Sample records for voltage measurement electrodes

  1. 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

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

    SciTech Connect

    Malík, M., E-mail: michal.malik@tul.cz; Primas, J.; Kopecký, V.; Svoboda, M. [Faculty of Mechatronics, Informatics and Interdisciplinary Studies, Technical University of Liberec, Liberec, 461 17 (Czech Republic)] [Faculty of Mechatronics, Informatics and Interdisciplinary Studies, Technical University of Liberec, Liberec, 461 17 (Czech Republic)

    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.

  3. Breakdown voltage of interelectrode gap between sphere-plane electrodes under ac voltage

    Microsoft Academic Search

    Masakazu Higashiyama; T. Hayama; S. Nakamura; T. Umemura; T. Hirose; Masayuki Hikita; Masahiro Kozako

    2010-01-01

    The breakdown voltage in a small spacing under dc voltage application has been well described with the Paschen law. The present paper differs from the previous works in that we employ ac voltage. The electrode system employed is sphere-plane electrodes and the sphere and\\/or sphere electrodes are coated with an epoxy resin. The breakdown voltage of air gap of the

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Electrodic voltages accompanying stimulated bioremediation of a uraniumcontaminated aquifer

    E-print Network

    Hubbard, Susan

    Click Here for Full Article Electrodic voltages accompanying stimulated bioremediation microbial activity during stimulated bioremediation has limited its implementation. We used spatiotemporal bioremediation of a uraniumcontaminated aquifer, J. Geophys. Res., 115, G00G05, doi:10.1029/2009JG001142. 1

  9. 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 activities in cultured excitable cells. Notably, Mermaid has fast on-off kinetics at warm (B33 1C

  10. Technique eliminates high voltage arcing at electrode-insulator contact area

    NASA Technical Reports Server (NTRS)

    Mealy, G.

    1967-01-01

    Coating the electrode-insulator contact area with silver epoxy conductive paint and forcing the electrode and insulator tightly together into a permanent connection, eliminates electrical arcing in high-voltage electrodes supplying electrical power to vacuum facilities.

  11. Electric field and space charge of spherical electrode at high voltage concentric with a grounded conductive sphere

    Microsoft Academic Search

    Ghaffar Kazkaz

    1998-01-01

    The solution of the space-charge Poisson's equation is presented for a spherical electrode at high voltage concentric with a grounded conductive sphere. The obtained electric field is given in terms of the ion current emitted by the electrode and an integration constant. Both parameters are functions of boundary conditions. Using measured values of the ion current for a range of

  12. Proposed triple-wall, voltage-isolating electrodes for multiple-bias-voltage 3D sensors

    NASA Astrophysics Data System (ADS)

    Parker, Sherwood; Mokhov, N. V.; Rakhno, I. L.; Tropin, I. S.; DaVia, Cinzia; Seidel, S.; Hoeferkamp, M.; Metcalfe, J.; Wang, Rui; Kenney, Christopher; Hasi, Jasmine; Grenier, Philippe

    2012-09-01

    Dividing 3D active-edge silicon sensors into separate sections with a triple-wall sandwich of two trench electrodes separated by an insulating layer, will allow two or more bias voltages to be used simultaneously. Such sensors could be fabricated with only a single group of low-temperature additional steps and may be necessary to prevent a new form of radiation-damage failure in non-uniform radiation fields.

  13. Submicron gap capacitor for measurement of breakdown voltage in air

    NASA Astrophysics Data System (ADS)

    Hourdakis, Emmanouel; Simonds, Brian J.; Zimmerman, Neil M.

    2006-03-01

    We have developed a new method for measuring the value of breakdown voltage in air for electrode separations from 400nmto45?m. The electrodes used were thin film Au lines evaporated on sapphire. The resulting capacitors had an area of 80×80?m2. We demonstrate the ability to deduce the value of the separation of the plates by the value of the capacitance. The data acquired with this method do not agree with Paschen's law for electrode separations below 10?m, as expected from previous experiments. Amongst the improvements of our method are the measurement of plate separation and the very small surface roughness (average of 6nm).

  14. 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-6Al-4V). Following gas conditioning, each TiN-coated aluminum electrode reached ?225?kV bias voltage while generating less than 100?pA of field emission (« less

  15. 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.

  16. Measured radial dependence of the peak sheath voltages present in very high frequency capacitive discharges

    Microsoft Academic Search

    E. V. Barnat; P. A. Miller; G. A. Hebner; A. M. Paterson; Theodoros Panagopoulos; Edward Hammond; J. Holland

    2007-01-01

    The radial distribution of the measured voltage drop across a sheath formed between a 300 mm electrode and an argon plasma discharge is shown to depend on the excitation radio frequency, under constant power and pressure conditions. At a lower frequency of 13.56 MHz, the voltage drop across the sheath is uniform across the 300 mm electrode, while at higher

  17. 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.

  18. Increased hold-off voltage in vacuum gaps with coated electrodes

    Microsoft Academic Search

    R. J. Allen; K. H. Schoenbach

    1996-01-01

    It has been shown that thin film coatings applied to metal electrodes in vacuum increase the breakdown voltage. With a 2 ?m SiO coating on a stainless steel cathode doubling of the DC breakdown voltage compared to that of a bare electrode was achieved. The electric field at breakdown with a coated electrode reached an average value of 650 kV\\/cm.

  19. Low voltage and high transmittance blue-phase liquid crystal displays with corrugated electrodes

    E-print Network

    Wu, Shin-Tson

    Low voltage and high transmittance blue-phase liquid crystal displays with corrugated electrodes January 2010 A low voltage 10 V and high transmittance 85.6% polymer-stabilized blue-phase liquid crystal along the beam path is large, resulting in low voltage and high transmittance. This approach enables

  20. FBG Based Voltage Measurement using PZT Modulation

    Microsoft Academic Search

    Yuan Yao; Benshun Yi

    2006-01-01

    This article proposes a new fiber Bragg grating (FBG) sensor for voltage measurement. Based on the theoretical analysis of the relationship between the PZT electrostriction displacement and the applied voltage, using the characteristic of the FBG measurement - the FBG wavelength drift can reflect the FBG radial strain, a FBG voltage sensor is designed and developed. When the DC exciting

  1. 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.

  2. Arc voltage measurements of the hyperbaric MIG process

    SciTech Connect

    Huismann, G.; Hoffmeister, H. [Univ. der Bundeswehr, Hamburg (Germany)

    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.

  3. Electrometer system measures nanoamps at high voltage

    NASA Technical Reports Server (NTRS)

    Sturman, J. C.; Sharp, G. R.; Robson, R. R.; Stevens, N. J.; Priebe, D. H. F.; Wetli, R. G.

    1974-01-01

    Floating electrometer eliminates major source of error since any leakage from electrometer case, which is at high voltage, appears only as load on high voltage supply and not as part of current being measured. Commands to and data from floating electrometer are transferred across high voltage interface by means of optical channels.

  4. 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.

  5. PEDOT–CNT coated electrodes stimulate retinal neurons at low voltage amplitudes and low charge densities

    NASA Astrophysics Data System (ADS)

    Samba, R.; Herrmann, T.; Zeck, G.

    2015-02-01

    Objective. The aim of this study was to compare two different microelectrode materials—the conductive polymer composite poly-3,4-ethylenedioxythiophene (PEDOT)–carbon nanotube(CNT) and titanium nitride (TiN)—at activating spikes in retinal ganglion cells in whole mount rat retina through stimulation of the local retinal network. Stimulation efficacy of the microelectrodes was analyzed by comparing voltage, current and transferred charge at stimulation threshold. Approach. Retinal ganglion cell spikes were recorded by a central electrode (30 ?m diameter) in the planar grid of an electrode array. Extracellular stimulation (monophasic, cathodic, 0.1–1.0 ms) of the retinal network was performed using constant voltage pulses applied to the eight surrounding electrodes. The stimulation electrodes were equally spaced on the four sides of a square (400 × 400 ?m). Threshold voltage was determined as the pulse amplitude required to evoke network-mediated ganglion cell spiking in a defined post stimulus time window in 50% of identical stimulus repetitions. For the two electrode materials threshold voltage, transferred charge at threshold, maximum current and the residual current at the end of the pulse were compared. Main results. Stimulation of retinal interneurons using PEDOT–CNT electrodes is achieved with lower stimulation voltage and requires lower charge transfer as compared to TiN. The key parameter for effective stimulation is a constant current over at least 0.5 ms, which is obtained by PEDOT–CNT electrodes at lower stimulation voltage due to its faradaic charge transfer mechanism. Significance. In neuroprosthetic implants, PEDOT–CNT may allow for smaller electrodes, effective stimulation in a safe voltage regime and lower energy-consumption. Our study also indicates, that the charge transferred at threshold or the charge injection capacity per se does not determine stimulation efficacy.

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

    DOEpatents

    Vail III, William Banning; Momii, Steven Thomas

    2003-06-10

    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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    BastaniNejad, M.; Elmustafa, A. A.; Forman, E.; Clark, J.; Covert, S.; Grames, J.; Hansknecht, J.; Hernandez-Garcia, C.; Poelker, M.; Suleiman, R.

    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.

  9. Thermoelectric corrections to quantum voltage measurement

    NASA Astrophysics Data System (ADS)

    Stafford, Charles; Bergfield, Justin

    2014-03-01

    The voltage measured by a floating probe of a nonequilibrium quantum system is shown to exhibit nontrivial thermoelectric corrections at finite temperature. The voltage probe is modelled as a scanning potentiometer/thermometer that is allowed to equilibrate with a quantum system via local tunnel coupling. Once equilibrated, the net electrical and heat currents flowing into the probe are zero. This generalizes Buettiker's theory of voltage measurement at zero temperature to finite-temperature systems. In a quantum conductor with electrical bias, it is shown that the probe temperature generally differs from ambient temperature due to Peltier cooling/heating within the system, and that the temperature difference can be sizeable for modest bias voltages. Conversely, if the probe is held at ambient temperature, its voltage is shifted from the equilibrated value, leading to a significant error in voltage measurement. However, if there is a large thermal coupling of the probe to the ambient environment, thermal coupling between the probe and system becomes unimportant, and the voltage measurement becomes similar to the process at zero temperature, with negligible thermoelectric corrections. Work supported by U.S. Department of Energy under Award No. DE-SC0006699.

  10. Measured radial dependence of the peak sheath voltages present in very high frequency capacitive discharges

    SciTech Connect

    Barnat, E. V.; Miller, P. A.; Hebner, G. A.; Paterson, A. M.; Panagopoulos, Theodoros; Hammond, Edward; Holland, J. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1423 (United States); Applied Materials, 974 Arques Avenue, Sunnyvale, California 94086 (United States)

    2007-05-14

    The radial distribution of the measured voltage drop across a sheath formed between a 300 mm electrode and an argon plasma discharge is shown to depend on the excitation radio frequency, under constant power and pressure conditions. At a lower frequency of 13.56 MHz, the voltage drop across the sheath is uniform across the 300 mm electrode, while at higher frequencies of 60 and 162 MHz the voltage drop becomes radially nonuniform. The magnitude and spatial extent of the nonuniformity become greater with increasing frequency.

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

    SciTech Connect

    Wu, Kunlin; Bai, Meilin; Hou, Shimin, E-mail: smhou@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices, Department of Electronics, Peking University, Beijing 100871 (China); Sanvito, Stefano [School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2 (Ireland)

    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.

  12. High-Voltage Measurements and Isolation

    NSDL National Science Digital Library

    This tutorial is part of the National Instruments Measurement Fundamentals series. Each tutorial in this series teaches you a specific topic of common measurement applications by explaining theoretical concepts and providing practical examples. There are many issues to consider when measuring high voltage. When specifying a data acquisition (DAQ) system, the first question one should ask is whether the system will be safe. Making high-voltage measurements can be hazardous to the equipment, to the unit under test, and to you and your colleagues. This tutorial covers the concept of isolation, as well as discussing National Instruments' isolated products. A PDF of the material is available for download as well.

  13. Measuring Multi-Megavolt Diode Voltages

    Microsoft Academic Search

    N. R. Pereira; S. B. Swanekamp; B. V. Weber; R. J. Commisso; D. D. Hinshelwood; S. J. Stephanakis

    2002-01-01

    The voltage in high-power diodes can be determined by measuring the Compton electrons generated by the diode’s bremsstrahlung radiation. This technique is implemented with a Compton-Hall (C-H) voltmeter that collimates the bremsstrahlung onto a Compton target and bends the emitted Compton electron orbits off to the side with an applied magnetic field off to Si pin diode detectors. Voltage is

  14. Measuring Multi-Megavolt Diode Voltages

    Microsoft Academic Search

    N. R. Pereira; S. B. Swanekamp; B. V. Weber; R. J. Commisso; D. D. Hinshelwood; S. J. Stephanakis

    2002-01-01

    The voltage in high-power diodes can be determined by measuring the Compton electrons generated by the diode's bremsstrahlung radiation. This technique is implemented with a Compton-Hall (C-H) voltmeter that collimates the bremsstrahlung onto a Compton target and bends the emitted Compton electron orbits off to the side with an applied magnetic field off to Si pin diode detectors. Voltage is

  15. 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 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.« less

  16. Electric field and space charge of spherical electrode at high voltage concentric with a spherical grounded conductive target

    Microsoft Academic Search

    Ghaffar Kazkaz

    1996-01-01

    Point electrodes at high voltage are used in many diverse electrostatic particle charging and deposition applications, such as electrostatic liquid and powder coating, aerosol and ash filtrations, and pesticide spraying of agricultural crops. The electric field and the space charge generated by the high voltage electrode are important parameters for particle charging and particle deposition. To improve system design and

  17. Partial discharge and breakdown characteristics on needle\\/dielectrics composite electrode systems under pulse voltage

    Microsoft Academic Search

    N. Sakamoto; Y. Kuninaka; H. Ueno; H. Nakayama

    2001-01-01

    Studied the discharge characteristics on the composite electrode under a pulse voltage in N2. The configuration is a needle-plane one, in which the needle is in contact with solid dielectrics, with a narrow gap. The configuration has a plurality of places of the local high field, namely a needle tip and another a triple junction. To examine a local corona

  18. Using fast moving electrode to achieve overvoltage breakdown of gas switch stressed with high direct voltages.

    PubMed

    Zou, X B; Shi, H T; Xie, H; Wang, Xinxin; Zhang, Guixin

    2015-03-01

    A small-scale fast risetime gas switch attached to a 50 ? pulse forming line is tested. It includes a fast moving electrode and a fixed electrode. For the applied direct voltages, such as 2.8 kV, 2.0 kV, and 1.0 kV, the risetimes of this switch are tested to be ?3.8 ns, ?2.3 ns, and ?1.1 ns, respectively, while the risetimes of a switch with two fixed electrodes are about ?10.1 ns, ?9.0 ns, and ?3.6 ns. The results of high-speed photography and laser interferometry reveal that the moving electrode will obviously shorten discharge spark length but almost will not change the inter-electrodes gas pressure. The reason of shortening spark length is the existence of the discharge time delay of gas switch. After moving to the static breakdown spacing, the fast moving electrode will move on for an additional distance within the discharge time delay, which makes gas switch achieve overvoltage breakdown under high direct voltages and therefore leads to shorter spark length and faster switch risetime. PMID:25832256

  19. Flexible viologen electrochromic devices with low operational voltages using reduced graphene oxide electrodes.

    PubMed

    Palenzuela, Jesús; Viñuales, Ana; Odriozola, Ibon; Cabañero, Germán; Grande, Hans J; Ruiz, Virginia

    2014-08-27

    Reduced graphene oxide (RGO) films have been electrodeposited on indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrates from graphene oxide (GO) solutions, and the resulting flexible transparent electrodes have been used in electrochromic devices of ethyl viologen (EtV(2+)). The electrochromic performance of devices with bare ITO-PET electrodes and ITO-PET coated with RGO has been compared. Under continuous cycling tests up to large voltages, the RGO film was oxidized and dispersed in the electrochromic mixture. The resulting devices, which contained GO and RGO in the electrochromic mixture, showed lower switching voltages between the colored and bleached states. This electrocatalytic activity of the solution-phase GO/RGO pair toward the electrochemical reaction of the electrochromic redox couple (the dication EtV(2+) and the radical cation EtV(+•)) allowed devices with an optical contrast higher than the contrast of those free of GO at the same applied voltage. PMID:25090050

  20. Measurement of very-fast-voltage rise curve due to gap discharge using coupled transmission lines in distributed constant system

    Microsoft Academic Search

    Ken Kawamata; Shigeki Minegishi; Akira Haga; Risaburo Sato

    1997-01-01

    A measurement method of very-fast-voltage rise curves due to gap discharge using the coupled transmission lines was examined to discuss a electromagnetic noise source from a viewpoint of electromagnetic compatibility (EMC). The measurement system consists of a distributed constant line system, because the voltage transients were very rapid. A characteristic of the gap electrode, which has a matched impedance for

  1. 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.

  2. [Clinical evaluation of the voltage gradient method for root canal measurement].

    PubMed

    Nakamura, M; Nakamura, Y

    1989-10-01

    The voltage gradient method for root canal measurement was evaluated in vivo and in vitro. For the evaluation in vivo, 25 single root teeth, were employed. The working length was measured by bipolor or monopolor electrode. After measurement, the electrode was fixed on the tooth, and the tooth was extracted. Radiograph was taken from 12 directions perpendicular to longer axis of tooth, and the relation between anatomical foramen, physiological foramen and the attained position of electrode tip was assessed. In the evaluation in vitro, 7 extracted teeth were used, for which the positions of anatomical foramen and physiological foramen had been determined in advance from radiograph, in order to determine the influence of the root canal irrigants and medicaments. The electrode was fixed on electronic calipers and direct reading of the movement. Root canal irrigants and medicaments were injected into root canal, and the measurements were evaluated. The results were as follows: (1) In the cases of 22 teeth measured by monopolar electrode in vivo, the electrode tip was within 0.5mm from physiological foramen except one tooth. (2) In the cases of 3 teeth measured by monopolar electrode in vivo, the electrode tip was within 0.4mm from anatomical foramen. (3) In the cases, where electrolyte solution was filled in root canal and measurement was made by bipolar in the evaluation in vitro, the results of measurement were stable, and the electrode tip tended to be slightly closer to coronal direction from physiological foramen. (4) In the cases where non-electrolyte solution was filled in root canal and measurement was made by bipolar electrode in the evaluation in vitro, the results of measurement were not stable, and the electrode tip tended to be closer to the apex from physiological foramen. (5) In the case of the evaluation in vitro, where electrolyte solution was filled in root canal and measurement was made by monopolar electrode, the electrode tip tended to be a little closer to the front than the anatomical foramen. (6) In the evaluation in vitro, where non-electrolyte solution was filled in root canal and measurement was made by monopolar, the measurement was not achievable. (7) 10% NaOCl solution was found to be very useful as electrolyte solution filled in root canal to search physiological foramen by this measurement method. The above results suggest that the voltage gradient method for root canal measurement is highly reliable because root canal morphology at the apex can be directly in identified. PMID:2489340

  3. 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

  4. 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.

  5. Electrochemical dealloying using pulsed voltage waveforms and its application for supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Zhan, Yawen; Bian, Haidong; Li, Zhe; Tsang, Chun-Kwan; Lee, Chris; Cheng, Hua; Shu, Shiwei; Li, Yang Yang; Lu, Jian

    2014-07-01

    Dealloying is an important industrial technique for generating nanoporous metallic structures by selectively leaching out the more reactive metal component from an alloy material. A constant voltage is often applied to facilitate the dealloying process. Here we report the first study on dealloying with the application of a voltage waveform-specifically, pulsed voltage waveforms are applied for dealloying Ni-Cu alloys. It is found that pulsed dealloying voltage waveforms can exert a strong impact on the dealloying process by 1) significantly lowering the compositional threshold of the more reactive metal component for the dealloying reaction to take place, 2) more thoroughly removing the more reactive metal component and thus producing a porous metal of higher purity and higher porosity (volume fraction of voids), and 3) greatly affecting the morphology of the generated porous metal structure (e.g., leading to significantly thinner ligaments). The nanoporous metallic materials obtained by the pulsed voltage waveform enable supercapacitor electrodes of significantly better performance than the counterpart dealloyed with a constant voltage.

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

    E-print Network

    Williams, K.H.

    2010-01-01

    and current-power relationships between measurement and reference electrodes exhibited a galvanicCurrent- and power-densities are in excellent agreement with those reported for sulfide-dependent galvanic

  7. A Low-Power\\/Low-Voltage CMOS Wireless Interface at 5.7 GHz With Dry Electrodes for Cognitive Networks

    Microsoft Academic Search

    Nuno Sérgio Dias; João Paulo Carmo; Paulo Mateus Mendes; José Higino Correia

    2011-01-01

    This paper describes a low-power\\/low-voltage CMOS wireless interface (CMOS-WiI) at 5.7 GHz with dry electrodes for congnitive networks. The electrodes are 4 4 microtip arrays and acquire electroencephalogram (EEG) signals in key- points for processing. The CMOS-WiI was fabricated in a UMC 0.18 RF CMOS process and its total power consumption is 23 mW with a voltage-supply of only 1.5

  8. 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...

  9. 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.

  10. A consistent approach to estimate the breakdown voltage of high voltage electrodes under positive switching impulses

    NASA Astrophysics Data System (ADS)

    Arevalo, L.; Wu, D.; Jacobson, B.

    2013-08-01

    The main propose of this paper is to present a physical model of long air gap electrical discharges under positive switching impulses. The development and progression of discharges in long air gaps are attributable to two intertwined physical phenomena, namely, the leader channel and the streamer zone. Experimental studies have been used to develop empirical and physical models capable to represent the streamer zone and the leader channel. The empirical ones have led to improvements in the electrical design of high voltage apparatus and insulation distances, but they cannot take into account factors associated with fundamental physics and/or the behavior of materials. The physical models have been used to describe and understand the discharge phenomena of laboratory and lightning discharges. However, because of the complex simulations necessary to reproduce real cases, they are not in widespread use in the engineering of practical applications. Hence, the aim of the work presented here is to develop a model based on physics of the discharge capable to validate and complement the existing engineering models. The model presented here proposes a new geometrical approximation for the representation of the streamer and the calculation of the accumulated electrical charge. The model considers a variable streamer region that changes with the temporal and spatial variations of the electric field. The leader channel is modeled using the non local thermo-equilibrium equations. Furthermore, statistical delays before the inception of the first corona, and random distributions to represent the tortuous nature of the path taken by the leader channel were included based on the behavior observed in experimental tests, with the intention of ensuring the discharge behaved in a realistic manner. For comparison purposes, two different gap configurations were simulated. A reasonable agreement was found between the physical model and the experimental test results.

  11. Atomic layer deposition encapsulated activated carbon electrodes for high voltage stable supercapacitors.

    PubMed

    Hong, Kijoo; Cho, Moonkyu; Kim, Sang Ouk

    2015-01-28

    Operating voltage enhancement is an effective route for high energy density supercapacitors. Unfortunately, widely used activated carbon electrode generally suffers from poor electrochemical stability over 2.5 V. Here we present atomic layer deposition (ALD) encapsulation of activated carbons for high voltage stable supercapacitors. Two-nanometer-thick Al2O3 dielectric layers are conformally coated at activated carbon surface by ALD, well-maintaining microporous morphology. Resultant electrodes exhibit excellent stability at 3 V operation with 39% energy density enhancement from 2.5 V operation. Because of the protection of surface functional groups and reduction of electrolyte degradation, 74% of initial voltage was maintained 50 h after full charge, and 88% of capacitance was retained after 5000 cycles at 70 °C accelerated test, which correspond to 31 and 17% improvements from bare activated carbon, respectively. This ALD-based surface modification offers a general method to enhance electrochemical stability of carbon materials for diverse energy and environmental applications. PMID:25548826

  12. 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.

  13. Comparison of Copper and Stainless Steel Used for Low Voltage Electrode in Wire-to-Plane Electrode Configuration for NO x Treatment

    Microsoft Academic Search

    Robert Gasparik; Chobei Yamabe; Satoshi Ihara; Saburoh Satoh

    1998-01-01

    Copper and stainless steel have been investigated as low voltage electrodes in wire-to-plane electrode configuration under conditions of DC positive streamer corona discharge. Copper has been chosen due to its well-known catalytic activity while, on the other hand, stainless steel was selected as an opposite extreme to copper---due to its high passivity. The initial gas contained 400 ppm NO\\/N2, 10%

  14. Measurement of partial discharges at rapidly changing voltages

    Microsoft Academic Search

    Elisabeth Lindell; Tord Bengtsson; Jorgen Blennow; Stanislaw M. Gubanski

    2008-01-01

    This work presents a measuring system for PDs at repetitive voltages with short rise times, based on a coupling device adapted for this kind of voltages and a method for removing contributions from the applied voltage. The potential of the system has been demonstrated through measurements of PDs around a needle in air at voltages of 5.5 kV - 9.5

  15. In situ measurements of electron-beam-induced surface voltage of highly resistive materials

    NASA Astrophysics Data System (ADS)

    Hodges, Joshua

    This study presents the development, calibration, characterization, and use of new instrumentation for in situ measurements of electron-beam-induced surface voltage. The instrument capabilities allow for measurements of a full range of insulating materials that are of concern to NASA spacecraft charging experts. These measurements are made using moveable capacitive sensor electrodes that can be swept across the sample using an in vacu stepper motor. Testing has shown a voltage range of more than ±30 kV with a low-voltage resolution of 0.2 V. The movable sensors allow for a radial measurement of surface voltage with spatial resolution as low as 1.5 mm. The instrumentation has response time of ˜7 s from the time the beam is shut off until the probe is in position to take data and uses computer automation to stabilize the system and acquire data over the period of several days or longer. Three types of measurements have been made on two prototypical polymeric spacecraft materials, Low-density Polyethylene (LDPE) and polyimide (Kapton™ HN), to illustrate the research capabilities of the new system. Surface voltage measurements were made periodically during the charging process using a pulsed electron beam and subsequently as the surface voltage discharged to a grounded substrate; these were used to obtain information about the material's electron yields and bulk resistivity. The spatial profile of the voltage across the sample surface was also measured by sweeping the electrode across the surface. Subsequent measurements monitored the time evolution of the magnitude and spatial charge distribution as charge dispersed radially across the sample surface. The results of these measurements are present and compared to literature values validating the instrument's effectiveness.

  16. Glass electrode impendance and its measurement on-line

    SciTech Connect

    Gray, J.R. [Rosemount Analytical Co., Irvine, CA (United States)

    1995-12-31

    The on-line measurement of glass electrode and reference impedance is reviewed in terms of its usefulness as a diagnostic and predictive maintenance tool. The physical characteristics of the pH electrode, which give rise to the measured impedance are examined. The measurement of impedance both in the laboratory and on-line, are analyzed based on the impedance behavior of the glass electrode and its effect of the measurement. Factors influencing the measured impedance are identified.

  17. 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

    The effect of acid concentration on the performance of the iron-titanium redox flow cell was studied. When the acidity was increased, open-circuit voltages decreased on the titanium side but load voltages increased due to decreased polarization. The best load voltage occurs when there is high acidity on the titanium side coupled with low acidity on the iron side, but such cells show voltage losses with repeated cycling because of the diffusion of acid through the membrane. No membrane tested has been found capable of maintaining the differences in acidity. Chelating agents show some promise in reducing polarization at the Ti electrode and thus improving energy efficiency.

  18. 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.

  19. 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.

  20. Energy from CO2 using capacitive electrodes--theoretical outline and calculation of open circuit voltage.

    PubMed

    Paz-Garcia, J M; Schaetzle, O; Biesheuvel, P M; Hamelers, H V M

    2014-03-15

    Recently, a new technology has been proposed for the utilization of energy from CO2 emissions (Hamelers et al., 2014). The principle consists of controlling the dilution process of CO2-concentrated gas (e.g., exhaust gas) into CO2-dilute gas (e.g., air) thereby extracting a fraction of the released mixing energy. In this paper, we describe the theoretical fundamentals of this technology when using a pair of charge-selective capacitive electrodes. We focus on the behavior of the chemical system consisting of CO2 gas dissolved in water or monoethanolamine solution. The maximum voltage given for the capacitive cell is theoretically calculated, based on the membrane potential. The different aspects that affect this theoretical maximum value are discussed. PMID:24461836

  1. Two noniterative algorithms for locating inclusions using one electrode measurement of electric impedance tomography

    NASA Astrophysics Data System (ADS)

    Hakula, Harri; Hyvönen, Nuutti

    2008-10-01

    The aim of electric impedance tomography is to gather information on the conductivity inside a physical body from boundary measurements of current and voltage. In many situations of practical importance, the investigated object has known constant background conductivity, but is contaminated by embedded inhomogeneities. In this work, we test numerically two noniterative algorithms for locating such inclusions using only one electrode measurement pair of impedance tomography. The first method is based on the concept of convex source support and has its origins in the works of Kusiak and Sylvester. The other one is the effective dipole method of Hanke. We show that these algorithms are useful in the framework of electrode measurements, but also point out some restrictions to their applicability. Our measurements are simulated using the complete electrode model, which is in good agreement with real-life data.

  2. The effects of voltage waveform factors on cable life estimation using measured distorted voltages

    Microsoft Academic Search

    Giovanni Mazzanti; Gaetano Passarelli; Angela Russo; Paola Verde

    2006-01-01

    This work investigates expected life reduction of power cables under harmonic pollution, by processing the results of voltage harmonics measurements. Life estimates come from a life model developed by the authors in former studies, used here in its complete form, with all voltage waveform factors, i.e. peak, shape and rms factor. The application regards MV XLPE-insulated cables. The whole day

  3. Measurements of electrode temperature evolution by laser light reflection

    NASA Astrophysics Data System (ADS)

    Kempkens, H.; Byszewski, W. W.; Gregor, P. D.; Lapatovich, W. P.

    1990-04-01

    The electrode temperature rise during the starting of an arc discharge lamp has been measured using the temperature-dependent reflection coefficient of He-Ne laser light from metal surfaces. Lock-in techniques permit temporal resolution of about 3 ms, which is adequate to resolve 60-Hz phenomena such as electrode heating during the ac cycle. Calibration curves obtained by pyrometric measurements of constant-current tungsten ribbon lamps were used to relate the observed signal during electrode heating to its temperature. The technique described affords a nonintrusive method for measuring transient electrode temperature in an optically clustered environment with an accuracy of about 20%.

  4. Investigations of noise in measurements of electronic voltage standards

    Microsoft Academic Search

    Thomas J. Witt; Yi-hua Tang

    2005-01-01

    We have investigated noise in measurements of the 10 V outputs of electronic voltage standards based on Zener diode references (Zeners). Zener outputs were compared to NIST Josephson standards using a digital voltmeter (DVM) to measure voltage differences. Because of the presence of serially correlated noise, the data were analyzed by calculating estimated Allan variances which were then used to

  5. Phasor measurement placement for voltage stability analysis of power systems

    Microsoft Academic Search

    L. Mili; T. Baldwin; R. Adapa

    1990-01-01

    The use of real-time phasor measurements for voltage stability analysis of power systems is considered. Two schemes of phasor measurement unit (PMU) placement have been investigated. In the first scheme, PMUs are used as pilot points for the secondary voltage control of a power system. Several criteria for pilot point selections are reviewed and assessed. In the second scheme, the

  6. Frequency response measurements in battery electrodes

    NASA Technical Reports Server (NTRS)

    Thomas, Daniel L.

    1992-01-01

    Electrical impedance spectroscopy was used to investigate the behavior of porous zinc, silver, cadmium, and nickel electrodes. State of charge could be correlated with impedance data for all but the nickel electrodes. State of health was correlated with impedance data for two AgZn cells, one apparently good and the other bad. The impedance data was fit to equivalent circuit models.

  7. Using compound electrodes in electrical impedance tomography.

    PubMed

    Hua, P; Woo, E J; Webster, J G; Tompkins, W J

    1993-01-01

    In electrical impedance tomography, we inject currents and measure voltages to estimate an object's resistivity distribution. The electrode configuration affects measured voltage data because the electrode-skin contact impedance is high and varies with electrode location. We developed a compound electrode which is composed of two electrodes: a large outer electrode to inject current and a small inner electrode to sense voltage. We used these compound electrodes to measure voltages from a physical phantom. We showed that the measured voltages from the compound electrodes are smaller in amplitude than those from conventional electrodes. This demonstrates that the compound electrode can minimize contact impedance voltage drop from the measured data. We used a finite element model for the compound electrode and incorporated the model into the regularized Newton-Raphson reconstruction algorithm. We performed a sensitivity study and showed that the reconstructed resistivity distributions are less dependent on the unknown contact resistance values for a compound electrode than a conventional electrode and that the use of a compound electrode results in improved images for the reconstruction algorithm. PMID:8468073

  8. Comparison of Copper and Stainless Steel Used for Low Voltage Electrode in Wire-to-Plane Electrode Configuration for NO x Treatment

    NASA Astrophysics Data System (ADS)

    Gasparik, Robert; Yamabe, Chobei; Ihara, Satoshi; Satoh, Saburoh

    1998-10-01

    Copper and stainless steel have been investigated as low voltage electrodes in wire-to-plane electrode configuration under conditions of DC positive streamer corona discharge. Copper has been chosen due to its well-known catalytic activity while, on the other hand, stainless steel was selected as an opposite extreme to copper—due to its high passivity. The initial gas contained 400 ppm NO/N2, 10% O2, and water vapors or 40% aqueous solution citric acid. Removal rates of NOx have been calculated as a function of the applied voltage. Results have shown that the highest removal rate, 56% for NO, have been obtained while employing Cu plate and citric acid. We suppose that Cu participates in the process of treatment, while stainless remains inactive. Therefore, while using a stainless steel plate, removal rates have reached lower values than while employing a copper plate.

  9. 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.

  10. A practical approach to electrode-skin impedance unbalance measurement.

    PubMed

    Spinelli, Enrique M; Mayosky, Miguel A; Pallás-Areny, Ramon

    2006-07-01

    Unbalance between electrode-skin impedances is a major problem in biopotential recordings, leading to increased power-line interference. This paper proposes a simple, direct method to measure that unbalance at power-line frequency (50-60 Hz), thus allowing the determination of actual recording conditions for biopotential amplifiers. The method is useful in research, amplifier testing, electrode design and teaching purposes. It has been experimentally validated by using both phantom impedances and real electrode-skin impedances. PMID:16830954

  11. An electrode polarization impedance based flow sensor for low water flow measurement

    NASA Astrophysics Data System (ADS)

    Yan, Tinghu; Sabic, Darko

    2013-06-01

    This note describes an electrode polarization impedance based flow sensor for low water flow measurement. It consists of two pairs of stainless steel electrodes set apart and inserted into a non-conductive flow tube with each pair of electrodes placed diametrically at the opposite sides. The flow sensor is modeled as a typical four-electrode system of which two electrodes are current-carrying and the other two serve as output pick ups. The polarization impedances of the two current carrying electrodes are affected by water flows resulting in changes of differential potential between the two pick-up electrodes which are separated by the same fluid. The interrogation of the two excitation electrodes with dc biased ac signals offers significantly higher sensor sensitivities to flow. The prototype flow sensor constructed for a 20 mm diameter pipeline was able to measure water flow rate as low as tested at 1.06 l h-1 and remained sensitive at a flow rate of 25.18 l h-1 when it was driven with a sinusoidal voltage at 1000 Hz with a peak ac amplitude of 2 V and a dc offset of +8 V. The nonlinear characteristics of the sensor response indicate that the sensor is more sensitive at low flows and will not be able to measure at very high flows. Additional experiments are needed to evaluate the influences of impurities, chemical species, ions constituents, conductivity and temperature over a practical range of residential water conditions, the effects of fluctuating ground signals, measurement uncertainty, power consumption, compensation of effects and practical operations. The flow sensor (principle) presented may be used as (in) a secondary sensor in combination with an existing electronic water meter to extend the low end of measurement range in residential water metering.

  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. [Max-Planck-Institute for Extraterrestrial Physics, Garching 85748 (Germany); Zhang Wengui; Ma, J. X. [Department of Modern Physics, CAS Key Laboratory of Basic Plasma Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    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. Diagnostic measurements of high voltage insulation using current comparator technology

    Microsoft Academic Search

    A. Bulinski; E. So; S. Bamji; Y. Chen; J. Densley; J.-M. Braun

    1994-01-01

    The 60 Hz dielectric loss measurements in high voltage cable insulation containing water trees are described. A current-comparator-based high voltage capacitance bridge has been employed to isolate the small loss currents from the large quadrature (capacitive) currents. It is shown that water trees introduce higher harmonics into the loss current waveform and that the total harmonic distortion of the loss

  14. Time resolved measurements of electroluminescence in XLPE under impulse voltage conditions

    SciTech Connect

    Kaufhold, M.; Bamji, S.S.; Bulinski, A.T. [National Research Council Canada, Ottawa, Ontario (Canada)

    1996-12-31

    Time resolved electroluminescence (EL) measurements were performed on high voltage grade XLPE cable insulation using negative impulse voltages of different shape and duration. To create divergent fields in the insulation, needle electrodes made of semiconductive polymer were used. It is shown that the El emission probability is independent of the impulse rise time but increases with the impulse fall time and amplitude. Independently of the impulse shape and duration, EL pulses are always grouped into two distinct time intervals between which there is no El activity. The first El period begins at the rising portion of the impulse and the second at the falling portion when the impulse voltage drops below 50% of its peak value. EL emission during the first interval is believed to be caused by electron injection and the impact excitation processes, whereas the EL in the second interval is seen to be due to the local electric field reversal and the electron-hole recombination.

  15. 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.

  16. 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.

  17. High voltage DC breakdown initiation of cleaned vs. non-cleaned 304 LMC and 304 L stainless steel electrodes

    Microsoft Academic Search

    M. Dolak; L. Garbini; M. Green

    2000-01-01

    The effect of surface contamination, material grade and surface finish on high voltage DC breakdown has been investigated. A simplified parallel plane gap test geometry has been used to model the electron gun structure in the VA-889F klystron. This klystron has exhibited arcing between the stainless steel focus electrode and copper anode during in-process high-pot testing to 50 kV DC.

  18. A high current, high voltage solid-state pulse generator for the NIF Plasma Electrode Pockels Cell

    Microsoft Academic Search

    P. A. Arnold; F. Barbosa; E. G. Cook; B. C. Hickman; G. L. Akana; C. A. Brooksby

    2007-01-01

    A high current, high voltage, all solid-state pulse modulator has been developed for use in the Plasma Electrode Pockels Cell (PEPC) subsystem in the National Ignition Facility. The MOSFET-switched pulse generator, designed to be a more capable plug-in replacement for the thyratron-switched units currently deployed in NIF, offers unprecedented capabilities including burst-mode operation, pulse width agility and a steady-state pulse

  19. Dielectrophoretic capture voltage spectrum for measurement of dielectric properties and separation of cancer cells

    PubMed Central

    Wu, Liqun; Lanry Yung, Lin-Yue; Lim, Kian-Meng

    2012-01-01

    In this paper, a new dielectrophoresis (DEP) method based on capture voltage spectrum is proposed for measuring dielectric properties of biological cells. The capture voltage spectrum can be obtained from the balance of dielectrophoretic force and Stokes drag force acting on the cell in a microfluidic device with fluid flow and strip electrodes. The method was demonstrated with the measurement of dielectric properties of human colon cancer cells (HT-29 cells). From the capture voltage spectrum, the real part of Clausius–Mossotti factor of HT-29 cells for different frequencies of applied electric field was obtained. The dielectric properties of cell interior and plasma membrane were then estimated by using single-shell dielectric model. The cell interior permittivity and conductivity were found to be insensitive to changes in the conductivity of the medium in which the cells are suspended, but the measured permittivity and conductivity of cell membrane were found to increase with the increase of medium conductivity. In addition, the measurement of capture voltage spectrum was found to be useful in providing the optimum operating conditions for separating HT-29 cells from other cells (such as red blood cells) using dielectrophoresis. PMID:22662097

  20. Development of an optical instrument transformer for DC voltage measurement

    SciTech Connect

    Kurosawa, K.; Yoshida, S. (Tokyo Electric Power Co. (Japan)); Mori, E.; Takahashi, G.; Saito, S. (Hitachi Ltd., Tokyo (Japan))

    1993-10-01

    This paper deals with the principles, design, assembly, testing results and practical application of a new type of optical voltage instrument transformer based on the Pockels effect, developed for the measurement of DC voltage, with a view to the protection and control of DC power transmission systems including frequency changer power equipment. In order to develop more accurate devices, the authors conceived a new scheme capable of overcoming the particular problems of DC voltage measurement which cause measurement errors. In this scheme, the DC voltage to be measured is chopped and applied to the Pockels crystal. An optical DC voltage instrument transformer was developed and tested using this scheme. The results of the factory tests showed that the characteristics of the new device conform with the required specifications of DC voltage instrument transformers for the protection and control of frequency changer power equipment. The results of field tests conducted for 1 year at an operating frequency conversion substation confirmed that the device is of adequate reliability. The new device has been practically applied in a frequency conversion power system of the Tokyo Electric Power Co., Inc since May 1992.

  1. Accurate voltage phasor measurement in a series-compensated network

    SciTech Connect

    Lambert, J.; McNabb, D. (Hydro-Quebec, Montreal, Quebec (Canada)); Phadke, A.G. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1994-01-01

    This paper describes the feasibility studies concerning an accurate voltage phasor measurement in series-compensated network undergoing large disturbances. The principal modes of distortions in such a network are described. Some of these modes are changing with the fundamental frequency. The phasor evaluation is based on a new digital filter approach in which the fundamental frequency is estimated using a least-square algorithm. The need to have special potential (voltage) transformers is also discussed. This approach would be used in a shunt reactor switching scheme for an overall voltage control of a transmission network.

  2. Spark gap with low breakdown voltage jitter

    SciTech Connect

    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.

  3. Spark gap with low breakdown voltage jitter

    DOEpatents

    Rohwein, G.J.; Roose, L.D.

    1996-04-23

    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. 13 figs.

  4. Measurement and analysis of solar cell current-voltage characteristics

    NASA Technical Reports Server (NTRS)

    Olsen, Larry C.; Addis, F. William; Doyle, Dan H.; Miller, Wesley A.

    1985-01-01

    Approaches to measurement and analysis of solar cell current-voltage characteristics under dark and illuminated conditions are discussed. Measurements are taken with a computer based data acquisition system for temperatures in the range of -100 to +100 C. In the fitting procedure, the various I(oi) and C(i) as well as R(S) and R(SH) are determined. Application to current-voltage analyses of high efficiency silicon cells and Boeing CdS/CuInSe2 are discussed. In silicon MINP cells, it is found that at low voltages a tunneling mechanism is dominant, while at larger voltages the I-V characteristics are usually dominated by emitter recombination. In the case of Boeing cells, a current transport model based on a tunneling mechanism and interface recombination acting in series has been developed as a result of I-V analyses.

  5. Measuring multimegavolt pulsed voltages using Compton-generated electrons

    Microsoft Academic Search

    S. B. Swanekamp; B. V. Weber; N. R. Pereira; D. D. Hinshelwood; S. J. Stephanakis; F. C. Young

    2004-01-01

    The “Compton–Hall” voltmeter is a radiation-based voltage diagnostic that has been developed to measure voltages on high-power (TW) pulsed generators. The instrument collimates photons generated from bremsstrahlung produced in the diode onto an aluminum target to generate Compton-generated electrons. Permanent magnets bend the Compton electron orbits that escape the target toward a silicon pin diode detector. A GaAs photoconductive detector

  6. Measuring multimegavolt pulsed voltages using Compton-generated electrons

    Microsoft Academic Search

    S. B. Swanekamp; B. V. Weber; N. R. Pereira; D. D. Hinshelwood; S. J. Stephanakis; F. C. Young

    2004-01-01

    The ``Compton-Hall'' voltmeter is a radiation-based voltage diagnostic that has been developed to measure voltages on high-power (TW) pulsed generators. The instrument collimates photons generated from bremsstrahlung produced in the diode onto an aluminum target to generate Compton-generated electrons. Permanent magnets bend the Compton electron orbits that escape the target toward a silicon pin diode detector. A GaAs photoconductive detector

  7. Open circuit voltage temperature coefficients vs. concentration: Theory, indoor measurements, and outdoor measurements

    NASA Astrophysics Data System (ADS)

    Bagienski, Will; Kinsey, Geoffrey S.; Liu, Mingguo; Nayak, Adi; Garboushian, Vahan

    2012-10-01

    Current-voltage characteristics of multijunction III-V solar cells from several different vendors were measured at different light concentrations and temperatures. Measurements were taken indoors using flash lamp solar simulators and outdoors under natural sunlight. The change in open-circuit voltage with temperature was measured. Modeled results, indoor measurements, and outdoor measurements are compared.

  8. A Thorax Simulator for Complex Dynamic Bioimpedance Measurements With Textile Electrodes.

    PubMed

    Ulbrich, Mark; Muhlsteff, Jens; Teichmann, Daniel; Leonhardt, Steffen; Walter, Marian

    2014-08-19

    Bioimpedance measurements on the human thorax are suitable for assessment of body composition or hemodynamic parameters, such as stroke volume; they are non-invasive, easy in application and inexpensive. When targeting personal healthcare scenarios, the technology can be integrated into textiles to increase ease, comfort and coverage of measurements. Bioimpedance is generally measured using two electrodes injecting low alternating currents (0.5-10 mA) and two additional electrodes to measure the corresponding voltage drop. The impedance is measured either spectroscopically (bioimpedance spectroscopy, BIS) between 5 kHz and 1 MHz or continuously at a fixed frequency around 100 kHz (impedance cardiography, ICG). A thorax simulator is being developed for testing and calibration of bioimpedance devices and other new developments. For the first time, it is possible to mimic the complete time-variant properties of the thorax during an impedance measurement. This includes the dynamic real part and dynamic imaginary part of the impedance with a peak-to-peak value of 0.2 ? and an adjustable base impedance (24.6 ? ? Z0 ? 51.6 ?) . Another novelty is adjustable complex electrode-skin contact impedances for up to 8 electrodes to evaluate bioimpedance devices in combination with textile electrodes. In addition, an electrocardiographic signal is provided for cardiographic measurements which is used in ICG devices. This provides the possibility to generate physiologic impedance changes, and in combination with an ECG, all parameters of interest such as stroke volume (SV), pre-ejection period (PEP) or extracellular resistance (Re) can be simulated. The speed of all dynamic signals can be altered. The simulator was successfully tested with commercially available BIS and ICG devices and the preset signals are measured with high correlation (r = 0.996). PMID:25148671

  9. State Estimation and Voltage Security Monitoring Using Synchronized Phasor Measurements

    Microsoft Academic Search

    Reynaldo Francisco Nuqui

    Abstract: The phasor measurement unit (PMU) is considered to be one of the most importantmeasuring devices in the future of power systems. The distinction comes from its uniqueability to provide synchronized phasor measurements of voltages and currents fromwidely dispersed locations in an electric power grid. The commercialization of the globalpositioning satellite (GPS) with accuracy of timing pulses in the order

  10. Gating behaviour of sodium currents in adult mouse muscle recorded with an improved two-electrode voltage clamp

    PubMed Central

    Fu, Yu; Struyk, Arie; Markin, Vladislav; Cannon, Stephen

    2011-01-01

    The availability of knock-in mutant mouse models for channelopathies of skeletal muscle has generated the need for improved methods to record ionic currents under voltage clamp in fully differentiated adult muscle fibres. A two-electrode voltage clamp has been optimized for recording Na+ currents in small fibres dissociated from the footpad. Clamp speed and spatial homogeneity were achieved by using short fibres (<600 ?m) that were detubulated with hyperosmolar glycerol. Series resistance errors were reduced by limiting current amplitude with low [Na+]. The quality of the voltage clamp was explored with computer simulations of a finite cable model with active conductances. Simulations quantitatively defined the range of conditions for which clamp control can be maintained, and provided estimates for the errors in the determination of gating parameters from standard pulse protocols. Sodium currents recorded from short fast-twitch muscles revealed a hyperpolarized shift in the voltage dependence of activation (V1/2?52 mV) and fast inactivation (V1/2?88 mV) compared to expression studies of NaV1.4 in mammalian cell lines. Slow inactivation occurred at depolarized potentials (V1/2?69 mV) relative to fast inactivation. These data reveal a marked divergence in the voltage dependence of fast and slow inactivation and provide normative values of Na+ channel behaviour for mouse skeletal muscle that will serve as a reference for the investigation of muscle ion channelopathies using genetically engineered mice or computer simulation. PMID:21135045

  11. 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

  12. Gated four-probe measurements on pentacene thin-film transistors: Contact resistance as a function of gate voltage and temperature

    Microsoft Academic Search

    Paul V. Pesavento; Reid J. Chesterfield; Christopher R. Newman; C. Daniel Frisbie

    2004-01-01

    We describe gated four-probe measurements designed to measure contact resistance in pentacene-based organic thin-film transistors (OTFTs). The devices consisted of metal source and drain electrodes contacting a 300-A˚-thick pentacene film thermally deposited on Al2O3 or SiO2 dielectrics with a p-doped Si substrate serving as the gate electrode. Voltage-sensing leads extending into the source-drain channel were used to monitor potentials in

  13. Control of threshold voltage in organic thin-film transistors by modifying gate electrode surface with MoOX aqueous solution and inverter circuit applications

    NASA Astrophysics Data System (ADS)

    Shiwaku, Rei; Yoshimura, Yudai; Takeda, Yasunori; Fukuda, Kenjiro; Kumaki, Daisuke; Tokito, Shizuo

    2015-02-01

    We controlled the threshold voltage of organic thin-film transistors (TFTs) by treating only the gate electrode surface with a MoOX aqueous solution and used them to build inverter circuits. The threshold voltage was changed by varying the concentration of the MoOX aqueous solution. A strong correlation between the work function of the gate electrode and the threshold voltage was observed. The threshold voltage of one of the two organic TFT devices in the inverter circuit was selectively changed by +2.3 V by reducing the concentration of the MoOx solution. We controlled the switching voltage of p-type organic inverter circuits and obtained excellent inverter characteristics. These results indicate that using a MoOx aqueous solution to control the threshold voltage is very useful for integrated circuits applications.

  14. Linearisation of ?DNA molecules by instantaneous variation of the trapping electrode voltage inside a micro-channel

    NASA Astrophysics Data System (ADS)

    Hanasaki, Itsuo; Yukimoto, Naoya; Uehara, Satoshi; Shintaku, Hirofumi; Kawano, Satoyuki

    2015-04-01

    Because long DNA molecules usually exist in random coil states due to the entropic effect, linearisation is required for devices equipped with nanopores where electrical sequencing is necessary during single-file translocation. We present a novel technique for linearising DNA molecules in a micro-channel. In our device, electrodes are embedded in the bottom surface of the channel. The application of a voltage induces the trapping of ?DNA molecules on the positive electrode. An instantaneous voltage drop is used to put the ?DNA molecules in a partly released state and the hydrodynamic force of the solution induces linearisation. Phenomena were directly observed using an optical microscopy system equipped with a high-speed camera and the linearisation principle was explored in detail. Furthermore, we estimate the tensile characteristics produced by the flow of the solution through a numerical model of a tethered polymer subject to a Poiseuille flow. The mean tensile force is in the range of 0.1–1 pN. This is sufficiently smaller than the structural transition point of ?DNA but counterbalances the entropic elasticity that causes the random coil shape of ?DNA molecules in solution. We show the important role of thermal fluctuation in the manipulation of molecules in solution and clarify the tensile conditions required for DNA linearisation using a combination of solution flow and voltage variation in a microchannel.

  15. Analysis of Firing Voltage in a Plasma Display Panel of Coplanar Electrodes

    NASA Astrophysics Data System (ADS)

    Cho, Guangsup; Kim, Young-Guon; Kim, Young-Sam; Joh, Dai-Geun; Choi, Eun-Ha

    1998-10-01

    The analytical solution of Laplace's equation with a symmetric potential profile has been obtained for investigating the breakdown criteria between the sustaining electrodes in the coplanar AC-type plasma display panel. Using this solution, Paschen's Law has been analyzed along the various discharge paths in the panel space using various sustaining electrode gap distances.

  16. Measurement of EMG activity with textile electrodes embedded into clothing

    Microsoft Academic Search

    T. Finni; M. Hu; P. Kettunen; T. Vilavuo; S. Cheng

    2007-01-01

    Novel textile electrodes that can be embedded into sports clothing to measure averaged rectified electromyography (EMG) have been developed for easy use in field tests and in clinical settings. The purpose of this study was to evaluate the validity, reliability and feasibility of this new product to measure averaged rectified EMG. The validity was tested by comparing the signals from

  17. Electric characteristics of a surface barrier discharge with a plasma induction electrode

    SciTech Connect

    Alemskii, I. N.; Lelevkin, V. M.; Tokarev, A. V.; Yudanov, V. A. [Kyrgyz-Russian Slavic University (Kyrgyzstan)

    2006-07-15

    Static and dynamic current-voltage and charge-voltage characteristics of a surface barrier discharge with a plasma induction electrode have been investigated experimentally. The dependences of the discharge current on both the gas pressure in the induction electrode tube and the winding pitch of the corona electrode, as well as of the discharge power efficiency on the applied voltage, have been measured.

  18. A HIGH CURRENT, HIGH VOLTAGE SOLID-STATE PULSE GENERATOR FOR THE NIF PLASMA ELECTRODE POCKELS CELL

    SciTech Connect

    Arnold, P A; Barbosa, F; Cook, E G; Hickman, B C; Akana, G L; Brooksby, C A

    2007-07-27

    A high current, high voltage, all solid-state pulse modulator has been developed for use in the Plasma Electrode Pockels Cell (PEPC) subsystem in the National Ignition Facility. The MOSFET-switched pulse generator, designed to be a more capable plug-in replacement for the thyratron-switched units currently deployed in NIF, offers unprecedented capabilities including burst-mode operation, pulse width agility and a steady-state pulse repetition frequency exceeding 1 Hz. Capable of delivering requisite fast risetime, 17 kV flattop pulses into a 6 {Omega} load, the pulser employs a modular architecture characteristic of the inductive adder technology, pioneered at LLNL for use in acceleration applications, which keeps primary voltages low (and well within the capabilities of existing FET technology), reduces fabrication costs and is amenable to rapid assembly and quick field repairs.

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

    PubMed

    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%. PMID:21034111

  20. Accurate voltage phasor measurement in a series-compensated network

    Microsoft Academic Search

    J. Lambert; D. McNabb; A. G. Phadke

    1994-01-01

    This paper describes the feasibility studies concerning an accurate voltage phasor measurement in series-compensated network undergoing large disturbances. The principal modes of distortions in such a network are described. Some of these modes are changing with the fundamental frequency. The phasor evaluation is based on a new digital filter approach in which the fundamental frequency is estimated using a least-square

  1. Progress in measurements with the ETF voltage balance

    Microsoft Academic Search

    Vojislav Bego; K. Poljancic; J. Butorac; G. Gasljevic

    1993-01-01

    The results of two series of measurements with the ETF-84 voltage balance carried out in 1987 and 1988, using the classical method of weighting, were previously presented by the authors (1988) with the proviso that some systematic errors had not been accounted for. Detailed analyses of these errors are not in progress, as are numerous experiments to determine the possible

  2. Electric and magnetic field measurements in a high voltage center

    Microsoft Academic Search

    A. S. Safigianni; A. I. Spyridopoulos; V. L. Kanas

    2011-01-01

    This paper investigates the electric and magnetic fields inside a high voltage center in Philippi, Greece, constituted both of 400\\/150 kV and 150\\/20 kV substation areas. Results of previous field measurements and calculations in substations are presented first. The basic data distinguishing the examined center from previously examined substations follow. The main results of the field measurements in the areas

  3. Measurement of pseudoephedrine hydrochloride dissolution using chloride-ion electrode.

    PubMed

    Chen, S T; Thompson, R C; Poust, R I

    1981-11-01

    Experiments were performed to determine the suitability of using a chloride-ion electrode for the measurement of pseudoephedrine hydrochloride dissolution from commercially available compressed tablets. Dissolution experiments were carried out in 500 ml of distilled water using the USP paddle method at 100 rpm. Both chloride ion and pseudoephedrine (UV spectrophotometry) were measured at six different sampling times. Percent dissolved versus time values were linearized on a log-normal probability basis. The slopes of individual lines obtained from the chloride and pseudoephedrine measurements were compared using a Student t test and did not differ significantly (t = 0.415, df = 5, p greater than 0.05). In addition to providing an efficient, inexpensive, and simple method for measuring pseudoephedrine hydrochloride dissolution rates, the chloride-ion electrode could be used in the measurement of dissolution rates for a wide variety of drugs available as hydrochloride salts. PMID:7299681

  4. Developing Barbed Microtip-Based Electrode Arrays for Biopotential Measurement

    PubMed Central

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

    2014-01-01

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

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

    SciTech Connect

    Mohanty, Debasish [ORNL; Li, Jianlin [ORNL; Abraham, Daniel P [Argonne National Laboratory (ANL); Huq, Ashfia [ORNL; Payzant, E Andrew [ORNL; Wood III, David L [ORNL; Daniel, Claus [ORNL

    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.

  6. Measuring skin conductivity --designed amplifier circuit to measure the voltage difference across two

    E-print Network

    Hero, Alfred O.

    Measuring skin conductivity -- designed amplifier circuit to measure the voltage difference across for skin conductivity and pulse rate signals (both in DC voltage) with sampling rate of 1kHz Algorithms -- Updating heart rate at each heart beat and determine the average of skin conductivity at the same time

  7. Concurrent Measurement of Thermopower and Current-Voltage Characteristics of Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Reddy, Pramod; Tan, Aaron; Sadat, Seid

    2010-03-01

    The Seebeck coefficient and the current-voltage characteristics of metal-molecule-metal junctions (MMMJs) are concurrently measured using a new atomic force microscope based technique. This enables the determination of the identity and the energetic separation of the molecular orbital that is closest to the Fermi level of the metal electrodes. Molecular junctions created by contacting a gold-coated atomic force microscope tip with four different self assembled monolayers (made from benzenethiol, dibenzenethiol, tribenzenethiol, tetrabenzenethiol) on gold substrates were found to have positive Seebeck coefficients ranging from 8 - 20 microvolts/K. The positive sign of the Seebeck coefficient unambiguously shows that charge transport in these junctions is dominated by the highest occupied molecular orbital (HOMO). Moreover, the Seebeck coefficient of the molecular junctions is found to increase monotonically with the length of molecular junctions. Further, by analyzing the current-voltage characteristics, the energetic separation of the HOMO level with respect to the Fermi level of the electrodes is also determined and is found to decrease with increasing lengths of the molecular junctions.

  8. Voltage-stability protection and control using a wide-area network of phasor measurements

    Microsoft Academic Search

    B. Milosevic; M. Begovic

    2003-01-01

    This paper presents a concept for local monitoring of the onset of voltage collapse, protective, and emergency control in the presence of voltage-sensitive loads. The onset of voltage collapse point is calculated based on the load characteristics and simulated voltage and current phasors measurements, which are provided by a network of phasor-measurement units. If the stability margin is small and

  9. Technical Development on Partial Discharge Measurement and Electrical Insulation Techniques for Low Voltage Motors Driven by Voltage Inverters

    Microsoft Academic Search

    Hitoshi Okubo; Naoki Hayakawa; Gian Carlo Montanari

    2007-01-01

    This paper reviews the up-to-date research activities on electrical insulation techniques under repetitive surge voltages with steep wavefront for low voltage inverter-fed motors. Partial discharge (PD) inception, propagation, ageing and breakdown characteristics of magnet wires, including recently developed PD-resistant wires such as nanocomposite enameled wires, are described. PD measurement techniques under the steep-front voltages and IEC activity toward their standardization

  10. Voltage Divider

    NSDL National Science Digital Library

    This voltage divider produces an output voltage, Vo, that is proportional to the input voltage, Vs. The output voltage is measured using a voltmeter. The input voltage is the voltage of the voltage source. The constant of proportionality is called the gain of the voltage divider. The value of the gain of the voltage divider is determined by the resistances, R1 and R2, of the two resistors that comprise the voltage divider.

  11. 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.

  12. Determination of the diagnostic x-ray tube practical peak voltage (PPV) from average or average peak voltage measurements.

    PubMed

    Hourdakis, C J

    2011-04-01

    The practical peak voltage (PPV) has been adopted as the reference measuring quantity for the x-ray tube voltage. However, the majority of commercial kV-meter models measure the average peak, ?(P), the average, ?, the effective, U(eff) or the maximum peak, U(P) tube voltage. This work proposed a method for determination of the PPV from measurements with a kV-meter that measures the average ? or the average peak, ?(p) voltage. The kV-meter reading can be converted to the PPV by applying appropriate calibration coefficients and conversion factors. The average peak k(PPV,kVp) and the average k(PPV,Uav) conversion factors were calculated from virtual voltage waveforms for conventional diagnostic radiology (50-150 kV) and mammography (22-35 kV) tube voltages and for voltage ripples from 0% to 100%. Regression equation and coefficients provide the appropriate conversion factors at any given tube voltage and ripple. The influence of voltage waveform irregularities, like 'spikes' and pulse amplitude variations, on the conversion factors was investigated and discussed. The proposed method and the conversion factors were tested using six commercial kV-meters at several x-ray units. The deviations between the reference and the calculated-according to the proposed method-PPV values were less than 2%. Practical aspects on the voltage ripple measurement were addressed and discussed. The proposed method provides a rigorous base to determine the PPV with kV-meters from ?(p) and ? measurement. Users can benefit, since all kV-meters, irrespective of their measuring quantity, can be used to determine the PPV, complying with the IEC standard requirements. PMID:21403184

  13. Single-Molecule Electronic Measurements with Metal Electrodes

    NASA Astrophysics Data System (ADS)

    Lindsay, Stuart

    2005-05-01

    The process of transferring electrons from one metal electrode to another via an intervening molecule differs from electrochemically or optically-induced electron transfer in important ways. The simplest process of ballistic electron transport with no charge localization on the molecule (tunneling) should be easy to understand quantitatively, yet experimental reports and theoretical calculations can differ by orders of magnitude. Here, we show how many of the discrepancies are resolved with measurements carefully constructed to provide data on single molecules connected to electrodes in well-defined ways. Furthermore, a number of these results are in good agreement with first-principles calculations (no adjustable parameters). The more interesting (and theoretically challenging) process of charge transport with intermediate localization by redox states can be measured in the same ways, but present theories do not yet describe these processes fully.

  14. Assessment of 129I measurement at low MV tandem voltages

    NASA Astrophysics Data System (ADS)

    Zhao, X.-L.; Litherland, A. E.; Kieser, W. E.; Soto, C.

    2007-06-01

    Significantly higher efficiencies for 129I measurement by Accelerator Mass Spectrometry (AMS) would be possible if 129I 3+ ions could be counted at terminal voltages as low as 1 MV. However, at M/ Q = 3, the molecular interference was anticipated to be severe; this has prevented the use of charge 3+ from being adequately considered. Instead, charge 5+ has been used at higher terminal voltages because of the minimal interference. During a recent performance assessment with charge state 3+, a background of 129I/ 127I ? 10 -14 was readily obtained and few 86Sr 2+ and 43Ca 1+ ions were encountered. This surprising result is possibly due to the very low binding energy and consequent poor stability of anions such as CaSr - and Ca3-. Some triply charged molecular ions were found in the energy spectrum at lower stripping gas pressure but their interference with the detection of 129I 3+ was readily suppressed with the Ar gas stripper operated at normal thickness. It now appears that as long as the prepared AMS samples are of good chemical purity, the molecular fragments can be expected to remain quite low in intensity and readily resolved by the final detector. As a result, charge state 3+ can be used for 129I measurements at lower terminal voltages with higher overall efficiency.

  15. Motion artifacts in capacitive ECG measurements: reducing the combined effect of DC voltages and capacitance changes using an injection signal.

    PubMed

    Serteyn, A; Vullings, R; Meftah, M; Bergmans, J W M

    2015-01-01

    Capacitive electrodes are a promising alternative to the conventional adhesive electrodes for ECG measurements. They provide more comfort to the patient when integrated in everyday objects (e.g., beds or seats) for long-term monitoring. However, the application of capacitive sensors is limited by their high sensitivity to motion artifacts. For example, motion at the body-electrode interface causes variations of the coupling capacitance which, in the presence of a dc voltage across the coupling capacitor, create strong artifacts in the measurements. The origin, relevance, and reduction of this specific and important type of artifacts are studied here. An injection signal is exploited to track the variations of the coupling capacitance in real time. This information is then used by an identification scheme to estimate the artifacts and subtract them from the measurements. The method was evaluated in simulations, lab environments, and in a real-life recording on an adult's chest. For the type of artifact under study, a strong artifact reduction ranging from 40 dB for simulated data to 9 dB for a given real-life recording was achieved. The proposed method is automated, does not require any knowledge about the measurement system parameters, and provides an online estimate for the dc voltage across the coupling capacitor. PMID:25137720

  16. Molds and Resists Studies for Nanoimprint Lithography of Electrodes in Low-Voltage Polymer Thin-Film Transistors

    NASA Astrophysics Data System (ADS)

    Cavallari, Marco Roberto; Zanchin, Vinicius Ramos; Pojar, Mariana; Seabra, Antonio Carlos; de Assumpção Pereira-da-Silva, Marcelo; Fonseca, Fernando Josepetti; de Andrade, Adnei Melges

    2014-05-01

    A low-cost patterning of electrodes was investigated looking forward to replacing conventional photolithography for the processing of low-operating voltage polymeric thin-film transistors. Hard silicon, etched by sulfur hexafluoride and oxygen gas mixture, and flexible polydimethylsiloxane imprinting molds were studied through atomic force microscopy (AFM) and field emission gun scanning electron microscopy. The higher the concentration of oxygen in reactive ion etching, the lower the etch rate, sidewall angle, and surface roughness. A concentration around 30 % at 100 mTorr, 65 W and 70 sccm was demonstrated as adequate for submicrometric channels, presenting a reduced etch rate of 176 nm/min. Imprinting with positive photoresist AZ1518 was compared to negative SU-8 2002 by optical microscopy and AFM. Conformal results were obtained only with the last resist by hot embossing at 120 °C and 1 kgf/cm2 for 2 min, followed by a 10 min post-baking at 100 °C. The patterning procedure was applied to define gold source and drain electrodes on oxide-covered substrates to produce bottom-gate bottom-contact transistors. Poly(3-hexylthiophene) (P3HT) devices were processed on high-? titanium oxynitride (TiO x N y ) deposited by radiofrequency magnetron sputtering over indium tin oxide-covered glass to achieve low-voltage operation. Hole mobility on micrometric imprinted channels may approach amorphous silicon (˜0.01 cm2/V s) and, since these devices operated at less than 5 V, they are not only suitable for electronic applications but also as sensors in aqueous media.

  17. Low drive voltage modulators with ultra low loss serpentine electrodes for electric field sensing with optical fibers

    Microsoft Academic Search

    James H. Cole; Marta M. Howerton; Robert P. Moeller; John Niemel; L. Cundin; C. Sunderman

    2005-01-01

    A key analog fiber-optic link parameter for RF and microwave antenna remoting is conversion gain or loss, which is a measure of the output RF power to the input RF power at the modulator. The link conversion loss can be minimized by using high-power lasers, modulators with low drive voltages, and sensitive photodetectors. It is highly desirable to achieve link

  18. Electrooptic matched filter controlled by independent voltages applied to multiple sets of electrodes

    E-print Network

    Kim, Changdong

    2006-04-12

    of the structure compensates for the difference between the two propagation constants. Assuming the phase-matching condition at a certain wavelength ? ? TM conversion becomes [12] 0.8FWHM L ???????? (50) where FWHM is the 3-dB bandwidth (FWHM... V3 V4 V5 V6 V7 V8 ? ? ? ? ? ? ? ? ? ? ? LiNbO3 Ti:LiNbO3 lc lp? ? 26 Fig. 12. Selection of voltages in the structure of a single sideband...

  19. Measurement of Thermopower and Current-Voltage Characteristics of Molecular Junctions to Identify Orbital Alignment

    SciTech Connect

    Tan, Aaron; Sadat, Seid; Reddy, Pramod

    2010-01-01

    We report an experimental technique that concurrently measures the Seebeck coefficient and the current-voltage (I-V) characteristics of a molecular junction to determine the identity and the effective energetic separation of the molecular orbital closest to the electrodes’ Fermi level. Junctions created by contacting a gold-coated atomic force microscope tip with a monolayer of molecules assembled on a gold substrate were found to have a Seebeck coefficient of (+16.9±1.4) ?V/K. This positive value unambiguously shows that the highest occupied molecular orbital (HOMO) dominates charge transport. Further, by analyzing the (I-V) characteristics, the HOMO level is estimated to be ? 0.69?eV with respect to the Fermi level.

  20. Electrooptic matched filter controlled by independent voltages applied to multiple sets of electrodes 

    E-print Network

    Kim, Changdong

    2006-04-12

    ()sy and integrate with respect to x. From the orthogonality between modes given by 2 s ms yy smExExdx ?? ? ? ? ?? =? with 1sm =? if sm and 0sm = otherwise, the following expression is derived: 2 () () 2.. [ (,)] ( )2 r ssjt z jt z s pert y... V3 V4 V5 V6 V7 V8 ? ? ? ? ? ? ? ? ? ? ? LiNbO3 Ti:LiNbO3 lc lp? ? 26 Fig. 12. Selection of voltages in the structure of a single sideband...

  1. Permittivity measurements using adjustable microscale electrode gaps between millimeter-sized spherical electrodes

    E-print Network

    Ma, Hongshen

    the electrical permittivity of liquids and gases using millimeter-sized spherical electrodes with adjustable microscale separation. This technique eliminates the need for wet calibration by using the precise adjustment of electrode separation to remove the inherent errors of parasitic capacitance and electrode polarization

  2. 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 ...

  3. Low consistency of four brain connectivity measures derived from intracranial electrode measurements.

    PubMed

    Jones, Stephen E; Beall, Erik B; Najm, Imad; Sakaie, Ken E; Phillips, Michael D; Zhang, Myron; Gonzalez-Martinez, Jorge A

    2014-01-01

    Measures of brain connectivity are currently subject to intense scientific and clinical interest. Multiple measures are available, each with advantages and disadvantages. Here, we study epilepsy patients with intracranial electrodes, and compare four different measures of connectivity. Perhaps the most direct measure derives from intracranial electrodes; however, this is invasive and spatial coverage is incomplete. These electrodes can be actively stimulated to trigger electrophysical responses to provide the first measure of connectivity. A second measure is the recent development of simultaneous BOLD fMRI and intracranial electrode stimulation. The resulting BOLD maps form a measure of effective connectivity. A third measure uses low frequency BOLD fluctuations measured by MRI, with functional connectivity defined as the temporal correlation coefficient between their BOLD waveforms. A fourth measure is structural, derived from diffusion MRI, with connectivity defined as an integrated diffusivity measure along a connecting pathway. This method addresses the difficult requirement to measure connectivity between any two points in the brain, reflecting the relatively arbitrary location of the surgical placement of intracranial electrodes. Using a group of eight epilepsy patients with intracranial electrodes, the connectivity from one method is compared to another method using all paired data points that are in common, yielding an overall correlation coefficient. This method is performed for all six paired-comparisons between the four methods. While these show statistically significant correlations, the magnitudes of the correlation are relatively modest (r (2) between 0.20 and 0.001). In summary, there are many pairs of points in the brain that correlate well using one measure yet correlate poorly using another measure. These experimental findings present a complicated picture regarding the measure or meaning of brain connectivity. PMID:25566178

  4. Nonlinear Impedance of Whole Cells Near an Electrode as a Probe of Mitochondrial Activity

    PubMed Central

    Palanisami, Akilan; Mercier, George T.; Fang, Jie; Miller, John H.

    2011-01-01

    By simultaneously measuring the bulk media and electrode interface voltages of a yeast (Saccharomyces cerevisiae) suspension subjected to an AC voltage, a yeast-dependent nonlinear response was found only near the current injection electrodes. Computer simulation of yeast near a current injection electrode found an enhanced voltage drop across the yeast near the electrode due to slowed charging of the electrode interfacial capacitance. This voltage drop is sufficient to induce conformation change in membrane proteins. Disruption of the mitochondrial electron transport chain is found to significantly change the measured nonlinear current response, suggesting nonlinear impedance can be used as a non-invasive probe of cellular metabolic activity. PMID:25586827

  5. Calibration of a Kerr Cell System for High-Voltage Pulse Measurements

    Microsoft Academic Search

    Esther Christmas Cassidy; Harold N. Cones; Donald C. Wunsch; Stanley R. Booker

    1968-01-01

    Several techniques for calibration of an electrooptical (Kerr cell) high-voltage pulse measuring system are described. Independent calibrations, without reference to pulse divider measurements, are achieved by application of a direct bias voltage to the Kerr cell. After calibration, experiments with voltages as high as 100 kV demonstrate reasonable agreement (to within 1 percent) between simultaneous Kerr cell and calibrated pulse

  6. Pockels cell voltage probe for noninvasive electron-beam measurements

    SciTech Connect

    Brubaker, Michael A. [Los Alamos National Laboratory, Group DX-8, Mail Stop P939, Los Alamos, New Mexico 87545 (United States); Yakymyshyn, Christopher P. [Montana State University, 610 Cobleigh Hall, Bozeman, Montana 59717-3780 (United States)

    2000-03-01

    Accurate measurements of beam position and current are critical for the operation of the high-energy electron accelerators used for radiographic applications. Traditional short-pulse (e.g., 70 ns) machines utilize B-dot loops to monitor these parameters with great success. For long-pulse (e.g, 2 {mu}s) accelerators, beam position and current measurements become more challenging and may require new technology. A novel electro-optic voltage probe has been developed for this application and provides the advantages of complete galvanic isolation, excellent low-frequency performance, and no time integration requirement. The design of a prototype sensor is presented along with preliminary accelerator test data. (c) 2000 Optical Society of America.

  7. Measuring electrode arrangement for grounding resistance measurement of grounding system in vertical-layered soil

    Microsoft Academic Search

    Rong Zeng; Jinliang He; Yanqing Gao; Weimin Sun; Qi Su

    2000-01-01

    How to precisely measure the grounding resistance of a substation is the fundamental factor to guarantee the safe operation of power system. The arrangement rules of measuring electrodes for the grounding resistance measurement of grounding system in vertical-layered soil were analyzed by numerical method. The demanded correct site for the potential rod under different directions is obtained when the grounding

  8. 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…

  9. 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.

  10. Power quality measurements performed on a low-voltage grid equipped with two wind turbines

    Microsoft Academic Search

    T. Thiringer

    1996-01-01

    The power quality of a low-voltage grid with two wind turbines is investigated. Slow voltage variations as well as transients and harmonics are measured and analysed. Furthermore, the spectrum of the power is determined so that the presence of periodic power components can be investigated. Although periodic power fluctuations reaching 10% of the rated power are registered, voltage variations are

  11. Power quality analysis based on fuzzy estimation algorithm: Voltage flicker measurements

    Microsoft Academic Search

    A. M. Al-Kandari; S. A. Soliman; R. A. Alammari

    2006-01-01

    This paper presents a method based on fuzzy linear estimation for voltage flicker measurements. The proposed algorithm uses the digitized samples of the voltage signal at the location where the power quality standards are implemented. The voltage signal is modeled as a fuzzy linear parameter estimation problem, where the coefficients are assumed to be fuzzy having certain middle and spread.

  12. Origin of Different Dependences of Open-Circuit Voltage on the Electrodes in Layered and Bulk Heterojunction Organic Photovoltaic Cells

    Microsoft Academic Search

    Chunfu Zhang; Shi-Wun Tong; Chang-Yun Jiang; En-Tang Kang; Daniel S. H. Chan; Chunxiang Zhu

    2010-01-01

    Experimental results show that the V OC of layered heterojunction (HJ) organic photovoltaic (PV) cells behaves with a very weak dependence on the electrodes. However, the V OC of bulk HJ PV cells behaves with a strong dependence on the electrodes. In this paper, an explanation for the different behaviors of V OC on the electrodes is proposed. It is

  13. Use of local measurements to estimate voltage-stability margin

    Microsoft Academic Search

    Khoi Vu; Miroslav M. Begovic; Damir Novosel; Murari Mohan Saha

    1999-01-01

    Estimating the proximity of power systems to voltage collapse in real time still faces difficulties. Beside the data management and computational issues, any central control method is subject to the reliability of long-distance data communications. In the paper, the authors describe a new data processing method to estimate the proximity to voltage collapse. The method (code-named SMARTDevice, for Stability Monitoring

  14. Impedance and ellipsometer measurements of lithium electrodes in propylene carbonate solutions

    SciTech Connect

    Schwager, F.; Muller, R.H.

    1983-09-01

    Complex electrode impedance has been measured for lithium after exposure to nitrogen, propylene carbonate and LiClO/sub 4/ solutions in propylene carbonate. Results for zero-field exchange current density and polarization resistance are in agreement with earlier current pulse measurements. Ellipsometer measurements show a different electrode behavior for anodic and cathodic reactions in perchlorate solution.

  15. Serial lead impedance measurements confirm fixation of helical screw electrodes during pacemaker implantation.

    PubMed

    Roelke, M; Bernstein, A D; Parsonnet, V

    2000-04-01

    The purpose of this study was to determine whether serial measurements of helical screw pacemaker lead impedance could reliably confirm electrode fixation in the right atrium and right ventricle. Fixation is generally assessed fluoroscopically, which can be misleading because the myocardium is radiolucent. Alternatively, because the electrical conductivity of blood is greater than that of myocardium, serial measurements of the lead impedance might be expected to show an impedance increase with appropriate fixation of the pacemaker electrode when the electrode becomes embedded in myocardial tissue. Impedance measurements were made during the placement of 23 atrial and 28 ventricular active fixation electrodes in 31 consecutive patients. Impedance measurements were recorded in unipolar and bipolar electrode configurations with the electrode free floating in the chamber, unfixed (with exposed screws) but touching the endocardial surface, and after fixation. No significant impedance differences were found between free-floating and unfixed electrode positions. With fixation, the lead impedance increased significantly in the ventricle (P = 0.0001, unipolar and bipolar) and the atrium (P = 0.0069 unipolar and 0.0052 bipolar). Typical increases, reflected by median values, were 197 ohms unipolar and 203 ohms bipolar in the ventricle and 47 ohms unipolar and 53 ohms bipolar in the atrium for electrodes with permanently exposed or retractable screw designs. Comparing serial measurements of lead impedance before and after electrode fixation is a valid electrical method of confirming appropriate fixation of helical screw electrodes. PMID:10793439

  16. The use of virtual ground to control transmembrane voltages and measure bilayer currents in serial arrays of droplet interface bilayers

    NASA Astrophysics Data System (ADS)

    Sarles, Stephen A.

    2013-09-01

    The droplet interface bilayer (DIB) is a simple technique for constructing a stable lipid bilayer at the interface of two lipid-encased water droplets submerged in oil. Networks of DIBs formed by connecting more than two droplets constitute a new form of modular biomolecular smart material, where the transduction properties of a single lipid bilayer can affect the actions performed at other interface bilayers in the network via diffusion through the aqueous environments of shared droplet connections. The passive electrical properties of a lipid bilayer and the arrangement of droplets that determine the paths for transport in the network require specific electrical control to stimulate and interrogate each bilayer. Here, we explore the use of virtual ground for electrodes inserted into specific droplets in the network and employ a multichannel patch clamp amplifier to characterize bilayer formation and ion-channel activity in a serial DIB array. Analysis of serial connections of DIBs is discussed to understand how assigning electrode connections to the measurement device can be used to measure activity across all lipid membranes within a network. Serial arrays of DIBs are assembled using the regulated attachment method within a multi-compartment flexible substrate, and wire-type electrodes inserted into each droplet compartment of the substrate enable the application of voltage and measurement of current in each droplet in the array.

  17. Voltage dependent capacitance -- a measure of energy level bending in naphthalene-tetra-carboxylic- di-imide based transistors

    NASA Astrophysics Data System (ADS)

    Nyman, Mathias; Sandberg, Oskar; Martinez Hardigree, Josue; Kola, Srinivas; Katz, Howard; Osterbacka, Ronald

    2013-03-01

    We demonstrate transient capacitance measurements using charge extraction by a linearly increasing voltage (CELIV) on the small molecule naphthalene-tetra-carboxylic- di-imide (NTCDI) based organic transistors. The OFETs use Aluminum (Al) and Aluminum Oxide (AlOx) as bottom gate and dielectric, with gold (Au) source and drain electrodes. The Al/AlOx gate is modified using two different self assembled monolayers, triethoxy(octyl)silane and perfluorooctyltriethoxysilane, in order to tune the turn-on voltage. We have clarified the voltage dependent capacitance in diode structures and found that when the transistor is in the fully on state a charge reservoir is formed at the AlOx interface and a saturation of the steady-state capacitance is seen, equaling the capacitance of the AlOx layer. When the transistor is in the fully off state the steady state capacitance saturates to the capacitance of the semiconductor bulk. We interpret this as a build-up of a charge reservoir in the semi conductor bulk when going from the off to the on state making it possible to charge the AlOx capacitance. By going from the on state towards the off state using a linearly increasing voltage pulse the dynamics of the depletion of the reservoir gives information about the energy level bending in the bulk.

  18. Sensitivity of performance and degradation measurements on AMTEC electrodes in sodium exposure test cells to experiment conditions

    Microsoft Academic Search

    Michael Schuller; B. Fiebig; Patricia Hudson; Alicia Williams

    2000-01-01

    In this paper we discuss performance and degradation measurements made on AMTEC electrodes in sodium exposure test cells. We measured electrode temperatures, sodium pool temperatures, and apparent charge transfer resistance values, from which we derived normalized exchange current density (B) values for WRh, MoRe, Re, and Ir electrodes. Electrode temperatures ranged from 600°C to 900°C, while sodium pool temperatures ranged

  19. A new gate current extraction technique for measurement of on-state breakdown voltage in HEMTs

    Microsoft Academic Search

    Mark H. Somerville; Roxann Blanchard; J. A. del Alamo; G. Duh; P. C. Chao

    1998-01-01

    We present a new simple three-terminal technique for measuring the on-state breakdown voltage in HEMTs. The gate current extraction technique involves grounding the source, and extracting a constant current from the gate. The drain current is then ramped from the off-state to the on-state, and the locus of drain voltage is measured. This locus of drain current versus drain voltage

  20. A New Geometric Factor for In Situ Resistivity Measurement Using Four Slender Cylindrical Electrodes

    Microsoft Academic Search

    Chee-Earn Chong; Yoke-Lin Tan

    2008-01-01

    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

  1. A New Method for Measurement of Bioelectrical Impedance

    Microsoft Academic Search

    Padma Batra; Sukhwinder Singh; Rahul Pratap Singh

    2011-01-01

    The paper describes the theory and practical implementation of a four-electrode method for measuring complex bioimpedance of local tissue. This new method adopts three independent voltages Vin+ ,Vin-, VR respectively from the two voltage electrodes and a sample resistor R, which is connected in serial with one of the two voltage electrodes. Theoretical analysis shows that real part Zreal and

  2. 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

  3. The effect of bias voltage on the measurement of local barrier height

    Microsoft Academic Search

    M. Yoshitake; S. Yagyu

    2003-01-01

    In this paper a relation among tunnel current, bias voltage and tip-specimen separation is examined based on Simmons' formula under constant LBH assumption. It has the been shown that to understand the effect of bias voltage on LBH, measurement has to be carried out under constant tip-specimen separation, not under constant tunnel current as normally used. Measuring local barrier height

  4. Comparison of the division ratios measured on different high voltage pulse calibration systems

    SciTech Connect

    Solomon, O.

    1998-04-01

    Both resistive and capacitive divider standards are used to measure pulse voltages with microsecond risetimes and amplitudes of hundreds of kilovolts. The dividers are composed entirely of passive components and should exhibit relatively constant impedance as a function of frequency, risetime and voltage. To the extent that this is not the case, these factors increase the uncertainty of the divider ratio. This paper presents a statistical comparison of the ratios of several voltage dividers using different high voltage pulse generators to gain insight as to the influence of the design of the divider and characteristics of the generator on the measurements.

  5. Choice of electrode geometry for accurate measurement of organic photovoltaic cell performance

    Microsoft Academic Search

    Myung-Su Kim; Myung-Gyu Kang; L. Jay. Guo; Jinsang Kim

    2008-01-01

    The relationship between the performance and the electrode geometry of organic photovoltaic devices was investigated to establish the proper electrode geometry for reproducible and accurate performance measurement. Photovoltaic cells (ITO\\/PEDOT:PSS\\/P3HT+PCBM\\/LiF\\/Al) having crossbar-type and island-type electrode geometries were fabricated. The crossbar-type cells varied greatly in performance depending on the illuminated light beam size relative to the overlap area of the crossbar-type

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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.

  7. 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. [Department of Experimental Physics, Comenius University, Mlynskadolina F2, 84248 Bratislava (Slovakia); Radjenovi?, B.; Radmilovi?-Radjenovi?, M. [Institute of Physics, University of Belgrade, P.O. Box 57, 11080 Belgrade (Serbia)

    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.

  8. Development and Demonstration of Measurement-Time Efficient Methods for Impedance Spectroscopy of Electrode and Sensor Arrays

    PubMed Central

    Cooper, Kevin R.; Smith, Matthew; Johnson, Derek

    2008-01-01

    The development of impedance-based array devices is hindered by a lack of robust platforms and methods upon which to evaluate and interrogate sensors. One aspect to be addressed is the development of measurement-time efficient techniques for broadband impedance spectroscopy of large electrode arrays. The objective of this work was to substantially increase the low frequency impedance measurement throughput capability of a large channel count array analyzer by developing true parallel measurement methods. The goal was achieved by Fourier transform-based analysis of simultaneously-acquired multi-channel time-based current and voltage data. Efficacy and quantitative analysis of the parallel approach at frequencies less than ca. 10 Hz as well as a combined sequential + parallel approach for efficient broadband impedance spectroscopy over 5-orders of magnitude in frequency is demonstrated through complex impedance measurement of arrays consisting of up to 100 elements.

  9. 3D visualization of subdural electrode shift as measured at craniotomy reopening

    PubMed Central

    LaViolette, Peter S.; Rand, Scott D.; Ellingson, Benjamin M.; Raghavan, Manoj; Lewd, Sean M.; Schmaindaa, Kathleen M.; Muellerd, Wade

    2015-01-01

    Summary Purpose Subdural electrodes are implanted for recording intracranial EEG (iEEG) in cases of medically refractory epilepsy as a means to locate cortical regions of seizure onset amenable to surgical resection. Without the aid of imaging-derived 3D electrode models for surgical planning, surgeons have relied on electrodes remaining stationary from the time between placement and follow-up resection. This study quantifies electrode shift with respect to the cortical surface occurring between electrode placement and subsequent reopening. Methods CT and structural MRI data were gathered following electrode placement on 10 patients undergoing surgical epilepsy treatment. MRI data were used to create patient specific post-grid 3D reconstructions of cortex, while CT data were co-registered to the MRI and thresholded to reveal electrodes only. At the time of resective surgery, the craniotomy was reopened and electrode positions were determined using intraoperative navigational equipment. Changes in position were then calculated between CT coordinates and intraoperative electrode coordinates. Results Five out of ten patients showed statistically significant overall magnitude differences in electrode positions (mean: 7.2 mm), while 4 exhibited significant decompression based shift (mean: 4.7 mm), and 3 showed significant shear displacement along the surface of the brain (mean: 7.1 mm). Discussion Shift in electrode position with respect to the cortical surface has never been precisely measured. We show that in 50% of our cases statistically significant shift occurred. These observations demonstrate the potential utility of complimenting electrode position measures at the reopening of the craniotomy with 3D electrode and brain surface models derived from post-implantation CT and MR imaging for better definition of surgical boundaries. PMID:21334178

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 cm3, 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.

  11. Simultaneous measurement of current and voltage by use of one bismuth germanate crystal.

    PubMed

    Li, Changsheng; Yoshino, Toshihiko

    2002-09-01

    An optical fiber sensor is presented that allows current and voltage to be measured simultaneously by use of only one block of bismuth germanate crystal. The polarized light from the sensing crystal is split into two light beams: One beam is utilized for current measurement based on the Faraday effect, and the other one is utilized for voltage measurement based on the Pockels effect. Compared with the existing optical sensors that can measure current and voltage simultaneously, this sensor is simple and inexpensive and allows measurement of electric power. The simultaneous measurements of ac electric current from 0.05 to 10 A, voltage from 1 to 235 V, and power from 2 to 1000 W have been achieved with good linear-response characteristics. The input characteristics and measurement uncertainties that are due to the nonlinear error of the sensing system are also discussed. PMID:12211569

  12. Novel active comb-shaped dry electrode for EEG measurement in hairy site.

    PubMed

    Huang, Yan-Jun; Wu, Chung-Yu; Wong, Alice May-Kuen; Lin, Bor-Shyh

    2015-01-01

    Electroencephalography (EEG) is an important biopotential, and has been widely applied in clinical applications. The conventional EEG electrode with conductive gels is usually used for measuring EEG. However, the use of conductive gel also encounters with the issue of drying and hardening. Recently, many dry EEG electrodes based on different conductive materials and techniques were proposed to solve the previous issue. However, measuring EEG in the hairy site is still a difficult challenge. In this study, a novel active comb-shaped dry electrode was proposed to measure EEG in hairy site. Different form other comb-shaped or spike-shaped dry electrodes, it can provide more excellent performance of avoiding the signal attenuation, phase distortion, and the reduction of common mode rejection ratio. Even under walking motion, it can effectively acquire EEG in hairy site. Finally, the experiments for alpha rhythm and steady-state visually evoked potential were also tested to validate the proposed electrode. PMID:25137719

  13. Voltage-dependent Membrane Displacements Measured by Atomic Force Microscopy

    PubMed Central

    Mosbacher, J.; Langer, M.; Hörber, J.K.H.; Sachs, F.

    1998-01-01

    Cells use polar molecules in the membrane to sense changes in the transmembrane potential. The opening of voltage-gated ion channels and membrane bending due to the inverse flexoelectric effect are two examples of such electromechanical coupling. We have looked for membrane motions in an electric field using atomic (or scanning) force microscopy (AFM) with the intent of studying voltage-dependent conformational changes of ion channels. Voltage-clamped HEK293 cells were either untransfected controls or transfected with Shaker K+ channels. Using a ± 10-mV peak–peak AC carrier stimulus, untransfected cells moved 0.5–15 nm normal to the plane of the membrane. These movements tracked the voltage at frequencies >1 kHz with a phase lead of 60–120°, as expected of a displacement current. The movement was outward with depolarization, but the holding potential only weakly influenced the amplitude of the movement. In contrast, cells transfected with a noninactivating mutant of Shaker K+channels showed similar movements, but these were sensitive to the holding potential; decreasing with depolarization between ?80 and 0 mV. Searching for artifactual origins of these movements, we used open or sealed pipettes and AFM cantilever placements just above the cells. These results were negative, suggesting that the observed movements were produced by the cell membrane rather than by movement of the patch pipette, or by acoustic or electrical interactions of the membrane with the AFM tip. In control cells, the electrical motor may arise from the flexoelectric effect, where changes in potential induce changes in curvature. In transfected cells, it appears that channel-specific movements also occurred. These experiments demonstrate that the AFM may be able to exploit voltage-dependent movements as a source of contrast for imaging membrane components. The electrically induced motility will cause twitching during action potentials, and may have physiological consequences. PMID:9417135

  14. On the design of capacitive sensors using flexible electrodes for multipurpose measurements

    Microsoft Academic Search

    Pierre Thibault; Pantxo Diribarne; Thierry Fournier; Sylvain Perraud; Laurent Puech; P.-Etienne Wolf; Bernard Rousset; Roser Vallcorba

    2007-01-01

    This article evaluates the potential of capacitive measurements using flexible electrodes to access various physical quantities. These electrodes are made of a thin metallic film, typical thickness 0.2 mum, evaporated on a plastic substrate. Their large flexibility enables them to be mounted in complex geometries such as curved surfaces. In the configuration of planar condensers, using a very sensitive commercial

  15. 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

  16. 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.

  17. Rotor position sensing in switched reluctance motor drives by measuring mutually induced voltages

    Microsoft Academic Search

    Iqbal Husain; Mehrdad Ehsani

    1994-01-01

    This paper describes a new method of indirect rotor position sensing for switched reluctance motor (SRM) drives. The principle is based on measuring the mutually induced voltage in an inactive phase which is either adjacent or opposite to the energized phase of an SRM. The mutual voltage in the “off” phase, induced due to the current in the active phase,

  18. Transient-boundary voltage method for measurement of equivalent circuit components of rechargeable batteries

    Microsoft Academic Search

    K. H. Norian

    A method is presented for measuring the equivalent circuit components of rechargeable batteries. The temporal discharge–rest–charge–rest sequence of a rechargeable battery is described, using the principles of transient circuit analysis, to derive equations for the battery voltage as a function of time during voltage transients and at the boundaries at transitions between transient phases. The equations lead to a new

  19. Probe for measurements of the DC electric field in air around high voltage apparatus

    Microsoft Academic Search

    K. Johansson; L. Walfridsson; U. Ga?fvert; B. Ka?llstrand; S. Ho?rnfeldt

    2010-01-01

    Knowledge of the external field distribution around high voltage apparatus is of vital importance. As a part of the effort to improve the physical understanding of the DC field distribution outside high voltage apparatus, a small probe that can measure DC electric fields has been developed and a first version of this probe has been tested. The probe is 26

  20. Measurement of bias voltage dependence of local barrier height at constant tip-sample separation

    Microsoft Academic Search

    Shinjiro Yagyu; Michiko Yoshitake

    2003-01-01

    We measured the bias voltage dependence of the apparent local barrier height (LBH) by STM on an Au (111) surface with an Au tip. The results under two different conditions, a constant tip-sample separation and a constant current, were compared in the low bias voltage range (?30 to ?5 mV). Under constant separation, the LBH does not change with the

  1. Kalman filter based high speed measurement and control of AC voltages for UPS applications

    Microsoft Academic Search

    Seshadri Sivakumar; K. Natarajan

    1993-01-01

    A scheme is proposed for high speed measurement and processing of AC voltages encountered in offline uninterruptible power supplies (UPSs) based on the design of a Kalman filter with an internal model of the sinusoidal waveform. The proposed scheme provides a common framework to monitor the UPS mains input supply, to sense its out-of-specification voltage and frequency conditions, and to

  2. Realization of the kilogram by measuring at 100 kV with the voltage balance ETF

    Microsoft Academic Search

    Vojislav Bego; Josip Butorac; D. Ilic

    1999-01-01

    The possibilities for adapting the existing electrostatic device known as the voltage balance ETF-84, to work with a voltage of 100 kV and a weight of 1 kg, are considered. A few theoretical analyses, experiments, and computer simulations have been carried out to define the measurement procedure needed at the required level of uncertainty of 1 part in 108. These

  3. Probe measurements in a discharge with liquid nonmetallic electrodes in air at atmospheric pressure

    Microsoft Academic Search

    Yu. A. Barinov; S. M. Shkol’nik

    2002-01-01

    Discharges with liquid nonmetallic electrodes of much interest for applications are investigated. It is found that a dc discharge\\u000a between two streams of tap water in air at atmospheric pressure is stable at a currentof 40?I?100 mA. The discharge exists in the diffuse (volume) form with a relatively low current density (?0.2 A\\/cm2) and a high (above one kilovolt) voltage

  4. [Effect of increase and decrease of measurement voltage on skin impedance].

    PubMed

    Wu, B; Hu, X; Xu, J

    1993-01-01

    The skin impedance has been used as an index to plot out the meridian courses. In most of this kind of methods during measurement voltage was necessary to deliver to the subject's skin. It is unknown whether increasing the measuring voltage can change non-low skin impedance points (non-LSIP) into low skin impedance points (LSIP). In order to clarify the problem, we made an investigation on the effect of increasing and decreasing the measuring voltage on skin impedance. Subjects under observation were 12 healthy volunteers. On the medial side of forearm two levels were selected for measurement. Four or twenty non-LISP were observed on each level. The measuring system worked on the basis of bioelectrode method. The measurement and data processing were controlled by microcomputer. During measurement impedance of LSIP decreased correspondingly with the increase of voltage and vice versa, but the value of impedance was not exceeded 100k omega in spite of increasing or decreasing the voltage. That is, low impedance is the inherent characteristics of LSIP. On the contrary, the impedance of non-LSIP remained in higher than 600k omega in most of cases during increasing voltage from 10 to 50v. As the voltage increased to 65v, the impedance in a part of non-LSIP decreased to such a low level as LSIP. However, their impedance increased rapidly to high level again once the measuring voltage decreased. The above results reveal that the response of non-LSIPs and LSIPs were different from each other in nature. Increasing the voltage could not change a non-LSIP into LSIP.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8070036

  5. Studying the Performance of Conductive Polymer Films as Textile Electrodes for Electrical Bioimpedance Measurements

    NASA Astrophysics Data System (ADS)

    Cunico, F. J.; Marquez, J. C.; Hilke, H.; Skrifvars, M.; Seoane, F.

    2013-04-01

    With the goal of finding novel biocompatible materials suitable to replace silver in the manufacturing of textile electrodes for medical applications of electrical bioimpedance spectroscopy, three different polymeric materials have been investigated. Films have been prepared from different polymeric materials and custom bracelets have been confectioned with them. Tetrapolar total right side electrical bioimpedance spectroscopy (EBIS) measurements have been performed with polymer and with standard gel electrodes. The performance of the polymer films was compared against the performance of the gel electrodes. The results indicated that only the polypropylene 1380 could produce EBIS measurements but remarkably tainted with high frequency artefacts. The influence of the electrode mismatch, stray capacitances and large electrode polarization impedance are unclear and they need to be clarified with further studies. If sensorized garments could be made with such biocompatible polymeric materials the burden of considering textrodes class III devices could be avoided.

  6. Design for manufacture of a micro-interdigitated electrode for impedance measurement in a biochemical assay

    NASA Astrophysics Data System (ADS)

    Donoghue, Linda; Anthony, Brian W.

    2012-03-01

    The performance of interdigitated electrodes for impedance measurements in a microfluidic assay chamber is dependent upon the geometric design of the electrode pattern and can be significantly impacted by variability or defects in manufacturing or materials. For processes which rely on precise electrode performance, it is necessary to minimize variation through robust design and quality control. An interdigitated electrode design was investigated to identify design strategies which maximize electrode sensitivity and minimize performance variability in produced parts, while potentially reducing the complexity of quality testing. Several configurations were developed to address these goals by increasing the sensing region for a specified electrode area and creating designs which can be easily manufactured with low variability. Design modifications included alterations to interdigitated finger orientation, finger geometry, and gap width. Test findings indicate that optimal designs contain narrow gap widths with electrode fingers parallel to the longest dimension of the electrode. These benefits may be further enhanced by replacing straight finger edges with geometrical features, such as scalloped edges. The design changes identified can be used to improve interdigitated electrode performance for an array of applications and to reduce performance variability caused by variation in the manufacturing process.

  7. 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. [Blackett Laboratory, Imperial College, London SW7 2BW (United Kingdom)

    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.

  8. Measurement of high voltage using Rutherford backscattering spectrometry 

    E-print Network

    Abrego, Celestino Pete

    2007-04-25

    the particles on high-voltage plates.1) The Texas A&M University prototype will utilize the K500 superconducting cyclotron to direct a beam of singly charged helium ions to the collector of the prototype which is predicted to achieve electric potentials... accelerator capable of producing ions with energies up to 150 keV was used during this research. The ions used in this experiment were singly charged helium atoms. This section will give a brief overview of the mechanisms responsible for producing an ion...

  9. Preliminary kerr electro-optic field mapping measurements in propylene carbonate using point-plane electrodes

    Microsoft Academic Search

    T. J. Gung; A. Üstundag; M. Zahn

    1999-01-01

    Propylene carbonate is used in Kerr electro-optic field mapping measurements because of its non-toxic chemical nature and very high Kerr constant. We describe the experimental design and chemical purification procedure that minimizes reactions with the electrodes and removes particles and moisture. We measure the optical characteristic parameters using the ac modulation method with point-plane electrodes that allows calculation of the

  10. A DSP based real time power quality measurement system with voltage distortion improvement capability

    E-print Network

    Gou, Jian

    1992-01-01

    A DSP BASED REAL TIME POWER QUALITY MEASUREMENT SYSTEM WITH VOLTAGE DISTORTION IMPROVEMENT CAPABILITY A Thesis by JIAN GOU Submitted to the Office of Graduate Studies oi' Texas ARM University m partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1992 Major Subject: Electrical Engineering A DSP BASED REAL TIME POWER QUALITY MEASUREMENT SYSTEM WITH VOLTAGE DISTORTION IMPROVEMENT CAPABILITY A Thesis by JIAN GOU Approved as to style and content by: P...

  11. A DSP based real time power quality measurement system with voltage distortion improvement capability 

    E-print Network

    Gou, Jian

    1992-01-01

    A DSP BASED REAL TIME POWER QUALITY MEASUREMENT SYSTEM WITH VOLTAGE DISTORTION IMPROVEMENT CAPABILITY A Thesis by JIAN GOU Submitted to the Office of Graduate Studies oi' Texas ARM University m partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August 1992 Major Subject: Electrical Engineering A DSP BASED REAL TIME POWER QUALITY MEASUREMENT SYSTEM WITH VOLTAGE DISTORTION IMPROVEMENT CAPABILITY A Thesis by JIAN GOU Approved as to style and content by: P...

  12. Selection of the Optimum Electrospray Voltage for Gradient Elution LC-MS Measurements

    PubMed Central

    Marginean, Ioan; Kelly, Ryan T.; Moore, Ronald J.; Prior, David C.; LaMarche, Brian L.; Tang, Keqi; Smith, Richard D.

    2009-01-01

    Changes in liquid composition during gradient elution liquid chromatography (LC) coupled to mass spectrometry (MS) analyses affect the electrospray operation. To establish methodologies for judicious selection of the electrospray voltage, we monitored in real-time the effect of the LC gradient on the spray current. The optimum range of the electrospray voltage decreased as the concentration of organic solvent in the eluent increased during reversed-phase LC analyses. These results provided the means to rationally select the voltage so as to ensure effective electrospray operation throughout gradient-elution LC separations. For analyses in which the electrospray was operated at constant voltage, a small run-to-run variation in the spray current was observed, indicating a changing electric field due to fouling or degradation of the emitter. Algorithms using feedback from spray current measurements to maintain the electrospray voltage within the optimum operating range throughout gradient elution LC-MS were evaluated. The electrospray operation with voltage regulation and at a constant, judiciously selected voltage during gradient elution LC-MS measurements produced data with similar reproducibility. SYNOPSIS Electrospray current measurements during gradient elution liquid chromatography analyses provide reliable feedback for monitoring, understanding, and improving performance. PMID:19196520

  13. Real-time measurements of corticosteroids in conscious animals using an antibody-based electrode.

    PubMed

    Cook, C J

    1997-05-01

    An electrochemical immunosensor for real-time determination of corticosteroids, a group of steroidal hormones, is reported. The sensor measures competitive binding of endogenous corticosteroid and a corticosteroid-peroxidase conjugate with antibodies, immobilized on a platinum electrode, by monitoring of peroxidase activity. The electrode is encased within a dialysate membrane, which separates the electrode environment from the sampled fluid, allowing corticosteroid to equilibrate across the membrane. This permits measurements to be made in vivo. The small size of the probe (350 microns D) allows implantation into tissue or circulatory systems. The electrode was viable for 200 to 400 sequential measurements and at least 48 h in vivo. Detection sensitivity is 0.2 to 0.6 microgram/100 ml of cortisol or corticosterone. The results suggest the possibility of monitoring hormones in real-time within the blood or organ systems of conscious animals. PMID:9131628

  14. Needle Enzyme Electrode for Lactate Measurement In Vivo

    Microsoft Academic Search

    Zimei Rong; Eugenia Leitao; Jonathan Popplewell; BurÇak Alp; Pankaj Vadgama

    2008-01-01

    Electrochemical lactate needle enzyme electrodes were fabricated based on lactate oxidase with a conventional hydrogen peroxide detection regimen with a linear range up to 7 mM, response time ~ 3 min, and sensitivity ~ 1 nA\\/mM. A negatively charged inner (sulphonated polyether ether sulphone-polyether sulphone) membrane was applied for ensuring selectivity by limiting oxidazible anion diffusion to the Pt working

  15. 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.

  16. 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.

  17. Results from 3-D silicon sensors with wall electrodes: near-cell-edge sensitivity measurements as a preview of active-edge sensors

    Microsoft Academic Search

    Christopher J. Kenney; Sherwood Parker; Edith Walckiers

    2001-01-01

    Silicon sensors with a three-dimensional (3-D) architecture, in which the n and p electrodes penetrate through the entire substrate, have been successfully fabricated. The electrode spacing can be less than the substrate thickness, allowing short collection paths, low depletion voltages, and large current signals from rapid charge collection. This paper gives results when the cylindrical electrodes of the earlier papers

  18. Luminous flux improvement of xenon fluorescent lamps by applying synchronized high-voltage pulse to the auxiliary external electrode

    Microsoft Academic Search

    Hideki Motomura; Kojiro Oka; Toru Sogabe; Masafumi Jinno

    2011-01-01

    As the environmental awareness of people becomes stronger, the demand for mercury-free light sources also becomes stronger. The authors have been developing cold cathode fluorescent lamps in which xenon gas is filled as an ultraviolet radiator instead of mercury. Previously the authors reported the luminous flux enhancement method using a grounded auxiliary external electrode (AEE). In this paper, in order

  19. 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.

  20. Measurement of 2-5 MV pulsed-voltages in electron beam diodes from Compton generated electrons

    Microsoft Academic Search

    S. B. Swanekamp; R. J. Commisso; B. V. Weber; F. C. Young

    2002-01-01

    Summary form only given, as follows. Measuring multi-megavolt voltages across pulsed electron-beam diodes is very difficult. A capacitive probe can measure the voltage in the water or oil transmission line feeding power to the diode. However, this is usually far electrically from the diode and an inductive correction is usually applied to obtain the diode voltage. The two main problems

  1. Detection of DNA hybridization and extension reactions by an extended-gate field-effect transistor: Characterizations of immobilized DNA–probes and role of applying a superimposed high-frequency voltage onto a reference electrode

    Microsoft Academic Search

    Masao Kamahori; Yu Ishige; Maki Shimoda

    2008-01-01

    As we have already shown in a previous publication [Kamahori, M., Ihige, Y., Shimoda, M., 2007. Anal. Sci. 23, 75–79], an extended-gate field-effect transistor (FET) sensor with a gold electrode, on which both DNA probes and 6-hydroxyl-1-hexanethiol (6-HHT) molecules are immobilized, can detect DNA hybridization and extension reactions by applying a superimposed high-frequency voltage to a reference electrode. However, kinetic

  2. Fault Location for Single-Circuit Line Based on Bus-Impedance Matrix Utilizing Voltage Measurements

    Microsoft Academic Search

    Yuan Liao

    2008-01-01

    Diverse transmission line fault location algorithms have been proposed in the past depending on measurements available. Existing algorithms usually require measurements captured from buses of a faulted line. By taking advantage of the bus-impedance matrix technique, this paper presents a possible fault location approach for single-circuit lines utilizing only voltage measurements from one or two buses, which may be distant

  3. Experiment for measurements of the gas breakdown statistics by ramp voltage pulses

    SciTech Connect

    Markovic, V. Lj.; Stamenkovic, S. N.; Gocic, S. R.; Petrovic, Z. Lj. [Department of Physics, University of Nis, P.O. Box 224, 18001 Nis (Serbia and Montenegro); Institute of Physics, P.O. Box 68, 11080 Belgrade (Serbia and Montenegro)

    2006-09-15

    In the first part of this article the electronic automatic system for the measurements of dynamic breakdown voltages U{sub b} with linearly rising (ramp) pulses is presented. It generates the sequence of ramp pulses with subvoltage level U{sub sub}{approx_equal}0 during the relaxation time {tau} of the tube, and the ramp pulses start from the static breakdown voltage U{sub s}, thus enabling the correct study of electrical breakdowns and relaxation in gases. In the second part the measurements in argon with and without a voltage during the off period of the pulse are analyzed. The influence of the subvoltage on the mean value of the breakdown voltage U{sub b} as a function of the rise rate k, on the statistical U{sub b} distributions and on the afterglow kinetics is also discussed.

  4. Enhancement of digital equivalent voltage flicker measurement via continuous wavelet transform

    Microsoft Academic Search

    Shyh-Jier Huang; Chen-Wen Lu

    2004-01-01

    In this paper, a continuous wavelet transform-based approach is proposed to assist the measurement of voltage flicker. With the time-frequency localization characteristics embedded in wavelets, the time and frequency information of a waveform is seen integrally presented, thereby enhancing the monitoring capability of voltage flicker signals at different time intervals. By embodying the Gaussian wavelet function, this proposed wavelet-direct demodulation

  5. Electrode oxygen-affinity influence on voltage nonlinearities in high-k metal-insulator-metal capacitors

    E-print Network

    Paris-Sud XI, Université de

    -insulator-metal capacitors C. Vallée, P. Gonon, C. Jorel, and F. El Kamel Citation: Appl. Phys. Lett. 96, 233504 (2010); doi-insulator-metal capacitors C. Vallée,1,a P. Gonon,1 C. Jorel,1 and F. El Kamel2 1 Microelectronics Technology Laboratory (LTM-insulator-metal capacitors. Several metallic electrodes are tested in order to investigate the role of the metal work

  6. "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.

  7. Electrochemical impedance measurement of prostate cancer cells using carbon nanotube array electrodes in a microfluidic channel

    NASA Astrophysics Data System (ADS)

    Heung Yun, Yeo; Dong, Zhongyun; Shanov, Vesselin N.; Schulz, Mark J.

    2007-11-01

    Highly aligned multi-wall carbon nanotubes were synthesized in the shape of towers and embedded into fluidic channels as electrodes for impedance measurement of LNCaP human prostate cancer cells. Tower electrodes up to 8 mm high were grown and easily peeled off a silicon substrate. The nanotube electrodes were then successfully soldered onto patterned printed circuit boards and cast into epoxy under pressure. After polishing the top of the tower electrodes, RF plasma was used to enhance the electrocatalytic effect by removing excess epoxy and activating the open end of the nanotubes. Electrodeposition of Au particles on the plasma-treated tower electrodes was done at a controlled density. Finally, the nanotube electrodes were embedded into a polydimethylsiloxane (PDMS) channel and electrochemical impedance spectroscopy was carried out with different conditions. Preliminary electrochemical impedance spectroscopy results using deionized water, buffer solution, and LNCaP prostate cancer cells showed that nanotube electrodes can distinguish the different solutions and could be used in future cell-based biosensor development.

  8. Effect of current compliance and voltage sweep rate on the resistive switching of HfO2/ITO/Invar structure as measured by conductive atomic force microscopy

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    The electrical characterization of HfO2/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 HfO2 surface, such that it acted as the top electrode. Nanoscale current-voltage (I-V) characteristics of the HfO2/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.

  9. A miniature all-solid-state calcium electrode applied to in situ seawater measurement

    NASA Astrophysics Data System (ADS)

    Xu, Hui; Wang, You; Luo, Zhiyuan; Pan, Yiwen

    2013-12-01

    An all-solid-state miniature calcium ion selective electrode (ISE) based on poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT(PSS)) for continuous in situ measurement in seawater was studied. The electrode substrate was a platinum (Pt) wire of 0.5 mm diameter and PEDOT(PSS) was electropolymerized on one end of the Pt wire to act as the solid contact of this calcium ISE. The PEDOT(PSS) layer was covered with a calcium-selective poly(vinyl chloride) membrane, which contained ETH129 as calcium ionophore, potassium tetrakis-(p-chlorophenyl)borate as lipophilic anion and bis(2-ethylhexyl) sebacate as the plasticizer. Experiments using electrochemical impedance spectroscopy and reversed chronopotentiometry illustrated that electropolymerized PEDOT(PSS) decreased the resistance and improved the stability of the electrode. The sensors can work stably in the calcium ion concentration range of 10-6-10-1 mol L-1 with the slope of 27.7 mV/decade. Also Na+, K+ and Mg2+ can hardly interfere with the performance of the electrode. This electrode was applied to measure the calcium ion concentration of seawater samples. The experimental data showed that the electrode can resist the corrosion of seawater and its reproducibility was good (SD < 0.1 mM kg-1). The lifetime of such an electrode was at least six months. Because of the wire-shape and the small size of such a liquid junction free calcium electrode, it is pressure-resistant and easy to package and seal, therefore it is suitable for use in underwater equipment for in situ seawater measurement.

  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. On the design of capacitive sensors using flexible electrodes for multipurpose measurements

    NASA Astrophysics Data System (ADS)

    Thibault, Pierre; Diribarne, Pantxo; Fournier, Thierry; Perraud, Sylvain; Puech, Laurent; Wolf, P.-Etienne; Rousset, Bernard; Vallcorba, Roser

    2007-04-01

    This article evaluates the potential of capacitive measurements using flexible electrodes to access various physical quantities. These electrodes are made of a thin metallic film, typical thickness 0.2 ?m, evaporated on a plastic substrate. Their large flexibility enables them to be mounted in complex geometries such as curved surfaces. In the configuration of planar condensers, using a very sensitive commercial capacitive bridge and a three-terminal measurement method, several measurements are presented. A relative resolution of 10-8 for the thermal expansion of samples is obtained at low temperature in a differential configuration. The same technique adopted for pressure gauge measurements at low temperature led to a typical 0.1 Pa resolution over a dynamic range of 104 Pa. In the configuration of interleaved electrodes, condensers have been used to measure wetting by either bulk liquid helium or by thin continuous helium films in a cylindrical pipe. Both experimental and numerical evidence is provided, showing that the close proximity of a reference ground potential significantly increases the relative sensitivity to fluid wetting. Further, interleaved electrodes can be used to access both the area that is covered by a liquid film but also to determine the thickness of this film, provided it is comparable to the periodicity of the electrode pattern.

  12. Iridium Oxide Nanotube Electrodes for Highly Sensitive and Prolonged Intracellular Measurement of Action Potentials

    PubMed Central

    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 made up of 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 center. We show that this geometry enhances cell-electrode coupling and results in measuring much larger intracellular action potentials. The nanotube electrodes 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 electrode performance can be significantly improved by optimizing the electrode geometry. PMID:24487777

  13. The Coefficient of the Voltage Induced Frequency Shift Measurement on a Quartz Tuning Fork

    PubMed Central

    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

  14. Measurement and communication techniques for remote condition monitoring of high voltage transformer bushings

    Microsoft Academic Search

    D. Cornforth; G. Ledwich

    1998-01-01

    The insulation used in high voltage transformer bushings experiences an aging process, which reduces its effectiveness and ultimately may lead to catastrophic breakdown. The progress of aging can be estimated by measuring various parameters of the insulator material. The most easily obtainable parameters are electrical, and this fact has led to the introduction of commercial automated measurement systems suitable for

  15. Neuro-fuzzy networks for voltage security monitoring based on synchronized phasor measurements

    Microsoft Academic Search

    Chih-Wen Liu; Chen-Sung Chang; Mu-Chun Su

    1998-01-01

    The ability to rapidly acquire synchronized phasor measurements from around a power network opens up new possibilities for power system operation and control. A novel neuro-fuzzy network, the fuzzy hyperrectangular composite neural network, is proposed for voltage security monitoring (VSM) using synchronized phasor measurements as input patterns. This paper demonstrates how neuro-fuzzy networks can be constructed offline and then utilized

  16. Characteristics and measurement of capacitor switching at medium voltage distribution level

    Microsoft Academic Search

    C. E. McCoy; B. L. Floryancic

    1993-01-01

    Capacitors are used extensively in power systems for power factor improvement. There are occasions when capacitor bank switching on or offline is required. The main\\/basic characteristics and impact that capacitors and capacitor switching cause on medium voltage plant distribution systems are discussed. Analytical information and the results of actual measurement are included. The measurement equipment used also provides harmonic spectrum

  17. Matrix converter commutation strategies with and without explicit input voltage sign measurement

    Microsoft Academic Search

    Jochen Mahlein; Jens Igney; Jörg Weigold; Michael Braun; Olaf Simon

    2002-01-01

    This paper gives an overview to voltage-controlled matrix converter commutation. Conventional converter systems with explicit sign measurement circuits that were necessary for the commutation in the past are discussed. New operation methods eliminating these extra measuring circuits are presented. The paper explains the new methods. Advantages and disadvantages of different approaches are discussed. The robustness of the new methods against

  18. 18650 Li-ion cells with reference electrode and in situ characterization of electrodes

    NASA Astrophysics Data System (ADS)

    Nagasubramanian, G.; Doughty, D. H.

    At Sandia National Laboratories, we have built 18650 Li-ion cells with Li reference electrode for in situ characterization of electrodes including impedance and other electrochemical properties. At a 200 mA (˜C/5 rate) discharge, the cell gave ˜900 mAh. Impedance measurements indicate that the anode dominates the cell impedance. For example, at 0 °C, the anode and cathode impedances at 10 mHz were around 149 and 53 m?, respectively, and the total cell impedance at 10 mHz was ˜203 m?. The three-electrode configuration also permits measurement of individual electrode voltages during charge and discharge. During discharge, while the cell voltage drops from 4.1 to 3 V, the cathode and the anode voltages change from 4.1 to 3.7 and from ˜0 to 0.7 V, respectively. During charge, the cathode and anode voltages trace back to their initial values before discharging. The voltage swing for the anode is higher than that for the cathode. This also indicates that the impedance for the anode is higher than for the cathode. Pulse measurements on the cells indicate the voltage drop of the full-cell is equal to the sum of the anode and cathode voltage drops for a 2 A discharge pulse.

  19. Measurements of the Fracture Energy of Lithiated Silicon Electrodes of Li-Ion Batteries

    E-print Network

    Suo, Zhigang

    of the observed cracks appear brittle in nature. By determining the condition for crack initiation, the fractureMeasurements of the Fracture Energy of Lithiated Silicon Electrodes of Li-Ion Batteries Matt Pharr, Cambridge, Massachusetts 02138, United States ABSTRACT: We have measured the fracture energy of lithiated

  20. 1 Measurements of the Fracture Energy of Lithiated Silicon Electrodes 2 of Li-Ion Batteries

    E-print Network

    . By determining the 15 condition for crack initiation, the fracture energy is calculated using an analysis from1 Measurements of the Fracture Energy of Lithiated Silicon Electrodes 2 of Li-Ion Batteries 3 Matt University, Cambridge, Massachusetts 02138, United States 5 ABSTRACT: We have measured the fracture energy

  1. High-resolution dc-voltage-biased ac conductance bridge for tunnel junction measurements

    Microsoft Academic Search

    M. V. Moody; J. L. Paterson; R. L. Ciali

    1979-01-01

    A simple, low-cost conductance bridge circuit, which provides high-resolution measurements of dI\\/dV and d2I\\/dV2 for a voltage-biased load, is presented. A resolution in dI\\/dV for a 90-Omega tunnel junction of several parts in 105 has been measured using a 35-muV-rms modulation level and a 1-s postdetection time constant (Bn=0.25 Hz). The output impedance of the voltage source and the error

  2. High-resolution dc-voltage-biased ac conductance bridge for tunnel junction measurements

    Microsoft Academic Search

    M. V. Moody; J. L. Paterson; R. L. Ciali

    1979-01-01

    A simple, low-cost conductance bridge circuit, which provides high-resolution measurements of dI\\/dV and d2I\\/dV2 for a voltage-biased load, is presented. A resolution in dI\\/dV for a 90-? tunnel junction of several parts in 105 has been measured using a 35-?V-rms modulation level and a 1-s postdetection time constant (Bn=0.25 Hz). The output impedance of the voltage source and the error

  3. 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.

  4. Real time measurement of current and voltage in discharge pumped KrF* excimer lasers

    NASA Astrophysics Data System (ADS)

    Onkels, E. D.; Seelig, W.

    1997-08-01

    An advanced measurement method for the dynamic current voltage characteristics of fast transversely excited atmosphere excimer laser discharges is presented. In contrast to well-known numerical techniques, inductive components are eliminated from the measured discharge gap voltage directly during operation of the laser by means of a fast video amplifier circuit. Comparison of experimental data obtained from a laboratory KrF* excimer laser with theoretical data shows that the achieved resolution is sufficiently high to reveal actual halogen donor concentration and arcing in the discharge.

  5. Partial discharge measurements on a high voltage direct current mass impregnated paper cable

    SciTech Connect

    Jeroense, M.J.P. [NKF KABEL B.V., Delft (Netherlands); Kreuger, F.H. [Delft Univ. of Technology (Netherlands)

    1996-12-31

    Partial discharge measurement has been a good tool for the quality assurance of cables under alternating voltage. With the growing interest in High Voltage Direct Current cables it seems therefore logical to extend this technique for use at direct voltage. The paper describes this technique as used on a HVDC cable with mass impregnated paper. The different phases of operation (no load, full load, cooling phase, etc.) are characterized by a different discharge behavior. Special attention is given to the dangerous cooling phase. Models have been developed which can explain the discharge patterns that were measured. This paper gives an insight in the electrical behavior of a HVDC cable with mass impregnated paper insulation.

  6. 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. .

  7. Evaluation of the catalytic performance of gas-evolving electrodes using local electrochemical noise measurements.

    PubMed

    Zeradjanin, Aleksandar R; Ventosa, Edgar; Bondarenko, Alexander S; Schuhmann, Wolfgang

    2012-10-01

    Characterization of gas evolution reactions at the electrode/electrolyte boundary is often difficult due to the dynamic behavior of interfacial processes. Electrochemical noise measurements determined by scanning electrochemical microscopy were used to characterize Cl(2) evolution at gas-evolving electrodes (GEEs). Analysis of the electrochemical noise is a powerful method to evaluate the efficiency of the catalyst layer at a GEE. The high sensitivity of the developed measurement system enabled accurate monitoring of the current fluctuations caused by gas-bubble detachment from the electrode surface. Fourier transform analysis of the obtained current responses allows extraction of the characteristic frequency, which is the main parameter of the macrokinetics of GEEs. The characteristic frequency was used as part of a methodology to evaluate the catalyst performance and, in particular, to estimate the fraction of the catalyst layer that is active during the gas evolution reaction. PMID:23001744

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

    SciTech Connect

    Kim, Yunseok [ORNL; Yang, J.-C. [University of California, Berkeley; Chu, Ying Hao [National Chiao Tung University, Hsinchu, Taiwan; Yu, Pu [University of California, Berkeley; Lu, X. [Xidian University, China; Jesse, Stephen [ORNL; Kalinin, Sergei V [ORNL

    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.

  9. Impedance studies of Ni/Cd and Ni/H2 cells using the cell case as a reference electrode

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1989-01-01

    Impedance measurements have been made on several Ni/Cd and Ni/H2 flightweight 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 voltages of the cell cases with respect to the individual electrodes differ from cell to cell even at the same overall cell voltage, but they remains 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.

  10. Faradic resistance of the electrode\\/electrolyte interface

    Microsoft Academic Search

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

    1992-01-01

    A new method is used to measure the direct-current (Faradic) resistance of a single electrode\\/electrolyte interface. The method\\u000a employs a constant-current pulse and a potential-sensing electrode. By choosing a sufficiently long pulse duration, the voltage\\u000a between the test and potential-sensing electrode exhibits a three-phase response. In the steady-state phase, the voltage measured\\u000a is equal to the current flowing through the

  11. Polyimide-based multi-channel arrayed electrode for measuring EEG signal on the skull of mouse.

    PubMed

    Baek, Dong-Hyun; Lee, Eun-Joong; Moon, Jin-Hee; Choi, Jee Hyun; Pak, James Jungho; Lee, Sang-Hoon

    2009-01-01

    In this paper, we have developed 40 channel multiple electrodes mounted on the surface of mouse's skull using polyimide substrate and tested its performance by measuring EEG signals. The recording site of the electrode was electroplated by Pt to enhance both contact impedance and adhesive strength by applying proper current, cleaning surface and removing H(2) gas bubbles. For in vivo test, the electrode was placed on the skull of F1 mouse and EEG signals were measured. We observed the suitability of electrode for measuring EEG signals from multiple areas on the skull. The spectrum of EEG signal to change was observed by urethane administration. PMID:19964191

  12. A Real-Time Voltage Instability Identification Algorithm Based on Local Phasor Measurements

    Microsoft Academic Search

    Sandro Corsi; Glauco N. Taranto

    2008-01-01

    This paper proposes a new voltage instability risk indicator based on local phasor measurements at fast sampling rate. The effectiveness of the indicator is analyzed at EHV load and ldquotransitrdquo buses. The risk criterion is based on the real-time computation of the Thevenin equivalent impedance of the classic electrical circuit given by an equivalent generator connected to an equivalent load

  13. Industrial installation for voltage-on space measurements in HVDC cables

    Microsoft Academic Search

    Jerome CASTELLON; S. Agnel; A. Toureille; J. Matallana; H. Janah; P. Mirebeau; D. Sy

    2005-01-01

    This work is concerned with a facility for characterizing the insulation of power cables whilst submitted to high dc voltage. The presented tool allows to measure the real distribution of the electric field in the cable insulation, which can be significantly different from the capacitive (Laplace) field repartition, and is of interest in insulation design and survey. After reviewing the

  14. Development of measuring techniques for high voltage impulse and small signals using Pockels cell

    Microsoft Academic Search

    J. Y. Koo; Y. M. Chang; J. Y. Hong; K. L. Cho; J. J. Song

    1994-01-01

    A recent increase in electric power demand requires stable power supply, which could be achieved by improving the diagnostic and preventive methods for the power apparatus. For this purpose, it is highly necessary to develop better measuring techniques for not only the fast transient impulse voltages but small signals. The former, coming into the substation, are produced by the overvoltages

  15. Improvement of a proposed model for heat conduction in an electrode submitted to an electric discharge: Application to the indirect determination of the anodic and cathodic voltage drops

    Microsoft Academic Search

    L. Benzerga; C. Lhiaubet; R. M. Meyer

    1985-01-01

    We present an improved version of a heat-conduction model which leads to better-computed values of the anodic voltage drops for electric discharges in a liquid dielectric, with a short interelectrode gap (about 50 ?m) and short duration (10–1000 ?s). The results obtained show monotonic variations according to the duration of the discharge and peak current, and correspond to the measured

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

    PubMed

    Kim, Minjae; Kim, Taewan; Kim, Dong Sung; Chung, Wan Kyun

    2015-01-01

    Surface electromyography is widely used in many fields to infer human intention. However, conventional electrodes are not appropriate for long-term measurements and are easily influenced by the environment, so the range of applications of sEMG is limited. In this paper, we propose a flexible band-integrated, curved microneedle array electrode for robust long-term measurements, high selectivity, and easy applicability. Signal quality, in terms of long-term usability and sensitivity to perspiration, was investigated. Its motion-discriminating performance was also evaluated. The results show that the proposed electrode is robust to perspiration and can maintain a high-quality measuring ability for over 8 h. The proposed electrode also has high selectivity for motion compared with a commercial wet electrode and dry electrode. PMID:26153773

  17. Biosensor based on an enzyme modified electrode for highly-sensitive measurement of polyphenols

    Microsoft Academic Search

    Arkadi Eremenko; Alexander Makower; Wen Jin; Petra Rüger; Frieder Scheller

    1995-01-01

    The use of glucose dehydrogenase from Acinetobacter calcoaceticus for highly sensitive measurement of polyphenols, based on bioelectrocatalytic analyte recycling, has been demonstrated. A polyphenol (analyte) is oxidized on the surface of a glassy carbon electrode at an anodic potential and is regenerated by immobilized glucose dehydrogenase (GDH) in the presence of glucose, resulting in an amplified response. The dynamic properties

  18. A study on electrode for amperometric measurement of human stress with flow injection analysis biosensing system

    Microsoft Academic Search

    Lee Yoot Khuan; M. Hurairah Adha b Kamaruddin; Mohd Firdaus Abdullah; N. K. Madzhi; Anuar Ahmad

    2010-01-01

    This paper presents a study on electrode for the amperometric detection of human stress based on salivary alpha amylase, emulated with different concentration of glucose, with the flow injection analysis biosensing system. Amperometric detection is an electrochemical voltammetric measurement approach, where the current intensity in a detection cell is regarded as a function of the concentration of the analyte. Flow

  19. Design and testing under actual condition of performance of an optical voltage measurement transformer for transmission lines electrical of high voltage

    NASA Astrophysics Data System (ADS)

    Gomez, Nicolas; Salazar, Hernan; Ciro, Alberto

    2013-11-01

    In this research paper briefly describes the design and construction of an optical voltage transducer measurement based on the effect electro - optical Pockels. The equipment is designed to operate in electric transmission lines 110 kV AC. It then describes the electrical tests performed on transformer to actual operating conditions. In the design and construction of the optical transformer used a photorefractive crystal Bi4Ge3O20 (BGO), which was used because of its high sensitivity to changes in the electric field as a light source is used a laser diode with a wavelength of 670 nm. Presents the results of performance tests on potential levels appropriate to the optical laboratory. In the second part of this work was subjected to optical transformer operating voltage levels of 110 kV ac in this test the voltage was applied gradually until the operating voltage. Team performance was satisfactory.

  20. Quantitative characterization of the spin-orbit torque using harmonic Hall voltage measurements

    NASA Astrophysics Data System (ADS)

    Hayashi, Masamitsu; Kim, Junyeon; Yamanouchi, Michihiko; Ohno, Hideo

    2014-04-01

    Solid understanding of current induced torques is a key to the development of current and voltage controlled magnetization dynamics in ultrathin magnetic heterostructures. To evaluate the size and direction of such torques, or effective fields, a number of methods have been employed. Here, we examine the adiabatic (low-frequency) harmonic Hall voltage measurement that has been used to study the effective field. We derive an analytical formula for the harmonic Hall voltages to evaluate the effective field for both out of plane and in-plane magnetized systems. The formula agrees with numerical calculations based on a macrospin model. Two different in-plane magnetized films, Pt|CoFeB|MgO and CuIr|CoFeB|MgO are studied using the formula developed. The effective field obtained for the latter system shows relatively good agreement with that estimated using spin torque switching phase diagram measurements reported previously. Our results illustrate the versatile applicability of harmonic Hall voltage measurement for studying current induced torques in magnetic heterostructures.

  1. Measurement of transmembrane potential and current in cardiac muscle: a new voltage clamp method.

    PubMed Central

    Goldman, Y; Morad, M

    1977-01-01

    1. A single sucrose gap voltage clamp technique was developed to correct for artifacts of 'leakage' corrent and extracellular resistance making possible improved measurement of membrane current and membrane potential in cardiac muscle. 2. A fourth compartment termed 'guard gap' was added to the sucrose gap. The guard gap is maintained at the same potential as the Reinger pool, so that no extracellular leakage current can flow into the Ringer pool. Comparison of experimental results with the predictions of an idealized cable model indicates that the guard gap is effective in trapping leakage current. 3. The slow charging of membrane capacitance due to extracellular series resistance was accelerated by applying a 'pre-pulse' of the command potential past the final voltage clamp value. 4. A second technique, termed 'chopped current pulse clamp', was used to compensate for the extracellular resistance throughout the voltage clamp step. The applied current was turned on and off at a frequency of 0-5-2 kHz. The membrane potential sampled during the zero current phase was fed back through the clamp loop. 5. With either of these compensation techniques, the voltage and current traces settle to effectively constant values within 2-4 msec after initiation of a hyperpolarizing voltage clamp step from rest. 6. The membrane conductance measured by the prepulse and chopped current-pulse technique are equal and confirm a higher conductance at rest than during the plateau of the action potential. 7. The 'instantaneous' current-voltage relation of the membrane is linear during the plateau of the frog ventricular action potential. PMID:301933

  2. Detection of bottom ferromagnetic electrode oxidation in magnetic tunnel junctions by magnetometry measurements

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Nam, Dao N. H.; Lu, Jiwei; Wolf, Stuart A.

    2010-12-01

    Surface oxidation of the bottom ferromagnetic (FM) electrode, one of the major detrimental factors to the performance of a magnetic tunnel junction (MTJ), is difficult to avoid during the fabrication process of the MTJ's tunnel barrier. Since Co rich alloys are commonly used for the FM electrodes in MTJs, overoxidation of the tunnel barrier results in the formation of a CoO antiferromagnetic (AF) interface layer which couples with the bottom FM electrode to form a typical AF/FM exchange bias (EB) system. In this work, surface oxidation of the CoFe and CoFeB bottom electrodes was detected via magnetometry measurements of EB characterizations including the EB field, training effect, uncompensated spin density, and enhanced coercivity. Variations in these parameters were found to be related to the surface oxidation of the bottom electrode, among them the change in coercivity is most sensitive. Annealed samples show evidence for an oxygen migration back to the MgO tunnel barrier by annealing.

  3. Band energies of nanoparticle semiconductor electrodes determined by spectroelectrochemical measurements of free electrons.

    PubMed

    Mandal, Dhritabrata; Hamann, Thomas W

    2015-05-01

    Nanostructured semiconductor electrodes have garnered intense recent interest for use in various solar energy conversion systems since they offer the possibilities of circumventing low efficiencies associated with short diffusion length bulk materials as well as optimizing light absorption in dye-sensitized solar cells. In such context, knowledge of the conduction (ECB) and valence band (EVB) edge positions are the most important electronic properties in order to optimize performance and obtain a detailed understanding of relevant electron-transfer processes. However, there is no reliable direct method to measure the band edges in nanostructured semiconductor electrodes. Spectroeletrochemical methods have been utilized, but the nature of the absorbing species and interpretation of results are unsettled issues. Herein we describe a new simple spectroelectrochemical method which simultaneously produces the conduction band energy and the extinction coefficient, ?, of free conduction band electrons in nanoparticle TiO2 electrodes. PMID:25864683

  4. A multi-electrode plane capacitive sensor for displacement measurements and attitude controls

    NASA Astrophysics Data System (ADS)

    Picotto, Gian Bartolo; Pisani, Marco; Sosso, Andrea

    2009-08-01

    A novel, multi-electrode capacitive sensor has been designed, realized and tested at INRiM (Istituto Nazionale di Ricerca Metrologica). The circular active electrode of a guarded plane-parallel capacitive sensor is sub-divided into four sectors of equal area. The four output signals from each independent sensor are acquired, normalized and summed, to obtain the displacement. Similarly, by a combination of summing and differencing, the tip and tilt between the relative electrodes can be determined. An angular sensitivity up to 70 mV µrad-1 with a noise level of approximately 85 µV Hz-1/2 has been achieved with a working distance of 50 µm. The angular sensitivity decreases to a few mV µrad-1 for plate separations larger than 200 µm. The measuring electronics was set for a full-scale displacement range of several hundreds of micrometers.

  5. Cooling of electrically insulated high voltage electrodes down to 30 mK Kühlung von elektrisch isolierten Hochspannungselektroden bis 30 mK

    E-print Network

    Eisel, Thomas; Bremer, J

    2011-01-01

    The Antimatter Experiment: Gravity, Interferometry, Spectroscopy (AEGIS) at the European Organization for Nuclear Research (CERN) is an experiment investigating the influence of earth’s gravitational force upon antimatter. To perform precise measurements the antimatter needs to be cooled to a temperature of 100 mK. This will be done in a Penning trap, formed by several electrodes, which are charged with several kV and have to be individually electrically insulated. The trap is thermally linked to a mixing chamber of a 3He-4He dilution refrigerator. Two link designs are examined, the Rod design and the Sandwich design. The Rod design electrically connects a single electrode with a heat exchanger, immersed in the helium of the mixing chamber, by a copper pin. An alumina ring and the helium electrically insulate the Rod design. The Sandwich uses an electrically insulating sapphire plate sandwiched between the electrode and the mixing chamber. Indium layers on the sapphire plate are applied to improve the ther...

  6. 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

  7. 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.

  8. 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.

  9. High-voltage coaxial switch

    SciTech Connect

    Rink, J.P.

    1981-06-03

    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 is described. 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.

  10. Design of electrode array for impedance measurement of lesions in arteries.

    PubMed

    Cho, Sungbo; Thielecke, Hagen

    2005-04-01

    Use of impedance catheters can provide additional information about the composition and the morphology of early plaques in arteries. However, for a correct interpretation of the impedance data recorded inside a vessel, the extra-vessel conditions should not influence the measurement results. In this paper, we estimate the influence of the extra-vessel conditions on the impedance measurement of a vessel wall by using FEM simulation and a two-layer model. Therefore sensitivity fields are simulated. The simulations are validated by experiments and compared to analytical solutions. Further, the influence of the inner radius of a vessel on the measurement result is determined by FEM simulations. From experiments based on the two-layer model, it is found that the apparent resistance depends on the thickness of the first layer and the separation distance of the electrode structure. The measured result corresponds to the results of the FEM simulations, whereas the analytical solution assuming point electrodes is different from the measurement and simulation results. Under the assumption of homogenous and linear volume conductors, the FEM simulated distributions of sensitivity fields are determined. The inner diameter of the artery has no influence on the measurement results. The FEM simulation can support the design of electrode configuration and geometries for impedance catheters. PMID:15798232

  11. Resting voltage measurements of the rabbit corneal endothelium using patch-current clamp techniques.

    PubMed

    Watsky, M A; Rae, J L

    1991-01-01

    The resting potential (Em) of freshly isolated rabbit corneal endothelium was measured at room temperature (22 degrees C) and at 34 degrees C. Due to the wide range of values reported in the literature and the difficulty in obtaining long-term measurements using microelectrodes in these cells, a current-clamp technique was employed using whole cell patch-clamp electrodes. The electrodes contained a K+ methanesulfonate-based intracellular solution, and a NaCl/HCO3- Ringer's solution was used extracellularly. Three preparations of endothelium were examined: single dissociated cells, the isolated monolayer (stripped from the stroma with Descemet's membrane), and the intact isolated cornea. The perforated-patch technique, with amphotericin B in the electrode, was also used with the intact-cornea preparation at 34 degrees C. The mean Em values for the combined preparations at 22 degrees C and 34 degrees C were -35.3 mV and -55.0 mV, respectively; those for the intact-cornea preparation were -34.4 mV and -61.6 mV (at 22 degrees C and 34 degrees C, respectively). The isolated monolayer preparation showed a small but significant depolarization at both temperatures. These results demonstrate temperature dependence for Em in the corneal endothelium and show that more extensively dissected preparations have similar although not identical Ems to those of the intact cornea. PMID:1987091

  12. Voltage-dependent gating and gating charge measurements in the Kv1.2 potassium channel.

    PubMed

    Ishida, Itzel G; Rangel-Yescas, Gisela E; Carrasco-Zanini, Julia; Islas, León D

    2015-04-01

    Much has been learned about the voltage sensors of ion channels since the x-ray structure of the mammalian voltage-gated potassium channel Kv1.2 was published in 2005. High resolution structural data of a Kv channel enabled the structural interpretation of numerous electrophysiological findings collected in various ion channels, most notably Shaker, and permitted the development of meticulous computational simulations of the activation mechanism. The fundamental premise for the structural interpretation of functional measurements from Shaker is that this channel and Kv1.2 have the same characteristics, such that correlation of data from both channels would be a trivial task. We tested these assumptions by measuring Kv1.2 voltage-dependent gating and charge per channel. We found that the Kv1.2 gating charge is near 10 elementary charges (eo), ?25% less than the well-established 13-14 eo in Shaker. Next, we neutralized positive residues in the Kv1.2 S4 transmembrane segment to investigate the cause of the reduction of the gating charge and found that, whereas replacing R1 with glutamine decreased voltage sensitivity to ?50% of the wild-type channel value, mutation of the subsequent arginines had a much smaller effect. These data are in marked contrast to the effects of charge neutralization in Shaker, where removal of the first four basic residues reduces the gating charge by roughly the same amount. In light of these differences, we propose that the voltage-sensing domains (VSDs) of Kv1.2 and Shaker might undergo the same physical movement, but the septum that separates the aqueous crevices in the VSD of Kv1.2 might be thicker than Shaker's, accounting for the smaller Kv1.2 gating charge. PMID:25779871

  13. IEEE TRANSACTIONS ON MAGNETICS, VOL. 43, NO. 6, JUNE 2007 2651 Driven-Voltage Permeability Variation Measurements

    E-print Network

    Paris-Sud XI, Université de

    The complex permeability variation measurements at microwave frequencies of a magnetostrictiveIEEE TRANSACTIONS ON MAGNETICS, VOL. 43, NO. 6, JUNE 2007 2651 Driven-Voltage Permeability Variation Measurements of Bilayered Magnetostrictive/Piezoelectric Materials &for Tunable Microwave

  14. Active medical implants and occupational safety--measurement and numerical calculation of interference voltage.

    PubMed

    Gustrau, F; Bahr, A; Goltz, S; Eggert, S

    2002-01-01

    Low frequency electric and magnetic fields may interfere with implanted cardiac pacemakers causing a life-threatening malfunction of the device. In order to assess the safety of workers in the vicinity of industrial electrical devices the interference voltage at the input port of a pacemaker is an important measure. In order to investigate the coupling of fields emanating from electrical devices a numerical method for the calculation of interference voltages is presented and applied to the investigation of homogeneous electric and magnetic fields in the frequency range from 50 Hz to 1 MHz. Implantation of the pacemaker in the right pectoral, left pectoral and abdominal area using a realistic model of the human body as well as different grounding conditions are considered. The numerical method is successfully validated by measurements and shows good agreement with results in the literature. PMID:12465266

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

    SciTech Connect

    Iskrenovi?, Predrag S.; Krsti?, Ivan B.; Obradovi?, Bratislav M., E-mail: obrat@ff.bg.ac.rs; Kuraica, Milorad M. [Faculty of Physics, University of Belgrade, 11000 Belgrade (Serbia)

    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. Note: Adhesive stamp electrodes using spider silk masks for electronic transport measurements of supra-micron sized samples

    NASA Astrophysics Data System (ADS)

    Steven, E.; Jobiliong, E.; Eugenio, P. M.; Brooks, J. S.

    2012-04-01

    A procedure for fabricating adhesive stamp electrodes based on gold coated adhesive tape used to measure electronic transport properties of supra-micron samples in the lateral range 10-100 ?m and thickness >1 ?m is described. The electrodes can be patterned with a ˜4 ?m separation by metal deposition through a mask using Nephila clavipes spider dragline silk fibers. Ohmic contact is made by adhesive lamination of a sample onto the patterned electrodes. The performance of the electrodes with temperature and magnetic field is demonstrated for the quasi-one-dimensional organic conductor (TMTSF)2PF6 and single crystal graphite, respectively.

  17. Note: adhesive stamp electrodes using spider silk masks for electronic transport measurements of supra-micron sized samples.

    PubMed

    Steven, E; Jobiliong, E; Eugenio, P M; Brooks, J S

    2012-04-01

    A procedure for fabricating adhesive stamp electrodes based on gold coated adhesive tape used to measure electronic transport properties of supra-micron samples in the lateral range 10-100 ?m and thickness >1 ?m is described. The electrodes can be patterned with a ~4 ?m separation by metal deposition through a mask using Nephila clavipes spider dragline silk fibers. Ohmic contact is made by adhesive lamination of a sample onto the patterned electrodes. The performance of the electrodes with temperature and magnetic field is demonstrated for the quasi-one-dimensional organic conductor (TMTSF)(2)PF(6) and single crystal graphite, respectively. PMID:22559592

  18. 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.

  19. Optical transmission of thermal measurements from high voltage devices in high vacuum conditions

    Microsoft Academic Search

    M Brombin; M Boldrin; M Dalla Palma; R Ghiraldelli; F Molon; N Pomaro; G Serianni; R Pasqualotto

    2011-01-01

    matteo.brombin@i gi.cnr.it Abstract-The paper describes a system for digitization and optical transmission of thermal measurements on high voltage devices in high vacuum environmental conditions and presents the tests conducted on a prototype. The system has been designed in particular to satisfy such technical requirements as to be mounted on the grounded grid of the SPIDER facility (a lOOkeV\\/60A particle accelerator)

  20. Parametric analysis of aSi solar cells from current voltage measurements

    Microsoft Academic Search

    S. S. Hegedus; J. E. Phillips

    1994-01-01

    A procedure is presented for accurately representing the current voltage (JV) characteristic of a-Si solar cells. The measured JV data is separated into the forward diode current and photocurrent. The forward diode current is characterized to obtain standard diode parameters A, J 0, and R. The AM1.5 photocurrent JL(V) is characterized using the uniform field model to determine the ratio

  1. A new approach to high-speed flow measurements using constant voltage anemometry

    NASA Technical Reports Server (NTRS)

    Mangalam, S. M.; Sarma, G. R.; Kuppa, S.; Kubendran, L. R.

    1992-01-01

    The paper addresses the basic features of conventional instrumentation, such as the constant temperature (CTA) and the constant current (CCA) anemometers, their limitations, and describes a totally new approach to high-speed dynamic measurements using a constant voltage anemometer (CVA). The paper describes the design features of a newly developed CVA and compares preliminary results obtained with CVA and conventional anemometry in low- and high-speed flows.

  2. Drilling electrode for real-time measurement of electrical impedance in bone tissues.

    PubMed

    Dai, Yu; Xue, Yuan; Zhang, Jianxun

    2014-03-01

    In order to prevent possible damages to soft tissues, reliable monitoring methods are required to provide valuable information on the condition of the bone being cut. This paper describes the design of an electrical impedance sensing drill developed to estimate the relative position between the drill and the bone being drilled. The two-electrode method is applied to continuously measure the electrical impedance during a drill feeding movement: two copper wire brushes are used to conduct electricity in the rotating drill and then the drill is one electrode; a needle is inserted into the soft tissues adjacent to the bone being drilled and acts as another electrode. Considering that the recorded electrical impedance is correlated with the insertion depth of the drill, we theoretically calculate the electrode-tissue contact impedance and prove that the rate of impedance change varies considerably when the drill bit crosses the boundary between two different bone tissues. Therefore, the rate of impedance change is used to determine whether the tip of the drill is located in one of cortical bone, cancellous bone, and cortical bone near a boundary with soft tissue. In vitro experiments in porcine thoracic spines were performed to demonstrate the feasibility of the impedance sensing drill. The experimental results indicate that the drill, used with the proposed data-processing method, can provide accurate and reliable breakthrough detection in the bone-drilling process. PMID:24254254

  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. New Method for Separation of Electrode Polarization Impedance from Measured Tissue Impedance

    PubMed Central

    Kalvøy, Håvard; Johnsen, Gorm K; Martinsen, Ørjan G; Grimnes, Sverre

    2011-01-01

    In this paper we have shown that electrode polarization impedance (EPI) can be separated from measured tissue impedance as long as the characteristic frequencies of EPI and tissue are not too close, so that the EPI is largely displayed as a separate dispersion. In 2-electrode measurements the EPI and sample are physically connected in series, and commonly modelled by equivalent components in series. We have calculated the parallel equivalent elements and converted the series connected EPI and sample to a parallel admittance model. By curve fitting on the converted model we have shown that this provides a new method for estimating the EPI with enhanced accuracy compared to similar techniques used on the impedance model. PMID:21625369

  5. Measurement of the harmonic distortion of the insulation loss current as a diagnostic tool for high voltage cable insulation

    Microsoft Academic Search

    A. T. Bulinski; E. So; S. S. Bamji

    2000-01-01

    The 60 Hz insulation loss current measurements in high voltage cable insulation containing water trees are described. To isolate the small insulation loss current from the significantly larger, quadrature (capacitive) current, a current-comparator-based high voltage capacitance bridge was used. It is shown that water trees introduce higher harmonics into the insulation loss current waveform and that the harmonic distortion of

  6. Measuring Ca(2+) binding to short chain fatty acids and gluconate with a Ca(2+) electrode: role of the reference electrode.

    PubMed

    Stumpff, Friederike; McGuigan, John A S

    2014-08-15

    Many organic anions bind free Ca(2+), the total concentration of which must be adjusted in experimental solutions. Because published values for the apparent dissociation constant (Kapp) describing the Ca(2+) affinity of short chain fatty acids (SCFAs) and gluconate are highly variable, Ca(2+) electrodes coupled to either a 3M KCl or a Na(+) selective electrode were used to redetermine Kapp. All solutions contained 130mM Na(+), whereas the concentration of the studied anion was varied from 15 to 120mM, replacing Cl(-) that was decreased concomitantly to maintain osmolarity. This induces changes in the liquid junction potential (LJP) at the 3M KCl reference electrode, leading to a systematic underestimation of Kapp if left uncorrected. Because the Na(+) concentration in all solutions was constant, a Na(+) electrode was used to directly measure the changes in the LJP at the 3 M KCl reference, which were under 5mV but twice those predicted by the Henderson equation. Determination of Kapp either after correction for these LJP changes or via direct reference to a Na(+) electrode showed that SCFAs do not bind Ca(2+) and that the Kapp for the binding of Ca(2+) to gluconate at pH 7.4, ionic strength 0.15M, and 23°C was 52.7mM. PMID:24835426

  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. Effect of atmospheric pressure dielectric barrier discharge air plasma on electrode surface

    NASA Astrophysics Data System (ADS)

    Wang, Changquan; He, Xiangning

    2006-11-01

    In order to study the influence of plasma on electrode, atmospheric pressure dielectric barrier discharge (DBD) air plasma is employed here to treat copper electrode surface. Plasma is generated between the parallel plate electrodes by means of high voltage produced by a high-frequency power supply with transformer. Electrode surface alterations induced by air plasma are investigated by using field emission scanning electron microscope (FE-SEM), X-ray energy dispersion spectroscopy (EDS) and contact angle measurement. The results show that DBD air plasma removes the organic contaminant on surface and causes electrode surface roughness, oxidization and nitridation. In addition, surface wettability is also improved, as concluded from contact angle measurements.

  9. 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.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    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/m3 × 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/m3 of thoron decay products were measured.

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

    PubMed

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

    2014-02-01

    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(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(3) of thoron decay products were measured. PMID:24593339

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

    SciTech Connect

    Gierl, Stefanie; Meisenberg, Oliver, E-mail: oliver.meisenberg@helmholtz-muenchen.de; Wielunski, Marek; Tschiersch, Jochen [Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg (Germany)] [Helmholtz Zentrum München, German Research Center for Environmental Health, Institute of Radiation Protection, Ingolstädter Landstr. 1, 85764 Neuherberg (Germany); Haninger, Thomas [Helmholtz Zentrum München, German Research Center for Environmental Health, Auswertungsstelle für Strahlendosimeter, Otto-Hahn-Ring 6, 81739 München (Germany)] [Helmholtz Zentrum München, German Research Center for Environmental Health, Auswertungsstelle für Strahlendosimeter, Otto-Hahn-Ring 6, 81739 München (Germany)

    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.

  14. 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.

  15. RF Currents Produced from AC Arcs with Asymmetrical Electrodes

    Microsoft Academic Search

    John J. Shea; Xin Zhou

    2010-01-01

    The RF current (0-20MHz) produced by an air arc with asymmetrical (graphite-copper) electrodes was investigated for 120Vac 60Hz over a current range of 1.2Arms to 45Arms. Time resolved spectral signatures of measured RF currents showed amplitude dependence on 60 Hz arc current level, voltage polarity, electrode material, and circuit impedance. For most conditions, RF currents were measured only when the

  16. Dark current-voltage measurements on photovoltaic modules as a diagnostic or manufacturing tool

    SciTech Connect

    King, D.L.; Hansen, B.R.; Quintana, M.A.; Kratochvil, J.A.

    1997-10-01

    Dark current-voltage (dark I-V) measurements are commonly used to analyze the electrical characteristics of solar cells, providing an effective way to determine fundamental performance parameters without the need for a solar simulator. The dark I-V measurement procedure does not provide information regarding short-circuit current, but is more sensitive than light I-V measurements in determining the other parameters (series resistance, shunt resistance, diode factor, and diode saturation currents) that dictate the electrical performance of a photovoltaic device. The work documented here extends the use of dark I-V measurements to photovoltaic modules, illustrates their use in diagnosing module performance losses, and proposes their use for process monitoring during manufacturing.

  17. Rapid pH change due to bacteriorhodopsin measured with a tin-oxide electrode.

    PubMed Central

    Robertson, B; Lukashev, E P

    1995-01-01

    The photocurrent transient generated by bacteriorhodopsin (bR) on a tin-oxide electrode is due to pH change and not to charge displacement as previously assumed. Films of either randomly oriented or highly oriented purple membranes were deposited on transparent electrodes made of tin-oxide-coated glass. The membranes contained either wild-type or D96N-mutant bR. When excited with yellow light through the glass, the bR pumps protons across the membrane. The result is a rapid local pH change as well as a charge displacement. Experiments with these films show that it is the pH change rather than the displacement that produces the current transient. The calibration for the transient pH measurement is given. The sensitivity of a tin-oxide electrode to a transient pH change is very much larger than its sensitivity to a steady-state pH change. PMID:7787036

  18. Optimizing of electrode system with central object in electrical impedance tomography

    Microsoft Academic Search

    Yan Wang; Hong Sha; Shu Zhao; Chaoshi Ren

    2009-01-01

    Electrical impedance tomography (EIT) is one of the important research topics in today's biomedical engineering. EIT system applies currents through electrodes attached to the surface of the human body and measures the resulting voltages to reconstruct and display approximate pictures of the electric conductivity and permittivity inside the body. Electrode lies in the front of the whole EIT system and

  19. A novel, remote-controlled suspension device for brain tissue PO2 measurements with multiwire surface electrodes.

    PubMed

    Murr, R; Berger, S; Schürer, L; Peter, K; Baethmann, A

    1994-02-01

    A new device was developed for rapid assessment of PO2 values in viable tissue, such as the brain, using a multiwire surface electrode. The instrument utilizes a phonograph-like construction with weightless suspension of the electrode which thus minimizes surface pressure and allows for compensation of brain movements. The new and original component of the present device is the motor-driven, servo-controlled rotation of the PO2 electrode around its vertical axis. This enables PO2 measurements from precisely defined locations. From values measured on rabbit brain surface a PO2 histogram was constructed. The mean PO2 and distribution histogram were similar to those obtained with a needle electrode. The novel device, therefore, enables accurate and fast tissue PO2 measurements with minimal risk of brain damage. PMID:8183646

  20. Investigation of the effect of blocking potential on the static breakdown voltage and discharge initiation in pseudospark switches

    SciTech Connect

    Bochkov, V.D.; Kolesnikov, A.V.; Korolev, Y.D.; Rabotkin, V.G.; Frantz, O.B.; Shemyakin, I.A. [Russian Academy of Sciences, Tomsk (Russian Federation). High current Electronics Institute] [Russian Academy of Sciences, Tomsk (Russian Federation). High current Electronics Institute

    1995-06-01

    The measurement data on the currents in the pre breakdown phase and the static breakdown voltage for the pseudospark switch with a blocking electrode and a trigger unit based on an auxiliary glow discharge are presented the use of the blocking electrode offers the possibility to extend the range of operation pressures for the switch with conservation of a high level of static breakdown voltage and low level of delay time. It is shown that the effect of the blocking electrode on the static breakdown voltage is due to suppression of the hollow cathode effect in the main gap of the switch.

  1. Electronic measurement of the Boltzmann constant with a quantum-voltage-calibrated Johnson noise thermometer

    NASA Astrophysics Data System (ADS)

    Benz, Samuel; White, D. Rod; Qu, JiFeng; Rogalla, Horst; Tew, Weston

    2009-11-01

    Currently, the CODATA value of the Boltzmann constant is dominated by a single gas-based thermometry measurement with a relative standard uncertainty of 1.8×10 [P.J. Mohr, B.N. Taylor, D.B. Newell, CODATA recommended values of the fundamental physical constants: 2006, Rev. Mod. Phys. 80 (2008) 633-730]. This article describes an electronic approach to measuring the Boltzmann constant that compares Johnson noise from a resistor at the water triple point with a pseudo-random noise generated using quantized ac-voltage synthesis. Measurement of the ratio of the two power spectral densities links Boltzmann's constant to Planck's constant. Recent experiments and detailed uncertainty analysis indicate that Boltzmann's constant can presently be determined using Johnson noise with a relative standard uncertainty below 10×10, which would support both historic and new determinations. To cite this article: S. Benz et al., C. R. Physique 10 (2009).

  2. Numerical Electric Field Analysis of Power Status Sensor Observing Power Distribution System Taking into Account Voltage Divider Measurement Circuit

    NASA Astrophysics Data System (ADS)

    Kubo, Takuro; Furukawa, Tatsuya; Itoh, Hideaki; Fukumoto, Hisao; Wakuya, Hiroshi; Ohchi, Masashi

    We have proposed and preproducted the voltage-current waveform sensor of resin molded type for measuring the power factor and harmonics in power distribution systems. We have executed numerical electromagnetic analyses using the finite element method to estimate the characteristics and behaviours of the sensor. Although the magnetic field analyses for the current sensor have involved the measurement circuit, the electric field analyses have not included the measurement circuit for measuring voltage waveforms of power lines. In this paper, we describe the electric field analyses with the measurement circuit and prove the insulating strength of the proposed sensor permissible to the use in 22kV power distribution systems.

  3. Destruction of living cells by pulsed high-voltage application

    Microsoft Academic Search

    A. Mizuno; Y. Hori

    1988-01-01

    Destruction of living cells in liquid has been formed by pulsed high-voltage application to the liquid. S. cerevsaie (yeast cell) or Bacillus natto, dispersed in deionized water and one- and three-percent NaCl solution, were used in this experiment. Four different electrodes (plate-plate, needle-plate wire-cylinder, and rod-rod electrode) were tested. The survival rate of cells was measured against peak electric field

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

    E-print Network

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

    2015-01-28

    were carried out from 100 Hz to 10 MHz. 2.3 Preparation of DNA samples with different concentrations Herring sperm DNA was ordered from SIGMA-ALDRICH (D7290). The single-stranded DNA fragments ranged in size from 587 to 831 base pairs. This DNA... concentration test The DNA sample concentration tests were performed with the CMOS chip and external thin-film electrodes, as described in Section 2. Five groups of herring sperm DNA samples with different concentrations were characterized. The measurements...

  5. Langmuir probe measurements of low pressure, low voltage DC plasma system

    NASA Astrophysics Data System (ADS)

    Hagedorn, Michael Stanley

    1999-11-01

    A Langmuir probe was built and software was developed to control the probe via a lock-in amplifier and to aid in automated data gathering and analysis. The probe was installed in a low pressure, low voltage DC plasma system that is currently being used to grow polymerized organo-silicon films. The hypothesis is that in a low pressure, low voltage DC plasma system, the electron mean free path is long enough that collisions are rare and that the electron energies are low enough that upon collision, an electron can only cause single ionization to occur. This should result in an electron population with a well defined, narrow distribution in energy. If the electron energy distribution is narrow enough, it should be possible to measure the energy distributions of the electrons that were involved in collisions and thereby determine which ionizations (and hence what chemistries) are occurring in the plasma. The purpose of this research is to characterize the performance of the Langmuir probe and examine the probe's interaction with the plasma system. The probe will then be used to make measurements of a process plasma and test the hypothesis.

  6. Membrane Potential Measurements of Isolated Neurons Using a Voltage-Sensitive Dye

    PubMed Central

    Fairless, Richard; Beck, Andreas; Kravchenko, Mykola; Williams, Sarah K.; Wissenbach, Ulrich; Diem, Ricarda; Cavalié, Adolfo

    2013-01-01

    The ability to monitor changes in membrane potential is a useful tool for studying neuronal function, but there are only limited options available at present. Here, we have investigated the potential of a commercially available FLIPR membrane potential (FMP) dye, developed originally for high throughput screening using a plate reader, for imaging the membrane potential of cultured cells using an epifluorescence-based single cell imaging system. We found that the properties of the FMP dye make it highly suitable for such imaging since 1) its fluorescence displayed a high signal-to-noise ratio, 2) robust signals meant only minimal exposure times of around 5 ms were necessary, and 3) bidirectional changes in fluorescence were detectable resulting from hyper- or depolarising conditions, reaching equilibrium with a time constant of 4–8 s. Measurements were possible independently of whether membrane potential changes were induced by voltage clamping, or manipulating the ionic distribution of either Na+ or K+. Since FMP behaves as a charged molecule which accumulates in the cytosol, equations based on the Boltzmann distribution were developed determining that the apparent charge of FMP which represents a measure of the voltage sensitivity of the dye, is between ?0.62 and ?0.72. Finally, we demonstrated that FMP is suitable for use in a variety of neuronal cell types and detects membrane potential changes arising from spontaneous firing of action potentials and through stimulation with a variety of excitatory and inhibitory neurotransmitters. PMID:23516458

  7. 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.

  8. Evaluation of Electrophoretic Migration by Optical and Current Responses to Cyclic-Polarity-Reversed Triangular Voltage

    NASA Astrophysics Data System (ADS)

    Sugita, Tatsuya; Ohshima, Tetsuya

    2011-12-01

    We studied the electrophoretic migration of electrophoretic inks by measuring the total reflection at the interface between the electrode and the ink solvent simultaneous with the current response to a cyclic-polarity-reversed triangular voltage. We demonstrated that the current peaks and optical responses to the cyclic-polarity-reversed triangular voltage are effective for the easy evaluation of mobility, the charge amount of ions and ink particles, and the interactions of particles with the electrode and inter-particles. The mobility of the ink particles was measured from the slopes of these peak voltages as functions of the square root of the time rate of the scanning voltage. The offset of line extrapolation indicated the interaction of the particles with the electrode. The optical response was effective for measuring the mobility even when the conductivity of the cell was too large to detect the drift current peaks.

  9. Surface Plasmon Resonance in Organic Photovoltaic Cells with Silver or Gold Electrodes

    Microsoft Academic Search

    Kumiko Yamagishi; Junichi Inoue; Masafumi Yamashita

    2006-01-01

    The enhancement of photocurrent in organic photovoltaic cells by excitation of surface plasmon resonance (SPR) is shown to be greater for Ag electrodes than for Au electrodes. Three-layer Al\\/tin-phthalocyanine\\/(Ag,Au) photovoltaic cells are fabricated by vacuum evaporation, and the current–voltage characteristics measured with and without excitation of SPR at the metal–dielectric interface. Excitation of SPR increased photocurrent in the Ag-electrode cell

  10. Cable properties of cat spinal motoneurones measured by combining voltage clamp, current clamp and intracellular staining.

    PubMed Central

    Clements, J D; Redman, S J

    1989-01-01

    1. Spinal alpha-motoneurones were injected with horseradish peroxidase after measuring their voltage response to a brief current pulse and their current response to a small voltage step. 2. The morphology of each motoneurone was reconstructed from serial sections. The diameters and lengths of dendritic segments were used to build a compartmental model of each neurone's electrotonic structure. The specific resistivity of the membrane (Rm) was assumed to be constant throughout the dendrites, but it was lowered for the somatic membrane by the introduction of a somatic shunt resistance. 3. The specific resistances of the somatic and dendritic membrane were adjusted in the compartmental model until the responses of the model to the same current and voltage steps as those used in the experiment gave the best fits to the recorded transients. Satisfactory fits were obtained for six out of seven motoneurones. Dendritic Rm varied from 7 to 35 k omega cm2 and somatic Rm varied from 100 to 420 omega cm2. The dendritic Rm was 100-300 times the somatic Rm for different neurones. 4. The calculated dendritic Rm was used to determine the geometric profile of the equivalent dendritic cable. This was found to be an approximately uniform cylinder for about 0.5 lambda and thereafter to taper rapidly to a final termination at 2-3 lambda from the soma. 5. The results indicate that motoneurone dendrites are more electrically compact than was hitherto believed. The different Rm values for somatic and dendritic membrane, and the tapering of the dendritic cable, means that the cable model developed by Rall (1959, 1964) must be revised to take account of these spatial and electrical non-uniformities. PMID:2585300

  11. Emulsion stability measurements by single electrode capacitance probe (SeCaP) technology

    NASA Astrophysics Data System (ADS)

    Schüller, R. B.; Løkra, S.; Salas-Bringas, C.; Egelandsdal, B.; Engebretsen, B.

    2008-08-01

    This paper describes a new and novel method for the determination of the stability of emulsions. The method is based on the single electrode capacitance technology (SeCaP). A measuring system consisting of eight individual measuring cells, each with a volume of approximately 10 ml, is described in detail. The system has been tested on an emulsion system based on whey proteins (WPC80), oil and water. Xanthan was added to modify the emulsion stability. The results show that the new measuring system is able to quantify the stability of the emulsion in terms of a differential variable. The whole separation process is observed much faster in the SeCaP system than in a conventional separation column. The complete separation process observed visually over 30 h is seen in less than 1.4 h in the SeCaP system.

  12. Electrode displacement measurement dynamics in monitoring of small scale resistance spot welding

    NASA Astrophysics Data System (ADS)

    Chen, J. Z.; Farson, D. F.

    2004-12-01

    Small-scale resistance spot welding (SSRSW) process is widely used in medical and electronic devices manufacturing, where it is used to join thin foils and fine wires. Although tremendous work has been focused on traditional RSW process monitoring and control, SSRSW has received less attention, one reason being the process variables that are used in monitoring and control are very small in magnitude. A good example of a process variable that presents this difficulty is electrode displacement, which is generally regarded as one of the variables that can provide real-time information useful for monitoring and controlling RSW process quality. However, in SSRSW production, it is difficult to measure the displacement because its magnitude is very small. In this work, a fibre optic sensor was used for displacement monitoring. It was discovered that the implementation of the sensor introduced extraneous transient fluctuations into the measured signature. To develop techniques to improve the accuracy of the fibre optic sensor displacement measurements, more reliable electrode movement data were obtained using a high-speed video set-up. It was found that the displacement obtained by the fibre optic sensor had a delay and oscillatory feature compared to true displacement. Although it is a valuable research tool, the high-speed video system is not practical for online monitoring and control, while the fibre optic sensor has more potential for real-time monitoring and control implementation. Therefore, attempts were made to recover true displacement from the contaminated fibre optic displacement. A number of dynamic models in state-space form were identified to decode and predict the true displacement from fibre optic sensor measurement. Model parameters were estimated from two sets of known displacement data with fibre optic sensor displacement as input and high-speed video displacement as output. A fifth order innovations form model optimized by the subspace method was found to have the best accuracy compared to high-speed video measurement. Compared to uncorrected fibre optic and high-speed video displacement, fibre optic measurements corrected by this model are promising for real-time monitoring and control algorithms that use electrode displacement measurements.

  13. Schottky Barrier Height Determination by Capacitance-Voltage Measurement on n-GaN with Exponential Doping Profile

    Microsoft Academic Search

    Naotaka Kubota; Jin-Ping Ao; Daigo Kikuta; Yasuo Ohno

    2004-01-01

    A capacitance-voltage (C-V) method was developed to extrapolate the Schottky barrier height on n-GaN with exponential carrier concentration profile. The carrier concentration profile of the unintentionally doped GaN was determined by C-V measurement to be exponential. On the basis of this profile, one-dimensional Poisson's equation was calculated to obtain the relation between bias voltage and depletion width. Schottky barrier height

  14. Fluid flow rate measurement using the change in laser junction voltage due to the self-mixing effect

    Microsoft Academic Search

    J. R. Tucker; Yah Leng Lim; K. Bertling; A. V. Zvyagin; A. D. Rakic

    2006-01-01

    We report on the first measurement of the liquid flow rate utilizing the variation in junction voltage across a laser due to the self-mixing effect. A packaged single-mode VCSEL with integrated photodiode is used as the self-mixing sensor. Signal was acquired from both the photodiode and the laser junction voltage. With appropriate signal processing, both detection methods produced comparable results

  15. Characterization of an ion sensitive field effect transistor and chloride ion selective electrodes for pH measurements in seawater.

    PubMed

    Takeshita, Yuichiro; Martz, Todd R; Johnson, Kenneth S; Dickson, Andrew G

    2014-11-18

    Characterization of several potentiometric cells without a liquid junction has been carried out in universal buffer, aqueous HCl, and artificial seawater media. The electrodes studied include Ion Sensitive Field Effect Transistor (ISFET) pH electrodes, and Chloride-Ion Selective Electrodes (Cl-ISE) directly exposed to the solution. These electrodes were compared directly to the conventional hydrogen electrode and silver-silver chloride electrode in order to report the degree to which they obey ideal Nernstian laws. These data provide a foundation for operating the ISFET|Cl-ISE pair in seawater as a pH sensor. In order to obtain the highest quality pH measurements from this sensor, its response to changes in pH and salinity must be properly characterized. Our results indicate near-ideal Nernstian response for both electrodes over a wide range of pH (2-12) and Cl(-) molality (0.01-1). We conclude that the error due to sub-Nernstian response of the cell ISFET|seawater|Cl-ISE over the range of seawater pH and salinity is negligible (<0.0001 pH). The cross sensitivity of the Cl-ISE to Br(-) does not seem to be a significant source of error (<0.003 pH) in seawater media in the salinity range 20-35. PMID:25325617

  16. 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.

  17. Modified design of radioisotope thermophotovoltaic generator to mitigate adverse effect of measured cell voltage

    SciTech Connect

    Schock, A.; Or, C.T.; Kumar, V. [Orbital Sciences Corp., Germantown, MD (United States)

    1996-12-31

    A preceding OSC paper described a number of changes in the data base and in the methods--considerably more rigorous than those employed in the past--for analyzing the performance of Radioisotope Thermophotovoltaic (RTPV) converters. As shown, some of those changes were beneficial, but others--particularly the use of EDTEK`s experimentally measured open-circuit voltages and fill factors instead of previously used theoretical equations--had a substantial adverse effect on the predicted converter performance. EDTEK is continuing work on improved PV cells to more closely approach theoretical voltage predictions. In parallel with that effort, OSC has been investigating a number of generator design modifications to achieve additional improvements in system performance. Specifically, OSC found that the converter`s performance could be significantly improved by increasing the heat flux incident on the PV cells. As will be explained, OSC`s preferred design, which entails placing the TPV converters on the housing`s end covers instead of its side walls, not only improves the generator`s performance but also offers important programmatic, fabrication, and processing advantages.

  18. 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

  19. 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.

  20. Voltage sag detection based on rectified voltage processing

    Microsoft Academic Search

    Andrea Florio; Andrea Mariscotti; Maurizio Mazzucchelli

    2004-01-01

    An algorithm for voltage sag detection based on rectified voltage processing is presented and its performances are evaluated by means of simulated and real voltage waveforms (recorded at some low-voltage busbars and measured on a scaled prototype of a voltage support system). The algorithm is intended to detect voltage sag occurrence and to trigger the disconnection of the faulty supply

  1. The five percent electrode system for high-resolution EEG and ERP measurements

    Microsoft Academic Search

    Robert Oostenveld; Peter Praamstra

    2001-01-01

    Objective: A system for electrode placement is described. It is designed for studies on topography and source analysis of spontaneous and evoked EEG activity.Method: The proposed system is based on the extended International 10–20 system which contains 74 electrodes, and extends this system up to 345 electrode locations.Results: The positioning and nomenclature of the electrode system is described, and a

  2. Analysis of impedance measurements at lithium electrodes allowing for semiconductor aspects of passivating film. Lithium perchlorate solution in propylene carbonate

    SciTech Connect

    Shembel', E.M.; Ksenzhek, O.S.; Maksyuta, I.M.

    1986-04-01

    This paper analyzes impedance measurements at lithium electrodes in nonaqueous electrolytes in order to determine the electrochemical parameters of the film which is formed on the lithium surface and influences the characteristics of high-energy-density lithium batteries. The passivating film is discussed in terms of its semiconductor aspects. This study has enabled the authors to determine the characteristics of space charge and surface states, and to compare the parameters of the primary and secondary film. At an anodically pretreated electrode, the capcitance is higher while the resistance determined from the impedance plot changes much more slowly during ''aging'' of the electrode than it does at a lithium electrode where the surface had been cut.

  3. Localized, low-voltage electro-osmotic pumping across nanoporous membranes

    NASA Astrophysics Data System (ADS)

    Gupta, A.; Denver, H.; Hirsa, A. H.; Stenken, J. A.; Borca-Tasciuc, D.-A.

    2007-08-01

    This work demonstrates the principle of localized, low-voltage, continuous current electro-osmotic pumping across thin membranes. Localization of the pumping effect is obtained by employing ring electrodes, microfabricated on each side of nanoporous alumina membranes. Low voltage actuation is achieved by having the separation of the two electrodes in the microscale range—the thickness of the membrane. The measured electro-osmotic velocity increases linearly from 40?m/s at 5V to 200?m/s at 20V. Experimental results compare well with predictions of an electro-osmotic flow model considering the nonuniform distribution of the electric field between the electrodes.

  4. A generic automated\\/semiautomated digital multi-electrode instrument for field resistivity measurements

    Microsoft Academic Search

    Douglas D. Werkema; Estella Atekwana; William Sauck; Johnson A. Asumadu

    2000-01-01

    The objective of this work is to design and test a digital multi-electrode acquisition system for use in geophysical investigations utilizing direct current electrical (geoelectric) methods. The system is a 64-electrode modular system, which utilizes field electrodes with individual wires that lead back to a digital switch box and then to a data acquisition instrument (Iris Syscal R2). The electronic

  5. 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.

  6. 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.

  7. Accurate fault location of two-terminal transmission line based on one end voltage measurement and Smooth Support Vector Machines

    Microsoft Academic Search

    Eyada A J Alanzi; Mahmoud A A Younis

    2011-01-01

    This paper presents a new technique for accurate fault location based on voltage measurement from one end of the two-terminal transmission line and Smooth Support Vector Machine (SSVM). Due to common problems of current transformer during fault location and as a result increasing the cost and reduction of the accuracy, proposed technique is independent of current measurement and based on

  8. 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.

  9. Monitoring of magnetron target poisoning by measurement of higher harmonics of discharge voltages

    NASA Astrophysics Data System (ADS)

    Dvo?ák, P.; Vašina, P.

    2010-10-01

    Reactive magnetron sputtering suffers from processing stability problems and the optimal experimental conditions for thin film deposition usually lie very close to an abrupt transition from the metallic to the compound mode. Therefore, a fast feedback method is needed to automatically control either the flow of the reactive gas, or the discharge power to keep the process at the desired operating point. A promising method for this process of monitoring, based on the measurement of amplitudes of higher harmonic frequencies of discharge voltages, is proposed. The measurement of the amplitudes can be performed either by an uncompensated probe in the plasma or on the cable between the RF generator and the sputtered target. The sensitivity of the proposed method is significantly better than measurement of other electrical quantities conventionally used for process control. Physical reasons for the change in amplitudes of higher harmonic frequencies during the mode transition are found. The paper shows that the observed changes in amplitudes of higher harmonics by the transition are not caused either by the pressure change, or by the changes in the composition of the gas in the reactor volume. It is found that the amplitudes of higher harmonics reflect primarily the state of the magnetron target poisoning. The amplitudes thus belong to a group of process parameters representing the target state, which are considered to be the best for reliable process control.

  10. Breakdown measurements of ultra-thin SiO2 at low voltage

    Microsoft Academic Search

    J. H. Stathis; A. Vayshenker; P. R. Varekamp; E. Y. Wu; C. Montrose; J. McKenna; D. J. DiMaria; L.-K. Han; E. Cartier; R. A. Wachnik; B. P. Linder

    2000-01-01

    MOSFETs with oxide thickness from tox=1.4 to 2.2nm have been stressed for times exceeding one year, at voltages in the range V g=1.9-4V. The data are compared with previous model calculations. The voltage acceleration of the charge-to-breakdown (QBD) is explained in terms of a weak yet statistically significant voltage dependence of the critical defect density at breakdown (NBD), and a

  11. High-speed, random-access fluorescence microscopy: II. Fast quantitative measurements with voltage-sensitive dyes.

    PubMed

    Bullen, A; Saggau, P

    1999-04-01

    An improved method for making fast quantitative determinations of membrane potential with voltage-sensitive dyes is presented. This method incorporates a high-speed, random-access, laser-scanning scheme (Bullen et al., 1997. Biophys. J. 73:477-491) with simultaneous detection at two emission wavelengths. The basis of this ratiometric approach is the voltage-dependent shift in the emission spectrum of the voltage-sensitive dye di-8-butyl-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (di-8-ANEPPS). Optical measurements are made at two emission wavelengths, using secondary dichroic beamsplitting and dual photodetectors (<570 nm and >570 nm). Calibration of the ratiometric measurements between signals at these wavelengths was achieved using simultaneous optical and patch-clamp measurements from adjacent points. Data demonstrating the linearity, precision, and accuracy of this technique are presented. Records obtained with this method exhibited a voltage resolution of approximately 5 mV, without any need for temporal or spatial averaging. Ratiometric recordings of action potentials from isolated hippocampal neurons are used to illustrate the usefulness of this approach. This method is unique in that it is the first to allow quantitative determination of dynamic membrane potential changes in a manner optimized for both high spatiotemporal resolution (2 micrometers and <0.5 ms) and voltage discrimination. PMID:10096922

  12. Metal Electrode Formation on Organic Film Using Xe-Buffer-Layer-Assisted Deposition for Efficient Measurement of Inelastic Tunneling Spectroscopy

    NASA Astrophysics Data System (ADS)

    Rahim, Abdur; Liu, Jie; Fakruddin Shahed, Syed Mohammad; Komeda, Tadahiro

    2013-10-01

    We demonstrate that, by using a Xe-buffer-layer-assisted deposition, a metal electrode can be formed on an organic film without altering the chemical properties of the molecules. A new efficient measurement of inelastic tunneling spectroscopy (IETS) was demonstrated by attaching the scanning tunneling microscopy (STM) tip to the Au cluster. Au electrode was formed on a Xe buffer layer condensed on an alkanethiol self-assembled monolayer (SAM), in which the Xe layer prevents direct interaction between hot metal atoms and molecules in the film. An IETS measurement executed with the new method revealed the robustness of the molecules at the metal-film interface.

  13. 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.

  14. Electrochemically self-assembled ZnO/dye electrodes: preparation and time-resolved photoelectrochemical measurements

    NASA Astrophysics Data System (ADS)

    Schlettwein, Derck; Oekermann, Torsten; Yoshida, Tsukasa; Sugiura, Takashi; Minoura, Hideki; Wohrle, Dieter

    2002-11-01

    Dye-modified ZnO thin films were prepared by electrochemically induced crystallization from aqueous mixtures of zinc nitrate and water-soluble dyes. A direct crystallization of semiconductor/ dye composites without heat treatment is seen as a significant advantage of this method. Moreover, characterization of these materials has revealed ordered growth of ZnO crystallites as well as formation of ordered dye assemblies, thus characterizing this method as electrochemical self-assembly. The photoelectrochemical properties of these unique ZnO-dye thin film electrodes were investigated in photocurrent transient measurements in the ms-regime and by steady- state voltammetric measurements. Two sets of electrodes are discussed, employing either metal complexes of tetrasulfophthalocyanines (TSPcMt; Mt = Zn, Al, Si) or the xanthene dye Eosin Y. For aggregates of TSPcMt on ZnO, efficient charge-transfer to the electrolyte is found, leading to low surface charging and low surface recombination of photogenerated holes with electrons from the ZnO, at however, rather low injection efficiencies of electrons into the conduction band of ZnO. This efficiency was higher for adsorbed monomers of TSPcMt leading to a considerably higher quantum efficiency of the photocurrent in spite of increased surface charging and recombination of holes. Higher photocurrents were observed for ZnO sensitized with monomers of Eosin Y caused by both, efficient electron transfer from the dye to ZnO as well as hole transfer from the dye to the electrolyte. Not only dye molecules which were directly accessible from the electrolyte, but also those which were enclosed within matrix cavities proved to be photoelectrochemically active.

  15. Development of New Electrode System for High Field Dielectric Properties Measurement Using Evaporated Polypropylene Thin Guard Film

    NASA Astrophysics Data System (ADS)

    Fujii, Masayuki; Tohyama, Kazuyuki; Tokoro, Tetsuro; Mizuno, Yukio; Nagao, Masayuki; Kosaki, Masamitsu

    Non-polar polymers such as polyethylene (PE) and polypropylene (PP) are widely used as very important electrical insulating and dielectric materials. They are used in the increasingly high AC electric field strength region approaching to the limit of electrical breakdown strength of the materials. Therefore the study of high-field dielectric property is very important in terms of understanding the AC breakdown mechanism of materials. A three-terminals electrode system with a guard film (new type electrode system) was developed in our laboratory for the precise measurement of high-field tan?, where the guard film was used to reduce the disturbance of electric field around the edge of a main electrode. However, minute air sometimes steals between a sample film and the guard film. The air sometimes generates partial discharge in the high electric field region. Therefore, when the sample had minute air, the new type electrode system was limited under 100kVrms/mm application that didn't reach to an intrinsic breakdown strength of the 30?m-thick sample. We tried to improve the new electrode system without minute air between a sample film and the guard film. We also tried to make very thin guard film to reduce the field disturbance at the edge of main electrode. In this paper a PP-guard film on a biaxially oriented polypropylene (BOPP) film was made by evaporation. This improvement of the electrode system using the evaporated PP-guard film was in success so that high-field dielectric properties of BOPP film could be measured up to near the intrinsic breakdown field of the sample.

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

    PubMed

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

    2013-02-01

    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(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. PMID:23464200

  17. Estimation of Backward Impedance on Low-Voltage Distribution System using Measured Resonant Current

    NASA Astrophysics Data System (ADS)

    Miki, Toru; Konishi, Kazuki; Morimoto, Koji; Nagaoka, Naoto; Ametani, Akihiro

    Two estimation methods for a backward impedance of a power distribution system are proposed in this paper. A frequency response of a transient current flowing into a capacitor, which connected to a distribution line, has information of the backward impedance. The impedance is obtained from an attenuation constant and a resonance frequency determined by the capacitance and the impedance of power distribution system. These parameters are stably obtained from a frequency response of the transient current using a least square method. The accuracy of the method heavily depends on the origin on the time-axis for Fourier transform. Additional time-origin estimation is required for an accurate estimation of the backward impedance. The second method estimates the backward impedance using two transient current waveforms obtained by connecting alternately different capacitors to a distribution line. The backward impedance can be represented as a function of the frequency responses of these current. This method is suitable for an automatic measurement of the backward impedance because the method is independent from the time-origin. The proposed methods are applicable to an estimation of a harmonic current of the distribution system. In this paper, a harmonic current flowing through a distribution wire is estimated from the estimated backward impedance and the measured results of harmonic voltages obtained by an instrument developed by the authors.

  18. A novel measurement technique for extra high voltage bus bar fault detection

    Microsoft Academic Search

    S. H. Haggag; Ali M. El-Rifaie; R. M. Sharkawy

    2012-01-01

    This paper introduces a new fault detection tool for Extra High Voltage (EHV) busbars. The new tool is to be used by extra high speed digital relays to detect busbar faults besides differentiating between close up line faults and busbar ones. The suggested tool uses a new technique that squares both of the instantaneous voltage signal and its complement to

  19. Three-dimensional electric field calculation and measurements inside high voltage substations

    Microsoft Academic Search

    Sayed A. Word; Samy M. Ghania; Essam M. Shaalan

    2011-01-01

    The exposure to electric field now-a-days is an integral part in the design area of electrical power apparatus and systems. Moreover the electric field produced by power lines, busbars and all high voltage equipments inside high voltage (HV) substations is receiving more and more concerns to guarantee the safety of workers inside these substations. Therefore monitoring the electric field inside

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

    E-print Network

    factors for the voltage stability problem, etc. II. FUNDAMENTALS: SIGLE GENERATOR AND LOAD SYSTEM #12;A to find the most vulnerable area in a system, to find the impacts of other loads, areas and power, Transient Analysis I. INTRODUCTION Voltage stability is a major concern in planning and operations of power

  1. Analysis of cell impedance measured on the LiMn 2O 4 film electrode by PITT and EIS with Monte Carlo simulation

    Microsoft Academic Search

    Sung-Woo Kim; Su-Il Pyun

    2002-01-01

    Cell impedance measured on a LiMn2O4 film electrode was analyzed by using the potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) with Monte Carlo simulation. The plot of the resistance of the absorption–desorption of lithium ions at the electrolyte?electrode interface vs. the electrode potential measured by EIS coincided well with the plot of the cell impedance versus the

  2. Highly efficient iodide/triiodide dye-sensitized solar cells with gel-coated reduce graphene oxide/single-walled carbon nanotube composites as the counter electrode exhibiting an open-circuit voltage of 0.90 V.

    PubMed

    Zheng, Huiqin; Neo, Chin Yong; Ouyang, Jianyong

    2013-07-24

    To increase the open-circuit voltage (Voc) of dye-sensitized solar cells (DSCs), it is crucial to enhance the photovoltaic efficiency of DSCs. Here, we report an effective method to significantly improve the Voc and photovoltaic efficiency of DSCs by using gel-coated composites of reduced graphene oxide (rGO) and single-walled carbon nanotubes (SWCNTs) as the counter electrode. Gel-coated rGO-SWCNT composites outperform Pt, rGO and SWCNTs in catalyzing the reduction of I3(-) and functioning as the counter electrode of DSCs. The Voc and power conversion efficiency (PCE) are 0.86 V and 8.37% for fresh DSCs with the composite of 80 wt % rGO and 20 wt % SWCNTs, significantly higher than those (Voc = 0.77 V, PCE = 7.79%) of control DSCs with Pt fabricated by pyrolysis as the counter electrode. The Voc value of DSCs with rGO-SWCNT composites as the counter electrode further increases to 0.90 V after one week. The high Voc and PCE are ascribed to the synergetic effects of rGO and SWCNTs in reducing the overpotential of the I3(-) reduction. RGO with high specific surface area can have high electrocatalytic activity, whereas SWCNTs give rise to high conductivity for the composites and facilitate the penetration of the redox species into rGO sheets by preventing the agglomeration of the rGO sheets. To the best of our knowledge, this is the first time to report iodide/triiodide DSCs with both high Voc and PCE. PMID:23786582

  3. Phase Current Reconstruction for AC Motor Drives using a DC-link Single Current Sensor and Measurement Voltage Vectors

    Microsoft Academic Search

    Hongrae Kim; Thomas M. Jahns

    2005-01-01

    Three-phase current measurement using only a single current sensor in the inverter dc link is appealing for ac motor drives because it minimizes the number of current sensors, thereby reducing sensor cost, weight, and volume. However, the basic dc link single current sensor technique poses special challenges because the duration of the active voltage vectors must be long enough to

  4. The correlation of capacitance-voltage hysteresis measurements with performance during accelerated lifetime testing of polycrystalline thin film solar cells

    Microsoft Academic Search

    David S. Albin

    2010-01-01

    Cell performance, or efficiency, ?% is the most used, if not most important metric for evaluating different solar cell technologies. Efficiency in turn is determined directly by the product of open-circuit voltage, Voc, short-circuit current density, Jsc, and fill-factor, FF. From numerous studies involving the measurement of ?% as a function of stress, it has been determined that ?% can

  5. Ion Beam Distributions from a Laser Ion Source with a Pair of Semicylindrical Electrodes Measured by a Multichannel Faraday Cup

    Microsoft Academic Search

    Koji Tamura

    2002-01-01

    The intensity distributions of a neodymium ion beam that was extracted from laser photoionized plasma were measured by scanning a multichannel Faraday cup. The lateral width of ions at the position of the Faraday cup, which was broad without any additional electric field, was reduced by the additional concentric potential with a pair of semicylindrical electrodes set outside of the

  6. Transparent electrode for optical switch

    DOEpatents

    Goldhar, Julius (San Ramon, CA); Henesian, Mark A. (Livermore, CA)

    1986-01-01

    A low pressure gas electrode utilizing ionized gas in a glow discharge regime forms a transparent electrode for electro-optical switches. The transparent electrode comprises 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 electrode is a transparent electrode. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. The plasma can be created either by the main high voltage pulser used to charge up the crystal or by auxiliary discharges or external sources of ionization. A typical configuration utilizes 10 torr argon in the discharge region adjacent to each crystal face.

  7. 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...

  8. 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...

  9. Development of Reliable Three-Electrode Impedance Measurements in Plastic Li-Ion Batteries

    Microsoft Academic Search

    Mickae?l Dolle?; Franc?ois Orsini; Antoni S. Gozdz; Jean-Marie Tarascona

    2001-01-01

    The electrochemical impedance spectroscopy ~EIS! is a well- developed technique used to predict the behavior of batteries, and to determine the factors limiting the performance of an electrode, in- cluding its conductivity, charge-transfer properties, properties of the passivation layer, etc. Numerous recent studies have been published on various aspects of the insertion electrodes used in lithium-ion cells as researchers attempt

  10. Measuring mercury ion concentration with a carbon nano tube paste electrode using the cyclic voltammetry method

    Microsoft Academic Search

    Suw Young LY; Sung Kuk Kim; Tae Hyun Kim; Young Sam Jung; Sang Min Lee

    2005-01-01

    A simply prepared carbon nano tube paste electrode (CNTPE) was utilized for monitoring mercury ion concentration using the cyclic voltammetry (CV) method and the square wave anodic stripping voltammetric (SWASV) method. The CNTPE was compared with various conventional electrodes. The CNTPE method was applied to determine the concentration of trace levels of Hg(II) in several water samples, which yielded a

  11. Measurement of DC and AC spectral sensitivities of retinal horizontal cells by "voltage clamp by light".

    PubMed

    Yamada, M; Yasui, S

    1988-05-01

    The method of "voltage clamp by light" was applied to measure spectral sensitivities of second-order visual neurons, namely L- and R/G-type horizontal cells in the carp retina. The present equipment employs (i) a ceramic photomodulator to facilitate a fast servomechanical control of retinal illuminance, (ii) an electronic circuit to compensate for the synaptic transmission delay, and (iii) a manual selection switch for the system to operate on negative feedback for either depolarizing or hyperpolarizing responses to light. These features allowed us to determine quickly and simultaneously both DC and AC spectral sensitivities, although the AC case was examined only at 1 Hz in this report. In L-type cells, the AC spectral sensitivity was similar in shape to the DC result. These sensitivity curves differed from microphotospectrometric absorption of red-sensitive cones: in L-type cells at both ends of the visible spectrum and in R/G units with deep-red light. PMID:3386304

  12. Open-circuit voltage improvement by using TiO2 nanotubes as a working electrode of dye-sensitized solar cell

    Microsoft Academic Search

    X. D. Li; D. W. Zhang; Z. Sun; Y. W. Chen; S. M. Huang

    2008-01-01

    The titanium dioxide nanotubes (TiNTs) were directly fabricated from commercial P25 TiO2 via alkali hydrothermal transformation. The optimized synthesis, thermal and hydrothermal stability, and consequent optical properties of the titanate nanotubes were systematically studied. The TiO2 nanotubes were characterized by transmission electron microscopy. Dye-sensitized solar cells (DSSCs) were constructed with films made of grown TiO2 nanotubes as working electrodes. The

  13. Time interval measurements using time-to-voltage conversion with built-in dual-slope A\\/D conversion

    Microsoft Academic Search

    E. Raisanen-Ruotsalainen; T. Rahkonen; J. Kostamovaara

    1991-01-01

    An integrated CMOS circuit for measuring a time interval given as the width of a pulse is presented. The circuit converts the time interval to be measured to a longer interval which can be digitized more accurately using a clock than the initial one. The circuit is a combination of a time-to-voltage converter (TVC) and a dual-slope A\\/D converter. In

  14. Design and Fabrication of a PD Measurement System for Dielectric Test of Low-voltage Electrical and Electronic Devices

    Microsoft Academic Search

    GYUNG-SUK KIL; JAE-YONG SONG; IL-KWON KIM; SEUNG-BO MOON

    2006-01-01

    Partial discharge (PD) analysis as a non-destructive dielectric test is getting spread. For the application of PD test to low-voltage electrical and electronic devices, PD test measurement system detects apparent charge below 1 pC is essential. In this paper, we described a PD measurement system which is composed of noise free power source and coupling network, a low-noise amplifier. A

  15. 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.

  16. Voltage-dependent quantum efficiency measurements of amorphous silicon multi-junction mini-modules

    Microsoft Academic Search

    C. J. Hibberd; F. Plyta; C. Monokroussos; M. Bliss; T. R. Betts; R. Gottschalg

    2011-01-01

    Multi-junction solar cells have the potential to provide higher efficiencies than single junction devices and to reduce the impact of Staebler–Wronski degradation on amorphous silicon (a-Si) devices. They could, therefore, reduce the cost of solar electricity. However, their characterization presents additional challenges over that of single junction devices. Achieving acceptable accuracy of any current–voltage calibration requires correction of the current–voltage

  17. EE 210: CIRCUITS AND DEVICES LAB #3: VOLTAGE AND CURRENT MEASUREMENTS

    E-print Network

    Lozano-Nieto, Albert

    voltage source. Set the voltage to 0 Volts. 2. Set up the DMM as a DC ammeter: a. Insert one banana plug of a black, banana-to-banana cable into the COM socket of the DMM. b. Insert the banana plug of a red, banana output of the power supply to using the black, banana-to-banana cable. b. Attach the clip of the red

  18. Electrode effects of a cellulose-based electro-active paper energy harvester

    NASA Astrophysics Data System (ADS)

    Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan; Kim, Joo-Hyung

    2014-07-01

    The possibility of cellulose-based electro-active paper (EAPap) as a vibrational energy transducer was investigated in this paper. Thin cellulose EAPap film specimens were prepared by the regenerating process. Three different metal electrodes of gold, silver and aluminum were deposited on a 50 × 50 mm2 cellulose film using a thermal evaporator. An aluminum cantilever beam was used as a vibrational bender and EAPap was attached close to the root of the cantilever beam. The voltage output of the EAPap was measured under harmonic base excitation of the cantilever beam. The EAPap with aluminum electrode provided the largest open circuit voltage output compared to those with gold or silver electrodes. The output voltages of the EAPap increased linearly with increase of the area of the electrodes. The output voltages also increased with increasing input acceleration but became saturated at a certain magnitude. From the experimental results, we conclude that EAPap with metal electrodes can be used as a flexible energy harvesting transducer by external mechanical stress, and the output voltage is related to the electrode material due to its work function.

  19. Transient Voltage Decoupling Elements

    Microsoft Academic Search

    J. E. Gruber

    1968-01-01

    Premature and inexact timing of thyratron generators may occur during parallel operation of capacitor discharge circuits. Voltage transients which enter the trigger circuits can be eliminated by decoupling spark gaps. A simple, two electrode, spark gap with corona illumination is described. The low jitter of this gap allows its insertion in the output line of a 15 kV thyratron generator

  20. Direct measurement of Cu(II) aq in seawater at pH 8 with the jalpaite ion-selective electrode

    Microsoft Academic Search

    Alberto Zirino; David A. VanderWeele; Stuart L Belli; Roland DeMarco; Denis J Mackey

    1998-01-01

    The variability of measurement of the pCu of seawater at pH 8 was studied using up to 5 similar Orion 90-24, jalpaite-based electrodes. Large variability (ca. 1 pCu unit) among the values yielded by the individual electrodes was observed when the electrodes were stored in artificial seawater and exposed to light including sunlight. This variability is in agreement with mechanisms

  1. 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.

  2. 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.

  3. Positive electrode materials with high operating voltage for lithium batteries: LiCr yMn 2 ? yO 4 (0 ? y ? 1)

    Microsoft Academic Search

    C. Sigala; D. Guyomard; A. Verbaere; Y. Piffard; M. Tournoux

    1995-01-01

    Reversible lithium deintercalation of chromium-substituted spinel manganese oxides LiCryMn2 ? yO4 (0 ? y ? 1) in the voltage range 3.4–5.4 V versus Li, occurs in two main steps for 0 < y < 1: one at about 4.9 V and the other at about 4 V. The 4.9 V process capacity increases with the chromium content while the 4

  4. Near-Electrode Imager

    SciTech Connect

    Rathke, Jerome W.; Klingler, Robert J.; Woelk, Klaus; Gerald, Rex E.,II

    1999-05-01

    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 use the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

  5. 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.

  6. Nonequilibrium Thermodynamics of Porous Electrodes

    E-print Network

    Ferguson, Todd Richard

    We reformulate and extend porous electrode theory for non-ideal active materials, including those capable of phase transformations. Using principles of non-equilibrium thermodynamics, we relate the cell voltage, ionic ...

  7. The differing behavior of electrosurgical devices made of various electrode materials operating under plasma conditions

    NASA Astrophysics Data System (ADS)

    Stalder, K. R.; Ryan, T. P.; Gaspredes, J.; Woloszko, J.

    2015-03-01

    Coblation® is an electrosurgical technology which employs electrically-excited electrodes in the presence of saline solution to produce a localized and ionized plasma that can cut, ablate, and otherwise treat tissues for many different surgical needs. To improve our understanding of how Coblation plasmas develop from devices made from different electrode materials we describe several experiments designed to elucidate material effects. Initial experiments studied simple, noncommercial cylindrical electrode test devices operating in buffered isotonic saline without applied suction. The applied RF voltage, approximately 300 V RMS, was sufficient to form glow discharges around the active electrodes. The devices exhibited significantly different operating characteristics, which we ascribe to the differing oxidation tendencies and other physical properties of the electrode materials. Parameters measured include RMS voltage and current, instantaneous voltage and current, temporally-resolved light emission and optical emission spectra, and electrode mass-loss measurements. We correlate these measured properties with some of the bulk characteristics of the electrode materials such as work functions, standard reduction potentials and sputter yields.

  8. Effect of electrode configuration and electronic conductivity on current density distribution measurements in PEM fuel cells

    E-print Network

    Natarajan, Dilip; Van Nguyen, Trung

    2004-09-03

    of commercially available gas diffusion layers. Both galvanostatic and potentiostatic discharge modes were employed. Irrespective of the type of gas diffusion layer, when a common electrode was employed, significant performance variations were encountered between...

  9. 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.

  10. Kinetic Electrode Reactions in Silver Electrodeposition Using a Multipulse Current Measurement

    Microsoft Academic Search

    M. Saitouz

    Silver and silver alloy deposition in various electrolytes 1-5 have attracted scientific and technological interest. However, there have been very few reports on the kinetics of electrode reactions in silver electrodeposition. In particular, the kinetic constant, the ex- change current density, and the double-layer capacitance in the ferrocyanide-thiocyanate electrolytes, which characterize the kinet- ics of the electrode reactions in silver

  11. Eight electrode optical readout gap

    DOEpatents

    Boettcher, Gordon E. (Albuquerque, NM); Crain, Robert W. (Albuquerque, NM)

    1985-01-01

    A protective device for a plurality of electrical circuits includes a pluity of isolated electrodes forming a gap with a common electrode. An output signal, electrically isolated from the circuits being monitored, is obtained by a photosensor viewing the discharge gap through an optical window. Radioactive stabilization of discharge characteristics is provided for slowly changing voltages and carbon tipped dynamic starters provide desirable discharge characteristics for rapidly varying voltages. A hydrogen permeation barrier is provided on external surfaces of the device.

  12. 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.

  13. Noninvasive measurement of torque development in the rat foot: measurement setup and results from stimulation of the sciatic nerve with polyimide-based cuff electrodes

    Microsoft Academic Search

    Thomas Stieglitz; Martin Schuettler; Andreas Schneider; Elena Valderrama; Xavier Navarro

    2003-01-01

    In neural rehabilitation, selective activation of muscles after electrical stimulation is mandatory for control of paralyzed limbs. For an evaluation of electrode selectivity, a setup to noninvasively measure the force development after electrical stimulation in the rat foot was developed. The setup was designed in accordance to the anatomical features of the rat model to test the isometric torque development

  14. Measurements of stray antenna capacitance in the STEREO\\/WAVES instrument: Comparison of the measured voltage spectrum with an antenna electron shot noise model

    Microsoft Academic Search

    I. Zouganelis; M. Maksimovic; N. Meyer-Vernet; S. D. Bale; J. P. Eastwood; A. Zaslavsky; M. Dekkali; K. Goetz; M. L. Kaiser

    2010-01-01

    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

  15. Electrode measurements of the oxidation reduction potential in the Gotland Deep using a moored profiling instrumentation

    NASA Astrophysics Data System (ADS)

    Meyer, David; Prien, Ralf D.; Dellwig, Olaf; Waniek, Joanna J.; Schulz–Bull, Detlef E.

    2014-03-01

    The Gotland Deep Environmental Sampling Station (GODESS) operating between 30 m and 185 m was used to assess the variation of in situ redox potential (Eh) in the stratified water column of the central Baltic Sea, for a period of 56 days (November 2010-January 2011). The aim of this study was to acquire in-depth understanding of redox variations with the overall objective to identify the processes controlling Eh. At an interval of 8 h basic hydro-physical parameters were registered, including the oxidation-reduction potential, dissolved oxygen, chlorophyll a fluorescence, turbidity, temperature and conductivity. In total 170 profiles of all parameters were obtained. The measured Eh (with respect to standard hydrogen electrode, SHE) ranged from -0.055 V to 0.167 V. After temperature and pH correction of the standard reduction potentials, a comparison of the measured Eh with that calculated for the particular redox couples was carried out by applying the Nernst-equation. Furthermore, the concentrations of the most important redox elements such as Fe, Mn, N, O, C and S used for comparison were estimated by using empirical functions or were based on measurements of discrete water samples, taken at the time of deployment and recovery of the mooring. The obtained results reveal that the reduction of Fe(III) and O2 may be the main processes controlling the Eh potential in the Gotland basin. Below the redoxcline the reduction of hematite and then ferric oxyhydroxide could be related to the redox potential and somewhat deeper Fe(III)/Fe(II) was found to be the dominant redox couple. Although mixed potential theory could have been applied, the Fe couples appear to dominate over many other possible redox equilibria. This may be explained by the relatively high exchange current of Fe and by high Fe concentrations (up to 1.5 ?M). Finally, a close correspondence to the Eh potentials measured in the oxic/hypoxic part of the water column was found considering the O2/O2-· and the O2-·/H2O2 couples. This suggests that one-electron transfer reactions determined the Eh under oxic/hypoxic conditions.

  16. 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.

  17. Nanowire electrodes for high-density stimulation and measurement of neural circuits

    PubMed Central

    Robinson, Jacob T.; Jorgolli, Marsela; Park, Hongkun

    2013-01-01

    Brain-machine interfaces (BMIs) that can precisely monitor and control neural activity will likely require new hardware with improved resolution and specificity. New nanofabricated electrodes with feature sizes and densities comparable to neural circuits may lead to such improvements. In this perspective, we review the recent development of vertical nanowire (NW) electrodes that could provide highly parallel single-cell recording and stimulation for future BMIs. We compare the advantages of these devices and discuss some of the technical challenges that must be overcome for this technology to become a platform for next-generation closed-loop BMIs. PMID:23486552

  18. Signal enhancement of electron magnetic circular dichroism by ultra-high-voltage TEM, toward quantitative nano-magnetism measurements.

    PubMed

    Tatsumi, Kazuyoshi; Muto, Shunsuke; Rusz, Ján; Kudo, Tomohiro; Arai, Shigeo

    2014-06-01

    Electron magnetic circular dichroism (EMCD) has been known as the transmission electron microscopy (TEM) counterpart of X-ray magnetic circular dichroism (XMCD). XMCD is already widely used for the characterization of magnetic materials with synchrotron radiation. There have been common difficulties encountered in quantitative analysis of the EMCD signal measured by medium-voltage TEMs, such as a small signal fraction and the low signal-to-noise ratio of the EMCD signal. Theoretical calculations of EMCD considering many-beam dynamical diffraction effects showed improved net magnetic signal fractions at an accelerating voltage of 1 MV compared with 200 kV, which is in agreement with the present experiment. PMID:24503161

  19. Temperature-dependent and bistable current-voltage measurements in zinc porphyrin molecular junctions.

    PubMed

    Saha, Swatilekha; Nicolaï, Adrien; Owens, Jonathan R; Krawicz, Alexandra; Dinolfo, Peter H; Meunier, Vincent; Lewis, Kim M

    2015-05-20

    We report bistability in current-voltage curves from di(PEP)PorZn in an electromigrated molecular junction. Bistability was observed at ±0.3 V at 300 K but did not occur at 4 K. No bistability was identified at 300 K for another porphyrin molecule (di(Xyl)PorZn), where the phenyl-ethnyl-phenyl (PEP) side groups were replaced with a flexible p-xylene. Molecular dynamics simulations show that bistability may be due to conformation changes related to the fluctuation of the dihedral angle surrounding the zinc and/or the rotation of the porphyrin central plane of the molecule. Results suggest that other mechanisms may play a role in the current-voltage characteristics observed. PMID:25919066

  20. Measurement of Superconductive Voltage Drivers up to 25 Gb\\/s\\/ch

    Microsoft Academic Search

    Yoshihito Hashimoto; Hideo Suzuki; Shuichi Nagasawa; Michitaka Maruyama; Kan Fujiwara; Mutsuo Hidaka

    2009-01-01

    We report on demonstrations of a superconductive voltage driver (SVD), which generates non-return-to-zero (NRZ) output with an SFQ pulse input, up to 25 Gb\\/s\\/ch. The NRZ SVD consists of a coding logic, splitters, buffers, sixteen RS flip-flops (RSFFs), and DC-biased serially connected sixteen 2-junction SQUIDs. Each SQUID is magnetically coupled to the storage loop of each RSFF. The coding logic

  1. Design of the Wireless Temperature Measurement Alarming System in the High-Voltage Transformer Substation

    Microsoft Academic Search

    Qiang Gao; Hongli Wang; Huaxiang Wang

    Due to electric power overload and equipment aging, fire and explosion occur at transmission circuitry joints in high-voltage\\u000a transformer substation caused by high temperatures accumulated at these spots. This frequently brings huge financial loss.\\u000a Conventional far-infrared temperature detector is inefficient for its limited precision level and real-time temperature detection\\u000a using fibre optic cable system appears to be too costly. This

  2. Measurements of motionally induced voltage in the coastal zone of the Throat of the White Sea

    Microsoft Academic Search

    N. A. Palshin; L. L. Vanyan; A. M. Poray-Koshits; V. A. Matyushenko; P. Kaikkonen; J. Tiikkainen

    2002-01-01

    The theoretical relationship between non-local motionally induced voltages (MIV) and tidal currents is validated with observations of natural low-frequency electric field at the coast of the Throat of the White Sea (northwestern Russia). The Throat of the White Sea is a strait of 50-km width and about 500-km length with depths varying from 20 to 50 m connecting semi-closed White

  3. 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.

  4. Impedances of electrochemically impregnated nickel electrodes as functions of potential, KOH concentration, and impregnation method

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1989-01-01

    Impedances of fifteen electrodes form each of the four U.S. manufactures were measured at 0.200 V vs. the Hg/HgO reference electrode. This corresponds to a voltage of 1.145 for a Ni/H2 cell. Measurements were also made of a representative sample of these at 0.44 V. At the higher voltage, the impedances were small and very similar, but at the lower voltage there were major differences between manufacturers. Electrodes from the same manufacturers showed only small differences. The impedances of electrodes from two manufacturers were considerably different in 26 percent KOH from those in 31 percent KOH. These preliminary results seen to correlate with the limited data from earlier life testing of cells from these manufacturers. The impedances of cells being tested for Space Station Freedom are being followed, and more impendance measurements of electrodes are being performed as functions of manufacturer, voltage, electrolyte concentration, and cycle history in hopes of finding better correlations of impedance with life.

  5. Current-voltage relationships in the crystalline lens.

    PubMed Central

    Eisenberg, R S; Rae, J L

    1976-01-01

    1. Electrical coupling between the cells of the crystalline lens of the frog eye was studied using two intralenticular micro-electrodes, one to pass current and one to record potential. In most experiments, both electrodes were placed just inside the posterior surface of the lens at a depth of approximately 200 mum from the surface. Step functions of current were applied and the time course of the resulting change in voltage was measured at many different electrode separations. 2. The voltage change has both a fast component, which occurs only locally in the region close to the current passing micro-electrode, and a slow component, which is spatially uniform, independent of distance from the current micro-electrode. 3. This behaviour is predicted by an electrical model of a single large spherical cell, and so that model can be used to analyse our data. 4. The resistivity of the lens 'interior' (both cytoplasm and coupling resistivity) is 625 omega cm; the resistance of the lens 'membrane' is 2751 omega cm2. 5. The data and analysis help to reconcile discrepancies between previous measurements of the electrical properties of the lens and show clearly that there is substantial electrical coupling from cell to cell. The method should allow investigation of the role of electrical coupling in cataract formation in the crystalline lens. PMID:1086902

  6. Effect of the reference electrode size on the ionization instability in the plasma sheath of a small positively biased electrode

    SciTech Connect

    Bliokh, Y. P.; Brodsky, Yu. L.; Chashka, Kh. B.; Felsteiner, J.; Slutsker, Ya. Z. [Department of Physics, Technion, 32000 Haifa (Israel)

    2011-06-01

    It is well known that additional ionization in the vicinity of a positively biased electrode immersed into a weakly ionized plasma is responsible for a hysteresis in the electrode current-voltage characteristics and the current self-oscillations rise. Here we show both experimentally and theoretically that under certain conditions these phenomena cannot be correctly interpreted once considered separately from the reference electrode current-voltage characteristics. It is shown that small electrodes can be separated into three groups according to the relation between the electrode and the reference electrode areas. Each group is characterized by its own dependence of the collected current on the bias voltage.

  7. Electrochemical performance of platinum electrodes within the multi-electrode spiral nerve cuff.

    PubMed

    Rozman, Janez; Pe?lin, Polona; Mehle, Andraž; Šala, Martin

    2014-09-01

    In this study, the electrochemical performance of platinum electrodes within a multi-electrode spiral cuff to be used for selective nerve stimulation was investigated. The original cuff, simplified into a half-cuff, contained a single row of nine electrodes (0.5 × 2 mm) at a distance of 2 mm from its inner surface. Cyclic voltammetry was used to investigate the electrochemical reactions at the electrode-electrolyte interface, to define a potential window within which the electrode could be safely used in selective nerve stimulation, to calculate the charge injection capacity and cathodal charge storage capacity. Voltage transients retrieved during excitation with quasitrapezoidal biphasic current pulses, tested by selective nerve stimulation of the isolated porcine left cervical vagus nerve segment, were used to determine the maximum polarization across the electrode-electrolyte interface and to calculate cathodic charge injection capacity of the electrode. The results show that the most negative and most positive potentials across the electrode-electrolyte interface reached -0.54 and 0.59 V; these did not exceed the safe potential limits for water electrolysis. Furthermore, the time integral of the cathodic current by cyclic voltammetry measured over the potential range of water electrolysis, actually representing the cathodal charge storage capacity, was approximately -4 mC cm(-2). The charge injection capacity, representing the maximum charge density injected in a current stimulation pulse, using only reversible processes, however, was around 75 µC cm(-2). In conclusion, both, the tested stimulation pulse and electrode are suitable for efficient and safe selective nerve stimulation. PMID:24938675

  8. Transient Analysis of a Porous Electrode Sheba Devan,a,

    E-print Network

    Subramanian, Venkat

    Transient Analysis of a Porous Electrode Sheba Devan,a, * Venkat R. Subramanian,b, ** and Ralph E for the voltage response including the transient voltage for a simple i.e., no concentration gradients porous electrode model subject to a sinusoidal input current density. The transient voltage response as a function

  9. Direct subnanosecond voltage monitors

    SciTech Connect

    Barth, J.E.; Sajeant, W.J.

    1981-01-01

    Advanced system development in the subnanosecond time frame increasingly demands high-resolution voltage measurements for both single-shot and repetitive operation. Voltage monitors having capabilities up to the hundred kilovolt level have been developed for direct measurements in discrete and transmission line geometries. Resolutions of 100 ps at 100 kV to 30 ps at 20 kV have been achieved. Detailed test data is presented and ultimate voltage scaling limits are discussed.

  10. [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

  11. Amplifier for measuring low-level signals in the presence of high common mode voltage

    NASA Technical Reports Server (NTRS)

    Lukens, F. E. (inventor)

    1985-01-01

    A high common mode rejection differential amplifier wherein two serially arranged Darlington amplifier stages are employed and any common mode voltage is divided between them by a resistance network. The input to the first Darlington amplifier stage is coupled to a signal input resistor via an amplifier which isolates the input and presents a high impedance across this resistor. The output of the second Darlington stage is transposed in scale via an amplifier stage which has its input a biasing circuit which effects a finite biasing of the two Darlington amplifier stages.

  12. 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

  13. 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.

  14. Thermo- and photoinduced voltages in Ag heterodimensional junctions

    SciTech Connect

    Xu Jia; Sun Jialin; Zhu Jialin [Department of Physics and Key Lab of Atomic and Molecular Nanoscience of Education Ministry, Tsinghua University, Beijing 100084 (China)

    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.

  15. 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

  16. 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.

  17. Standard deviation of the mean and other time series properties of voltages measured with a digital lock-in amplifier

    NASA Astrophysics Data System (ADS)

    Witt, Thomas J.; Fletcher, N. E.

    2010-10-01

    We investigate some statistical properties of ac voltages from a white noise source measured with a digital lock-in amplifier equipped with finite impulse response output filters which introduce correlations between successive voltage values. The main goal of this work is to propose simple solutions to account for correlations when calculating the standard deviation of the mean (SDM) for a sequence of measurement data acquired using such an instrument. The problem is treated by time series analysis based on a moving average model of the filtering process. Theoretical expressions are derived for the power spectral density (PSD), the autocorrelation function, the equivalent noise bandwidth and the Allan variance; all are related to the SDM. At most three parameters suffice to specify any of the above quantities: the filter time constant, the time between successive measurements (both set by the lock-in operator) and the PSD of the white noise input, h0. Our white noise source is a resistor so that the PSD is easily calculated; there are no free parameters. Theoretical expressions are checked against their respective sample estimates and, with the exception of two of the bandwidth estimates, agreement to within 11% or better is found.

  18. Calibration of bridge-, charge- and voltage amplifiers for dynamic measurement applications

    NASA Astrophysics Data System (ADS)

    Klaus, Leonard; Bruns, Thomas; Volkers, Henrik

    2015-02-01

    Measuring amplifiers are used for transducer output signal conditioning in many dynamic measurement applications. For a traceable measurement, a calibration of all components of the measuring chain—and therefore of the conditioning amplifiers, too—is mandatory. In this paper methods for a dynamic calibration of different types of conditioning amplifiers are presented. Measurement uncertainties and calibration results for typical amplifiers are discussed.

  19. Modeling, fabrication and demonstration of an electrostatic actuator with a coplanar pre-charged electrode

    NASA Astrophysics Data System (ADS)

    Yang, Hyun-Ho; Choi, Dong-Hoon; Oen Lee, Jeong; Yoon, Jun-Bo

    2011-08-01

    We present the modeling, fabrication and measurement results of a novel electrostatic actuator with a coplanar pre-charged electrode. Different from the conventional electrostatic actuator, the pull-in voltage of the proposed actuator can be freely controlled even after fabrication by inducing charges prior to use in the auxiliary electrode right next to the actuation electrode. To investigate the static and dynamic characteristics of the proposed actuator, analytical models were first developed on the basis of a parallel-plate capacitor model. We then successfully designed, fabricated, and evaluated a micro-switch with a fixed-fixed beam and a coplanar pre-charged electrode. By properly introducing a dimple structure, the pull-in voltage of the fabricated micro-switch was reduced from 71.2 V to 6.8 V when pre-charged by 58.8 V. The resonant frequency of the fabricated micro-switch was 84.8% of the initial resonant frequency when the reduced pull-in voltage of the device was half of the original pull-in voltage. These measurement results were compared with those from the analytical models and FEM simulation, showing deviations of less than 12%. This work can favorably be adapted and used in designing an electrostatic micro-switch since the proposed switch can remarkably reduce the pull-in voltage as desired without notable performance degradation.

  20. 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

  1. 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.

  2. Wide-aperture plasma-electrode pockels cell

    SciTech Connect

    Andreev, N. F.; Babin, A. A.; Davydov, V. S.; Matveev, A. Z. [Russian Academy of Sciences, Institute of Applied Physics (Russian Federation); Garanin, S. G.; Dolgopolov, Yu. V.; Kulikov, S. M.; Sukharev, S. A.; Tyutin, S. V. [All-Russian Federal Nuclear Center (VNIIEF) (Russian Federation)

    2011-12-15

    The results of experimental investigations of wide-aperture (100 Multiplication-Sign 100 mm) plasma-electrode Pockels are presented. Time characteristics, contrast, transmission factor, and optical uniformity of the cell are measured. It has been found that the half-wave effective voltage of the cell is 10 kV, the duration of the transmission window can vary from 250 to 550 ns, its leading and trailing edges are 40-50 and 70-100 ns in duration, respectively, and the time of the cell plasma electrode formation is 40 {+-} 5 ns.

  3. Electrode polarization measurements in the Fe|SrCe 0.95Yb 0.05O 2.975|Au proton conducting solid electrolyte cell

    Microsoft Academic Search

    G. Pekridis; K. Kalimeri; N. Kaklidis; C. Athanasiou; G. Marnellos

    2007-01-01

    The effect of hydrogen partial pressure (1.3–5.8 kPa) and cell temperature (600–800 °C) on the kinetics and mechanism of the charge transfer electrode reaction taking place at the three phase boundary H2–Fe–SCY (SCY=SrCe0.95Yb0.05O2.975), was thoroughly examined by performing electrode polarization measurements. A three electrode single chamber proton conducting solid electrolyte cell of the type Fe–SCY–Au, was used in order to conduct the

  4. 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.

  5. Electro-Hydrodynamic (EHD) Thrust Analysis in Wire-Cylinder Electrode Arrangement

    NASA Astrophysics Data System (ADS)

    Konstantinos, N. Kiousis; Antonios, X. Moronis; Wolf, G. Fruh

    2014-04-01

    The thrust generation by electro-hydrodynamic (EHD) effect has been studied for a wire-cylinder arrangement under high DC voltage. Series of measurements have been conducted in order to determine the relationship between generated thrust and corona discharge current, as well as its dependence on geometrical characteristics of the electrodes, e.g. electrode gap, wire and cylinder radii. The experimental investigation has shown a linear relationship between the generated thrust and the discharge current, while parametric analysis showed that increased electrode gap and emitter radius reduces the thrust. On the other hand, large gaps favor the thrust per unit power ratio.

  6. Nonlinear high voltage transmission line for transversely excited CO{sub 2} lasers

    SciTech Connect

    Ishi, Akira; Yasuoka, Koichi; Tamagawa, Tohru [Toshiba Corp., Kanagawa (Japan)] [and others

    1995-12-31

    A high voltage Pulse with the risetime less than a few hundreds nanoseconds and the amplitude of several tens kilovolts is required to establish stable glow discharge excitation in high power pulsed gas lasers. To make the high voltage pulse fast, we have developed a nonlinear high voltage transmission line for transversely excited CO{sub 2} lasers. Fig.1 shows the electrical circuit of switching unit, pulse sharpening unit with nonlinear high voltage transmission line and discharge electrodes for TE-CO{sub 2} laser. The nonlinear high voltage transmission line is a 15-step LC ladder circuit that consists of linear inductors (L=6 {mu}H) and nonlinear BaTiO{sub 3} capacitors. Fig.2 shows a capacitance dependence on applied voltages. If an LC ladder circuit is constructed using a capacitor with the characteristics, the transmission velocity is fast at the high-voltage section and is slow at the low-voltage section. High voltage pulse with slow risetime is expected to be sharpen. The voltage and the current waveforms of the discharge measured at the point {open_quotes}c{close_quotes}. The risetime of 1{mu}s of the input voltage pulse was compressed to less than 200 ns at the output terminal of the LC ladder circuit and the outout pulse was applied to the discharge gap of the laser.

  7. Self-discharge of LiMnâOâ\\/C Li-ion cells in their discharged state: Understanding by means of three-electrode measurements

    Microsoft Academic Search

    A. Blyr; C. Sigala; J. M. Tarascon; G. Amatucci; D. Guyomard; Y. Chabre

    1998-01-01

    The potential distribution through plastic Li-ion cells during electrochemical testing was monitored by means of three- or four-electrode measurements in order to determine the origin of the poor electrochemical performance (namely, premature cell failure, poor storage performance in the discharged state) of LiMnâOâ\\/C Li-ion cells encountered at 55 C. Several approaches to insert reliably one or two reference electrodes that

  8. Use of Multi-Functional Flexible Micro-Sensors for in situ Measurement of Temperature, Voltage and Fuel Flow in a Proton Exchange Membrane Fuel Cell

    PubMed Central

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 ?m-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased. PMID:22163545

  9. Use of multi-functional flexible micro-sensors for in situ measurement of temperature, voltage and fuel flow in a proton exchange membrane fuel cell.

    PubMed

    Lee, Chi-Yuan; Chan, Pin-Cheng; Lee, Chung-Ju

    2010-01-01

    Temperature, voltage and fuel flow distribution all contribute considerably to fuel cell performance. Conventional methods cannot accurately determine parameter changes inside a fuel cell. This investigation developed flexible and multi-functional micro sensors on a 40 ?m-thick stainless steel foil substrate by using micro-electro-mechanical systems (MEMS) and embedded them in a proton exchange membrane fuel cell (PEMFC) to measure the temperature, voltage and flow. Users can monitor and control in situ the temperature, voltage and fuel flow distribution in the cell. Thereby, both fuel cell performance and lifetime can be increased. PMID:22163545

  10. 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

  11. Accurate on wafer measurement of phase and amplitude of the spectral components of incident and scattered voltage waves at the signal ports of a nonlinear microwave device

    Microsoft Academic Search

    Jan Verspecht; Peter Debie; Alain Barel; Luc Martens

    1995-01-01

    A measurement setup and calibration procedure are described allowing the accurate on wafer measurement of phases and amplitudes of the spectral components of incident and scattered voltage waves at the signal ports of a nonlinear microwave device. A comparison is made between measurements performed with the setup and simulations based on a Root-model

  12. Permselectivities of polyelectrolyte electrode coatings as inferred from measurements with incorporated redox probes or concentration cells

    SciTech Connect

    Redepenning, J.; Anson, F.C.

    1987-01-01

    Permselectivities of coatings and membranes prepared from polyanionic Nafion and from a new type of polycationic copolymer were evaluated by two methods. (i) Electroactive couples incorporated in coatings on graphite electrode surfaces served as redox probes whose apparent formal potentials changed as the concentration of supporting electrolyte was varied. The magnitude of those changes allowed the permselectivities of the coating to be surmised. (ii) Thicker layers of the polyelectrolytes were used as membranes to separate supporting electrolyte solutions of differing concentrations. The potential difference between reference electrodes placed on either side of the membrane allowed the permselectivities of the membranes to be judged. Both of the methods indicated nearly ideal permselectivity of Nafion coatings and membranes at supporting electrolyte concentrations below ca. 2 M. Ideal permselectivity continued to be registered for a Nafion membranes by the redox probe method even after the membrane had been punctured so that the bulk cation transference number was far from unity. For the polycationic copolymer, both methods indicated increasing deviations from ideal anion permselectivity as the concentration of the supporting electrolyte was increased. Interpretations and some consequences of the observations are presented.

  13. A Microfluidic Bioreactor With Integrated Transepithelial Electrical Resistance (TEER) Measurement Electrodes for Evaluation of Renal Epithelial Cells

    PubMed Central

    Ferrell, Nicholas; Desai, Ravi R.; Fleischman, Aaron J.; Roy, Shuvo; Humes, H. David; Fissell, William H.

    2014-01-01

    We have developed a bilayer microfluidic system with integrated transepithelial electrical resistance (TEER) measurement electrodes to evaluate kidney epithelial cells under physiologically relevant fluid flow conditions. The bioreactor consists of apical and basolateral fluidic chambers connected via a transparent microporous membrane. The top chamber contains microfluidic channels to perfuse the apical surface of the cells. The bottom chamber acts as a reservoir for transport across the cell layer and provides support for the membrane. TEER electrodes were integrated into the device to monitor cell growth and evaluate cell–cell tight junction integrity. Immunofluorescence staining was performed within the microchannels for ZO-1 tight junction protein and acetylated ?-tubulin (primary cilia) using human renal epithelial cells (HREC) and MDCK cells. HREC were stained for cytoskeletal F-actin and exhibited disassembly of cytosolic F-actin stress fibers when exposed to shear stress. TEER was monitored over time under normal culture conditions and after disruption of the tight junctions using low Ca2+ medium. The transport rate of a fluorescently labeled tracer molecule (FITC-inulin) was measured before and after Ca2+ switch and a decrease in TEER corresponded with a large increase in paracellular inulin transport. This bioreactor design provides an instrumented platform with physiologically meaningful flow conditions to study various epithelial cell transport processes. PMID:20552673

  14. Low-voltage-tunable nanobeam lasers immersed in liquid crystals.

    PubMed

    Kim, Sejeong; Kim, Hwi-Min; Son, Jaehyun; Kim, Yun-Ho; Ok, Jong Min; Kim, Ki Soo; Jung, Hee-Tae; Min, Bumki; Lee, Yong-Hee

    2014-12-15

    A low-voltage-tunable one-dimensional nanobeam laser is realized by employing lithographically defined lateral electrodes. An InGaAsP nanobeam with a sub-micrometer width is transfer-printed in the middle of two electrodes using a polydimethylsiloxane stamp. Spectral tuning is achieved by controlling the molecular alignment of the surrounding liquid crystals (LCs). From ?m-scale-gap structures, a total wavelength shift that exceed 6 nm is observed at a low voltage of less than 10 V. A measured spectral tuning rate of 0.87 nm/V, which is the largest value ever reported to our knowledge among LC-tuned photonic crystal lasers, was also noted. PMID:25607018

  15. Finite-Element and Genetic Algorithm Design of Multi-segmented Electro-optic Sensor for Pulsed High-Voltage Measurement

    Microsoft Academic Search

    Angelo Passaro; Jonas Rubini Júnior; Nancy Mieko Abe; Milton Sasaki; Josemir Coelho Santos

    In the last few years, innovative electro-optic sensors, such as Optical Voltage and Optical Current Transformers, have been developed and used for high-voltage and high-current measurements in power systems. This kind of sensor presents fast transitory response, no susceptibility to electromagnetic interference high signal\\/noise ratio, reduced size and weight, and provides electric isolation. These devices are based on optical modulator.

  16. Needle electrode-based electromechanical reshaping of rabbit septal cartilage: a systematic evaluation.

    PubMed

    Wu, Edward C; Protsenko, Dmitriy E; Khan, Adam Z; Dubin, Sterling; Karimi, Koohyar; Wong, Brian J F

    2011-08-01

    Electromechanical reshaping (EMR) provides a means of producing shape change in cartilage by initiating oxidation-reduction reactions in mechanically deformed specimens. This study evaluates the effect of voltage and application time on specimen shape change using needle electrodes. Rabbit septal cartilage specimens (20 x 8 x 1 mm, n = 200) were bent 90 degrees in a precision-machined plastic jig. Optimal electrode placement and the range of applied voltages were estimated using numerical modeling of the initial electric field within the cartilage sample. A geometric configuration of three platinum needle electrodes 2 mm apart from each other and inserted 6 mm from the bend axis on opposite ends was selected. One row of electrodes served as the anode and the other as the cathode. Constant voltage was applied at 1, 2, 4, 6, and 8 V for 1, 2, and 4 minutes, followed by rehydration in phosphate buffered saline. Samples were then removed from the jig and bend angle was measured. In accordance with previous studies, bend angle increased with increasing voltage and application time. Below a voltage threshold of 4 V, 4 minutes, no clinically significant reshaping was observed. The maximum bend angle obtained was 35.7 ± 1.7 º at 8 V, 4 minutes. PMID:21606017

  17. In situ layer-by-layer film formation kinetics under an applied voltage measured by optical waveguide lightmode spectroscopy.

    PubMed

    Ngankam, A Pascal; Van Tassel, Paul R

    2005-06-21

    Layer-by-layer (LbL) thin film assembly occurs via the alternate adsorption of positively and negatively charged macromolecular species. We investigate here the control of LbL film growth through the electric potential of the underlying substrate. We employ optical waveguide lightmode spectroscopy (OWLS) to obtain in situ kinetic measurements of poly(allylamine hydrochloride)/poly(sodium 4-styrenesulfonate) (PAH/PSS) and poly(L-lysine)/dextran sulfate (PLL/DXS) multilayer film formation in the presence of an applied voltage difference (deltaV) between the adsorbing substrate, an indium tin oxide- (ITO-) coated waveguiding sensor chip, and a parallel platinum counterelectrode. We find initial layer adsorption to be significantly enhanced by an applied potential for both polyelectrolyte systems: the mass and thickness of (positively charged) PAH and PLL layers on ITO are about 60% and 500% larger, respectively, at deltaV = 2 V than at open circuit potential (OCP), in apparent violation of electrostatics. A kinetic analysis reveals the initial attachment rate constant to decrease with voltage, in agreement with electrostatics. To reconcile these results, we propose a more coiled and loosely bound adsorbed polymer conformation at higher applied potential. Following 10 adsorption steps, the mass and thickness of a PAH/PSS film grown under deltaV = 2 V are about 15% less than those of a comparable film grown under OCP, reflecting a lower degree of complexation between adsorbing polyanions and more highly coiled adsorbed polycations. Following 14 adsorption steps, the mass and thickness of a PLL/DXS film grown under deltaV = 2 V are about 70% greater than those of a comparable film grown under OCP, reflecting the increased charge overcompensation in the initial layer. We find the scaling of film mass () with the number of adsorption steps (n) to be linear in the PAH/PSS system and exponential (i.e., approximately eyn) in the PLL/DXS system, irrespective of applied voltage. We observe to decrease with applied voltage and to exhibit a crossover to a smaller value around n = 5. Extrapolation reveals PLL/DXS multilayer films to be suppressed by increased voltage in the limit of large n: the mass of films grown at OCP and deltaV = 1 V would surpass that of a film grown under deltaV = 2 V at about the 23rd and 18th adsorption steps, respectively. The formation kinetics of PLL/DXS, but not PAH/PSS, change qualitatively under voltage: PLL adsorption is slow to reach a plateau, possibly due to the formation of secondary structure, and a decrease in film mass occurs toward the end of each DXS adsorption step, suggesting spontaneous removal of some PLL/DXS complexes from the film. PMID:15952835

  18. 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.

  19. Chromaticity of synaptic inputs to H1 horizontal cells in carp retina: analysis by voltage-clamp and spectral adaptation

    Microsoft Academic Search

    Masahiro Yamada; John C. Low; Mustafa B. A. Djamgoz

    1992-01-01

    Cone photoreceptor inputs to H1 horizontal cells (H1 HCs) in carp retina were studied by measuring light-modulated currents (IL) to monochromatic stimuli (460, 533, 688 nm) under a voltage-clamp condition. By using double-barrelled micro-electrodes H1 HCs were voltage-clamped whilst perfusing with dopamine to uncouple the cells. The IL of the H1 HCs driven by each cone input was segregated by

  20. Application of reduced graphene oxide and carbon nanotube modified electrodes for measuring the enzymatic activity of alcohol dehydrogenase.

    PubMed

    Wang, Xianlong; Li, Li; Wang, Yanping; Xu, Chongzheng; Zhao, Bo; Yang, Xiaodi

    2013-06-15

    An electrochemical method was developed to measure the enzymatic activity of alcohol dehydrogenase (ADH) by monitoring the amount of reduced nicotinamide adenine dinucleotide (NADH) generated in the catalysed oxidation of ethanol by ADH. The concentration of NADH was determined by amperometric measurements, which recorded the oxidation current of NADH versus time on reduced graphene oxide and functionalised multi-walled carbon nanotube modified electrodes. The initial reaction rates and the apparent Michaelis constants of the enzymatic reaction were obtained in the absence and presence of Al(3+) and nanometre-sized tridecameric aluminium polycationic (nano-Al(13)) species. The results showed that Al(3+) and nano-Al(13) exhibited inhibitory effect on the enzymatic activity of ADH. Fluorescence and circular dichroism spectra indicated the inhibitory effect was likely caused by the conformational changes of ADH and/or NADH induced by Al(3+) and nano-Al(13). PMID:23497876

  1. 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.

  2. 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

  3. Mass-resolved ion energy measurements at both electrodes of a 13.56 MHz plasma in CF4

    NASA Astrophysics Data System (ADS)

    Snijkers, R. J. M. M.; van Sambeek, M. J. M.; Hoppenbrouwers, M. B.; Kroesen, G. M. W.; de Hoog, F. J.

    1996-06-01

    The ion energy distributions (IEDs) at the electrodes in a capacitively coupled 13.56 MHz plasma in CF4 have been measured mass resolved with a Balzers quadrupole in combination with a home-built energy analyzer. Mass-resolved determination offers the possibility to compare the IED of different ions achieved in the same sheath. The IEDs have been determined at both the largest and the smallest electrode. Apart from the IEDs of the CF4 species, the IEDs of ionic species in plasmas in argon and nitrogen also were determined. Apart from the CF4 ionic species CF+3, CF+2, CF+, and F+, CHF+2 ions also are present in the CF4 plasma due to residual water in the reactor. Because the CHF+2 ions are not produced in the sheath and because we do not detect elastically scattered ions, the IEDs of these ions show the typical bimodal distribution for rf plasmas which corresponds to an IED of ions which have not collided in the sheath. From these IEDs we can obtain the sheath characteristics, such as the averaged sheath potential. From the IEDs of CF+n ions one can conclude that, in the sheath of the CF4 plasma, a large number of chemical reactions takes place between the CF+n ions and the neutrals.

  4. 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.

  5. New developments for in situ ultrasonic measurement of transient temperature distributions at the tip of a copper resistance spot weld electrode

    Microsoft Academic Search

    A. C. Karloff; A. M. Chertov; J. Kocimski; P. Kustron; R. Gr. Maev

    2010-01-01

    This paper presents the new development of a joint thermal simulation and ultrasonic time of flight (TOF) measurement technique for the In situ measurement of transient temperature distributions. A coupled finite element model, using conductive media DC and heat transfer by conduction, was used to simulate the expected transient temperature distributions within the copper electrode during welding. Simulated temperature distributions

  6. 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.

  7. Measurement of Sparkover Voltage and Time Lag Characteristics in CF3I-N2 and CF3I-Air Gas Mixtures by using Steep-front Square Voltage

    NASA Astrophysics Data System (ADS)

    Toyota, Hiroyuki; Matsuoka, Shigeyasu; Hidaka, Kunihiko

    A square pulse voltage is useful for studying electrical discharge physics or very fast transient overvoltage issues. This paper describes sparkover voltages and time lag (V-t) characteristics of CF3I gas, which has very low environmental effects and high dielectric strength, and its mixtures with nitrogen gas or air in a very short time range below a microsecond. They are measured by using a steep-front square voltage with a rise time of 16 nanoseconds and a peak value of 200 kilovolts. Pure CF3I gas has 20 % higher dielectric strength than SF6 gas. V-t characteristics of CF3I-N2 or CF3I-air gas mixtures, which contain 60% CF3I gas, are equivalent to those of pure SF6 gas at the same total pressure. A quantitative evaluation of V-t characteristics by the equal area criterion is also performed. The equal area parameter which is obtained by applying a voltage enough high to make the formative time lag dominant should be chosen.

  8. Voltage Drop

    NSDL National Science Digital Library

    The first site with information on voltage drop is provided by Power and System Innovations on their Frequently Asked Questions: Voltage Drop (1) page. Visitors can read what voltage drop is, what causes it, what happens as a result of it, and what the maximum recommended voltage drop is. The second site, Basics of Electricity (2), is part of General Electric's Lighting for Business Web site. Through descriptions and illustrations, the site explains what voltage drop is and gives examples of how it is calculated using Ohm's law. The next site is a lab worksheet that is part of a class from the Electrical and Computer Engineering Department of Montana State University called Voltage Drop in Cables (3). The objective of the lesson is to determine the internal resistance of an extension cord and choose the proper wire size for a particular application. Students are given an explanation of the procedure and a number of questions to answer related to the exercise. The Oregon Building Congress offers the Lesson Plans (4) Web site and the downloadable Voltage Drop educational activity. The lesson, which is suggested to be contained within a unit on formulas and solving literal equations, explores the concept of voltage drop that is encountered in basic wiring. The fifth site entitled Explanation of Voltage Drop in a Series Circuit (5) is offered by the Horizons Electronic Lesson Plan Resource. The page describes voltage drop as an electronic concept, gives a formula determining voltage drop, provides a schematic that helps illustrate the concept, and offers a quiz and answer sheet. Next, from electrician.com, is the online Voltage Drop Calculator (6). Users input the type and size of wire being used, the voltage and phase, circuit length, and amp load to calculate voltage drop and several other parameters. The seventh site, entitled The Hazards of Voltage Drop (7), is provided within the Electrical Construction Maintenance Web site. The page describes how electrical equipment can overheat or even power down if it operates below its voltage rating. It also provides a thorough explanation of how to determine the load's operating voltage. The last site, maintained by Williamson Labs (8), is a comprehensive learning site called Elementary Electricity. Visitors will find a wealth of information here, including fun descriptions, graphics, and animations on all aspects of electricity including voltage drop.

  9. 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.

  10. 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

  11. An On-Chip NBTI Sensor for Measuring PMOS Threshold Voltage Degradation

    E-print Network

    Kim, Chris H.

    or passivation phase, where H atoms diffuse back towards the oxide/silicon interface and anneal the broken Si the characteristics of this mechanism, accurate and efficient means of measuring its effects must be explored), especially at high temperatures. The degradation in Vtp has a power­law dependency on time, and is a function

  12. Study on voltage biasing technique for spectral response measurement of multi-junction solar cell

    Microsoft Academic Search

    Duogang Ran; Sixiang Zhang; Jian Zhang; Xianfeng Zhang; Feng Wan

    2007-01-01

    Multi-junction solar cell (MJ) has been paid more attention for space and terrestrial concentrator system applications because of more efficiency has achieved. The spectral response (SR) of MJ is an important characteristic for technique optimization or performance evaluation. Measurement of SR of MJ cell is quite more difficult than that of single-junction solar cell (SJ) because a complicated light biasing

  13. Using voltage-driven model to correlate GTEM cell and anechoic chamber measurement

    Microsoft Academic Search

    Bo Zhao; Min Zhao; Daosheng Chen

    2012-01-01

    To improve the accuracy of the GTEM cell applied in radiated EMI measurement, an EMI noise extraction model and the error compensation method based on variance analysis are proposed. High moments were employed to compare the similarity of the two test curves between the GTEM cell after calibration and the standard test. The experimental results for a PCB using the

  14. A Method for Measuring the Volume of Transdermally Extracted Interstitial Fluid by a Three-Electrode Skin Resistance Sensor

    PubMed Central

    Li, Dachao; Wang, Ridong; Yu, Haixia; Li, Guoqing; Sun, Yue; Liang, Wenshuai; Xu, Kexin

    2014-01-01

    It is difficult to accurately measure the volume of transdermally extracted interstitial fluid (ISF), which is important for improving blood glucose prediction accuracy. Skin resistance, which is a good indicator of skin permeability, can be used to determine the volume of extracted ISF. However, it is a challenge to realize in vivo longitudinal skin resistance measurements of microareas. In this study, a three-electrode sensor was presented for measuring single-point skin resistance in vivo, and a method for determining the volume of transdermally extracted ISF using this sensor was proposed. Skin resistance was measured under static and dynamic conditions. The correlation between the skin resistance and the permeation rate of transdermally extracted ISF was proven. The volume of transdermally extracted ISF was determined using skin resistance. Factors affecting the volume prediction accuracy of transdermally extracted ISF were discussed. This method is expected to improve the accuracy of blood glucose prediction, and is of great significance for the clinical application of minimally invasive blood glucose measurement. PMID:24759111

  15. Development of membrane-based biosensors: Measurement of current from photocycling bacteriorhodopsin on patch clamp electrodes

    SciTech Connect

    Yager, P.

    1988-01-01

    Our initial work toward developing membrane protein-based biosensors has involved use of bacteriorhodopsin (BR) as a model membrane protein. BR was incorporated into liposomes of a polymerizable lecithin, and was shown to pump protons in response to illumination both before and after polymerization of the lipids. In the work described in this paper, BR was first reincorporated in liposomes of asolectin by consonication with purple membrane. The liposomes, which sustained the function of the protein, were used to form a monolayer at the air-water interface. This monolayer was transferred as a bilayer onto patch electrode. When illuminated with a pulse of 514.5-nm light the lipid/protein patch produced a current spike into the pipette corresponding to events no later than the generation of the 412-nm intermediate, probably caused by pumping of protons across the patch membrane. The experiment demonstrates not only the extreme sensitivity of amperometric detection, but also a small tendency for membrane proteins to preferentially orient in this configuration.

  16. 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

  17. Digital wireless data acquisition system for measurement in high voltage substations

    Microsoft Academic Search

    Y. Wang; F. A. M. Mir; W. H. Siew

    2006-01-01

    This paper describes a new digital wireless data acquisition system that can be used to measure electromagnetic interference (EMI) in power stations or other similar harsh environments. It comprises of a remote acquisition unit (RAU), a wireless data communication network (WDCN) and a PC-based control platform as a front end of the field-distributed-data-acquisition system, RAU captures, digitizes and stores the

  18. Measurement of Antennas and Microwave Components Using Time-Domain Reflectometry of a Voltage Impulse

    Microsoft Academic Search

    Steven McCabe; Jonathan Scott

    2011-01-01

    Band-pass microwave systems such as ultra-wide- bandantennasare traditionallycharacterized inthe frequency-do- main through a vector network analyzer in an anechoic chamber. A recent study proved antennas could be accurately measured in the time-domain using a step-function time-domain reflectometer (TDR), without the need for an anechoic chamber. We propose a new advance in the TDR characterization method. An impulse generator is employed

  19. Time-resolved photoelectrochemical measurements and photovoltaic efficiency of electrochemically self-assembled ZnO-dye electrodes

    NASA Astrophysics Data System (ADS)

    Schlettwein, Derck; Oekermann, Torsten; Tsukasa, Yoshida; Sugiura, Takashi; Minoura, Hideki; Woehrle, Dieter

    2002-02-01

    Dye-modified ZnO thin films were prepared by electrochemically induced crystallization from aqueous mixtures of zinc nitrate and water-soluble dyes. A direct crystallization of semiconductor/ dye composites without heat treatment is seen as a significant advantage of this method. Moreover, characterization of these materials has revealed ordered growth of ZnO crystallites as well as formation of ordered dye assemblies, thus characterizing this method as electrochemical self-assembly. The photoelectrochemical properties of these unique ZnO-dye thin film electrodes were investigated in photocurrent transient measurements in the ms-regime and by steady- state voltammetric measurements. Two sets of electrodes are discussed, employing either metal complexes of tetrasulfophthalocyanines (TSPcMt; Mt = Zn, Al, Si) or the xanthene dye Eosin Y. For aggregates of TSPcMt on ZnO, efficient charge-transfer to the electrolyte is found, leading to low surface charging and low surface recombination of photogenerated holes with electrons from the ZnO, at however, rather low injection efficiencies of electrons into the conduction band of ZnO. This efficiency was higher for adsorbed monomers of TSPcMt leading to a considerably higher quantum efficiency of the photocurrent in spite of increased surface charging and recombination of holes. Higher photocurrents were observed for ZnO sensitized with monomers of Eosin Y caused by both, efficient electron transfer from the dye to ZnO as well as hole transfer from the dye to the electrolyte. Not only dye molecules which were directly accessible from the electrolyte, but also those which were enclosed within matrix cavities proved to be photoelectrochemically active.

  20. 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

  1. Performance enhancement of ITO/oxide/semiconductor MOS-structure silicon solar cells with voltage biasing

    NASA Astrophysics Data System (ADS)

    Ho, Wen-Jeng; Huang, Min-Chun; Lee, Yi-Yu; Hou, Zhong-Fu; Liao, Changn-Jyun

    2014-12-01

    In this study, we demonstrate the photovoltaic performance enhancement of a p-n junction silicon solar cell using a transparent-antireflective ITO/oxide film deposited on the spacing of the front-side finger electrodes and with a DC voltage applied on the ITO-electrode. The depletion width of the p-n junction under the ITO-electrode was induced and extended while the absorbed volume and built-in electric field were also increased when the biasing voltage was increased. The photocurrent and conversion efficiency were increased because more photo-carriers are generated in a larger absorbed volume and because the carriers transported and collected more effectively due to higher biasing voltage effects. Compared to a reference solar cell (which was biased at 0 V), a conversion efficiency enhancement of 26.57% (from 12.42% to 15.72%) and short-circuit current density enhancement of 42.43% (from 29.51 to 42.03 mA/cm2) were obtained as the proposed MOS-structure solar cell biased at 2.5 V. In addition, the capacitance-volt (C-V) measurement was also used to examine the mechanism of photovoltaic performance enhancement due to the depletion width being enlarged by applying a DC voltage on an ITO-electrode.

  2. Using mesoporous carbon electrodes for brackish water desalination.

    PubMed

    Zou, Linda; Li, Lixia; Song, Huaihe; Morris, Gayle

    2008-04-01

    Electrosorptive deionisation is an alternative process to remove salt ions from the brackish water. The porous carbon materials are used as electrodes. When charged in low voltage electric fields, they possess a highly charged surface that induces adsorption of salt ions on the surface. This process is reversible, so the adsorbed salt ions can be desorbed and the electrode can be reused. In the study, an ordered mesoporous carbon (OMC) electrode was developed for electrosorptive desalination. The effects of pore arrangement pattern (ordered and random) and pore size distribution (mesopores and micropores) on the desalination performance was investigated by comparing OMC and activated carbon (AC). It were revealed from X-ray diffraction and N(2) sorption measurements that AC has both micropores and mesopores, whereas ordered mesopores are dominant in OMC. Their performance as potential electrodes to remove salt was evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests at a range of electrolyte concentrations and sweep rates. It is deduced that under the same electrochemical condition the specific capacitance values of OMC electrode (i.e. 133 F/g obtained from CV at a sweep rate of 1 mV/s in 0.1M NaCl solution) are larger than those of AC electrode (107 F/g), suggesting that the former has a higher desalting capacity than the latter. Furthermore, the OMC electrode shows a better rate capacity than the AC electrode. In addition, the desalination capacities were quantified by the batch-mode experiment at low voltage of 1.2V in 25 ppm NaCl solution (50 micros/cm conductivity). It was found that the adsorbed ion amounts of OMC and AC electrodes were 11.6 and 4.3 micromol/g, respectively. The excellent electrosorptive desalination performance of OMC electrode might be not only due to the suitable pore size (average of 3.3 nm) for the propagation of the salt ions, but also due to the ordered mesoporous structure that facilitates desorption of the salt. Based on the results, it was found that the development of an ordered mesoporous structure and the control of the number of micropores are two important strategies for optimising electrode material properties for electrosorptive deionisation. PMID:18222527

  3. A miniature high voltage plasma interaction flight experiment - Project MINX. [for measuring solar cell array parasitic current drain

    NASA Technical Reports Server (NTRS)

    Riley, T. J.; Triner, J. E.; Sater, B. L.; Cohen, D.; Somberg, H.

    1974-01-01

    A miniature high-voltage array was fabricated, incorporating the multi-junction edge illuminated (MJC) cell technique. The array consists of 32 2x2.2 cm MJCs, series connected, capable of 1600 V open circuit at 1 AMO and 1.2 mA short circuit. A solid state, high-voltage relay is connected across each 4-cell subgroup of the array. It was built to test plasma current drain on space systems using high voltage as might occur when a high-voltage solar array is operated from low to synchronous orbit.

  4. 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.

  5. Electrodeposition of Nanoporous Nickel Layers Using Inductive Voltage Pulses

    NASA Astrophysics Data System (ADS)

    Vanags, Martins; Kleperis, Janis; Bajars, Gunars; Nemcevs, Vladimirs

    2013-12-01

    We used inductive voltage pulses for electro-deposition of porous nickel thin film onto steel electrode. Short pulses (tp<1 ?s) with variable amplitude (to ensure electro-deposition current density in region 124-224 A/dm2) were applied to electrode and resulting coating were analyzed with electrochemical and microscopic methods. At lower current densities only smooth nickel coatings growth, while at higher current densities the bubbles appear and porous layer was formed. Electrochemical impedance spectra of smooth and porous layers are measured in deionized water and in 1M KOH solution. The capacity in equivalent scheme is proportional to electrode surface, and from impedance spectra it is calculated that porous layer has 20 times larger active surface comparing to smooth layer (in KOH solution). From electrochemical measurements it is estimated that more efficient hydrogen evolution reaction occurs on electrode with porous nickel layer obtained at 223 A/dm2. It is shown in this work that inductive short pulse method can be used to obtain nano-porous nickel coatings on electrodes for efficient electrolysis cell.

  6. 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.

  7. Design of electrode array for impedance measurement of lesions in arteries

    Microsoft Academic Search

    Sungbo Cho; Hagen Thielecke

    2005-01-01

    Use of impedance catheters can provide additional information about the composition and the morphology of early plaques in arteries. However, for a correct interpretation of the impedance data recorded inside a vessel, the extra-vessel conditions should not influence the measurement results. In this paper, we estimate the influence of the extra-vessel conditions on the impedance measurement of a vessel wall

  8. Voltage and ion current measurements for an ion diode driven by mercury in positive polarity with layered mitl flow

    Microsoft Academic Search

    P. F. Ottinger; R. J. Allen; J. P. Apruzese; D. D. Hinshelwood; S. L. Jackson; D. Murphy; D. Phipps; J. W. Schumer; B. V. Weber; E. C. Young

    2010-01-01

    Summary form only given. For pulsed power machines with an inductive voltage adder (IVA) architecture and a magnetically insulated transmission line (MITL), positive polarity operation results in layered MITL flow as emitted electrons are born at different potentials in each of the adder cells. Because of this layered flow, the usual prediction of the voltage using the Mendel formula is

  9. High-voltage pulsed generator for dynamic fragmentation of rocks

    NASA Astrophysics Data System (ADS)

    Kovalchuk, B. M.; Kharlov, A. V.; Vizir, V. A.; Kumpyak, V. V.; Zorin, V. B.; Kiselev, V. N.

    2010-10-01

    A portable high-voltage (HV) pulsed generator has been designed for rock fragmentation experiments. The generator can be used also for other technological applications. The installation consists of low voltage block, HV block, coaxial transmission line, fragmentation chamber, and control system block. Low voltage block of the generator, consisting of a primary capacitor bank (300 ?F) and a thyristor switch, stores pulse energy and transfers it to the HV block. The primary capacitor bank stores energy of 600 J at the maximum charging voltage of 2 kV. HV block includes HV pulsed step up transformer, HV capacitive storage, and two electrode gas switch. The following technical parameters of the generator were achieved: output voltage up to 300 kV, voltage rise time of ˜50 ns, current amplitude of ˜6 kA with the 40 ? active load, and ˜20 kA in a rock fragmentation regime (with discharge in a rock-water mixture). Typical operation regime is a burst of 1000 pulses with a frequency of 10 Hz. The operation process can be controlled within a wide range of parameters. The entire installation (generator, transmission line, treatment chamber, and measuring probes) is designed like a continuous Faraday's cage (complete shielding) to exclude external electromagnetic perturbations.

  10. Biased electrodes for SOL control in NSTX

    Microsoft Academic Search

    S. J. Zweben; R. J. Maqueda; A. L. Roquemore; C. E. Bush; R. Kaita; R. J. Marsala; Y. Raitses; R. H. Cohen; D. D. Ryutov

    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 EpolxB flow. When the applied voltage between electrodes was ±90V, the density between these electrodes increased by a factor of 3–10 over a radial width of ?4cm. Thus a local control of the SOL

  11. Dielectric elastomer actuators with elastomeric electrodes

    NASA Astrophysics Data System (ADS)

    Bozlar, Michael; Punckt, Christian; Korkut, Sibel; Zhu, Jian; Chiang Foo, Choon; Suo, Zhigang; Aksay, Ilhan A.

    2012-08-01

    For many applications of dielectric elastomer actuators, it is desirable to replace the carbon-grease electrodes with stretchable, solid-state electrodes. Here, we attach thin layers of a conducting silicone elastomer to prestrained films of an acrylic dielectric elastomer and achieve voltage-actuated areal strains over 70%. The influence of the stiffness of the electrodes and the prestrain of the dielectric films is studied experimentally and theoretically.

  12. Conductive Additive Carbon for High Voltage Electrochemical Double Layer Capacitors (EDLCs)

    Microsoft Academic Search

    M. S. Michael; Y. R. Shah; R. Vimala; S. R. S. Prabaharan

    2002-01-01

    Supercapacitors of high voltage, 2.5-3.5V have been fabricated with carbon electrodes namely KS6, SFG6 and MB15, which are commonly used as conductive additives in lithium-ion batteries, and their performance has been evaluated by galvanostatic charge\\/discharge, cyclic voltammetry, and constant power load. Electrochemical impedance spectroscopic (EIS) measurements have been carried out to measure the various parameters such as ESR (equivalent series

  13. 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 ...

  14. Measurement of polarization charge density at the interface between PET-film and electrode with a thin air layer by PEA method

    Microsoft Academic Search

    Kazunori Kadowaki; Sakae Nishimoto; Isamu Kitani

    2000-01-01

    Surface charge density on a 25 ?m PET film due to polarization was measured by a PEA method. In order to separate a pressure wave due to charges on the film from that due to charges on the adjacent electrode, a very thin air layer less than 1 ?m at the interface was utilized as an acoustic barrier. A linear

  15. Using temperature, voltage, and\\/or speed measurements to improve trending of induction motor RMS currents in process control and diagnostics

    Microsoft Academic Search

    Carl J. Dister; Rich Schiferl

    1998-01-01

    Trending RMS current in an induction motor is often performed in industrial processes because of the availability and easy measurement of the parameter. This current can deviate widely with temperature, voltage and speed, making it difficult to determine process changes that are to be detected. Current deviations due to normal operation of the system can be corrected by applying the

  16. A modified Norde function for the measurement of the series resistance and the voltage-dependent barrier height of triangular barrier diodes

    Microsoft Academic Search

    G. S. Chilana; R. S. Gupta

    1989-01-01

    The Norde function [J. Appl. Phys. 50, 5052 (1979)] used for measuring the barrier height, series resistance, and ideality factor of a Schottky barrier diode has been modified to obtain the same parameters for a triangular barrier diode (TBD). Unlike Schottky barrier diodes, the barrier height of a TBD depends upon the applied voltage and changes linearly with it. In

  17. Application of modelling and computer simulation for the development of a test setup for calibration of power quality measurement transducers for high voltage networks

    Microsoft Academic Search

    HÉDIO TATIZAWA; ERASMO SILVEIRA NETO; GERALDO F. BURANI; ANTÔNIO A. C. A RRUDA; KLEIBER T. SOLETTO; NELSON M. MATSUO

    2008-01-01

    T he term power quality is, in general, closely related to the quality of the voltage. Considering the widespread presence of sensitive loads in the electric grid, and the increasing awareness of the consumers concerning the quality of the power supply, the control and measurement of power quality parameters, for instance, harmonics, interharmonics, sags, swells, etc., are increasingly becoming much

  18. Detection of oil-paper equilibrium moisture content in power transformers using hybrid intelligent interpretation of polarisation spectrums from recovery voltage measurements

    Microsoft Academic Search

    Syed M. Islam; P. R. S. Jota; M. Stace

    1998-01-01

    Detection of moisture in oil and paper is a key factor in determining the health of insulation in a power transformer. High moisture content severely degrades the insulating strength of oil and paper and may eventually cause failure. It is therefore highly desirable to detect incipient failure. Recently, a method based on Recovery Voltage Measurement (RVM) on transformers has been

  19. Detection of crevice corrosion under an O-ring by polarization resistance measurements using electrodes embedded in the O-ring

    SciTech Connect

    Inman, M.; Rawat, A.K.; Taylor, E.J. [Faraday Technology, Inc., Dayton, OH (United States); Moran, P.J. [Naval Academy, Annapolis, MD (United States). Mechanical Engineering Dept.

    1997-12-01

    An electrochemical sensor which incorporates a counter electrode (CE) and a reference electrode (RE) into an O-ring has been developed for in situ monitoring of crevice corrosion initiation and propagation. It is applicable to crevice corrosion situations where the crevice is created by a gasket or an O-ring and the attack occurs in that crevice. It is shown that polarization resistance (R{sub p}) values calculated from in situ electrochemical impedance measurements correlate with the onset of crevice attack and with its propagation for crevice corrosion of alloy 625 (UNS N06625) in 3.5% NaCl and in 10% FeCl{sub 3} solutions.

  20. Super-compliant metallic electrodes for electroactive polymer actuators

    NASA Astrophysics Data System (ADS)

    Habrard, Florian; Patscheider, Jörg; Kovacs, Gabor

    2012-04-01

    Electroactive polymer (EAP) actuators are compliant capacitors, where a thin elastomer film is sandwiched between two compliant electrodes. When a high DC voltage is applied to the electrodes, the arising electrostatic pressure squeezes the elastomer film in thickness and thus the film expands in planar directions. They are very promising candidates for "artificial muscles" development. Dielectric elastomer transducers benefit of important advantages compared to other electro-mechanical actuators: high energy density, large and noise-free deformation capability and low cost materials. However, if EAP devices have to be cheap, they work at high voltage (> 1000 V) leading to need for expensive electronics. Such operating conditions preclude their use close to the human body. The electrode material is also a challenge, since clean and fast processes suited to miniaturization of EAP devices are still missing. To solve these drawbacks, we are developing a new fabrication process aiming at reducing the dielectric layer thickness down to <20?m and to increase the efficiency using highly conductive electrode materials deposited by magnetron sputtering. In this work, we show how we succeed in finding the conditions for deposition of compliant metallic thin films that are able to maintain high conductivity at more than 10% stretching. The films are characterized by X-Ray Diffraction, electrical conductivity measurements and Atomic Force Microscopy.

  1. Changes in impedance of Ni electrodes upon standing and cycling

    NASA Technical Reports Server (NTRS)

    Reid, Margaret A.

    1989-01-01

    Impedances of Ni electrodes vary with many factors including voltage, cycling, and manufacturer. However, results from Ni/H2 cells being tested for Space Station Freedom show that consistent results are obtained within a group of cells from the same manufacturer if the cells are cycled and stored in the same manner. Impedance changes with storage and cycling are being investigated. Impedances are low in the fully charged state but rise abruptly by several orders of magnitude at a voltage corresponding to a very low state-of-charge. After standing for several months, this increase occurred at a higher voltage, consistent with an increase in structural order during storage which hinders diffusion of protons and reduces high rate capacity. Early measurements on the effects of cycling on Ni/H2 cells being tested for Space Station Freedom show differences between cells from different manufacturers.

  2. 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.

  3. Voltage Controlled Voltage Source (VCVS)

    NSDL National Science Digital Library

    Dorf, Richard C.

    Hosted by Clarkson University, this applet demonstrates a circuit that contains a voltage controlled voltage source (VCVS). The gain may be modified using the scroll bar. Even though brief, this resource can be used in a variety of different technical education classrooms.

  4. Development of an electrode cell impedance method to measure osteoblast cell activity in magnesium-conditioned media.

    PubMed

    Yun, YeoHeung; Dong, Zhongyun; Tan, Zongqing; Schulz, Mark J

    2010-04-01

    Magnesium (Mg) as a biodegradable metal has potential advantages as an implant material. This paper studies the effect of magnesium ions on osteoblast (U2-OS) behavior since magnesium implants mainly dissolve as divalent magnesium ions (Mg(2+)). A real-time monitoring technique based on electric cell-substrate impedance sensing (ECIS) was used for measuring cell proliferation, migration, adhesion, and cytotoxicity in magnesium-conditioned media. The impedance results show that U2-OS proliferation and adhesion were inhibited in not only a magnesium-free medium but also in a medium with a high concentration of magnesium. The impedance method produced more sensitive results than the output of an MTT assay. Other standard bioanalytical tests were conducted for comparison with the ECIS method. Immunochemistry was carried out to study cell adhesion in magnesium-conditioned media by staining using F-actin and alpha-tubulin and correlated cell density on the electrode with impedance. Bone tissue formation was studied using von Kossa staining and indicated the mineralization level of cells in magnesium-conditioned media decreased with the increase of magnesium ion concentration. Real-time PCR provided gene expression indicators of cell growth, apoptosis, inflammation, and migration. Compared to the bioanalytical methods of immunochemistry and MTT assays, which need preparation time and post-washing step, ECIS was able to measure cell activity in real time without any cell culture modification. In summary, ECIS might be an effective way to study biodegradable magnesium implants. PMID:20213174

  5. Through-the-electrode model of a proton exchange membrane fuel cell with independently measured parameters

    SciTech Connect

    Weisbrod, K.R.; Grot, S.A.; Vanderborgh, N.E.

    1995-05-01

    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 was investigated.

  6. 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.

  7. Work-Induced potassium changes in muscle venous effluent blood measured by ion-specific electrodes

    Microsoft Academic Search

    P. Hník; N. K?íž; F. Vysko?il; V. Smieško; J. Mejsnar; E. Ujec; M. Holas

    1973-01-01

    Modified Walker's liquid ion-exchanger microelectrodes were employed for measuring changes of K+ concentration in venous effluent blood from the cat gastrocnemius muscle during and after isometric tetani of various duration induced by indirect stimulation. The time course of these changes was obtained and the overall loss of K+ from a working muscle could thus be estimated. By comparing present results

  8. Time-resolved photoluminescence measurements for determining voltage-dependent charge-separation efficiencies of subcells in triple-junction solar cells

    NASA Astrophysics Data System (ADS)

    Tex, David M.; Ihara, Toshiyuki; Akiyama, Hidefumi; Imaizumi, Mitsuru; Kanemitsu, Yoshihiko

    2015-01-01

    Conventional external quantum-efficiency measurement of solar cells provides charge-collection efficiency for approximate short-circuit conditions. Because this differs from actual operating voltages, the optimization of high-quality tandem solar cells is especially complicated. Here, we propose a contactless method, which allows for the determination of the voltage dependence of charge-collection efficiency for each subcell independently. By investigating the power dependence of photoluminescence decays, charge-separation and recombination-loss time constants are obtained. The upper limit of the charge-collection efficiencies at the operating points is then obtained by applying the uniform field model. This technique may complement electrical characterization of the voltage dependence of charge collection, since subcells are directly accessible.

  9. Effect of a floating electrode on a plasma jet

    SciTech Connect

    Hu, J. T.; Wang, J. G.; Liu, X. Y.; Liu, D. W.; Lu, X. P. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China)] [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); Shi, J. J. [College of Science, Donghua University, Shanghai 201620 (China)] [College of Science, Donghua University, Shanghai 201620 (China); Ostrikov, K. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P. O. Box 218, Lindfield, New South Wales 2070 (Australia)] [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P. O. Box 218, Lindfield, New South Wales 2070 (Australia)

    2013-08-15

    Two kinds of floating electrode, floating dielectric barrier covered electrode (FDBCE) and floating pin electrode (FPE), which can enhance the performance of plasma jet are reported. The intense discharge between the floating electrode and power electrode decreased the voltage to trigger the plasma jet substantially. The transition of plasma bullet from ring shape to disk shape in the high helium concentration region happened when the floating electrode was totally inside the powered ring electrode. The enhanced electric field between propagating plasma bullet and ground electrode is the reason for this transition. The double plasma bullets happened when part of the FDBCE was outside the powered ring electrode, which is attributed to the structure and surface charge of FDBCE. As part of the FPE was outside the powered ring electrode, the return stroke resulted in a single intensified plasma channel between FPE and ground electrode.

  10. Impedance analysis of bio-fuel cell electrodes

    Microsoft Academic Search

    Sarinee Ouitrakul; Mana Sriyudthsak; Sumittra Charojrochkul; Toshihide Kakizono

    2007-01-01

    To determine the criteria for the selection of an electrode suitable for a bio-fuel cell (BFC), five electrodes, i.e. silver, aluminum, nickel, stainless steel and carbon fiber cloth were investigated. The performance of the BFC according to the electrode material, including the generated voltage, current density and power density was observed. These results show that the materials used for constructing

  11. Electric wind in electrode systems with corona points

    Microsoft Academic Search

    B. A. Kozlov; V. I. Solovyov

    2007-01-01

    The characteristics of the electric wind attendant on the corona initiation are studied with the aim of reaching a maximal\\u000a velocity and flow rate. Systems with a single corona point and multi-in-line electrode are used. The dependences of the gas\\u000a flow rate on the current, voltage, voltage polarity, electrode spacing, corona point geometry, and corona-free electrode design\\u000a are determined.

  12. 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.

  13. Multi Frequency Phase Fluorimetry (MFPF) for Oxygen Partial Pressure Measurement: Ex Vivo Validation by Polarographic Clark-Type Electrode

    PubMed Central

    Boehme, Stefan; Duenges, Bastian; Klein, Klaus U.; Hartwich, Volker; Mayr, Beate; Consiglio, Jolanda; Baumgardner, James E.; Markstaller, Klaus; Basciani, Reto; Vogt, Andreas

    2013-01-01

    Background Measurement of partial pressure of oxygen (PO2) at high temporal resolution remains a technological challenge. This study introduces a novel PO2 sensing technology based on Multi-Frequency Phase Fluorimetry (MFPF). The aim was to validate MFPF against polarographic Clark-type electrode (CTE) PO2 measurements. Methodology/Principal Findings MFPF technology was first investigated in N?=?8 anaesthetised pigs at FIO2 of 0.21, 0.4, 0.6, 0.8 and 1.0. At each FIO2 level, blood samples were withdrawn and PO2 was measured in vitro with MFPF using two FOXY-AL300 probes immediately followed by CTE measurement. Secondly, MFPF-PO2 readings were compared to CTE in an artificial circulatory setup (human packed red blood cells, haematocrit of 30%). The impacts of temperature (20, 30, 40°C) and blood flow (0.8, 1.6, 2.4, 3.2, 4.0 L min?1) on MFPF-PO2 measurements were assessed. MFPF response time in the gas- and blood-phase was determined. Porcine MFPF-PO2 ranged from 63 to 749 mmHg; the corresponding CTE samples from 43 to 712 mmHg. Linear regression: CTE?=?15.59+1.18*MFPF (R2?=?0.93; P<0.0001). Bland Altman analysis: meandiff 69.2 mmHg, rangediff -50.1/215.6 mmHg, 1.96-SD limits -56.3/194.8 mmHg. In artificial circulatory setup, MFPF-PO2 ranged from 20 to 567 mmHg and CTE samples from 11 to 575 mmHg. Linear regression: CTE?=??8.73+1.05*MFPF (R2?=?0.99; P<0.0001). Bland-Altman analysis: meandiff 6.6 mmHg, rangediff -9.7/20.5 mmHg, 1.96-SD limits -12.7/25.8 mmHg. Differences between MFPF and CTE-PO2 due to variations of temperature were less than 6 mmHg (range 0–140 mmHg) and less than 35 mmHg (range 140–750 mmHg); differences due to variations in blood flow were less than 15 mmHg (all P-values>0.05). MFPF response-time (monoexponential) was 1.48±0.26 s for the gas-phase and 1.51±0.20 s for the blood-phase. Conclusions/Significance MFPF-derived PO2 readings were reproducible and showed excellent correlation and good agreement with Clark-type electrode-based PO2 measurements. There was no relevant impact of temperature and blood flow upon MFPF-PO2 measurements. The response time of the MFPF FOXY-AL300 probe was adequate for real-time sensing in the blood phase. PMID:23565259

  14. High voltage solar array experiments

    NASA Technical Reports Server (NTRS)

    Kennerud, K. L.

    1974-01-01

    The interaction between the components of a high voltage solar array and a simulated space plasma is studied to obtain data for the design of a high voltage solar array capable of 15kW at 2 to 16kV. Testing was conducted in a vacuum chamber 1.5-m long by 1.5-m diameter having a plasma source which simulated the plasma conditions existing in earth orbit between 400 nautical miles and synchronous altitude. Test samples included solar array segments pinholes in insulation covering high voltage electrodes, and plain dielectric samples. Quantitative data are presented in the areas of plasma power losses, plasma and high voltage induced damage, and dielectric properties. Limitations of the investigation are described.

  15. Analysis of the reasons for accidents and of protective measures against induced voltage on aerial electrical transmission lines

    SciTech Connect

    Misrikhanov, M. Sh. [MES Tsentra (Russian Federation); Mirzaabdullaev, A. O. [Branch of JSC 'FSK EES'- Nizhegorodskoe PMES (Russian Federation)

    2009-01-15

    The problem of safety during work on aerial transmission lines under an induced voltage is examined. Results are presented from a study of the causes of accidents over the last 20 years in electrical grids in this country. A determination of different levels of induced voltage on disconnected aerial transmission lines as a function of their grounding scheme is proposed. The order of magnitudes for each level are given, along with approximate expressions for calculating them.

  16. Laboratory experiments on current flow between stationary and moving electrodes in magnetoplasmas

    NASA Technical Reports Server (NTRS)

    Stenzel, Reiner L.; Urrutia, J. M.

    1990-01-01

    Laboratory experiments were performed in order to investigate the basic physics of current flow between tethered electrodes in magnetoplasmas. The major findings are summarized. The experiments are performed in an effectively very large laboratory plasma in which not only the nonlinear current collection is addressed but also the propagation and spread of currents, the formation of current wings by moving electrodes, the current closure, and radiation from transmission lines. The laboratory plasma consists of a pulsed dc discharge whose Maxwellian afterglow provides a quiescent, current-free uniform background plasma. Electrodes consisting of collectors and electron emitters are inserted into the plasma and a pulsed voltage is applied between two floating electrodes via insulated transmission lines. Besides the applied current in the wire, the total current density in the plasma is obtained from space and time resolved magnetic probe measurements via Maxwell's law. Langmuir probes yield the plasma parameters.

  17. FIA-automated system used to electrochemically measure nitrite and its interfering chemicals through a 1-2 DAB / Au electrode: gain of sensitivity at upper potentials

    NASA Astrophysics Data System (ADS)

    Almeida, F. L.; dos Santos Filho, S. G.; Fontes, M. B. A.

    2013-03-01

    The measurement of nitrite and its interfering-chemicals (paracetamol, ascorbic acid and uric acid) was performed employing a Flow-injection Analysis (FIA) system, which was automated using solenoid valves and air-pump. It is very important to quantify nitrite from river water, food and biologic fluids due to its antibacterial capacity in moderated concentrations, or its toxicity for human health even at low concentrations (> 20 ?mol L-1 in blood fluids). Electrodes of the electrochemical planar sensor were defined by silk-screen technology. The measuring electrode was made from gold paste covered with 1-2 cis Diaminobenzene (DAB), which allowed good selectivity, linearity, repeatability, stability and optimized gain of sensitivity at 0.5 VAg/AgCl Nafion®117 (6.93 ?A mol-1 L mm-2) compared to 0.3 VAg/AgCl Nafion® 117. The reference electrode was obtained from silver/palladium paste modified with chloride and covered with Nafion® 117. The auxiliary electrode was made from platinum paste. It was noteworthy that nitrite response adds to the response of the studied interfering-chemicals and it is predominant for concentrations lower than 175 ?mol L-1.

  18. A flexible electrode array for muscle impedance measurements in the mouse hind limb: A tool to speed research in neuromuscular disease

    NASA Astrophysics Data System (ADS)

    Li, J.; Rutkove, S. B.

    2013-04-01

    Electrical impedance myography (EIM) is a bioelectrical impedance technique focused on the assessment of neuromuscular diseases using tetrapolar surface arrays. Recently, we have shown that reproducible and sensitive EIM measurements can be made on the gastrocnemius muscle of the mouse hind limb and that these are sensitive to disease alterations. A dedicated array would help speed data acquisition and provide additional sensitivity to disease-induced alterations. A flexible electrode array was developed with electrode sizes of 1mm × 1mm by Parlex, Inc. Tetrapolar electrode sets were arranged both parallel to (longitudinal) and orthogonally to (transverse) the major muscle fiber direction of the gastrocnemius muscle. Measurements were made with a dedicated EIM system. A total of 11 healthy animals and 7 animals with spinal muscular atrophy (a form of motor neuron disease) were evaluated after the fur was completely removed with a depilatory agent from the hind limb. Standard electrophysiologic testing (compound motor action potential amplitude and motor unit number estimation) was also performed. The flexible electrode array demonstrated high repeatability in both the longitudinal and transverse directions in the healthy and diseased animals (with intraclass correlation coefficients of 0.94 and 0.89, respectively, for phase angle measured transversely). In addition, differences between healthy and diseased animals were identifiable. For example, the 50 kHz transverse phase angle was higher in the healthy as compared to the SMA animals (16.8° ± 0.5 vs. 14.3° ± 0.7, respectively) at 21 weeks of age (p = 0.01). Differences in anisotropy were also identifiable. Correlations to several standard neurophysiologic parameters also appeared promising. This novel flexible tetrapolar electrode array can be used on the mouse hind limb and provides multidirectional data that can be used to assess muscle health. This technique has the potential of finding widespread use in the evaluation of drug therapies in neuromuscular animal disease models.

  19. Compact Electrochemical System Using On-Chip Sensor Electrodes and Integrated Devices

    NASA Astrophysics Data System (ADS)

    Yamazaki, Tomoyuki; Ikeda, Takaaki; Ishida, Makoto; Sawada, Kazuaki

    2011-04-01

    We report a compact electrochemical sensing system to implement cyclic voltammetry. This type of sensor needs a working electrode, counter electrode, and reference electrode, all of which were integrated on a single chip. The electrochemical system also needs a potentiostat and an input voltage-generating circuit, which were developed using on-chip active devices and a few discrete passive components. This is the first sensor system incorporating electrode-side input voltage generation for electrochemical measurements using an on-chip operational amplifier, which replaces a bulky external voltage controller. A continuous cyclic voltammetry measurement was conducted with a well-studied ferricyanide solution to demonstrate the operation of the intelligent sensor chip. A clear peak was observed and linearity to the target chemical concentration was obtained between the peak height and concentration of the ferricyanide solution. With potential for mass production and small size, this sensor chip could be the best candidate to realize point-of-care testing. This sensor chip is a milestone of a fully integrated electrochemical sensor chip.

  20. Characteristics of Skin-Electrode Impedance for a Novel Screw Electrode

    PubMed Central

    Jia, Wenyan; Wu, Jiamin; Gao, Di; Sun, Mingui

    2014-01-01

    Our group has developed a novel dry electrode, the skin screw electrode, for EEG measurement. This electrode can be conveniently and rapidly installed on the human scalp requiring no electrolyte application and skin preparation. In this paper, we further evaluate the performance of this electrode by investigating its frequency-dependent electrical impedance at the skin-electrode interface. Comparing with the traditional disc electrode, we found that the two types of electrodes showed very different spectral properties. We also found that the impedance of the screw electrode decreases after coating with gold. PMID:25642128

  1. Experimental and theoretical studies of the breakdown voltage characteristics at micrometre separations in air

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

    This paper presents experimental results and computer simulation for the direct current (DC) breakdown voltages in dry, synthetic and ambient air and discharge gaps ranging from 1 to 100 ?m. The measured breakdown voltage curves were systematically analyzed and the effective electron yields from cathode for dry and synthetic air as a function of the reduced electric field have been estimated. As complement to the experimental results, simulations have been performed using a kinetic particle-in-cell (PIC) code. For the electrode gaps less than 20 ?m, both experimental and simulation results revealed an interesting departures from the Paschen law on the left-hand side of the Paschen curve. The present results should be useful for the determination of minimum ignition voltages in microplasma sources as well as the maximum safe operating voltages and critical dimensions in other microdevices, high-power switches and circuit breakers.

  2. Electrode measurements of the oxidation-reduction potential in the Gotland Deep using medium-term moored profiling instrumentation

    NASA Astrophysics Data System (ADS)

    Meyer, David; Prien, Ralf; Dellwig, Olaf; Schulz-Bull, Detlef

    2013-04-01

    The variation of in situ redox potential (Eh) was studied in the stratified water column (30 - 185 m) of the central Baltic Sea, for a period of 56 days (November, 2010 - January, 2011) using the Gotland Deep Environmental Sampling Station (GODESS) in order to identify the processes that control Eh. During the deployment of the mooring 170 profiles of hydro-physical parameters were registered, including the oxidation-reduction potential, pH, dissolved oxygen, chlorophyll a fluorescence, turbidity, temperature and conductivity. In general, the measured Eh (with respect to standard hydrogen electrode, SHE) ranged from - 55 to 167 mV. A comparison of the measured Eh with that calculated for the particular redox couples was carried out by applying the Nernst-equation. The standard reduction potentials were corrected for temperature and pH. Furthermore, the concentrations of the most important redox components such as Fe, Mn, N, O, C and S used for comparison were estimated by using empirical functions or were based on measurements of discrete water samples, taken at the time of deployment and recovery of the mooring. The results reveal that the reduction of Fe(III) essentially controls the electrode potential of the redox sensor in most parts of the anoxic waters. Below the redoxcline the reduction of hematite and then ferric oxyhydroxid could be related to the redox potential and somewhat deeper Fe(III)/Fe(II) was found to be the dominant redox couple. Theoretically a mixed potential theory should have been applied because in natural waters a variety of redox pairs is present but Fe couples appear to dominate all the other redox equlibria. This could be explained by the relatively high exchange current of Fe and by the high concentrations (up to 1.5 µM) present at those depths in the study area. However, there are still gaps in our knowledge about the cycling of redox-sensitive elements and long-term moored profiling instrumentations may help to improve our understanding. Thus, we are pursuing the use of in situ analyzers for electro active compounds on moored systems in the future. In this case, analyzer data would be associated with chemical and physical parameters measured with high resolution in time and space, giving information on mixing processes and reaction kinetics. This approach is required to assess the relevance, for instance, of intrusions of oxygenated waters, vertical eddy-diffusion and fluctuations caused by internal waves on the cycle of redox-sensitive elements. This is particularly important as lateral transport appears to play a dominant role along isopycnal surfaces, especially in medium-sized stratified basins and yet have not been investigated extensively in the Baltic Sea with respect to the cycles of the most electro-active compounds.

  3. Built-in voltage of organic bulk heterojuction p-i-n solar cells measured by electroabsorption spectroscopy

    SciTech Connect

    Siebert-Henze, E., E-mail: ellen.siebert@iapp.de; Lyssenko, V. G.; Fischer, J.; Tietze, M.; Brueckner, R.; Schwarze, M.; Vandewal, K.; Ray, D.; Riede, M.; Leo, K. [Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden (Germany)] [Institut für Angewandte Photophysik, Technische Universität Dresden, D-01062 Dresden (Germany)

    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.

  4. 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.

  5. 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.

  6. Nonlinear antiferroelectric-like capacitance-voltage curves in ferroelectric BiFeO3 thin films

    NASA Astrophysics Data System (ADS)

    Jiang, A. Q.; Zhang, D. W.; Tang, T. A.

    2013-07-01

    The ferroelectric capacitance is usually nonlinear against increasing/decreasing voltage in sweeping time longer than 1 s and achieves a maximum value at around a coercive voltage within each loop. With the improved short-pulse measurements, we estimated the differential capacitance of ferroelectric Au/BiFeO3/LaNiO3/SrTiO3 thin-film capacitors from a nanosecond discharging current induced by a delta voltage after a stressing voltage pulse with widths of 500 ns-50 ms. With the shortening of the voltage sweeping time, we clearly observed two capacitance maxima from each branch of a capacitance-voltage (C-V) loop, reminiscent of an antiferroelectric behavior. After transformation of nanosecond domain switching current transients under pulses into polarization-voltage hysteresis loops, we further measured time dependent polarization retention as well as imprint in the range of 100 ns-1 s. Both positive and negative polarizations decay exponentially at characteristic times of 2.25 and 198 ?s, suggesting the coexistence of preferred domains pointing to top and bottom electrodes in most epitaxial films. This exponential time dependence is similar to the dielectric degradation under a dc voltage, and the polarization retention can be improved through long-time opposite voltage stressing. With this improvement, the additional antiferroelectric-like dielectric maximum within each branch of a C-V loop disappears. This experiment provides the strong evidence of the effect of time-dependent charge injection on polarization retention and dielectric degradation.

  7. Electrode contamination effects of retarding potential analyzer.

    PubMed

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

    2014-01-01

    The electrode contamination in electrostatic analyzers such as Langmuir probes and retarding potential analyzers (RPA) is a serious problem for space measurements. The contamination layer acts as extra capacitance and resistance and leads to distortion in the measured I-V curve, which leads to erroneous measurement results. There are two main effects of the contamination layer: one is the impedance effect and the other is the charge attachment and accumulation due to the capacitance. The impedance effect can be reduced or eliminated by choosing the proper sweeping frequency. However, for RPA the charge accumulation effect becomes serious because the capacitance of the contamination layer is much larger than that of the Langmuir probe of similar dimension. The charge accumulation on the retarding potential grid causes the effective potential, that ions experience, to be changed from the applied voltage. Then, the number of ions that can pass through the retarding potential grid to reach the collector and, thus, the measured ion current are changed. This effect causes the measured ion drift velocity and ion temperature to be changed from the actual values. The error caused by the RPA electrode contamination is expected to be significant for sounding rocket measurements with low rocket velocity (1-2 km/s) and low ion temperature of 200-300 K in the height range of 100-300 km. In this paper we discuss the effects associated with the RPA contaminated electrodes based on theoretical analysis and experiments performed in a space plasma operation chamber. Finally, the development of a contamination-free RPA for sounding rocket missions is presented. PMID:24517809

  8. Sodium Flux in Necturus Proximal Tubule under Voltage Clamp

    PubMed Central

    Spring, Kenneth R.; Paganelli, Charles V.

    1972-01-01

    Na transport and electrical properties of Necturus renal proximal tubules were analyzed, in vivo, by a voltage clamp method which utilizes an axial electrode in the tubule lumen for passage of current and simultaneous determination of net fluid (or Na) flux by the split droplet method. When the average spontaneous transepithelial potential difference of –8 mv (lumen negative) was reduced to zero by current passage, net Na flux doubled from a mean of 107 to 227 pmoles/cm2 per sec. The relationship between flux and potential over the range –25 to +10 mv was nonlinear, with flux equilibrium at –15 mv and droplet expansion at more negative values. Calculated Na permeability at flux equilibrium was 7.0 x 10–6 cm/sec. Voltage transients, similar to those caused by intraepithelial unstirred layers, were observed at the end of clamping periods. Tubular electrical resistance measured by brief square or triangle wave pulses (<100 msec) averaged 43 ohm cm2. The epithelial current-voltage relationship was linear over the range –100 to +100 mv, but displayed marked hysteresis during low frequency (<0.04 Hz) triangle wave clamps. The low transepithelial resistance and large opposing unidirectional ion fluxes suggest that passive ionic movements occur across extracellular shunt pathways, while the voltage transients and current-voltage hysteresis are consistent with the development of a local osmotic gradient within epithelium. PMID:5049078

  9. Design, fabrication and evaluation of a conforming circumpolar peripheral nerve cuff electrode for acute experimental use

    PubMed Central

    Foldes, Emily L.; Ackermann, D. Michael; Bhadra, Niloy; Kilgore, Kevin L.; Bhadra, Narendra

    2011-01-01

    Nerve cuff electrodes are a principle tool of basic and applied electro-neurophysiology studies and are championed for their ability to achieve good nerve recruitment with low thresholds. We describe the design and method of fabrication for a novel circumpolar peripheral nerve electrode for acute experimental use. This cylindrical cuff-style electrode provides approximately 270 degrees of radial electrode contact with a nerve for each of an arbitrary number of contacts, has a profile that allows for simple placement and removal in an acute nerve preparation, and is designed for adjustment of the cylindrical diameter to ensure a close fit on the nerve. For each electrode, the electrical contacts were cut from 25 µm platinum foil as an array so as to maintain their positions relative to each other within the cuff. Lead wires were welded to each intended contact. The structure was then molded in silicone elastomer, after which the individual contacts were electrically isolated. The final electrode was curved into a cylindrical shape with an inner diameter corresponding to that of the intended target nerve. The positions of these contacts were well maintained during the molding and shaping process and failure rates during fabrication due to contact displacements were very low. Established electrochemical measurements were made on one electrode to confirm expected behavior for a platinum electrode and to measure the electrode impedance to applied voltages at different frequencies. These electrodes have been successfully used for nerve stimulation, recording, and conduction block in a number of different acute animal experiments by several investigators. PMID:21187115

  10. Epitaxial graphene contact electrode for silicon carbide based ultraviolet photodetector

    NASA Astrophysics Data System (ADS)

    Kus¸demir, Erdi; Özkendir, Dilce; F?rat, Volkan; Çelebi, Cem

    2015-03-01

    We present the fabrication and characterization of graphene-semiconductor-graphene ultraviolet photodetector based on the rectifying character of Schottky junction at the interface between epitaxial graphene and SiC semiconductor. As-grown single layer epitaxial graphene is interdigitated as transparent conductive electrode to probe photo-generated charge carriers in a semi-insulating 4H-SiC substrate. The fabricated device exhibits the typical current-voltage characteristics of a conventional metal-semiconductor-metal type photodetector with low leakage current. Time-resolved photocurrent measurements suggest an excellent photocurrent reversibility and high response speed of the device. The measurements performed for different illumination wavelengths showed that the sample reveals higher responsivity values when it is exposed to the light with 254?nm wavelength. The obtained results imply that epitaxial graphene can be used readily as transparent conductive electrode for SiC based optoelectronic device applications.

  11. Experimental Proof of Voltage-Current Waveform Sensor Output of Resin Molded Type for Measurement of Power Factor and Harmonics in General Power Distribution System

    NASA Astrophysics Data System (ADS)

    Furukawa, Tatsuya; Hirakawa, Masahito; Fukumoto, Hisao; Yoshino, Shinya; Ohchi, Masashi

    We have proposed the voltage-current sensor of resin molded type for measurement of the power factor and harmonics. To grasp the characteristics of the conventional prototype sensor and the problem in its practical use, we have conducted the finite element analysis for that. There occurred problems on the cost and the practical usage in making use of the sensor consequently. Therefore we have redesigned the prototype sensor, where the current sensor designed based on the FEM and a ready-made voltage sensor have been incorporated. In this paper, we will describe the feasibility field experiment of the present sensor in the practical 6.6kV distribution system and show that the sensor can measure the power factor and harmonics for the horizontal and vertical power line systems successfully.

  12. 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.

  13. Subdural Electrodes

    PubMed Central

    Lesser, Ronald P.; Crone, Nathan E.; Webber, W.R.S.

    2010-01-01

    Subdural electrodes are frequently used to aid in the neurophysiological assessment of patients with intractable seizures. We review the indications for these, their uses for localizing epileptogenic regions and for localizing cortical regions supporting movement, sensation, and language. PMID:20573543

  14. 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.

  15. 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.

  16. Photoacoustic measurements for catalytic effects of perovskite electrodes in a sealed-off CO2 discharge tube

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Ho; Choi, Joong-Gill; Cho, Ung-In

    1998-09-01

    To investigate catalytic activities of perovskite-type electrodes in a sealed-off CO2 laser cavity, we studied the dissociation and reformation reactions of CO2 during electric discharge by monitoring the concentration change of CO2 as a function of time. A photoacoustic spectroscopy detection was introduced to measure the amount of CO2 in a closed discharge system. The catalytic activities in the dissociation of CO2 were demonstrated and compared for both Cu and La0.7Sr0.3CoO3 cathodes. The discharge with the gas mixture of CO2:N2:He=1:1:8 was performed under nine combinations of different conditions at pressures of 10, 20, and 30 Torr and discharge currents of 3, 4, and 5 mA. Within 1 min after the discharge, the concentration of CO2 reduced drastically by as much as 60% for both cathodes. In the case of the Cu cathode, the amounts of CO2 in the tube had not recovered even after 30 min, while with the perovskite cathode the CO2 contents recovered slowly up to 90%-95% within 5 min and then remained almost unchanged. The dissociation of CO2 with the Cu cathode increased as the total pressure decreased and the discharge current increased. The La0.7Sr0.3CoO3 cathode, however, demonstrated strong suppression in the dissociation of CO2 according to the reformation reaction of CO+(1/2)O2?CO2 by its catalytic activity.

  17. 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.

  18. Internal voltages in GaInP /GaInAs/Ge multijunction solar cells determined by electroluminescence measurements

    NASA Astrophysics Data System (ADS)

    Kirchartz, Thomas; Rau, Uwe; Hermle, Martin; Bett, Andreas W.; Helbig, Anke; Werner, Jürgen H.

    2008-03-01

    We analyze electroluminescence spectra of a GaInP /GaInAs/Ge triple-junction solar cell at different injection currents. Using the reciprocity theorem between electroluminescent emission and external quantum efficiency of solar cells allows us to derive the current/voltage curves and the diode quality factors of all individual subcells.

  19. Simple voltage tunable liquid crystal laser

    NASA Astrophysics Data System (ADS)

    Blinov, L. M.; Cipparrone, G.; Mazzulla, A.; Pagliusi, P.; Lazarev, V. V.; Palto, S. P.

    2007-03-01

    Lasing has been observed in a dye-doped liquid crystal placed between one substrate with a large transparent electrode and the other with a system of parallel nontransparent electrode stripes of 15?m period. The stripes operate as a shadow mask providing the spatial modulation of the pump beam and material gain and, with the voltage applied, it additionally creates a Bragg resonator structure due to the spatial modulation of refraction. With that simple cell, a voltage induced tuning of the spectral positions of laser lines over 25nm has been demonstrated.

  20. Test, Construction, and Calibration of a Fast Valve Driver Unit (FVDU) and an Earth-isolated High Voltage Probe (HV probe) for a pulsed plasma experiment

    NASA Astrophysics Data System (ADS)

    Kamikawa, Yu; von der Linden, Jens; You, Setthivoine

    2013-10-01

    A fast valve driver unit (FVDU) and an optically isolated high voltage probe (HV probe) were built for an experiment to generate laboratory astrophysical jets with a triple electrode plasma gun. The FVDU controls fast pulse gas valves (Parker P/N: 9S4-A1-P2-9B13, 090-0270-090) by converting an optical trigger input into a square 6 V pulse output of a desired duration (100 ?s to 1ms) with an initial 250 V shot pulse. A potentiometer controls the duration of the square pulse, corresponding to the open time of the valve. The solar cell powered HV probe measures, once triggered by an optical pulse, the voltage across the electrodes without exposing sensitive data acquisition instruments to high voltage. A custom made capacitive voltage divider couples the signal to a solar powered LED, which optically transmit the signal to a receiver circuit. The voltage across the electrodes controls the current driven across the jet and the azimuthal rotation of the jet. A fast valve driver unit (FVDU) and an optically isolated high voltage probe (HV probe) were built for an experiment to generate laboratory astrophysical jets with a triple electrode plasma gun. The FVDU controls fast pulse gas valves (Parker P/N: 9S4-A1-P2-9B13, 090-0270-090) by converting an optical trigger input into a square 6 V pulse output of a desired duration (100 ?s to 1ms) with an initial 250 V shot pulse. A potentiometer controls the duration of the square pulse, corresponding to the open time of the valve. The solar cell powered HV probe measures, once triggered by an optical pulse, the voltage across the electrodes without exposing sensitive data acquisition instruments to high voltage. A custom made capacitive voltage divider couples the signal to a solar powered LED, which optically transmit the signal to a receiver circuit. The voltage across the electrodes controls the current driven across the jet and the azimuthal rotation of the jet. This work was sponsored in part by the US DOE Grant DE-SC0010340.

  1. Enhanced performance of sulfone-based electrolytes at lithium ion battery electrodes, including the LiNi0.5Mn1.5O4 high voltage cathode

    E-print Network

    Angell, C. Austen

    in the performance (safety, energy density, and power) of the standard lithium ion batteries e which approachEnhanced performance of sulfone-based electrolytes at lithium ion battery electrodes, including 2014 Available online 27 March 2014 Keywords: Lithium ion battery Sulfone-based electrolytes High

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Charge Lifetime Measurements at High Average Current Using a K{sub 2}CsSb Photocathode inside a DC High Voltage Photogun

    SciTech Connect

    Mammei, Russell; Feingold, Joshua; Adderley, Philip; Clark, James; Covert, Steven; Grames, Joseph; Hansknecht, John; Machie, Danny; Poelker, Benard; Rao, Triveni; Smedley, John; Walsh, John; McCarter, James

    2013-03-01

    Two K{sub 2}CsSb photocathodes were manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure ~ 10{sup -11} Torr. These photocathodes were evaluated using a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at wavelengths 440 or 532 nm, to generate dc electron beams at currents up to 20 mA. Some conditions produced exceptionally large photocathode charge lifetimes, without measurable quantum efficiency (QE) decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. Under other conditions the charge lifetime was poor, suggesting a complex QE decay mechanism likely related to chemistry and localized heating via the laser beam. Following beam delivery, the photocathodes were evaluated using a scanning electron microscope with energy dispersive x-ray spectroscopy capability, to determine surface morphology and chemical composition.

  7. Measurement of sodium ion concentration in undiluted urine with cation-selective polymeric membrane electrodes after the removal of interfering compounds

    PubMed Central

    Phillips, Feyisayo; Kaczor, Kim; Gandhi, Neel; Pendley, Bradford D.; Danish, Robert K.; Neuman, Michael R.; Toth, Blanka; Horvath, Viola; Lindner, Erno

    2007-01-01

    The measurement of sodium ion concentration in urine can provide diagnostic information and guide therapy. Unfortunately, neutral-carrier-based ion-selective electrodes show a large positive drift and loss in selectivity in undiluted urine. The extraction of electrically neutral lipids from the urine into the sensing membrane was suggested as the main source of the drift, loss of selectivity and the consequent incorrect concentration readings. In this work, (i) solvent-solvent extraction, (ii) membrane-immobilized solvent extraction, and (iii) solid phase extraction were used to remove interfering compounds from urine samples. The “cleaned” urine samples were subsequently analyzed using a calixarene (sodium ionophore X)-based, solid-contact, sodium-selective electrode in a flow-through manifold. The solid-contact sodium sensors had excellent stability in cleaned urine and an acceptable bias compared to commercial clinical analyzers. PMID:18371638

  8. The influence of a voltage ramp on the measurement of I-V characteristics of a solar cell

    NASA Technical Reports Server (NTRS)

    Von Roos, O.

    1980-01-01

    For efficiency and convenience the voltage applied to a Si solar cell is often fairly rapidly driven from zero to the open circuit value typically at a common rate of 1 V per millisecond. During this time the values of current are determined as a function of the instantaneous voltage thus producing an I-V characteristic. The present paper shows that the customary expressions for the current as a function of cell parameters still remain valid provided that the diffusion length in the expression for the dark current is changed from its steady state value L to the effective diffusion length L1 given by L1 = L(1 + qV/kT.tau) to the -1/2, where V is the ramp rate considered constant and tau is the lifetime of minority carriers. This result is true to a very good approximation provided that low level injection prevails.

  9. High-voltage interactions in plasma wakes: Simulation and flight measurements from the Charge Hazards and Wake Studies (CHAWS) experiment

    Microsoft Academic Search

    V. A. Davis; M. J. Mandell; D. L. Cooke; C. L. Enloe

    1999-01-01

    The Charge Hazards and Wake Studies (CHAWS) flight experiment flew on the Wake Shield Facility (WSF) aboard STS-60 and STS-69. The experiment studied high-voltage current collection within the spacecraft wake. The wake-side sensor was a 45-cm-long, biasable cylindrical probe mounted on the 3.66-m-diameter WSF. Operations were performed in free flight and at various attitudes while on the shuttle orbiter remote

  10. The distribution of barrier heights in MIS type Schottky diodes from current–voltage–temperature ( I– V– T) measurements

    Microsoft Academic Search

    Adem Tataro?lu; ?emsettin Alt?ndal

    2009-01-01

    The forward bias current–voltage–temperature (I–V–T) characteristics of the Au\\/SiO2\\/n-Si (MIS) type Schottky diodes (SDs) have been investigated in the temperature range of 300–400K. The estimated zero-bias barrier height (?B0) and the ideality factor (n) assuming thermionic emission (TE) theory show strong temperature dependence. An abnormal decrease in the ?B0 and an increase in the n with decreasing temperature have been

  11. Analysis of capacitance-voltage measurements on heat-treated Cu2-xS\\/CdS heterojunctions

    Microsoft Academic Search

    R. B. Hall; V. P. Singh

    1979-01-01

    The capacitance-voltage characteristics of a p-type (metalllike)\\/n-type semiconductor junction are described in terms of a simple three-region space charge in the semiconductor. The assumed space charge consists of a narrow (~100 A˚) high-density space charge at the interface, followed by an extended low-density space charge (insulating layer), and finally the bulk space charge. The calculations assume that the equilibrium space-charge

  12. Analysis of capacitance-voltage measurements on heat-treated Cu2?xS\\/CdS heterojunctions

    Microsoft Academic Search

    R. B. Hall; V. P. Singh

    1979-01-01

    The capacitance-voltage characteristics of a p-type (metalllike)\\/n-type semiconductor junction are described in terms of a simple three-region space charge in the semiconductor. The assumed space charge consists of a narrow (?100 A?) high-density space charge at the interface, followed by an extended low-density space charge (insulating layer), and finally the bulk space charge. The calculations assume that the equilibrium space-charge

  13. Development of a method of measuring relative phase difference between sending and receiving voltage on a power line

    E-print Network

    Rackley, Benton Tiburce

    1950-01-01

    of Measuri np, Relative Phase Difference Between Sending ~nd Receiving Voltage on ~ Power Line. Conclusions. 4. Bibliography 29 FIGURFS 1. Two Machine System 2. Magnetic Cylinder Shunt for Current Transformer 4. Phase Shift Meter Network 5. Standard... of Phase Angle vs. Load Reading . . . . . 26 INTNODUGTION During World War II the electrical power system of the United States was operated at full cap~city--indeed, m~ny units carr1ed overloads for extended periods of time. genera tins stations...

  14. Measurement of minority carrier lifetime in solar cells from photo-induced open-circuit voltage decay

    Microsoft Academic Search

    JOHN E. MAHAN; THOMAS W. EKSTEDT; ROBERT I. FRANK; R. Kaplow

    1979-01-01

    We present an experimental technique for determining the excess minority carrier lifetime within the base region of p-n junction solar cells. The procedure is to forward-bias the solar cell with a flash from a stroboscope and then to monitor the decay of the open-circuit voltage. Results are given for conventional horizontal-junction devices, as well as for vertical single- and multijunction

  15. Measurement of minority carrier lifetime in solar cells from photo-induced open-circuit voltage decay

    Microsoft Academic Search

    J. E. Mahan; T. W. Ekstedt; R. I. Frank; R. Kaplow

    1979-01-01

    An experimental technique is presented for determining the excess minority carrier lifetime within the base region of p-n junction solar cells. The procedure is to forward-bias the solar cell with a flash from a stroboscope and then to monitor the decay of the open-circuit voltage. Results are given for conventional horizontal-junction devices, as well as for vertical single- and multijunction

  16. 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.

  17. 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.

  18. I-V Characteristic for ZnO MSM Photodetector with Pd Contact Electrodes on PPC Plastic

    SciTech Connect

    Jandow, N. N.; Ibrahim, K.; Hassan, H. Abu [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia 11800 Minden, Penang (Malaysia)

    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.

  19. Investigation of stability for an electrostatically actuated flexible electrode

    NASA Astrophysics Data System (ADS)

    Hinton, Cory; McFarland, Matthew; Ward, Thomas

    2012-02-01

    An argument for employing dimensional analysis to explore stability in an electrostatically actuated flexible electrode is presented theoretically and experimentally. The electrode is configured as a cantilever beam, as many applications in MEMs, medical devices, and sensing devices have been studied for years. This study investigates a macro scale beam (length = 100mm - 150mm), for applications in cooling fan and flapping micro air vehicle devices. The influence of scale is validated, voltage potential and frequency contributions are quantitatively measured, and a comparison of input signal (analog versus digital) is discussed using dynamical systems analysis. Based on experimental data and numerical models, characteristics of stability are presented that could influence design considerations for various micro- and macro-scale devices.

  20. Biomedical Implementation of Liquid Metal Ink as Drawable ECG Electrode and Skin Circuit

    PubMed Central

    Yu, Yang; Zhang, Jie; Liu, Jing

    2013-01-01

    Background Conventional ways of making bio-electrodes are generally complicated, expensive and unconformable. Here we describe for the first time the method of applying Ga-based liquid metal ink as drawable electrocardiogram (ECG) electrodes. Such material owns unique merits in both liquid phase conformability and high electrical conductivity, which provides flexible ways for making electrical circuits on skin surface and a prospective substitution of conventional rigid printed circuit boards (PCBs). Methods Fundamental measurements of impedance and polarization voltage of the liquid metal ink were carried out to evaluate its basic electrical properties. Conceptual experiments were performed to draw the alloy as bio-electrodes to acquire ECG signals from both rabbit and human via a wireless module developed on the mobile phone. Further, a typical electrical circuit was drawn in the palm with the ink to demonstrate its potential of implementing more sophisticated skin circuits. Results With an oxide concentration of 0.34%, the resistivity of the liquid metal ink was measured as 44.1 µ?·cm with quite low reactance in the form of straight line. Its peak polarization voltage with the physiological saline was detected as ?0.73 V. The quality of ECG wave detected from the liquid metal electrodes was found as good as that of conventional electrodes, from both rabbit and human experiments. In addition, the circuit drawn with the liquid metal ink in the palm also runs efficiently. When the loop was switched on, all the light emitting diodes (LEDs) were lit and emitted colorful lights. Conclusions The liquid metal ink promises unique printable electrical properties as both bio-electrodes and electrical wires. The implemented ECG measurement on biological surface and the successfully run skin circuit demonstrated the conformability and attachment of the liquid metal. The present method is expected to innovate future physiological measurement and biological circuit manufacturing technique in a large extent. PMID:23472220

  1. Impedance characteristics of deep brain stimulation electrodes in vitro and in vivo

    NASA Astrophysics Data System (ADS)

    Wei, Xuefeng F.; Grill, Warren M.

    2009-08-01

    The objective of this study was to quantify the electrode-tissue interface impedance of electrodes used for deep brain stimulation (DBS). We measured the impedance of DBS electrodes using electrochemical impedance spectroscopy in vitro in a carbonate- and phosphate-buffered saline solution and in vivo following acute implantation in the brain. The components of the impedance, including the series resistance (Rs), the Faradaic resistance (Rf) and the double layer capacitance (Cdl), were estimated using an equivalent electrical circuit. Both Rf and Cdl decreased as the sinusoidal frequency was increased, but the ratio of the capacitive charge transfer to the Faradaic charge transfer was relatively insensitive to the change of frequency. Rf decreased and Cdl increased as the current density was increased, and above a critical current density the interface impedance became nonlinear. Thus, the magnitude of the interface impedance was strongly dependent on the intensity (pulse amplitude and duration) of stimulation. The temporal dependence and spatial non-uniformity of Rf and Cdl suggested that a distributed network, with each element of the network having dynamics tailored to a specific stimulus waveform, is required to describe adequately the impedance of the DBS electrode-tissue interface. Voltage transients to biphasic square current pulses were measured and suggested that the electrode-tissue interface did not operate in a linear range at clinically relevant current amplitudes, and that the assumption of the DBS electrode being ideally polarizable was not valid under clinical stimulating conditions.

  2. Seismic mass Top electrode

    E-print Network

    Kraft, Michael

    of which provides loop transducer is described. A bulk-micromachined an accurate measure is that the micromachined, capacitive sensing element had only three connections (top and bottom electrodes and seismic mass domains, (Burstein and Kaiser, 1996). Usually, for an analogue, closed loop accelerometer the latter

  3. 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.

  4. Generation of Atmospheric Pressure Plasma by Repetitive Nanosecond Pulses in Air Using Water Electrodes

    NASA Astrophysics Data System (ADS)

    Shao, Tao; Yu, Yang; Zhang, Cheng; Jiang, Hui; Yan, Ping; Zhou, Yuanxiang

    2011-12-01

    Dielectric barrier discharge (DBD) excitated by pulsed power is a promising method for producing nonthermal plasma at atmospheric pressure. Discharge characteristic in a DBD with salt water as electrodes by a home-made unipolar nanosecond-pulse power source is presented in this paper. The generator is capable of providing repetitive pulses with the voltage up to 30 kV and duration of 70 ns at a 300 ? resistive load. Applied voltage and discharge current are measured under various experimental conditions. The DBD created between two liquid electrodes shows that the discharge is homogeneous and diffuse in the whole discharge regime. Spectra diagnosis is conducted by an optical emission spectroscopy. The air plasma has strong emission from nitrogen species below 400 nm, notably the nitrogen second positive system.

  5. 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.

  6. 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.

  7. 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.

  8. Functionalized nano interdigitated electrodes arrays on polymer with integrated microfluidics for direct bio-affinity sensing using impedimetric measurement

    Microsoft Academic Search

    Zhiwei Zou; Junhai Kai; Michael J. Rust; Jungyoup Han; Chong H. Ahn

    2007-01-01

    This paper presents a fully integrated nano interdigitated electrodes array (nIDA) and microfluidic system on polymer substrate. It can be used as a miniaturized, sensitive, and easy-to-use impedimetric sensor for genomics, proteomics, and cellular analysis. The benefits gained from a nanoscale IDA is very high sensitivity for monitoring protein binding behavior. With the intention of integrating this nano biosensor into

  9. Flow injection measurement of lead using mercury-free disposable gold-sputtered screen-printed carbon electrodes (SPCE)

    Microsoft Academic Search

    P. Masawat; S. Liawruangrath; J. M. Slater

    2003-01-01

    Screen-printed sensors are promising devices for disposable, cheap and reliable environmental monitoring. In previous studies, workers have used mercury-coated electrodes to allow stripping voltammetry to be performed. In this paper, we describe a disposable sputtered gold sensor which allows underpotential analyte preconcentration and avoids the environmental contamination associated with mercury-based sensors. It is used in combination with a specially fabricated

  10. Current-voltage-temperature characteristics of DNA origami.

    PubMed

    Bellido, Edson P; Bobadilla, Alfredo D; Rangel, Norma L; Zhong, Hong; Norton, Michael L; Sinitskii, Alexander; Seminario, Jorge M

    2009-04-29

    The temperature dependences of the current-voltage characteristics of a sample of triangular DNA origami deposited in a 100 nm gap between platinum electrodes are measured using a probe station. Below 240 K, the sample shows high impedance, similar to that of the substrate. Near room temperature the current shows exponential behavior with respect to the inverse of temperature. Sweep times of 1 s do not yield a steady state; however sweep times of 450 s for the bias voltage secure a steady state. The thermionic emission and hopping conduction models yield similar barriers of approximately 0.7 eV at low voltages. For high voltages, the hopping conduction mechanism yields a barrier of 0.9 eV and the thermionic emission yields 1.1 eV. The experimental data set suggests that the dominant conduction mechanism is hopping in the range 280-320 K. The results are consistent with theoretical and experimental estimates of the barrier for related molecules. PMID:19420582

  11. 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.

  12. An experimental measurement of corona discharge using laser Doppler velocimetry

    Microsoft Academic Search

    C. A. Belhadj; M. H. Shwehdi; A. S. Farag; F. M. Zedan; U. K. A. Klein

    1998-01-01

    A point to plane testing discharge system was constructed allowing the flow of air to pass, circulate and return to its initial status, when corona is initiated by the alternating applied voltage on the stressed electrode. The corona wind velocity was measured by means of a laser Doppler velocimetry system implemented and calibrated in the laboratory. The velocity measurement was

  13. Breakdown and Partial Discharge Measurements of Some Commonly Used Dielectric Materials in Liquid Nitrogen for HTS Applications

    SciTech Connect

    James, David Randy [ORNL; Sauers, Isidor [ORNL; Ellis, Alvin R [ORNL; Tuncer, Enis [ORNL; Tekletsadik, Kasegn [Consultant, SuperPower, Inc.; Hazelton, Drew [SuperPower Incorporated, Schenectady, New York

    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.

  14. A commercial MOSFET-based biosensor with a gold extended gate electrode

    NASA Astrophysics Data System (ADS)

    Lyu, Hong-Kun; Choi, Young-Sam; Shin, Jang-Kyoo; Kim, Jae-Hyun

    2009-05-01

    This paper presents a commercial metal-oxide-semiconductor field-effect transistor (MOSFET)-based biosensor with a gold extended-gate electrode for the electronic detection of C-reactive protein (CRP). From a component point of view, the commercial MOSFET-based biosensor consists of a commercial MOSFET with a socket for connecting the gold electrode which was fixed on a printed circuit board (PCB) and a reaction-vessel module which was assembled with the gold electrode and the Ag/AgCl reference electrode. The gold electrode with only one gold layer was fabricated on a glass substrate simply and it was used as the extended-gate metal to form a self-assembled monolayer (SAM). The binding of the CRP to anti-CRP was detected by measuring the electrical characteristics of the biosensor. Variation of the drain current before and after the interaction of CRP and anti-CRP was about 1.2mA on the measured IDS-VDS and real-time characteristics. The concentration of the CRP solution was adjusted to 10?g/ml by dissolving in PBS. The change of surface voltage of the gold extended-gate electrode was about 30mV by IDS-VGS characteristic curve of the commercial MOSFET. Therefore, it is confirmed that the detection of CRP is possible by measuring the drain current of the commercial MOSFET. The proposed biosensor might open up a new possibility for FET-based biosensors with lowcost and simple construction. It is expected that the commercial MOSFET-based biosensor with the gold extended-gate electrode could also be used for detecting various biomarkers by modifying the surface of the gold extended-gate electrode.

  15. Performance evaluation of a capillary electrophoresis electrochemical chip integrated with gold nanoelectrode ensemble working and decoupler electrodes.

    PubMed

    Chen, Chun-Mao; Chang, Guan-Liang; Lin, Che-Hsin

    2008-06-20

    This paper presents a capillary electrophoresis poly(methyl methacrylate) (PMMA) based microchip for electrochemical detection applications featuring embedded gold nanoelectrode ensemble (GNEE) working and decoupler electrodes. In fabricating the microchip, the GNEE films are pressed directly onto the metallic electrode structures using a hot embossing technique, and the microfluidic channels are then sealed using a low-temperature azeotropic solvent bonding method. The detection performance of the microchip is evaluated using dopamine and catechol analytes for illustration purposes. The experimental results show that the GNEE working electrode provides a significantly higher signal response than that obtained from a bulk gold electrode when applied to the detection of dopamine analyte. Compared to a conventional bulk palladium decoupler electrode, the GNEE decoupler electrode reduces both the amplitude of the charge current (3.5 nA vs. 18.7 nA) and the baseline drift at higher separation voltages. The measured baseline current drift for the microchip equipped the proposed GNEE decoupler electrode is around three times smaller than the microchip with the palladium decoupler electrode under the applied separation electric field from 40 V/cm to 240 V/cm. Finally, when detecting a mixture of 1mM dopamine and 1mM catechol, the calculated signal response of the microchip with a GNEE decoupler electrode is approximately five times higher than that obtained from a microchip with a bulk Pd decoupler electrode, resulting in the detection limit of 1 microM for the proposed GNEE-based microchip device. Overall, the results indicate that the proposed capillary electrophoresis-electrochemical detection (CE-ED) microchip with embedded GNEE working and decoupler electrodes provides an ideal solution for sample detection in lab-on-a-chip and micro total analysis applications. PMID:18485353

  16. A combined current voltage sensor for metering and protection in high voltage power systems

    Microsoft Academic Search

    W. Z. Fam

    1994-01-01

    This paper describes a patented Poynting-vector transducer for the simultaneous measurement of both current and voltage in a high voltage power system. It also describes its application for protective relaying, high voltage metering, and measurement of losses in large transformers and shunt reactors. The principle of operation is based on the measurement of the Poynting vector from its constituent electric

  17. 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.

    2015-02-01

    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 (961.78° {C} ). 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.

  18. 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.

  19. Insulating electrodes: a review on biopotential front ends for dielectric skin-electrode interfaces.

    PubMed

    Spinelli, Enrique; Haberman, Marcelo

    2010-10-01

    Insulating electrodes, also known as capacitive electrodes, allow acquiring biopotentials without galvanic contact with the body. They operate with displacement currents instead of real charge currents, and the electrolytic electrode-skin interface is replaced by a dielectric film. The use of insulating electrodes is not the end of electrode interface problems but the beginning of new ones: coupling capacitances are of the order of pF calling for ultra-high input impedance amplifiers and careful biasing, guarding and shielding techniques. In this work, the general requirements of front ends for capacitive electrodes are presented and the different contributions to the overall noise are discussed and estimated. This analysis yields that noise bounds depend on features of the available devices as current and voltage noise, but the final noise level also depends on parasitic capacitances, requiring a careful shield and printed circuit design. When the dielectric layer is placed on the skin, the present-day amplifiers allow achieving noise levels similar to those provided by wet electrodes. Furthermore, capacitive electrode technology allows acquiring high quality ECG signals through thin clothes. A prototype front end for capacitive electrodes was built and tested. ECG signals were acquired with these electrodes in direct contact with the skin and also through cotton clothes 350 µm thick. They were compared with simultaneously acquired signals by means of wet electrodes and no significant differences were observed between both output signals. PMID:20834109

  20. Biased Electrodes for SOL Control in NSTX

    SciTech Connect

    Zweben, S. J. [Princeton Plasma Physics Laboratory (PPPL); Maqueda, R. J. [Nova Photonics, Princeton, NJ; Roqemore, A. L. [Princeton Plasma Physics Laboratory (PPPL); Bush, C. E. [Oak Ridge National Laboratory (ORNL); Kaita, R. [Princeton Plasma Physics Laboratory (PPPL); Marsala, R. J. [Princeton Plasma Physics Laboratory (PPPL); Raitses, Y. [Princeton Plasma Physics Laboratory (PPPL); Cohen, R. H. [Lawrence Livermore National Laboratory (LLNL); Ryutov, D. D. [Lawrence Livermore National Laboratory (LLNL)

    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.