Parallel Plate Electrodes Research Articles

Inactivation of Escherichia coli in Ice through DC electric field application and freezing

This study presents the effect of direct current (DC) electric field application on ice sterilization. The sample used was Escherichia coli (JM103) in a 0.001, 0.01, or 0.1 mol/L NaCl aqueous solution. The experimental sample was placed in a cuvette with parallel electrode plates (distance between electrodes: 1 mm) and then cooled at −30 °C or −80 °C for 40 min. After freezing, a 100 V DC voltage was applied to the sample in the freezer with a temperature of −30 °C or −80 °C. Consequently, the survival ratio of E. coli in all samples after freezing was lower than that before freezing due to the freezing injury. In conclusion, we found the bactericidal effect of the DC electric fields in the frozen 0.01 mol/L NaCl samples. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Electrical Characterization of Cellulose-Based Membranes towards Pathogen Detection in Water.

Paper substrates are promising for development of cost-effective and efficient point-of-care biosensors, essential for public healthcare and environmental diagnostics in emergency situations. Most paper-based biosensors rely on the natural capillarity of paper to perform qualitative or semi-quantitative colorimetric detections. To achieve quantification and better sensitivity, technologies combining paper-based substrates and electrical detection are being developed. In this work, we demonstrate the potential of electrical measurements by means of a simple, parallel-plate electrode setup towards the detection of whole-cell bacteria captured in nitrocellulose (NC) membranes. Unlike current electrical sensors, which are mostly integrated, this plug and play system has reusable electrodes and enables simple and fast bacterial detection through impedance measurements. The characterized NC membrane was subjected to (i) a biofunctionalization, (ii) different saline solutions modelling real water samples, and (iii) bacterial suspensions of different concentrations. Bacterial detection was achieved in low conductivity buffers through both resistive and capacitive changes in the sensed medium. To capture Bacillus thuringiensis, the model microorganism used in this work, the endolysin cell-wall binding domain (CBD) of Deep-Blue, a bacteriophage targeting this bacterium, was integrated into the membranes as a recognition bio-interface. This experimental proof-of-concept illustrates the electrical detection of 107 colony-forming units (CFU) mL−1 bacteria in low-salinity buffers within 5 min, using a very simple setup. This offers perspectives for affordable pathogen sensors that can easily be reconfigured for different bacteria. Water quality testing is a particularly interesting application since it requires frequent testing, especially in emergency situations.

Impedimetric Analysis of Trabecular Bone Based on Cole and Linear Discriminant Analysis

A spatially unambiguous characterization of electrical properties of osseous tissues is important for the therapy of osteopathy via electrical stimulation. Accordingly, the study aimed to characterize the highly inhomogeneous composition and structures of different anatomical regions of trabecular bone based on their electrical properties. The electrical properties of 64 porcine trabecular bone samples were analyzed in a parallel plate electrode configuration and compared with published results. Therefore, a novel method, combining traditional Cole model with a linear discriminant analysis (LDA), was developed to discriminate the different regions, i.e., femur head, greater trochanter, and femur neck. Possible mechanisms behind the distinction for different regions could be interpreted from both methods. Respective adjacent regions with similar structure and composition could be distinguished from statistically significant differences of Cole parameters, i.e., α (p < 0.01) and R∞ (p < 0.05). The latter was correlated especially with water content, indicating an association of individual differences in microstructures in particular with conductivity. Conversely, different regions were unambiguously discriminated with LDA based on permittivity or conductivity. Contributions to the discrimination were explicitly reflected by the coefficients of the derived LDA features. A clear distinction was obtained especially for a frequency response at 950 kHz. Moreover, predictions for the classification of unspecified samples assigned them correctly to their origin with a success of 92.9%. The combination of both methods offers the possibility for a spatially resolved and eventually patient specific discrimination and evaluation of bone tissues and their response to therapies, notably electrical stimulation.

Feasibility of electrochemical regeneration of activated carbon used in drinking water treatment plant. Reactor configuration design at a pilot scale

This work evaluates the feasibility of electrochemical regeneration of granular activated carbon used in drinking water treatment plants as a real alternative to thermal regeneration. Two pilot-plant-scale reactors, with a capacity of 10−15 kg, have been designed using two different configurations, parallel plate electrodes and concentric cylindrical electrodes. The optimization of the anode material has also been studied and Pt/Ti, RuO2/Ti and IrO2/Ti have been used. After the regeneration and, thus, recovery of the porosity the samples were tested in the adsorption of bisphenol A. In the electrochemical regeneration, recovery of the porosity of spent activated carbon until 100 % and 96 % with respect to the pristine activated carbon using Pt/Ti anode after 3 h of treatment, has been achieved. The regeneration process produces a small increase in the number of surface oxygen groups. No important differences have been observed among the tested anodes and RuO2/Ti and IrO2/Ti can be an economic alternative to Pt/Ti. Bisphenol A adsorption kinetics was slower in regenerated activated carbons probably due to the formation of surface oxygen groups. However, the adsorption capacity was similar in the regenerated samples and the pristine one.

Numerical Investigation of Dielectric Relaxation in Interacting Systems

Three dimensional dielectric systems are simulated to obtain the relaxational polarization responses. The dielectric system consists of randomly distributed permanent dipoles that fluctuate due to thermal activation in double well potentials between two plane-parallel electrodes. The barrier height between the wells is assumed to be proportional to the dipole length. The electrodes' effect is considered with the method of images. The relaxational phenomena of two dielectric systems, one with fixed and the other with distributed dipole lengths having single and distributed relaxation times, respectively, are calculated with a Monte-Carlo simulation method. The local field at every dipole and consequently the transition probabilities are computed to determine the transient polarization response iteratively. Both dielectric systems are simulated over a wide range of temperatures for interacting and non-interacting cases. The mean relaxation times exhibit a Vogel-Fulcher law for interacting systems and an Arrhenius law for non-interacting systems.

Electric Field and DC Breakdown Voltage of Multi-layer Dielectrics in Parallel-Plane Geometry

In this paper, the electric field, space charge and temperature distributions across a double layered dielectric are investigated under DC voltage. The dissimilarity of material properties of different layers, the effect of electric field and temperature dependent conductivity are found to play critical role in the electro-thermal problem of multi-dielectrics. At the interface, Maxwell-Wagner polarization is incorporated for electric field and interfacial charge, while temperature is considered as a continuous function of space inside the material. The current continuity equation, thermal continuity equation and Poisson's equation are simultaneously solved using numerical methods in parallel-plane electrode geometry. The electric field distribution, temperature distribution, space charge distribution and thermal breakdown limits are obtained at various boundary temperatures for different thickness proportions of layers.

Winter rye tolerance to low temperatures after seed treatment with surface barrier discharge

In this work, the experimental results of surface barrier discharge plasma products affection to winter rye seed germination at the initial stage of growth and seedling tolerance to low temperatures are shown. The treatment was carried out for 10, 60, and 180 s in the plane-parallel electrode system with sinusoidal voltage of 2.7 kV with frequency 4.4 kHz applied to the strip electrodes at a distance of 5 mm from each other. It is shown that the treatment has no effect on seed germinating ability. In 180 s exposure treatment mode the stimulation of 3-day seedling shoot and root system length occurs. The freeze tolerance response of two-stage cold hardened seedlings grown from treated seeds shows that both the exposure of seed and the freezing temperature affect on the formation of positive response.

Instability mechanism and discharge regime diagnosis of microthrusters based on plasma properties.

In order to make it possible to control the plasma state and predict the regime transitions via coupling optical and electrical diagnosis in aerospace engineering, we have experimentally investigated the regime transitions under 0.1-15 kPa with an input discharge power of 0-25 W in a parallel-plate electrode configuration. An abnormal glow discharge (AGD), filamentary discharge (FD), and arc discharge (AD) are distinguished using the voltage-current characteristics under different gas pressures. The electron excitation temperature (Te), electron density (Ne), spatial resolutions of Te and Ne, and ionization degree are obtained via optical emission spectroscopy to reveal the transition mechanisms. Thermal instability, characterized by Te, plays a dominant role during the transition from an AGD to an FD. The conclusions are supported by analysis of ionization degree, whereas electronic instability becomes the dominant mechanism in the transition from an FD to an AD. This is related to collision kinetics because of an observed drop in Ne, which is verified by the spatial resolution as well. Moreover, planar laser-induced fluorescence provides further insight into the instantaneous location and relative number variation of Ar 1s5 metastable atoms, which agrees well with the plasma properties mentioned above. In addition, a pressure of 1 kPa with a maximum input power of 17.5 W are specified as suitable working parameters for further study when applied to microthrusters due to its higher Ne and better stability.

Potential and Current Distribution in an Electrochemical Cell- a Simulation Study

One of the prerequisites in all electrochemical processes is to achieve uniform distribution in potential and current acoss the electrodes and the cell. Although parallel plate electrodes encompass a preferable uniformity in distribution, it tends to get attenuated based on the geometric variables like electrode spacing and width of electrrodes. The purpose of this paper is to analyse underlying aspects associated with these distributions and to indicate how they can be visually represented. A mathematic treatment is carried out to generate an expression for electrolyte potential at the electrode surface with varying ratio of width of electrode to electrode spacing (L/H). Segregation of L/H, where improved uniformity could be attained, is evaluated based on a graphical study. In the latter part, simulation studies were conducted to examine the profile of both current and potential in a typical parallel plate electrochemical cell so as to get a visual representation. This study is proposed to be a cornerstone for practicing electrochemical engineers in designing electrodes and electrochemical cells for various applications.

Design of Electrohydrodynamic Devices with Consideration of Electrostatic Energy.

The importance of actuators that can be integrated with flexible robot structures and mechanisms has increased in recent years with the advance of soft robotics. In particular, electrohydrodynamic (EHD) actuators, which have expandable integrability to adapt to the flexible motion of soft robots, have received much attention in the field of soft robotics. Studies have deepened the understanding of steady states of EHD phenomena but nonsteady states are not well understood. We herein observe the development process of fluid in a microchannel adopting a Schlieren technique with the aid of a high-speed camera. In addition, we analyze the behavior of fluid flow in a microchannel that is designed to have pairs of parallel plate electrodes adopting a computational fluid dynamics technique. Results indicate the importance of considering flow generated by electrostatic energy, which tends to be ignored in constructing and evaluating EHD devices, and by the body force generated by the ion-drag force. By considering these effects, we estimate the development process of EHD flow and confirm the importance of considering the generation of vortices and their interactions inside the microchannel during the development of EHD devices.

Design of Conductive Coupler for Underwater Wireless Power and Data Transfer

Realizing capacitive coupling under seawater is difficult, although the capacitive coupler attracts attention as a promising solution for wireless power and data transfer. The coupler consisting of parallel-plate electrodes (e.g., capacitive coupler) has strong conductive coupling because of the high conductivity of seawater. This study introduces the design of a highly efficient coupler utilizing this phenomenon as a novel method. First, the operational principle of the highly efficient conductive coupler is clarified by comparing it to a conventional conductive coupler. The results reveal the key factor for the high-efficiency design. The design parameters at the maximum available efficiency are derived. The designed coupler is then fabricated. A demonstration shows that the efficiency of over 90% under seawater is achieved at a 20-mm transfer distance and a 1-kW transfer power. The demonstration also shows that power is wirelessly transferred to a camera module via the coupler, with the transferred data recorded by the camera appearing on a laptop computer.

REDISTRIBUTION OF SPUTTERED MATERIAL IN A PLANE IONPLASMA SYSTEM WITH AN ABNORMAL GLOW DISCHARGE

The redistribution of the flow of sputtered material of a target (cathode) between the collector and the target in a plane-parallel electrode system with an anomalous glow discharge is analyzed in the kinetic approximation. Sputtering is the result of bombardment of the target by gas ions accelerated in the near-cathode space charge layer and by fast neutral atoms formed as a result of resonant ion charge exchange. Sputtered atoms partially return to the target due to collisions with gas molecules. The formulas were obtained, which were confirmed in the experiment that makes it possible to correctly estimate the ratio of the sputtered material flows deposited on the collector and the target. The results of the work are used to calculate the parameters of the processes of coating deposition and ion cleaning of the target under conditions of the anomalous glow discharge.

Extremely low-frequency electric field suppresses not only induced stress response but also stress-related tissue damage in mice

Although extremely low-frequency electric fields (ELF-EF) have been utilised for therapeutic purposes, the biological effect and the underlying mechanism of ELF-EF have not been elucidated. Here, we developed a mouse model of immobilisation-induced increase in glucocorticoid (GC) to evaluate the effect of ELF-EF. Mice were exposed to 50-Hz 10 kV/m EF via a parallel plate electrode and immobilised as needed. The ELF-EF suppressed the immobilisation-induced increase in blood GC level. Here, the results of 32 tests using the model were pooled and analysed. The suppressive effect of ELF-EF on immobilisation-induced increase in GC was reproduced, and the GC level was slightly higher in the ELF-EF-treated mice than in the sham-controlled mice, a novel observation. The immobilisation-induced increase in lactate dehydrogenase, glutamic oxaloacetic transaminase, and glutamic pyruvic transaminase, markers of tissue damage, was suppressed by co-treatment with EF in the biochemical tests using the same plasma sample. In the metabolome analysis, the changes in corticosterones, leukotrienes, and hydroxyeicosatetraenoic acids, markers of inflammation, showed a pattern similar to that of the plasma GC level. Thus, ELF-EF suppresses the stress response that causes an increase in the GC level and slightly promotes GC production in the absence of stress. Moreover, the suppressive effect of ELF-EF on induced stress response might be involved in stress-induced tissue damage or inflammation in immobilised mice. Overall, the model and the data help explore the biological effect of ELF-EF and explain the stress-relieving effect of EF. They would be useful in determining the medical applications of EF in humans and animals.

Large-Stroke Capacitive MEMS Accelerometer Without Pull-In

In this study, the feasibility of obtaining electrical read-out data from a capacitive MEMS accelerometer that employs repulsive electrode configuration is demonstrated. This configuration allows for large-stroke vibrations of microstructures without suffering from pull-in failure that exists in conventional accelerometers based on the parallel-plate configuration. With initial fabrication gap of 2.75μm, the accelerometer can reach a 4.2μm dynamical displacement amplitude. The accelerometer is tested up to 95(V) without exhibiting pull-in failure. For comparison, the pull-in voltage of an accelerometer with same dimensions but with conventional parallel-plate electrode configuration is 0.8(V). The MEMS device is fabricated using the POLYMUMPs fabrication standard. An electrical circuit is built to measure the capacitance change due to motion of the accelerometer proof-mass. The accelerometer has a mechanical sensitivity of 35nm/g and electrical sensitivity of 5.3mV/g. The ability to use large bias voltages without the typical adverse effects on the stability of the moving electrode will enable the design of capacitive MEMS accelerometers with enhanced resolution and tunable frequency range.

Effect of constant high-voltage electric field on wheat seed germination

In this work an effect of the 10-min pre-sowing treatment by the constant electric field with the 3 kV cm−1 electric field strength on the soft spring wheat seed germination is studied at various positions of the seeds in a plane-parallel electrode system. The effects of the electric field direction and contact conditions of the seeds with a plane aluminum electrode (no contact, when the seeds lie on the isolating plate; contact with the positive or negative high-voltage or grounded electrode) are compared. The treatment response is estimated by the morphological characteristics of 3-day seedlings—germination, the shoot length and the length of individual roots. At all modes, the treatment does not change seed germination. At each considered variant of seed location, the electric field effect did not reduce the average length of the root system and the shoot length below the ones at the control variant. The significant increase of morphological characteristics is achieved at the seed contact with the high voltage electrode.

Single and ensemble response of colloidal ellipsoids to a nearby ac electrode

Anisotropic colloids can be used as building blocks for fabricating assemblies with complex microstructure and function. External electric fields are one key tool used to assemble such colloidal structures. Herein, we utilized a parallel plate electrode geometry to drive motion of micrometer scale ellipsoidal colloids. The response of pseudo 2D layers of ellipsoids with systematically altered aspect ratios was measured as a function of electric field strength and frequency. We found there to be a weak dependence of ellipsoid ensemble structure on aspect ratio. Namely, regions of aggregation and separation were only slightly dependent on particle aspect ratio. We found that ellipsoids with a smaller aspect ratio tended to align with the electric field, while high aspect ratio ellipsoids did not in response to an electric field of the magnitude and time scale used herein. In addition, we found the kinetics of aggregation of colloids to be very similar regardless of aspect ratio. Complementary experiments utilizing these data demonstrated long-lasting deposition of ellipsoids in energetically unfavorable orientations, which is being used as a model system for the measurement of light scattered from an evanescent wave by an ellipsoid.

Low-cost capacitive sensor for detecting palm-wood moisture content in real-time

sIn this study, we analyze a non-invasive and low-cost wood moisture meter by means of a capacitive detection circuit. The process of the design and development of an oil-palm-wood moisture meter is described. As part of the study, two electrode structures, i.e., parallel-plate and coplanar electrodes, are tested. The capacitive detection circuit includes a square-wave-generator circuit, low-pass filter circuit, and signal-conditioning circuit. The frequencies of the square-wave excitation signal are in the range of 200 kHz and are analyzed via a microcontroller to interpret the percentage of oil-palm-wood moisture content. The applicability of the capacitive moisture measurement is investigated under various moisture conditions of the oil palm wood i.e., 5%–20%. The experimental results show that the measurement accuracy of the detection circuit is high, with an acceptable measurement error.

Simulations of fluid flow, mass transport and current distribution in a parallel plate flow cell during nickel electrodeposition

Abstract A laboratory filter-press flow cell with parallel plate electrodes is designed for nickel electrodeposition on mild steel from a diluted solution. Design features, such as electrolyte manifolds and turbulence promoters, produced by 3D printing, following computational fluid dynamics (CFD) simulations, are used to minimize jet flow and edge effects on current density. A hydrodynamic analysis is performed by solving the Reynolds averaged Navier-Stokes (RANS) equations with the k − e turbulence model. The averaged convective-diffusion equation is solved for mass transport simulations, while wall functions are used to simulate tertiary current distribution considering the side reaction of hydrogen evolution (HER). The flow cell design minimizes electrolyte flow and current density edge effects at the entrance to the cell by using an electrolyte manifold followed by polymer mesh turbulence promoter and a flow calming zone before the reaction region of the flow channel. The experimental validation of nickel electrodeposition agrees with the predicted tertiary current distribution profiles.

A computational study of negative surface discharges: Characteristics of surface streamers and surface charges

We investigate the dynamics of negative surface discharges in air through numerical simulations with a 2D fluid model. A geometry consisting of a flat dielectric embedded between parallel-plate electrodes is used. Compared to negative streamers in bulk gas, negative surface streamers are observed to have a higher electron density, a higher electric field and higher propagation velocity. On the other hand, their maximum electric field and velocity are lower than for positive surface streamers. In our simulations, negative surface streamers are slower for larger relative permittivity. Negative charge accumulates on a dielectric surface when a negative streamer propagates along it, which can lead to a high electric field inside the dielectric. If we initially put negative surface charge on the dielectric, the growth of negative surface discharges is delayed or inhibited. Positive surface charge has the opposite effect.

Influence of Drying Rate on Hot Air Drying Processing of Fresh Foods Using Pulsed Electric Field

Influence of pulsed electric field (PEF) on the drying rate of foods during the hot air drying process is investigated. Nine kinds of fruits and vegetables and two kinds of marine products are used as the samples, and changes in the weight of these samples during the process are evaluated. PEF is applied to the samples using parallel plate electrodes. The applied voltage ranges from 0.4 to 3 kV, and the input energy of the sample ranges from 1.5 to 115.5 J/g. The samples are dehydrated using a hot air dryer after the PEF treatment. The drying rate of leafy vegetables, apples, and wakame seaweed is accelerated by PEF. The results show that the moisture permeability of membrane can be improved by destroying the cell membrane by PEF. On the other hand, there is no effect on root vegetables because their hard tissues are hard to destroy. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.