Round Electrode Research Articles

Comparing cutaneous perception induced by electrical stimulation using rectangular and round shaped electrodes

Objective We have investigated the cutaneous perception differences for anodal and cathodal transcranial direct current stimulation (tDCS) and transcranial random noise stimulation (tRNS) between two electrode configurations: a standard, rectangle-shaped, and a circle-shaped, round geometry with the same surface area, and thus, same nominal current distribution. We have aimed to find whether a smaller perimeter length and the absence of corners in the case of the round configuration would lead to altered skin perception characteristics when compared to the rectangular geometry. Methods Twelve subjects were tested for tDCS and tRNS skin perception characteristics in the intensity range of 200–2000 μA using round and rectangular electrode configurations. Results We have not found any substantial differences between detection thresholds, detection rates, false positive rates or consistent alterations in the sites of perceived stimulation. Conclusion We conclude that there is no difference between the round and the rectangular electrode configurations regarding their blinding potentials. Significance The results of this investigation indicate that the altering of the electrode geometry to a round configuration is unwarranted for better blinding purposes in future studies using tDCS and tRNS.

Forcing mechanisms in supersonic flow actuation achieved by direct-current surface glow discharge plasma

Forcing mechanisms in aerodynamic flow actuation in Mach 3 supersonic flow provided by a direct-current surface discharge are investigated experimentally and computationally. High-speed flow actuation is achieved by creating a near-wall ionization region produced by striking a discharge between two bare round electrodes which are flush mounted on a ceramic actuator plate. Flow actuation which is signatured by the occurrence of a weak oblique shock originating from the ionization region is observed with a lower power ( ∼ 10 's W ) diffuse discharge which exhibits a volumetric ionization region above the cathode. This actuation effect is achieved when the cathode is placed upstream of the anode while no actuation is detected for the opposite case albeit with the same power input. Gas heating effect on flow actuation is evaluated by estimating gas (rotational) temperature using optical emission spectroscopy and numerical simulation. Significant gas heating as high as 400 K (free stream temperature is about 110 K) is observed near the cathode and numerical simulation confirms that gas heating is effective in supersonic flow actuation. However, the fact that the peak magnitude and spatial profile of gas temperature is similar for both cathode-upstream and cathode-downstream cases implies similar gas heating effect on supersonic flow actuation even though the actuation effect is different. Electrohydrodynamic (EHD) effect on flow actuation is emphasized by experimental results whose effect has been ignored in supersonic flow actuation and is supported by phenomenological modeling of electrostatic force. Analytic estimate of electrostatic forcing and corresponding computational result propose the potential role of EHD effect on supersonic flow actuation explaining the absence of flow actuation in the cathode downstream case.

Spatial harmonics of linear multipoles with round electrodes

The problem of creating hexapole, octopole, decapole and dodecapole electric fields with round-rod electrodes is considered. We propose a new numerical method to calculate the spatial harmonics and find the optimal electrode configurations. This configuration is characterized by the parameter γ = r/ r 0, where r is the rod radius and r 0 is the radius of an inscribed circle between the electrode tips. We consider four different criteria for optimizing the field: (1) the value that makes the amplitude of the main multipole 1.0, (2) the value that makes the amplitude of the next higher harmonic after the main harmonic zero, (3) the ratio that gives the next two higher harmonics equal amplitudes but opposite signs and (4) the ratio that minimizes the deviation of the potential and electric field from the potential and electric field of an ideal multipole, averaged over the region within the multipole. Each gives slightly different values for the optimal value of γ. To minimize the field deviation from that of an ideal multipole the optimal values are γ = 0.563, 0.372, 0.278, 0.221 for hexapole, octopole, decapole, and dodecapole fields, respectively.

A Flat Interface Nerve Electrode With Integrated Multiplexer

One of the goals of peripheral nerve cuff electrode development is the design of an electrode capable of selectively activating a specific population of axons in a common nerve trunk. Several designs such as the round spiral electrode or the flat interface nerve electrode (FINE) have shown such ability. However, multiple contact electrodes require many leads, making the implantation difficult and potentially damaging to the nerve. Taking advantage of the flat geometry of the FINE, multiplexers were embedded within the cuff electrode to reduce the number of leads needed to control 32 channels. The circuit was implemented on a polyimide film using off-the-shelf electronic components. The electronic module was surface-mounted directly onto the electrode's flat substrate. Two circuit designs were designed, built, and tested: 1) a single supply design with only two wires but limited to cathodic-first pulse and 2) a dual-supply design requiring three lead wires but an arbitrary stimulation waveform. The electrode design includes 32 contacts in a 1 mm x 8 mm opening. The contact size is 300 microm x 400 microm with access resistance less than 1 k ohm. This electrode is not intended for long-term use, but developed as a feasibility study for future development using low-water-absorption materials such as liquid crystal polymer and an application specific integrated circuit.

Cold Extrusion of Carbon Electrodes Using Dies of CRHS Concept and Performance Analysis

In this article cold extrution of carbon electrodes using the direct extrusion die that is designed using one of the theoretical concepts, Constancy of the Ratio of the Successive Generalized Homogeneous Strain-increment (CRHS), is presented. On the basis of the above concept we used three types of dies that are categorized as uniform (UCRHS),accelerated (ACRHS),and decelerated (DCRH) according to the deformation rates. All dies were with fixed reduction area of 50%. The mixture used (filler with binder) was extruded in round section carbon electrodes carried out at 60oC to 80oC. Ten samples are produced and tested for properties such as electrical resistivity, hardness, density and porosity. The results show that the extrusion die UCRHS is the more efficient die design for the production of carbon electrodes.

Phase measurement for electric field tomography

The basic principles of electric field tomography (EFT) are briefly explained. EFT system numerical simulation results are given. The comparison of images reconstructed by systems with planar and round electrode arrays is presented. Some aspects of transmitting and measuring stages are discussed. The accuracy of the phase-sensitive demodulator, which is the key element of an EFT measuring system, is evaluated experimentally.

EFFECT OF SIZE AND SHAPE OF ELECTRODES ON THE PERFORMANCE OF EDM

In the present study the effect of size and different shapes of electrodes on material removal rate (MRR), job surface finish and wear ratio (WR) during EDM has been investigated. The work material taken was mild steel and the electrode material taken was copper. The size of the electrodes was 9mm, 15 mm, 20 mm and 30 mm in diameter. The shapes of the electrodes were square, round, triangular and diamond, having the same area of cross-section. The highest MRR was found for round electrodes followed by square, triangular and diamond shaped electrodes. MRR was found to increases sharply with the increase in diameter of the electrodes. With increase in current, the sparks produced are of higher thermal energy. As a result, increase in current resulted increase in MRR. A higher thermal energy also erodes more material from the electrode. Electrode wear (EW) was measured along the crosssection of the electrode as well as along its length. EW was also found to increase with the increase in current. However, the highest EW was fond on the diamond shaped electrodes followed by triangular, square and the round shaped ones. An electrode of smaller cross-section exhibited a higher electrode wear. Wear ratio (WR) was calculated as the ratio of the volume of material removed from the electrode to the same removed from the work material. The highest WR was found on the diamond shaped electrodes followed by triangular, square and round electrodes. It was also found that WR decreases with increase in cross-sectional area of the electrode. Job surface roughness was found to decrease with increase in electrode diameter, but the effect is very insignificant. The smoothest job surface finish was found for round electrodes followed by square, triangular and diamond shaped electrodes. But again, the influence of the shape of the electrodes on job surface finish was found to be insignificant.

Optimization of the electrode shape of AlGaInP LED

The distribution of current diffusion of the quaternary AlGaInP LED has been simulated by finite element method to study the effect of electrode shape on the current spreading layer GaP. By comparing traditional circular-shape with cross-shape, arrow-shape, floriated-shape and gammadion-shape electrodes, we found that the electrode shape has an important effect on the output efficiency of light, and the light extraction efficiency of gammadion electrode is the highest. As the area of the whole electrode has an effect on the output efficiency, by optimizing the width of the electrode, the light extraction efficiency will be upgraded. For the gammadion electrode, when the width equals to 6.2204 μm, its light extraction efficiency is the highest, which is more than twice that of the traditional round electrode’s.

DETERMINATION OF SINGLE-DATE WATER CONTENT BY A NOVEL RF DEVICE

In Israel, ‘Madjhool’ has become the major date variety, thanks to its large size and pleasant appearance, which attract buyers who pay a price that is double or more than that of other varieties. However, this variety has a short shelf life and a tendency to develop “skin blisters.” Because of these limitations the growers plan to increase the proportion of fruit marketed as “Fresh Madjhool” – dates that are partially dried before delivery. The main physical property that has to be measured and controlled is fruit water content, and a novel instrument has been developed for this, based on the dielectric effect. Four round flat electrodes are manually positioned so that they touch the date and gently press on it. The electrodes and date constitute a unique capacitor. An RF signal is transmitted through the fruit, and its characteristics are correlated to water-content data. Calibration measurements with this instrument indicated an accuracy of ±2% wet basis (wb). This accuracy enables a representative accumulative distribution chart to be drawn, based on measurements on a sample of 50 fruits. On the basis of such charts several managerial quality decisions can be implemented. The device is controlled by a microprocessor that performs data collection and calculates the average water content of the measured sample. Four prototypes were built and have been tested in several warehouses, where they have yielded useful results.

Effect of ion entry acceptance conditions on the performance of a quadrupole mass spectrometer operated in upper and lower stability regions

Computer simulation of ion motion in a quadrupole mass spectrometer has been used to examine the effect of initial ion conditions on performance when operated in the first and third zones of the Mathieu stability diagram. Commercial instruments frequently use round electrodes instead of the better-performing hyperbolic electrodes because the cost of manufacturing is lower. However, adverse features are seen when using round electrodes. Here further insight is provided and a possible method of correction is suggested. For the first time, ion origin for the first stability region for a round electrode quadrupole has been reported.

Vibration induced hearing loss in guinea pig cochlea: expression of TNF-α and VEGF

Transcranial vibration was applied for seven animals at a frequency of 250 Hz for 15 min, and five animals were used as normal controls to investigate cellular and molecular mechanism linked to vibration-induced hearing loss in animal model. Compound action potential (CAP) thresholds were measured by round window niche electrode. The expression of tumour necrosis factor alpha (TNF-α) and its receptors (TNF R1, TNF R2), vascular endothelium growth factor (VEGF) and its receptors (VEGF R1, VEGF R2) were analysed by immunohistochemistry. Transcranial vibration caused expression of TNF-α, TNF R1 and TNF R2 in the cochlea and the expression of TNF R2 was stronger than that of TNF R1. Vibration also induced VEGF and VEGF R2 expression in the cochlea. The average immediate hearing loss was 62 dB and after three days still 48 dB. It is concluded that transcranial vibration as during temporal bone drilling produces cochlear shear stress that is connected with up-regulation of TNF-α and its receptors. Also VEGF and VEGF R2 are up-regulated. These responses may be linked to both the damage and repair process of the cochlea.

Ion-migration Polarity Change and 3D Shape Evaluation in the WDT Method

In this paper, protection resistance was measured as a parameter for the 3D shape of the dendrite, which was produced on the copper, printed wired board by the WDT method. The measurement was occurred using the 3D shape measurement system. We measured the 3D shape of a dendrite in a nonuniform electric field with a changing polarity. Moreover, the polar effect of ion-migration was examined by the 3D shape electric field analysis using ANSYS. Consequently, the height of the accumulation things at anode was higher than the negative pole side under round shaped cathode condition. Similarly, the quantity of the accumulation thing is also found larger at anode. On the other hand, the dispersal of the accumulation thing is observed between the anode and the negative pole under a round shaped anode conditions. And it turns out that there is also smaller accumulation thing at the tip part of a round shaped electrode. Moreover, for a same protection resistance, the amounts of generating of the accumulation objects per unit electric charge were larger for round shaped anode conditions comparing to the cathode. It is seen from 3d shape electric field analysis, that horizontal part of the electric field vector at anode is greater than the cathode. At the same time, the field intensity at anode is also larger than cathode. For a round shaped anode in 3D shape electric field analysis, the strongest electric field vector was found between a round shape electrode tip part and flat electrode. Although in the round shape cathode, the electric field vector had become the strongest between the flat electrode and the round shape electrode tip part. The electric field intensity of a nearby flat electrode was strong for a round shape electrode facing the field. Since the action states of the accumulation thing after a short circuit is different depending on the polarity of electrode for a nonuniform electric field conditions, it appears that it will not take much time to occur a failure

Calculation of Current–Voltage Curves and Angular and Transition Characteristics of a Round Electrochemical Sensor of Viscous Friction

The finite difference method is employed to solve three-dimensional equations of nonstationary convective diffusion for blank-ion concentrations. To correctly calculate the current density at the edge of a round electrode, the coordinate system of an oblate ellipsoid is applied. Kinetic boundary conditions valid for a redox reaction form at the surface of the sensor electrode.

Single-chip condenser microphone using porous silicon as sacrificial layer for the air gap

A single-chip IC-compatible silicon condenser microphone with a highly sensitive silicon nitride diaphragm and a rigid monocrystalline silicon counterelectrode with acoustic holes was designed and built. Porous silicon with its high dissolution rate in 1% KOH was used as an auxiliary sacrificial layer in combination with sputtered SiO 2 to define the air gap. This results in low parasitic capacitances and a microphone structure where the diaphragm is coplanar with its suspensions. The rigid backelectrode is undistorted, the diaphragm under low tensile stress, a prerequisite for high sensitivity. Microphones of different dimensions of round and square electrodes with single diaphragms and diaphragm arrays were built and packaged in round chip carriers. The open loop sensitivity is in the mV/Pa range depending on the type of microphone. The frequency response goes beyond 25 kHz for an air gap of 1.3 μm.

Chronic electrical stimulation by a cochlear implant promotes survival of spiral ganglion neurons after neonatal deafness

This investigation examined the consequences of neonatal deafness and chronic intracochlear electrical stimulation delivered by a cochlear implant during maturation. Kittens were bilaterally deafened by an ototoxic drug administered daily for 2 weeks immediately after birth. Unilateral electrical stimulation was initiated at 7-10 weeks of age and continued over periods of 22-47 weeks (4 hours/day; 5 days/week). Bipolar intracochlear electrodes delivered one of several different electrical signals designed to be temporally challenging to the central auditory system. Morphometric evaluation of spiral ganglion (SG) cell somata within Rosenthal's canal demonstrated a mean of approximately 50% of normal cell density maintained in the chronically stimulated ears, compared with approximately 30% on the control deafened side. This 20% difference in density was highly significant and was greater than differences reported in earlier studies using 30 pps stimulation delivered by either intracochlear bipolar or round window monopolar electrodes. However, the duration of stimulation was also longer in the present study, so it is unclear to what extent the nature of the temporally challenging stimulation vs. its duration contributed to the marked increase in survival. Measurements of the SG cell somata revealed a pronounced decrease in cell diameter in neonatally deafened cats studied about 1 year after deafening, and an additional decrease after long-term deafness (2.5-6.5 years). Furthermore, in the cochlear regions with the greatest stimulation-induced differences in SG cell density, direct measurements of cross-sectional soma area of the largest cells revealed that cells were significantly larger in the stimulated ears. Thus, in addition to the marked increase in the number of surviving SG cells, larger soma area contributed modestly to the pronounced increase in neural density following chronic electrical stimulation.

A new method for the calculation of magnetic fields

Abstract Magnetic fields in systems with unsaturated yokes can be favourably calculated by means of the boundary element method. This method consists in the formulation and numerical solution of integral equations for the potentials or field sources on the material surfaces. The different formulations of boundary value problems are finally always reduced to the task of solving a Fredholm equation with logarithmically singular integral kernel. A new technique is developed for the efficient and fast solution of such problems. It combines the Galerkin method of approximation — using interpolation kernels or modified Lagrange polynomials as test functions — with a partly analytical evaluation of the integral kernel. This technique, so far demonstrated for electrostatics, can now also be applied to magnetic systems with finite permeability of the yoke material. The feasibility of the method is demonstrated for some unconventional forms of magnetic lenses and for deflection systems. A further generalization is the field calculation in configurations of several round electrodes or pole pieces which are not aligned on a common optic axis but have arbitrary positions and orientations in space. The field calculation can be performed by an iterative solution of a sequence of coupled two-dimensional problems, which is much faster than a general three-dimensional procedure. Moreover, a hybrid technique for the field calculation in systems with saturated yokes, and finally a technique for studying small deviations from symmetries are briefly sketched.

Long-term treatment with chlorthalidone reduces experimental hydrops but does not prevent the hearing loss.

Long-term treatment of guinea pigs with the diuretics chlorthalidone and acetazolamide, following the experimental obstruction of the endolymphatic duct, was assessed using chronically implanted round window cochlear electrodes. The diuretic chlorthalidone appeared to curb the progressive low-frequency sensitivity loss during the first 4 weeks following surgery, as compared with animals receiving the diuretic acetazolamide or no treatment. However, this apparent beneficial effect decreased after 4 weeks and was not apparent at 14 weeks post-induction. On the other hand, morphological control at the end of 14 weeks confirmed a marked reduction in hydrops in the chlorthalidone-treated animals. The data clearly demonstrate a dissociation between hydrops and the development of hearing loss and suggest that the augmenting endolymph volume is only one of several contributing factors to the deteriorating auditory function in experimental hydrops.

Field Intensification Near Various Points of Contact with a Zero Contact Angle Between a Solid Dielectric and an Electrode

This paper describes the field intensification at the contact point in various arrangements where a rounded electrode contacts a solid dielectric at a zero contact angle. Three basic and two practical arrangements have been numerically analyzed for a variety of parameters.

Field Intensification Near Various Points of Contact with a Zero Contact Angle Between a Solid Dielectric and an Electrode

This paper describes the field intensification at the contact point in various arrangements where a rounded electrode contacts a solid dielectric at a zero contact angle. Three basic and two practical arrangements have been numerically analyzed for a variety of parameters.

Behavior of Sustained High-Current Arcs on Molten Alloy Electrodes during Vacuum Consumable Arc Remelting

Vacuum consumable arc remelting is a casting process carried out in a vacuum with the aim of remelting the consumable electrode in such a way that the new ingot has improved chemical and physical homogeneity. The power which causes the melting is supplied by a vacuum arc burning between the electrodes. In order to determine the furnace partitions of electrical power and current, experiments were conducted on molten-faced round electrodes. The quasi-steady melt rate was determined for both horizontally opposed 15-cm-diameter Ni electrodes and for vertically suspended 40-cm-diameter Inconel 718 electrodes. The cathode thermal power is directly proportional to the melt rate which, for the horizontally opposed electrode experiment, agrees to within 10 percent with the Ni breaker switch calorimetry measurements and with predictions from retarded potential analyzer plasma data. However, for the vertically suspended electrode experiments, the measured thermal power at the cathode is 50 percent higher than for nickel. When CO is introduced into the vertical alloy electrode system and electrode gap is increased, the cathode thermal power is reduced by approximately 50 percent. Furthermore, the electrode position measurements and observation of the ingot surface suggest that a concentrated arc is formed under these conditions.