Number Of Electrode Pairs Research Articles

Exploring charge regeneration effect in interdigitated array electrodes-based TENGs for a more than 100-fold enhanced power density

The vast potential of harnessing high entropy and abundantly available mechanical energy through triboelectric nanogenerators (TENGs) has attracted significant attention in recent years. However, the cost of harvesting this energy has often outweighed the energy collected. Recent advancements in TENGs for blue energy harvesting from water flow have shown great promise. In this study, we present a novel approach to optimize the performance of interdigitated electrode array-based TENGs operating in free-standing mode (IDA-FTENG) by introducing a gap-to-width ratio (GWR) relationship for the electrodes and its impact on the charge regeneration effects. We investigate the dependence of the charge regeneration effect on GWRs and the number of electrode pairs to enhance the performance of IDA-FTENGs, employing a rapid and industrially scalable laser scribing process for fabricating the devices. An optimized device, featuring a maximum of 34 interdigitated electrode grids, demonstrates a 140-fold increase in power density compared to conventional single electrode pair TENGs (SEP-TENGs). Furthermore, power density projections indicate that the optimized IDA-FTENGs can compete with current solar cells, if designed suitably. We showcase the applicability of the proposed IDA-FTENG devices in self-powered sensors, autonomous wireless operations, security monitoring, and smart home systems.

Effect of electrode configuration on minichannel heat sink with EHD vortex generators

A numerical study has been performed to understand the effects of electrode spacing on thermo-hydraulic performance in a minichannel assisted with electrohydrodynamics (EHD) based active vortex generation. A minichannel design with alternate high voltage and grounded electrodes flushed to the walls of the channel is considered. Multiple cases with different combinations of electrode length and spacing (pitch) at Reynolds number varying from 200 to 1000 are investigated. The numerical framework consisting of the two-way coupled governing equations for flow, thermal, charge, and electric potential fields is developed in the open-source finite-volume framework of OpenFOAM®. Applying an electric field induces the Onsager–Wien effect, producing flow vortices from electrode pairs. The EHD vortices disrupt the inherent laminar flow structure in the minichannel. The flow morphology is characterized by alternate vortex and shear dominant zones near the top and bottom walls. The EHD vortex dominant zones near the channel wall disrupt the laminar boundary layers. Thus, fluid mixing and heat transfer in the minichannel are enhanced. Electrode size and spacing influence the electric field distribution in the flow domain. As a result, electrode length and the inter-electrode spacing notably influenced the flow structure and the resulting heat transfer in the minichannel. The electrode spacing or the pitch decides the number of electrode pairs in the minichannel. An increase in pitch leads to fewer electrode pairs; thus, the electric field intensity is weak. Hence, EHD vortices in configurations with wider electrode spacing are weaker in strength. Longer electrodes produced stronger electric fields due to increased charge accumulation. Therefore, EHD vortices generated by longer electrodes are prominent and influential. The influence of EHD vortices on flow disruption and heat transfer is significant at lower Reynolds numbers. Cases with smaller electrodes perform well at higher Reynolds numbers, whereas usage of bigger electrodes exhibits higher performance at lower Reynolds numbers. Within the parameter space of this study, a minimum of 38.1% and a maximum of 60.6% enhancement in heat transfer is observed. A maximum performance factor of 1.46 is obtained in the present study using an electric current of 30μA with an electric power consumption of 30.1mW, which are notably low. Thus, the results of the present study exhibit that EHD vortex generation using the Onsager–Wien effect is a viable and economical option for thermo-hydraulic performance enhancement in a minichannel. Insights provided in the present study will be helpful to engineers and researchers in designing minichannel heat sinks with EHD-based performance improvement.

The High-Efficiency Design Method for Capacitive MEMS Accelerometer.

In this research, a high-efficiency design method of the capacitive MEMS accelerometer is proposed. As the MEMS accelerometer has high precision and a compact structure, much research has been carried out, which mainly focused on the structural design and materials selection. To overcome the inconvenience and inaccuracy of the traditional design method, an orthogonal design and the particle swarm optimization (PSO) algorithm are introduced to improve the design efficiency. The whole process includes a finite element method (FEM) simulation, high-efficiency design, and verification. Through the theoretical analysis, the working mechanism of capacitive MEMS accelerometer is clear. Based on the comparison among the sweep calculation results of these parameters in the FEM software, four representative structural parameters are selected for further study, and they are le, nf, lf and wPM, respectively. le and lf are the length of the sensing electrode and fixed electrode on the right. nf is the number of electrode pairs, and wPM is the width of the mass block. Then, in order to reduce computation, an orthogonal design is adopted and finally, 81 experimental groups are produced. Sensitivity SV and mass Ma are defined as evaluation parameters, and structural parameters of experimental groups are imported into the FEM software to obtain the corresponding calculation results. These simulation data are imported into neural networks with the PSO algorithm. For a comprehensively accurate examination, three cases are used to verify our design method, and every case endows the performance parameters with different weights and expected values. The corresponding structural parameters of each case are given out after 24 iterations. Finally, the maximum calculation errors of SV and Ma are 1.2941% and 0.1335%, respectively, proving the feasibility of the high-efficiency design method.

A vertically paired electrode for redox cycling and its application to immunoassays.

An electrochemical immunoassay based on the redox cycling method was presented using vertically paired electrodes (VPEs), which were fabricated using poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as an electrode material and parylene-C as a dielectric layer. For the application to immunoassays, different electrochemical properties of PEDOT:PSS were analyzed for the redox reaction of 3,3',5,5'-tetramethylbenzidine (TMB, the chromogenic substrate for enzyme-immunoassays) at different pH conditions, including the conductivity (σ), electron transfer rate constant (kapp), and double-layer capacitance (Cdl). The influencing factors on the sensitivity of redox cycling based on VPE based on PEDOT:PSS were analyzed for the redox reaction of TMB, such as the electrode gap and number of electrode pairs. Computer simulation was also performed for the redox cycling results based on VPEs, which had limitations in fabrication, such as VPEs with an electrode gap of less than 100 nm and more than five electrode pairs. Finally, the redox cycling based on VPE was applied to the medical diagnosis of human hepatitis-C virus (hHCV) using a commercial ELISA kit. The sensitivity of the redox cycling method for the medical diagnosis of hHCV was compared with conventional assay methods, such as TMB-based chromogenic detection, luminol-based chemiluminescence assay, and a rapid test kit (lateral flow immunoassay).

Numerical Analysis of Mixing Performance in an Electroosmotic Micromixer with Cosine Channel Walls.

Micromixers have significant potential in the field of chemical synthesis and biological pharmaceuticals, etc. In this study, the design and numerical simulations of a passive micromixer and a novel active electroosmotic micromixer by assembling electrode pairs were both presented with a cosine channel wall. The finite element method (FEM) coupled with Multiphysics modeling was used. To propose an efficient micromixer structure, firstly, different geometrical parameters such as amplitude-to-wavelength ratio (a/c) and mixing units (N) in the steady state without an electric field were investigated. This paper aims to seek a high-quality mixing solution. Therefore, based on the optimization of the above parameters of the passive micromixer, a new type of electroosmotic micromixer with an AC electric field was proposed. The results show that the vortices generated by electroosmosis can effectively induce fluid mixing. The effects of key parameters such as the Reynolds number, the number of electrode pairs, phase shift, voltage, and electrode frequency on the mixing performance were specifically discussed through numerical analysis. The mixing efficiency of the electroosmotic micromixer is quantitatively analyzed, which can be achieved at 96%. The proposed micromixer has a simple structure that can obtain a fast response and high mixing index.

Two-stage particle separation channel based on standing surface acoustic wave.

Microfluidic technology has great advantages in the precise manipulation of micro and nano particles, and the collection method of micro and nano particles based on ultrasonic standing waves has attracted much attention for its high efficiency and simplicity of structure. This article proposes a two-stage particle separation channel using ultrasound. In the microfluidic channel, two different sound pressure regions are used to achieve the separation of particles with positive acoustic contrast factors. Through numerical simulation, the performance of three common piezoelectric substrate materials was compared qualitatively and quantitatively, and it was found that the output sound pressure intensity of 128°YX-LiNbO3 was high and the output was stable. At the same time, the influence of the number of electrode pairs of the interdigital transducer and the electrode voltage on the output sound wave is studied. Finally, 15 pairs of electrode pairs are selected, and the electrode voltages of the two sound pressure regions are 2.0 V and 3.0 V, respectively. After selecting the corresponding parameters, the separation process was numerically simulated, and the separation of three kinds of particles was successfully achieved. This work has laid a certain theoretical foundation for rapid disease diagnosis and real-time monitoring of the environment in practical applications.

Capacitive biosensor based on vertically paired electrodes for the detection of SARS-CoV-2

Vertically paired electrodes (VPEs) with multiple electrode pairs were developed for the enhancement of capacitive measurements by optimizing the electrode gap and number of electrode pairs. The electrode was fabricated using a conductive polymer layer of PEDOT:PSS instead of Ag and Pt metal electrodes to increase the VPE fabrication yield because the PEDOT:PSS layer could be effectively etched using a reactive dry etching process. In this study, sensitivity enhancement was realized by decreasing the electrode gap and increasing the number of VPE electrode pairs. Such an increase in sensitivity according to the electrode gap and the number of electrode pairs was estimated using a model analyte for an immunoassay. Additionally, a computer simulation was performed using VPEs with different electrode gaps and numbers of VPE electrode pairs. Finally, VPEs with multiple electrode pairs were applied for SARS-CoV-2 nucleoprotein (NP) detection. The capacitive biosensor based on the VPE with immobilized anti-SARS-CoV-2 NP was applied for the specific detection of SARS-CoV-2 in viral cultures. Using viral cultures of SARS-CoV-2, SARS-CoV, MERS-CoV, and CoV-strain 229E, the limit of detection (LOD) was estimated to satisfy the cutoff value (dilution factor of 1/800) for the medical diagnosis of COVID-19, and the assay results from the capacitive biosensor were compared with commercial rapid kit based on a lateral flow immunoassay.

Mixing performance of an electroosmotic micromixer with Koch fractal structure

Abstract In this paper, we have designed a Koch fractal electroosmotic micromixer (KFEM). A low-voltage electroosmotic micromixer. In order to optimize the electrode position, Koch microchannel is designed according to the Koch fractal principle and the electrode pairs based on the fractal are arranged. Then the effect of electrode voltage, electrode distribution positions, the number of electrode pairs, two kinds of Koch fractal structures, Reynolds (Re) number and the frequency of alternating current (AC) on the mixing performance are studied. The results show that the mixing efficiency can reach 99% in a short time when the AC voltage is 1 V, the AC frequency is 12 Hz and the electroosmotic micromixer has two sets of electrode pairs.

Enhanced Performance of Spiral Co-planar Inter-Digital Capacitive Structures for Sensing Applications

In this work we consider a Spiral Inter-Digital Capacitive (SIDC) structure for its optimum design and performance analysis based on finite element simulation, for possible application as sensors. The effects of relevant geometrical parameters like sensor electrode width, inter-electrode gap, number of electrode pairs and electrode height on sensor output capacitance are evaluated and analyzed. In addition, influence of a test sample over the designed sensor for varying lift-off distances from the top of the sensor surface and for various material permittivity values are investigated. Results of the studies show that a spiral structure has about 25% higher sensitivity for its capacitance value compared to a corresponding Rectangular Inter-Digital Capacitive (RIDC) structure of comparable dimensions. The simulation results have been verified experimentally by fabricating and testing SIDC and RIDC structures for dielectric characterization of materials and proximity measurement applications. The results point to the possibility of designing and fabricating spiral inter-digital capacitive sensors with higher sensitivity for a multitude of applications.

Dielectrophoretic Microfluidic Device for Separating Microparticles Based on Size with Sub-Micron Resolution.

This article details the mathematical model of a microfluidic device aimed at separating any binary heterogeneous sample of microparticles into two homogeneous samples based on size with sub-micron resolution. The device consists of two sections, where the upstream section is dedicated to focusing of microparticles, while the downstream section is dedicated to separation of the focused stream of microparticles into two samples based on size. Each section has multiple planar electrodes of finite size protruding into the microchannel from the top and bottom of each sidewall; each top electrode aligns with a bottom electrode and they form a pair leading to multiple pairs of electrodes on each side. The focusing section subjects all microparticles to repulsive dielectrophoretic force, from each set of the electrodes, to focus them next to one of the sidewalls. This separation section pushes the big microparticles toward the interior, away from the wall, of the microchannel using repulsive dielectrophoretic force, while the small microparticles move unaffected to achieve the desired degree of separation. The operating frequency of the set of electrodes in the separation section is maintained equal to the cross-over frequency of the small microparticles. The working of the device is demonstrated by separating a heterogeneous mixture consisting of polystyrene microparticles of different size (radii of 2 and 2.25 μm) into two homogeneous samples. The mathematical model is used for parametric study, and the performance is quantified in terms of separation efficiency and separation purity; the parameters considered include applied electric voltages, electrode dimensions, outlet widths, number of electrodes, and volumetric flowrate. The separation efficiencies and separation purities for both microparticles are 100% for low volumetric flow rates, a large number of electrode pairs, large electrode dimensions, and high differences between voltages in both sections.

Effect of the Aperture of an Interdigital Transducer on the Characteristics of Its Output Signal in a Piezoelectric Plate

A study is made of the effect the aperture and the number of electrode pairs of an interdigital transducer (IDT) have on the characteristics of acoustic signals A1 and SH1 excited in a LiNbO3YX-plate. The obtained dependences of signal intensity on the experimental parameters demonstrate the possibility of miniaturizing integrated sensors consisting of a array of sensors based on delay lines or single IDT resonators.

Вплив числа електродних пар на похибку електрохімічного давача поляризаційного опору для вимірювання шидкості атмосферної корозії

Investigate the influence of the number of electrode pairs of multi-electrode co-surface electrochemical polarization resistance sensors on the error of measurement of polarization resistance, and, accordingly, on the corrosion rate under atmospheric conditions. Method of polarization resistance. Determination of the contact area of electrodes with the aluminum substrate by the method of obtaining a print on a flat surface. Graphical modeling of the contact surface of the sensing element from the steel electrodes to the anodized aluminum substrate. Investigation results of the influence of the electrode pairs number of multielectrode cosurface electrochemical polarization resistance sensor, sensing element of which is steel-made and is located on the thermoconductive anodized aluminum substrate, on the measurement error of corrosion rate in atmospheric conditions are presented. It was shown that in determining of the corrosion rate by polarization resistance method the increasing of the electrode pairs number of sensor from one to four increases the reproducibility of measurement results and their convergence with the gravimetric data. Taking into account the form of prints of four-pair sensitive element, the area of surface contact of sensitive element of eight-pair sensor with aluminum substrate was graphically simulated. It was taken into account during modeling, that the design feature of the sensor is a possibility of full contact of one pair of the electrodes with the substrate, which explains the reason of measurement error increasing with increasing the number of electrodes’ pairs. Increasing the pairs number from one to four and then to eight decreases the part of surface of sufficiently tight contact of sensitive element with aluminum substrate from 100% to 50% and further up to 30 %. The extreme dependence of the measurement error on the number of electrodes pairs due to the increasing area of the working surface of the electrodes and reducing the area of tight contact with the aluminum heat-conducting base was revealed. It was found that four electrodes pairs for the presented sensor design is optimal. It was established that the reason of increasing of the error of polarization resistance measurement under atmospheric conditions and, accordingly, the corrosion rate, by using the electrochemical multi-electrode co-surface sensors of polarization resistance under increasing the electrode pairs number (from one to eight) is the decreasing in the surface part of a sufficiently dense contact of the sensitive element (about two or three times). Another tendency that leads to decreasing in error is decreasing in the error of setting the corresponding polarization while increasing the total area of the electrodes. The extreme dependence of this error on the number of electrode pairs with a minimum for a four-pair sensor is shown. The problem of uncontrolled variation of the measurement error by using the polarization resistance sensor of the considered construction was solved and the optimal number of electrode pairs (four) was determined. Using such of a sensor will allow to evaluate the corrosivity of the atmospheric air environment with respect to the responsible metal structures and their corrosion state in local corrosion-dangerous places with stable and minimal error.

Thermodynamic profiling during irreversible electroporation in porcine liver and pancreas: a case study series

First, the aim of the study was to determine whether irreversible electroporation (IRE) is associated with heat generation in the liver and pancreas at clinical (≤1,500 V/cm) and supraclinical (>1,500 V/cm) electroporation settings; second, to assess the risk of thermal tissue damage in and adjacent to the treated volume in highly perfused versus moderately perfused parts of both organs; third, to investigate the influence of perfusion and of the presence and the orientation of a metal stent on the maximal thermal elevation (ΔTSession,max) in the tissue during an IRE session at fixed IRE settings, and finally, to determine whether the maximum temperature elevation within the IRE-subjected organ during an IRE treatment (single or multiple sessions) is reflected in the organ's surface temperature. The aims were investigated in 12 case studies conducted in five female Landrace pigs. Several IRE settings were applied for lateral (2), triangular (3), and rectangular (4) electrode configurations in the liver hilum, liver periphery, pancreas head, and pancreas tail. IRE series of 10-90 pulses were applied with pulse durations that varied from 70 μs to 90 μs and electric field strengths between 1,200 V/cm and 3,000 V/cm. In select cases, a metal stent was positioned in the bile duct at the level of the liver hilum. Temperatures were measured before, during, and after IRE in and adjacent to the treatment volumes using fiber optical temperature probes (temperature at the nucleation centers) and digital thermography (surface temperature). The occurrence of thermal damage was assumed to be at temperatures above 50 °C (ΔTSession,max ≥ 13 °C relative to body temperature of 37 °C). The temperature fluctuations at the organ surface (ΔTLocSurf) were compared to the maximum temperature elevation during an IRE treatment in the electroporation zone. In select cases, IRE was applied to tissue volumes encompassing the portal vein (PV) and a constricted and patent superior mesenteric vein (SMV) to determine the influence of the heatsink effect of PV and SMV on ΔTSession,max. The median baseline temperature was 31.6 °C-36.3 °C. ΔTSession,max ranged from -1.7 °C to 25.5 °C in moderately perfused parts of the liver and pancreas, and from 0.0 °C to 5.8 °C in highly perfused parts. The median ΔTLocSurf of the liver and pancreas was 1.0 °C and 10.3 °C, respectively. Constricting the SMV in the pancreas head yielded a 0.8 °C higher ΔTSession,max. The presence of a metal stent in the liver hilum resulted in a ΔTSession,max of 19.8 °C. Stents parallel to the electrodes caused a ΔTSession,max difference of 4.2 °C relative to the perpendicular orientation. Depending on IRE settings and tissue type, IRE is capable of inducing considerable heating in the liver and pancreas that is sufficient to cause thermal tissue damage. More significant temperature elevations are positively correlated with increasing number of electrode pairs, electric field strength, and pulse number. Temperature elevations can be further exacerbated by the presence and orientation of metal stents. Temperature elevations at the nucleation centers are not always reflected in the organ's surface temperature. Heat sink effects caused by large vessels were minimal in some instances, possibly due to reduced blood flow caused by anesthesia. Appropriate IRE settings must be chosen based on the tissue type and the presence of stents to avoid thermal damage in healthy peritumoral tissue and to protect anatomical structures [Table: see text].

Multichannel Nerve Stimulation for Diverse Activation of Finger Flexors.

Neuromuscular electrical stimulation (NMES) is a common approach to restore muscle strength of individuals with a neurological injury but restoring hand dexterity is still a challenge. This study sought to quantify the diversity of finger movements elicited by a multichannel nerve stimulation technique. A 2 × 8 stimulation grid, placed on the upper arm along the ulnar and median nerves, was used to activate different finger flexors by automatically switching between randomized bipolar electrodes. The forces from each individual finger as well as the high-density electromyogram (HDEMG) of the intrinsic and extrinsic flexors were recorded. The elicited finger forces were categorized using hierarchical clustering, and the 2D correlation of the spatial patterns of muscle activation was also calculated. A wide range of movement patterns were identified, including multi-finger and single-digit movements. Additionally, a number of electrode pairs elicited similar finger movements. The muscle activation patterns showed similar and distinct spatial patterns, signifying activation redundancy. These results revealed the diversity of elicitable finger movements and muscle activations. The system redundancy can be explored to compensate for system instability due to fatigue or electrode shift. The outcomes can also enable the development of an automatic calibration of the stimulation.

Model-Based Performance Study of Dielectrophoretic Flow Separator

This article presents model-based analysis of a dielectrophoretic microfluidic flow separator in terms of separation efficiency and purity. The device employs interdigitated transducer electrodes on the bottom surface, and they run over the entire width of the microchannel. The device realizes type-based separation, specifically electrical properties, by capturing one type of microscale entity on the electrode surface due to positive dielectrophoresis (DEP) while keeping the other type suspended in the medium due to negative DEP. The model describes the trajectory of microscale entities, electric field potential, and fluid velocity in the microchannel and accounts for forces related to DEP, sedimentation, drag, virtual mass, and inertia. The model is used for parametric study using polystyrene and silica microparticles with radius of 3 μ m; parameters analyzed are flowrate, applied electric potential, number of electrode pairs, and electrode/gap length. Separation efficiency of the levitated microscale entity is 100% for all input parameters, while that of the captured microscale entity varies. Separation purity of the captured microscale entity is 100% for all input parameters, as long as the other type remains levitated, while that of the levitated microscale entity varies. The model developed in this article can help select parameters for achieving the desired level of performance metrics. The model is validated using experimental data on levitation of latex microparticles for voltages of 1–8 Vpp in a microfluidic device with electrode/gap length of 20 μ m and height of 120 μ m. The novelty of the model is that it is dynamic and can model the simultaneous capture and levitation of microscale entities in the microfluidic device.

Design and numerical simulation of a novel microfluidic electroosmotic micromixer with three electrode pairs

AbstractBACKGROUNDMiniaturization of experimental instruments in the field of biochemistry and medicine has become more and more common. A major trend in microfluidic technology is the miniaturization of experimental instruments. The relatively simple design and fabrication of active micromixers has attracted more and more attention.RESULTSIn this paper, we design and simulate a novel electroosmotic micromixer that uses microelectrodes located in microchannel walls. The study first compares the mixing effect of the micromixer without and with electrodes, and then investigates the effects of the number of electrode pairs, the value of the alternating voltage and the AC frequency on the mixing performance.CONCLUSIONWhen the electroosmotic micromixer has three electrode pairs at alternating voltage of 10 V and alternating frequency of 16 Hz, the best mixing efficiency can reach 98.2%. We call this micromixer TEEM (three electrode electroosmotic micromixer). At the same flow velocity, the mixing efficiency of TEEM is 30% higher than the electrodeless micromixer. This paper provides an effective theoretical support for the design of active electroosmotic micromixers, and provides a potential application value for further research and manufacture of electroosmotic micromixers used in biomedicine. © 2019 Society of Chemical Industry

Microfluidic Schottky-junction photovoltaics with superior efficiency stimulated by plasmonic nanoparticles and streaming potential.

A droplet energy harvester (DEH) composed of aqueous salt solution could generate electrical energy from light when placed on a metal–semiconductor Schottky-junction emulating the principles of electrochemical photovoltaics (ECPV). The maximum potential difference generated was ∼95 mV under sun, which was enhanced by ∼1.5 times after the addition of gold nanoparticles (AuNPs) in the droplet because of the generation of additional charge carriers from the localized surface plasmon resonance (LSPR). Focusing the solar illumination through a bi-convex lens on five such droplets increased the voltage to ∼320 mV with a power density of ∼0.25 mW cm−2. When the DEH was converted to a microfluidic energy harvester (MEH) by flowing the AuNP laden salt solution through a microchannel integrated with an array of Schottky-junction electrodes, at an optimal flow rate, another two-fold increase in the power density was observed. In the MEH, because the ECPV aided by the LSPR converted the solar energy into electrical energy, the streaming potential (SP) generated across the electrodes because of the fluid flow converted the mechanical energy into electrical energy. Increase in the number of electrode pairs improved the voltage generation, which suggested that the MEH had potential for microscale-very-large-scale-integration (μ-VLSI). The combined effects of ECPV, LSPR, and SP in the MEH could show an efficiency ∼2.5%, which was one of the highest ones reported, for Schottky-junction energy harvesters. This study shows some simple and efficient pathways to harvest high-density electrical power using microchannels and droplets from the naturally abundant solar or hydroelectric (hydel) energy resources.

Numerical simulation of dielectrophoretic particle separation using slanted electrodes

This study presents the numerical simulation and optimization of a dielectrophoretic (DEP) bio-separation chip for isolating bioparticles such as circulating tumor cells. The chip consists of an array of slanted electrodes placed on the top and bottom walls of the channel with an angle of 5°, 10°, and 15° with respect to the flow direction. The spatially non-uniform electric field produced by the slanted electrodes applies a DEP force on the particles flowing through the channel. The repulsive DEP forces applied by the top and bottom electrode arrays are balanced in the normal direction (y), causing the particles to flow along the centerline of the channel. However, the lateral component (z) of the DEP force deflects particles in the lateral direction, guiding them toward different outlets based on their size. Numerical simulation of the particle-fluid transport was performed using OpenFOAM, an open-source computational fluid dynamics package. The computational model considers the dominant forces such as the DEP, hydrodynamic, and gravitational forces and simulates the deflection and trajectory of the particles within the microfluidic channel based on their size. Additionally, a parametric study was performed to investigate the effects of voltage, flow rate, number of electrode pairs, cell size, channel height, the angle of electrodes, and the width and spacing of electrodes on the separation process and to optimize the utility of the DEP devices for cell separation.

Scalable multi-electrode microbial electrolysis cells for high electric current and rapid organic removal

Microbial electrolysis cells (MECs) can be used to produce hydrogen gas from wastewater. A novel multi-electrode stack design was proposed and examined under various operating conditions to maximize electric current in MECs without precious metal catalysts. For the cathode in the electrode stack, stainless steel mesh generated higher electric current than activated carbon cloth. The electric current density increased in proportion to the number of electrode pairs as the maximum current density was 520 A m−3 in MEC-10 (10 electrode pairs), 270 A m−3 in MEC-5 (5 electrode pairs), and 45 A m−3 with a single electrode pair. The stacked MEC was not ideal for fed-batch operation due to the short inter-electrode distance (∼2 mm); consequently, continuous-recycle and -flow operation resulted in the high electric current generation. During continuous-flow operation, individual electrodes in MEC-10 and MEC-5 showed a variation in electric current capacity (0.9–2.7 mA for 0.6 mL min−1). The COD (chemical oxygen demand) removal rate increased from 45.7 to 128.8 mg-COD L−1 h−1 with increasing flow rate from 0.1 to 0.6 mL min−1. These findings indicate that the stacked multi-electrode design can magnify the current generation and COD removal rate in MECs.

Functional associations at global brain level during perception of an auditory illusion by applying maximal information coefficient

Maximal information coefficient (MIC) is a recently introduced information-theoretic measure of functional association with a promising potential of application to high dimensional complex data sets. Here, we applied MIC to reveal the nature of the functional associations between different brain regions during the perception of binaural beat (BB); BB is an auditory illusion occurring when two sinusoidal tones of slightly different frequency are presented separately to each ear and an illusory beat at the different frequency is perceived. We recorded sixty-four channels EEG from two groups of participants, musicians and non-musicians, during the presentation of BB, and systematically varied the frequency difference from 1 Hz to 48 Hz. Participants were also presented non-binuaral beat (NBB) stimuli, in which same frequencies were presented to both ears. Across groups, as compared to NBB, (i) BB conditions produced the most robust changes in the MIC values at the whole brain level when the frequency differences were in the classical alpha range (8–12 Hz), and (ii) the number of electrode pairs showing nonlinear associations decreased gradually with increasing frequency difference. Between groups, significant effects were found for BBs in the broad gamma frequency range (34–48 Hz), but such effects were not observed between groups during NBB. Altogether, these results revealed the nature of functional associations at the whole brain level during the binaural beat perception and demonstrated the usefulness of MIC in characterizing interregional neural dependencies.