Discrete Electrodes Research Articles

Electro-induced biochar-embedded-SIPN hydrogel as discrete bipolar electrodes for selective oxidation and enrichment of trace thallium(Ι)

Electrochemical techniques for thallium (Tl) treatment face a substantial challenge linked to the concentration of Tl(I), hindering the efficient removal and recovery of trace Tl(I) (μg L−1). In response, we synthesized hydrogel particles incorporating biochar (BC) within semi-interpenetrating polymer networks (SIPN), showcasing robust selectivity for Tl(I). These biochar-embedded-SIPN hydrogel particles (BC-SIPN particles), employed as dispersed electrodes, facilitated the targeted oxidation and enrichment of Tl(I) through electro-induction. Research outcomes elucidate the adept mitigation of the “efficiency-dependent concentration” behavior by electro-induced BC-SIPN particles during the reaction process. Under optimized conditions (pH 12, 2 V cm−1, 30 min), Tl(I) removal efficiency surpassed 98 % at an initial concentration of 100 μg L−1. The SIPN structure enhanced particle stability, and after seven cycles of enrichment in a 100 μg L−1 Tl(I) environment, BC-SIPN particles achieved a Tl content of 0.073 %, meeting Tl mineral content standards and promoting the recovery of scarce Tl resources. First-principles calculations underscore the pivotal role of hydrogen bond-electrostatic interactions between TlOH(aq) and particles in driving selective Tl(I) adsorption. Insights from quenching and capture reactions reveal a predominant direct oxidation pathway of Tl(I) to Tl(Ⅲ), complemented by indirect oxidation driven by reactive oxygen species, including OH, O- 2 and 1O2. This study presents an innovative approach for trace Tl(I) wastewater treatment, simultaneously mitigating the “efficiency-dependent concentration” phenomenon, and underscores the transformative potential of electro-induced BC-SIPN hydrogel particles in offering sustainable solutions for Tl(I) removal and resource recovery in environmental stewardship.

A novel discrete linkage-type electrode for radiofrequency-induced intestinal anastomosis

Introduction For decades, radiofrequency (RF)-induced tissue fusion has garnered great attention due to its potential to replace sutures and staples for anastomosis of tissue reconstruction. However, the complexities of achieving high bonding strength and reducing excessive thermal damage present substantial limitations of existing fusion devices. Materials and methods This study proposed a discrete linkage-type electrode to carry out ex vivo RF-induced intestinal anastomosis experiments. The anastomotic strength was examined by burst pressure and shear strength test. The degree of thermal damage was monitored through an infrared thermal imager. And the anastomotic stoma fused by the electrode was further investigated through histopathological and ultrastructural observation. Results The burst pressure and shear strength of anastomotic tissue can reach 62.2 ± 3.08 mmHg and 8.73 ± 1.11N, respectively, when the pressure, power and duration are 995 kPa, 160 W and 13 s, and the thermal damage can be controlled within limits. Histopathological and ultrastructural observation indicate that an intact and fully fused stomas with collagenic crosslink can be formed. Conclusion The discrete linkage-type electrode presents favorable efficiency and security in RF-induced tissue fusion, and these results are informative to the design of electrosurgical medical devices with controllable pressure and energy delivery.

Three-phase electrowetting liquid lens with deformable liquid iris.

Inspired by the arrangement of iris and crystalline lens in human eyes, we propose a three-phase electrowetting liquid lens with a deformable liquid iris (TELL-DLI). The proposed electrowetting liquid lens has three-phase fluid: air, conductive liquid, and dyed insulating liquid. The insulating liquid is distributed on the inner wall of the chamber in a ring shape. By applying voltage, the contact angle is changed, so that the dyed insulating liquid contracts towards the center, which is similar to the contraction of iris and the function of crystalline lens muscle in human eyes. The variation range of focal length is from -451.9 mm to -107.9 mm. The variation range of the aperture is from 4.89 mm to 0.6 mm. Under the step voltage of 200 V, the TELL-DLI can be switched between the maximum aperture state and the zero aperture state, and the switching time is ∼150/200 ms. Because of the discrete electrodes, TELL-DLI can regionally control the shape and position of the iris, and switch between circle, ellipse, sector, and strip. The TELL-DLI has a wide application prospect in imaging systems, such as microscopic imaging system, and has the potential to be applied in the field of complex beam navigation.

Multi-layering of carbon conductivity enhancers for boosting rapid recharging performance of high mass loading lithium ion battery electrodes

The ability of lithium ion batteries (LIBs) to provide rapid charging characteristics while retaining a substantial energy storage capacity is of paramount significance for their applicability in portable smart electronic devices. In this research, an effective approach to enhance re-charging rates of LIB cells was developed through incorporating carbon nanotube (CNT) conductivity boosters strategically into Li4Ti5O12 (LTO) electrodes. A layer-by-layer spray coating was exploited to manufacture multi-layer architectures that comprise sequential, discrete electrode layers of CNT-rich LTO and CNT-free LTO, aiming at promoting charge transfer kinetics of high mass loading electrodes. Initially, the optimal proportion of a CNT-rich layer and its best location within multi-layer electrode structures were investigated in half-cell configurations. The best performing multi-layer was then paired with a spray-coated LiFePO4 (LFP) positive electrode in full-cell LIBs, offering attractive power performance of ∼ 1500 W/kg that outperformed conventional LTO || LFP combinations.

Multi-channel electrical discharge machining of titanium alloy Ti-6Al-4V with semiconductor electrodes

Titanium alloys are extensively used in aerospace and medical engineering owing to their exceptional mechanical properties and biocompatibility. For a long time, the low thermal conductivity of titanium alloys has made them difficult to machine with conventional approaches. Electrical discharge machining (EDM) is a nonconventional method for machining difficult-to-cut materials. However, it is not possible to achieve high-quality surface finish while simultaneously maintain high machining efficiency. This paper introduced a new EDM approach to obtain high surface quality in machining titanium alloy Ti-6Al-4V with discrete semiconductor electrodes by utilising a new multi-channel discharge principle to disperse the discharge energy. To explore the dissimilarities in discharge characteristics between semiconductor electrodes and traditional copper electrodes, continuous discharge waveforms of both electrodes were compared. Through modelling the discharge equivalent circuit and analysing workpiece surface using scanning electron microscopy (SEM), it was discovered that, due to the unique electrical properties of the semiconductor, it is possible for semiconductor electrodes to form multiple discharge channels. The outcomes reveal that the utilization of semiconductor electrodes can disperse discharge energy and enhance surface quality without sacrificing material removal rate compared to the use of conventional copper electrodes.

Effective Thermoelectric Switch of Hollow Weakly-Coupled Molecular Junction Based on Twist Angle Effect with Boron-Doping

ABSTRACT Rational design and adjustment of flexible thermoelectric devices are key points for sustainable and effective thermoelectric conversion, which remains a fundamental challenge due to inherent high thermal conductivity and uncontrolled carrier concentration induced by non-uniform dispersion. Under ingenious combination of weakly-coupled hollow interface and nanotube structure, thermoelectric performance of a dumbbell-like molecular junction comprised of a phenyl-terminated polyyne as central molecule and two semi-infinite 1D single-walled carbon nanotube (SWCNT) as electrodes has been investigated at certain twisted angles (θ). The results indicate that molecule twisting can be reviewed as an effective thermoelectric switch to coordinatingly control electronic and phononic transmission properties simultaneously. Resonance of molecular discrete state and electrode continuous state leads to low thermal conductance, which is sensitively affected by twist angle. Meanwhile, cyclic transformation between p-type and n-type flexible thermoelectrics can be realized by manipulating twist angle in a certain period of rotation. Thermoelectric performance of such a molecular junction can be further improved by boron atom doping at head-to-tail positions, and an excellent figure of merit (ZT = 1.75) is observed near Fermi level under 25° twisted angle. This result inspires an effective strategy to modulate and control thermoelectric conversion, which will greatly broaden applications in thermoelectric twistronics.

The Role of Experimental Noise in a Hybrid Classical-Molecular Computer to Solve Combinatorial Optimization Problems.

Chemical and molecular-based computers may be promising alternatives to modern silicon-based computers. In particular, hybrid systems, where tasks are split between a chemical medium and traditional silicon components, may provide access and demonstration of chemical advantages such as scalability, low power dissipation, and genuine randomness. This work describes the development of a hybrid classical-molecular computer (HCMC) featuring an electrochemical reaction on top of an array of discrete electrodes with a fluorescent readout. The chemical medium, optical readout, and electrode interface combined with a classical computer generate a feedback loop to solve several canonical optimization problems in computer science such as number partitioning and prime factorization. Importantly, the HCMC makes constructive use of experimental noise in the optical readout, a milestone for molecular systems, to solve these optimization problems, as opposed to in silico random number generation. Specifically, we show calculations stranded in local minima can consistently converge on a global minimum in the presence of experimental noise. Scalability of the hybrid computer is demonstrated by expanding the number of variables from 4 to 7, increasing the number of possible solutions by 1 order of magnitude. This work provides a stepping stone to fully molecular approaches to solving complex computational problems using chemistry.

Multiplex Sensing Electronic Skin Based on Seamless Fully Printed Stretchable Piezoelectric Devices

AbstractWearable skin mountable devices, more than flexibility, require conformability, stretchability, and a high water vapor transmission rate, so that the perspiration processes are not blocked, to assure comfort and stability of use in contact with living bodies. Skin mountable stretchable devices with piezoelectric devices have been reported, based on the integration of polyvinylidene fluoride foils with discrete electrodes and stretchable substrates, and show potential in revolutionizing medical devices for remote monitoring applications. However, the electrodes and active layer are usually not stretchable, only the carrier substrate. The study reports the full description of a novel fully printed stretchable piezoelectric device, printed directly over a stretchable polymer foil of thermoplastic polyurethane. The stability of the response of the stretchable piezoelectric devices is used as movement sensors through their output potential. An electronic skin based on a fully printed circuit with a matrix of 15 all‐printed piezoelectric devices is prepared and investigated and used directly mounted on different body parts, and the real‐time monitoring of movements are recorded and analyzed.

Core-shell 2D/2D FeCo2O4@Ni(OH)2 nano-on-microsheet array architecture for excellent asymmetric supercapacitor performance

Core-shell designed electrode architectures with favorable material components are a promising approach to enhance electrochemical performance. Herein, binder-free 2D/2D FeCo2O4@Ni(OH)2 core–shell architectures were successfully grown on a Ni-foam (NF) substrate, where the FeCo2O4 microsheets were hydrothermally processed following the electro-grafting of Ni(OH)2 nanosheets as a “shell” around a FeCo2O4 “core.” These core–shell array architectures were utilized as a discrete electrode system; they exhibited a high specific capacitance of 1944 F g−1 at a current density of 5 A g−1, which is better than the performance of individual FeCo2O4 and Ni(OH)2. This improved performance was attributed to the synergistic effects of the robust core–shell array architectures developed over the NF substrate as well as the enhanced electrical conductivity through electroactive sites at the interface while maintaining the structural integrity of the Ni(OH)2 shell. In addition, the two-electrode device was assembled constituting a FeCo2O4@Ni(OH)2 ΙΙ activated carbon asymmetric supercapacitor, resulting in a maximum energy density of 136 W h kg−1 and power density of 8500 W kg−1, with 78% capacitance retention and 93% coulombic efficiency over 5000 cycles at a current density of 8 A g−1. These results validate the effectiveness of this approach for improving the performance of energy storage devices.

Mechanism of Thrust–Power Ratio Improvement Using Plasma Actuator with Discretized Encapsulated Electrodes

Plasma actuators (PA) can be utilized as fluid control devices without moving parts, but further improvement in drive efficiency is necessary. Herein, string-type PAs with up to 12 insulated conductive wires were evaluated to replace sheet-type PAs having a single encapsulated electrode. The thrust–power ratio of string-type PAs with eight or more wires is nine times that of a single-wire PA. This is due to the substantial increase in the width of the encapsulated electrode and the discrete arrangement of conductors in the streamwise direction. To determine the factors influencing the performance of PAs with discrete encapsulated electrodes, sheet-type PAs with and without discretized encapsulated electrodes and with the same configuration as string-type PAs were characterized. The measurement results revealed that no significant difference exists in the plasma extension length (LDBD) between sheet-type PAs without and with discretization under the same applied voltage, but 25% and 45% decreases in the thrust and power consumption, respectively, were observed compared to those of string-type PAs. The discretization of the encapsulated electrodes in the sheet-type plasma actuator increased the thrust–power ratio by 30%. Efficient non-mechanical fluid control using dielectric barrier discharge is therefore possible with string-type PAs with discrete electrodes.

Electro-Induced Carbon Nanotube Discrete Electrodes for Sustainable Persulfate Activation.

In electrochemical advanced oxidation processes (EAOPs), the rate-limiting step is the mass transfer of pollutants to the electrodes due to the limited active surface areas. To this end, we established a three-dimensional (3D) EAOP system by coupling conventional graphite electrodes with dispersed carbon nanotubes (CNTs). The electrodes (particularly the anode) induced electric field spontaneously polarized CNTs into dispersed reactive particle electrodes (CNT-PEs) in the solution, which remarkably promoted electrochemical activation of peroxydisulfate (PDS) to generate surface CNT-PDS* complexes and surface-bound radicals (SBRs). Based on the excited potential (ECNT-PEs) at different positions in the 3D electric field, CNT-PEs were activated into three states. (i) ECNT-PEs < Eorganic, CNT-PEs are chemically inert toward DCP oxidation; (ii) Eorganic < ECNT-PEs < Ewater, CNT-PEs will oxidize DCP via an electron-transfer process (ETP); (iii) ECNT-PEs > Ewater, both CNT-PDS* complexes and the anode will oxidize water to produce SBRs. Thus, DCP could be oxidized by CNT-PDS* complexes via ETP to form polychlorophenols on the CNT surface, causing rapid deactivation of the micro-electrodes. In contrast, SBRs attack DCP directly into chloride ions and hydroxylated products, maintaining the surface cleanliness and activity of CNT-PEs for long-term operations.

Efficacy of microconfined fluid mixing in a combined electroosmotic and pressure driven transport of complex fluid over discrete electrodes

This paper numerically investigates the mixing characteristics of an Oldroyd-B fluid flowing through a micro-channel having discrete electrodes along its walls driven by both electroosmotic force and pressure gradient. We consider both symmetric and asymmetric potential distributions along the wall while also probing the influence of fluid rheology and other physicochemical parameters of the problem. We report an improvement in mixing efficiency by increasing the relative strength of electroosmotic forcing and pressure gradient. It is also observed that the localized mixing efficiency decreases with an increase in surface potential. Fluid rheology changes the position of maximum efficiency depending on fluid properties without affecting mixing efficiency substantially. Compared with a continuous distribution, the five-electrode arrangement produces approximately equivalent mixing efficiency. We observe an increase in mixing efficiency at the micro-channel outlet as the gap between the electrodes increases. We have also analyzed the mixing characteristics for asymmetric charge distributions and illustrated the parameters controlling the flow dynamics. The results of the present study may prove helpful for the complete design and analysis of an active micromixer for the efficient transport of bio/polymeric fluids inside micro-channels.

A Radio-Frequency Time-of-Flight Ion Mass Analyzer with a Small Distance between Planar Discrete Electrodes

A Radio-Frequency Time-of-Flight Ion Mass Analyzer with a Small Distance between Planar Discrete Electrodes

Polarity dependent epicranial direct current stimulation over the cerebellum suppresses Harmaline tremor in rats

Abstract Background: Essential tremor (ET) is a neurological movement disorder that manifest a tremor in different body parts, but mainly the hands, leading to movement disability and social withdrawal. It is the most prevalent movement disorder with more than half of the patients not achieving satisfactory tremor reduction using medication. Thus, deep brain stimulation (DBS) becomes a standard treatment. However, DBS is highly invasive with stimulation electrodes being implanted in deep brain regions. To overcome that, the motor and the cerebellar cortex have been suggested as an alternative, more superficial, targets for stimulation. While results from an epidural cortical stimulation study were promising, this technique remains highly invasive requiring a craniotomy to implant the electrodes. Recently, we proposed a novel minimally invasive neuromodulation technique, epicranial current stimulation (ECS), that can deliver strong cortical current through subcutaneous electrodes. Here, we used Harmaline ET model in rats to test the ability of direct current epicranial current stimulation (DC-ECT) in reducing tremor. Methods: Rats were implanted with discrete epicranial electrodes placed over the motor cortices, the cerebellum and the frontal cortex. After surgery recovery, the rats were injected with Harmaline (15 mg/kg) to induce tremor which was measured using an accelerometer. Then DC-ECT was applied and different electrodes configurations were used to test the effects of stimulation on tremor suppression. Results: Our results show that DC-ECT suppresses Harmaline tremor in rats. Cerebellar stimulation showed a significant decrease in tremor compared to no stimulation. This effect was polarity dependent with anodal stimulation showing tremor reduction but not cathodal one. Conclusion: DC-ECT is a very promising neuromodulation technique that can suppress harmaline induced tremor in rats. Given its minimally invasive nature, it could be an alternative to DBS for ET patients. Keywords: epicranial stimulation, Essential tremor, Harmaline, Direct current stimulation

P‐16.12: Development of High Performance In‐cell Touch Panel based on Oxide TFT

In‐cell touch panel based on oxide TFT possesses excellent display performance, high SNR and supports LPWG function with lowest power consumption. However, due to the discrete electrode VCOM and low leakage current characteristics of oxide TFT, it is easy to cause static electricity and charge residual. In view of above problems, this paper fully introduces the product design and process of targeted optimization.

(Invited) Lithium-Ion Battery Direct Recycling Through Effective Electrochemical Intercalation

The Nobel Prize winning technology lithium-ion battery (LIB) has seen an annual market growth rate of 24% over the last decade. This rapid market expansion brings a huge amount of hazardous battery waste from end-of-life (EOL) disposal and creates concerns over the long-term sustainability of critical elements for producing batteries. There is an urgent need to develop effective battery recycling infrastructure to address these challenges. The incumbent indirect pyrometallurgical and hydrometallurgical recycling methods lead to high energy consumption and process cost, water contamination and low-value elemental products. [1,2] In contrast, direct recycling process that extract and restore high-value cathode materials (2-10 times more valuable than their corresponding elemental constituents depending on the chemistries used [3]) to their virgin composition, structure, morphology and electrochemical performance with minimal energy and environmental impact. We have developed disassembly automation and materials regeneration processes for direct recycling of LIBs. [4,5] The pouch cell with discrete electrode sheets separated via continuous z-folding separator dominates the design of the commercially available LIBs and is used here to introduce our direct disassembly process. The customized automatic disassembly machinery safely dismantles the cell pouch, separating anode and cathode sheets, and sort cell components (i.e., cathode sheets, anode sheets and separators) into different waste streams. The EOL cathode materials are retrieved and separated for relithiation via an effective electrochemical intercalation method. The dried cathode materials are then heat-treated after which the regenerated cathode materials exhibit physical properties and electrochemical performance is comparable to virgin commercial materials.[5][1] L. Gaines, K. Richa, J. Spangenberger, Key issues for Li-ion battery recycling, MRS Energy Sustain. 5 (2018). https://doi.org/10.1557/mre.2018.13.[2] G. Harper, R. Sommerville, E. Kendrick, L. Driscoll, P. Slater, R. Stolkin, A. Walton, P. Christensen, O. Heidrich, S. Lambert, A. Abbott, K. Ryder, L. Gaines, P. Anderson, Recycling lithium-ion batteries from electric vehicles, Nature. 575 (2019) 75–86. https://doi.org/10.1038/s41586-019-1682-5.[3] J.B. Dunn, L. Gaines, J.C. Kelly, K.G. Gallagher, Life Cycle Analysis Summary for Automotive Lithiumion Battery Production and Recycling, in: R.E. Kirchain, B. Blanpain, C. Meskers, E. Olivetti, D. Apelian, J. Howarter, A. Kvithyld, B. Mishra, N.R. Neelameggham, J. Spangenberger (Eds.), Rewas 2016 Mater. Resour. Sustain., John Wiley & Sons, Inc., 2016: pp. 73–79. https://doi.org/10.1002/9781119275039.ch11.[4] L. Li, P. Zheng, T. Yang, R. Sturges, M.W. Ellis, Z. Li, Disassembly Automation for Recycling End-of-Life Lithium-Ion Pouch Cells, JOM. 71 (2019) 4457–4464. https://doi.org/10.1007/s11837-019-03778-0.[5] T. Yang, Y. Lu, L. Li, D. Ge, H. Yang, W. Leng, H. Zhou, X. Han, N. Schmidt, M. Ellis, Z. Li, An Effective Relithiation Process for Recycling Lithium-Ion Battery Cathode Materials, Adv. Sustain. Syst. n/a (n.d.) 1900088. https://doi.org/10.1002/adsu.201900088.

Dynamic Electrical Pathway Tuning in Neuromorphic Nanowire Networks

AbstractNeurobiology‐inspired phenomena such as winner‐takes‐all competition and critical dynamics have been recently reported to arise in neuromorphic nanowire networks. These are unique systems where interactions between memristive elements creates emergent conductance pathways between discrete electrodes. This mode of operation can offer substantial advantages to create a truly concomitant plastic‐static system for integration in neuromorphic devices. However, critical aspects such as pathway controllability and stability are yet to be explored. In this study, pathway formation in self‐assembled neuromorphic networks formed by Ag nanowires decorated with TiO2 nanoparticles is investigated. Direct visualization of pathway formation through a neuromorphic network is attained using the lock‐in thermography technique. Using this technique, it is demonstrated that how networks preserve information from previously used pathways through increased local junction connectivity. This effect directly reshapes subsequent formation of pathways whenever the spatial location of the electrodes is dynamically changed. Combining these results with conventional current–voltage measurements, which show that the network electrically acts as a volatile switching memristor, a unique interaction between short‐term and long‐term memory arises. This produces unexpected collective dynamical states of potentiation and inhibition of network conductance whenever different spatiotemporal signals are dynamically fed to the network.

Application of N-doped carbon nanotube-supported Pt-Ru as electrocatalyst layer in passive direct methanol fuel cell

In this research, nitrogen-doped carbon nanotubes (N-CNT) were prepared through the low-temperature thermal method and used as the support material for the bimetallic catalyst PtRu and Pt nanoparticles. A passive single-cell direct methanol fuel cell (DMFC) was designed and fabricated to investigate and compare the performance of three discrete membrane electrode assemblies (MEA) with carbon black (CB), CNT, and N-CNT as the catalyst support, respectively. Adding N to the structure of CNTs remarkably improves the physical and electrochemical characteristics of the catalyst. More active sites and stronger interaction between support and metal particles lead to the formation of smaller metal clusters and higher surface area as well as superior electrochemical activity. Compared to PtRu/CB and PtRu/CNT, PtRu/N-CNT illustrate 32% and 12% higher surface area, 3 and 1.9 times higher MOR activity, and 62% and 18% higher power output (26.1 mW/cm2), respectively. Moreover, it is revealed that PtRu/N-CNT has long-term stability in the MOR. The research work presented in this paper exhibits the outstanding performance of Pt and PtRu supported on N-CNT in a passive single-cell DMFC.

The Energy Compensation of the HRG Based on the Double-Frequency Parametric Excitation of the Discrete Electrode.

In this study, for energy compensation in the whole-angle control of Hemispherical Resonator Gyro (HRG), the dynamical equation of the resonator, which is excited by parametric excitation of the discrete electrode, is established, the stability conditions are analyzed, and the method of the double-frequency parametric excitation by the discrete electrode is derived. To obtain the optimal parametric excitation of the resonator, the total energy stability of the resonator is simulated for the evolution of the resonator vibration with different excitation parameters and the free precession of the standing wave by the parametric excitation. In addition, the whole-angle control of the HRG is designed, and the energy compensation of parametric excitation is proven by the experiments. The results of the experiments show that the energy compensation of the HRG in the whole-angle control can be realized using discrete electrodes with double-frequency parametric excitation, which significantly improves the dynamic performance of the whole-angle control compared to the force-to-rebalance.

A Tunable Beamforming Ferroelectric Lens for Millimeter Wavelength Ranges

The advanced design of a millimeter-wave quasi-optical beamforming device (QOBD) based on the ferroelectric ceramic was elaborated and considered. Among the advantages of the proposed design are simplicity and cost-effectiveness in contrast to conventional analog and digital beamforming devices based on array antennas. The use of ferroelectric ceramic in the QOBD design allows operating in a wide frequency range up to 100 GHz. The advanced topology of discrete radiotransparent electrodes to provide a realization of different beamforming functions such as beam focusing and beam scanning was considered. The prototype of the proposed QOBD was designed to operate at 60 GHz. The measured radiation pattern of the QOBD prototype is in good agreement with the simulated one. Measurements demonstrate decreasing of beamwidth of the primary antenna radiation pattern by the lens prototype operating in the beam focusing regime.