Permeable Electrode Research Articles

Electrochemiluminescent evaluation of GLUT4 expression in rat adipocytes induced by Ganoderma lucidum polysaccharides

Glucose transporter 4 (GLUT4) directly facilitates cellular uptake of glucose and plays a crucial role in mammalian adipose tissue glucose metabolism. In this work, we constructed a cytosensor for sensitive electrochemiluminescence (ECL) detection of GLUT4 in rat adipocytes (RA cells). A carbon nanotube sponge (CNTSP) was selected to fabricate a permeable electrode to overcome the steric hindrance of cells on the electrode. The expression of GLUT4 after treatment with Ganoderma lucidum polysaccharide (GLP) was assessed by analyzing the luminescence emitted from cell-surface ECL probes. Our preliminary results suggest that GLP promote the expression of GLUT4, thereby enhancing the uptake of the fluorescent glucose 2-NBDG. Treatment with GLP affected GLUT4 expression in RA cells in a dose-dependent manner. Additionally, the ECL cytosensor contributes to the development of ECL imaging of receptors on the cell surface for clinical drug evaluation.

Gas permeable membrane electrode assembly with in situ utilization of authigenic acid and base for transmembrane electro-chemisorption to enhance ammonia recovery from wastewater

Ammonia recovery from wastewater is of great significance for aquatic ecology safety, human health and carbon emissions reduction. Electrochemical methods have gained increasing attention since the authigenic base and acid of electrochemical systems can be used as stripper and absorbent for transmembrane chemisorption of ammonia, respectively. However, the separation of electrodes and gas permeable membrane (GPM) significantly restricts the ammonia transfer-transformation process and the authigenic acid-base utilization. To break the restrictions, this study developed a gas permeable membrane electrode assembly (GPMEA), which innovatively integrated anode and cathode on each side of GPM through easy phase inversion of polyvinylidene fluoride binder, respectively. With the GPMEA assembled in a stacked transmembrane electro-chemisorption (sTMECS) system, in situ utilization of authigenic acid and base for transmembrane electro-chemisorption of ammonia was achieved to enhance the ammonia recovery from wastewater. At current density of 60 A/m2, the transmembrane ammonia flux of the GPMEA was 693.0 ± 15.0 g N/(m2·d), which was 86 % and 28 % higher than those of separate GPM and membrane cathode, respectively. The specific energy consumption of the GPMEA was 9.7∼16.1 kWh/kg N, which were about 50 % and 25 % lower than that of separate GPM and membrane cathode, respectively. Moreover, the application of GPMEA in the ammonia recovery from wastewater is easy to scale up in the sTMECS system. Accordingly, with the features of excellent performance, energy saving and easy scale-up, the GPMEA showed good prospects in electrochemical ammonia recovery from wastewater.

Recent Advances in Stretchable and Permeable Electrodes for Epidermal Electronics

AbstractEpidermal electronics is an emerging wearable platform that involves attaching deformable forms of devices to the skin. Epidermal electrodes represent a vital component of this technology, as they provide a direct electronic interface with the skin for sensing and stimulation. However, most of the current electrodes are built on non‐permeable elastomer substrates, which can limit their long‐term, continuous operations in a non‐invasive manner. Fortunately, recent advancements in conductive materials and fabrication techniques have enabled high‐performance epidermal electrodes that are comfortable to wear. In order to track the latest progress, this review article first introduces the designs of permeable structures and the preparation of conductive electrodes. The subsequent discussion elaborates on effective strategies to achieve desirable properties, such as high conductivity, stretchability, skin adhesion, and biocompatibility. The emerging applications of permeable epidermal electrodes are also summarized. Finally, this review concludes with the current challenges and future directions of breathable epidermal electrodes.

Subcutaneous mechano-electrocardiogram (MECG) sensor for complementary cardiac diagnosis

Since the heart pumps out the blood through the excitation-contraction coupling, simultaneous monitoring of the electrical and mechanical characteristics is beneficial for comprehensive diagnosis of cardiac disorders. Currently, these characteristics are monitored separately with electrocardiogram (ECG) and medical imaging techniques. This work presents a fully implantable device named mechano-electrocardiogram (MECG) sensor that can measure mechanocardiogram (MCG) and ECG together. The key to the success is fabrication of permeable electrodes on a single low-modulus porous nanofiber mat, which helps immediate adhesion of the sensor on the tissue. A strain-insensitive electrode is used as the ECG electrode and a strain-sensitive electrode is used for MCG. The MECG device is implanted subcutaneously in the skin above the heart of the rat. Through a vasopressor (phenylephrine) injection test, the MECG signals indicate that the MCG amplitude is related with blood pressure and the ECG peak interval is more related with heart rate. These results confirm that the MECG device is clinically meaningful for continuous and comprehensive monitoring of the electrical and mechanical characteristics of the heart.

Effect of Temperature and H Flux on the NH3 Synthesis via Electrochemical Hydrogen Permeation.

Ammonia is an indispensable commodity and a potential carbon free energy carrier. The use of H permeable electrodes to synthesize ammonia from N2 , water and electricity, provides a promising alternative to the fossil fuel based Haber-Bosch process. Here, H permeable Ni electrodes are investigated in the operating temperature range 25-120 °C, and varying the rate of electrochemical atomic hydrogen permeation. At 120 °C, a steady reaction is achieved for over 12 h with 10 times higher cumulative NH3 production and almost 40-fold increase in faradaic efficiency compared to room temperature experiments. NH3 is formed with a cell potential of 1.4 V, corresponding to a minimum electrical energy investment of 6.6 kWh kg-1 . The stable operation is attributed to a balanced control over the population of N, NHx and H species at the catalyst surface. These findings extend the understanding on the mechanisms involved in the nitrogen reduction reaction and may facilitate the development of an efficient green ammonia synthesis process.

A computationally‐cost effective model for fluid flow in redox flow batteries

AbstractRedox flow batteries (RFBs) hold great potential for large‐scale, extended‐duration stationary energy storage. Here, a novel computationally cost‐effective hydraulic‐electrical analogous model (HEAM) for fluid flow in RFBs is developed. The HEAM demonstrated that lowering the electrode compression and enhancing the channel area lowers the pump power loss independent of the flow fields and electrodes. Additionally, the HEAM helped elucidate the deficiencies of flow distribution in interdigitated flow fields (IFFs) and suggested designing wider manifolds and/or shorter channels improve the flow distribution. Moreover, the HEAM suggested shallower and/or wider channels, and more permeable electrodes enhance the flow penetration rate above the channels. Finally, the HEAM showed that the average penetration depth in the electrode above the ribs (hpen) was the critical parameter in the fluid‐flow modeling of IFFs and was inversely proportional to the permeability. Hence, there is a trade‐off between the pump power loss and hpen when configuring electrode permeability.

A gas permeable membrane electrode for selective and durable H2S production from SO2

Converting SO2 into H2S is of great importance in recovering sulfur from SO2 streams, and even across the sulfur chemistry. However, H2S will comproportionate with SO2, resulting in undesired sulfur deposition to impede SO2 reduction reaction. Herein, a new concept of electrolysis paradigm to produce H2S from SO2 was introduced, wherein a gas-permeable catalyst membrane (Au/PTFE) was designed to in situ synthesis and separate H2S from the electrolyte, avoiding sulfur deposition behavior. This catalyst membrane electrolysis demonstrates a good performance with H2S Faraday efficiency of 99.6 % and separation efficiency of 99.1 %, with superior operational stability (exhibiting 38-hours continuous electrolysis without sulfur deposition). Computational studies and spectroscopic results reveal that S0 is the key intermediate for H2S production from SO2. The in situ separation of H2S not only prevents the S0 formation but also helps to self-clean the catalyst surface.

In Situ Study of Hydrogen Permeable Electrodes for Electrolytic Ammonia Synthesis Using Near Ambient Pressure XPS.

Hydrogen permeable electrodes can be utilized for electrolytic ammonia synthesis from dinitrogen, water, and renewable electricity under ambient conditions, providing a promising route toward sustainable ammonia. The understanding of the interactions of adsorbing N and permeating H at the catalytic interface is a critical step toward the optimization of this NH3 synthesis process. In this study, we conducted a unique in situ near ambient pressure X-ray photoelectron spectroscopy experiment to investigate the solid-gas interface of a Ni hydrogen permeable electrode under conditions relevant for ammonia synthesis. Here, we show that the formation of a Ni oxide surface layer blocks the chemisorption of gaseous dinitrogen. However, the Ni 2p and O 1s XPS spectra reveal that electrochemically driven permeating atomic hydrogen effectively reduces the Ni surface at ambient temperature, while H2 does not. Nitrogen gas chemisorbs on the generated metallic sites, followed by hydrogenation via permeating H, as adsorbed N and NH3 are found on the Ni surface. Our findings suggest that the first hydrogenation step to NH and the NH3 desorption might be limiting under the operating conditions. The study was then extended to Fe and Ru surfaces. The formation of surface oxide and nitride species on iron blocks the H permeation and prevents the reaction to advance; while on ruthenium, the stronger Ru-N bond might favor the recombination of permeating hydrogen to H2 over the hydrogenation of adsorbed nitrogen. This work provides insightful results to aid the rational design of efficient electrolytic NH3 synthesis processes based on but not limited to hydrogen permeable electrodes.

Effects of a flexible ion gel as an active outer-layer when in contact with a metallic electrode

In this work, the effect of an ion gel outer-layer stuck on top of ITO/PBT/Sn devices was investigated towards its effects on the electrical properties. When this external electrolyte film is in contact with any top permeable electrode, it produces a self-biasing effect and changes the charge carriers’ injection properties. The outer-layer promoted situations where the output current increases up to two orders of magnitude and others where the output current decreases one order of magnitude in comparison to the same samples without it. Admittance spectroscopy measurements were made and the proposed equivalent circuit model indicates that the interfacial electrical properties dominate charge carrier injection face the bulk properties when the outer-layer is present. All the changes observed here are reversible after the ion gel is detached and replaced, indicating that ions do not diffuse into the active layer. The observed results can contribute to improve the current density in certain sandwich structures as well as notify that electrolyte external films can behave as an active layer promoting electrical changes into sandwich devices and can be extended to cases where the electrolyte film is used as substrate.

Modelling the fluid mechanics in single-flow batteries with an adjacent channel for improved reactant transport

Redox flow batteries (RFBs) are an emerging electrochemical technology envisioned towards storage of renewable energy. A promising sub-class of RFBs utilizes single-flow membraneless architectures in an effort to minimize system cost and complexity. To support multiple functions, including reactant separation and fast reactant transport to electrode surfaces, electrolyte flow must be carefully designed and optimized. In this work, we propose adding a secondary channel adjacent to a permeable battery electrode, solving for the flow field and analysing the effects on the reactant concentration boundary layer at the electrode. We find that an adjacent channel with gradually changing thickness leads to a desired nearly uniform flow through the electrode to the adjacent channel. Consequently, the thickness of the concentration boundary layer is significantly reduced, increasing reactant transport to the electrode surface to 140% of the rate of a battery with a constant width adjacent channel, and 350% of the rate with no adjacent channel. Overall, this theory provides insight into the important role of flow physics for this promising sub-class of flow batteries, and can pave the way to improved energy efficiency of such flow batteries.

Ammonia Synthesis at Ambient Conditions via Electrochemical Atomic Hydrogen Permeation.

Direct electrochemical nitrogen reduction holds the promise of enabling the production of carbon emission-free ammonia, which is an important intermediate in the fertilizer industry and a potential green energy carrier. Here we show a strategy for ambient condition ammonia synthesis using a hydrogen permeable nickel membrane/electrode that spatially separates the electrolyte and hydrogen reduction side from the dinitrogen activation and hydrogenation sites. Gaseous ammonia is produced catalytically in the absence of electrolyte via hydrogenation of adsorbed nitrogen by electrochemically permeating atomic hydrogen from water reduction. Dinitrogen activation at the polycrystalline nickel surface is confirmed with 15N2 isotope labeling experiments, and it is attributed to a Mars–van Krevelen mechanism enabled by the formation of N-vacancies upon hydrogenation of surface nitrides. We further show that gaseous hydrogen does not hydrogenate the adsorbed nitrogen, strengthening the benefit of having an atomic hydrogen permeable electrode. The proposed approach opens new directions toward green ammonia.

Determination of Partial Proton Conductivity in Fluorite-Type Oxides Using Electrochemical Technique

The oxide ion blocking measurements using Pd as hydrogen permeable electrode was conducted to detect proton conduction in 8YSZ. The blocking measurements with increasing applied voltage were firstly performed, but no significant deference was observed between the measured conductivities in dry and wet conditions. The reason was thought to be the decrease in p H2O at the blocking electrode caused by the application of high voltage, so the experimental conditions were modified. Under constant low applied voltage and p O2, the current response to switching from dry to wet atmosphere was recorded. Current increment by humidification and its protons/deuterons isotopic effect was observed, which means proton conduction in 8YSZ was successfully detected. The proton conductivity calculated from the current increment was 7.8×10−8 Scm−1 at 750°C.

In situ backside Raman spectroscopy of zinc oxide nanorods in an atmospheric‐pressure dielectric barrier discharge plasma

AbstractThis work presents in situ backside Raman spectroscopy as a method for the investigation of atmospheric‐pressure plasma modification of thin oxide films on metals. By using the backside of a permeable electrode, various contributions from the plasma (UV radiation, electrons, etc.) are blocked, which allows us to solely evaluate the effect of the plasma effluent. This approach is applied to study the influence of different gas mixtures (Ar, Ar/H2O, and Ar/O2) on the plasma treatment of zinc oxide nanorod films. The spectral analysis reveals the interaction of the plasma effluent with the zinc sublattice, introducing defects dependent on the plasma gas‐phase composition. The in situ measurements show that both the effluent/surface interaction and the resulting defects induce lattice stress in the wurtzite structure. Ex situ Raman measurements demonstrate that the defect stability over time depends on the defect type. The results for the dielectric barrier discharge plasma modification of ZnO‐nanostructured thin films indicate that the presented Raman spectroscopic setup is suitable for a variety of systems with a focus on remote plasma modifications.

Efficient and low-voltage vertical organic permeable base light-emitting transistors.

Organic light-emitting transistors, three-terminal devices combining a thin-film transistor with a light-emitting diode, have generated increasing interest in organic electronics. However, increasing their efficiency while keeping the operating voltage low still remains a key challenge. Here, we demonstrate organic permeable base light-emitting transistors; these three-terminal vertical optoelectronic devices operate at driving voltages below 5.0 V; emit in the red, green and blue ranges; and reach, respectively, peak external quantum efficiencies of 19.6%, 24.6% and 11.8%, current efficiencies of 20.6 cd A-1, 90.1 cd A-1 and 27.1 cd A-1 and maximum luminance values of 9,833 cd m-2, 12,513 cd m-2 and 4,753 cd m-2. Our simulations demonstrate that the nano-pore permeable base electrode located at the centre of the device, which forms a distinctive optical microcavity and regulates charge carrier injection and transport, is the key to the good performance obtained. Our work paves the way towards efficient and low-voltage organic light-emitting transistors, useful for power-efficient active matrix displays and solid-state lighting.

Direct synthesis of barium titanium oxyhydride for use as a hydrogen permeable electrode

Barium titanium oxyhydride BaTiO3−xHx with H−/e− mixed conductivity was directly synthesized by a mechanochemical method, and its function as a hydrogen permeable electrode was confirmed.

Development of Permeable and Transparent Intracranial Electrode Embedded in Hydrogel Substrate

In surgery of epilepsy, a patient's cranium is opened for intracranial electroencephalogram (iEEG) measurement or electrical stimulation to treat a part of a brain causing seizures [1]. Conventionally, intracranial metal electrodes with a silicone rubber substrate have been widely used in iEEG measurements during surgery. However, the substrate of the electrode is stiff and needs to be pressed down to fit on the surface of the brain, which increases the tissue damage during the insertion into in a deep sulcus called a longitudinal cerebral fissure or a Silvian fissure. Besides, the low transparency of the electrode substrate decreases the immediate recognition of the diseased area, and the lack of permeability of that also cause damage to the brain in long term treatment including an implantation of the electrode. Herein, a flexible intracranial electrode using a hydrogel as a substrate was developed [2]. A soft carbon fabric electrode was embedded in a hydrogel composed of poly (vinyl alcohol) (PVA). The PVA hydrogel has excellent flexibility, biocompatibility, water content, and hydrophilicity, which leads to well adhesion and conformability to the brain. Moreover, the transparency of PVA hydrogel is expected to improve the visibility of the brain under the substrate and its permeability ensure adequate fluid delivery.Carbon fabric electrodes were fabricated by cutting the electrodes and lead wires out of the fabric and applying an insulation coating. The non-insulated electrode surface was coated with conductive particle polymer poly (3,4-ethylenedioxythiophene) (PEDOT) to increase the surface area and increase the electrical capacity. This process is to prevent electrolysis from occurring during electrical stimulation[3]. A gel precursor solution was prepared by dissolving PVA in distilled water and adding dimethyl sulfoxide (DMSO). The electrodes were embedded in the precursor solution and gelated by repeated freezing and thawing cycles. DMSO provided an uniform and clear gel, and to avoid its irritation, the obtained gel was soaked and washed well in saline.Figures 1 shows the electrodes placed on the brain model. While the conventional electrodes with silicone substrate hardly followed the shape of the object (Figure 1a), the electrodes with hydrogel substrate followed the object well (Figure 1b). The object was not clear to observe through the conventional silicone substrate, and that substrate did not swell the water droplet placed on the surface (Figure 1c). In contrast, the hydrogel-based substrate was clear after the adhesion onto the brain model, and the water droplets placed on the surface were spread over the entire surface and adsorbed to the hydrogel-based substrate. These results indicated that electrodes with a hydrogel substrate could adhere well to the brain surface while minimizing damage to the tissue, and allowing observation of the affected area during surgery.Our developed electrode with soft, hydrophilic, and soft hydrogel substrate were promising device for the treatment of epilepsy, overcoming the conventional problems and leading to new medical approach.

Fabrication and electrical characterization of vertical electrolyte transistor

Here, it is reported a vertical electrolyte transistor (VET) whose structure is based on stacked layers: bottom contact → channel → permeable intermediate electrode → ion gel (electrolyte gate dielectric) → gate top contact. This VET depicts versatility to work with two different mode of operation, as: Electrolyte-Gated Vertical Organic Field Effect Transistor (Electrolyte-Gated VOFET) or Vertical Organic Electrochemical Transistor (VOECT). The difference is regarding to the transistor transconductance that occurs due to induced charge carriers or ionic current, respectively. Here, the focus is on giving special attention to the electrical characterization of the VET diode cell in comparison to the VET full architecture. These measurements are able to provide the baseline output current from a VET and consequently distinguish it from possibles different modes of operation created by ionic species. Both modes of operation show that this VET is able to work at very low voltage range and drive a high current density.

Ion Wind in a Three-Electrode Surface Barrier Discharge Arrangement

An experimental study of the velocity field in a three-electrode arrangement of a plasma-chemical surface dielectric barrier discharge (SDBD) reactor designed for plant seed’s treatment was carried out. The effect of polarity and magnitude of the extraction voltage (potential of the third electrode), configuration of the SDBD system (5- and 10-mm distances between the strips were observed) and the permeability for gas flow of the third electrode (in the form of a plate or a grid) on the magnitude of the extraction ion current, and induced gas flow structure were analyzed. It is shown that the most uniform flow in the direction of the third electrode, necessary for uniform seed treatment, is achieved in the case of a permeable third electrode under positive displacement potential, opposing a surface discharge electrodes with a distance between the strips much less than the gap dimensions (5 mm between the strips with 10 mm between the third electrode and the barrier surface).

An analytical model of glow discharge positive column in axially symmetric channel with variable cross section

A model of glow discharge positive column in gas flow is considered in this paper. It is supposed the discharge is between the permeable mesh electrodes installed in the initial and end sections of axially symmetric channel. In general case the channel width changing along the stream is accounted. The positive column in gas flow is described by integro-differential system of equations with an approximation of constant gas flow density. The border conditions for gas ionization degree and temperature in the initial section of channel are given by any functions. An analytical solution of that system was obtained. The special cases of the boundary conditions are analyzed.

Design, Synthesis, and Characterization of a Water–Stable Li+ ion-Conducting Sulfonate-Based Neutral Metal-Organic Framework

The desire for ion permeable electrode separators in rechargeable batteries has led to an increase in interest in lithium ion-conducting metal-organic frameworks (MOFs). A novel, water-stable, 2D sheet-like neutral Cu (I) −sulfonate MOF, could be the first example of significant lithium ion-conductivity in a neutral, practically solvent-free, not post-synthetically modified MOF. The naphthalenediimide (NDI) ligands of this MOF are capable of simultaneously binding guest lithium ions to its carbonyls and uncoordinated sulfonate oxygen atoms, while charge diffuse perchlorate anions coordinate through anion−π interaction. When made into pristine MOF pellets, the intrinsic electrical conductivity was rather poor (4.65x10−10 S/m) at room temperature. This was due to deficient electron delocalization pathways and charge carrier density. Yet, upon the insertion of LiClO4, the ionic conductivity grew by a factor of 106 to 2.3x10−4 S/m and the activation energy for the charge carrier transport to 0.167 eV. To show the impact of the Li+ binding, the MOF was treated with Bu4NClO4, and the conductivity was essentially unchanged from the original value. The lack of conductivity can be attributed to the size exclusion and facile removal of large uncoordinated Bu4N+ cations. Thus, this presents a new strategy to develop ion-conducting sulfonate MOFs for potential battery applications