical and optical trapping platform for measuring single cell respiration rates at electrode interfaces

    NASA Astrophysics Data System (ADS)

    Gross, Benjamin J.; El-Naggar, Mohamed Y.

    2015-06-01

    Metal-reducing bacteria gain energy by extracellular electron transfer to external solids, such as naturally abundant minerals, which substitute for oxygen or the other common soluble electron acceptors of respiration. This process is one of the earliest forms of respiration on earth and has significant environmental and technological implications. By performing electron transfer to electrodes instead of minerals, these microbes can be used as biocatalysts for conversion of diverse chemical fuels to electricity. Understanding such a complex biotic-abiotic interaction necessitates the development of tools capable of probing extracellular electron transfer down to the level of single cells. Here, we describe an experimental platform for single cell respiration measurements. The design integrates an infrared optical trap, perfusion chamber, and lithographically fabricated electrochemical chips containing potentiostatically controlled transparent indium tin oxide microelectrodes. Individual bacteria are manipulated using the optical trap and placed on the microelectrodes, which are biased at a suitable oxidizing potential in the absence of any chemical electron acceptor. The potentiostat is used to detect the respiration current correlated with cell-electrode contact. We demonstrate the system with single cell measurements of the dissimilatory-metal reducing bacterium Shewanella oneidensis MR-1, which resulted in respiration currents ranging from 15 fA to 100 fA per cell under our measurement conditions. Mutants lacking the outer-membrane cytochromes necessary for extracellular respiration did not result in any measurable current output upon contact. In addition to the application for extracellular electron transfer studies, the ability to electronically measure cell-specific respiration rates may provide answers for a variety of fundamental microbial physiology questions.

  13. Liquid electrode

    DOEpatents

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  14. Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

    PubMed

    Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

    2015-10-20

    Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 ?m apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration. PMID:26375039

  15. Simultaneous measurements of wire electrode surface contamination and corona discharge characteristics in an air-cleaning electrostatic precipitator

    SciTech Connect

    Kanazawa, Seiji; Ohkubo, Toshikazu; Nomoto, Yukiharu; Adachi, Takayoshi; Chang, J.S.

    1997-01-01

    Contamination of the corona wire in a wire-to-plate type air-cleaning electrostatic precipitator is studied experimentally. In order to enhance the contamination of wire, air containing dusts is directly supplied to a part of the wire electrode. Spores of Lycopodium and cigarette smoke particles are used as test dusts. Simultaneous measurements of wire electrode optical images and corona discharge modes are carried out during contamination processes. Results show that corona discharge modes and optical emission from the wire electrode change with time due to the surface contamination. In the case of cigarette smoke, after a time elapsed, streamer coronas appear due to the buildup of smoke particles on the wire surface. After the first streamer generation, the corona current fluctuates with time because the formation and diminution of the projections occur alternately at the different parts on the wire electrode surface.

  16. Quantitative Measurement of Transmitters in Individual Vesicles in the Cytoplasm of Single Cells with Nanotip Electrodes.

    PubMed

    Li, Xianchan; Majdi, Soodabeh; Dunevall, Johan; Fathali, Hoda; Ewing, Andrew G

    2015-10-01

    The quantification of vesicular transmitter content is important for studying the mechanisms of neurotransmission and malfunction in disease, and yet it is incredibly difficult to measure the tiny amounts of neurotransmitters in the attoliter volume of a single vesicle, especially in the cell environment. We introduce a novel method, intracellular vesicle electrochemical cytometry. A nanotip conical carbon-fiber microelectrode was used to electrochemically measure the total content of electroactive neurotransmitters in individual nanoscale vesicles in single PC12 cells as these vesicles lysed on the electrode inside the living cell. The results demonstrate that only a fraction of the quantal neurotransmitter content is released during exocytosis. These data support the intriguing hypothesis that the vesicle does not open all the way during the normal exocytosis process, thus resulting in incomplete expulsion of the vesicular contents. PMID:26266819

  17. Comparison of clinical and physical measures of image quality in chest and pelvis computed radiography at different tube voltages

    SciTech Connect

    Sandborg, Michael; Tingberg, Anders; Ullman, Gustaf; Dance, David R.; Alm Carlsson, Gudrun

    2006-11-15

    The aim of this work was to study the dependence of image quality in digital chest and pelvis radiography on tube voltage, and to explore correlations between clinical and physical measures of image quality. The effect on image quality of tube voltage in these two examinations was assessed using two methods. The first method relies on radiologists' observations of images of an anthropomorphic phantom, and the second method was based on computer modeling of the imaging system using an anthropomorphic voxel phantom. The tube voltage was varied within a broad range (50-150 kV), including those values typically used with screen-film radiography. The tube charge was altered so that the same effective dose was achieved for each projection. Two x-ray units were employed using a computed radiography (CR) image detector with standard tube filtration and antiscatter device. Clinical image quality was assessed by a group of radiologists using a visual grading analysis (VGA) technique based on the revised CEC image criteria. Physical image quality was derived from a Monte Carlo computer model in terms of the signal-to-noise ratio, SNR, of anatomical structures corresponding to the image criteria. Both the VGAS (visual grading analysis score) and SNR decrease with increasing tube voltage in both chest PA and pelvis AP examinations, indicating superior performance if lower tube voltages are employed. Hence, a positive correlation between clinical and physical measures of image quality was found. The pros and cons of using lower tube voltages with CR digital radiography than typically used in analog screen-film radiography are discussed, as well as the relevance of using VGAS and quantum-noise SNR as measures of image quality in pelvis and chest radiography.

  18. Investigation on the Corona Discharge in Blade-to-Plane Electrode Configuration

    NASA Astrophysics Data System (ADS)

    Kaci, Meziane; Ait Said, Hakim; Laifaoui, Abdelkrim; Aissou, Massinissa; Nouri, Hamou; Zebboudj, Youcef

    2015-12-01

    The aim of this work is to analyze the characteristics of the corona discharge in blade-to-plane electrode configuration. An experimental investigation has been carried out on the geometric parameters that govern the formation of both positive and negative corona discharges, such as the inter-electrode distance, the blade-to-blade spacing, and the number of the discharging blades. The current-voltage characteristics, the breakdown voltage, and the Warburg current distribution were measured. The assisted corona discharge is an example of a blade electrode discharge that can be used to reduce the operating voltage of a conventional corona discharge. The current-voltage characteristics of both positive and negative corona discharges in a blade-to-plane electrode configuration are of the Townsend's law form. The general formula proposed by Meng et al. can also be applied in this system. It has been shown that the breakdown voltage and the corona conductance are strongly affected by the inter-electrode distance. To obtain a maximum current, the blade electrodes should be distant from each other by a value of 2 a ? h. To obtain a constant value of current, the blade electrodes should be separated by a value of 2 a >> h, confirming the Cooperman's law. The current density distribution is satisfied; an exponent of 5.0 is taken for positive polarity and an exponent of 4.8 for negative polarity.

  19. Three-electrode plasma reactor for the removal of toxic gases

    NASA Astrophysics Data System (ADS)

    Gallego, J. L.; Giuliani, L.; Grondona, D.; Minotti, F.

    2015-03-01

    Electrical and spectroscopic measurement for the characterization of a novel three- electrode plasma reactor for the treatment of toxic gases is presented. The three-electrode discharge consists in a dielectric barrier discharge (DBD) combined with a corona discharge (CD). The DBD is generated by applying an alternating high voltage signal between two circular aluminium plate electrodes attached to opposite sides of a disk made of dielectric material. The CD is generated applying a continuous negative high voltage to an external cylindrical mesh electrode, coaxial with the DBD electrode system. The gap between the edge of the DBD system and the mesh electrode is approximately 20 mm wide. Up to five DBD electrode systems can be connected in parallel inside the reactor, axially separated from each other by 30 mm. The electrical characterization consisted in the measurement of the current between the DBD system and the external mesh, and the voltages of the electrodes. In order to understand the dynamics of the streamers, a theoretical determination of the laplacian electric field generated by the biased electrodes was done. Optical emission spectroscopy was performed in the range of wavelengths 280-480 nm, containing the typical spectral bands 2nd positive and 1st negative systems of molecular nitrogen.

  20. Current-Voltage Measurements for DC Microplasmas with Gap Sizes Less Than 10 ?m

    NASA Astrophysics Data System (ADS)

    Rumbach, Paul; Go, David

    2011-10-01

    Direct current (DC) microplasmas have been of great interest to the scientific community for the past decade because of their non-equilibrium characteristics and stability at atmospheric pressures. Owing to their large surface-to-volume ratio, processes occurring at the cathode surface can play a dominant role in determining many of the thermodynamic properties of a DC microplasma. Better understanding of these processes can lead to better control of thermodynamic properties, such as the electron energy distribution function. The departure from typical Paschen pressure ×distance pd-scaling for breakdown in gap sizes d < 5 ?m indicates that processes other than traditional secondary emission are producing electron current at the cathode, and ion-enhanced field emission has been identified as the main process leading to the so-called modified Paschen's curve. However, it is still unclear what other properties ion-enhanced field emission affects in addition to breakdown and its ultimate role in sustaining the microplasma. Using a classic, one-dimensional, parallel plate setup, current-voltage (iV) curves are measured for gap sizes less than 10 ?m in both pure argon and nitrogen with pressures ranging from 1 to 750 torr. Distinct features of these iV curves provide insight to the different processes occurring in DC microplasmas that separate them from their meso- (~100 ?ms) and macroscale counterparts (> 1 mm).

  1. Feasibility of using respiratory correlated mega voltage cone beam computed tomography to measure tumor motion.

    PubMed

    Chen, Mingqing; Siochi, R Alfredo

    2011-01-01

    The purpose of this study was to test the feasibility of using respiratory correlated mega voltage cone-beam computed tomography (MVCBCT), taken during patient localization, to quantify the size and motion of lung tumors. An imaging phantom was constructed of a basswood frame embedded with six different-sized spherical pieces of paraffin wax. The Quasar respiratory motion phantom was programmed to move the imaging phantom using typical respiratory motion. The moving imaging phantom was scanned using various MVCBCT imaging parameters, including two beam line types, two protocols with different ranges of rotation and different imaging doses. A static phantom was also imaged as a control. For all the 3D volumetric images, the contours of the six spherical inserts were measured manually. Compared with the nominal sphere diameter, the average relative error in the size of the respiratory correlated MVCBCT spheres ranged from 5.3% to 12.6% for the four largest spheres, ranging in size from 3.6 cc to 29 cc. Larger errors were recorded for the two smallest inserts. The average relative error in motion was 5.1% smaller than the programmed amplitude of 3.0 cm. We are able to conclude that it is feasible to use respiratory correlated MVCBCT to quantify tumor motion for lung cancer patients. PMID:21587196

  2. A Simple Hydrogen Electrode

    ERIC Educational Resources Information Center

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements

  3. Design of an Integrated Thermoelectric Generator Power Converter for Ultra-Low Power and Low Voltage Body Energy Harvesters aimed at EEG/ECG Active Electrodes

    NASA Astrophysics Data System (ADS)

    Ataei, Milad; Robert, Christian; Boegli, Alexis; Farine, Pierre-André

    2014-11-01

    This paper describes a design procedure for an efficient body thermal energy harvesting integrated power converter. This procedure is based on loss examination for a selfpowered medical device. All optimum system parameters are calculated respecting the transducer constraints and the application form factor. It is found that it is possible to optimize converter's working frequency with proper design of its pulse generator circuit. At selected frequency, it has been demonstrated that wide area voltage doubler can be eliminated at the expense of wider switches. With this method, more than 60% efficiency is achieved in simulation for just 20mV transducer output voltage and 30% of entire chip area is saved.

  4. Research and Experiments on a Unipolar Capacitive Voltage Sensor.

    PubMed

    Zhou, Qiang; He, Wei; Li, Songnong; Hou, Xingzhe

    2015-01-01

    Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid. PMID:26307992

  5. Research and Experiments on a Unipolar Capacitive Voltage Sensor

    PubMed Central

    Zhou, Qiang; He, Wei; Li, Songnong; Hou, Xingzhe

    2015-01-01

    Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid. PMID:26307992

  6. Electrode immersion depth determination and control in electroslag remelting furnace

    DOEpatents

    Melgaard, David K. (Albuquerque, NM); Beaman, Joseph J. (Austin, TX); Shelmidine, Gregory J. (Tijeras, NM)

    2007-02-20

    An apparatus and method for controlling an electroslag remelting furnace comprising adjusting electrode drive speed by an amount proportional to a difference between a metric of electrode immersion and a set point, monitoring impedance or voltage, and calculating the metric of electrode immersion depth based upon a predetermined characterization of electrode immersion depth as a function of impedance or voltage.

  7. Carrier transport and collection in fully depleted semiconductors by a combined action of the space charge field and the field due to electrode voltages

    DOEpatents

    Rehak, P.; Gatti, E.

    1987-08-18

    A semiconductor charge transport device and method for making same are disclosed, characterized by providing a thin semiconductor wafer having rectifying junctions on its opposing major surfaces and including a small capacitance ohmic contact, in combination with bias voltage means and associated circuit means for applying a predetermined voltage to effectively deplete the wafer in regions thereof between the rectifying junctions and the ohmic contact. A charge transport device of the invention is usable as a drift chamber, a low capacitance detector, or a charge coupled device each constructed according to the methods of the invention for making such devices. Detectors constructed according to the principles of the invention are characterized by having significantly higher particle position indicating resolution than is attainable with prior art detectors, while at the same time requiring substantially fewer readout channels to realize such high resolution. 16 figs.

  8. Carrier transport and collection in fully depleted semiconductors by a combined action of the space charge field and the field due to electrode voltages

    DOEpatents

    Rehak, Pavel (Patchogue, NY); Gatti, Emilio (Lesmo, IT)

    1987-01-01

    A semiconductor charge transport device and method for making same, characterized by providing a thin semiconductor wafer having rectifying junctions on its opposing major surfaces and including a small capacitance ohmic contact, in combination with bias voltage means and associated circuit means for applying a predetermined voltage to effectively deplete the wafer in regions thereof between the rectifying junctions and the ohmic contact. A charge transport device of the invention is usable as a drift chamber, a low capacitance detector, or a charge coupled device each constructed according to the methods of the invention for making such devices. Detectors constructed according to the principles of the invention are characterized by having significantly higher particle position indicating resolution than is attainable with prior art detectors, while at the same time requiring substantially fewer readout channels to realize such high resolution.

  9. Carrier transport and collection in fully depleted semiconductors by a combined action of the space charge field and the field due to electrode voltages

    DOEpatents

    Rehak, P.; Gatti, E.

    1984-02-24

    A semiconductor charge transport device and method for making same, characterized by providing a thin semiconductor wafer having rectifying functions on its opposing major surfaces and including a small capacitance ohmic contact, in combination with bias voltage means and associated circuit means for applying a predetermined voltage to effectively deplete the wafer in regions thereof between the rectifying junctions and the ohmic contact. A charge transport device of the invention is usable as a drift chamber, a low capacitance detector, or a charge coupled device each constructed according to the methods of the invention for making such devices. Detectors constructed according to the principles of the invention are characterized by having significantly higher particle position indicating resolution than is attainable with prior art detectors, while at the same time requiring substantially fewer readout channels to realize such high resolution.

  10. Voltage and Dopant Concentration Measurements of Semiconductors using a Band-Pass Toroidal Energy Analyzer Inside a Scanning Electron Microscope.

    PubMed

    Srinivasan, Avinash; Khursheed, Anjam

    2015-08-01

    This paper presents experimental results obtained from a scanning electron microscope (SEM) second-order focusing toroidal electron energy analyzer attachment. The results demonstrate that the analyzer can be used to obtain high signal-to-noise voltage and dopant concentration measurements on semiconductors in the presence of different electric field conditions at the sample. The experimentally calculated relative error of measurement typically varies from 31 to 63, corresponding to secondary electron (SE) signal mean shifts of 9-18 mV. The millivolt accuracy of these results is over one order of magnitude better than earlier quantitative dopant concentration measurements made by a retarding field analyzer. PMID:26223549

  11. Design of a platinum resistance thermometer temperature measuring transducer and improved accuracy of linearizing the output voltage

    SciTech Connect

    Malygin, V.M.

    1995-06-01

    An improved method is presented for designing a temperature measuring transducer, the electrical circuit of which comprises an unbalanced bridge, in one arm of which is a platinum resistance thermometer, and containing a differential amplifier with feedback. Values are given for the coefficients, the minimum linearization error is determined, and an example is also given of the practical design of the transducer, using the given coefficients. A determination is made of the limiting achievable accuracy in linearizing the output voltage of the measuring transducer, as a function of the range of measured temperature.

  12. In Situ Spatially and Temporally Resolved Measurements of Salt Concentration between Charging Porous Electrodes for Desalination

    E-print Network

    Santiago, Juan G.

    Porous Electrodes for Desalination by Capacitive Deionization Matthew E. Suss,, P.M. Biesheuvel Supporting Information ABSTRACT: Capacitive deionization (CDI) is an emerging water desalination technique to enable faster and more efficient desalination,8 ion exchange mem- branes along electrode surfaces

  13. ELECTRODE MEASUREMENT OF REDOX POTENTIAL IN ANAEROBIC FERRIC/FERROUS CHLORIDE SYSTEMS

    EPA Science Inventory

    The behaviour of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the Fe3+/Fe2+ couple in a Nernstian manner. A new method fo...

  14. ELECTRODE MEASUREMENT OF REDOX POTENTIAL IN ANAEROBIC FERRIC/FERROUS CHLORIDE SYSTEMS

    EPA Science Inventory

    The behavior of two inert redox electrodes (Pt and wax-impregnated graphite) was investigated in anaerobic ferrous and ferric chloride solutions in order to establish if these electrodes respond to the FE3/Fe2+ couple in a Nernstian nanner. ew method for determining dissolved fer...

  15. Measurement of high-voltage and radiation-damage limitations to advanced solar array performance

    NASA Technical Reports Server (NTRS)

    Guidice, D. A.; Severance, P. S.; Keinhardt, K. C.

    1991-01-01

    A description is given of the reconfigured Photovoltaic Array Space Power (PASP) Plus experiment: its objectives, solar-array complement, and diagnostic sensors. Results from a successful spaceflight will lead to a better understanding of high-voltage and radiation-damage limitations in the operation of new-technology solar arrays.

  16. Ultra-low power sensor for autonomous non-invasive voltage measurement in IoT solutions for energy efficiency

    NASA Astrophysics Data System (ADS)

    Villani, Clemente; Balsamo, Domenico; Brunelli, Davide; Benini, Luca

    2015-05-01

    Monitoring current and voltage waveforms is fundamental to assess the power consumption of a system and to improve its energy efficiency. In this paper we present a smart meter for power consumption which does not need any electrical contact with the load or its conductors, and which can measure both current and voltage. Power metering becomes easier and safer and it is also self-sustainable because an energy harvesting module based on inductive coupling powers the entire device from the output of the current sensor. A low cost 32-bit wireless CPU architecture is used for data filtering and processing, while a wireless transceiver sends data via the IEEE 802.15.4 standard. We describe in detail the innovative contact-less voltage measurement system, which is based on capacitive coupling and on an algorithm that exploits two pre-processing channels. The system self-calibrates to perform precise measurements regardless the cable type. Experimental results demonstrate accuracy in comparison with commercial high-cost instruments, showing negligible deviations.

  17. Dynamic Analysis of Mcfc Porous Electrode

    NASA Astrophysics Data System (ADS)

    Lee, Gwo-Lin Kevin

    1992-01-01

    The intent of this work is to develop AC impedance measurements, in combination with other methods, as a tool to determine the relative importance of various resistance sources in the multi-step process occurring at a gas-diffusion porous electrode. In particular, the case of a MCFC cathode is studied. The goals of this study are: (1) elucidation of electrode mechanism; (2) analysis of the porous electrode performance for the purpose of optimizing design; and (3) developing the capabilities of AC impedance as an index of long-term cell performance decay. The oxygen reduction reaction of molten carbonate fuel cell and the corresponding kinetic as well as transport parameters were tried to be estimated by using impedance techniques combining with other electrochemical methods from flag, wire and rotating disk electrodes in pot cell as well as porous electrode in lab cell. The dominant pathway for oxygen reduction in 62%Li _2CO_3/38%K _2CO_3 melt at 650^circC is via superoxide ions. This follows from flag electrode impedance results indicating that O_sp{2}{ -}/CO_2 mixed diffusion is the dominant source of resistance. The polarization behavior of gas-diffusion porous electrodes has been analyzed in terms of individual voltage loss and overall voltage loss. In most cases, the optimal electrolyte filling will be obtained when the dominant source of voltage loss switches from ohmic or mass transfer resistances to kinetic activation resistance, and similar behavior for optimal electrode thickness. Pressurized operation is favorable for performance if the reaction mechanism follows the superoxide mechanism, but not if the peroxide path dominates. A distributed-network approach has been developed and it is concluded that a digital simulation of AC-superimposed -on-DC impedance of a porous electrode is possible and helpful. Kinetic activation and mass transfer resistances are extracted separate and conclude that both peroxide and superoxide contribute the oxygen reduction around rest potential, but the superoxide will be the dominant reduction species under current load. CO_2 can somewhat reacts with (O)^- to form CO _sp{3}{=}, this leads CO_2 has a near zero reaction order for porous electrode. The capabilities of using AC impedance techniques for monitoring the long term cell performance is promising but needs further development.

  18. Near-wall measurements of the bubble- and Lorentz-force-driven convection at gas-evolving electrodes

    NASA Astrophysics Data System (ADS)

    Baczyzmalski, Dominik; Weier, Tom; Kähler, Christian J.; Cierpka, Christian

    2015-08-01

    Chemical energy storage systems, e.g., in the form of hydrogen or methanol, have a great potential for the establishment of volatile renewable energy sources due to the large energy density. The efficiency of hydrogen production through water electrolysis is, however, limited by gas bubbles evolving at the electrode's surface and can be enhanced by an accelerated bubble detachment. In order to characterize the complex multi-phase flow near the electrode, simultaneous measurements of the fluid velocities and the size and trajectories of hydrogen bubbles were performed in a water electrolyzer. The liquid phase velocity was measured by PIV/PTV, while shadowgraphy was used to determine the bubble trajectories. Special measurement and evaluation techniques had to be applied as the measurement uncertainty is strongly affected by the high void fraction close to the wall. In particular, the application of an advanced PTV scheme allowed for more precise fluid velocity measurements closer to electrode. Based on these data, stability characteristics of the near-wall flow were evaluated and compared to that of a wall jet. PTV was used as well to investigate the effect of Lorentz forces on the near-wall fluid velocities. The results show a significantly increased wall parallel liquid phase velocity with increasing Lorentz forces. It is presumed that this enhances the detachment of hydrogen bubbles from the electrode surface and, consequently, decreases the fractional bubble coverage and improves the efficiency. In addition, the effect of large rising bubbles with path oscillations on the near-wall flow was investigated. These bubbles can have a strong impact on the mass transfer near the electrode and thus affect the performance of the process.

  19. A multi-electrode biomimetic electrolocation sensor

    NASA Astrophysics Data System (ADS)

    Mayekar, K.; Damalla, D.; Gottwald, M.; Bousack, H.; von der Emde, G.

    2012-04-01

    We present the concept of an active multi-electrode catheter inspired by the electroreceptive system of the weakly electric fish, Gnathonemus petersii. The skin of this fish exhibits numerous electroreceptor organs which are capable of sensing a self induced electrical field. Our sensor is composed of a sending electrode and sixteen receiving electrodes. The electrical field produced by the sending electrode was measured by the receiving electrodes and objects were detected by the perturbation of the electrical field they induce. The intended application of such a sensor is in coronary diagnostics, in particular in distinguishing various types of plaques, which are major causes of heart attack. For calibration of the sensor system, finite element modeling (FEM) was performed. To validate the model, experimental measurements were carried out with two different systems. The physical system was glass tubing with metal and plastic wall insertions as targets. For the control of the experiment and for data acquisition, the software LabView designed for 17 electrodes was used. Different parameters of the electric images were analyzed for the prediction of the electrical properties and size of the inserted targets in the tube. Comparisons of the voltage modulations predicted from the FEM model and the experiments showed a good correspondence. It can be concluded that this novel biomimetic method can be further developed for detailed investigations of atherosclerotic lesions. Finally, we discuss various design strategies to optimize the output of the sensor using different simulated models to enhance target recognition.

  20. Extraction of a strongly focusing He+ beam from three-stage concave electrodes for alpha particle measurement system in ITER.

    PubMed

    Kobuchi, T; Sasao, M; Kisaki, M; Tsumori, K; Tanaka, N; Okamoto, A; Kitajima, S; Kaneko, O; Shinto, K; Wada, M

    2012-02-01

    A strongly focusing He(+) ion beam source equipped with concave multi-aperture electrodes was developed for production of He(-) through a charge exchange cell. The beam was extracted at a voltage less than 20 kV from 301 apertures distributed in an area of 100 mm ?, and focused at 750 mm distance. The beam current and the beam size of 2 A and 20 mm in diameter, respectively, were achieved with an arc power less than 10 kW. The optimum perveance was obtained at 0.02 A?kV(1.5) at the beam energy less than 20 keV which is suitable for the conversion to He(-) in an alkali vapor cell. PMID:22380277

  1. Measurement of low radioactivity background in a high voltage cable by high resolution inductively coupled plasma mass spectrometry

    SciTech Connect

    Vacri, M. L. di; Nisi, S.; Balata, M.

    2013-08-08

    The measurement of naturally occurring low level radioactivity background in a high voltage (HV) cable by high resolution inductively coupled plasma mass spectrometry (HR ICP MS) is presented in this work. The measurements were performed at the Chemistry Service of the Gran Sasso National Laboratory. The contributions to the radioactive background coming from the different components of the heterogeneous material were separated. Based on the mass fraction of the cable, the whole contamination was calculated. The HR ICP MS results were cross-checked by gamma ray spectroscopy analysis that was performed at the low background facility STELLA (Sub Terranean Low Level Assay) of the LNGS underground lab using HPGe detectors.

  2. High voltage DC power supply

    DOEpatents

    Droege, Thomas F. (Batavia, IL)

    1989-01-01

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively.

  3. High voltage DC power supply

    DOEpatents

    Droege, T.F.

    1989-12-19

    A high voltage DC power supply having a first series resistor at the output for limiting current in the event of a short-circuited output, a second series resistor for sensing the magnitude of output current, and a voltage divider circuit for providing a source of feedback voltage for use in voltage regulation is disclosed. The voltage divider circuit is coupled to the second series resistor so as to compensate the feedback voltage for a voltage drop across the first series resistor. The power supply also includes a pulse-width modulated control circuit, having dual clock signals, which is responsive to both the feedback voltage and a command voltage, and also includes voltage and current measuring circuits responsive to the feedback voltage and the voltage developed across the second series resistor respectively. 7 figs.

  4. Characteristics of distributed-type inorganic electroluminescence panels with comb-shaped electrodes

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shin-Ichi; Uraoka, Yukiharu; Taguchi, Nobuyoshi; Nonaka, Toshihiro

    2013-09-01

    We deposited comb electrodes with narrow gaps between the teeth on a glass substrate, thus realizing a high electric field intensity that cannot be achieved with conventional structures. Au electrodes are deposited to form a comb shape and then spin-coated with a phosphor layer obtained by mixing ZnS phosphor particles with resins in a certain ratio. An AC voltage was applied to the gaps between the teeth of the comb electrode to emit light, from which the luminance was measured for different electric field intensities. The luminance was not affected by the transmittance of the electrodes themselves when measured from the phosphor layer side. Therefore, it may be possible to produce a display that does not require transparent electrodes by using the phosphor layer side of a device with comb electrodes made of metals, such as Au, for the display.

  5. Electrical Rectification by a Monolayer of Hexadecylquinolinium Tricyanoquinodimethanide Measured between Macroscopic Gold Electrodes

    E-print Network

    Metzger, Robert M.

    Ved: March 22, 2001 Unimolecular rectification was detected between oxide-free Au electrodes for a Langmuir-Blodgett. Introduction Langmuir-Blodgett (LB) monolayers and multilayers of the ground-state zwitterionic donor

  6. Measurement and modelling of anomalous polarity pulses in a multi-electrode diamond detector

    E-print Network

    Forneris, J; Jaksic, M; Olivero, P; Picollo, F; Skukan, N; Verona, C; Verona-Rinati, G; Vittone, E

    2013-01-01

    In multi-electrode detectors, the motion of excess carriers generated by ionizing radiation induces charge pulses at the electrodes, whose intensities and polarities depend on the geometrical, electrostatic and carriers transport properties of the device. The resulting charge sharing effects may lead to bipolar currents, pulse height defects and anomalous polarity signals affecting the response of the device to ionizing radiation. This latter effect has recently attracted attention in commonly used detector materials, but different interpretations have been suggested, depending on the material, the geometry of the device and the nature of the ionizing radiation. In this letter, we report on the investigation in the formation of anomalous polarity pulses in a multi-electrode diamond detector with buried graphitic electrodes. In particular, we propose a purely electrostatic model based on the Shockley-Ramo-Gunn theory, providing a satisfactory description of anomalous pulses observed in charge collection effici...

  7. Near-electrode imager

    DOEpatents

    Rathke, Jerome W. (Lockport, IL); Klingler, Robert J. (Westmont, IL); Woelk, Klaus (Wachtberg, DE); Gerald, II, Rex E. (Brookfield, IL)

    2000-01-01

    An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager uses the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

  8. ESR Process Instabilities while Melting Pipe Electrodes

    SciTech Connect

    Melgaard, D.K.; Shelmidine, G.J.

    1999-01-06

    With the demonstration of the viability of using the electroslag remelting process for the decontamination of radionuclides, interest has increased in examining the unique aspects associated with melting steel pipe electrodes. These electrodes consist of several nested pipes, welded concentrically to atop plate. Since these electrodes can be half as dense as a solid electrode, they present unique challenges to the standard algorithms used in controlling the melting process. Naturally the electrode must be driven down at a dramatically increased speed. However, since the heat transfer is greatly influenced and enhanced with the increased area to volume ratio, considerable variation in the melting rate of the pipes has been found. Standard control methods can become unstable as a result of the variation at increased speeds, particularly at shallow immersion depths. The key to good control lies in the understanding of the melting process. Several experiments were conducted to observe the characteristics of the melting using two different control modes. By using a pressure transducer to monitor the pressure inside the pipes, the venting of the air trapped inside the electrode was observed. The measurements reveal that for a considerable amount of time. the pipes are not completely immersed in the slag, allowing the gas inside to escape without the formation of bubbles. This result has implications for the voltage swing as well as for the decontamination reactions.

  9. The Effect of Electrode Designs Based on the Anatomical Heart Location for the Non-Contact Heart Activity Measurement.

    PubMed

    Gi, Sun Ok; Lee, Young-Jae; Koo, Hye Ran; Lee, Seung Pyo; Lee, Kang-Hwi; Kim, Kyeng-Nam; Kang, Seung-Jin; Lee, Joo Hyeon; Lee, Jeong-Whan

    2015-12-01

    This research is an extension of a previous research [1] on the different effects of sensor location that is relatively suitable for heart rate sensing. This research aimed to elucidate the causes of wide variations in heart rate measurements from the same sensor position among subjects, as observed in previous research [1], and to enhance designs of the inductive textile electrode to overcome these variations. To achieve this, this study comprised two parts: In part 1, X-ray examinations were performed to determine the cause of the wide variations noted in the findings from previous research [1], and we found that at the same sensor position, the heart activity signal differed with slight differences in the positions of the heart of each subject owing to individual differences in the anatomical heart location. In part 2, three types of dual-loop-type textile electrodes were devised to overcome variations in heart location that were confirmed in part 1 of the study. The variations with three types of sensor designs were compared with that with a single-round type of electrode design, by using computer simulation and by performing a t-test on the data obtained from the experiments. We found that the oval-oval shaped, dual-loop-type textile electrode was more suitable than the single round type for determining morphological characteristics as well as for measuring appropriate heart activity signals. Based on these results, the oval-oval, dual-loop-type was a better inductive textile electrode that more effectively overcomes individual differences in heart location during heart activity sensing based on the magnetic-induced conductivity principle. PMID:26490149

  10. Electrodes for microfluidic applications

    DOEpatents

    Crocker, Robert W. (Fremont, CA); Harnett, Cindy K. (Livermore, CA); Rognlien, Judith L. (Livermore, CA)

    2006-08-22

    An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

  11. Design of an Ultra-Low Noise Analogue Front-End for Fast Voltage Pulses Measurement

    E-print Network

    AUTHOR|(SzGeCERN)712364; Arpaia, Pasquale; Cerqueira Bastos, Miguel; Martino, Michele

    2015-01-01

    A 15MS/s, 10 ppm repeatable acquisition system to characterize 3 ?s rise-time trapezoidal voltage pulses is proposed. The system is based mainly on a low-noise, 5MHz bandwidth analog front-end. In this paper, the requirements, the concept and physical design are illustrated. Simulation results aimed at assessing the circuit performance are presented. An experimental case study on the characterization of a pulsed power supply for the klystrons modulators of the Compact Linear Collider (CLIC) under study at CERN is reported. In particular, the experimental metrological characterization of the prototype in terms of bandwidth and noise is presented.

  12. A simple technique for measuring the fracture energy of lithiated thin-film silicon electrodes at various lithium concentrations

    NASA Astrophysics Data System (ADS)

    Choi, Yong Seok; Pharr, Matt; Oh, Kyu Hwan; Vlassak, Joost J.

    2015-10-01

    We have measured the fracture energy of lithiated silicon thin-film electrodes as a function of lithium concentration using a bending test. First, silicon thin-films on copper substrates were lithiated to various states of charge. Then, bending tests were performed by deforming the substrate to a pre-defined shape, producing a variation of the curvature along the length of the electrode. The bending tests allow determination of the critical strains at which cracks initiate in the lithiated silicon. Using the substrate curvature technique, we also measured the elastic moduli and the stresses that develop in the electrodes during electrochemical lithiation. From these measurements, the fracture energy was calculated as a function of lithium concentration using a finite element simulation of fracture of an elastic film on an elastic-plastic substrate. The fracture energy was determined to be ? = 12.0 ± 3.0 J m-2 for amorphous silicon and ? = 10.0 ± 3.6 J m-2 for Li3.28Si, with little variation in the fracture energy for intermediate Li concentrations. These results provide a guideline for the practical design of high-capacity lithium ion batteries to avoid fracture. The experimental technique described in this paper also provides a simple means of measuring the fracture energy of brittle thin-films.

  13. Boosting the Open Circuit Voltage and Fill Factor of QDSSCs Using Hierarchically Assembled ITO@Cu2S Nanowire Array Counter Electrodes.

    PubMed

    Jiang, Yan; Yu, Bin-Bin; Liu, Jie; Li, Zhi-Hua; Sun, Jian-Kun; Zhong, Xin-Hua; Hu, Jin-Song; Song, Wei-Guo; Wan, Li-Jun

    2015-05-13

    The key challenges in enhancing the power conversion efficiency (PCE) of a quantum dot-sensitized solar cell (QDSSC) are efficiently achieving charge separation at the photoanode and improving the charge transfer, which is limited by the interface between the electrolyte and the counter electrode (CE). Here, hierarchically assembled ITO@Cu2S nanowire arrays with conductive single-crystalline ITO cores and Cu2S nanocrystal shells were designed as efficient QDSSCs CEs. These arrays not only provided an efficient three-dimensional charge transport network but also allowed for the effective deposition of more Cu2S nanocrystals as active sites to catalyze the electrolyte reaction. This design considerably reduced the sheet and charge transfer resistance of the CE, thus decreasing the series resistance and increasing the shunt resistance of the QDSSC. As a result, QDSSCs with this CE exhibited an unprecedentedly high Voc of 0.688 V, a fill factor of 58.39%, and a PCE of 6.12%, which is 21.2% higher than that of the conventional brass/Cu2S CE. PMID:25929671

  14. Iridium oxide nanotube electrodes for sensitive and prolonged intracellular measurement of action potentials.

    PubMed

    Lin, Ziliang Carter; Xie, Chong; Osakada, Yasuko; Cui, Yi; Cui, Bianxiao

    2014-01-01

    Intracellular recording of action potentials is important to understand electrically-excitable cells. Recently, vertical nanoelectrodes have been developed to achieve highly sensitive, minimally invasive and large-scale intracellular recording. It has been demonstrated that the vertical geometry is crucial for the enhanced signal detection. Here we develop nanoelectrodes of a new geometry, namely nanotubes of iridium oxide. When cardiomyocytes are cultured upon those nanotubes, the cell membrane not only wraps around the vertical tubes but also protrudes deep into the hollow centre. We show that this nanotube geometry enhances cell-electrode coupling and results in larger signals than solid nanoelectrodes. The nanotube electrodes also afford much longer intracellular access and are minimally invasive, making it possible to achieve stable recording up to an hour in a single session and more than 8 days of consecutive daily recording. This study suggests that the nanoelectrode performance can be significantly improved by optimizing the electrode geometry. PMID:24487777

  15. Laser-based surface preparation of composite laminates leads to improved electrodes for electrical measurements

    NASA Astrophysics Data System (ADS)

    Almuhammadi, Khaled; Selvakumaran, Lakshmi; Alfano, Marco; Yang, Yang; Bera, Tushar Kanti; Lubineau, Gilles

    2015-12-01

    Electrical impedance tomography (EIT) is a low-cost, fast and effective structural health monitoring technique that can be used on carbon fiber reinforced polymers (CFRP). Electrodes are a key component of any EIT system and as such they should feature low resistivity as well as high robustness and reproducibility. Surface preparation is required prior to bonding of electrodes. Currently this task is mostly carried out by traditional sanding. However this is a time consuming procedure which can also induce damage to surface fibers and lead to spurious electrode properties. Here we propose an alternative processing technique based on the use of pulsed laser irradiation. The processing parameters that result in selective removal of the electrically insulating resin with minimum surface fiber damage are identified. A quantitative analysis of the electrical contact resistance is presented and the results are compared with those obtained using sanding.

  16. Thermo- and photoinduced voltages in Ag heterodimensional junctions

    SciTech Connect

    Xu Jia; Sun Jialin; Zhu Jialin

    2007-10-15

    Macroscopic-long Ag nanowires have been synthesized through an improved solid-state ionics method and characterized at different spatial scales. Using a bundle of as-fabricated Ag nanowires to connect with two bulk Ag electrodes, two Ag heterodimensional junctions are formed into an electrical circuit. Thermo- and photoinduced electromotive forces are observed and the corresponding voltages are measured in the circuit on the macroscale. For the photoinduced voltage, the fast dynamic response of the circuit, irradiated locally by 532 nm and 10.6 {mu}m lasers, is exhibited. The studied low-dimensional effects need to be taken into account in future applications of Ag nanowires.

  17. A bias voltage dependence of trapped hole annealing and its measurement technique

    SciTech Connect

    Kuboyama, S.; Goka, T.; Tamura, T. )

    1991-12-01

    This paper reports on a bias voltage dependence of the trapped hole annealing that was observed by using a unique irradiation technique with a MOS capacitor which exhibits almost no annealing of the trapped holes at negative bias condition. The result showed the change of time scale for the annealing behavior with the Boltzmann's factor as a function of surface potential of the substrate. This result suggests that the oxide of the MOS capacitor has trap level positioned above the Si conduction band edge. Additional annealing experiment at several temperatures supported the results and the position of the trap level was determined. The trap level confirmed may be one of commonly observed levels, although it is a special case that the MOS capacitor has only the trap level.

  18. Process for measuring degradation of sulfur hexafluoride in high voltage systems

    DOEpatents

    Sauers, Isidor (Knoxville, TN)

    1986-01-01

    This invention is a method of detecting the presence of toxic and corrosive by-products in high voltage systems produced by electrically induced degradation of SF.sub.6 insulating gas in the presence of certain impurities. It is an improvement over previous methods because it is extremely sensitive, detecting by-products present in parts per billion concentrations, and because the device employed is of a simple design and takes advantage of the by-products natural affinity for fluoride ions. The method employs an ion-molecule reaction cell in which negative ions of the by-products are produced by fluorine attachment. These ions are admitted to a negative ion mass spectrometer and identified by their spectra. This spectrometry technique is an improvement over conventional techniques because the negative ion peaks are strong and not obscured by a major ion spectra of the SF.sub.6 component as is the case in positive ion mass spectrometry.

  19. Process for measuring degradation of sulfur hexafluoride in high voltage systems

    DOEpatents

    Sauers, I.

    1985-04-23

    This invention is a method of detecting the presence of toxic and corrosive by-products in high voltage systems produced by electrically induced degradation of SF/sub 6/ insulating gas in the presence of certain impurities. It is an improvement over previous methods because it is extremely sensitive, detecting by-products present in parts per billion concentrations, and because the device employed is of a simple design and takes advantage of the by-products natural affinity for fluoride ions. The method employs an ion-molecule reaction cell in which negative ions of the by-products are produced by fluorine attachment. These ions are admitted to a negative ion mass spectrometer and identified by their spectra. This spectrometry technique is an improvement over conventional techniques because the negative ion peaks are strong and not obscured by a major ion spectra of the SF/sub 6/ component as is the case in positive ion mass spectrometry.

  20. Determining resistivity of a formation adjacent to a borehole having casing with an apparatus having all current conducting electrodes within the cased well

    DOEpatents

    Vail, III, William Banning (Bothell, WA)

    2001-01-01

    Methods of operation of different types of multiple electrode apparatus vertically disposed in a cased well to measure information useful to determine the resistivity of adjacent geological formations from within the cased well are described. The multiple electrode apparatus has a plurality of spaced apart voltage measurement electrodes that electrically engage a portion of the interior of the cased well. During measurements of information useful to determine formation resistivity, current is conducted between a first current conducting electrode in electrical contact with the interior of the cased well to a second current conducting electrode that is also in electrical contact with the interior of the cased well. The first and second current conducting electrodes are separated by a distance sufficient so that at least a portion of the current conducted between the first and second current conducting electrodes is conducted through the geological formation of interest.

  1. VOLTAMMETRIC MEMBRANE CHLORINE DIOXIDE ELECTRODE

    EPA Science Inventory

    A voltammetric membrane electrode system has been modified and applied to the in situ measurement of chlorine dioxide. The electrode system consisted of a gold cathode, a silver/silver chloride reference electrode, and a gold counter electrode. Different membrane materials were t...

  2. Disposable screen-printed bismuth electrode modified with multi-walled carbon nanotubes for electrochemical stripping measurements.

    PubMed

    Niu, Xiangheng; Zhao, Hongli; Lan, Minbo

    2011-01-01

    Integrating the advantages of screen printing technology with the encouraging electroanalytical characteristic of metallic bismuth, we developed an ultrasensitive and disposable screen-printed bismuth electrode (SPBE) modified with multi-walled carbon nanotubes (MWCNTs) for electrochemical stripping measurements. Metallic bismuth powders and MWCNTs were homogeneously mixed with graphite-carbon ink to mass-prepare screen-printed bismuth electrode doped with multi-walled carbon nanotubes (SPBE/MWCNT). The electroanalytical performance of the prepared SPBE/MWCNT was intensively evaluated by measuring trace Hg(II) with square-wave anodic stripping voltammetry (SWASV). The results indicated that the SPBE modified with 2 wt% MWCNTs could offer a more sensitive response to trace Hg(II) than the bare SPBE. The stripping current obtained at SPBE/MWCNT was linear with Hg(II) concentration in the range from 0.2 to 40 µg/L (R(2) = 0.9976), with a detection limit of 0.09 µg/L (S/N = 3) under 180 s accumulation. The proposed "mercury-free" electrode, with extremely simple preparation and ultrahigh sensitivity, holds wide application prospects in both environmental and industrial monitoring. PMID:22156253

  3. Automated targeting of cells to electrochemical electrodes using a surface chemistry approach for the measurement of quantal exocytosis.

    PubMed

    Barizuddin, Syed; Liu, Xin; Mathai, Joseph C; Hossain, Maruf; Gillis, Kevin D; Gangopadhyay, Shubhra

    2010-07-01

    Here we describe a method to fabricate a multi-channel high-throughput microchip device for measurement of quantal transmitter release from individual cells. Instead of bringing carbon-fiber electrodes to cells, the device uses a surface chemistry approach to bring cells to an array of electrochemical microelectrodes. The microelectrodes are small and "cytophilic" in order to promote adhesion of a single cell whereas all other areas of the chip are covered with a thin "cytophobic" film to block cell attachement and facilitate movement of cells to electrodes. This cytophobic film also insulates unused areas of the conductive film, thus the alignment of cell docking sites to working electrodes is automatic. Amperometric spikes resulting from single-granule fusion events were recorded on the device and had amplitudes and kinetics similar to those measured using carbon-fiber microelectrodes. Use of this device will increase the pace of basic neuroscience research and may also find applications in drug discovery or validation. PMID:21113333

  4. Carbon nanotube multi-electrode array chips for noninvasive real-time measurement of dopamine, action potentials, and postsynaptic potentials.

    PubMed

    Suzuki, Ikuro; Fukuda, Mao; Shirakawa, Keiichi; Jiko, Hideyasu; Gotoh, Masao

    2013-11-15

    Multi-electrode arrays (MEAs) can be used for noninvasive, real-time, and long-term recording of electrophysiological activity and changes in the extracellular chemical microenvironment. Neural network organization, neuronal excitability, synaptic and phenotypic plasticity, and drug responses may be monitored by MEAs, but it is still difficult to measure presynaptic activity, such as neurotransmitter release, from the presynaptic bouton. In this study, we describe the development of planar carbon nanotube (CNT)-MEA chips that can measure both the release of the neurotransmitter dopamine as well as electrophysiological responses such as field postsynaptic potentials (fPSPs) and action potentials (APs). These CNT-MEA chips were fabricated by electroplating the indium-tin oxide (ITO) microelectrode surfaces. The CNT-plated ITO electrode exhibited electrochemical response, having much higher current density compared with the bare ITO electrode. Chronoamperometric measurements using these CNT-MEA chips detected dopamine at nanomolar concentrations. By placing mouse striatal brain slices on the CNT-MEA chip, we successfully measured synaptic dopamine release from spontaneous firings with a high S/N ratio of 62. Furthermore, APs and fPSPs were measured from cultured hippocampal neurons and slices with high temporal resolution and a 100-fold greater S/N ratio. Our CNT-MEA chips made it possible to measure neurotransmitter dopamine (presynaptic activities), postsynaptic potentials, and action potentials, which have a central role in information processing in the neuronal network. CNT-MEA chips could prove useful for in vitro studies of stem cell differentiation, drug screening and toxicity, synaptic plasticity, and pathogenic processes involved in epilepsy, stroke, and neurodegenerative diseases. PMID:23774164

  5. [A method for impedance measurements based on EEG acquisition system].

    PubMed

    Ye, Jilun; Wei, Lanlan; Wang, Fan; Song, Yantao; Zhang, Xu

    2014-07-01

    In the bioelectric measurement, the electrode impedance detection is an important index to the signal quality evaluation and sensor electrode contact condition. In this paper, a method of accurately measuring the electrode impedance based on EEG measurement system was put forward, the method is based on the constant current source excitation signals which are added to the human body, by monitoring the human voltage to measure the electrode impedance. And different reference resistor calibration calculation in different sections was used to reduce the effect of constant current source on the precision of measurement results to improve the measurement accuracy. PMID:25330599

  6. Application of HFCT and UHF Sensors in On-Line Partial Discharge Measurements for Insulation Diagnosis of High Voltage Equipment

    PubMed Central

    Álvarez, Fernando; Garnacho, Fernando; Ortego, Javier; Sánchez-Urán, Miguel Ángel

    2015-01-01

    Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment. PMID:25815452

  7. Modeling gating charge and voltage changes in response to charge separation in membrane proteins

    PubMed Central

    Kim, Ilsoo; Chakrabarty, Suman; Brzezinski, Peter; Warshel, Arieh

    2014-01-01

    Measurements of voltage changes in response to charge separation within membrane proteins can offer fundamental information on mechanisms of charge transport and displacement processes. A recent example is provided by studies of cytochrome c oxidase. However, the interpretation of the observed voltage changes in terms of the number of charge equivalents and transfer distances is far from being trivial or unique. Using continuum approaches to describe the voltage generation may involve significant uncertainties and reliable microscopic simulations are not yet available. Here, we attempt to solve this problem by using a coarse-grained model of membrane proteins, which includes an explicit description of the membrane, the electrolytes, and the electrodes. The model evaluates the gating charges and the electrode potentials (c.f. measured voltage) upon charge transfer within the protein. The accuracy of the model is evaluated by a comparison of measured voltage changes associated with electron and proton transfer in bacterial photosynthetic reaction centers to those calculated using our coarse-grained model. The calculations reproduce the experimental observations and thus indicate that the method is of general use. Interestingly, it is found that charge-separation processes with different spatial directions (but the same distance perpendicular to the membrane) can give similar observed voltage changes, which indicates that caution should be exercised when using simplified interpretation of the relationship between charge displacement and voltage changes. PMID:25049404

  8. Low Impedance Carbon Adhesive Electrodes with Long Shelf Life.

    PubMed

    Posada-Quintero, Hugo F; Reyes, Bersaín A; Burnham, Ken; Pennace, John; Chon, Ki H

    2015-10-01

    A novel electrocardiogram (ECG) electrode film is developed by mixing carbon black powder and a quaternary salt with a visco-elastic polymeric adhesive. Unlike traditional wet gel-based electrodes, carbon/salt/adhesive (CSA) electrodes should theoretically have an infinite shelf life as they do not dehydrate even after a prolonged period of storage. The CSA electrodes are electrically activated for use through the process of electrophoresis. Specifically, the activation procedure involves sending a high voltage and current through the electrode, which results in significant reduction of impedance so that high fidelity ECG signals can be obtained. Using the activation procedure, the ideal concentration of carbon black powder in the mixture with the adhesive was examined. It was determined that the optimum concentration of carbon black which minimized post-activation impedance was 10%. Once the optimal carbon black powder concentration was determined, extensive signal analysis was performed to compare the performance of the CSA electrodes to the standard silver-silver chloride (Ag/AgCl) electrodes. As a part of data analysis, electrode-skin contact impedance of the CSA was measured and compared to the standard Ag/AgCl electrodes; we found consistently lower impedance for CSA electrodes. For quantitative data analysis, we simultaneously collected ECG data with CSA and Ag/AgCl electrodes from 17 healthy subjects. Heart rate variability (HRV) indices and ECG morphological waveforms were calculated to compare CSA and Ag/AgCl electrodes. Non-significant differences for most of the HRV indices between CSA and Ag/AgCl electrodes were found. Of the morphological waveform metrics consisting of R-wave peak amplitude, ST-segment elevation and QT interval, only the first index was found to be significantly different between the two media. The response of CSA electrodes to motion artifacts was also tested, and we found in general no difference in the quality of the ECG signal between the two media. Hence, given that CSA electrodes are expected to have a very long shelf-life, with potentially less cost associated with their fabrication, and have ECG signal dynamics nearly identical to those of Ag/AgCl, the new electrodes provide an attractive alternative for ECG measurements. PMID:25691400

  9. A method for measuring high resistances with negligible leakage effect using one voltage source and one voltmeter

    NASA Astrophysics Data System (ADS)

    Yu, Kwang Min; Kim, Wan Seop; Lee, Sang Hwa; Han, Kwon Soo; Kang, Jeon Hong

    2014-07-01

    We present a method for measuring high resistances using one voltage source and one voltmeter. With this method, there exist two techniques. One is to measure a high resistance with a much lower resistance and the other is to cancel the leakage effect effectively using two nominally equal resistances without an auxiliary guarding apparatus. To demonstrate the method's validity, a 1 G? resistance was measured using the two techniques replacing a dummy 1 G? resistance as a leakage resistance; the measurement results agree well with the theoretical results within the measurement uncertainty of 3 × 10-6 (k = 2) level. We used the method to determine 10 M?, 1 G? and 1 T? resistances with an active-guard type and a T-type. The best expanded uncertainties at k = 2 from the results were estimated as 0.3 × 10-6, 0.8 × 10-6 and 20 × 10-6, respectively. We also show that while the expanded uncertainty of 70 × 10-6 is obtained using an 81/2 digit digital multimeter, it is improved to 20 × 10-6 using an electrometer with high-input resistance, low bias current and high resolution when the second technique is used to measure high resistances.

  10. Changes in biphasic electrode impedance with protein adsorption and cell growth

    PubMed Central

    Newbold, Carrie; Richardson, Rachael; Millard, Rodney; Huang, Christie; Milojevic, Dusan; Shepherd, Robert; Cowan, Robert

    2012-01-01

    This study was undertaken to assess the contribution of protein adsorption and cell growth to increases in electrode impedance that occur immediately following implantation of cochlear implant electrodes and other neural stimulation devices. An in vitro model of the electrode-tissue interface was used. Radiolabelled albumin in phosphate buffered saline was added to planar gold electrodes and electrode impedance measured using a charge-balanced biphasic current pulse. The polarisation impedance component increased with protein adsorption, while no change to access resistance was observed. The maximum level of protein adsorbed was measured at 0.5 ?g/cm2, indicating a tightly packed monolayer of albumin molecules on the gold electrode and resin substrate. Three cell types were grown over the electrodes, macrophage cell line J774, dissociated fibroblasts and epithelial cell line MDCK, all of which created a significant increase in electrode impedance. As cell cover over electrodes increased, there was a corresponding increase in the initial rise in voltage, suggesting cell cover mainly contributes to the access resistance of the electrodes. Only a small increase in the polarisation component of impedance was seen with cell cover. PMID:20841637

  11. Development of PDMS-based flexible dry type SEMG electrodes by micromachining technologies

    NASA Astrophysics Data System (ADS)

    Jung, Jung Mo; Cha, Doo Yeol; Kim, Deok Su; Yang, Hee Jun; Choi, Kyo Sang; Choi, Jong Myoung; Chang, Sung Pil

    2014-09-01

    The authors developed PDMS (polydimethylsiloxane)-based dry type surface electromyography (SEMG) electrodes for myoelectric prosthetic hands. The SEMG electrodes were strongly recommended to be fabricated on a flexible substrate to be compatible with the surface of skin. In this study, the authors designed a bar-shaped dry-type flexible SEMG electrodes comprised of two input electrodes and a reference electrode on a flexible PDMS substrate to measure EMG signals. The space distance between each electrode with a size of 10 mm × 2 mm was chosen to 18 mm to get optimal result according to the simulation result with taking into consideration the conduction velocity and the median frequency of EMG signals. Raw EMG signals were measured from Brachioradialis, Biceps brachii, deltoideus, and pectoralis major muscles, to drive the application of the myoelectric hand prosthesis. Measured raw EMG signals were transformed to root mean square (RMS) EMG signals using Acqknowledge4.2. The experimental peak voltage values of RMS EMG signals from Brachioradialis, Biceps brachii, deltoideus, and pectoralis major muscles were 2.96 V, 4.45 V, 1.74 V, and 2.62 V, respectively. Values from the dry type flexible SEMG electrodes showed higher peak values than a commercially available wet type Ag-AgCl electrode. The study shows that the PDMS-based flexible electrode devised for measuring myoelectric signals from the surface of skin is more useful for prosthetic hands because of its greater sensitivity and flexibility.

  12. Tunneling spectroscopy of clean and adsorbate-covered gold surfaces in humid air, measured with fast bias voltage ramps

    NASA Astrophysics Data System (ADS)

    Rösch, Raphael; Schuster, Rolf

    2015-01-01

    The noise level of tunneling spectroscopic data can be significantly reduced by averaging the tunneling current over a large number of short bias voltage ramps, instead of recording over a single slow ramp. This effect is demonstrated for tunneling spectra of Au(111) by averaging over 200 consecutive bias voltage ramps, each 500 ?s long. We attribute the improvement of the data quality to the frequency dependence of the current noise spectral density. Due to mechanical vibrations and tip instabilities the noise density is usually much higher for low frequencies ca. < 1 kHz than for the high frequencies relevant for measuring with fast bias ramps. The high data quality allowed for the routine detection of the Au(111) surface state and the investigation of the influence of steps in humid air, i.e., with a water-covered tunneling gap. For a CN covered Au surface in the presence of water we unexpectedly found additional electronic density of states at positive energies, around 0.6 eV, i.e., for unoccupied states. STS spectra of a (?{ 3} ×?{ 3}) R 30 ° Cu-UPD layer, formed by adsorbed sulfate and Cu species, indicate tunneling via the sulfate electronic density of states.

  13. Quantitative measurement of voltage dependence of spin-transfer torque in

    E-print Network

    Loss, Daniel

    -torque- induced magnetization switching and microwave emission (107 A cm-2 ), accurately measuring the strength the Methods section for preparation details). Resistance­magnetic-field (R­H) curves measured at a small biasO-based magnetic tunnel junctions HITOSHI KUBOTA1 *, AKIO FUKUSHIMA1 , KAY YAKUSHIJI1 , TARO NAGAHAMA1 , SHINJI

  14. Flexible gold electrode array for multiplexed immunoelectrochemical measurement of three protein biomarkers for prostate cancer.

    PubMed

    Liu, Jing; Lu, Cai-Yu; Zhou, Hong; Xu, Jing-Juan; Chen, Hong-Yuan

    2014-11-26

    In this work, we report a simple and novel electrochemical multiplexed immunosensor on a flexible polydimethylsiloxane (PDMS) slice deposited with 8 × 8 nano-Au film electrodes for simultaneous detection of prostate specific antigen (PSA), prostate specific membrane antigen (PSMA), and interleukin-6 (IL-6). Primary antibodies linked with magnetic beads (Ab1-MBs) were modified on the nano-Au film electrodes via magnetic force. In the presence of corresponding antigen, horse radish peroxidase-secondary antibody-conjugated gold nanorods (HRP-Ab2-gold NRs) were brought into the surface of electrodes, generating obvious electrochemical signals of H2O2 reduction reactions. Based on this, the designed immunosensor provide good performance in sensitivity and specificity during the detection of above three biomarkers for prostate cancer. The electrochemical multiplexed immunosensor was verified for selective and accurate detection of complex samples in human serum. Data suggested that the reported multiplexed immunosensing strategy holds great promise for applications in clinical assay and diseases diagnosis. PMID:25333408

  15. Development of a versatile rotating ring-disc electrode for in situ pH measurements.

    PubMed

    Zimer, Alexsandro Mendes; Medina da Silva, Marina; Machado, Eduardo G; Varela, Hamilton; Mascaro, Lucia Helena; Pereira, Ernesto Chaves

    2015-10-15

    There are some electrocatalytic reactions in which the key parameter explaining their behavior is a local change in pH. Therefore, it is of utter importance to develop an electrode that could quantify this parameter in situ, but also be customizable to be used in different systems. The purpose of this work is to build a versatile rotating ring/disc electrode (RRDE) with IrOx deposited on a glass tube as a ring and any kind of material as disc. As the IrOx is sensitive to pH variation, the reactions promoted on the disc can trigger proportional pH shifts on the ring. In such assembly, the IrOx ring presents a fast response time even during the pH transients due to the small thickness of the ring (approximately 10 ?m), which enables the detection of interfacial pH changes. The ring electrode was tested toward the interfacial pH shift observed during the electrolytic reduction of water on the disc and also characterized by acid-base titration to determine the response time. As the main conclusions, fast response and durable RRDE were obtained, and this assembly could be used to revisit many electrocatalytic reactions in order to test the importance of local pH on the process. PMID:26515001

  16. Effect of Electrode Shape on Impedance of Single HeLa Cell: A COMSOL Simulation.

    PubMed

    Wang, Min-Haw; Chang, Wen-Hao

    2015-01-01

    In disease prophylaxis, single cell inspection provides more detailed data compared to conventional examinations. At the individual cell level, the electrical properties of the cell are helpful for understanding the effects of cellular behavior. The electric field distribution affects the results of single cell impedance measurements whereas the electrode geometry affects the electric field distributions. Therefore, this study obtained numerical solutions by using the COMSOL multiphysics package to perform FEM simulations of the effects of electrode geometry on microfluidic devices. An equivalent circuit model incorporating the PBS solution, a pair of electrodes, and a cell is used to obtain the impedance of a single HeLa cell. Simulations indicated that the circle and parallel electrodes provide higher electric field strength compared to cross and standard electrodes at the same operating voltage. Additionally, increasing the operating voltage reduces the impedance magnitude of a single HeLa cell in all electrode shapes. Decreasing impedance magnitude of the single HeLa cell increases measurement sensitivity, but higher operational voltage will damage single HeLa cell. PMID:25961043

  17. Effect of Electrode Shape on Impedance of Single HeLa Cell: A COMSOL Simulation

    PubMed Central

    Chang, Wen-Hao

    2015-01-01

    In disease prophylaxis, single cell inspection provides more detailed data compared to conventional examinations. At the individual cell level, the electrical properties of the cell are helpful for understanding the effects of cellular behavior. The electric field distribution affects the results of single cell impedance measurements whereas the electrode geometry affects the electric field distributions. Therefore, this study obtained numerical solutions by using the COMSOL multiphysics package to perform FEM simulations of the effects of electrode geometry on microfluidic devices. An equivalent circuit model incorporating the PBS solution, a pair of electrodes, and a cell is used to obtain the impedance of a single HeLa cell. Simulations indicated that the circle and parallel electrodes provide higher electric field strength compared to cross and standard electrodes at the same operating voltage. Additionally, increasing the operating voltage reduces the impedance magnitude of a single HeLa cell in all electrode shapes. Decreasing impedance magnitude of the single HeLa cell increases measurement sensitivity, but higher operational voltage will damage single HeLa cell. PMID:25961043

  18. Aquifer and Vadose Zone Pollution Determined From Geoelectrical Measurements With Multi- Electrode Wells and Surface Multi-Profiling

    NASA Astrophysics Data System (ADS)

    de Lima, O. A.; Pereira, P. D.

    2007-05-01

    During the last three years we are developing hydrobiogeological researches to quantitatively describe the underground contamination of a 4.0 km2 area, including two landfill deposits and a tannery industry of Alagoinhas city, Bahia state, Brazil. We used electrical geophysics, geological, geochemical and biological analysis to gain a general understanding of the complex interactions between organic and inorganic pollutants and their environmental impacts. A geological reconnaissance work and a geoelectrical survey using vertical electrical soundings were made around the area to detect and to delineate the extent of the underground contamination plume. The results pointed out the presence of a strong conductive anomaly within the aquifer resulting from invasive fluids both from the landfills and from the surface disposal lagoons from the tannery. Water samples collected at available wells and along the Sauipe river, have shown drastic changes in the total dissolved solids, total chromium, inorganic macro-components, biochemical oxygen demand, chemical oxygen demand, nutrients and bacterial content. As a complimentary work, apparent resistivity and chargeability data were measured as a function of depth along three new multi-electrode wells, and as a function of electrode spacing along five double semi-Schlumberger subsurface profiles. A multi-electrode well is a special monitoring well where we externally install copper electrodes as thin metallic rings spaced by 0.50 m, along its entire filter and casing length. Such electrodes are connected through insulated cables to the ground surface and may be combined into different arrays. Two-side semi-Schlumberger soundings expanded up to 200 m AB/2 spacing and with centers spaced by 50 m along special transverse centered at the plume were inverted using 1D and 2D models. Both techniques were used to detail the groundwater contamination around the Alagoinhas landfills. The electrical measurements performed at the earth surface and within wells, were used both to characterize the plume and to estimate changes in water saturation and water chemistry bellow the water table and throughout the upper vadose section of the Marizal- São Sebastião aquifer system. Well data were acquired during three different campaigns of 2004-2006 years, covering a complete seasonal cycle. The results are quantitativelyinterpreted using the volume conductivity approach described by Lima et al. (2005) extended for condiction of partial water saturation.

  19. Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line.

    PubMed

    Zhou, Qiang; He, Wei; Xiao, Dongping; Li, Songnong; Zhou, Kongjun

    2015-01-01

    A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid. PMID:26729119

  20. An approach to the diagnosis of metabolic syndrome by the multi-electrode impedance method

    NASA Astrophysics Data System (ADS)

    Furuya, N.; Sakamoto, K.; Kanai, H.

    2010-04-01

    It is well known that metabolic syndrome can induce myocardial infarction and cerebral infarction. So, it is very important to measure the visceral fat volume. In the electric impedance method, information in the vicinity of the electrodes is strongly reflected. Therefore, we propose a new multi-electrode arrangement method based on the impedance sensitivity theorem to measure the visceral fat volume. This electrode arrangement is designed to enable high impedance sensitivity in the visceral and subcutaneous fat regions. Currents are simultaneously applied to several current electrodes on the body surface, and one voltage electrode pair is arranged on the body surface near the organ of interest to obtain the visceral fat information and another voltage electrode pair is arranged on the body surface near the current electrodes to obtain the subcutaneous fat information. A simulation study indicates that by weighting the impedance sensitivity distribution, as in our method, a high-sensitivity region in the visceral and the subcutaneous fat regions can be formed. In addition, it was confirmed that the visceral fat volume can be estimated by the measured impedance data.

  1. Constant voltage electro-slag remelting control

    DOEpatents

    Schlienger, M.E.

    1996-10-22

    A system for controlling electrode gap in an electro-slag remelt furnace has a constant regulated voltage and an electrode which is fed into the slag pool at a constant rate. The impedance of the circuit through the slag pool is directly proportional to the gap distance. Because of the constant voltage, the system current changes are inversely proportional to changes in gap. This negative feedback causes the gap to remain stable. 1 fig.

  2. Alkali metal ion battery with bimetallic electrode

    SciTech Connect

    Boysen, Dane A; Bradwell, David J; Jiang, Kai; Kim, Hojong; Ortiz, Luis A; Sadoway, Donald R; Tomaszowska, Alina A; Wei, Weifeng; Wang, Kangli

    2015-04-07

    Electrochemical cells having molten electrodes having an alkali metal provide receipt and delivery of power by transporting atoms of the alkali metal between electrode environments of disparate chemical potentials through an electrochemical pathway comprising a salt of the alkali metal. The chemical potential of the alkali metal is decreased when combined with one or more non-alkali metals, thus producing a voltage between an electrode comprising the molten the alkali metal and the electrode comprising the combined alkali/non-alkali metals.

  3. Transport characteristics of n-ZnO/p-Si heterojunction as determined from temperature dependent current-voltage measurements

    NASA Astrophysics Data System (ADS)

    Djiokap, S. R. Tankio; Urgessa, Z. N.; Mbulanga, C. M.; Venter, A.; Botha, J. R.

    2016-01-01

    Zinc oxide (ZnO) nanorods have been synthesized by a two-step chemical bath deposition process on silicon substrates having different dopant densities and orientations. Scanning electron microscopy and X-ray diffraction analysis reveal that the orientation of the Si substrate does not affect the orientation, distribution or crystallinity of the nanostructures. The electrical properties of the ZnO/Si heterojunction are also investigated by current-voltage (I-V) measurements. The ideality factor is found to be 2.6 at 295 K, indicating that complex current transport mechanisms are at play. Temperature dependent I-V characteristics have been used to determine the dominant transport mechanism. The experimental results suggest that in the low bias region the current is dominated by a trap assisted multi-step tunneling process.

  4. Effect of test conditions and sample configuration on the AMTEC electrode/electrolyte characteristics measurements in the Sodium Exposure Test Cell experiment 

    E-print Network

    Azimov, Ulughbek Bakhadirovich

    2001-01-01

    %) on the measurements at typical AMTEC operating temperatures. Electrochemical Impedance Spectroscopy (EIS) and controlled potential current-voltage curves (iV curves) techniques were used to determine these characteristics....

  5. Fabrication of Functionalized Carbon Nanotube Buckypaper Electrodes for Application in Glucose Biosensors

    PubMed Central

    Papa, Henry; Gaillard, Melissa; Gonzalez, Leon; Chatterjee, Jhunu

    2014-01-01

    A highly sensitive glucose detection method was developed using functionalized carbon nanotube buckypaper as a free standing electrode in an electrochemical biosensor. Glucose oxidase was immobilized onto various buckypaper samples in order to oxidize glucose resulting in a measureable current/voltage signal output of the biosensor. Cyclic voltammetry (CV) and amperometry were utilized to determine the sensitivity of these buckypaper electrodes. Sensors of three different types of buckypaper were prepared and compared. These modified buckypaper electrode-based sensors showed much higher sensitivity to glucose compared to other electrochemical glucose sensors. PMID:25587433

  6. Drop short control of electrode gap

    DOEpatents

    Fisher, Robert W. (Albuquerque, NM); Maroone, James P. (Albuquerque, NM); Tipping, Donald W. (Albuquerque, NM); Zanner, Frank J. (Sandia Park, NM)

    1986-01-01

    During vacuum consumable arc remelting the electrode gap between a consumable electrode and a pool of molten metal is difficult to control. The present invention monitors drop shorts by detecting a decrease in the voltage between the consumable electrode and molten pool. The drop shorts and their associated voltage reductions occur as repetitive pulses which are closely correlated to the electrode gap. Thus, the method and apparatus of the present invention controls electrode gap based upon drop shorts detected from the monitored anode-cathode voltage. The number of drop shorts are accumulated, and each time the number of drop shorts reach a predetermined number, the average period between drop shorts is calculated from this predetermined number and the time in which this number is accumulated. This average drop short period is used in a drop short period electrode gap model which determines the actual electrode gap from the drop short. The actual electrode gap is then compared with a desired electrode gap which is selected to produce optimum operating conditions and the velocity of the consumable error is varied based upon the gap error. The consumable electrode is driven according to any prior art system at this velocity. In the preferred embodiment, a microprocessor system is utilized to perform the necessary calculations and further to monitor the duration of each drop short. If any drop short exceeds a preset duration period, the consumable electrode is rapidly retracted a predetermined distance to prevent bonding of the consumable electrode to the molten remelt.

  7. Output trends, characteristics, and measurements of three mega-voltage radiotherapy linear accelerators

    PubMed Central

    Hossain, Murshed

    2015-01-01

    The purpose of this study is to characterize and understand the long term behavior of the output from megavoltage radiotherapy linear accelerators. Output trends of nine beams from three linear accelerators over a period of more than three years are reported and analyzed. Output taken during daily warm-up forms the basis of this study. The output is measured using devices having ion-chambers. These are not calibrated by accredited dosimetry laboratory but are baseline compared against monthly output which are measured using calibrated ion-chambers. We consider the output from the daily check devices as it is and sometimes normalized them by the actual output measured during the monthly calibration of the Linacs. The data shows noisy quasi-periodic behavior. The output variation if normalized by monthly measured “real’ output, is bounded between ±3%. Beams of different energies from the same Linac are correlated with a correlation coefficient as high as 0.97 for one particular Linac and as low as 0.44 for another. These maximum and minimum correlations drop to 0.78 and 0.25 when daily output is normalized by the monthly measurements. These results suggest that the origin of these correlations are both the Linacs and the daily output check devices. Beams from different Linacs, independent of their energies, have lower correlation coefficient with a maximum of about 0.50 and a minimum of almost zero. The maximum correlation drops to almost zero if the output is normalized by the monthly measured output. Some scatter plots of pairs of beam-output from the same Linac show band-like structures. These structures are blurred when the output is normalized by the monthly calibrated output. Fourier decomposition of the quasi periodic output is consistent with a 1/f power law. The output variation appears to come from a distorted normal distribution with a mean of slightly greater than unity. The quasi-periodic behavior is manifested in the seasonally averaged output showing annual variability with negative variations in the winter and positive in the summer. This trend is weakened when the daily output is normalized by the monthly calibrated output indicating that the variation of the periodic component may be intrinsic to both the Linacs and the daily measurement devices. Actual Linac output was measured monthly. It is needed to be adjusted once every 3-6 months for our tolerance and action levels. If these adjustments are artificially removed then there is an increase in output of about 2-4% per year. PMID:25207404

  8. Filter-fluorescer measurement of low-voltage simulator x-ray energy spectra

    SciTech Connect

    Baldwin, G.T.; Craven, R.E.

    1986-01-01

    X-ray energy spectra of the Maxwell Laboratories MBS and Physics International Pulserad 737 were measured using an eight-channel filter-fluorescer array. The PHOSCAT computer code was used to calculate channel response functions, and the UFO code to unfold spectrum.

  9. Electrochemical thermodynamic measurement system

    DOEpatents

    Reynier, Yvan (Meylan, FR); Yazami, Rachid (Los Angeles, CA); Fultz, Brent T. (Pasadena, CA)

    2009-09-29

    The present invention provides systems and methods for accurately characterizing thermodynamic and materials properties of electrodes and electrochemical energy storage and conversion systems. Systems and methods of the present invention are configured for simultaneously collecting a suite of measurements characterizing a plurality of interconnected electrochemical and thermodynamic parameters relating to the electrode reaction state of advancement, voltage and temperature. Enhanced sensitivity provided by the present methods and systems combined with measurement conditions that reflect thermodynamically stabilized electrode conditions allow very accurate measurement of thermodynamic parameters, including state functions such as the Gibbs free energy, enthalpy and entropy of electrode/electrochemical cell reactions, that enable prediction of important performance attributes of electrode materials and electrochemical systems, such as the energy, power density, current rate and the cycle life of an electrochemical cell.

  10. Objective Measures of Electrode Discrimination with Electrically-Evoked Auditory Change Complex and Speech Perception Abilities in Children with Auditory Neuropathy Spectrum Disorder

    PubMed Central

    He, Shuman; Grose, John H.; Teagle, Holly F.B.; Buchman, Craig A.

    2014-01-01

    Objective: This study aimed to 1) determine the sensitivity of the electrically evoked auditory change complex (eACC) to changes in stimulating electrode position; and 2) investigate the association between results of eACC measures and behavioral electrode discrimination and their association with speech-perception performance in pediatric cochlear implant (CI) users who have auditory neuropathy spectrum disorder (ANSD). Design: Fifteen children with ANSD ranging in age between 5.4 and 18.6 yrs participated in this study. All subjects used Cochlear Nucleus devices. For each subject, open-set speech perception ability was assessed using the Phonetically Balanced Kindergarten (PBK) word lists presented at 60 dB SPL using monitored live voice in a sound booth. Behavioral and objective measures of electrode discrimination were made in a non-clinical test environment. The stimuli used to elicit these measures were 800-ms biphasic pulse trains delivered by a direct interface to the cochlear implant. Data were collected from two basic stimulation conditions. In the standard condition, the entire pulse train was delivered to a mid-array electrode (electrode 11 or 12) at the maximum comfortable level (C level). In the change condition, the stimulus was split into two 400-ms pulse train segments presented sequentially on two different electrodes. The stimulation level of the second 400-ms pulse train was loudness balanced to the C level of the mid-array electrode used in the standard condition. The separation between the pair of stimulating electrodes was systematically varied. For behavioral electrode discrimination measures, each subject was required to determine whether they heard one or two sounds for stimuli presented in different stimulation conditions. For the eACC measures, two replicates of 100 artifact-free sweeps were recorded for each stimulation condition. Results: The eACC in response to changes in stimulating electrode position was recorded from all subjects with ANSD using direct electrical stimulation. Electrode discrimination thresholds determined with the eACC and behavioral measures were consistent. Children with ANSD using cochlear implants who showed poorer speech performance also required larger separations between the stimulating electrode pair to reliably elicit the eACC than subjects with better speech-perception performance. There was a robust correlation between electrode discrimination capacities and speech-perception performances in subjects tested in this study. The effect of electrode separation on eACC amplitudes was not monotonic. Conclusions: These results demonstrate the feasibility of using the eACC to evaluate electrode discrimination capacities in children with ANSD. These results suggest that the eACC elicited by changes in stimulating electrode position holds great promise as an objective tool for evaluating spectral pattern detection in this population, which may be predictive of their potential speech-perception performance. PMID:24231629

  11. Note: Effective measurement of retained Ic in evaluating electromechanical properties of high temperature superconductor tapes by the voltage tap clipping technique

    NASA Astrophysics Data System (ADS)

    Dedicatoria, Marlon J.; Bautista, Zhierwinjay; Shin, Hyung-Seop; Sim, Kideok

    2015-08-01

    In this note, the effectiveness of voltage tap clipping technique was assessed in evaluating the electromechanical properties of high temperature superconductor (HTS) tapes in the aspect of practical device applications. In the four-probe transport Ic measurement, instead of directly soldering the voltage lead wires onto the HTS samples, they were tapped to the sample by either just clipping or soldering them to the clips. This technique facilitated the simultaneous and repeated retained Ic measurement test for multiple samples. Finally, the critical double bending diameter of HTS tapes and the electrical properties of jointed and striated coated conductor tapes could be easily determined.

  12. Near-uv photon efficiency in a TiO2 electrode - Application to hydrogen production from solar energy

    NASA Technical Reports Server (NTRS)

    Desplat, J.-L.

    1976-01-01

    An n-type (001) TiO2 electrode irradiated at 365 nm was tested under anodic polarization. A saturation current independent of pH and proportional to light intensity has been observed. Accurate measurements of the incident power lead to a 60 per cent photon efficiency. A photoelectrochemical cell built with such an electrode, operated under solar irradiation without concentration, produced an electrolysis current of 0.7 mA/sq cm without applied voltage.

  13. Electrochemical properties of titanium nitride nerve stimulation electrodes: an in vitro and in vivo study

    PubMed Central

    Meijs, Suzan; Fjorback, Morten; Jensen, Carina; Sørensen, Søren; Rechendorff, Kristian; Rijkhoff, Nico J. M.

    2015-01-01

    The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements. Five electrodes were kept in Ringer's solution at 37.5°C, of which four were used for electrical stimulation and electrochemical measurements. The voltage transients measured in vivo were 13 times greater than in vitro at implantation and they continued to increase with time. The electrochemical properties in vivo and the tissue resistance (Rtissue) followed a similar trend with time. There was no consistent significant difference between the electrochemical properties of the in vivo and in vitro electrodes after the implanted period. The differences between the in vivo and in vitro electrodes during the implanted period show that the evaluation of electrochemical performance of implantable stimulation electrodes cannot be substituted with in vitro measurements. After the implanted period, however, the performance of the in vivo and in vitro electrodes in saline was similar. In addition, the changes observed over time during the post-implantation period regarding the electrochemical properties of the in vivo electrodes and Rtissue were similar, which indicates that these changes are due to the foreign body response to implantation. PMID:26300717

  14. Measurement of Fast Voltage Transients in High-Performance Nb3Sn Magnets

    SciTech Connect

    Lietzke, A. F.; Sabbi., G. L.; Ferracin, P.; Caspi, S.; Zimmerman, S.; Joseph, J.; Doering, D.; Lizarazo, J.

    2008-06-01

    The Superconducting Magnet group at Lawrence Berkeley National Laboratory has been developing Nb{sub 3}Sn high-field accelerator magnet technology for the last fifteen years. In order to support the magnet R&D effort, we are developing a diagnostic system that can help identify the causes of performance limiting quenches by recording small flux-changes within the magnet prior to quench-onset. These analysis techniques were applied to the test results from recent Nb{sub 3}Sn magnets. This paper will examine various types of events and their distinguishing characteristics. The present measurement techniques are discussed along with the design of a new data acquisition system that will substantially improve the quality of the recorded signals.

  15. Redox Cycling Without Reference Electrode

    PubMed Central

    Sarkar, Sahana; Mathwig, Klaus; Kang, Shuo; Nieuwenhuis, Ab. F.; Lemay, Serge G.

    2015-01-01

    The reference electrode is a key component in electrochemical measurements, yet it remains a challenge to implement a reliable reference electrode in miniaturized electrochemical sensors. Here we explore experimentally and theoretically an alternative approach based on redox cycling which eliminates the reference electrode altogether. We show that shifts in the solution potential caused by the lack of reference can be understood quantitatively, and determine the requirements for accurate measurements in miniaturized systems in the absence of a reference electrode. PMID:25271709

  16. 1 ?m-thickness ultra-flexible and high electrode-density surface electromyogram measurement sheet with 2 V organic transistors for prosthetic hand control.

    PubMed

    Fuketa, Hiroshi; Yoshioka, Kazuaki; Shinozuka, Yasuhiro; Ishida, Koichi; Yokota, Tomoyuki; Matsuhisa, Naoji; Inoue, Yusuke; Sekino, Masaki; Sekitani, Tsuyoshi; Takamiya, Makoto; Someya, Takao; Sakurai, Takayasu

    2014-12-01

    A 64-channel surface electromyogram (EMG) measurement sheet (SEMS) with 2 V organic transistors on a 1 ?m-thick ultra-flexible polyethylene naphthalate (PEN) film is developed for prosthetic hand control. The surface EMG electrodes must satisfy the following three requirements; high mechanical flexibility, high electrode density and high signal integrity. To achieve high electrode density and high signal integrity, a distributed and shared amplifier (DSA) architecture is proposed, which enables an in-situ amplification of the myoelectric signal with a fourfold increase in EMG electrode density. In addition, a post-fabrication select-and-connect (SAC) method is proposed to cope with the large mismatch of organic transistors. The proposed SAC method reduces the area and the power overhead by 96% and 98.2%, respectively, compared with the use of conventional parallel transistors to reduce the transistor mismatch by a factor of 10. PMID:24951707

  17. Considerations on sample holder design and custom-made non-polarizable electrodes for Spectral Induced Polarization measurements on unsaturated soils

    NASA Astrophysics Data System (ADS)

    Kaouane, C.; Chouteau, M. C.; Fauchard, C.; Cote, P.

    2014-12-01

    Spectral Induced Polarization (SIP) is a geophysical method sensitive to water content, saturation and grain size distribution. It could be used as an alternative to nuclear probes to assess the compaction of soils in road works. To evaluate the potential of SIP as a practical tool, we designed an experiment for complex conductivity measurements on unsaturated soil samples.Literature presents a large variety of sample holders and designs, each depending on the context. Although we might find some precise description about the sample holder, exact replication is not always possible. Furthermore, the potential measurements are often done using custom-made Ag/AgCl electrodes and very few indications are given on their reliability with time and temperature. Our objective is to perform complex conductivity measurements on soil samples compacted in a PVC cylindrical mould (10 cm-long, 5 cm-diameter) according to geotechnical standards. To expect homogeneous current density, electrical current is transmitted through the sample via chambers filled with agar gel. Agar gel is a good non-polarizable conductor within the frequency range (1 mHz -20kHz). Its electrical properties are slightly known. We measured increasing of agar-agar electrical conductivity in time. We modelled the influence of this variation on the measurement. If the electrodes are located on the sample, it is minimized. Because of the dimensions at stake and the need for simple design, potential electrodes are located outside the sample, hence the gel contributes to the measurements. Since the gel is fairly conductive, we expect to overestimate the sample conductivity. Potential electrodes are non-polarizable Ag/AgCl electrodes. To avoid any leakage, the KCl solution in the electrodes is replaced by saturated KCl-agar gel. These electrodes are low cost and show a low, stable, self-potential (<1mV). In addition, the technique of making electrode can be easily reproduced and storage and maintenance are simple. We measured a variation of less than 1 mS/m of the electrolyte conductivity during the time of measurement (~1h40) for a conductivity range 25-100 mS/m, showing no ionic contamination of the solution by the electrodes. An improvement to the cell design would be to control the internal temperature of the sample.

  18. High voltage switches having one or more floating conductor layers

    DOEpatents

    Werne, Roger W.; Sampayan, Stephen; Harris, John Richardson

    2015-11-24

    This patent document discloses high voltage switches that include one or more electrically floating conductor layers that are isolated from one another in the dielectric medium between the top and bottom switch electrodes. The presence of the one or more electrically floating conductor layers between the top and bottom switch electrodes allow the dielectric medium between the top and bottom switch electrodes to exhibit a higher breakdown voltage than the breakdown voltage when the one or more electrically floating conductor layers are not present between the top and bottom switch electrodes. This increased breakdown voltage in the presence of one or more electrically floating conductor layers in a dielectric medium enables the switch to supply a higher voltage for various high voltage circuits and electric systems.

  19. Considerations for Estimating Electrode Performance in Li-Ion Cells

    NASA Technical Reports Server (NTRS)

    Bennett, William R.

    2012-01-01

    Advanced electrode materials with increased specific capacity and voltage performance are critical to the development of Li-ion batteries with increased specific energy and energy density. Although performance metrics for individual electrodes are critically important, a fundamental understanding of the interactions of electrodes in a full cell is essential to achieving the desired performance, and for establishing meaningful goals for electrode performance. This paper presents practical design considerations for matching positive and negative electrodes in a viable design. Methods for predicting cell-level discharge voltage, based on laboratory data for individual electrodes, are presented and discussed.

  20. Screen-printed electrode modified with carbon black nanoparticles for phosphate detection by measuring the electroactive phosphomolybdate complex.

    PubMed

    Talarico, Daria; Arduini, Fabiana; Amine, Aziz; Moscone, Danila; Palleschi, Giuseppe

    2015-08-15

    We report a sensor for phosphate detection based on screen-printed electrodes modified with carbon black nanoparticles. The phosphate was measured in amperometric mode via electrochemical reduction of molybdophosphate complex. Carbon black nanoparticles demonstrated the ability to quantify the molybdophosphate complex at a low applied potential. Some analytical parameters such as the working solution (sulfuric acid 0.1M), applied potential (0.125V vs Ag/AgCl), and molybdate concentration (1mM) were optimized. Using these conditions, a linear range of 0.5-100µM was observed with a detection limit of 0.1µM, calculated as three times the standard deviation of the blank divided by the slope of calibration curve. The system was challenged in drinking, river, aquarium, and waste water samples yielding satisfactory recovery values in accordance with a spectrophotometric reference method which demonstrated the suitability of the screen-printed electrode modified with carbon black nanoparticles coupled with the use of molybdate to detect phosphate in water samples. PMID:25966413

  1. Building a Low-Cost, Six-Electrode Instrument to Measure Electrical Properties of Self-Assembled Monolayers of Gold Nanoparticles

    ERIC Educational Resources Information Center

    Gerber, Ralph W.; Oliver-Hoyo, Maria

    2007-01-01

    The development of a new low-cost, six-electrode instrument for measuring the electrical properties of the self-assembled monolayers of gold particles is being described. The system can also be used to measure conductive liquids, except for those that contain aqua region.

  2. Highly Sensitive Measurement of Bio-Electric Potentials by Boron-Doped Diamond (BDD) Electrodes for Plant Monitoring.

    PubMed

    Ochiai, Tsuyoshi; Tago, Shoko; Hayashi, Mio; Fujishima, Akira

    2015-01-01

    We describe a sensitive plant monitoring system by the detection of the bioelectric potentials in plants with boron-doped diamond (BDD) electrodes. For sensor electrodes, we used commercially available BDD, Ag, and Pt plate electrodes. We tested this approach on a hybrid species in the genus Opuntia (potted) and three different trees (ground-planted) at different places in Japan. For the Opuntia, we artificially induced bioelectric potential changes by the surface potential using the fingers. We detected substantial changes in bioelectric potentials through all electrodes during finger touches on the surface of potted Opuntia hybrid plants, although the BDD electrodes were several times more sensitive to bioelectric potential change compared to the other electrodes. Similarly for ground-planted trees, we found that both BDD and Pt electrodes detected bioelectric potential change induced by changing environmental factors (temperature and humidity) for months without replacing/removing/changing electrodes, BDD electrodes were 5-10 times more sensitive in this detection than Pt electrodes. Given these results, we conclude that BDD electrodes on live plant tissue were able to consistently detect bioelectrical potential changes in plants. PMID:26512663

  3. Highly Sensitive Measurement of Bio-Electric Potentials by Boron-Doped Diamond (BDD) Electrodes for Plant Monitoring

    PubMed Central

    Ochiai, Tsuyoshi; Tago, Shoko; Hayashi, Mio; Fujishima, Akira

    2015-01-01

    We describe a sensitive plant monitoring system by the detection of the bioelectric potentials in plants with boron-doped diamond (BDD) electrodes. For sensor electrodes, we used commercially available BDD, Ag, and Pt plate electrodes. We tested this approach on a hybrid species in the genus Opuntia (potted) and three different trees (ground-planted) at different places in Japan. For the Opuntia, we artificially induced bioelectric potential changes by the surface potential using the fingers. We detected substantial changes in bioelectric potentials through all electrodes during finger touches on the surface of potted Opuntia hybrid plants, although the BDD electrodes were several times more sensitive to bioelectric potential change compared to the other electrodes. Similarly for ground-planted trees, we found that both BDD and Pt electrodes detected bioelectric potential change induced by changing environmental factors (temperature and humidity) for months without replacing/removing/changing electrodes, BDD electrodes were 5–10 times more sensitive in this detection than Pt electrodes. Given these results, we conclude that BDD electrodes on live plant tissue were able to consistently detect bioelectrical potential changes in plants. PMID:26512663

  4. Low Actuation Voltage RF MEMS SwitchesWith Signal Frequencies From 0.25GHz to 40GHz

    E-print Network

    Shen, Shyh-Chiang

    voltages. The actuation voltage provides an electrostatic force to make the conductive pad move up and down in a single-pole-double-throw configuration. When a voltage is applied on the bottom electrodes, the pad

  5. Noise investigation of a high precision digital multimeter model HP3457A or HP3458A for microvolt level dc voltage measurements

    NASA Astrophysics Data System (ADS)

    Ueda, Ryuzo; Takajo, Hiroaki; Kazihara, Kazunori

    1999-12-01

    This article examines noise characteristics of a high precision digital multimeter HP3457A or HP3458A by presenting a conceptual but useful model for the generation of zero voltage error under short-circuited input terminals. Two setting states, auto-zero on (AZ-ON) and off (AZ-OFF) are tested and one important conclusion derived is that the state of AZ-OFF has a more extensive potential of performing to the full specifications for measurements of ?V level dc voltage than that of AZ-ON.

  6. Deep-level transient spectroscopy of Al(x)Ga(1-x)As/GaAs using nondestructive acousto-electric voltage measurement

    NASA Technical Reports Server (NTRS)

    Tabib-Azar, Massood; Hajjar, Fares

    1989-01-01

    The amplitude and the transient time constant of the acoustoelectric voltage were measured as a function of temperature to determine the activation energy of deep levels in Al(x)Ga(1-x)As/GaAs grown by molecular-beam epitaxy. In comparison to other methods based on monitoring the capacitance transient, deep-level transient spectroscopy has several advantages. The technique is nondestructive and highly sensitive, and, because of the dependence of the polarity of the acoustoelectric voltage on the carrier type, it yields information about the charge of the transient carriers and the type of deep traps involved in the release or trapping of these carriers.

  7. Effects of skin blood flow and temperature on skin--electrode impedance and offset potential: measurements at low alternating current density.

    PubMed

    Smith, D C

    1992-01-01

    Skin--electrode impedance was determined at 100 Hz and 1 kHz between two disposable electrodes, 5 cm apart, at current densities < 65 microA.cm-2. Measurements were made on the volar skin of the forearm during cooling on cardiopulmonary bypass, and on the dorsum of the foot in the absence of skin blood flow during aortic aneurysm repair. Both the resistive and reactive components of the skin-electrode impedence showed an inverse linear relationship to temperature between 26 and 36 degrees C. The magnitude of the impedance change was different for each patient studied; resistance changes ranged from 0.03 to 23.2 k omega. Degrees C-1 at 100 Hz and from 0.03 to 2.7 k omega. Degrees C-1 at 1 kHz, while reactance changes ranged from 0.4 to 2.1 k omega. Degrees C-1 at 100 Hz and from 0.04 to 0.18 k omega. Degrees C-1 at 1 kHz. Changes in skin-electrode impedance were not due to changes in skin blood flow. There was no consistent change in offset potential with temperature. Although the skin-electrode impedance increases as temperature falls, it is concluded that temperature effects at the skin-electrode interface are not responsible for the observed failure of evoked electromyography during clinical monitoring of neuromuscular function. PMID:1404312

  8. Self-calibrating microfabricated iridium oxide pH electrode array for remote monitoring.

    PubMed

    Carroll, Susan; Baldwin, Richard P

    2010-02-01

    The goal of this work is the development of microfabricated electrochemical sensing systems for environmental, industrial, and security applications requiring long-term unattended operation. The specific advantages of the microfabrication approach include the capability not only to miniaturize the size of the sensor platform but also to create an intelligent design including features such as redundant sensing electrodes, on-chip reference and auxiliary electrodes, and in situ electrode regeneration/calibration. The model system targeted here involves continuous pH monitoring in drinking water at solid-state iridium oxide electrodes. The microchips utilized consist of a flow-through silicon platform (1 cm x 1.2 cm) containing patterned gold electrodes onto which iridium oxide has been deposited electrochemically. To simulate drinking water detection scenarios, sensors are integrated into a flow system. Microfabricated designs include as many as 11 equivalent pH electrodes whose performance was evaluated for factors such as electrode-to-electrode reproducibility, long-term drift, and response to expected interfering agents. With on-chip voltage treatment, absolute potentials measured for an electrode array are within +/-4 mV, with identical (+/-1 mV/pH unit) calibration slopes. This performance level is sustainable over weeks of usage. PMID:20067252

  9. Surface potential measurement of organic thin film on metal electrodes by dynamic force microscopy using a piezoelectric cantilever

    NASA Astrophysics Data System (ADS)

    Satoh, Nobuo; Katori, Shigetaka; Kobayashi, Kei; Watanabe, Shunji; Fujii, Toru; Matsushige, Kazumi; Yamada, Hirofumi

    2011-06-01

    We describe applications of a cantilever with a lead zirconate titanate (PZT) piezoelectric film as self-sensing to dynamic force microscopy (DFM) combined with Kelvin probe force microscopy (KFM). We adopted a frequency modulation (FM) detection method not only to stabilize the imaging conditions in our DFM but also to enhance the sensitivity for the detection of electrostatic forces in KFM measurement. We deposited Alq3 [tris (8-hydroxyquinolinato) aluminum] thin films and aluminum (Al) electrode patterns on an indium tin oxide (ITO)/glass substrate by vacuum evaporation using shadow masks. The surface structures and local surface potential of Alq3 films on metals were investigated using our DFM/KFM instrument to study the local electrical properties at the molecule-metal interface. The photosensitive organic material sample can be in a completely dark environment because no optics are required for cantilever deflection sensing in our experimental setup.

  10. Smartphone-based portable biosensing system using impedance measurement with printed electrodes for 2,4,6-trinitrotoluene (TNT) detection.

    PubMed

    Zhang, Diming; Jiang, Jing; Chen, Junye; Zhang, Qian; Lu, Yanli; Yao, Yao; Li, Shuang; Logan Liu, Gang; Liu, Qingjun

    2015-08-15

    Rapid, sensitive, selective and portable detection of 2,4,6-trinitrotoluene (TNT) is in high demand for public safety and environmental monitoring. In this study, we reported a smartphone-based system using impedance monitoring for TNT detection. The screen-printed electrodes modified with TNT-specific peptides were used as disposable a biosensor to produce impedance responses to TNT. The responses could be monitored by a hand-held device and send out to smartphone through Bluetooth. Then, the smartphone was used to display TNT responses in real time and report concentration finally. In the measurement, the system was demonstrated to detect TNT at concentration as low as 10(-6)M and distinguish TNT versus different chemicals in high specificity. Thus, the smartphone-based biosensing platform provided a convenient and efficient approach to design portable instruments for chemical detections such as TNT recognition. PMID:25796040

  11. Comparing the magnetic resonant coupling radiofrequency stimulation to the traditional approaches: Ex-vivo tissue voltage measurement and electromagnetic simulation analysis

    NASA Astrophysics Data System (ADS)

    Yeung, Sai Ho; Pradhan, Raunaq; Feng, Xiaohua; Zheng, Yuanjin

    2015-09-01

    Recently, the design concept of magnetic resonant coupling has been adapted to electromagnetic therapy applications such as non-invasive radiofrequency (RF) stimulation. This technique can significantly increase the electric field radiated from the magnetic coil at the stimulation target, and hence enhancing the current flowing through the nerve, thus enabling stimulation. In this paper, the developed magnetic resonant coupling (MRC) stimulation, magnetic stimulation (MS) and transcutaneous electrical nerve stimulation (TENS) are compared. The differences between the MRC RF stimulation and other techniques are presented in terms of the operating mechanism, ex-vivo tissue voltage measurement and electromagnetic simulation analysis. The ev-vivo tissue voltage measurement experiment is performed on the compared devices based on measuring the voltage induced by electromagnetic induction at the tissue. The focusing effect, E field and voltage induced across the tissue, and the attenuation due to the increase of separation between the coil and the target are analyzed. The electromagnetic stimulation will also be performed to obtain the electric field and magnetic field distribution around the biological medium. The electric field intensity is proportional to the induced current and the magnetic field is corresponding to the electromagnetic induction across the biological medium. The comparison between the MRC RF stimulator and the MS and TENS devices revealed that the MRC RF stimulator has several advantages over the others for the applications of inducing current in the biological medium for stimulation purposes.

  12. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

  13. Electrode compositions

    DOEpatents

    Block, Jacob (Rockville, MD); Fan, Xiyun (Orange, TX)

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  14. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide.

    PubMed

    Shea, Colleen; Alexoff, David L; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J; Fowler, Joanna S; Qu, Wenchao

    2015-08-01

    In this research, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([(11)C]CN¯) produced by our in-house built automated [(11)C]HCN production system and to identify the major sources of (12)C-cyanide ((12)CN¯). The [(11)C]CN¯ is produced from [(11)C]CO2, which is generated by the (14)N(p,?)(11)C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [(11)C]HCN production system were isolated in order to determine their relative contributions to (12)CN¯ mass. It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33µA for 1 and 10min) did not contribute significantly to the mass. Additionally, we compared the SA of our [(11)C]HCN precursor determined using the ISE to the SA of our current [(11)C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose. PMID:25980658

  15. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide

    SciTech Connect

    Shea, Colleen; Alexoff, David L.; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J.; Fowler, Joanna S.; Qu, Wenchao

    2015-04-25

    In this study, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([11C]CN¯) produced by our in-house built automated [11C]HCN production system and to identify the major sources of 12C-cyanide (12CN¯). The [11C]CN¯ is produced from [11C]CO2, which is generated by the 14N(p,?)11C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [11C]HCN production system were isolated in order to determine their relative contributions to 12CN¯ mass. It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33 µA for 1 and 10 min) did not contribute significantly to the mass. Additionally, we compared the SA of our [11C]HCN precursor determined using the ISE to the SA of our current [11C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose.

  16. Total cyanide mass measurement with micro-ion selective electrode for determination of specific activity of carbon-11 cyanide

    DOE PAGESBeta

    Shea, Colleen; Alexoff, David L.; Kim, Dohyun; Hoque, Ruma; Schueller, Michael J.; Fowler, Joanna S.; Qu, Wenchao

    2015-04-25

    In this study, we aim to directly measure the specific activity (SA) of the carbon-11 cyanide ([11C]CN¯) produced by our in-house built automated [11C]HCN production system and to identify the major sources of 12C-cyanide (12CN¯). The [11C]CN¯ is produced from [11C]CO2, which is generated by the 14N(p,?)11C nuclear reaction using a cyclotron. Direct measurement of cyanide concentrations was accomplished using a relatively inexpensive, and easy to use ion selective electrode (ISE) which offered an appropriate range of sensitivity for detecting mass. Multiple components of the [11C]HCN production system were isolated in order to determine their relative contributions to 12CN¯ mass.more »It was determined that the system gases were responsible for approximately 30% of the mass, and that the molecular sieve/nickel furnace unit contributed approximately 70% of the mass. Beam on target (33 µA for 1 and 10 min) did not contribute significantly to the mass. Additionally, we compared the SA of our [11C]HCN precursor determined using the ISE to the SA of our current [11C]CN¯ derived radiotracers determined by HPLC to assure there was no significant difference between the two methods. These results are the first reported use of an ion selective electrode to determine the SA of no-carrier-added cyanide ion, and clearly show that it is a valuable, inexpensive and readily available tool suitable for this purpose.« less

  17. Electrooptic polymer voltage sensor and method of manufacture thereof

    NASA Technical Reports Server (NTRS)

    Gottsche, Allan (Inventor); Perry, Joseph W. (Inventor)

    1993-01-01

    An optical voltage sensor utilizing an electrooptic polymer is disclosed for application to electric power distribution systems. The sensor, which can be manufactured at low cost in accordance with a disclosed method, measures voltages across a greater range than prior art sensors. The electrooptic polymer, which replaces the optical crystal used in prior art sensors, is sandwiched directly between two high voltage electrodes. Voltage is measured by fiber optical means, and no voltage division is required. The sample of electrooptic polymer is fabricated in a special mold and later mounted in a sensor housing. Alternatively, mold and sensor housing may be identical. The sensor housing is made out of a machinable polymeric material and is equipped with two opposing optical windows. The optical windows are mounted in the bottom of machined holes in the wall of the mold. These holes provide for mounting of the polarizing optical components and for mounting of the fiber optic connectors. One connecting fiber is equipped with a light emitting diode as a light source. Another connecting fiber is equipped with a photodiode as a detector.

  18. Time- and spatially resolved emission spectroscopy of the dielectric barrier discharge for soft ionization sustained by a quasi-sinusoidal high voltage.

    PubMed

    Horvatic, Vlasta; Michels, Antje; Ahlmann, Norman; Jestel, Günter; Veza, Damir; Vadla, Cedomil; Franzke, Joachim

    2015-09-01

    A helium capillary dielectric barrier discharge was investigated by means of time-resolved optical emission spectroscopy with the aim of elucidating the process of the formation of the plasma jet. The helium emission line at 706 nm was utilized to monitor spatial and temporal propagation of the excitation of helium atoms. The discharge was sustained with quasi-sinusoidal high voltage, and the temporal evolution of the helium atomic emission was measured simultaneously with the discharge current. The spatial development of the plasma was investigated along the discharge axis in the whole region, which covers the positions in the capillary between the electrodes as well as the plasma jet outside the capillary. The high voltage electrode was placed 2 mm from the capillary orifice, and the distance between the ground and high voltage electrode was 10 mm. The complete spatiotemporal grid of the development of the helium excitation has shown that during the positive half-period of the applied voltage, two independent plasmas, separated in time, are formed. First, the early plasma that constitutes the plasma jet is formed, while the discharge in the capillary follows subsequently. In the early plasma, the helium atom excitation propagation starts in the vicinity of the high voltage electrode and departs from the capillary towards the ground electrode as well as several millimeters outside of the capillary in the form of the plasma jet. After relatively slow propagation of the early plasma in the capillary and the jet, the second plasma starts between the electrodes. During the negative voltage period, only the plasma in the capillary between the electrodes occurs. PMID:26077750

  19. The LMF triaxial MITL voltage adder system

    SciTech Connect

    Mazarakis, M.G.; Smith, D.L.; Bennett, L.F.; Lockner, T.R.; Olson, R.E.; Poukey, J.W.

    1992-12-31

    The light-ion microfusion driver design consists of multiple accelerating modules fired in coincidence and sequentially in order to provide the desired ion energy, power pulse shape and energy deposition uniformity on an Inertial Confinement Fusion (ICF) target. The basic energy source is a number of Marx generators which, through the appropriate pulse power conditioning, provide the necessary voltage pulse wave form to the accelerating gaps or feeds of each module. The cavity gaps are inductively isolated, and the voltage addition occurs in the center conductor of the voltage adder which is the positive electrode while the electrons of the sheath flow closer to the outer cylinder which is the magnetically insulated cathode electrode. Each module powers a separate two-stage extraction diode which provides a low divergence ion beam. In order to provide the two separate voltage pulses required by the diode, a triaxial adder system is designed for each module. The voltage addition occurs in two separate MITLs. The center hollow cylinder (anode) of the second MITL also serves as the outer cathode electrode for the extension of the first voltage adder MITL. The voltage of the second stage is about twice that of the first stage. The cavities are connected in series to form the outer cylinder of each module. The accelerating modules are positioned radially in a symmetrical way around the fusion chamber. A preliminary conceptual design of the LMF modules with emphasis on the voltage adders and extension MITLs will be presented and discussed.

  20. Cell constant studies of bipolar and tetrapolar electrode systems for impedance measurement

    E-print Network

    Ma, Hanbin; Su, Yang; Nathan, Arokia

    2015-07-26

    ], and the frequency range was from 100 Hz to 1 MHz at room temperature. For each frequency sweep, the measurement time is less than three minutes, and a one second integration time was used between measurements to avoid too much Joule heating in the cell... .H. Grant, Complex permittivity of sodium chloride solutions at microwave frequencies., Bioelectromagnetics. 28 (2007) 264–74. doi:10.1002/bem.20271. [28] Y. Nagasaka, A. Nagashima, Absolute measurement of the thermal conductivity of electrically...

  1. Multifunctional reference electrode

    DOEpatents

    Redey, Laszlo (Lisle, IL); Vissers, Donald R. (Naperville, IL)

    1983-01-01

    A multifunctional, low mass reference electrode of a nickel tube, thermocouple means inside the nickel tube electrically insulated therefrom for measuring the temperature thereof, a housing surrounding the nickel tube, an electrolyte having a fixed sulfide ion activity between the housing and the outer surface of the nickel tube forming the nickel/nickel sulfide/sulfide half-cell. An ion diffusion barrier is associated with the housing in contact with the electrolyte. Also disclosed is a cell using the reference electrode to measure characteristics of a working electrode.

  2. Hybrid dielectric layer for low operating voltages of transparent and flexible organic complementary inverter

    NASA Astrophysics Data System (ADS)

    Go, Mu Seok; Song, Ji-Min; Kim, Chaewon; Lee, Jaegab; Kim, Jiyoung; Lee, Mi Jung

    2015-03-01

    Although flexibility and transparency are considered advantages of organic electronic devices along with low processing cost and the possibility of large-area production, high operating voltages and metallic contacts are obstacles to their application in real electronic products. In this work, flexible and transparent organic complementary inverters that can be operated with low voltage were fabricated on a plastic substrate. Two different air-stable organic semiconductors, fluorinated copper phthalocyanine and pentacene, are used for n-type and p-type transistors, respectively. An ITO gate electrode was deposited by sputtering, and a hybrid dielectric layer with a thin Al2O3 layer and self-assembled monolayers (SAMs) was fabricated to reduce the operation voltage. To confirm the properties of the hybrid dielectric layer, the capacitance and gate leakage current were measured. Then, source and drain electrodes were formed from gold or ITO specifically for fully transparent devices. For the ITO electrodes, a MoO3 interlayer was incorporated between the pentacene and ITO to reduce the contact resistance caused by mismatch of workfunction. Finally, we evaluated the low-voltage operation of the flexible organic inverters and the fully transparent device through transmittance measurement. [Figure not available: see fulltext.

  3. GRAPHITE ELECTRODE FOR THE MEASUREMENT OF REDOX POTENTIAL AND OXYGEN DIFFUSION RATE IN SOIL

    EPA Science Inventory

    The objective of the project was to evaluate control measurements that might be made at land treatment sites to determine the effectiveness of operation in the management of hazardous wastes. Initial studies were on measurement of oxygen concentration and oxygen diffusion rate (O...

  4. Built-in voltage of organic bulk heterojuction p-i-n solar cells measured by electroabsorption spectroscopy

    SciTech Connect

    Siebert-Henze, E. Lyssenko, V. G.; Fischer, J.; Tietze, M.; Brueckner, R.; Schwarze, M.; Vandewal, K.; Ray, D.; Riede, M.; Leo, K.

    2014-04-15

    We investigate the influence of the built-in voltage on the performance of organic bulk heterojuction solar cells that are based on a p-i-n structure. Electrical doping in the hole and the electron transport layer allows to tune their work function and hence to adjust the built-in voltage: Changing the doping concentration from 0.5 to 32 wt% induces a shift of the work function towards the transport levels and increases the built-in voltage. To determine the built-in voltage, we use electroabsorption spectroscopy which is based on an evaluation of the spectra caused by a change in absorption due to an electric field (Stark effect). For a model system with a bulk heterojunction of BF-DPB and C{sub 60}, we show that higher doping concentrations in both the electron and the hole transport layer increase the built-in voltage, leading to an enhanced short circuit current and solar cell performance.

  5. Electrocatalytic Measurement Methodology of Oxide Catalysts Using a Thin-Film Rotating Disk Electrode

    E-print Network

    Suntivich, Jin

    Transition-metal oxides can exhibit high electrocatalytic activity for reactions such as the oxygen reduction reaction (ORR) in alkaline media. It is often difficult to measure and compare the activities of oxide catalysts ...

  6. Electrical property measurements of thin film based Lithium Ion Battery electrodes "Nanostructured Lithium Ion Batteries (LIB) are one of the most promising class of next generation energy

    E-print Network

    Milgram, Paul

    Electrical property measurements of thin film based Lithium Ion Battery electrodes "Nanostructured Lithium Ion Batteries (LIB) are one of the most promising class of next generation energy storage devices materials during the charging/discharging process. However, in previous graphene based LIB battery research

  7. Strain-optic voltage monitor

    SciTech Connect

    Weiss, J.D.

    1995-12-31

    A voltage monitor which uses the shift in absorption edge of crystalline material to measure strain resulting from electric field-induced deformation of piezoelectric or electrostrictive material, providing a simple and accurate means for measuring voltage applied either by direct contact with the crystalline material or by subjecting the material to an electric field.

  8. Single Electrode Would Control Charge-Coupled Device

    NASA Technical Reports Server (NTRS)

    Wadsworth, Mark; Mcgrath, Robert D.

    1989-01-01

    Space saved and interelectrode short circuits eliminated. Proposed virtual-phase, interline-transfer, charge-couple device uses single gate electrode to control both interline and intraline transfer of charge. Voltage on single control electrode varied to transfer charge from photosites to shift register, or else along sift register. Two kinds of transfer independent of each other. Charge transferred along shift register when voltage on control electrode alternated between gate potentials.

  9. Electrical stimulation and electrode properties. Part 2: pure metal electrodes.

    PubMed

    Stevenson, Matthew; Baylor, Kelly; Netherton, Brett L; Stecker, Mark M

    2010-12-01

    Electrical stimulation can cause significant damage to clinical electrodes as well as patient injury. In this study, the effects of stimulation on pure metal electrodes were investigated without the complexities introduced by the multiple elements that make up the clinical electrode. As with the clinical electrodes, there was significant decomposition of pure stainless steel anodes with no associated significant changes in the cathodes when stimulation employed long pulse durations. Effects of stimulation were greater when the anode and cathode were closer under constant voltage stimulation but were distance independent under constant current stimulation. High ionic content of the solution also increased the degree of damage to the anode as did the presence of chloride in the solution. Electrode composition also influenced the amount damage to the anode. Platinum and platinum-iridium electrodes showed no damage with any stimulus while stainless steel showed the lowest resistance to corrosion for direct current (DC) stimulation. Tungsten electrodes behaved very differently than stainless steel, decomposing with pulse stimulation and resisting decomposition during DC stimulation because of the formation of surface protective layers. Because platinum was able to maintain high levels of current over time, prolonged stimulation produced dramatic increases in the temperature of the solution; however, even short periods of stimulation were sufficient to produce dramatic changes in pH in the neighborhood of the electrode. PMID:21313789

  10. Through-the-electrode model of a proton exchange membrane fuel cell with independently measured parameters

    SciTech Connect

    Weisbrod, K.R.; Grot, S.A.; Vandergborgh, N.E.

    1995-09-01

    A one dimensional model for a proton exchange membrane fuel cell was developed which makes use of independently measured parameters for predicting single cell performance. Optimization of catalyst layer formulation and properties are explored. Impact of temperature and cathode pressure upon system performance is investigated.

  11. Development of an electric field application system with transparent electrodes towards the electron EDM measurement with laser-cooled Fr atoms

    NASA Astrophysics Data System (ADS)

    Ishikawa, Taisuke; Ando, Shun; Aoki, Takahiro; Arikawa, Hiroshi; Harada, Ken-Ichi; Hayamizu, Tomohiro; Inoue, Takeshi; Itoh, Masatoshi; Kawamura, Hirokazu; Kato, Ko; Sakamoto, Kosuke; Uchiyama, Aiko; Sakemi, Yasuhiro

    2014-09-01

    The permanent electric dipole moment (EDM) of elementary particles is a good probe for new physics beyond the standard model. Since the francium (Fr) atom has a large enhancement factor of the electron EDM and laser-cooled atoms can have long coherence times, we plan to utilize laser-cooled Fr atoms for the electron EDM search experiment. Besides, a strong electric field is one of key issues for the EDM experiment. Recently, we have embarked on a development of the electric field application system with transparent electrodes coated by tin-doped indium oxide (ITO). The ITO electrodes break the difficulty in the coexistence of electrodes with several cooling laser lights. The actual electric field applied to the atom is evaluated by measuring the dc Stark shift for the laser-cooled rubidium atoms. In this presentation, the present status of the electric field application system will be reported. The permanent electric dipole moment (EDM) of elementary particles is a good probe for new physics beyond the standard model. Since the francium (Fr) atom has a large enhancement factor of the electron EDM and laser-cooled atoms can have long coherence times, we plan to utilize laser-cooled Fr atoms for the electron EDM search experiment. Besides, a strong electric field is one of key issues for the EDM experiment. Recently, we have embarked on a development of the electric field application system with transparent electrodes coated by tin-doped indium oxide (ITO). The ITO electrodes break the difficulty in the coexistence of electrodes with several cooling laser lights. The actual electric field applied to the atom is evaluated by measuring the dc Stark shift for the laser-cooled rubidium atoms. In this presentation, the present status of the electric field application system will be reported. This work is supported by Grants-in-Aid for Scientific Research (No. 26220705) and Tohoku University's Focused Research Project.

  12. Memristor-integrated voltage-stabilizing supercapacitor system.

    PubMed

    Liu, Bin; Liu, Boyang; Wang, Xianfu; Wu, Xinghui; Zhao, Wenning; Xu, Zhimou; Chen, Di; Shen, Guozhen

    2014-08-01

    Voltage-stabilized supercapacitors: A single supercapacitor formed with PCBM/Pt/IPS nanorod-array electrodes is designed and delivers enhanced areal capacitance, capacitance retention, and excellent electrical stability under bending, while a significant voltage-decrease is observed during the discharging process. Once integrated with the memristor, the memristor-integrated supercapacitor systems deliver an extremely low voltage-drop, indicating greatly enhanced voltage-stabilizing features. PMID:24805149

  13. MEMS microswitch for high-voltage applications.

    SciTech Connect

    Strong, Fabian Wilbur

    2004-07-01

    A microswitch utilizing thermoelectric MEMS actuators is being designed, fabricated, and characterized. The switch is intended to switch >1000 VDC with over 100 gigaohms off-state resistance. The main challenge in designing these switches is determining a contact electrode configuration with the ability to stand off high voltages, while still being able to bridge the contact gap using MEMS actuators. Extensive high voltage breakdown testing has confirmed that the breakdown response for planar MEMS polysilicon devices is similar to the published response of larger metal electrodes across single small air gaps (0.5 to 10 um). Investigations of breakdown response in planar electrode configurations with multiple gaps show promising results for high voltage switching.

  14. Atmospheric Pressure Glow Discharge with Liquid Electrode

    NASA Astrophysics Data System (ADS)

    Tochikubo, Fumiyoshi

    2013-09-01

    Nonthermal atmospheric pressure plasmas in contact with liquid are widely studied aiming variety of plasma applications. DC glow discharge with liquid electrode is an easy method to obtain simple and stable plasma-liquid interface. When we focus attention on liquid-phase reaction, the discharge system is considered as electrolysis with plasma electrode. The plasma electrode will supply electrons and positive ions to the liquid surface in a different way from the conventional metal electrode. However, the phenomena at plasma-liquid interface have not been understood well. In this work, we studied physical and chemical effect in liquid induced by dc atmospheric pressure glow discharge with liquid electrode. The experiment was carried out using H-shaped Hoffman electrolysis apparatus filled with electrolyte, to separate the anodic and cathodic reactions. Two nozzle electrodes made of stainless steel are set about 2 mm above the liquid surface. By applying a dc voltage between the nozzle electrodes, dc glow discharges as plasma electrodes are generated in contact with liquid. As electrolyte, we used aqueous solutions of NaCl, Na2SO4, AgNO3 and HAuCl4. AgNO3 and HAuCl4 are to discuss the reduction process of metal ions for synthesis of nanoparticles (NPs). OH radical generation yield in liquid was measured by chemical probe method using terephthalic acid. Discharge-induced liquid flow was visualized by Schlieren method. Electron irradiation to liquid surface (plasma cathode) generated OH- and OH radical in liquid while positive ion irradiation (plasma anode) generated H+ and OH radical. The generation efficiency of OH radical was better with plasma anode. Both Ag NPs in AgNO3 and Au NPs in HAuCl4 were synthesized with plasma cathode while only Au NPs were generated with plasma anode. Possible reaction process is qualitatively discussed. The discharge-induced liquid flow such as convection pattern was strongly influenced by the gas flow on the liquid surface. This work was supported financially in part by Kakenhi (No 2111007), Japan.

  15. The use of multiple EBIC curves and low voltage electron microscopy in the measurement of small diffusion lengths

    NASA Technical Reports Server (NTRS)

    Leon, R. P.

    1987-01-01

    Accurate evaluations of diffusion lengths for heavily to moderately doped III-V semiconductors and/or radiation damaged solar cells have been made possible by using experimental and numerical techniques. The techniques employed were electron beam induced current and low voltage electron microscopy.

  16. Device and method for the measurement of depth of interaction using co-planar electrodes

    DOEpatents

    DeGeronimo, Gianluigi (Syosset, NY)

    2007-09-18

    A device and method for measuring a depth of interaction of an ionizing event and improving resolution of a co-planar grid sensor (CPG) are provided. A time-of-occurrence is measured using a comparator to time the leading edge of the event pulse from the non-collecting or collecting grid. A difference signal between the grid signals obtained with a differential amplifier includes a pulse with a leading edge occurring at the time-of-detection, measured with another comparator. A timing difference between comparator outputs corresponds to the depth of interaction, calculated using a processor, which in turn weights the difference grid signal to improve spectral resolution of a CPG sensor. The device, which includes channels for grid inputs, may be integrated into an Application Specific Integrated Circuit. The combination of the device and sensor is included. An improved high-resolution CPG is provided, e.g., a gamma-ray Cadmium Zinc Telluride CPG sensor operating at room temperature.

  17. Measurements of stray antenna capacitance in the STEREO/WAVES instrument: Comparison of the measured voltage spectrum with an antenna electron shot noise model

    NASA Astrophysics Data System (ADS)

    Zouganelis, I.; Maksimovic, M.; Meyer-Vernet, N.; Bale, S. D.; Eastwood, J. P.; Zaslavsky, A.; Dekkali, M.; Goetz, K.; Kaiser, M. L.

    2010-02-01

    One of the most accurate techniques for in situ measuring the electron density and temperature in space plasmas is the quasi-thermal noise spectroscopy, which uses the voltage fluctuation spectrum on an electric antenna. This technique has been used successfully on the WIND and ULYSSES spacecraft; however, on STEREO this technique may only work in high-density filamentary structures, where the Debye length is small, because the STEREO/WAVES antennas have a large surface area, so that the resulting shot noise spectrum in the solar wind dominates the power at lower frequencies. In the unperturbed solar wind, we can use instead the electron shot noise to infer the plasma density. For doing so, we use well calibrated WIND particle data to deduce the stray capacitance of the STEREO/WAVES antenna system in a special configuration when the STEREO-B spacecraft was just downstream of WIND. This stray capacitance is also compared to ground experiments done on the flight spare equipment and independent calibrations performed using the galactic radio background.

  18. Linear inductive voltage adders (IVA) for advanced hydrodynamic radiography

    SciTech Connect

    Mazarakis, M.G.; Boyes, J.D.; Johnson, D.L.

    1998-09-01

    The electron beam which drifts through the multiple cavities of conventional induction linacs (LIA) is replaced in an IVA by a cylindrical metal conductor which extends along the entire length of the device and effectuates the addition of the accelerator cavity voltages. In the approach to radiography, the linear inductive voltage adder drives a magnetically immersed electron diode with a millimeter diameter cathode electrode and a planar anode/bremsstrahlung converter. Both anode and cathode electrodes are immersed in a strong (15--50 T) solenoidal magnetic field. The electron beam cross section is approximately of the same size as the cathode needle and generates a similar size, very intense x-ray beam when it strikes the anode converter. An IVA driven diode can produce electron beams of equal size and energy as a LIA but with much higher currents (40--50 kA versus 4--5 kA), simpler hardware and thus lower cost. The authors present here first experimental validations of the technology utilizing HERMES 3 and SABRE IVA accelerators. The electron beam voltage and current were respectively of the order of 10 MV and 40 kA. X-ray doses of up to 1 kR {at} 1 m and spot sizes as small as 1.7 mm (at 200 R doses) were measured.

  19. Extraction of a strongly focusing He{sup +} beam from three-stage concave electrodes for alpha particle measurement system in ITER

    SciTech Connect

    Kobuchi, T.; Kisaki, M.; Tsumori, K.; Kaneko, O.; Sasao, M.; Tanaka, N.; Okamoto, A.; Kitajima, S.; Shinto, K.; Wada, M.

    2012-02-15

    A strongly focusing He{sup +} ion beam source equipped with concave multi-aperture electrodes was developed for production of He{sup -} through a charge exchange cell. The beam was extracted at a voltage less than 20 kV from 301 apertures distributed in an area of 100 mm {phi}, and focused at 750 mm distance. The beam current and the beam size of 2 A and 20 mm in diameter, respectively, were achieved with an arc power less than 10 kW. The optimum perveance was obtained at 0.02 A/kV{sup 1.5} at the beam energy less than 20 keV which is suitable for the conversion to He{sup -} in an alkali vapor cell.

  20. Methods and apparatus for measurement of electronic properties of geological formations through borehole casing

    DOEpatents

    Vail, III, William B. (Bothell, WA)

    1989-01-01

    Methods and apparatus are provided for measuring electronic properties of geological formations and cement layers adjacent to cased boreholes including resistivities, polarization phenomena and dielectric constants. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. At least three voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of differential current conducted into formation in the vicinity of those electrodes. These measurements facilitate calculation of the resistivities of the adjacent geological formations as well as an indication of whether cement is present. Measurements of the differential voltage response to transient currents provide a measurement of the polarization phenomena in formation as well as the capacitance of the casing in contact with the formation which is useful for determining whether oil and gas are present. Lithological characteristics of the formation such as the presence or absence of clay can also be determined. A calibration procedure is provided for minimizing errors induced by variations in the casing. The device also may be placed within the pipe attached to a drill bit while drilling open holes.

  1. Methods and apparatus for measurement of electronic properties of geological formations through borehole casing

    DOEpatents

    Vail, W.B. III.

    1989-11-21

    Methods and apparatus are provided for measuring electronic properties of geological formations and cement layers adjacent to cased boreholes including resistivities, polarization phenomena and dielectric constants. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. At least three voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of differential current conducted into formation in the vicinity of those electrodes. These measurements facilitate calculation of the resistivities of the adjacent geological formations as well as an indication of whether cement is present. Measurements of the differential voltage response to transient currents provide a measurement of the polarization phenomena in formation as well as the capacitance of the casing in contact with the formation which is useful for determining whether oil and gas are present. Lithological characteristics of the formation such as the presence or absence of clay can also be determined. A calibration procedure is provided for minimizing errors induced by variations in the casing. The device also may be placed within the pipe attached to a drill bit while drilling open holes. 48 figs.

  2. Methods and apparatus for measurement of electronic properties of geological formations through borehole casing

    DOEpatents

    Vail, W.B. III.

    1991-08-27

    Methods and apparatus are provided for measuring electronic properties of geological formations and cement layers adjacent to cased boreholes including resistivities, polarization phenomena and dielectric constants. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. At least three voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the differential current conducted into the formation in the vicinity of those electrodes. These measurements facilitate calculation of the resistivities of the adjacent geological formations as well as an indication of whether cement is present. Measurements of the differential voltage response to transient currents provide a measurement of the polarization phenomena in formation as well as the capacitance of the casing in contact with the formation which is useful for determining whether oil and gas are present. Lithological characteristics of the formation such as the presence or absence of clay can also be determined. A calibration procedure is provided for minimizing errors induced by variations in the casing. The device also may be placed within the pipe attached to a drill bit while drilling open holes. 48 figures.

  3. Methods and apparatus for measurement of electronic properties of geological formations through borehole casing

    DOEpatents

    Vail, III, William B. (Bothell, WA)

    1991-01-01

    Methods and apparatus are provided for measuring electronic properties of geological formations and cement layers adjacent to cased boreholes including resistivities, polarization phenomena and dielectric constants. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. At least three voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the differential current conducted into formation in the vicinity of those electrodes. These measurements facilitate calculation of the resistivities of the adjacent geological formations as well as an indication of whether cement is present. Measurements of the differential voltage response to transient currents provide a measurement of the polarization phenomena in formation as well as the capacitance of the casing in contact with the formation which is useful for determining whether oil and gas present. Lithological characteristics of the formation such as the pressence or absence of clay can also be determined. A calibration procedure is provided for minimizing errors induced by variations in the casing. The device also may be placed within the pipe attached to a drill bit while drilling open holes.

  4. Acetylcholinesterase biosensor for inhibitor measurements based on glassy carbon electrode modified with carbon black and pillar[5]arene.

    PubMed

    Shamagsumova, Rezeda V; Shurpik, Dmitry N; Padnya, Pavel L; Stoikov, Ivan I; Evtugyn, Gennady A

    2015-11-01

    New acetylcholinesterase (AChE) biosensor based on unsubstituted pillar[5]arene (P[5]A) as electron mediator was developed and successfully used for highly sensitive detection of organophosphate and carbamate pesticides. The AChE from electric eel was immobilized by carbodiimide binding on carbon black (CB) placed on glassy carbon electrode. The working potential of 200mV was obtained in chronoamperometric mode with the measurement time of 180s providing best inter-biosensors precision of the results. The AChE biosensor developed made it possible to detect 1×10(-11)-1×10(-6)M of malaoxon, 1×10(-)(8)-7×10(-6)M of methyl-paraoxon, 1×10(-10)-2×10(-6)M of carbofuran and 7×10(-9)-1×10(-5)M of aldicarb with 10min incubation. The limits of detection were 4×10(-12), 5×10(-9), 2×10(-11) and 6×10(-10)M, respectively. The AChE biosensor was tested in the analysis of pesticide residuals in spiked samples of peanut and beetroot. The protecting effect of P[5]A derivative bearing quaternary ammonia groups on malaoxon inhibition was shown. PMID:26452862

  5. Study on electrical characteristics of barrier-free atmospheric air diffuse discharge generated by nanosecond pulses and long wire electrodes

    SciTech Connect

    Li, Lee Liu, Yun-Long; Teng, Yun; Liu, Lun; Pan, Yuan

    2014-07-15

    In room-temperature atmospheric air, the large-scale diffuse plasmas can be generated via high-voltage nanosecond pulses with short rise-time and wire electrodes. Diffuse discharge with the wire electrode length up to 110.0?cm and the discharge spacing of several centimeters has been investigated in this paper. Electrical characteristics of diffuse discharge have been analyzed by their optical photographs and measuring of the voltage and current waveforms. Experimental results show the electrode spacing, and the length of wire electrodes can influence the intensity and mode transition of diffuse discharge. The characteristic of current waveforms is that there are several current oscillation peaks at the time of applied pulsed voltage peak, and at the tail of applied pulse, the conduction current component will compensate the displacement one so that the measured current is unidirectional in diffuse discharge mode. The transition from diffuse discharge to arc discharge is always with the increasing of conduction current density. As for nanosecond pulses with long tail, the long wire electrodes are help for generating non-equilibrium diffuse plasmas.

  6. High-Voltage Droplet Dispenser

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.

    2003-01-01

    An apparatus that is extremely effective in dispensing a wide range of droplets has been developed. This droplet dispenser is unique in that it utilizes a droplet bias voltage, as well as an ionization pulse, to release a droplet. Apparatuses that deploy individual droplets have been used in many applications, including, notably, study of combustion of liquid fuels. Experiments on isolated droplets are useful in that they enable the study of droplet phenomena under well-controlled and simplified conditions. In this apparatus, a syringe dispenses a known value of liquid, which emerges from, and hangs onto, the outer end of a flat-tipped, stainless steel needle. Somewhat below the needle tip and droplet is a ring electrode. A bias high voltage, followed by a high-voltage pulse, is applied so as to attract the droplet sufficiently to pull it off the needle. The voltages are such that the droplet and needle are negatively charged and the ring electrode is positively charged.

  7. An evaluation of the contribution of radiation diffusion to thermal conductivity in high-pressure discharge lamps from operating-voltage and wall-temperature measurements

    NASA Astrophysics Data System (ADS)

    Born, M.

    1999-04-01

    The contribution of the radiation diffusion 0022-3727/32/8/007/img1 to the thermal conductivity 0022-3727/32/8/007/img2 in high-pressure discharge lamps is evaluated from operating-voltage and wall-temperature measurements for several cylindrical ceramic discharge tubes filled with mercury and argon as the rare gas. From calculations of 0022-3727/32/8/007/img1 using spectral line data of mercury, it is shown that the electrical conductivity 0022-3727/32/8/007/img4 can be well represented by a linear function of the heat-flux potential S. Under this assumption, the energy balance can be solved analytically and plasma parameters, i.e. radiation-diffusion and plasma-temperature profiles, can be calculated from the operating voltage and wall temperature without knowledge of spectral lines. The results are in good agreement with numerical calculations of the energy balance involving calculation of the radiation diffusion from spectral line data. The method may also be applied to other buffer gases for which there is a linear dependency of 0022-3727/32/8/007/img5. This may be checked qualitatively by measurement of the temporal evolution of the operating voltage using the Cassie-Francis equation.

  8. A systematic study of BNL's 3D-Trench Electrode detectors

    NASA Astrophysics Data System (ADS)

    Montalbano, A.; Bassignana, D.; Li, Z.; Liu, S.; Lynn, D.; Pellegrini, G.; Tsybychev, D.

    2014-11-01

    New types of silicon pixel detectors have been proposed because of the need for more radiation hard semiconductor devices for the high luminosity tracking detector upgrades at the Large Hadron Collider. A novel type of 3D Si pixel detectors is proposed, with each cell of the 3D-Trench Electrode pixel detector featuring a concentric trench electrode surrounding the central collecting column electrode. The pixel sensor is an array of those individual cells. Systematic 3D simulations using Silvacos TCAD programs have been carried out to study the characteristics of this novel 3D pixel design and to compare to the traditional 3D column electrode pixel design. The 3D simulations show a much lower depletion voltage and a more uniform electric field in the new 3D-Trench Electrode pixel detectors as compared to the traditional 3D column Electrode detectors. The first prototype 3D-Trench Electrode pixel detectors have been manufactured at the Centro Nacional De Microelectronica. Preliminary electrical measurements are discussed and charge collection efficiency measurements are presented.

  9. Method of making biocompatible electrodes

    DOEpatents

    Wollam, John S. (Acton, MA)

    1992-01-01

    A process of improving the sensing function of biocompatible electrodes and the product so made are disclosed. The process is designed to alter the surfaces of the electrodes at their tips to provide increased surface area and therefore decreased contact resistance at the electrode-tissue interface for increased sensitivity and essentially includes rendering the tips atomically clean by exposing them to bombardment by ions of an inert gas, depositing an adhesion layer on the cleaned tips, forming a hillocked layer on the adhesion layer by increasing the temperature of the tips, and applying a biocompatible coating on the hillocked layer. The resultant biocompatible electrode is characterized by improved sensitivity, minimum voltage requirement for organ stimulation and a longer battery life for the device in which it is employed.

  10. Field-enhanced electrodes for additive-injection non-thermal plasma (NTP) processor

    DOEpatents

    Rosocha, Louis A. (Los Alamos, NM); Ferreri, Vincent (Westminster, CO); Kim, Yongho (Los Alamos, NM)

    2009-04-21

    The present invention comprises a field enhanced electrode package for use in a non-thermal plasma processor. The field enhanced electrode package includes a high voltage electrode and a field-enhancing electrode with a dielectric material layer disposed in-between the high voltage electrode and the field-enhancing electrode. The field-enhancing electrode features at least one raised section that includes at least one injection hole that allows plasma discharge streamers to occur primarily within an injected additive gas.

  11. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    SciTech Connect

    J. Grames, R. Suleiman, P.A. Adderley, J. Clark, J. Hansknecht, D. Machie, M. Poelker, M.L. Stutzman

    2011-04-01

    GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion damage over a larger area, and (d) by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  12. Electrode structure and methods of making same

    DOEpatents

    Ruud, James Anthony; Browall, Kenneth Walter; Rehg, Timothy Joseph; Renou, Stephane; Striker, Todd-Michael

    2010-04-06

    A method of making an electrode structure is provided. The method includes disposing an electrocatalytic material on an electrode, applying heat to the electrocatalytic material to form a volatile oxide of the electrocatalytic material, and applying a voltage to the electrode to reduce the volatile oxide to provide a number of nano-sized electrocatalytic particles on or proximate to a triple phase boundary, where the number of nano-sized electrocatalytic particles is greater on or proximate to the triple phase boundary than in an area that is not on or proximate to the triple phase boundary, and where the triple phase boundary is disposed on the electrode.

  13. Fiber Optic High Voltage Probe

    SciTech Connect

    Matthew J. Heino

    1999-08-01

    We developed a fiber coupled sensor to measure High Voltage directly using only light as the probe. We use the Pockles effect in lithium niobate crystal which will induce a phase shift in a laser beam that varies according to applied voltage. This can then be transformed into a modulation of beam intensity by polarizers, interferometery, or waveguide coupling. No voltage dividers are necessary, nor is any physical connection. This is accompanied by taking advantage of the structure of the power system itself, using voltage planes and dielectric insulation already present as the capacitive voltage divider. We hypothesize a bandwidth from GHz to DC. Such a system could be used in any application that calls for isolated and unobtrusive voltage sensing.

  14. Pulsed voltage electrospray ion source and method for preventing analyte electrolysis

    DOEpatents

    Kertesz, Vilmos (Knoxville, TN); Van Berkel, Gary (Clinton, TN)

    2011-12-27

    An electrospray ion source and method of operation includes the application of pulsed voltage to prevent electrolysis of analytes with a low electrochemical potential. The electrospray ion source can include an emitter, a counter electrode, and a power supply. The emitter can include a liquid conduit, a primary working electrode having a liquid contacting surface, and a spray tip, where the liquid conduit and the working electrode are in liquid communication. The counter electrode can be proximate to, but separated from, the spray tip. The power system can supply voltage to the working electrode in the form of a pulse wave, where the pulse wave oscillates between at least an energized voltage and a relaxation voltage. The relaxation duration of the relaxation voltage can range from 1 millisecond to 35 milliseconds. The pulse duration of the energized voltage can be less than 1 millisecond and the frequency of the pulse wave can range from 30 to 800 Hz.

  15. Electron launching voltage monitor

    DOEpatents

    Mendel, Clifford W. (Albuquerque, NM); Savage, Mark E. (Albuquerque, NM)

    1992-01-01

    An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors.

  16. Application of carbon nanotube hold-off voltage for determining gas composition

    NASA Technical Reports Server (NTRS)

    Schipper, John F. (Inventor); Li, Jing (Inventor)

    2009-01-01

    Method and system for determining chemical composition of a single-component or multiple-component gas, using a discharge holdoff mechanism. A voltage difference V between two spaced apart electrodes is brought to a selected value and held, the holdoff time interval .DELTA.t(V;ho) required before gas discharge occurs is measured, and the associated electrical current or cumulative electrical charge is measured. As the voltage difference V increases, the time interval length .DELTA.t(V;ho) decreases monotonically. Particular voltage values, V.sub..infin. and V.sub.0, correspond to initial appearance of discharge (.DELTA.t.apprxeq..infin.) and prompt discharge (.DELTA.t.apprxeq.0). The values V.sub..infin. and V.sub.0 and the rate of decrease of .DELTA.t(V;ho) and/or the rate of increase of current or cumulative charge with increasing V are characteristic of one or more gas components present.

  17. Measuring of electrical changes induced by in situ combustion through flow-through electrodes in a laboratory sample of core material

    DOEpatents

    Lee, David O. (Albuquerque, NM); Montoya, Paul C. (Albuquerque, NM); Wayland, Jr., James R. (Albuquerque, NM)

    1986-01-01

    Method and apparatus are provided for obtaining accurate dynamic measurements for passage of phase fronts through a core sample in a test fixture. Flow-through grid structures are provided for electrodes to permit data to be obtained before, during and after passage of a front therethrough. Such electrodes are incorporated in a test apparatus for obtaining electrical characteristics of the core sample. With the inventive structure a method is provided for measurement of instabilities in a phase front progressing through the medium. Availability of accurate dynamic data representing parameters descriptive of material characteristics before, during and after passage of a front provides a more efficient method for enhanced recovery of oil using a fire flood technique.

  18. Measuring of electrical changes induced by in situ combustion through flow-through electrodes in a laboratory sample of core material

    DOEpatents

    Lee, D.O.; Montoya, P.C.; Wayland, J.R. Jr.

    1986-12-09

    Method and apparatus are provided for obtaining accurate dynamic measurements for passage of phase fronts through a core sample in a test fixture. Flow-through grid structures are provided for electrodes to permit data to be obtained before, during and after passage of a front there through. Such electrodes are incorporated in a test apparatus for obtaining electrical characteristics of the core sample. With the inventive structure a method is provided for measurement of instabilities in a phase front progressing through the medium. Availability of accurate dynamic data representing parameters descriptive of material characteristics before, during and after passage of a front provides a more efficient method for enhanced recovery of oil using a fire flood technique. 12 figs.

  19. Differential B-dot and D-dot monitors for current and voltage measurements on a 20-MA 3-MV pulsed-power accelerator.

    SciTech Connect

    Shoup, Roy Willlam; Gilliland, Terrance Leo; Lee, James R.; Speas, Christopher Shane; Kim, Alexandre A.; Struve, Kenneth William; York, Mathew William; Leifeste, Gordon T.; Rochau, Gregory Alan; Sharpe, Arthur William; Stygar, William A.; Porter, John Larry Jr.; Wagoner, Tim C.; Reynolds, Paul Gerard; Slopek, Jeffrey Scott; Moore, William B. S.; Dinwoodie, Thomas Albert; Woodring, R. M.; Broyles, Robin Scott; Mills, Jerry Alan; Melville, J. A.; Dudley, M. E.; Androlewicz, K. E.; Mourning, R. W.; Moore, J. K.; Serrano, Jason Dimitri; Ives, H. C.; Johnson, M. F.; Peyton, B. P.; Leeper, Ramon Joe; Savage, Mark Edward; Donovan, Guy Louis; Spielman, R. B.; Seamen, Johann F.

    2007-12-01

    We have developed a system of differential-output monitors that diagnose current and voltage in the vacuum section of a 20-MA 3-MV pulsed-power accelerator. The system includes 62 gauges: 3 current and 6 voltage monitors that are fielded on each of the accelerator's 4 vacuum-insulator stacks, 6 current monitors on each of the accelerator's 4 outer magnetically insulated transmission lines (MITLs), and 2 current monitors on the accelerator's inner MITL. The inner-MITL monitors are located 6 cm from the axis of the load. Each of the stack and outer-MITL current monitors comprises two separate B-dot sensors, each of which consists of four 3-mm-diameter wire loops wound in series. The two sensors are separately located within adjacent cavities machined out of a single piece of copper. The high electrical conductivity of copper minimizes penetration of magnetic flux into the cavity walls, which minimizes changes in the sensitivity of the sensors on the 100-ns time scale of the accelerator's power pulse. A model of flux penetration has been developed and is used to correct (to first order) the B-dot signals for the penetration that does occur. The two sensors are designed to produce signals with opposite polarities; hence, each current monitor may be regarded as a single detector with differential outputs. Common-mode-noise rejection is achieved by combining these signals in a 50-{Omega} balun. The signal cables that connect the B-dot monitors to the balun are chosen to provide reasonable bandwidth and acceptable levels of Compton drive in the bremsstrahlung field of the accelerator. A single 50-{omega} cable transmits the output signal of each balun to a double-wall screen room, where the signals are attenuated, digitized (0.5-ns/sample), numerically compensated for cable losses, and numerically integrated. By contrast, each inner-MITL current monitor contains only a single B-dot sensor. These monitors are fielded in opposite-polarity pairs. The two signals from a pair are not combined in a balun; they are instead numerically processed for common-mode-noise rejection after digitization. All the current monitors are calibrated on a 76-cm-diameter axisymmetric radial transmission line that is driven by a 10-kA current pulse. The reference current is measured by a current-viewing resistor (CVR). The stack voltage monitors are also differential-output gauges, consisting of one 1.8-cm-diameter D-dot sensor and one null sensor. Hence, each voltage monitor is also a differential detector with two output signals, processed as described above. The voltage monitors are calibrated in situ at 1.5 MV on dedicated accelerator shots with a short-circuit load. Faraday's law of induction is used to generate the reference voltage: currents are obtained from calibrated outer-MITL B-dot monitors, and inductances from the system geometry. In this way, both current and voltage measurements are traceable to a single CVR. Dependable and consistent measurements are thus obtained with this system of calibrated diagnostics. On accelerator shots that deliver 22 MA to a low-impedance z-pinch load, the peak lineal current densities at the stack, outer-MITL, and inner-MITL monitor locations are 0.5, 1, and 58 MA/m, respectively. On such shots the peak currents measured at these three locations agree to within 1%.

  20. A voltammetric method of measuring the specific surface area and amount of platinum in microsamples of electrode material and membrane-electrode assembly of hydrogen fuel cells

    NASA Astrophysics Data System (ADS)

    Nechitailov, A. A.; Glebova, N. V.; Krasnova, A. O.; Tomasov, A. A.; Zelenina, N. K.

    2015-07-01

    A method based on cyclic voltammetry is proposed for determining platinum content, measuring the specific area of the active surface of platinum nanoparticles, and studying the dynamics of these values in a small amount (micrograms) of sample material.

  1. A battery-based, low-noise voltage source

    NASA Astrophysics Data System (ADS)

    Wagner, Anke; Sturm, Sven; Schabinger, Birgit; Blaum, Klaus; Quint, Wolfgang

    2010-06-01

    A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of ±15 and ±5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7×10-7 over 6.5 h and a noise level equal or smaller than 30 nV/?Hz is achieved.

  2. Ac loss modelling and measurement of superconducting transformers with coated-conductor Roebel-cable in low-voltage winding

    NASA Astrophysics Data System (ADS)

    Pardo, Enric; Staines, Mike; Jiang, Zhenan; Glasson, Neil

    2015-11-01

    Power transformers using a high temperature superconductor (HTS) ReBCO coated conductor and liquid nitrogen dielectric have many potential advantages over conventional transformers. The ac loss in the windings complicates the cryogenics and reduces the efficiency, and hence it needs to be predicted in its design, usually by numerical calculations. This article presents detailed modelling of superconducting transformers with Roebel cable in the low-voltage (LV) winding and a high-voltage (HV) winding with more than 1000 turns. First, we model a 1 MVA 11 kV/415 V 3-phase transformer. The Roebel cable solenoid forming the LV winding is also analyzed as a stand-alone coil. Agreement between calculations and experiments of the 1 MVA transformer supports the model validity for a larger tentative 40 MVA 110 kV/11 kV 3-phase transformer design. We found that the ac loss in each winding is much lower when it is inserted in the transformer than as a stand-alone coil. The ac loss in the 1 and 40 MVA transformers is dominated by the LV and HV windings, respectively. Finally, the ratio of total loss over rated power of the 40 MVA transformer is reduced below 40% of that of the 1 MVA transformer. In conclusion, the modelling tool in this work can reliably predict the ac loss in real power applications.

  3. Photoconductivity of high-voltage space insulating materials

    NASA Technical Reports Server (NTRS)

    Coffey, H. T.; Nanevicz, J. E.; Adamo, R. C.

    1975-01-01

    The dark and photoconductivities of four high voltage spacecraft insulators, Kapton-H, FEP Teflon, Parylene, and fused quartz, were studied under a variety of conditions intended to simulate a space environment. All measurements were made in a vacuum of less than .00001 torr while the temperature was varied from 22 C to 100 C. Some of the samples used employed conventional deposited metal electrodes--others employed electrodes composed either of an electron beam or a plasma formed by ionization of the residual gas in the test chamber. Test results show: (1) Kapton had unusual conduction properties; it conductivity decreased by more than an order of magnitude when heated at 100 C in a vacuum, but ultimately attained a stable and reproducible value. (2) Both Teflon and fused quartz had high dark resistivities but low photoresistivities when exposed to UV. Optical-density measurements revealed that both materials transmitted UV with little attenuation. (3) Parylene was found to have a low but relatively stable resistivity--comparatively minor changes occurred upon heating or illuminating the sample. Optical-density measurements showed that Parylene was absorbent in the UV and would prevent photoemission from the metal electrode on the back surface.

  4. "Wormhole" geometry for entrapping topologically protected qubits in non-abelian quantum hall states and probing them with voltage and noise measurements.

    PubMed

    Hou, Chang-Yu; Chamon, Claudio

    2006-10-01

    We study a tunneling geometry defined by a single point-contact constriction that brings to close vicinity two points sitting at the same edge of a quantum Hall liquid, shortening the trip between the otherwise spatially separated points along the normal chiral edge path. This wormhole-like geometry allows for entrapping bulk quasiparticles between the edge path and the tunnel junction, possibly realizing a topologically protected qubit if the quasiparticles have non-Abelian statistics. We show how either noise or simpler voltage measurements along the edge can probe the non-Abelian nature of the trapped quasiparticles. PMID:17155280

  5. Inexpensive and Disposable pH Electrodes

    ERIC Educational Resources Information Center

    Goldcamp, Michael J.; Conklin, Alfred; Nelson, Kimberly; Marchetti, Jessica; Brashear, Ryan; Epure, Emily

    2010-01-01

    Inexpensive electrodes for the measurement of pH have been constructed using the ionophore tribenzylamine for sensing H[superscript +] concentrations. Both traditional liquid-membrane electrodes and coated-wire electrodes have been constructed and studied, and both exhibit linear, nearly Nernstian responses to changes in pH. Measurements of pH…

  6. Electrical Effect in Silver-Point Realization Due to Cell Structure and Bias Voltage Based on Resistance Measurement Using AC and DC Bridges

    NASA Astrophysics Data System (ADS)

    Widiatmo, J. V.; Harada, K.; Yamazawa, K.; Tamba, J.; Arai, M.

    2015-08-01

    Electrical effects related to insulating leakage represent one of the major factors contributing to uncertainties in measurements using high-temperature standard platinum resistance thermometers (HTSPRTs), especially during the realization of the silver freezing point (). This work is focused on the evaluation of the differences in resistance measurements observed when using AC resistance bridges and DC resistance bridges, hereafter, termed the AC-DC differences, as the result of various electrical effects. The magnitude of the AC-DC difference in several silver-point cells is demonstrated with several HTSPRTs. The effect of the cell structure on the AC-DC difference is evaluated by exchanging some components, part by part, within a silver-point cell. Then, the effect of the bias voltage applied to the heat pipe within the silver-point furnace is evaluated. Through the analysis of the experimental results and comparison with the reports in the literature, the importance of evaluating the AC-DC difference as a means to characterize the underlying electrical effects is discussed, considering that applying a negative bias condition to the furnace with respect to the high-temperature SPRT can minimize the AC-DC difference. Concluding recommendations are proposed on the components used in silver-point cells and the application of a bias voltage to the measurement circuit to minimize the effects of the electrical leakage.

  7. Low Voltage Spatial Light Modulator

    SciTech Connect

    Papavasiliou, A

    2003-02-19

    This project studied the feasibility of a Low-Voltage actuator technology that promises to reduce the switched voltage requirements and linearize the response of spatial light modulators. We created computer models that demonstrate substantial advantages offered by this technology, and fabricated and tested those devices. SLMs are electro-optic devices for modulating the phase, amplitude or angle of light beams, laser or other. Applications for arrays of SLMs include turbulence correction for high-speed optical communications, imaging through distorting media, input devices for holographic memories, optical manipulation of DNA molecules, and optical computers. Devices based on micro electro-mechanical systems (MEMS) technology have recently become of special interest because of their potential for greatly improved performance at a much lower cost than piezoelectric or liquid crystal based devices. The new MEMS-based SLM devices could have important applications in high-speed optical communication and remote optical sensing, in support of DoD and DOE missions. Virtually all previously demonstrated MEMS SLMs are based on parallel-plate capacitors where an applied voltage causes a mirror attached to a suspended electrode to move towards a fixed electrode. They require relatively high voltages, typically on the order of 100 V, resulting in (1) large transistor sizes, available only from specialized foundries at significant cost and limiting the amount/sophistication of electronics under each SLM pixel, and (2) large power dissipation/area, resulting in a heat removal issue because of the optical precision required ({approx} 1/50-th of a wavelength). The actuator described in this process uses an advanced geometry that was invented at LLNL and is currently still proprietary. The new geometry allows the application of a bias voltage. This applied bias voltage results in a reduction of the required switched voltage and a linearization of the response curve. When this advanced actuator is coupled with non-linear springs, the response curve becomes even more linear. The response curve of the springs is tailored to produce an actuator with extremely linear displacement vs. voltage characteristics.

  8. Reorientation Response of Magnetic Microspheres Attached to Gold Electrodes Under an Applied Magnetic Field

    NASA Astrophysics Data System (ADS)

    De Los Santos Valladares, L.; Dominguez, A. Bustamante; Aguiar, J. Albino; Reeve, R. M.; Mitrelias, T.; Langford, R. M.; Azuma, Y.; Barnes, C. H. W.; Majima, Y.

    2013-08-01

    In this work, we report the mechanical reorientation of thiolated ferromagnetic microspheres bridging a pair of gold electrodes under an external magnetic field. When an external magnetic field (7 kG) is applied during the measurement of the current-voltage characteristics of a carboxyl ferromagnetic microsphere (4 ?m diameter) attached to two gold electrodes by self-assembled monolayers (SAMs) of octane dithiol (C8H18S2), the current signal is distorted. Rather than due to magnetoresistance, this effect is caused by a mechanical reorientation of the ferromagnetic sphere, which alters the number of SAMs between the sphere and the electrodes and therefore affects conduction. To study the physical reorientation of the ferromagnetic particles, we measure their hysteresis loops while suspended in a liquid solution.

  9. Activated transport in AMTEC electrodes

    SciTech Connect

    Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O`Connor, D.; Kikkert, S.

    1992-07-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

  10. Activated transport in AMTEC electrodes

    SciTech Connect

    Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O'Connor, D.; Kikkert, S.

    1992-01-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

  11. Activated transport in AMTEC electrodes

    NASA Astrophysics Data System (ADS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; Oconnor, D.; Kikkert, S.

    1992-08-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of the diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process.

  12. Measurements of photocathode operational lifetime at beam currents up to 10-mA using an improved DC high voltage GaAs photogun

    SciTech Connect

    J. Grames; M. Poelker; P. Adderley; J. Brittian; J. Clark; J. Hansknecht; D. Machie; M.L. Stutzman; K. Surles-Law

    2007-06-01

    This work extends past research at Jefferson Lab aimed at better appreciating the mechanisms that limit photocathode operational lifetime at high current (> 1 mA). Specifically, the performance of an improved 100 kV DC high voltage load locked photogun will be described. Although difficult to measure directly, we believe the new gun has better vacuum conditions compared to the original gun, as indicated by enhanced photocathode lifetimes exceeding 2000 C using a 1.55 mm diameter drive laser spot at the photocathode. In addition, the dependence of the lifetime on the laser spot size at the photocathode was measured and a charge density lifetime exceeding 10^6 C/cm^2 was measured with a 0.32 mm laser spot diameter.

  13. Evaluation of the Cell Voltage of Electrolytic HI Concentration for Thermochemical Water-Splitting Iodine-Sulfur Process

    SciTech Connect

    Tanaka, Nobuyuki; Yoshida, Mitsunori; Okuda, Hiroyuki; Sato, Hiroyuki; Kubo, Shinji; Onuki, Kaoru

    2007-07-01

    Breakdown of the cell voltage in the electro-dialysis process for concentrating HIx solution (HI-H{sub 2}O-I{sub 2} mixture) was preliminarily examined in an effort to clarify the optimal operation condition as well as to optimize the cell design for the application to the thermochemical water-splitting IS process for large-scale hydrogen production. Basic data such as electric resistance of HIx solution, overvoltage of the iodine-iodide ion redox reaction at graphite electrode, and the membrane voltage drop, were measured using HIx solution with composition of interest. Also, a methodology for estimating the cell voltage was discussed. The calculated cell voltage agreed well with the experimental one indicating the validity of the procedure adopted. (authors)

  14. Effects of surface adsorbed oxygen, applied voltage, and temperature on UV photoresponse of ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Zong, Xian-Li; Zhu, Rong

    2015-10-01

    The ultraviolet (UV) photoresponses of ZnO nanorods directly grown on and between two micro Au-electrodes by using electric-field-assisted wet chemical method are measured comprehensively under different conditions, including ambient environment, applied bias voltage, gate voltage and temperature. Experimental results indicate that the photoresponses of the ZnO nanorods can be modulated by surface oxygen adsorptions, applied voltages, as well as temperatures. A model taking into account both surface adsorbed oxygen and electron-hole activities inside ZnO nanorods is proposed. The enhancement effect of the bias voltage on photoresponse is also analyzed. Experimental results shows that the UV response time (to 63%) of ZnO nanorods in air and at 59 °C could be shortened from 34.8 s to 0.24 s with a bias of 4 V applied between anode and cathode. Project supported by the National Natural Science Foundation of China (Grant No. 91123017).

  15. I-V Characteristic for ZnO MSM Photodetector with Pd Contact Electrodes on PPC Plastic

    SciTech Connect

    Jandow, N. N.; Ibrahim, K.; Hassan, H. Abu

    2010-07-07

    ZnO thin film was deposited on polypropylene carbonate (PPC) plastic substrate by direct current (DC) sputtering. The measurements of the absorption spectrum and the photoluminescence of the film were carried out. ZnO Metal-Semiconductor-Metal (MSM) photodetector with palladium (Pd) contact electrodes was then fabricated. The structural and electrical properties of the detector were investigated using the current-voltage (I-V) measurements.

  16. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-01

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

  17. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma.

    PubMed

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-01

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas. PMID:23464206

  18. Pure ion current collection in ion sensitive probe measurement with a metal mesh guard electrode for evaluation of ion temperature in magnetized plasma

    SciTech Connect

    Hsieh, Tung-Yuan; Kawamori, Eiichirou; Nishida, Yasushi

    2013-02-15

    This paper presents a new design of ion sensitive probe (ISP) that enables collection of pure ion current for accurate measurement of the perpendicular ion temperature in magnetized plasmas. The new type of ISP resolves a longstanding issue widely observed in ISP type measurements, namely, that the current-voltage characteristic is smeared by an unexpected electron current in the standard ISP model. The new ISP is equipped with a fine scale metal mesh on the sensor entrance to prevent electrons from flowing to the sensor, a phenomenon considered to be caused by the space-charge effect. The new ISP successfully measured the ion temperature of electron cyclotron resonance plasmas.

  19. Absolute OH density measurements in an atmospheric pressure dc glow discharge in air with water electrode by broadband UV absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Xiong, Qing; Yang, Zhiqiang; Bruggeman, Peter J.

    2015-10-01

    Spatially resolved absolute OH radical density measurements are performed in an atmospheric pressure glow discharge generated in ambient air with water electrode by broadband UV absorption spectroscopy. The radial distributions of OH density and gas temperature are obtained for the positive column, anode and cathode regions both for water-cathode and water-anode discharges. It is found that for both polarities of the water electrode the radial profiles of the ground state OH density and gas temperature are significantly broader than the total discharge emission intensity and the emission intensity originating from OH(\\text{A}{}2{{\\text{ }?\\text{ }}+} ) only. Exceptional large OH densities exceeding 1023?m-3 are found. The OH kinetics are discussed in detail.

  20. Voltage Sensors Monitor Harmful Static

    NASA Technical Reports Server (NTRS)

    2009-01-01

    A tiny sensor, small enough to be worn on clothing, now monitors voltage changes near sensitive instruments after being created to alert Agency workers to dangerous static buildup near fuel operations and avionics. San Diego s Quasar Federal Systems received a Small Business Innovation Research (SBIR) contract from Kennedy Space Center to develop its remote voltage sensor (RVS), a dime-sized electrometer designed to measure triboelectric changes in the environment. One of the unique qualities of the RVS is that it can detect static at greater distances than previous devices, measuring voltage changes from a few centimeters to a few meters away, due to its much-improved sensitivity.

  1. Measurement and Calculation of Electrochemical Potentials in Hydrogenated High Temperature Water, including an Evaluation of the Yttria-Stabilized Zirconia/Iron-Iron Oxide (Fe/Fe3O4) Probe as Reference Electrode

    SciTech Connect

    Steven A. Attanasio; David S. Morton; Mark A. Ando

    2001-10-22

    The importance of knowing the electrochemical corrosion potential (ECP, also referred to as E{sub con}) of nickel-base alloys in hydrogenated water is related to the need to understand the effects of dissolved (i.e., aqueous) hydrogen concentration ([H{sub 2}]) on primary water stress corrosion cracking (PWSCC). Also, the use of a reference electrode (RE) can improve test quality by heightening the ability to detect instances of out-of-specification or unexpected chemistry. Three methods are used to measure and calculate the ECP of nickel-based alloys in hydrogenated water containing {approx} 1 to 150 scc/kg H{sub 2} (0.1 to 13.6 ppm H{sub 2}) at 260 to 360 C. The three methods are referred to as the specimen/component method, the platinum (Pt) method, and the yttria-stabilized zirconia/iron-iron oxide (YSZ/Fe-Fe{sub 3}O{sub 4}) RE method. The specimen/component method relies upon the assumption that the specimen or component behaves as a hydrogen electrode, and its E{sub corr} is calculated using the Nernst equation. The present work shows that this method is valid for aqueous H{sub 2} levels {ge} {approx} 5 to 10 scc/kg H{sub 2}. The Pt method uses a voltage measurement between the specimen or component and a Pt electrode, with the Pt assumed to behave as a hydrogen electrode; this method is valid as long as the aqueous H{sub 2}level is known. The YSZ/Fe-Fe{sub 3}O{sub 4}, which represents a relatively new approach for measuring E{sub corr} in this environment, can be used even if the aqueous H{sub 2} level is unknown. The electrochemical performance of the YSZ/Fe-Fe{sub 3}O{sub 4} probe supports its viability as a RE for use in high temperature hydrogenated water. Recent design modifications incorporating a teflon sealant have improved the durability of this RE (however, some of the REs do still fail prematurely due to water in-leakage). The Pt method is judged to represent the best overall approach, though there are cases where the other methods are superior. For example, the specimen/component method provides the simplest approach for calculating the E{sub corr} of plant components, and the YSZ/Fe-Fe{sub 3}O{sub 4} RE method provides the best approach if the H{sub 2} level is unknown, or in off-nominal chemistry conditions. The present paper describes the use of these methods to determine the ECP of a specimen or component versus the ECP of the nickel/nickel oxide (Ni/NiO) phase transition, which is important since prior work has shown that this parameter (ECP-ECP{sub Ni/NiO}) can be used to assess aqueous H{sub 2} effects on PWSCC.

  2. Characterization of plasma ion source utilizing anode spot with positively biased electrode for stable and high-current ion beam extraction

    SciTech Connect

    Park, Yeong-Shin; Lee, Yuna; Chung, Kyoung-Jae; Hwang, Y. S.

    2011-12-15

    The operating conditions of a rf plasma ion source utilizing a positively biased electrode have been investigated to develop a stably operating, high-current ion source. Ion beam characteristics such as currents and energies are measured and compared with bias currents by varying the bias voltages on the electrode immersed in the ambient rf plasma. Current-voltage curves of the bias electrode and photographs confirm that a small and dense plasma, so-called anode spot, is formed near an extraction aperture and plays a key role to enhance the performance of the plasma ion source. The ion beam currents from the anode spot are observed to be maximized at the optimum bias voltage near the knee of the characteristic current-voltage curve of the anode spot. Increased potential barrier to obstruct beam extraction is the reason for the reduction of the ion beam current in spite of the increased bias current indicating the density of the anode spot. The optimum bias voltage is measured to be lower at higher operating pressure, which is favorable for stable operation without severe sputtering damage on the electrode. The ion beam current can be further enhanced by increasing the power for the ambient plasma without increasing the bias voltage. In the same manner, noble gases with higher atomic number as a feedstock gas are preferable for extracting higher beam current more stably. Therefore, performance of the plasma ion source with a positively biased electrode can be enhanced by controlling the operating conditions of the anode spot in various manners.

  3. Breakdown and Partial Discharge Measurements of Some Commonly Used Dielectric Materials in Liquid Nitrogen for HTS Applications

    SciTech Connect

    James, David Randy; Sauers, Isidor; Ellis, Alvin R; Tuncer, Enis; Tekletsadik, Kasegn; Hazelton, Drew

    2007-01-01

    For high temperature superconducting (HTS) power applications it is necessary to improve the understanding of the dielectric properties of materials in a cryogenic environment. It is necessary to know the breakdown strength of materials and systems as a function of gap in order to scale to higher voltages. The partial discharge (PD) onset voltage for materials is also very important since the primary aging mechanism at cryogenic temperature is PD. Another important design characteristic is the surface flashover voltage of a material in liquid nitrogen as a function of gap. With these characteristics in mind, several generic materials were investigated under a variety of electrode and gap configurations. The impulse breakdown voltage and PD onset of three types of commercial polyetherimide, filled and unfilled, were measured at room temperature and 77 K. A modest increase in PD onset voltage was observed at the lower temperature. Breakdown voltages of fiberglass reinforced plastic (FRP) cylinders for two wall thicknesses were measured which showed a decrease in strength at the larger gap. Breakdown voltages for liquid nitrogen using a sphere-plane electrode geometry were measured. Also flashover voltages along a FRP plate immersed in liquid nitrogen were performed for sphere-plane and rod-plane electrodes at 1 bar pressure. It was found that the breakdown voltage increased only slightly with increasing gap lengths.

  4. Powder processing of hybrid titanium neural electrodes

    NASA Astrophysics Data System (ADS)

    Lopez, Jose Luis, Jr.

    A preliminary investigation into the powder production of a novel hybrid titanium neural electrode for EEG is presented. The rheological behavior of titanium powder suspensions using sodium alginate as a dispersant are examined for optimal slip casting conditions. Electrodes were slip cast and sintered at 950°C for 1 hr, 1000°C for 1, 3, and 6 hrs, and 1050°C for 1 hr. Residual porosities from sintering are characterized using Archimedes' technique and image analysis. The pore network is gel impregnated by submerging the electrodes in electrically conductive gel and placing them in a chamber under vacuum. Gel evaporation of the impregnated electrodes is examined. Electrodes are characterized in the dry and gelled states using impedance spectrometry and compared to a standard silver- silver chloride electrode. Power spectral densities for the sensors in the dry and gelled state are also compared. Residual porosities for the sintered specimens were between 50.59% and 44.81%. Gel evaporation tests show most of the impregnated gel evaporating within 20 min of exposure to atmospheric conditions with prolonged evaporation times for electrodes with higher impregnated gel mass. Impedance measurements of the produced electrodes indicate the low impedance of the hybrid electrodes are due to the increased contact area of the porous electrode. Power spectral densities of the titanium electrode behave similar to a standard silver-silver chloride electrode. Tests suggest the powder processed hybrid titanium electrode's performance is better than current dry contact electrodes and comparable to standard gelled silver-silver chloride electrodes.

  5. Production of high voltage by ion bombardment 

    E-print Network

    Phinney, Lucas Carter

    2003-01-01

    A beam of He+ ions was used to bombard a conductive target, allowing the target to build up a voltage. The voltage that built up on the target was measured by using a voltage divider circuit. The target was made out of niobium metal...

  6. Thrust measurements of a hollow-cathode discharge

    NASA Technical Reports Server (NTRS)

    Snyder, A.; Banks, B. A.

    1972-01-01

    Thrust measurements of a hollow cathode mercury discharge were made with a synthetic mica target on a torsion pendulum. Thrust measurements were made for various target angles, tip temperatures, flow rates, keeper discharge powers, and accelerator electrode voltages. The experimental thrust data are compared with theoretical values for the case where no discharge power was employed.

  7. Measurement of the internal stress and electric field in a resonating piezoelectric transformer for high-voltage applications using the electro-optic and photoelastic effects

    SciTech Connect

    VanGordon, James A.; Kovaleski, Scott D. Norgard, Peter; Gall, Brady B.; Dale, Gregory E.

    2014-02-15

    The high output voltages from piezoelectric transformers are currently being used to accelerate charged particle beams for x-ray and neutron production. Traditional methods of characterizing piezoelectric transformers (PTs) using electrical probes can decrease the voltage transformation ratio of the device due to the introduction of load impedances on the order of hundreds of kiloohms to hundreds of megaohms. Consequently, an optical diagnostic was developed that used the photoelastic and electro-optic effects present in piezoelectric materials that are transparent to a given optical wavelength to determine the internal stress and electric field. The combined effects of the piezoelectric, photoelastic, and electro-optic effects result in a time-dependent change the refractive indices of the material and produce an artificially induced, time-dependent birefringence in the piezoelectric material. This induced time-dependent birefringence results in a change in the relative phase difference between the ordinary and extraordinary wave components of a helium-neon laser beam. The change in phase difference between the wave components was measured using a set of linear polarizers. The measured change in phase difference was used to calculate the stress and electric field based on the nonlinear optical properties, the piezoelectric constitutive equations, and the boundary conditions of the PT. Maximum stresses of approximately 10 MPa and electric fields of as high as 6 kV/cm were measured with the optical diagnostic. Measured results were compared to results from both a simple one-dimensional (1D) model of the piezoelectric transformer and a three-dimensional (3D) finite element model. Measured stresses and electric fields along the length of an operating length-extensional PT for two different electrical loads were within at least 50 % of 3D finite element simulated results. Additionally, the 3D finite element results were more accurate than the results from the 1D model for a wider range of electrical load impedances under test.

  8. Cermet electrode

    DOEpatents

    Maskalick, Nicholas J. (Pittsburgh, PA)

    1988-08-30

    Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

  9. Method to detect the end-point for PCR DNA amplification using an ionically labeled probe and measuring impedance change

    DOEpatents

    Miles, Robin R. (Danville, CA); Belgrader, Phillip (Severna Park, MD); Fuller, Christopher D. (Oakland, CA)

    2007-01-02

    Impedance measurements are used to detect the end-point for PCR DNA amplification. A pair of spaced electrodes are located on a surface of a microfluidic channel and an AC or DC voltage is applied across the electrodes to produce an electric field. An ionically labeled probe will attach to a complementary DNA segment, and a polymerase enzyme will release the ionic label. This causes the conductivity of the solution in the area of the electrode to change. This change in conductivity is measured as a change in the impedance been the two electrodes.

  10. Investigation of an Aberrant Cell Voltage During the Filling of a Large Lithium Thionyl Chloride Cell

    NASA Technical Reports Server (NTRS)

    Thaller, Lawrence H.; Quinzio, Michael V.

    1997-01-01

    The investigation of an aberrant cell voltage during the filling of a large lithium thionyl chloride cell summary is at: an aberrant voltage trace was noted during the review of cell filling data; incident was traced to an interruption during filling; experimentation suggested oxidizable sites within the carbon electrode were responsible for the drop in voltage; the voltage anomaly could be reproduced by interrupting the filling of similar cells; and anomalous voltage dip was not due to a short.

  11. Dual-Electrode CMUT With Non-Uniform Membranes for High Electromechanical Coupling Coefficient and High Bandwidth Operation

    PubMed Central

    Guldiken, Rasim O.; Zahorian, Jaime; Yamaner, F. Y.; Degertekin, F. L.

    2010-01-01

    In this paper, we report measurement results on dual-electrode CMUT demonstrating electromechanical coupling coefficient (k2) of 0.82 at 90% of collapse voltage as well as 136% 3 dB one-way fractional bandwidth at the transducer surface around the design frequency of 8 MHz. These results are within 5% of the predictions of the finite element simulations. The large bandwidth is achieved mainly by utilizing a non-uniform membrane, introducing center mass to the design, whereas the dual-electrode structure provides high coupling coefficient in a large dc bias range without collapsing the membrane. In addition, the non-uniform membrane structure improves the transmit sensitivity of the dual-electrode CMUT by about 2dB as compared with a dual electrode CMUT with uniform membrane. PMID:19574135

  12. High voltage load resistor array

    DOEpatents

    Lehmann, Monty Ray (Smithfield, VA)

    2005-01-18

    A high voltage resistor comprising an array of a plurality of parallel electrically connected resistor elements each containing a resistive solution, attached at each end thereof to an end plate, and about the circumference of each of the end plates, a corona reduction ring. Each of the resistor elements comprises an insulating tube having an electrode inserted into each end thereof and held in position by one or more hose clamps about the outer periphery of the insulating tube. According to a preferred embodiment, the electrode is fabricated from stainless steel and has a mushroom shape at one end, that inserted into the tube, and a flat end for engagement with the end plates that provides connection of the resistor array and with a load.

  13. Comparison of Twitch Responses During Current- or Voltage-Controlled Transcutaneous Neuromuscular Electrical Stimulation.

    PubMed

    Vargas Luna, José Luis; Krenn, Matthias; Löfler, Stefan; Kern, Helmut; Cortés R, Jorge A; Mayr, Winfried

    2015-10-01

    Neuromuscular electrical stimulation (NMES) is an established method for functional restoration of muscle function, rehabilitation, and diagnostics. In this work, NMES was applied with surface electrodes placed on the anterior thigh to identify the main differences between current-controlled (CC) and voltage-controlled (VC) modes. Measurements of the evoked knee extension force and the myoelectric signal of quadriceps and hamstrings were taken during stimulation with different amplitudes, pulse widths, and stimulation techniques. The stimulation pulses were rectangular and symmetric biphasic for both stimulation modes. The electrode-tissue impedance influences the differences between CC and VC stimulation. The main difference is that for CC stimulation, variation of pulse width and amplitude influences the amount of nerve depolarization, whereas VC stimulation is only dependent on amplitude variations for pulse widths longer than 150??s. An important remark is that these findings are strongly dependent on the characteristics of the electrode-skin interface. In our case, we used large stimulation electrodes placed on the anterior thigh, which cause higher capacitive effects. The controllability, voltage compliance, and charge characteristics of each stimulation technique should be considered during the stimulators design. For applications that require the activation of a large amount of nerve fibers, VC is a more suitable option. In contrast, if the application requires a high controllability, then CC should be chosen prior to VC. PMID:26471138

  14. Photoelectrochemical electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Rembaum, A. (inventors)

    1983-01-01

    The surface of a moderate band gap semiconductor such as p-type molybdenum sulfide is modified to contain an adherent film of charge mediating ionene polymer containing an electroactive unit such as bipyridimium. Electron transport between the electrode and the mediator film is favorable and photocorrosion and recombination processes are suppressed. Incorporation of particles of catalyst such as platinum within the film provides a reduction in overvoltage. The polymer film is readily deposited on the electrode surface and can be rendered stable by ionic or addition crosslinking. Catalyst can be predispersed in the polymer film or a salt can be impregnated into the film and reduced therein.

  15. High Voltage TAL Erosion Characterization

    NASA Technical Reports Server (NTRS)

    Jacobson, David T.

    2003-01-01

    Extended operation of a D-80 anode layer thruster at high voltage was investigated. The thruster was operated for 1200 hours at 700 Volts and 4 Amperes. Laser profilometry was employed to quantify the erosion of the thruster's graphite guard rings and electrodes at 0, 300, 600, 900, and 1200 hours. Thruster performance and electrical characteristics were monitored over the duration of the investigation. The guard rings exhibited asymmetric erosion that was greatest in the region of the cathode. Erosion of the guard rings exposed the magnet poles between 600 to 900 hours of operation.

  16. Electrochemical Double-Layer Capacitors Using Carbon Nanotube Electrode Structures

    E-print Network

    Schindall, Joel E.

    The structure and behavior of the electrical double-layer capacitor (EDLC) are described. The use of activated carbon electrodes is discussed and the limitations on voltage and accessible surface area are presented. Metrics ...

  17. Noise characteristics of stainless-steel surface electrodes.

    PubMed

    Godin, D T; Parker, P A; Scott, R N

    1991-11-01

    Bioelectric events measured with surface electrodes are subject to noise components which may be significant in comparison with low-level biological signals such as evoked neuroelectric potentials, and myoelectric potentials. In an effort to better understand noise arising from these electrodes, electrode and measurement system noise is modelled. The effect of electrode surface area on electrode impedance and noise is studied using circular stainless-steel electrodes of varying diameters. The main contributions of the work are the development of a model for stainless-steel electrode noise as a function of electrode area, and demonstrating that, for the band-width of interest to evoked neuroelectric and myoelectric signals (8-10,000 Hz), the primary noise components are thermal and amplifier current generated. The magnitudes of both of these depend on the electrode impedance magnitude. Electrode impedance is shown to be a power function of both electrode diameter and frequency, consistent with a capacitive electrode model. PMID:1813753

  18. Development of Resistive Electrode Gas Electron Multiplier (RE-GEM)

    NASA Technical Reports Server (NTRS)

    Yoshikawa, A.; Tamagawa, T.; Iwahashi, T.; Asami, F.; Takeuchi, Y.; Hayato, A.; Hamagaki, H.; Gunji, T.; Akimoto, R.; Nukariya, A.; Hayashi, S.; Ueno, K.; Ochi, A.; Oliveria, R.

    2012-01-01

    We successfully produced Resistive-Electrode Gas Electron Multiplier (RE-GEM) which has resistive electrodes instead of the metal ones which are employed for the standard GEM foils. RE-GEM has a resistive electrode of 25 micron-thick and an insulator layer of 100 micron-thick. The hole structure of RE-GEM is a single conical with the wider and narrower hole diameters of 80 micron and 60 micron, respectively. A hole pitch of RE-GEM is 140 micron. We obtained the maximum gain of about 600 and the typical energy resolution of about 20% (FWHM) at an applied voltage between the resistive electrodes of 620 V, using a collimated 8 keV X-rays from a generator in a gas mixture of 70% Ar and 30% CO2 by volume at the atmospheric pressure. We measured the effective gain as a function of the electric field of the drift region and obtained the maximum gain at an drift field of 0.5 kV/cm.

  19. High Voltage Seismic Generator

    NASA Astrophysics Data System (ADS)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes constructed device very mobile. The project is still developing.

  20. Operational principle, testing, and applications of the AWID-flat jack for absolute stress determinations using voltage measurements

    NASA Astrophysics Data System (ADS)

    Kessels, W.

    1986-07-01

    Stress measurements can be performed with the, measuring principle for a flat jack discussed in this paper without any material parameters of the flat jack being of influence. This means that no calibration measurements are required by this flat jack for absolute measurements and there is no dependence on temperature. It is called “Absolut Widerstands Druckmesskissen” or short AWID-Flat Jack. Basis of evaluation is a change in the electrical resistivity of the flat jack, which is caused by two metal sheets separating from each other when inflated with hydraulic oil as soon as the external pressure is reached. Besides theoretical considerations concerning the mode of operation of the flat jack, this paper presents laboratory measurements performed in an autoclave as well as in a tube filled with salt grit under a uniaxial press. Changes of stress can be measured if the flat jack is cemented into a borehole under initial stress. The absolute stress of the bedrock can be measured after a certain time of adjustment in rock capable of creep (salt, clay, etc.). The advantages of the AWID measuring system are confirmed by in situ-measurements in a salt pillar loadable with variable pressure. In a temperature experiment at the Asse salt mine (Federal Republic of Germany) where the salt was heated up to 200°C, the advantages of the AWID measurement system were confirmed.

  1. Weld electrode cooling study

    NASA Astrophysics Data System (ADS)

    Masters, Robert C.; Simon, Daniel L.

    1999-03-01

    The U.S. auto/truck industry has been mandated by the Federal government to continuously improve their fleet average gas mileage, measured in miles per gallon. Several techniques are typically used to meet these mandates, one of which is to reduce the overall mass of cars and trucks. To help accomplish this goal, lighter weight sheet metal parts, with smaller weld flanges, have been designed and fabricated. This paper will examine the cooling characteristics of various water cooled weld electrodes and shanks used in resistance spot welding applications. The smaller weld flanges utilized in modern vehicle sheet metal fabrications have increased industry's interest in using one size of weld electrode (1/2 inch diameter) for certain spot welding operations. The welding community wants more data about the cooling characteristics of these 1/2 inch weld electrodes. To hep define the cooling characteristics, an infrared radiometer thermal vision system (TVS) was used to capture images (thermograms) of the heating and cooling cycles of several size combinations of weld electrodes under typical production conditions. Tests results will show why the open ended shanks are more suitable for cooling the weld electrode assembly then closed ended shanks.

  2. Method of improving fuel cell performance by removing at least one metal oxide contaminant from a fuel cell electrode

    DOEpatents

    Kim, Yu Seung (Los Alamos, NM); Choi, Jong-Ho (Los Alamos, NM); Zelenay, Piotr (Los Alamos, NM)

    2009-08-18

    A method of removing contaminants from a fuel cell catalyst electrode. The method includes providing a getter electrode and a fuel cell catalyst electrode having at least one contaminant to a bath and applying a voltage sufficient to drive the contaminant from the fuel cell catalyst electrode to the getter electrode. Methods of removing contaminants from a membrane electrode assembly of a fuel cell and of improving performance of a fuel cell are also provided.

  3. Widely applicable coinage metal window electrodes on flexible polyester substrates applied to organic photovoltaics.

    PubMed

    Stec, Helena M; Hatton, Ross A

    2012-11-01

    The fabrication, exceptional properties, and application of 8 nm thick Cu, Ag, Au, and Cu/Ag bilayer electrodes on flexible polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates is reported. These electrodes are fabricated using a solvent free process in which the plastic surface is chemically modified with a molecular monolayer of thiol and amine terminated alkylsilanes prior to metal deposition. The resulting electrodes have a sheet resistance of ?14 ? sq?¹, are exceptionally robust and can be rapidly thermally annealed at 200 °C to reduce their sheet resistance to ?9 ? sq?¹. Notably, annealing Au electrodes briefly at 200 °C causes the surface to revert almost entirely to the {111} face, rendering it ideal as a model electrode for fundamental science and practical application alike. The power conversion efficiency of 1 cm² organic photovoltaics (OPVs) employing 8 nm Ag and Au films as the hole-extracting window electrode exhibit performance comparable to those on indium-tin oxide, with the advantage that they are resistant to repeated bending through a small radius of curvature and are chemically well-defined. OPVs employing Cu and bilayer Cu:Ag electrodes exhibit inferior performance due to a lower open-circuit voltage and fill factor. Measurements of the interfacial energetics made using the Kelvin probe technique provide insight into the physical reason for this difference. The results show how coinage metal electrodes offer a viable alternative to ITO on flexible substrates for OPVs and highlight the challenges associated with the use of Cu as an electrode material in this context. PMID:23127805

  4. [Development of residual voltage testing equipment].

    PubMed

    Zeng, Xiaohui; Wu, Mingjun; Cao, Li; He, Jinyi; Deng, Zhensheng

    2014-07-01

    For the existing measurement methods of residual voltage which can't turn the power off at peak voltage exactly and simultaneously display waveforms, a new residual voltage detection method is put forward in this paper. First, the zero point of the power supply is detected with zero cross detection circuit and is inputted to a single-chip microcomputer in the form of pulse signal. Secend, when the zero point delays to the peak voltage, the single-chip microcomputer sends control signal to power off the relay. At last, the waveform of the residual voltage is displayed on a principal computer or oscilloscope. The experimental results show that the device designed in this paper can turn the power off at peak voltage and is able to accurately display the voltage waveform immediately after power off and the standard deviation of the residual voltage is less than 0.2 V at exactly one second and later. PMID:25330605

  5. Biased Electrodes for SOL Control in NSTX

    SciTech Connect

    Zweben, S. J.; Maqueda, R. J.; Roqemore, A. L.; Bush, C. E.; Kaita, R.; Marsala, R. J.; Raitses, Y.; Cohen, R. H.; Ryutov, D. D.

    2009-01-01

    Small electrodes were installed in the outer-midplane edge of NSTX to attempt to control the local width of the scrape-off layer (SOL) by creating an outward E(pol)xB flow. When the applied voltage between electrodes was 90 V, the density between these electrodes increased by a factor of 3-10 over a radial width of similar to 4 cm. Thus a local control of the SOL plasma density was obtained. (C) 2009 Elsevier B.V. All rights reserved.

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

    PubMed Central

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

    2010-01-01

    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

  7. The aluminum electrode in AlCl3-alkali-halide melts

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Giner, J.

    1972-01-01

    Passivation phenomena were observed upon cathodic and anodic polarization of the Al electrode in AlCl3-KCl-NaCl melts between 100 and 160 C. They are caused by formation of a solid salt layer at the electrode surface resulting from concentration changes upon current flow. The anodic limiting currents increased with temperature and with decreasing AlCl3 content of the melt. Current voltage curves obtained on a rotating aluminum disk showed a linear relationship between the anodic limiting current and 1/sq root of 2 pi (rps). Upon cathodic polarization dentrite formation occurs at the Al electrode. The activation overvoltage in AlCl3-KCl-NaCl (57.5-12.5-20 mol%) was determined by galvanostatic current step methods. An apparent exchange current density of 270 mA/cm2 at 130 C and a double layer capacity of 40 plus or minus 10 microfarad/cm2 were measured.

  8. The aluminum electrode in AlCl3-alkali-halide melts.

    NASA Technical Reports Server (NTRS)

    Holleck, G. L.; Giner, J.

    1972-01-01

    Passivation phenomena have been observed upon cathodic and anodic polarization of the Al electrode in AlCl3-KCl-NaCl melts between 100 and 160 C. They are caused by formation of a solid salt layer at the electrode surface resulting from concentration changes upon current flow. The anodic limiting currents increased with temperature and with decreasing AlCl3 content of the melt. Current voltage curves obtained on a rotating aluminum disk showed a linear relationship between the anodic limiting current and omega to the minus 1/2 power. Upon cathodic polarization, dendrite formation occurs at the Al electrode. The activation overvoltage in AlCl3-KCl-NaCl was determined by galvanostatic current step methods. An apparent exchange current density of 270 mA/sq cm at 130 C and a double layer capacity of 40 plus or minus 10 microfarad/sq cm were measured.

  9. Application of stochastic Galerkin FEM to the complete electrode model of electrical impedance tomography

    SciTech Connect

    Leinonen, Matti Hakula, Harri Hyvönen, Nuutti

    2014-07-15

    The aim of electrical impedance tomography is to determine the internal conductivity distribution of some physical body from boundary measurements of current and voltage. The most accurate forward model for impedance tomography is the complete electrode model, which consists of the conductivity equation coupled with boundary conditions that take into account the electrode shapes and the contact resistances at the corresponding interfaces. If the reconstruction task of impedance tomography is recast as a Bayesian inference problem, it is essential to be able to solve the complete electrode model forward problem with the conductivity and the contact resistances treated as a random field and random variables, respectively. In this work, we apply a stochastic Galerkin finite element method to the ensuing elliptic stochastic boundary value problem and compare the results with Monte Carlo simulations.

  10. Performance of 3rd electrode cells in OAO.

    NASA Technical Reports Server (NTRS)

    Ford, F. E.

    1972-01-01

    The OAO 2 satellite employed nickel-cadmium batteries with auxiliary (signal) electrodes for overcharge control. During the early life of the satellite, these third-electrode signals provided an orbit-by-orbit indication of the overcharge received by the batteries. By ground command, the battery charger was adjusted on a need basis to provide optimum recharge conditions as indicated by the third-electrode signals during all phases of spacecraft operation and orientation. After more than two years, an unusual degradation in third-electrode signals was observed, providing the first indication of battery degradation. The present paper examines the operation of the battery system and analyzes the battery degradation mechanism. The abnormal performance of the third electrode is related to cell-voltage divergence during periods of overcharge. Cells that had a higher cell voltage showed signs (third-electrode degradation) of small amounts of hydrogen gas generation.

  11. Understanding S-shaped current-voltage characteristics of organic solar cells: Direct measurement of potential distributions by scanning Kelvin probe

    SciTech Connect

    Saive, Rebecca Kowalsky, Wolfgang; Institut für Hochfrequenztechnik, TU Braunschweig, 38106 Braunschweig; Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg ; Mueller, Christian; Kirchhoff-Institute for Physics, Heidelberg University, 69120 Heidelberg ; Schinke, Janusz; Lovrincic, Robert; Institut für Hochfrequenztechnik, TU Braunschweig, 38106 Braunschweig

    2013-12-09

    We present a comparison of the potential distribution along the cross section of bilayer poly(3-hexylthiophene)/1-(3-methoxycarbonyl)propyl-1-phenyl[6,6]C61 (P3HT/PCBM) solar cells, which show normal and anomalous, S-shaped current-voltage (IV) characteristics. We expose the cross sections of the devices with a focussed ion beam and measure them with scanning Kelvin probe microscopy. We find that in the case of S-shaped IV-characteristics, there is a huge potential drop at the PCBM/Al top contact, which does not occur in solar cells with normal IV-characteristics. This behavior confirms the assumption that S-shaped curves are caused by hindered charge transport at interfaces.

  12. Pacing threshold trends and variability in modern tined leads assessed using high resolution automatic measurements: conversion of pulse width into voltage thresholds.

    PubMed

    Danilovic, D; Ohm, O J

    1999-04-01

    With the aid of an algorithm for automatic pacing threshold (T) measurement in the atrium and ventricle, downloadable into implanted Thera pacemakers (Medtronic Inc.), we studied T evolution during lead maturation, T variation during activities of daily living, and various types of beat-to-beat T variations in three tined bipolar leads: 5.6-mm2 steroid-eluting (Medtronic Inc. models 4524 atrial-J [n = 8] and 4024 ventricular [n = 8]), 1.2-mm2 steroid-eluting (Medtronic Inc. models 5534 atrial-J [n = 9] and 5034 ventricular [n = 9]), and 8-mm2 without steroid (Intermedics models 432-04 atrial-J [n = 7] and 430-10 ventricular [n = 7]). The leads were implanted in 24 consecutive patients with intact AV conduction (required by the algorithm) and followed for up to 13-25 months after implantation. Since the algorithm determined pulse width Ts at different amplitudes that, depending upon T level, could range from 0.5 to 5.0 V, we invented a methodology for conversion of pulse width Ts into voltage Ts at 0.5 ms, to pool and present T data on a universal scale. Frequent, high resolution T measurements revealed details on the lead maturation process that we divided into three stages: initial T subsiding, first wave of T peaking, and a new, quicker or slower, T rise. Although there were notable differences in duration and magnitude of T peaking on the individual basis, differences between the three lead types and between the atrium and ventricle were demonstrable. The 1.2-mm2 leads exhibited less T peaking than their predecessors 5.6-mm2 leads and excellent positional stability, whereas 8-mm2 leads demonstrated the most intensive T peaking and highest mean chronic T values. T changes during activities of daily living showed some tendencies-higher T during night and lower T during exercise--yet with a number of exceptions. The overall magnitude of daily T fluctuations was < 0.2 V in all but one lead, and 50% daily voltage safety margin would be sufficient. A 100% voltage safety margin may be inadequate for a 1-year period during the chronic phase (after 6 months of implantation). A scheme for calculation of pulse width safety margins equivalent to voltage safety margins is given. Some leads can exhibit very large beat-to-beat T variations before, during, and after T peaking, and prospective algorithms for automatic T measurement should verify T values through more than 1-2 captured beats to obviate a great underestimation of the T providing consistent capture. T dependence upon pacing rate was negligible. Consistent-capture hysteresis may, in conjunction with lead instability, be as much as 0.25 V. Therefore, it is better to use an incremental approach from below to T level during automatic T measurements. PMID:10234710

  13. Electro-optic device with gap-coupled electrode

    DOEpatents

    Deri, Robert J.; Rhodes, Mark A.; Bayramian, Andrew J.; Caird, John A.; Henesian, Mark A.; Ebbers, Christopher A.

    2013-08-20

    An electro-optic device includes an electro-optic crystal having a predetermined thickness, a first face and a second face. The electro-optic device also includes a first electrode substrate disposed opposing the first face. The first electrode substrate includes a first substrate material having a first thickness and a first electrode coating coupled to the first substrate material. The electro-optic device further includes a second electrode substrate disposed opposing the second face. The second electrode substrate includes a second substrate material having a second thickness and a second electrode coating coupled to the second substrate material. The electro-optic device additionally includes a voltage source electrically coupled to the first electrode coating and the second electrode coating.

  14. Control of electrode depth in electroslag remelting

    DOEpatents

    Melgaard, David K. (Albuquerque, NM); Shelmidine, Gregory J. (Tijeras, NM); Damkroger, Brian K. (Albuquerque, NM)

    2002-01-01

    A method of and apparatus for controlling an electroslag remelting furnace by driving the electrode at a nominal speed based upon melting rate and geometry while making minor proportional adjustments based on a measured metric of the electrode immersion depth. Electrode drive speed is increased if a measured metric of electrode immersion depth differs from a set point by a predetermined amount, indicating that the tip is too close to the surface of a slag pool. Impedance spikes are monitored to adjust the set point for the metric of electrode immersion depth based upon one or more properties of the impedance spikes.

  15. Surface potential measurement of fullerene derivative/copper phthalocyanine on indium tin oxide electrode by Kelvin probe force microscopy

    NASA Astrophysics Data System (ADS)

    Satoh, Nobuo; Yamaki, Michio; Noda, Kei; Katori, Shigetaka; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2015-08-01

    We have investigated the organic semiconductor thin films deposited by vacuum evaporation deposition using intersecting metal shadow masks on indium tin oxide (ITO) electrode/glass substrates to simulate organic solar cells by simultaneous observation with dynamic force microscopy (DFM)/Kelvin-probe force microscopy (KFM). The energy band diagram was depicted by simultaneously obtaining topographic and surface potential images of the same area using DFM/KFM. We considered the charge behavior at the interface having band bending in the phenyl-C61-butyric acid methyl ester (PCBM) film.

  16. Electrode structures

    SciTech Connect

    Brennan, M.P.

    1981-01-06

    In a sodium sulphur cell, a cathode electrode of annular form comprising a plurality of segments, each of trapezoidal form in cross-section and joined by webs along a longer edge of each segment so that the assembly is foldable to form a substantially annular structure. This electrode may be made by compressing a blanket or sheet of carbon or graphite felt or fibres in a heated mould, which is shaped to produce the segments joined by thin webs, the material being impregnated with sulphur or sodium polysulphide before or after insertion in the mould, and the material being cooled before removal from the mould. Alternatively, the segments may be formed from the blanket or sheet by using shaped rolls, the material being cooled, E.G. By water or air, as it leaves the rolls.

  17. Preamplifiers for non-contact capacitive biopotential measurements*

    PubMed Central

    Peng, GuoChen; Ignjatovic, Zeljko; Bocko, Mark F.

    2014-01-01

    Non-contact biopotential sensing is an attractive measurement strategy for a number of health monitoring applications, primarily the ECG and the EEG. In all such applications a key technical challenge is the design of a low-noise trans-impedance preamplifier for the typically low-capacitance, high source impedance sensing electrodes. In this paper, we compare voltage and charge amplifier designs in terms of their common mode rejection ratio, noise performance, and frequency response. Both amplifier types employ the same operational-transconductance amplifier (OTA), which was fabricated in a 0.35um CMOS process. The results show that a charge amplifier configuration has advantages for small electrode-to-subject coupling capacitance values (less than 10 pF - typical of noncontact electrodes) and that the voltage amplifier configuration has advantages for electrode capacitances above 10 pF. PMID:24109979

  18. Determination of the cathode and anode voltage drops in high power low-pressure amalgam lamps

    SciTech Connect

    Vasilyak, L. M.; Vasiliev, A. I. Kostyuchenko, S. V.; Sokolov, D. V.; Startsev, A. Yu.; Kudryavtsev, N. N.

    2011-12-15

    For the first time, cathode and anode drops of powerful low-pressure amalgam lamps were measured. The lamp discharge current is 3.2 A, discharge current frequency is 43 kHz, linear electric power is 2.4 W/cm. The method of determination of a cathode drop is based on the change of a lamp operating voltage at variation of the electrode filament current at constant discharge current. The total (cathode plus anode) drop of voltage was measured by other, independent ways. The maximum cathode fall is 10.8 V; the anode fall corresponding to the maximal cathode fall is 2.4 V. It is shown that in powerful low pressure amalgam lamps the anode fall makes a considerable contribution (in certain cases, the basic one) to heating of electrodes. Therefore, the anode fall cannot be neglected, at design an electrode and ballast of amalgam lamps with operating discharge current frequency of tens of kHz.

  19. Methods and apparatus for measurement of the resistivity of geological formations from within cased wells in presence of acoustic and magnetic energy sources

    DOEpatents

    Vail, W.B. III.

    1991-08-27

    Methods and apparatus are provided for measuring the acoustically modulated electronic properties of geological formations and cement layers adjacent to cased boreholes. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. Voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the leakage current conducted into formation in the vicinity of those electrodes. Simultaneously subjecting the casing and formation to an acoustic source acoustically modulates the leakage current measured thereby providing a measure of the acoustically modulated electronic properties of the adjacent formation. Similarly, methods and apparatus are also described which measure the leakage current into formation while simultaneously subjecting the casing to an applied magnetic field which therefore allows measurement of the magnetically modulated electronic properties of the casing and the adjacent formation. 9 figures.

  20. Methods and apparatus for measurement of the resistivity of geological formations from within cased wells in presence of acoustic and magnetic energy sources

    DOEpatents

    Vail, III, William B. (Bothell, WA)

    1991-01-01

    Methods and apparatus are provided for measuring the acoustically modulated electronic properties of geological formations and cement layers adjacent to cased boreholes. Current is passed from an electrode in electrical contact with the interior of the borehole casing to an electrode on the surface of the earth. Voltage measuring electrodes in electrical contact with the interior of the casing measure the voltage at various points thereon. The voltage differences between discrete pairs of the voltage measuring electrodes provide a measurement of the leakage current conducted into formation in the vicinity of those electrodes. Simultaneously subjecting the casing and formation to an acoustic source acoustically modulates the leakage current measured thereby providing a measure of the acoustically modulated electronic properties of the adjacent formation. Similarly, methods and apparatus are also described which measure the leakage current into formation while simultaneously subjecting the casing to an applied magnetic field which therefore allows measurement of the magnetically modulated electronic properties of the casing and the adjacent formation.

  1. A voltmeter for remotely sensing high voltages

    NASA Astrophysics Data System (ADS)

    Greene, H. W.; Holder, J. D.; Roberts, T. G.

    1984-03-01

    A passive voltmeter that measures pulses of high voltage by periodically discharging a condensor through a spark gap is presented. The frequency at which the spark gap breaks down is a function of the voltage being measured and is detected and displayed in volts. Radioactive material within the chamber is used to insure a constant breakdown voltage by supplying the necessary free electrons. This insures constant breakdown time for the arc with minimum jitter.

  2. Electrokinetic particle-electrode interactions at high frequencies

    NASA Astrophysics Data System (ADS)

    Yariv, Ehud; Schnitzer, Ory

    2013-01-01

    We provide a macroscale description of electrokinetic particle-electrode interactions at high frequencies, where chemical reactions at the electrodes are negligible. Using a thin-double-layer approximation, our starting point is the set of macroscale equations governing the “bounded” configuration comprising of a particle suspended between two electrodes, wherein the electrodes are governed by a capacitive charging condition and the imposed voltage is expressed as an integral constraint. In the large-cell limit the bounded model is transformed into an effectively equivalent “unbounded” model describing the interaction between the particle and a single electrode, where the imposed-voltage condition is manifested in a uniform field at infinity together with a Robin-type condition applying at the electrode. This condition, together with the standard no-flux condition applying at the particle surface, leads to a linear problem governing the electric potential in the fluid domain in which the dimensionless frequency ? of the applied voltage appears as a governing parameter. In the high-frequency limit ??1 the flow is dominated by electro-osmotic slip at the particle surface, the contribution of electrode electro-osmosis being O(?-2) small. That simplification allows for a convenient analytical investigation of the prevailing case where the clearance between the particle and the adjacent electrode is small. Use of tangent-sphere coordinates allows to calculate the electric and flows fields as integral Hankel transforms. At large distances from the particle, along the electrode, both fields decay with the fourth power of distance.

  3. A Matter of Quantum Voltages

    SciTech Connect

    Sellner, Bernhard; Kathmann, Shawn M.

    2014-11-14

    Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. Electron holography is able to measure the variation of voltages in matter and modern supercomputers allow the calculation of quantum voltages with practically unlimited spatial and temporal resolution of bulk systems. Of particular interest is the Mean Inner Potential (Vo) - the spatial average of these voltages. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of Vo for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Furthermore, we predict Vo as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences & Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle. This research used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

  4. A study on measurement of the surface charge accumulation using anodic aluminum oxide template

    NASA Astrophysics Data System (ADS)

    Oh, Seung-Ju; Lee, Hyo-Chang; Moon, Jun-Hyeon; Chung*, Chin-Wook; Kwon, Soon-Ho; Lee, Jung-Joong; Koo, Il-Gyo; Lee, Soo-Jin; Seong, Kyo-Seong; Plasma Surface Engineering Lab Collaboration; Semes Collaboration

    2013-09-01

    As the critical dimension of the nano-device shrinks, an undesired etch profile resulting from the local electric field by the surface charge accumulation is made on the plasma processing. To understand and monitor the surface charge accumulation, the measurement of the voltage difference between top electrode and bottom electrode on the anodic aluminum oxide (AAO) which has high aspect structure is performed in inductively coupled plasma. The voltage difference is changed with external discharge conditions, such as gas pressure, input power, and gas species, and the result is analyzed with the measured plasma parameters. This work was supported by SEMES cooperative research project.

  5. Development of an in situ calibration method for current-to-voltage converters for high-accuracy SI-traceable low dc current measurements

    NASA Astrophysics Data System (ADS)

    Eppeldauer, George P.; Yoon, Howard W.; Jarrett, Dean G.; Larason, Thomas C.

    2013-10-01

    For photocurrent measurements with low uncertainties, wide dynamic range reference current-to-voltage converters and a new converter calibration method have been developed at the National Institute of Standards and Technology (NIST). The high-feedback resistors of a reference converter were in situ calibrated on a high-resistivity, printed circuit board placed in an electrically shielded box electrically isolated from the operational amplifier using jumpers. The feedback resistors, prior to their installation, were characterized, selected and heat treated. The circuit board was cleaned with solvents, and the in situ resistors were calibrated using measurement systems for 10 k? to 10 G? standard resistors. We demonstrate that dc currents from 1 nA to 100 µA can be measured with uncertainties of 55 × 10-6 (k = 2) or lower, which are lower in uncertainties than any commercial device by factors of 10 to 30 at the same current setting. The internal (NIST) validations of the reference converter are described.

  6. High surface area electrodes in ionic polymer transducers: Numerical and experimental investigations of the electro-chemical behavior

    NASA Astrophysics Data System (ADS)

    Akle, Barbar J.; Habchi, Wassim; Wallmersperger, Thomas; Akle, Etienne J.; Leo, Donald J.

    2011-04-01

    Ionomeric polymer transducer (IPT) is an electroactive polymer that has received considerable attention due to its ability to generate large bending strain (>5%) and moderate stress at low applied voltages (±2 V). Ionic polymer transducers consist of an ionomer, usually Nafion, sandwiched between two electrically conductive electrodes. A novel fabrication technique denoted as the direct assembly process (DAP) enabled controlled electrode architecture in ionic polymer transducers. A DAP built transducer consists of two high surface area electrodes made of electrically conducting particles uniformly distributed in an ionomer matrix sandwiching an ionomer membrane. The purpose of this paper is to investigate and simulate the effect of these high surface area particles on the electro-chemical response of an IPT. Theoretical investigations as well as experimental verifications are performed. The model used consists of a convection-diffusion equation describing the chemical field as well as a Poisson equation describing the electrical field. The two-dimensional model incorporates highly conductive particles randomly distributed in the electrode area. Traditionally, these kinds of electrodes were simulated with boundary conditions representing flat electrodes with a large dielectric permittivity at the polymer boundary. This model enables the design of electrodes with complicated geometrical patterns. In the experimental section, several transducers are fabricated using the DAP process on Nafion 117 membranes. The architecture of the high surface area electrodes in these samples is varied. The concentration of the high surface area RuO2 particles is varied from 30 vol% up to 60 vol% at a fixed thickness of 30 ?m, while the overall thickness of the electrode is varied from 10 ?m up to 40 ?m at a fixed concentration of 45%. The flux and charge accumulation in the materials are measured experimentally and compared to the results of the numerical simulations. Trends of the experimental and numerical investigations are in agreement, while the computational capacity is limiting the ability to add sufficient amount of metal particle to the electrode in order to match the magnitudes.

  7. Long Life Nickel Electrodes for Nickel-Hydrogen Cells: Fiber Substrates Nickel Electrodes

    NASA Technical Reports Server (NTRS)

    Rogers, Howard H.

    2000-01-01

    Samples of nickel fiber mat electrodes were investigated over a wide range of fiber diameters, electrode thickness, porosity and active material loading levels. Thickness' were 0.040, 0.060 and 0.080 inches for the plaque: fiber diameters were primarily 2, 4, and 8 micron and porosity was 85, 90, and 95%. Capacities of 3.5 in. diameter electrodes were determined in the flooded condition with both 26 and 31% potassium hydroxide solution. These capacity tests indicated that the highest capacities per unit weight were obtained at the 90% porosity level with a 4 micron diameter fiber plaque. It appeared that the thinner electrodes had somewhat better performance, consistent with sintered electrode history. Limited testing with two-positive-electrode boiler plate cells was also carried out. Considerable difficulty with constructing the cells was encountered with short circuits the major problem. Nevertheless, four cells were tested. The cell with 95% porosity electrodes failed during conditioning cycling due to high voltage during charge. Discharge showed that this cell had lost nearly all of its capacity. The other three cells after 20 conditioning cycles showed capacities consistent with the flooded capacities of the electrodes. Positive electrodes made from fiber substrates may well show a weight advantage of standard sintered electrodes, but need considerably more work to prove this statement. A major problem to be investigated is the lower strength of the substrate compared to standard sintered electrodes. Problems with welding of leads were significant and implications that the electrodes would expand more than sintered electrodes need to be investigated. Loading levels were lower than had been expected based on sintered electrode experiences and the lower loading led to lower capacity values. However, lower loading causes less expansion and contraction during cycling so that stress on the substrate is reduced.

  8. Surface potential measurement of fullerene/copper phthalocyanine films on indium tin oxide electrode by Kelvin probe force microscopy

    NASA Astrophysics Data System (ADS)

    Satoh, Nobuo; Katori, Shigetaka; Kobayashi, Kei; Matsushige, Kazumi; Yamada, Hirofumi

    2014-01-01

    Various organic semiconductor thin films were deposited on an indium tin oxide (ITO) electrode/glass substrate to simulate organic solar cells. The electrical properties at the organic/inorganic and organic/organic interfaces were evaluated by dynamic-mode atomic force microscopy (DFM) together with Kelvin probe force microscopy (KFM). By employing the frequency modulation (FM) method, the DFM/KFM system allows for not only consistent imaging over a wide scanning area, but also highly sensitive detection of the surface potential. The charge carrier behavior at the interface was clarified by simultaneously obtaining topographic and surface potential images of the same area using DFM/KFM and depicting the energy band diagram with band bending in the fullerene (C60) film.

  9. Dry EEG Electrodes

    PubMed Central

    Lopez-Gordo, M. A.; Sanchez-Morillo, D.; Valle, F. Pelayo

    2014-01-01

    Electroencephalography (EEG) emerged in the second decade of the 20th century as a technique for recording the neurophysiological response. Since then, there has been little variation in the physical principles that sustain the signal acquisition probes, otherwise called electrodes. Currently, new advances in technology have brought new unexpected fields of applications apart from the clinical, for which new aspects such as usability and gel-free operation are first order priorities. Thanks to new advances in materials and integrated electronic systems technologies, a new generation of dry electrodes has been developed to fulfill the need. In this manuscript, we review current approaches to develop dry EEG electrodes for clinical and other applications, including information about measurement methods and evaluation reports. We conclude that, although a broad and non-homogeneous diversity of approaches has been evaluated without a consensus in procedures and methodology, their performances are not far from those obtained with wet electrodes, which are considered the gold standard, thus enabling the former to be a useful tool in a variety of novel applications. PMID:25046013

  10. Characterization of a radio frequency hollow electrode discharge at low gas pressures

    NASA Astrophysics Data System (ADS)

    Ahadi, Amir Mohammad; Trottenberg, Thomas; Rehders, Stefan; Strunskus, Thomas; Kersten, Holger; Faupel, Franz

    2015-08-01

    A radio frequency (RF) hollow discharge configuration is presented, which makes use of a combination of RF plasma generation and the hollow cathode effect. The system was especially designed for the treatment of nanoparticles, plasma polymerization, and nanocomposite fabrication. The process gas streams through the plasma in the inner of the cylindrical electrode system. In the here presented measurements, pure argon and argon with oxygen admixtures are exemplarily used. The discharge is characterized by probe measurements in the effluent, electrical measurements of the discharge parameters, and visual observations of the plasma glow. It is found that the RF fluctuations of the plasma potential are weak. The plasma potential resembles the one of a DC hollow cathode discharge, the RF hollow electrode acts as a cathode due to the self-bias, and a high voltage sheath forms in its inner cylinder.

  11. Thin film colossal dielectric constant oxide La{sub 2-x}Sr{sub x}NiO{sub 4}: Synthesis, dielectric relaxation measurements, and electrode effects

    SciTech Connect

    Podpirka, Adrian; Ramanathan, Shriram

    2011-01-01

    We have successfully synthesized the colossal dielectric constant oxide La{sub 2-x}Sr{sub x}NiO{sub 4} in thin film form by reactive cosputtering from metallic targets and careful annealing protocols. Composition and phase purity was determined through energy dispersive spectra and x-ray diffraction, respectively. The dielectric constant exceeds values of over 20 000 up to 1 kHz and the activation energy for the frequency-independent conductivity plateau was extracted to be approximately 155 meV from 300 to 473 K, both in agreement with measurements conducted on bulk single crystals. However, unlike in single crystals, we observe early onset of relaxation in thin films indicating the crucial role of grain boundaries in influencing the dielectric response. ac conductivity at varying temperatures is analyzed within the framework of the universal dielectric law leading to an exponent of approximately 0.3, dependent on the electrode material. Impedance spectroscopy with electrodes of different work function (Pt, Pd, and Ag) was further carried out as a function of temperature and applied bias to provide mechanistic insights into the nature of the dielectric response.

  12. Spectroscopic measurements of the electron number density, electron temperature and OH(A) rotational distribution in a liquid electrode dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Krähling, Tobias; Geisler, Sebastian; Okruss, Michael; Florek, Stefan; Franzke, Joachim

    2015-12-01

    The electron temperature and number density as well as the OH(A) rotational distribution of a discharge with flowing liquid electrode and dielectric barrier coupling (a liquid electrode dielectric barrier discharge, LE-DBD) were investigated by means of optical emission spectroscopy. By using the Stark broadening of three Strontium lines, the electron number density Ne and the lower bound of the electron temperature Te can be simultaneously measured. The values obtained were Ne = (0.8 - 1.6) × 1016 cm- 3 and Te > 1.1 eV, respectively. The OH(A) rotational distribution deviates from equilibrium and can be described by a superposition of two Boltzmann distributions with T1 = (3230 ± 90) K for K ' ? 15 and T2 = (7300 ± 300) K for K ' ? 16. Consideration of the formation mechanisms of OH(A) and reaction rates suggests that the dissociative recombination of H2O+ and H3O+ is responsible for the higher rotational state distribution, where these ions can only be produced in the LE-DBD through an electrospray-like process.

  13. Using in-process measurements of open-gate structures to evaluate threshold voltage of normally-off GaN-based high electron mobility transistors

    NASA Astrophysics Data System (ADS)

    Hou, Bin; Ma, Xiao-Hua; Chen, Wei-Wei; Zhu, Jie-Jie; Zhao, Sheng-Lei; Chen, Yong-He; Xie, Yong; Zhang, Jin-Cheng; Hao, Yue

    2015-10-01

    The parameters of open-gate structures treated with different etching time were monitored during the gate recess process, and their impacts on the threshold voltage (Vth) of final fabricated AlGaN/GaN high electron mobility transistors (HEMTs) based on open-gate structures were discussed in this paper. It is found that Vth can exceed 0 V when channel resistance in the recessed region (Ron-open) increases over ˜275 ? mm, maximum current (IDmax) decreases below ˜29 mA/mm, or recessed barrier thickness (tRB) is below ˜7.5 nm. In addition, tRB obtained by atomic force microscopy measurements and C-V measurements are also compared. Finally, theoretical common criteria based on the experimental results of this work for tRB and Ron-open were established to evaluate the Vth of a regular normally-off AlGaN/GaN HEMTs. The results indicate that these parameters of open-gate structure can be utilized to achieve normally-off HEMTs with controllable Vth.

  14. Determination of active doping in highly resistive boron doped silicon nanocrystals embedded in SiO2 by capacitance voltage measurement on inverted metal oxide semiconductor structure

    NASA Astrophysics Data System (ADS)

    Zhang, Tian; Puthen-Veettil, Binesh; Wu, Lingfeng; Jia, Xuguang; Lin, Ziyun; Yang, Terry Chien-Jen; Conibeer, Gavin; Perez-Wurfl, Ivan

    2015-10-01

    We investigate the Capacitance-Voltage (CV) measurement to study the electrically active boron doping in Si nanocrystals (ncSi) embedded in SiO2. The ncSi thin films with high resistivity (200-400 ? cm) can be measured by using an inverted metal oxide semiconductor (MOS) structure (Al/ncSi (B)/SiO2/Si). This device structure eliminates the complications from the effects of lateral current flow and the high sheet resistance in standard lateral MOS structures. The characteristic MOS CV curves observed are consistent with the effective p-type doping. The CV modeling method is presented and used to evaluate the electrically active doping concentration. We find that the highly boron doped ncSi films have electrically active doping of 1018-1019 cm-3 despite their high resistivity. The saturation of doping at about 1.4 × 1019 cm-3 and the low doping efficiency less than 5% are observed and discussed. The calculated effective mobility is in the order of 10-3 cm2/V s, indicating strong impurity/defect scattering effect that hinders carriers transport.

  15. Zero-dipole molecular organic cations in mixed organic-inorganic halide perovskites: possible chemical solution for the reported anomalous hysteresis in the current-voltage curve measurements.

    PubMed

    Giorgi, Giacomo; Yamashita, Koichi

    2015-11-01

    Starting from a brief description of the main architectures characterizing the novel solar technology of perovskite-based solar cells, we focus our attention on the anomalous hysteresis experimentally found to affect the measurement of the current-voltage curve of such devices. This detrimental effect, associated with slow dynamic reorganization processes, depends on several parameters; among them, the scan rate of the measurements, the architecture of the cell, and the perovskite deposition rate are crucial. Even if a conclusive explanation of the origin of the hysteresis has not been provided so far, several experimental findings ascribe its origin to ionic migration at an applied bias and dielectric polarization that occurs in the perovskite layer. Consistently, a dipole-moment-reduced cation such as formamidinium ion is experimentally reported to quantitatively reduce the hysteresis from perovskite-based devices. By means of a density-functional theory-based set of calculations, we have predicted and characterized guanidinium ion (GA = (+)[C(NH2)3], a zero-dipole moment cation by symmetry)-based organic-inorganic halide perovskite's structural and electronic properties, speculating that such a cation and the alloys it may form with other organic cations can represent a possible chemical solution for the puzzling issue of the hysteresis. PMID:26468971

  16. Modeling and measurement of vesicle pools at the cone ribbon synapse: Changes in release probability are solely responsible for voltage-dependent changes in release.

    PubMed

    Thoreson, Wallace B; Van Hook, Matthew J; Parmelee, Caitlyn; Curto, Carina

    2016-01-01

    Postsynaptic responses are a product of quantal amplitude (Q), size of the releasable vesicle pool (N), and release probability (P). Voltage-dependent changes in presynaptic Ca(2+) entry alter postsynaptic responses primarily by changing P but have also been shown to influence N. With simultaneous whole cell recordings from cone photoreceptors and horizontal cells in tiger salamander retinal slices, we measured N and P at cone ribbon synapses by using a train of depolarizing pulses to stimulate release and deplete the pool. We developed an analytical model that calculates the total pool size contributing to release under different stimulus conditions by taking into account the prior history of release and empirically determined properties of replenishment. The model provided a formula that calculates vesicle pool size from measurements of the initial postsynaptic response and limiting rate of release evoked by a train of pulses, the fraction of release sites available for replenishment, and the time constant for replenishment. Results of the model showed that weak and strong depolarizing stimuli evoked release with differing probabilities but the same size vesicle pool. Enhancing intraterminal Ca(2+) spread by lowering Ca(2+) buffering or applying BayK8644 did not increase PSCs evoked with strong test steps, showing there is a fixed upper limit to pool size. Together, these results suggest that light-evoked changes in cone membrane potential alter synaptic release solely by changing release probability. Synapse 70:1-14, 2016. © 2015 Wiley Periodicals, Inc. PMID:26541100

  17. Zero-dipole molecular organic cations in mixed organic-inorganic halide perovskites: possible chemical solution for the reported anomalous hysteresis in the current-voltage curve measurements

    NASA Astrophysics Data System (ADS)

    Giorgi, Giacomo; Yamashita, Koichi

    2015-11-01

    Starting from a brief description of the main architectures characterizing the novel solar technology of perovskite-based solar cells, we focus our attention on the anomalous hysteresis experimentally found to affect the measurement of the current-voltage curve of such devices. This detrimental effect, associated with slow dynamic reorganization processes, depends on several parameters; among them, the scan rate of the measurements, the architecture of the cell, and the perovskite deposition rate are crucial. Even if a conclusive explanation of the origin of the hysteresis has not been provided so far, several experimental findings ascribe its origin to ionic migration at an applied bias and dielectric polarization that occurs in the perovskite layer. Consistently, a dipole-moment-reduced cation such as formamidinium ion is experimentally reported to quantitatively reduce the hysteresis from perovskite-based devices. By means of a density-functional theory-based set of calculations, we have predicted and characterized guanidinium ion (GA = +[C(NH2)3], a zero-dipole moment cation by symmetry)-based organic-inorganic halide perovskite’s structural and electronic properties, speculating that such a cation and the alloys it may form with other organic cations can represent a possible chemical solution for the puzzling issue of the hysteresis.

  18. Quantitative interpretation of the transition voltages in gold-poly(phenylene) thiol-gold molecular junctions

    SciTech Connect

    Wu, Kunlin; Bai, Meilin; Hou, Shimin; Sanvito, Stefano

    2013-11-21

    The transition voltage of three different asymmetric Au/poly(phenylene) thiol/Au molecular junctions in which the central molecule is either benzene thiol, biphenyl thiol, or terphenyl thiol is investigated by first-principles quantum transport simulations. For all the junctions, the calculated transition voltage at positive polarity is in quantitative agreement with the experimental values and shows weak dependence on alterations of the Au-phenyl contact. When compared to the strong coupling at the Au-S contact, which dominates the alignment of various molecular orbitals with respect to the electrode Fermi level, the coupling at the Au-phenyl contact produces only a weak perturbation. Therefore, variations of the Au-phenyl contact can only have a minor influence on the transition voltage. These findings not only provide an explanation to the uniformity in the transition voltages found for ?-conjugated molecules measured with different experimental methods, but also demonstrate the advantage of transition voltage spectroscopy as a tool for determining the positions of molecular levels in molecular devices.

  19. Nanosecond resistive high-voltage probes for transient ground rise measurement in gas-insulated switchgear. Part I: Newi probes with wire-wound resistors

    NASA Astrophysics Data System (ADS)

    Mitchel, G. R.; Malewski, R.

    1987-05-01

    This paper describes a 5-ns rise-time resistive voltage probe for use up to 150 kV. It is based on a wire-counterwound design and uses low-voltage arms incorporating fast switching diodes for oscilloscope protection. Much attention was paid to reducing inductance in the system through a compact layout, while still ensuring adequate dielectric insulation.

  20. Evaluation on two-port configuration of a Lamé-mode octagonal microelectromechanical systems resonator driven by sliding driving electrodes

    NASA Astrophysics Data System (ADS)

    Tsujishita, Katsuhiro; Tanigawa, Hiroshi; Furutsuka, Takashi; Suzuki, Kenichiro

    2015-06-01

    In this paper we report significant improvements for microelectromechanical system (MEMS) resonators. In our previous work, the reduction in gap between a driving electrode (DE) and a resonant plate was achieved by sliding DEs, showing a clear resonance at 12 MHz. However, it needed a large pull-in voltage and an elaborate measurement technique. In this study, we design soft springs for DEs and evaluate a two-port configuration to cancel feedthrough current. Measurement results show that the pull-in voltage is successfully decreased by one-third that for the previous resonator and a resonance is observed in a fabricated two-port circuit. Such a pull-in voltage can be sufficiently generated from a 2.5 V source in combination with a charge pump circuit. These results are useful for adopting the MEMS resonators to real applications.

  1. Linear particle accelerator with seal structure between electrodes and insulators

    DOEpatents

    Broadhurst, John H. (Golden Valley, MN)

    1989-01-01

    An electrostatic linear accelerator includes an electrode stack comprised of primary electrodes formed or Kovar and supported by annular glass insulators having the same thermal expansion rate as the electrodes. Each glass insulator is provided with a pair of fused-in Kovar ring inserts which are bonded to the electrodes. Each electrode is designed to define a concavo-convex particle trap so that secondary charged particles generated within the accelerated beam area cannot reach the inner surface of an insulator. Each insulator has a generated inner surface profile which is so configured that the electrical field at this surface contains no significant tangential component. A spark gap trigger assembly is provided, which energizes spark gaps protecting the electrodes affected by over voltage to prevent excessive energy dissipation in the electrode stack.

  2. Sputter-deposited fuel cell membranes and electrodes

    NASA Technical Reports Server (NTRS)

    Narayanan, Sekharipuram R. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Chun, William (Inventor); Ruiz, Ron P. (Inventor); Valdez, Thomas I. (Inventor)

    2001-01-01

    A method for preparing a membrane for use in a fuel cell membrane electrode assembly includes the steps of providing an electrolyte membrane, and sputter-depositing a catalyst onto the electrolyte membrane. The sputter-deposited catalyst may be applied to multiple sides of the electrolyte membrane. A method for forming an electrode for use in a fuel cell membrane electrode assembly includes the steps of obtaining a catalyst, obtaining a backing, and sputter-depositing the catalyst onto the backing. The membranes and electrodes are useful for assembling fuel cells that include an anode electrode, a cathode electrode, a fuel supply, and an electrolyte membrane, wherein the electrolyte membrane includes a sputter-deposited catalyst, and the sputter-deposited catalyst is effective for sustaining a voltage across a membrane electrode assembly in the fuel cell.

  3. Electrostatically screened, voltage-controlled electrostatic chuck

    DOEpatents

    Klebanoff, Leonard Elliott (San Ramon, CA)

    2001-01-01

    Employing an electrostatically screened, voltage-controlled electrostatic chuck particularly suited for holding wafers and masks in sub-atmospheric operations will significantly reduce the likelihood of contaminant deposition on the substrates. The electrostatic chuck includes (1) an insulator block having a outer perimeter and a planar surface adapted to support the substrate and comprising at least one electrode (typically a pair of electrodes that are embedded in the insulator block), (2) a source of voltage that is connected to the at least one electrode, (3) a support base to which the insulator block is attached, and (4) a primary electrostatic shield ring member that is positioned around the outer perimeter of the insulator block. The electrostatic chuck permits control of the voltage of the lithographic substrate; in addition, it provides electrostatic shielding of the stray electric fields issuing from the sides of the electrostatic chuck. The shielding effectively prevents electric fields from wrapping around to the upper or front surface of the substrate, thereby eliminating electrostatic particle deposition.

  4. Military Curricula for Vocational & Technical Education. Basic Electricity and Electronics Individualized Learning System. CANTRAC A-100-0010. Module Four: Measuring Current and Voltage in Series Circuits. Study Booklet.

    ERIC Educational Resources Information Center

    Chief of Naval Education and Training Support, Pensacola, FL.

    This individualized learning module on measuring current and voltage in series circuits is one in a series of modules for a course in basic electricity and electronics. The course is one of a number of military-developed curriculum packages selected for adaptation to vocational instructional and curriculum development in a civilian setting. Three…

  5. Focused shock spark discharge drill using multiple electrodes

    DOEpatents

    Moeny, William M. (Albuquerque, NM); Small, James G. (Albuquerque, NM)

    1988-01-01

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

  6. Flexible Ag electrode for quantum dot light-emitting diode

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Pan, Jiangyong; Qingguo, Du; Lei, Wei; Li, Qing; Xia, Jun; Tu, Yan

    2014-08-01

    In this paper, we have fabricated quantum dot light-emitting diode (QD-LED) based on silver (Ag) electrode. The QD-LED with Ag electrode is demonstrated with decreased leakage current, improved luminous efficiency, low turn-on voltages, and saturated emission exhibiting the Commission Internationale de l'Enclairage coordinates of (0.59, 0.40). Meanwhile, compared to the QD-LED with indium tin oxide-coated polyethylene terephthalate electrode, the electroluminescence intensity was enhanced twice for QD-LED based on Ag electrode, and turn-on voltage was reduced to 4.7 V, which was attributed to the higher conductivity and better transmission of Ag electrode.

  7. Current measuring system

    DOEpatents

    Dahl, D.A.; Appelhans, A.D.; Olson, J.E.

    1997-09-09

    A current measuring system is disclosed comprising a current measuring device having a first electrode at ground potential, and a second electrode; a current source having an offset potential of at least three hundred volts, the current source having an output electrode; and a capacitor having a first electrode electrically connected to the output electrode of the current source and having a second electrode electrically connected to the second electrode of the current measuring device. 4 figs.

  8. Fabricating solid carbon porous electrodes from powders

    DOEpatents

    Kaschmitter, J.L.; Tran, T.D.; Feikert, J.H.; Mayer, S.T.

    1997-06-10

    Fabrication is described for conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive deionization, and waste treatment. Electrodes fabricated from low surface area (<50 m{sup 2}/gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon composites with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to high surface area carbons, fuel cell electrodes can be produced. 1 fig.

  9. Fabricating solid carbon porous electrodes from powders

    DOEpatents

    Kaschmitter, James L. (Pleasanton, CA); Tran, Tri D. (Livermore, CA); Feikert, John H. (Livermore, CA); Mayer, Steven T. (San Leandro, CA)

    1997-01-01

    Fabrication of conductive solid porous carbon electrodes for use in batteries, double layer capacitors, fuel cells, capacitive dionization, and waste treatment. Electrodes fabricated from low surface area (<50 m.sup.2 /gm) graphite and cokes exhibit excellent reversible lithium intercalation characteristics, making them ideal for use as anodes in high voltage lithium insertion (lithium-ion) batteries. Electrodes having a higher surface area, fabricated from powdered carbon blacks, such as carbon aerogel powder, carbon aerogel microspheres, activated carbons, etc. yield high conductivity carbon compositives with excellent double layer capacity, and can be used in double layer capacitors, or for capacitive deionization and/or waste treatment of liquid streams. By adding metallic catalysts to be high surface area carbons, fuel cell electrodes can be produced.

  10. Magnetron cathodes in plasma electrode Pockels cells

    DOEpatents

    Rhodes, M.A.

    1995-04-25

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

  11. Magnetron cathodes in plasma electrode pockels cells

    DOEpatents

    Rhodes, Mark A. (Pleasanton, CA)

    1995-01-01

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating. pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal.

  12. Effect of Anode Floating Voltage and its Applications in Characterizing Silicon Drift Detectors

    NASA Astrophysics Data System (ADS)

    Wu, Guang-Guo; Li, Hong-Ri; Liang, Kun; Yang, Ru; Cao, Xue-Lei; Wang, Huan-Yu; An, Jun-Ming; Hu, Xiong-Wei; Han, De-Jun

    2009-04-01

    Anode Boating voltage is predicted and investigated for silicon drift detectors (SDDs) with an active area of 5 mm2 fabricated by a double-side parallel technology. It is demonstrated that the anode Boating voltage increases with the increasing inner ring voltage, and is almost unchanged with the external ring voltage. The anode Boating voltage will not be affected by the back electrode biased voltage until it reaches the full-depleted voltage (-50 V) of the SDD. Theoretical analysis and experimental results show that the anode Boating voltage is equal to the sum of the inner ring voltage and the built-in potential between the p+ inner ring and the n+ anode. A fast checking method before detector encapsulation is proposed by employing the anode Boating voltage along with checking the leakage current, potential distribution and drift properties.

  13. Electrochemical Stability of Model Polymer Electrolyte/Electrode Interfaces

    NASA Astrophysics Data System (ADS)

    Hallinan, Daniel; Yang, Guang

    2015-03-01

    Polymer electrolytes are promising materials for high energy density rechargeable batteries. However, typical polymer electrolytes are not electrochemically stable at the charging voltage of advanced positive electrode materials. Although not yet reported in literature, decomposition is expected to adversely affect the performance and lifetime of polymer-electrolyte-based batteries. In an attempt to better understand polymer electrolyte oxidation and design stable polymer electrolyte/positive electrode interfaces, we are studying electron transfer across model interfaces comprising gold nanoparticles and organic protecting ligands assembled into monolayer films. Gold nanoparticles provide large interfacial surface area yielding a measurable electrochemical signal. They are inert and hence non-reactive with most polymer electrolytes and lithium salts. The surface can be easily modified with ligands of different chemistry and molecular weight. In our study, poly(ethylene oxide) (PEO) will serve as the polymer electrolyte and lithium bis(trifluoromethanesulfonyl) imide salt (LiTFSI) will be the lithium salt. The effect of ligand type and molecular weight on both optical and electrical properties of the gold nanoparticle film will be presented. Finally, the electrochemical stability of the electrode/electrolyte interface and its dependence on interfacial properties will be presented.

  14. Carbon aerogel based electrode material for EAP actuators

    NASA Astrophysics Data System (ADS)

    Kaasik, Friedrich; Torop, Janno; Peikolainen, Anna-Liisa; Koel, Mihkel; Aabloo, Alvo

    2011-04-01

    In this work we report an actuator material, that consist of carbon aerogel, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and poly(vinylidene-co-hexafluoropropylene) (PVdF(HFP)). Actuators were made by using layer-by-layer casting method and they work as a bending actuators. Carbon aerogel is synthesized from 5- methylresorcinol, which is a waste product in oil-shale industry. It makes the material "environmentally green". Carbon aerogels have a very low density and considerable specific surface area. It is generally understood that the large interfacial surface area of electrodes gives rise to better actuation performance; therefore, designing actuators with high specific surface area electrodes is of interest. The assembled three layer actuators require low voltage to operate and work steadily in open air due to non-volatile electrolyte. The electromechanical and electrical characteristics of prepared actuators were examined and compared to our previously reported actuators based on the carbide-derived carbon and activated carbon electrodes. The differences in actuation performance were analyzed in the context of pore characteristics and degree of graphitization of carbons. The gas sorption measurements were performed to characterize pore size distribution. These actuators show high strain, low back-relaxation and low power consumption and they are good for slow-response applications compared to carbon nanotube actuators.

  15. Performance Assessment of Single Electrode-Supported Solid Oxide Cells Operating in the Steam Electrolysis Mode

    SciTech Connect

    X. Zhang; J. E. O'Brien; R. C. O'Brien; N. Petigny

    2011-11-01

    An experimental study is under way to assess the performance of electrode-supported solid-oxide cells operating in the steam electrolysis mode for hydrogen production. Results presented in this paper were obtained from single cells, with an active area of 16 cm{sup 2} per cell. The electrolysis cells are electrode-supported, with yttria-stabilized zirconia (YSZ) electrolytes ({approx}10 {mu}m thick), nickel-YSZ steam/hydrogen electrodes ({approx}1400 {mu}m thick), and modified LSM or LSCF air-side electrodes ({approx}90 {mu}m thick). The purpose of the present study is to document and compare the performance and degradation rates of these cells in the fuel cell mode and in the electrolysis mode under various operating conditions. Initial performance was documented through a series of voltage-current (VI) sweeps and AC impedance spectroscopy measurements. Degradation was determined through long-term testing, first in the fuel cell mode, then in the electrolysis mode. Results generally indicate accelerated degradation rates in the electrolysis mode compared to the fuel cell mode, possibly due to electrode delamination. The paper also includes details of an improved single-cell test apparatus developed specifically for these experiments.

  16. High-voltage compatible, full-depleted CCD

    DOEpatents

    Holland, Stephen Edward (Hercules, CA)

    2007-09-18

    A charge coupled device for detecting electromagnetic and particle radiation is described. The device includes a high-resistivity semiconductor substrate, buried channel regions, gate electrode circuitry, and amplifier circuitry. For good spatial resolution and high performance, especially when operated at high voltages with full or nearly full depletion of the substrate, the device can also include a guard ring positioned near channel regions, a biased channel stop, and a biased polysilicon electrode over the channel stop.

  17. Shielded capacitive electrode

    SciTech Connect

    Kireeff Covo, Michel

    2013-07-09

    A device is described, which is sensitive to electric fields, but is insensitive to stray electrons/ions and unlike a bare, exposed conductor, it measures capacitively coupled current while rejecting currents due to charged particle collected or emitted. A charged particle beam establishes an electric field inside the beam pipe. A grounded metallic box with an aperture is placed in a drift region near the beam tube radius. The produced electric field that crosses the aperture generates a fringe field that terminates in the back surface of the front of the box and induces an image charge. An electrode is placed inside the grounded box and near the aperture, where the fringe fields terminate, in order to couple with the beam. The electrode is negatively biased to suppress collection of electrons and is protected behind the front of the box, so the beam halo cannot directly hit the electrode and produce electrons. The measured signal shows the net potential (positive ion beam plus negative electrons) variation with time, as it shall be observed from the beam pipe wall.

  18. Study of electric discharges between moving electrodes in air

    SciTech Connect

    Andreev, V. V.; Pichugin, Yu. P.; Telegin, V. G.; Telegin, G. G.

    2011-12-15

    A barrier electric discharge excited between a fixed electrode and a rotating electrode covered with a dielectric layer in atmospheric-pressure air is studied experimentally. A distinctive feature of this type of discharge is that it operates at a constant voltage between the electrodes. An advantage of the proposed method for plasma generation in the boundary layer of the rotating electrode (e.g., for studying the influence of plasma on air flows) is the variety of forms of the discharge and conditions for its initiation, simplicity of the design of the discharge system, and ease of its practical implementation.

  19. High-Voltage Droplet Dispenser Developed

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; VanderWal, Randy L.

    2001-01-01

    Various techniques have been applied to deploying individual droplets for many applications, such as the study of the combustion of liquid fuels. Isolated droplet studies are useful in that they allow phenomena to be studied under well-controlled and simplified conditions. A high-voltage droplet dispenser has been developed that is extremely effective in dispensing a wide range of droplets. The dispenser is quite unique in that it utilizes a droplet bias voltage, as well as an ionization pulse, to release the droplet. The droplet is deployed from the end of a needle. A flat-tipped, stainless steel needle attached to a syringe dispenses a known value of liquid that hangs on the needle tip. Somewhat below the droplet is an annular ring electrode. A bias voltage, followed by a voltage pulse, is applied to attract the droplet sufficiently to pull it off the needle. The droplet and needle are oppositely charged relative to the annular electrode. The needle is negatively charged, and the annular ring is positively charged.

  20. Mechanism of voltage production and frequency dependence of the ultrasonic vibration potential

    NASA Astrophysics Data System (ADS)

    Nguyen, Cuong K.; Wang, Shougang; Diebold, Gerald

    2009-05-01

    Imaging with the ultrasonic vibration potential is based on voltage generation by a colloidal or ionic suspension in response to the passage of ultrasound. The polarization within a body arising from the oscillatory displacement in the ultrasonic field produces a current in a pair of external electrodes that is measured as a function of time or frequency. Existing theory gives the current in the electrodes as arising from both a time varying polarization and ionic conduction. Here, experiments are reported that show the production of the polarization current is the dominant mechanism for current generation in soft tissue. Experiments are also reported giving the frequency dependence of the ultrasonic vibration current in canine blood and in several dilutions of aqueous silica suspensions.