Mesh Electrode Research Articles

Development of a scalable electrochemical filter for removing nitrate from recirculating aquaculture saltwater

Electrochemical technology is promising for the selective removal of nitrate from recirculating aquaculture saltwater. For commonly used sequential batch or flowing by reactor, the electrostatic repulsion of electric double layer near cathodic surface to NO3‾ anions brings essential adsorption limit, which suppresses the efficiency of NO3‾ reduction. In order to solve this problem, an electrochemical filter was created by installing mesh electrodes with regulated thickness. During saltwater flowing through the filter, NO3‾ have to flow through cathodic holes with diameter of one and half hundred micrometers. Compared with centimeter-scale electrode gap of commonly used reactors, this micrometer-scale diffusion distance increases the concentration gradient, which intensifies NO3‾ diffusion to the cathode surface and counteracts electrostatic repulsion. In line with expectations, for 50.0 mg/L of initial nitrate-N, nitrate-N in effluent of this filter was only 2.0 mg/L, no ammonia-N and nitrite-N were detected, which met Chinese standard of water quality for aquatic mammals in aquariums (SC/T 9411-2012). While for batch process and flow-by process, the effluent concentration of nitrate-N was 60.6% and 47.6% higher than that of flow-through process, respectively. In addition, the filter displayed low energy consumption and wide availability for real recirculating aquaculture saltwater, RO wastewater and metallurgical wastewater. Furthermore, a scale-up reactor was assembled by connecting seventeen filters in series. Its water treatment capacity (5 L/h) exceeded most reported data. These results support the practicability of this novel electrochemical filter in denitrification from saltwater.

Improvement in discharge characteristics and energy yield of ozone generation via configuration optimization of a coaxial dielectric barrier discharge reactor

Dielectric barrier discharge (DBD) has been widely employed in ozone generation. However, the technology still exhibits relatively low energy yield (EY) referring to its theoretical value. In this work, EY of ozone generation was improved by optimizing the mesh number, electrode length, and dielectric material in a coaxial DBD reactor with two wire mesh electrodes. Meanwhile, the discharge characteristics were investigated to elucidate the effect of reactor configuration on EY. Results showed that the discharge characteristics were improved by increasing the mesh number, electrode length, and relative permittivity. When the mesh number was increased from 40 to 100, an improvement of approximately 48% in EY was obtained. Additionally, higher EY values were obtained using corundum as the dielectric material relative to polytetrafluoroethylene and quartz. Ultimately, EY in the optimal DBD reactor could reach 326.77 g·(kW·h)−1. Compared with the reported DBD reactor, the coaxial DBD reactor with the mesh electrode and the dielectric material of corundum could effectively improve EY, which lays a foundation for the design of high-efficiency coaxial DBD reactor.

A plano-convex thick-lens velocity map imaging apparatus for direct, high resolution 3D momentum measurements of photoelectrons with ion time-of-flight coincidence.

Since their inception, velocity map imaging (VMI) techniques have received continued interest in their expansion from 2D to 3D momentum measurements through either reconstructive or direct methods. Recently, much work has been devoted to the latter of these by relating electron time-of-flight (TOF) to the third momentum component. The challenge is having a timing resolution sufficient to resolve the structure in the narrow (<10ns) electron TOF spread. Here, we build upon the work in VMI lens design and 3D VMI measurement by using a plano-convex thick-lens (PCTL) VMI in conjunction with an event-driven camera (TPX3CAM) providing TOF information for high resolution 3D electron momentum measurements. We perform simulations to show that, with the addition of a mesh electrode to the thick-lens geometry, the resulting plano-convex electrostatic field extends the detectable electron cutoff energy range while retaining the high resolution. This design also extends the electron TOF range, allowing for a better momentum resolution along this axis. We experimentally demonstrate these capabilities by examining above-threshold ionization in xenon, where the apparatus is shown to collect electrons of energy up to ∼7eV with a TOF spread of ∼30ns, both of which are improved compared to a previous work by factors of ∼1.4 and ∼3.75, respectively. Finally, the PCTL-VMI is equipped with a coincident ion TOF spectrometer, which is shown to effectively extract unique 3D momentum distributions for different ionic species in a gas mixture. These techniques have the potential to lend themselves to more advanced measurements involving systems where the electron momentum distributions possess non-trivial symmetries.

Switchable Polyacrylonitrile-Copolymer for Melt-Processing and Thermal Carbonization-3D Printing of Carbon Supercapacitor Electrodes with High Capacitance.

Polyacrylonitrile (PAN) represents the most widely used precursor for carbon fibers and carbon materials. Carbon materials stand out with their high mechanical performance, but they also show excellent electrical conductivity and high surface area. These properties render carbon materials suitable as electrode material for fuel cells, batteries, and supercapacitors. However, PAN has to be processed from solution before being thermally converted to carbon, limiting its final format to fibers, films, and non-wovens. Here, a PAN-copolymer with an intrinsic plasticizer is presented to reduce the melting temperature and avoid undesired entering of the thermal carbonization regime. This plasticizer enables melt extrusion-based additive manufacturing (EAM). The plasticizer in the PAN-copolymer can be switched to increase the melting temperature after processing, allowing the 3D-melt-printed workpiece to be thermally carbonized after EAM. Melt-processing of the PAN copolymer extends the freedom-in-design of carbon materials to mold-free rapid prototyping, in the absence of solvents, which enables more economic and sustainable manufacturing processes. As an example for the capability of this material system, open meshed carbon electrodes are printed for supercapacitors that are metal- and binder-free with an optimized thickness of 1.5mm and a capacitance of up to 387 mF cm-2 .

Methyl orange degradation and hydrogen production simultaneously by a reverse electrodialysis−electrocoagulation coupling system powered by salinity gradient energy

To produce hydrogen and treat dye wastewater simultaneously, a salinity gradient energy (SGE) driven reverse electrodialysis（RED）− electrocoagulation (EC) coupling system was designed and investigated experimentally. Energy conversion was achieved by means of the ionic electromigration (across the membranes) and redox reaction (on the electrodes). The iron anode electrode was electro-dissolved and releases Fe2+ (to be oxidized to Fe3+), and OH– was produced at cathode electrode, which were combined to be the flocculent. Additionally, hydrogen was produced at the cathode. Experiments were conducted to investigate the effects of electrodes (surface, material, and structure) and concentration gradients (from 10:1 to 250:1) on dye methyl orange (MO) degradation and hydrogen production. It results that the use of iron electrode as anode is significantly more efficient than the aluminum electrode for MO degradation, but inversely for hydrogen production; as for cathodes, the largest MO degradation rate and hydrogen production are achieved by means of the titanium mesh electrode and titanium plate electrode respectively. When the working current is constant at 0.25 A, the MO degradation rate and hydrogen production are both decreased with the increase of the concentration gradient. When the experiments are carried under the short-circuit current condition, the MO degradation rate reaches 98.1 % in 70 min at the concentration gradient of 50:1, and the maximum hydrogen production is 294.15 ml·h−1 at the concentration gradient of 25:1. Besides, the evolutions of the following parameters have been observed, including the current of RED stacks, pH of solution, and dissolution of electrodes.

Semi-solid electrolyte with layered heterometallic low-valent electron-mediator enabling indirect destruction of gaseous toluene

The electrochemical degradation of air pollutants, particularly volatile organic compounds (VOCs), at their gaseous state is a promising method. However, it remains at an infant stage due to sluggish solid–gas electron transfers at room temperature. We established a triphase reaction condition using a semi-solid electrolyte layer between the electrode and membrane to enhance the electron transfer at room temperature. A polyvinyl alcohol (PVA) gel layer was inserted between a bimetallic layered CuNi(CN)4 complex coated Cu foam electrode (TCNi-Cu) and Nafion 324 membrane for the degradation of gaseous toluene. The cyclic voltammetry of TCNi-Cu using a sodium hydroxide-coated copper mesh electrode at a triphase showed Cu1+ and Ni1+ stabilization at −0.7 and −0.9 V, respectively, which was similar to the liquid phase electron transfer behavior. The degradation capacity of gaseous toluene without using electrogenerated TCNi-Cu + PVA gel was 0.54 mg cm2 min−1, whereas that of TCNi-Cu + PVA gel layers was 1.17 mg cm−2min−1, which revealed the mediation effect at a triphase condition. Toluene was converted into oxygen-containing products, such as butanol, propanol, and acetone (without reduction products), which revealed that indirect oxidation occurred at the cathode using an in-situ generated oxidant, such as OH˙ radical. As an electron-mediator, Cu1+ was used to form oxidants for the degradation of toluene at −0.7 V. The toluene removal rate reached 1.4 μmol h−1, with an energy efficiency of 0.15 Wh L−1. This study is the first attempt to describe a liquid-electrolyte-free cathodic half-cell in electrochemical application to VOCs degradation, highlighting the electron transfer at room temperature.

Charge sensitive preamplifier design optimization for low-pressure Micro-Megas gaseous detector operations

Using a bulk Micro-Megas (MM) detector an energy measurement can be obtained collecting the total charge reaching the mesh electrode connected to a low noise charge sensitive preamplifier. When operating such a device in a low-pressure gas regime, it is necessary to modify the amplification gap geometry to reach the optimal detector gain. This implies changes in the input capacitance of the preamplifier influencing its signal to noise ratio and thus the detector energy resolution. An ad-hoc high-gain and low-noise charge preamplifier has been developed to cope with the requirements of our application field. In this short report, we present the development activities focused to the study of a configurable charge amplifier to be connected to a MM detector having different mesh capacitances.

Morphology regulation and application of nano cobalt oxide (Co3O4) electrocatalysts for chlorine evolution toward marine anti-biofouling

For the optical equipment used in the marine environment, the quality and accuracy of the tests are easily affected by biological fouling. Hence, good anti-fouling performance is crucial for preserving the optical equipment. A new electrochemical chlorination anti-fouling system has been proposed for years and is suitable for underwater optical windows. In this paper, nano Co3O4 electrocatalysts with different morphologies were prepared through the hydrothermal method to study the structure-activity relationship between their electrochemical properties and morphologies. The nanourchin Co3O4 shows the best electrochemical properties resulting from its large surface area. The titanium mesh electrode with nanourchin Co3O4 was used to evaluate the anti-fouling performance. In comparison to commercial dimensionally stable anode electrodes, the developed Co3O4/titanium mesh electrode has higher catalytic performance, better selectivity, and lower cost. The bactericidal rate can reach 95% in 20 mins and it can effectively inhibit the sedimentation of microorganisms on the glass surface. Therefore, it is a promising strategy to use the nanourchin Co3O4 as an electrocatalyst to protect the underwater optical windows.

Effect of electrode parameters in the electro-production of reactive oxidizing species via boron-doped diamond under batch mode.

Ozone and hydroxyl radicals (• OH) are powerful reactive oxidizing species (ROS) that are commonly utilized in water disinfection. The electrochemical advanced oxidation process (EAOP) is often used to generate such oxidants, whereas optimizing its experimental setup and electrode parameters plays a crucial role in its performance. This research aims to find the optimal setup for ROS generation process from tap water via the boron-doped diamond. The effect of electrode's active area, type of electrode substrates (mesh or sheet), type of mesh substrate (rolled and unrolled), and number of anodes and cathodes are examined. The results showed that the use of two long-rolled BDD/Nb meshes as anode and one long-rolled mesh as a cathode gives the optimal performance of electrolysis process at 15 V potential and 3min. These results will provide a start for developing a cost accepted, health-safe, household disinfection device that reduces susceptibility to human life-threatening waterborne diseases. PRACTITIONER POINTS: This research aims to find the optimal setup for ROS generation process from tap water via the boron-doped diamond. The effect of electrode's parameters on the electro-production of ROS is examined. The best performance is achieved using rolled mesh electrodes. Two long-rolled BDD/Nb meshes as anode electrodes and one long-rolled mesh cathode electrode give the optimal electrolysis process performance.

Sinusoidal stretchable fibrous electrodes regulate cardiac contraction

The flexible electronics allowing regulate the performance of engineered cardiac tissue represents a promising approach for the treatment of cardiac diseases. However, the conventional electronic system is usually limited by mismatched biomechanical properties. Herein, exploring the natural flow behavior of the polymer melt in Melt electrowriting (MEW) under its non-linear printing phase, a fibrous mesh electrode with a sinusoidal anisotropic structure resembling the collagen fiber architecture in the heart was straightforwardly created. The structure-defined, biomimetic anisotropic viscoelastic behavior, withstanding thousands of cyclical and constant stretching, together with the fine-tuned anisotropic electrical properties, were employed at the electrode-cell interface for synchronizing cardiomyocytes beating. The anisotropic fibrous mesh electrode, which is 100 times thinner than human hair, easily conforms to the heart’s anisotropic structure to introduce bioelectrical stimulation to the surface of the diseased tissue evenly across a wide area. Electrical stimulation through the electrodes could modulate HL-1 murine cardiomyocyte contraction frequency. Meanwhile, human iPSC derived cardiomyocytes (iPSC-CMs) with well-developed sarcomeres and cellular electrical coupling were aligned and elongated along the stretchable electrode, which accommodated their in-plane contractions along the short axis, suggesting the good mechanical conformability to the heart beating. The stretchable electrode demonstrated in vivo biocompatibility by histology analysis. Overall, our anisotropic, stretchable electrode mesh holds great potential for cardiac repair.

Work-function-tunable metal-oxide mesh electrode and novel soluble bipolar host for high-performance solution-processed flexible TADF-OLED

Substantial effort has been dedicated to the development of solution-processed flexible organic light-emitting diodes (sf-OLEDs). However, to simultaneously enhance device performance and ensure stable operation under severe mechanical deformation, highly flexible transparent electrodes and efficient soluble organic emitting materials must be optimized together. Here, highly efficient green-emitting thermally activated delayed fluorescence (TADF) sf-OLEDs were developed using a mesh-structured Ni-doped indium zinc oxide (mNIZO) flexible electrode and a novel soluble bipolar host. The mNIZO electrode had excellent optical, electrical, and mechanical properties. The work function of the mNIZO electrode was engineered through surface doping with Ni without optical and electrical losses. 5-(9 H-Carbazol-9-yl)− 3′-(3,6-di-tert-butyl-9 H-carbazol-9-yl)-[1,1′-biphenyl]− 3-carbonitrile (CzCN-tCz) was synthesized as a soluble host material by incorporating a tert-butyl group into 3,3′-di(carbazol-9-yl)− 5-cyano-1,1′-biphenyl (mCBP-CN). Consequently, the mNIZO-based TADF sf-OLED with CzCN-tCz had a maximum external quantum efficiency of 21.0 % on a poly(ethylene 2,6-naphthalate) substrate, and 82 % of the initial luminance was maintained under severe mechanical stress, which is attributable to the high deformability of the mNIZO electrode. The proposed framework is expected to facilitate the design of high-performance cost-effective flexible displays with various forms through a simple process.

Electrocatalyst for oxygen evolution reaction and methanol oxidation using surface-oriented stable NiSnO3 nanospheres anchored g-C3N4 nanosheets

Transition metal oxides have arisen as smart and inexpensive electrocatalytic materials for water oxidation. In this work, a simple hydrothermal method is demonstrated for the first time to synthesize perovskite-type NiSnO3 nanospheres interacted with graphitic carbon nitride (g-C3N4) nanosheets with fruit-beared cherry tree like morphology and investigate its surface-oriented electrocatalytic performance such as oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). First, the structural and morphological analysis of the as-synthesized nanohybrid has been studied using various physico-chemical techniques to confirm the bonding interaction between NiSnO3 nanospheres and g-C3N4. For comparison, NiO, SnO2, and NiO/SnO2 nanocomposites were also synthesized and studied. This study highlights the surface-derived synergistic interaction between g-C3N4 nanosheets and NiSnO3 nanospheres, which have absolutely led the prepared NiSnO3/g-C3N4 nanohybrid loaded on 316 stainless steel (SSL) mesh electrodes to excellent electrocatalytic performances, assessed using linear sweep voltammetry (LSV), cyclic voltammetry (CV), and impedance analysis. The nanohybrid loaded electrode needs a low overpotential of 240 mV to reach the current density of 10 mA cm−2 and a Tafel slope of 42 mV dec-1 for OER. In addition, the synthesized nanohybrid loaded electrode was tested for methanol oxidation, which shows an enhanced electrocatalytic performance with a current density of 295 mA cm−2. The produced nanohybrid electrode also demonstrates long-term stability for both OER and MOR, suggesting as an alternate to noble metal electrocatalyst.

A comprehensive study on scaling up ethylene abatement via intermittent plasma-catalytic discharge process in a novel reactor configuration comprising multiple honeycomb monoliths

Dilute ethylene (C2H4) was removed in a novel plasma reactor comprising multiple honeycomb monoliths consisting of up to four PdO/ZSM-5/monolith catalysts. These monoliths were packed in a tubular reactor separated by mesh electrodes alternatively grounded or connected to a high voltage (HV) power source. The effect of the number of monoliths on the discharge power, adsorption, and removal of C2H4 was investigated. Additionally, the influence of the energy input, C2H4 inlet concentration, and gas flow rate on the C2H4 abatement was examined. The adsorption capacity, C2H4 conversion, and energy efficiency were observed to increase as the number of monoliths increased. The effect of the palladium (Pd) loading technique, namely ion exchange (IE), incipient wetness impregnation (IM), and combined IE-IM, IE followed by IM, on the C2H4 adsorption was also studied. The combined IE-IM method presented an exceptional adsorption capacity of ∼136 µmol/gcatalyst under humid conditions despite nonpolar nature of C2H4. C2H4 removal was performed via both continuous and cycled storage-discharge (CSD) plasma-catalytic oxidation processes. The CSD process was conducted in two ways: with intermittent C2H4 feed (CSD-IEF) and with maintained C2H4 feed (CSD-MEF), both comprising intermittent plasma discharge. Intriguingly, the performance of the CSD-MEF process was superior (56 J/L, 1.61 g/kWh) to that of the CSD-IEF (119 J/L, 0.98 g/kWh), and continuous process (∼228 J/L, 0.53 g/kWh) in terms of energy efficiency as well as the overall simplicity of the system.

Design and simulation of non-uniform electric field using mesh electrodes for electrorheological micro valves

The refresh rate of two-dimensional tactile information for visual impaired people using electrorheological (ER) technology is directly related to the flow rate of an ER valve. The bigger the flow rate is, the faster the tactile information is refreshed. For a parallel electrodes ER valve configuration, due to the limitation of Braille standard to the width of ER valve, the gap of flow channel which is also the gap of parallel electrodes is the only adjustable parameter to benefit the flow rate and at same time enhance operating voltages which contribute a big part of costs to a two-dimensional tactile information display system. A new mesh electrodes configuration is introduced to decouple the flow rate from the gap of electrodes while the flow cross section is determined by parameters of mesh electrodes. A quantity of effective electric field strength of an ER interaction space unit is used to evaluate the anisotropy electric field governed by mesh electrodes. The influences of geometrical parameters of mesh electrodes and applied voltages on the effective electric field strength were analyzed by using COMSOL Multiphysics. The simulation results show that the effective electric field strength increases with applied voltages and wire diameters, and decreases with electrodes gap and mesh clearances. These results provide fundamental laws for designing an ER micro valve governed by non-uniform electric field to some ER applications.

Nano MnOx encapsulated pyrrole-carbazole copolymer and polyvinyl chloride/carbon-coated flexible electrodes for solid-state supercapacitor cell

Pyrrole (Py) and carbazole (Cz) monomers are polymerized simultaneously in the presence of MnOx nanoparticles synthesized chemically on a stainless steel mesh (SSM) electrode by the pulse galvanostatic method in an acetonitrile medium. The resulting p(Py-co-Cz)/MnOx composite is characterized by cyclic voltammetry EIS, GCD XPS, XRD, FESEM, BET, and TEM. Since the current is applied for short periods in the presence of both monomers, p(Py-co-Cz) copolymer chains occur in short lengths, suitable for supercapacitor electrodes. The copolymer has higher Cm and lower Rct values as well as higher porosity that improves ion transport, thus greater stability than the homopolymers. It may be due to tricyclic Cz segments located between Py segments in the chains, which inhibit degradation. During the synthesis, nano-sized MnOx is also encapsulated homogeneously into the p(Py-co-Cz) coating, where 5 % is the weight percentage of manganese. Since the composite combines the advantages of the conductive polymer and metal oxide, it has the lowest Rct and highest Cm values among the coatings here. The p(Py-co-Cz)/MnOx coating with 10 mg cm−2 exhibits a high specific capacitance of 352 F g−1 at 5 A g−1 as well as flexibility, as its specific capacitance remains nearly stable (99 %) up to a bending angle of 90°. The cathode prepared from polyvinyl chloride (PVC)/activated carbon/carbon black on SSM operates within a wide voltage range of 0 to −1.5 V at 98 % cycle stability after 1000 cycles. The asymmetric cell configuration with the flexible anode and cathode electrodes provides 38 kW kg−1 and 5.28 Wh kg−1 at 5 A g−1 at a wide potential range of 2.1 V in PVA/Na2SO4 gel electrolyte, and the cycling stability was 67 % after 1000 cycles.

Spatially modulated femtosecond laser direct ablation-based preparation of ultra-flexible multifunctional copper mesh electrodes and its application.

Multifunctional electrodes possess superior properties such as high photoelectric properties and high stability. Laser manufacturing process is one of the widely used method for electrode fabrication. However, the current multifunctional electrode laser manufacturing process suffers from low fabrication speed. Here, we report a high-efficiency laser digital patterning process to fabricate copper-based flexible transparent conducting electrodes. By using a spatially modulated, one single laser spot is modulated into an array of spots with equal intensity, and the fabrication speed can be improved by more than 20 times over the traditional single pulse processing. In addition, copper mesh electrodes with a high photoelectric property have been fabricated. A transparent touch screen panel and multifunctional windows are fabricated with transparent electrodes to demonstrate their use in vehicle defogging, portable heating, and wearable devices.

Electrode Layout Optimization and Numerical Simulation of Cast Conductive Asphalt Concrete Steel Bridge Deck Pavement.

In order to obtain the optimal electrode layout and ice melting effect of cast conductive asphalt concrete steel bridge deck pavement, firstly, pouring conductive asphalt concrete was prepared; secondly, different electrode materials and layout methods were selected to test the heating rate of the specimen from start to 120 min, and the electrode materials and layout methods were optimized. Then, the finite element analysis software ANSYS was used to build the model for heating and ice melting simulation, and the indoor test was used to further verify the ice melting effect of the cast conductive asphalt coagulation with or without the insulation layer. Finally, the thermal-structural coupling analysis of cast conductive asphalt concrete steel bridge deck pavement was carried out using ANSYS finite element software. The results showed that the stainless steel electrode material had the best heating effect, and the electrode thickness in the range of 0.1~3mm had no effect on the heating effect. The intermediate heating rate of the upper surface of the stainless steel sheet electrode cast conductive asphalt concrete in the left and right external electrodes was 8 °C/h, while the intermediate heating rate of the upper surface of the stainless steel mesh electrode cast conductive asphalt concrete was 12.9 °C/h. The layout of the left and right buried stainless steel metal mesh was able to effectively improve the snow melting efficiency; ANSYS finite element ice melting simulation was used to obtain the variation law of ice melting efficiency and a temperature field of cast conductive asphalt concrete. The indoor ice melting test showed that when melting the same thickness ice layer at 50 V voltage, it took 240 min with an insulation layer and 720 min without an insulation layer, which was three times that of the ice with an insulation layer, which further verifies the superiority of its ice melting effect. The most unfavorable load position of pavement under load and temperature field was determined. The maximum tensile stress and compressive stress of the pavement surface were transverse, and the maximum shear stress of the pavement bottom was transverse.

Internal Mass Transport Induced Voltage Losses during Water Electrolysis on Interconnected Nickel Nanowire Mesh Electrodes

Nickel nanowire mesh electrodes offer great potential for water electrolysis in alkaline environment, given their high internal surface area, mechanical strength, and alkaline resistance. Here we use a nickel nanowire mesh with a specific area of 26 m2/cm3, resulting in ~100-fold area enhancement for a 4µm thick nanowire mesh, compared to planar nickel. This highly benefits geometric current density, potentially into a regime where mass transport is the main limiting factor. Therefore, we performed a systematic study of electrode behaviour under various mass transport conditions to decouple kinetic and mass transfer related contributions to electrode voltage losses.An electrochemical flow cell was designed to measure the nanowire mesh electrode performance under optimal mass transport conditions. The cell provided electrolyte flow through the nanomesh, enabling convective supply of reagent into the nanopores as well as convective removal of reaction products. Facilitated by the inherent strength of the nanowire mesh, superficial flow velocities up to 1 cm/s could be obtained, with which geometric current densities as high as 320 mA/cm2 could be measured in the kinetically limited (flowrate independent) regime.Internal mass transport limitations were isolated by use of an inverted rotating disk electrode (iRDE). Koutecky-Levich analysis was performed to compensate for external mass transfer contributions on both nanowire mesh electrodes and planar electrodes. The nanowire mesh as iRDE resembles operating conditions in an electrolyzer, whereas the planar electrode provides a well-defined benchmark area for the electrode surface activity.For both the oxygen evolution reaction as the hydrogen evolution reaction, mass transport limitations were studies as function of current density and electrolyte (NaOH) concentration. Nanowire mesh electrode operation in the presence of internal mass transport limitations was compared to the non-limited condition and planar benchmark, from which the electrode effectiveness factor could be calculated. A 1-d simplified model of the electrode was used to explain the observed phenomena and to provide guidance for design optimization.

Stretchable mesh microelectronics for the biointegration and stimulation of human neural organoids

Advances in tridimensional (3D) culture approaches have led to the generation of organoids that recapitulate cellular and physiological features of domains of the human nervous system. Although microelectrodes have been developed for long-term electrophysiological interfaces with neural tissue, studies of long-term interfaces between microelectrodes and free-floating organoids remain limited. In this study, we report a stretchable, soft mesh electrode system that establishes an intimate in vitro electrical interface with human neurons in 3D organoids. Our mesh is constructed with poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) based electrically conductive hydrogel electrode arrays and elastomeric poly(styrene-ethylene-butylene-styrene) (SEBS) as the substrate and encapsulation materials. This mesh electrode can maintain a stable electrochemical impedance in buffer solution under 50% compressive and 50% tensile strain. We have successfully cultured pluripotent stem cell-derived human cortical organoids (hCO) on this polymeric mesh for more than 3 months and demonstrated that organoids readily integrate with the mesh. Using simultaneous stimulation and calcium imaging, we show that electrical stimulation through the mesh can elicit intensity-dependent calcium signals comparable to stimulation from a bipolar stereotrode. This platform may serve as a tool for monitoring and modulating the electrical activity of in vitro models of neuropsychiatric diseases.

Influence of wire mesh electrodes on the volume and surface characteristics of dielectric barrier discharge of atmospheric pressure helium

The dielectric barrier discharge of helium in a 6 mm gap at atmospheric pressure was studied. In this paper, the influence of electric field distribution on the uniformity of DBD is analyzed theoretically and verified by experiments. The experimental results show that the mesh electrode produces a local enhancement effect by affecting the electric field and then produces corona discharge, which provides seed electrons for the subsequent discharge process. The effects of mesh diameter and size on discharge uniformity and stability are analyzed, the electrode structure parameters are optimized, the method of a segmented electrode is proposed, and the discharge process and charge distribution are studied. The electrical diagnosis results of plasma technology show that the segmented mesh electrode reduces the breakdown voltage of DBD and increases the charge deposition.