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In this paper, the authors report rationally designed, innovative tri-layer flexible transparent conductive electrodes (TCEs) fabricated via thermal deposition. The proposed structure improves transparency compared with that of the traditional tri-layer electrode (dielectric/metal film/dielectric) by using metallic grid patterns (dielectric/metal grids/dielectric). The obtained MoO3/Ag grids/MoO3 TCEs show low sheet resistance and good mechanical properties. The sheet resistance of the proposed electrodes is 5.88 Ω/square and the transmittance reaches 76.5%, which are better than those of conventional MoO3/Ag film/MoO3 electrodes (6.12 Ω/square, <70%). The mechanical properties are significantly improved compared with those of MoO3/Ag film/MoO3 in the bending test under both tensile and compressive stress. The surface features of the MoO3/Ag grids/MoO3 TCEs were measured using the contact angle method to calculate the surface energy and polarity. The polarity is 0.5-0.26, which is better than those of indium tin oxide (0.35) and MoO3/Ag film/MoO3 (0.5-0.0058) electrodes for 0-800 bending cycles. The proposed flexible transparent electrodes show good optical, electrical, and mechanical characteristics and have potential for application in optoelectronics. [ABSTRACT FROM AUTHOR]

Preparation and characteristics of conductive-bridge random access memory devices containing Ge2Sb2Te5 (GST) chalcogenide as the solid-state electrolyte, Ag as the active electrode, and W-Ti as the counter electrode are presented. As revealed by the electrical measurement, only the samples containing crystalline GST exhibited the resistive switching behaviors. With an insertion of ZnS-SiO2 dielectric layer at the Ag/GST interface and a postannealing at 100?°C for 1?min, the sample exhibited the best electrical performance with satisfactory cycleability and retention properties. Moreover, the forming-free and bi-directional polarity features were observed in such a sample type. Microstructure and composition analyses found the finely dispersed nano-scale Ag clusters in GST and, when electrical bias is applied, the migrating Ag ions may build up the connections in between neighboring Ag clusters. Moreover, grain boundaries in polycrystalline GST might be the main paths for Ag migration. The thread-like conduction channels in GST hence form, leading to the low resistance state of sample. On the contrary, the depletion of Ag in GST broke the connections in between Ag clusters when the electrical bias is reversed. This led to the rupture of conduction channels and, hence, the high resistance state of sample. The low operational voltage, forming-free, and bi-directional polarity features observed in (AZGW)T sample might also originated from the fine dispersion of Ag clusters in GST electrolyte. [ABSTRACT FROM AUTHOR]

In this paper, positive, negative, and bipolar nanosecond pulses are employed to generate stable and diffuse discharge plasma using array needles-plate electrode configuration at atmospheric pressure. A comparison study of discharge images, electrical characteristics, optical emission spectra, and plasma vibrational temperature and rotational temperatures in three pulsed polarity discharges is carried on under different discharge conditions. It is found that bipolar pulse is beneficial to the excitation of diffuse dielectric barrier discharge, which can generate a room temperature plasma with more homogeneous and higher discharge intensity compared with unipolar discharges. Under the condition of 6mm electrode gap distance, 26 kV pulse peak voltage, and 150 Hz pulse repetition rate, the emission intensity of N2 (C3Πu → B3Πg) of the bipolar pulsed discharge is 4 times higher than the unipolar discharge (both positive and negative), while the plasma gas temperature is kept at 300 K, which is about 10-20K lower than the unipolar discharge plasma. [ABSTRACT FROM AUTHOR]

The aim of this research was to determine in which areas of the bovine body surface the electrodes should be placed to record T waves with stable polarity and morphology by using bipolar and unipolar leads to detect alterations in the conduction of the ventricular repolarization impulse. One hundred animals of both sexes from different age groups were used. Each T-wave form was numerically coded and its polarity was classified. Sixteen different forms of T waves were observed, presenting four types of polarity: positive, negative, biphasic +/- and biphasic -/+. In the bipolar shoulder lead IH, the T wave was largely negative or biphasic +/-; and it was positive or biphasic -/+ in the remaining bipolar leads. The T-wave was negative or in some cases biphasic +/- in the unipolar basal leads of the heart. Positive or biphasic polarity was always obtained in the apical leads -/+ and four to six different forms were recorded. It is concluded that, in the areas located towards the base or the apex of the heart, leads can be used originating electrocardiographic records with great stability in the polarity of the T wave and in which the quantity of different forms detected is very reduced, with great predominance of the pointed one, so that they become a very useful reference to diagnose the alterations in the conduction of the repolarization impulse through the cardiac ventricles. [ABSTRACT FROM AUTHOR]

The utilization of charged domain walls (CDWs) as nanoelectronic devices requires three technological aspects to be developed: (1) controllable CDW creation, (2) tuning of CDW geometry, and (3) CDW removal. We have studied CDW formation in lithium niobate single crystals during polarization reversal using liquid and solid-state electrodes, as well as their combination. It was shown that CDW can be formed by two alternative procedures: (1) by forward switching for the liquid electrode at the Z+ polar surface and solid at the Z− one, (2) by backward switching for solid at the Z+ polar surface and liquid at the Z− one. The created CDW can be transformed to an almost neutral domain wall by the application of the field pulse of the reverse polarity for both procedures. As a result, the tilt of the formed CDW can be tuned reversibly in the range from 0.2° to 1.2° resulting in a change between isolated and highly conductive states. We have demonstrated that the created CDW can be used as a nanoelectronic channel for local electrolysis opening the additional possibilities for ferroelectric lithography. [ABSTRACT FROM AUTHOR]

Neuronal excitability is determined in a complex way by several interacting factors, such as membrane dynamics, fibre geometry, electrode configuration, myelin impedance, neuronal terminations[Formula: see text] This study aims to increase understanding in excitability, by investigating the impact of these factors on different models of myelinated and unmyelinated fibres (five well-known membrane models are combined with three electrostimulation models, that take into account the spatial structure of the neuron). Several excitability indices (rheobase, polarity ratio, bi/monophasic ratio, time constants[Formula: see text]) are calculated during extensive parameter sweeps, allowing us to obtain novel findings on how these factors interact, e.g. how the dependency of excitability indices on the fibre diameter and myelin impedance is influenced by the electrode location and membrane dynamics. It was found that excitability is profoundly impacted by the used membrane model and the location of the neuronal terminations. The approximation of infinite myelin impedance was investigated by two implementations of the spatially extended non-linear node model. The impact of this approximation on the time constant of strength-duration plots is significant, most importantly in the Frankenhaeuser-Huxley membrane model for large electrode-neuron separations. Finally, a multi-compartmental model for C-fibres is used to determine the impact of the absence of internodes on excitability. Graphical Abstract Electrostimulation models, obtained by combining five membrane models with three representations of the neuronal cable equation, are fed with electrode and stimulus input parameters. The dependency of neuronal excitability on the interaction of these input parameters is determined by deriving excitability indices from the spatiotemporal model response. The impact of the myelin impedance and the fibre diameter on neural excitability is also considered. [ABSTRACT FROM AUTHOR]

This study examined the interaction between polarity and electrode-activation order on loudness in cochlear implant users. Pulses were presented with the polarity of the leading phase alternating or constant across channels. Electrode-activation order was either consecutive or staggered. Staggered electrode-activation orders required less current for equal loudness than consecutive orders with constant polarity. Consecutive electrode-activation orders required less current than staggered orders with alternating polarity. The results support the hypothesis that crosstalk between channels can interfere with or facilitate neuronal activation depending on polarity. [ABSTRACT FROM AUTHOR]

A thorough understanding of the governing concepts of polarity behavior within electroencephalograph (EEG) promotes analytical and thus technical proficiency of the technologist by providing a skill set to logically resolve the myriad of waveform presentations that are expected across all montage derivations. In addition to avoiding a reliance on cursory conceptualization techniques, a solid grasp of the underlying theory of EEG polarity permits a fundamental realization of the cause-effect relationships between the various directions of eye movement and the resulting multitude of wave deflection presentations observed across all montages. Such wisdom can logically account for the futility of using a particular bipolar montage to localize discharges of interest that are located at end-of-chain. Further, it provides a logical template from which to make sense of physiological and nonphysiological contamination within referential electrodes. Regardless of montage formatting, an EEG epoch can be deconstructed into discrete components; all of the left-sided electrodes within each pair of leads, or channel, are classified as input 1, whereas the right-sided ones are termed input 2. The Polarity Rule states that if input 1 is more negative with respect to input 2, there will be an upward deflection of the associated wave. All wave deflections within any montage arrangement can be explained from this core rule. For those expected to take examinations that include EEG polarity questions, this deeper appreciation may assist by shifting away from the need to memorize a plethora of scenario-dependent wave behaviors. [ABSTRACT FROM AUTHOR]

It is well known that after current interruptions, a fine Cu-Cr melted layer is formed on the electrode surface, and the vacuum insulation between electrodes is improved. However, the influence of the depth of the arc-melted layer on the vacuum insulation is still not clear. The objective of this paper is to determine the influence of the depth of the arc-melted layer of the cathode on the vacuum insulation. A 12 kV vacuum interrupter with a pair of rod-plane electrodes was designed. A DC current source was applied to the vacuum interrupter, and the rod electrode was chosen as the anode. A drawn vacuum arc in the anode spot mode was used to generate melted layers with different depths on the rod electrode. The arcing time was controlled to 0, 10, 46 or 73 ms. Then, the vacuum gap was adjusted to 1 mm to measure the basic lightning impulse breakdown voltage. Standard positive-polarity 1.2/50 μs lightning impulses were applied by a basic up-down method, in which the rod electrode was the cathode. Experimental results revealed that the breakdown probability followed a Weibull distribution when the breakdown voltage reached saturation. The 50% breakdown voltage U50 with arcing times of 0, 10, 46 and 73 ms was 55.6, 73.3, 75.5 and 77.9 kV, respectively. Next, a cross section of the rod electrode was analyzed using an electron microscope, and the average depths of the arc-melted layers were 0, 5, 35 and 65 μm at current arcing times of 0, 10, 46 and 73 ms, respectively. The depth of the arc-melted layer varied approximately linearly with the arcing time. The U50 values of the vacuum gaps with the arc-melted layers were significantly larger than that without a melted layer but very close to each other for all arc-melted layer depths. Thus, the melted layer did improve the breakdown voltage, but the depth of the arc-melted layer had little influence on the breakdown voltage. [ABSTRACT FROM AUTHOR]

One of the main reasons of metal film capacitors failure in pulse modes is a degradation of contacts between film metallization and solid electrodes—contact edges. This paper presents the results of experimental investigations of modeled contact edges behavior under current pulses of varying amplitude, duration, and quantity. It was found that the contact edge degradation is caused only by metallization destruction and independent on metal of the solid electrodes (“shoopage”). Depending on pulse parameters and dissipated energy in the contact edge, the contact erosion rate is in the range of (0.4– 2.7) \times 10^-3 g/J. Current pulse polarity effect on contact edge degradation was found: mean time to failure (MTTF) of the contact edge depends on its polarity, i.e., on the direction of the current flow through the contact during charge or discharge of capacitor. For different contacts polarities the difference between MTTFs reaches 20%–60% depending on pulse parameters. Based on these facts, one makes a supposition that the timely changing of the capacitor’s terminals polarity can lead to the increasing of capacitor lifetime. [ABSTRACT FROM PUBLISHER]

Electrical tree propagation is a precursor to dielectric failure in high voltage polymeric insulation. Tree growth has been widely studied under AC conditions, but its behavior under DC is not well understood. The aim of this work was to examine the importance of polarity and initiating defect size on DC tree propagation. Electrical tree propagation in epoxy resin under constant DC voltages of +60 kV and −60 kV was measured in samples with classical needle-plane electrodes, but with small initial trees (< 100 μm) incepted under lower AC voltages before the DC tests. Experimental results showed strong polarity dependence. In either polarity, the length of the initial AC tree had a major influence on the inception of the subsequent DC tree. The effect was attributed to the defect being influential if it is larger than the space charge injection region. As a consequence, there is a critical defect size that will accelerate failure of DC insulation dependent on space charge injection behavior of the polymer/electrode system in question — a critical finding for high voltage asset management. [ABSTRACT FROM PUBLISHER]

For the safe design and operation of wet-mate (WM) DC power connector, a time-dependent full thermo-electrodynamic model comprised of Poisson's equation, three charge continuity equations-one each for the positive and negative ions and one for the electrons-, and a thermal diffusion equation is developed to study the streamer initiation and propagation in the oil portion of a WM DC chamber. The electric field dependent molecular ionization mechanism accounts for the source term for free charge carriers, and positive ion/electron recombination, positive/negative ion recombination and electron attachment represent sink terms in the oil section. The solid portion of the WM DC connector is modeled as a perfect insulator. Considering a needle-sphere electrode geometry with electrodes covered by a dielectric solid and oil enclosed by the dielectric solid, it is approached the complicated solid-liquid insulation system envisaged in a WM DC connector after mating. By using the model, the influence of three parameters including magnitude and rise time of applied voltage as well as the type of oil on streamer initiation and propagation is investigated. It is found that the shorter rise time the more prominent streamer growth in the oil portion. For oil comprising only aromatics, an electric field magnitude larger than about 2×108 V/m is needed to propagate streamers, while this value for the oil comprising naphthenics/paraffinics will be exceeding 4×108 V/m. [ABSTRACT FROM PUBLISHER]

Purpose: Microchambers demonstrate anomalous voltage-dependent polarity effects. Existing polarity and ion recombination correction factors do not account for these effects. As a result, many commercial microchamber models do not meet the specification of a reference-class ionization chamber as defined by the American Association of Physicists in Medicine. The purpose of this investigation is to determine the cause of these voltage-dependent polarity effects. Methods: A series of microchamber prototypes were produced to isolate the source of the voltagedependent polarity effects. Parameters including ionization-chamber collecting-volume size, stem and cable irradiation, chamber assembly, contaminants, high-Z materials, and individual chamber components were investigated. Measurements were performed with electrodes coated with graphite to isolate electrode conductivity. Chamber response was measured as the potential bias of the guard electrode was altered with respect to the collecting electrode, through the integration of additional power supplies. Ionization chamber models were also simulated using COMSOL Multiphysics software to investigate the effect of a potential difference between electrodes on electric field lines and collecting volume definition. Results: Investigations with microchamber prototypes demonstrated that the significant source of the voltage-dependent polarity effects was a potential difference between the guard and collecting electrodes of the chambers. The voltage-dependent polarity effects for each prototype were primarily isolated to either the guard or collecting electrode. Polarity effects were reduced by coating the isolated electrode with a conductive layer of graphite. Polarity effects were increased by introducing a potential difference between the electrodes. COMSOL simulations further demonstrated that for a given potential difference between electrodes, the collecting volume of the chamber changed as the applied voltage was altered, producing voltage-dependent polarity effects in the chamber response. Ionization chamber measurements and COMSOL simulations demonstrated an inverse relationship between the chamber collecting volume size and the severity of voltage-dependent polarity effects on chamber response. The effect of a given potential difference on chamber polarity effects was roughly ten times greater for microchambers as compared to Farmer-type chambers. Stem and cable irradiations, chamber assembly, contaminants, and high-Z materials were not found to be a significant source of the voltage-dependent polarity effects. Conclusions: A potential difference between the guard and collecting electrodes was found to be the primary source of the voltage-dependent polarity effects demonstrated by microchambers. For a given potential difference between electrodes, the relative change in the collecting volume is smaller for larger-volume chambers, illustrating why these polarity effects are not seen in larger-volume chambers with similar guard and collecting electrode designs. Thus, for small-volume chambers, it is necessary to reduce the potential difference between the guard and collecting electrodes in order to reduce polarity effects for reference dosimetry measurements. [ABSTRACT FROM AUTHOR]

A comparative study of electrical breakdown properties of deionized water (H2O) and heavy water (D2O) is presented with two different electrode materials (stainless steel (SS) and brass) and polarity (positive and negative) combinations. The pulsed (~a few tens of nanoseconds) discharges are conducted by applying high voltage (~a few hundred kV) pulse between two hemisphere electrodes of the same material, spaced 3 mm apart, at room temperature (~26-28 °C) with the help of Tesla based pulse generator. It is observed that breakdown occurred in heavy water at lesser voltage and in short duration compared to deionized water irrespective of the electrode material and applied voltage polarity chosen. SS electrodes are seen to perform better in terms of the voltage withstanding capacity of the liquid dielectric as compared to brass electrodes. Further, discharges with negative polarity are found to give slightly enhanced discharge breakdown voltage when compared with those with positive polarity. The observations corroborate well with conductivity measurements carried out on original and post-treated liquid samples. An interpretation of the observations is attempted using Fourier transform infrared measurements on original and post-treated liquids as well as in situ emission spectra studies. A yet another important observation from the emission spectra has been that even short (nanosecond) duration discharges result in the formation of a considerable amount of ions injected into the liquid from the electrodes in a similar manner as reported for long (microseconds) discharges. The experimental observations show that deionised water is better suited for high voltage applications and also offer a comparison of the discharge behaviour with different electrodes and polarities. [ABSTRACT FROM AUTHOR]

Inverted polarity effect was studied at the breakdown of point-to-plane discharge gap filled with air at a pressure range of 0.013–0.3 MPa. High-voltage nanosecond pulses were applied to the electrode with a small radius of curvature. Pulser was operated at both negative and positive polarities in the single-pulse mode. Waveforms of voltage pulse, discharge current, and intensity of the discharge plasma radiation near the electrode with a small radius of curvature were registered. It was obtained that at the breakdown of point-to-plane discharge gap filled with air, the breakdown voltage at positive polarity of the pointed electrode was higher than that at negative one. The inverted polarity effect was shown to come to naught with an increasing of air pressure up to 0.3 MPa. It is suggested that the inverted polarity effect is related to the impeded formation of the explosive emission centers on the flat electrode (cathode) after arrival of the ionization wave front to the one. In addition, both the inverted and the ordinary polarity effects were not observed at the breakdown of nitrogen at pressures of 0.4 and 0.7 MPa. [ABSTRACT FROM PUBLISHER]

In this study, investigation of the unipolar resistive switching (RS) of InGaZnO film indicates that the reset voltage polarity can strongly affect the RS region. The dependence of the RS characteristics on the top electrode (Pt, Al, or Cu) was investigated. Asymmetrical electrodes (Cu/InGaZnO/Al) were chosen and the dependence of the RS parameters (e.g., high and low resistance states, set and reset voltages) on these two diverse electrodes can provide two indicators to trace the location of the RS region. The RS region is usually located near the anode when the applied set and reset voltages have the same polarity. In comparison, when the reset voltage has the opposite polarity to the set voltage, the RS region prefers to be located near the anode of the reset process rather than the cathode (which is used as the anode in the set process), indicating the movement of the RS region during the reset process. With the aid of joule heating, oxygen ions can overcome the energy barrier during the reset process under small voltage, resulting in the CFs restructuring and having the inverse shape, which is responsible for the drift mechanism of the RS region. [ABSTRACT FROM AUTHOR]

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We measured the impact of the thermoelectric effect, especially the Peltier effect, upon the operation of phase change memory (PCM) in which the contact resistance between the phase change material and the electrode dominates the total resistance. A PCM device having a pillar structure of diameter 500 nm was fabricated using GeCu2Te3 (GCT) material. During read operation, the set state (with crystalline PCM) showed ohmic contact between the PCM and the electrode, whereas the reset state (with amorphous PCM) showed Schottky contact. The Schottky contact between the amorphous GCT and the electrode showed a bias polarity dependence of set operation owing to the Peltier effect, which is one of the thermoelectric effects. As PCM devices scale down to the nanometre scale, research on contact resistance and various related effects will become more important. [ABSTRACT FROM AUTHOR]

This paper investigates the factors affecting the impulse characteristics of purposely built grounding systems. We installed 2 m × 2 m grounding systems in four different sites with different soil resistivity values. The effect of impulse polarity on soil characteristics was also investigated for different soil resistivity. A circular ring electrode was used as a return electrode in all four sites. For one of the sites, different configurations of grounding systems were installed to allow the study of the effect of ground electrode configurations on soil characteristics. The aim of this study was to quantify the effects of soil resistivity, impulse polarity, and earth electrode configurations on soil electrical properties under high impulse conditions by field measurements. The new data could be useful in understanding the characteristics of grounding systems in various factors under high impulse conditions. It is hoped that by considering these factors, it can help optimize the design of earthing systems. [ABSTRACT FROM AUTHOR]

The dynamics of an atmospheric pressure air discharge in a point-to-plane geometry with a dielectric layer obstacle on the discharge path is investigated numerically for different applied voltages. Whatever the polarity of the voltage applied, first, a streamer discharge of the same polarity ignites at the point and propagates towards the dielectric layer. After the impact on the dielectric surface, the streamer discharge spreads along the upper dielectric surface and charges it positively or negatively depending on its polarity. On the bottom surface of the dielectric layer, charges with an opposite polarity are deposited. Surface charges on both faces of the dielectric layer are shown to have a significant influence on the discharge reignition for a negative applied voltage, but not for a positive one. Furthermore, it is shown that the dynamics of the discharge reignition below the dielectric layer depends on the polarity of the applied voltage at the point electrode. For a positive applied voltage, the reignited discharge is a positive ionization wave propagating towards the grounded plane. For a negative applied voltage, a double headed discharge is observed with positive and negative fronts propagating in opposite directions. Finally, the minimal value of the ionization integral to have a discharge reignition below the dielectric obstacle is found to be less for a negative applied voltage than for a positive one. [ABSTRACT FROM AUTHOR]