Cylindrical Electrodes Research Articles

Differences in the Electric Field Distribution Predicted with a Mathematical Model of Cylindrical Electrodes of Finite Length vs. Infinite Length: A Comparison Based on Analytical Solution

Cylindrical-shaped metal electrodes are used in numerous medical specialties to force an electric field into the surrounding tissue (e.g., in electrical stimulation and electroporation). Although these electrodes have a limited length in reality, previous mathematical modeling studies have simplified the physical situation and have built a model geometry based on a cylindrical electrode of infinite length, which allows for reducing the model from 2D to 1D. Our objective was to quantify the differences in the electric field values between the finite and infinite electrode cases and assess the adequacy of the mentioned simplification for different values of electrode diameter and length. We used analytical solutions for the electric field distribution. We found that the electric field distribution is substantially different for both cases, not only near the edges of the electrode (when finite length is assumed) and in close locations (<1 mm), but even in the central area and at distances greater than 2 mm. Our work presents analytical solutions for both cases (finite and infinite length), which, despite the oscillations derived from computational limitations, could be used by researchers involved in electric field modeling in biological tissues, in order to quantify the possible error generated with simple models in geometric terms that assume infinite length.

Cylindrical hot cathode ionisation gauge – The concept and simulations

A novel design of an ionisation vacuum gauge is presented, aiming to achieve predictable sensitivity and high accuracy in high and the ultra-high vacuum range. The proposed design features a belt-like electron beam emitted from a linear filament, following a circular trajectory between two cylindrical electrodes, resembling a cylindrical analyser. The proposed design offers several key upsides: a precisely defined electron beam trajectory with reduced susceptibility to path variations, effective electron collection in a Faraday cup able to contain secondary emissions and backscattered electrons, and the inclusion of a suppressor grid in front of the ion collector to eliminate ion-induced secondary electron emission. These features are expected to secure high stability of the gauge and the low pressure limit. An in-depth description of the design is presented, along with the discussions on simulations of the key components that provide the improved performance.

Using dielectrophoretic spectra to identify and separate viable yeast cells.

Immotile yeast cells were transiently moved in nonuniform sinusoidal electric fields using multiple pairs of micro-parallel cylindrical electrodes equipped with a sequential signal generator (SSG) to analyze cell viability at a clinical scale for the brewery/fermentation industry. Living yeast cells of Saccharomyces cerevisiae during the exponential-stationary phase, with a cell density of 1.15 × 105 cells mL-1 were suspended in sucrose medium. The conductivity (σs) was adjusted to 0.01 S m-1 with added KCl. Cells exposed in electric field strengths ranging from 32.89 to 40.98 kV m-1, exhibited positive dielectrophoresis (pDEP) with the lower critical frequencies (LCF) at 85.72 ± 3.59 kHz. The optimized value of LCF was shifted upwards to 780.00 ± 83.67 kHz when σswas increased to 0.10 S m-1. Dielectrophoretic and LCF spectra (translational speed of cells vs. electric field frequencies) of yeast suspensions during positive dielectrophoresis were analyzed in terms of the dielectric properties of the cell membrane and cytoplasm which reflect yeast cell viability and metabolic health status. The dielectrophoretic collection yield of cells using positive dielectrophoresis was reported on the monitor of sequential signal generator software to evaluate the number of living and dead cells through a real-time image processing analyzer. The spectra of both positive dielectrophoresis of the living and dead cells had distinguishable dielectric properties. The conductivity of the yeast cytoplasm (σc) of the dead cells was significantly less (≈ ≤ 0.05 S m-1) than that of the living yeast cells which typically had a cytoplasmic conductivity of ≈ 0.2 S m-1. This difference between viable and non-viable cells is sufficient for cell separation procedures. KEY POINTS: • Dielectrophoresis can be used to separate viable and non-viable yeast cells, • Cellular dielectric properties can be derived from the analysis of their dielectric spectra, • Cytoplasmic conductivity of viable cells is ≈ 0.2 S m-1 while that of non-viable cells ≈ ≤ 0.05 S m-1.

Generation of stabilized electrically-induced micro-plasma at the tip of multimaterial optical fibers

The aim of this work is to optimize the operation of a multimaterial optical fiber device to generate a stabilized electrically-induced micro-plasma. The fiber is composed of a polymer cladding with a central hole surrounded by two cylindrical metal electrodes. When a DC voltage of 1.2 kV is applied between electrodes, an air micro-plasma is generated at the tip of the fiber. In order to stabilize the discharge, studies are focused on the modification of the electrical properties of the fiber tip by covering the electrodes with resistive layers. A comparison between two different layers (semi-conductive and semi-insulating) is shown. Characterizations were also performed for the fiber (head and length), and the plasma (imaging, spatial and temporal stability). The results show the effectiveness of the method to cover at least one of the electrodes by the semi-insulating layer to generate a permanent and stable discharge. In fact, this method allowed to increase considerably the lifetime of our technology and avoid the electric arcs leading to high instabilities. According to the Optical Emission Spectroscopy (OES), the species generated by the fiber-plasma device were identified.The combination of the characteristics of optical fibers with the properties of plasma allows diverse potential applications, such as gas detection in remote, confined, or harsh environments, high-level disinfection and sterilization of medical equipment or high-quality surface treatment (micrometric scale).

Synthesis and characterization of cylindrical electrode with sucrose binder as advanced electrode materials for copper 3D-electro-oxidation.

This study produced a biomass-based cylindrical electrode containing sucrose (an organic binder). The Cu2+ removal performance of the synthesized sucrose-bonded cylindrical electrode was evaluated in a 3-phase 3-dimensional electro-oxidation reactor (3D-EO) and the classical electro-oxidation method (2D-EO). Sodium Dodecyl Sulfate (SDs) was grafted onto activated carbon and used as microelectrode in 3D-EO reactors. SDs grafting resulted in a 57% reduction in the micropores of activated carbon. Therefore, the surface area of carbon after grafting decreased from 1328 m2/g to 580 m2/g. The sucrose-bonded cylindrical electrode has a rich carbon structure and consists of 84.04 wt% C, 12.10 wt% O and 3.20 wt%Si. According to CV measurement, the sucrose-bonded cylindrical electrode gives a surface reaction against Cu2+ at voltages lower than -0.62 V. Increasing the potential difference from 1V to 3V in 2D-EO and 3D-EO processes led to the removal of Cu2+ from the solution. The 3D-EO reactor achieved a removal rate of 87.12% at 3V. The 100 ppm solution was treated with a 3D-EO reactor containing 6 g/L of PC/SDs400Ws for 60 min, successfully removing 91.22% of Cu2+.

Hydrophobic Gating and Spatial Confinement in Hierarchically Organized Block Copolymer-Nanopore Electrode Arrays for Electrochemical Biosensing of 4-Ethyl Phenol.

Hydrophobic gating in biological transport proteins is regulated by stimulus-specific switching between filled and empty nanocavities, endowing them with selective mass transport capabilities. Inspired by these, solid-state nanochannels have been integrated into functional materials for a broad range of applications, such as energy conversion, filtration, and nanoelectronics, and here we extend these to electrochemical biosensors coupled to mass transport control elements. Specifically, we report hierarchically organized structures with block copolymers on tyrosinase-modified two-electrode nanopore electrode arrays (BCP@NEAs) as stimulus-controlled electrochemical biosensors for alkylphenols. A polystyrene-b-poly(4-vinyl)pyridine (PS-b-P4VP) membrane placed atop the NEA endows the system with potential-responsive gating properties, where water transport is spatially and temporarily gated through hydrophobic P4VP nanochannels by the application of appropriate potentials. The reversibility of hydrophobic voltage-gating makes it possible to capture and confine analyte species in the attoliter-volume vestibule of cylindrical nanopore electrodes, enabling redox cycling and yielding enhanced currents with amplification factors >100× when operated in a generator-collector mode. The enzyme-coupled sensing capabilities are demonstrated using nonelectroactive 4-ethyl phenol, exploiting the tyrosinase-catalyzed turnover into reversibly redox-active quinones, then using the quinone-catechol redox reaction to achieve ultrasensitive cycling currents in confined BCP@NEA sensors giving a limit-of-detection of ∼120 nM. The mass transport controlled sensing platform described here is relevant to the development of enzyme-coupled multiplex biosensors for sensitive and selective detection of biomarkers and metabolites in next-generation point-of-care devices.

Electrocoalescence of W/O emulsions in electric fields generated by matrix electrodes

Waste oil resource treatment can avoid its pollution of the ecological environment, in which the demulsification and dehydration of water-in-oil (W/O) emulsions is crucial for waste oil resource treatment. Electrocoalescence technology has been attracting much attention as a fast-developing emulsion breaking and separation technology with a short development time. In this study, a non-uniform matrix electrode structure is proposed, the effects of a non-uniform matrix electrode on emulsion demulsification and dehydration are investigated experimentally, and the relative benefits of a matrix electrode and a traditional electrode structure are compared and analyzed. According to experimental results, the matrix electrode's dehydration effectiveness at U = 1000 V was 1.59 and 1.29 times greater than that of the parallel plate and coaxial cylindrical electrodes, respectively. The best electric field parameter setting was U = 1100 V, f = 2500 Hz, and δ = 0.5. After electrocoalescence, the water content was 0.60 % and the dehydration efficiency was 94.00 %. This work presents innovative ideas for the design of small and efficient electric coalescers as well as beneficial information for selecting the right electric field parameter. It is conducive to optimizing the resourceful recycling and treatment technology of W/O waste oil.

Dendritic propagation on circular electrodes: The impact of curvature on the packing density.

The dendritic growth in rechargeable batteries is one of the hurdles for the utilization of high energy-density elements, such as alkaline metals, as the electrode. Herein we explore the preventive role of the curved electrode surface in the cylindrical electrode design versus the flat geometry on the stochastic evolution of the dendritic crystals. In this regard we establish a coarse-grained Monte Carlo paradigm in the polar coordinates (r,θ), which runs in a larger scale of time and space (∼μs,∼nm ) than those of interionic collisions (∼fs, Å). Subsequently we track the density and the maximum reach of the microstructures in real time, and we elaborate on the underlying mechanisms for their correlation of the relative dendrite measure with the electrode curvature. Such quantification of the positive impact of the curvature on suppressing dendrites could be utilized as an effective longevity design parameter, particularly for the cases prone to dendritic propagation.

Evaluation of a novel electrode design for high voltage pulse ore pre-concentration

High Voltage Pulse (HVP) enabled ore preconcentration has the potential to provide large energy savings and upgrade Run-of-Mine ores. The concept is well established in laboratory settings but is yet to be demonstrated at the throughputs needed for industrial uptake of the technology. To scale up this concept from laboratory batch tests to a continuous operation, a novel grizzly-electrode design that integrates pulse discharges for particle breakage and size-based separation into a single step has been patented. In the initial evaluation of the system, two cylindrical electrode bars were adopted with an experiment design to simulate continuous feeding operation. Synthetic particles and a low-grade gold-copper ore were used for the initial evaluation. The evaluation showed pre-concentration can be achieved. Factors affecting the system performance were identified and limitations of the grizzly electrodes are discussed.

3D printed cathodes for implantable abiotic biofuel cells

3D printing has recently triggered huge attention in several fields such as construction, artificial tissue engineering, food fabrication, wearable electronics, and electrochemical energy storage.This work investigates the fabrication of a 3D-printed abiotic cathode for implantable glucose/oxygen biofuel cells. The ink formulation was optimized to get printable ink with high electro-catalytic activity. Electrode macro porosity was screened in order to identify the better compromise between electrode density and electrochemical performance. A maximum current density of 260 μA/cm2 was obtained with cylindrical electrodes with linear mesh infill and a volumic infill rate of 40%.A complete biofuel cell was assembled using a 3D-printed abiotic cathode and an enzymatic anode in the form of a compressed pellet showing maximum power and current densities of 80 μW/cm2 and 320 μA/cm2, respectively. Moreover, the hybrid biofuel cell was implanted in the intraabdominal region of a rat for three months and after cell explantation, the abiotic cathode displayed a 50% decrease in the current density while the enzymatic anode did not display any residual activity.The 3D printed electrode displayed a 2–3.6 fold increase in current density when compared to homolog 2D electrodes.

A high resolution differential mobility analyzer for the study of large virus particles

The conical inner electrode of a recently described differential mobility analyzer (DMA), covering at resolution >50 the size range up to 60 nm, has been modified by increasing its radius at the outlet slit from 1 cm to 1.6 cm, and decreasing its convergence angle from 3° to 0.5°. The cylindrical outer electrode radius is maintained at 2 cm, while other critical dimensions are only slightly modified. The classification voltage for fixed flow rate of sheath gas and particle diameter decreases almost fourfold, extending the size range theoretically spanned at high resolution well beyond 120 nm. Tests with multiply charged polystyrene latex spheres 200 nm in diameter confirm the actual ability to cover this wide size range. A resolution above 100 (with no corrections for instrument or particle nonidealities) is demonstrated with rotavirus double-layered particles (DLP) whose mobility diameter is found to be near 60 nm. The DLP has several configurations that complicate its use for DMA characterization, but occasionally presents mainly one conformer, with singularly narrow relative mobility width FWHM < 1/150. Two broad range instruments with slightly different axial lengths have been developed and tested, both reaching resolving powers of 100.

Properties of the multipole fields formed by round electrodes

The aim of the work is to study the properties of multipole electric fields formed by round rods. We consider the problem of finding the convergence radius of the series obtained by expansion of the potential into spatial harmonics, as well as the calculation of the complex potential for the case of the optimal configuration of cylindrical electrodes. A method is given for finding the real potential, which allows to obtain expansion of potential into power series with high precision.

Parametric optimization of hexavalent chromium removal by electrocoagulation technology with vertical rotating cylindrical aluminum electrodes using Taguchi and ANN model.

This study aims to evaluate the performance of rotating aluminum electrodes in the electrocoagulation reactor for removing hexavalent chromium (Cr6+) from synthetic tannery wastewater. Taguchi and Artificial Neural Network (ANN) based models were developed to obtain the optimum condition for maximum Cr6+ removal. The optimum working condition obtained by Taguchi approach for the maximum Cr6+ removal (94%) was: Initial Cr6+ concentration (Cr6+ i) = 15mg/L; Current Density (CD) = 14.25mA/cm2; Intial pH = 5; Rotational Speed of Electrode (RSE) = 70rpm. In contrast, the optimal condition for maximum Cr6+ ions removal (98.83%) obtained from the BR-ANN model was: Cr6+ i = 15mg/L; CD = 14.36mA/cm2; pHi = 5.2; RSE = 73rpm. Compared to the Taguchi model, the BR-ANN model outperformed in terms of providing higher Cr6+ removal (+ 4.83%); reduced energy demand (-0.035 KWh/gm Cr6+ remove); lower error function value (χ2 = -7.9674 and RMSE = -3.5414); and highest R2 value (0.9991). The data for the conditions 91,007 < Re < 227,517 and Sc = 102.834 were found to fit the equation for the initial Cr6+ concentration of 15mg/l; Sh = 3.143Re0.125 Sc0.33. The Cr6+ removal kinetics was best described by Pseudo 2nd Order model, as validated by high R2 and lower error functions value. The SEM and XRF analysis confirmed that Cr6+ was adsorbed and precipitated along with metal hydroxide sludge. The rotating electrode led to lower SEEC (10.25 kWh/m3), as well as maximum Cr6+ removal (98.83%), compared to EC process with stationary electrodes.

Tracking Electrolyte Motion in Cylindrical Li-ion Cells Using Moment of Inertia Measurements

High energy density cylindrical Li-ion cells are densely packed with active materials, inactive materials and electrolyte. Injected electrolyte generally fills all pore spaces in the electrodes and separators of manufactured cells with possibly some excess. When such cells are charged, the overall volume of the electrode materials increases and therefore some electrolyte is pushed under hydraulic pressure to the spaces outside the electrode winding at the ends of the cylindrical can and also possibly into the hollow core of the cylindrical electrode winding. During discharge this electrolyte reenters the pore spaces of the electrodes as electrode particles contract. Therefore, the moment of inertia of the cell about an axis perpendicular to the axis of the cylindrical can change as the cell is charged and discharged. We have built a torsional oscillator that can measure the resonant frequency, and hence the moment of inertia, of a cylindrical Li-ion cell as it is charged and discharged. Because the moment of inertia of the cell depends on the electrolyte distribution, we can “watch” the electrolyte move within the cell. The design and operation of the instrument is described here as well as experiments that demonstrate the electrolyte motion that occurs in cylindrical cells. Consequences of this electrolyte motion are discussed.

New Generation Dielectrophoretic-Based Microfluidic Device for Multi-Type Cell Separation

This study introduces a new generation of dielectrophoretic-based microfluidic device for the precise separation of multiple particle/cell types. The device features two sets of 3D electrodes, namely cylindrical and sidewall electrodes. The main channel of the device terminates with three outlets: one in the middle for particles that sense negative dielectrophoresis force and two others at the right and left sides for particles that sense positive dielectrophoresis force. To evaluate the device performance, we used red blood cells (RBCs), T-cells, U937-MC cells, and Clostridium difficile bacteria as our test subjects. Our results demonstrate that the proposed microfluidic device could accurately separate bioparticles in two steps, with sidewall electrodes of 200 µm proving optimal for efficient separation. Applying different voltages for each separation step, we found that the device performed most effectively at 6 Vp-p applied to the 3D electrodes, and at 20 Vp-p and 11 Vp-p applied to the sidewall electrodes for separating RBCs from bacteria and T-cells from U937-MC cells, respectively. Notably, the device's maximum electric fields remained below the cell electroporation threshold, and we achieved a separation efficiency of 95.5% for multi-type particle separation. Our findings proved the device's capacity for separating multiple particle types with high accuracy, without limitation for particle variety.

Green Hydrogen Gas Production Using an Adapted Electrolysis Method

An electrolysis cell for hydrogen gas production was constructed in the form of a fixed bed. The electrodes were made from 316L stainless steel in the form of cylinders 15 mm in height and diameter (aspect ratio = 1). The electrodes were immersed in an aqueous solution of 1 M, 1.5 M, and 2 M sodium hydroxide. Both anodic and cathodic solutions were pumped from a 30-liters stainless steel storage tank by two plastic pumps. Flowrate was varied during the experiments between 1,2, and 3 liters/min. The cathodic and anodic compartments were separated by a cation exchange membrane (Fumasep E-620-K). The membrane is characterized by a non-reinforced, small thickness of 20µm, with very low resistance, high selectivity, and high stability in different pH environments. Using cylindrical electrodes allowed to maximize of the surface area on each side of the cell with the same NaOH concentration. The effect of current density was investigated by conducting experiments at, 4 mA/cm2, 6 mA/cm2, and 8 mA/cm2. The temperature was also varied (55 oC, 65 oC, and 75 oC) which resulted in an increase in the cell efficiency from 8.3% to 81.5%.

Flow-through charge detection mass spectrometry to categorize micron-sized particles.

This paper outlines the use of charge detection mass spectrometry to simultaneously measure the charge and mass of micron-sized particles. In a flow-through instrument, the detection of charge was achieved through charge induction onto cylindrical electrodes that connect to a differential amplifier. Mass was determined by particle acceleration under the influence of an electric field. Particles ranging from 30 to 400 fg (3 to 7 µm diameter) were tested. The detector design can measure particle mass within 10% accuracy for particles up to 620 fg with total charge ranging from 500e- to 56ke-. This charge and mass range are expected to be relevant for dust on Mars.

A Scheme for Correcting Temperature Errors in a Moisture Transducer Based on Cylindrical Electrodes

A Scheme for Correcting Temperature Errors in a Moisture Transducer Based on Cylindrical Electrodes

First thrust measurements in ionic multi-propeller rotational engines

Rotary ionic engines (RIEs) with multi-coaxial contra-rotating propellers (12.6 cm diameter) and their axial thrust are investigated in laboratory conditions, in air at atmospheric pressure, for the first time. The goal is to evaluate more advantageous configurations that may be scaled up and further help with development of rotary ionic drones. The propellers are designed with regular pin-emitter electrodes placed coaxially inside a cylindrical collector electrode. When high voltage is applied, propellers spin generating conventional axial thrust which is measured with an electronic scale in a “see-saw” setup. Up to 40 mN thrust was obtained in single propeller RIE at 2600 rpm, 0.34 mA, 37.5 kV, and an optimal collector electrode diameter of 17 cm. More thrust can be obtained with two and three propellers at constant current per propeller but at a decreased efficiency. Varying the axial propeller-separation showed that propeller-interaction is minimal above 5 cm. Thrust-to-power and thrust-to-current ratios were calculated and compared. We experimentally confirm here for the first time that within certain limits, the thrust-to-power variation can be assessed by the propeller kinetic energy-to-power ratio and also by the impedance of the gap (voltage-to-current ratio). A comparison of RIE arrays performance with one, two, and three coaxial propellers and the same total number of propellers per array (six) is also performed. RIE arrays with multi-coaxial propellers can provide larger thrust densities than single-propeller arrays. Also, arrays employing two coaxial propeller unit may be more weight effective.

Employment of cylindrical electrolytic copper grade electrode under EDMed Inconel 825 super alloy: emphasis on machining behavior accompanied with surface topography for sustainability

Employment of cylindrical electrolytic copper grade electrode under EDMed Inconel 825 super alloy: emphasis on machining behavior accompanied with surface topography for sustainability