Electrode Height Research Articles

In Situ and 2D and 3D in Silico Redox Cycling Studies for Design Optimization of Coplanar Arrays of Microband Electrodes in a 70 μm × 100 μm Electroactive Footprint

Optimization of redox-cycling currents was performed by adjusting the height (sidewalls, h), width (w), and length (l) of band electrodes and their spacing (w gap) in coplanar arrays restricted to a small-electroactive window of 70 × 100 μm. These arrays can function in μL-volumes for chemical analysis (e.g., in-vivo dopamine detection using probes). Experiments were conducted with an array of five electrodes (N E = 5), w = 4.3 μm, w gap = 3.7 μm, h = 0.150 μm, and l = 99.2 μm. Reasons for disparities between currents from experiments and approximate equations were determined by high-density mesh simulations and were found to arise from sluggish heterogeneous electron transfer kinetics and diffusion at electrode ends, edges, and heights. Ferricyanide, with its moderately slow kinetics, exhibits redox-cycling currents that fall below predictions by the equations as w gap decreases and diffusional flux outpaces reaction rates. Simulations aid investigations of various array designs, achievable through conventional photolithography, by decreasing w and w gap and increasing N E to fit within the electroactive window. A coplanar array, N E = 58, w = w gap = 0.6 μm, h = 0.150 μm and l = 100 μm, yielded ferricyanide sensitivities of 0.266, 0.259 nA·μM−1, enhancements of 8 × and 9 × over w = w gap = 4 μm, and projected dopamine lower limits of quantitation of 139 nM, 171 nM at generator and collector electrodes, respectively.

Fabrication of Flexible Capacitive Pressure Sensors by Adjusting the Height of the Interdigital Electrode

Fabrication of Flexible Capacitive Pressure Sensors by Adjusting the Height of the Interdigital Electrode

Sensitivity studies and optimization of an impedance-based biosensor for point-of-care applications

In this study, we examined the relationship between the sensitivity of interdigitated electrode (IDE) impedimetric biosensors and the gap between the IDEs. Our aim is to find an optimal design to maximize sensitivity. A three-dimensional COMSOL model was constructed for determining the effects of electrode gap, width, and height on impedance sensitivity, revealing a singular linear correlation with the inner gap. Considering both the simulation results and fabrication processes, we have developed three IDE prototype chips with electrode gaps of 3 μm, 4 μm, and 5 μm, respectively. For empirical validation, human anti-SARS-CoV-2 monoclonal antibody (mAb) was utilized, with immobilization of the SARS-CoV-2 spike protein on the chip's surface for mAb capture. This interaction, further amplified by Protein G conjugation, induced shifts in the impedance spectrum. The sensitivity of each prototype chip was evaluated across mAb concentrations ranging from 50 ng/mL to 500 ng/mL. The 3 μm configuration emerged as the most sensitive, demonstrating the ability to detect mAb concentrations as low as 50 ng/mL, a threshold unattainable by the other designs. This outcome underscores the critical influence of reduced inter-electrode gap on enhancing biosensor detection limits. The findings from this investigation offer a foundational approach for advancing biosensor sensitivity via electrode geometric optimization, with broad potential applications extending beyond COVID-19 diagnostics to a wide spectrum of clinical and research contexts.

Co-optimization of electrical-thermal–mechanical behaviors of an on-chip thermoelectric cooling system using response surface method

Thin-film thermoelectric coolers (TFTECs) have emerged as a potentially optimal solution for on-chip cooling. Most previous optimization studies have focused on improving the cooling performance of TFTECs. However, a fully functional and robust TFTEC requires a combination of performance, reliability, and power consumption in 3D integration with comprehensive consideration of electrical-thermal–mechanical coupling effects. In this work, a system-level co-optimization of an on-chip thermoelectric cooling system is performed using an electrical-thermal–mechanical coupling model. Response surface method is used to obtain predictive models to evaluate the performance of TFTEC with respect to leg height, electrode height, electrical and thermal contact resistances. The interactions between the design factors and their effects on device resistance, active cooling, and thermal stress are investigated. The results reveal that electrode height is the most critical factor affecting device resistance and active cooling. Leg height is the most important factor affecting maximum thermal stress. Based on multi-objective optimization, the optimal configuration of design factors is obtained. A device resistance of 5.75Ω, active cooling of 3.8°C, and thermal stress of 1646.2MPa can be achieved simultaneously. Compared to the initial configuration, device resistance is increased by 4.9%, active cooling is increased by 111%, and thermal stress is reduced by 3.4%.

Electric-field induced droplet stable vertical vibration: Experiments and numerical simulations

In this study, stable vertical vibration of a single droplet was stimulated through Electrowetting on Dielectric (EWOD) on a Polydimethylsiloxane-coated Indium Tin Oxide glass (PDMS-ITO) surface in an oil atmosphere. The mechanism of the vibration is clarified as a self-adjusted energy earning and losing equilibrium, and a small friction at the contact line is crucial for this stable vibration. We investigated the impact of needle tip electrode height, different voltage forms (AC and DC voltages), and voltage magnitude on the droplet vibration state. As decreasing the needle tip electrode height, there is a transition of the droplet from a vibrating state to a static equilibrium state. During the vibration, the vibration period remains constant regardless of tip height, but the contact angle changes synchronously with the voltage. The electric signal in the circuit is also measured to provide solid evidence for this synchronicity. Finally, the saturation voltage of the contact angle and amplitude is about 120 V. The intrinsic connection between contact angle saturation and amplitude saturation is clarified by studying the surface energy of the droplet. A theoretical model is constructed to numerically simulate the shape and amplitude of the droplet’s vibrations.

4D printing of shape-adaptive tactile sensor with tunable sensing characteristics

Using 4D printing to fabricate tactile sensors is promising, which will bring exciting functionalities to sensors, such as action self-sensing, environment self-adaptation, and self-healing. Here, we introduce 4D printing technology to fabricate the versatile smart tactile sensor with an adjustable measuring range and sensitivity, and shape adaptation for sensing in unstructured objects, which can sense touch from. The 4D-printed sensors (4DPS) with unique coplanar designs are achieved using a multi-material extrusion process for manufacturing interdigital electrodes composed of nanocarbon black/polylactic acid composites and shape memory polyurethane. The variability in the detection range and sensitivity stems from the changes in the electrode height and spacing caused by the deformation of shape memory polymer (SMP) under heat treatment. By setting printing parameters, not only can the diameter of the interdigital electrodes be precisely regulated, but 3D sensors that adapt to different curved surfaces can also be realized by utilizing thermal stress during the printing process. Moreover, the 4DPS is applicable to non-developable surfaces, such as spherical dome surfaces or saddle surfaces. Therefore, the shape-changing tactile sensor may offer great potential in environment self-adaptation and test range self-adjustment for human-robot cooperation in sensing.

A novel cascaded thin-film thermoelectric cooler for on-chip hotspot cooling

Thin-film thermoelectric coolers (TFTECs) are a potential solution for on-chip thermal management of power devices. However, substrate heat leakage, large TE leg resistance, and low integration level can degrade the performance of in-plane TFTECs, making it difficult to achieve large cooling temperature differences. Serious challenges still remain in the structural engineering of in-plane TFTECs, which need to be improved to fully exert the cooling performance. In this work, a novel cascaded in-plane TFTEC based on a flexible polyimide substrate is proposed to achieve high-efficiency on-chip hotspot cooling. The device is designed with a radial structure to increase the heat absorption area ratio. Two cascade rings are used to divide the device into three stages to enhance the heat flow in the planar direction and to further increase the number of legs and the cold end area. The effects of substrate thickness, cascade material, electrode height and leg height on the cooling performance are analyzed using the finite element method. When the substrate thickness is 25 μm, the electrode height is 5 μm, and the leg height is 5 μm, the cascaded in-plane TFTEC can achieve a minimum cooling temperature of −44.6 °C and a maximum cooling temperature difference of 69.6 °C at a current of 25 mA. The effect of contact resistance is limited to 4 % since the planar configuration can provide large-area contact.

Effect of Electrode/Electrolyte Coupling on Birnessite (δ-MnO2) Mechanical Response and Degradation.

Understanding the deformation of energy storage electrodes at a local scale and its correlation to electrochemical performance is crucial for designing effective electrode architectures. In this work, the effect of electrolyte cation and electrode morphology on birnessite (δ-MnO2) deformation during charge storage in aqueous electrolytes was investigated using a mechanical cyclic voltammetry approach via operando atomic force microscopy (AFM) and molecular dynamics (MD) simulation. In both K2SO4 and Li2SO4 electrolytes, the δ-MnO2 host electrode underwent expansion during cation intercalation, but with different potential dependencies. When intercalating Li+, the δ-MnO2 electrode presents a nonlinear correlation between electrode deformation and electrode height, which is morphologically dependent. These results suggest that the stronger cation-birnessite interaction is the reason for higher local stress heterogeneity when cycling in Li2SO4 electrolyte, which might be the origin of the pronounced electrode degradation in this electrolyte.

Colocalized Raman spectroscopy – scanning electrochemical microscopy investigation of redox flow battery dialkoxybenzene redoxmer degradation pathways

Non-aqueous redox flow batteries offer high voltages for grid-level energy storage technologies. However, decomposition of the redoxmers – redox-active molecules that make up the anolyte and catholyte in the negative and positive cell compartments – is an important challenge to overcome for long-term storage. Here, we present a spectroelectrochemical study of the catholyte candidate 2,3-dimethyl-1,4-dialkoxybenzene (C7) and its decomposition mechanisms in the presence of a model nucleophilic base, pyridine. We utilize colocalized Raman microscopy and scanning electrochemical microscopy (Raman-SECM) to quantify the chemical rates of decomposition and qualitatively identify the reaction intermediates and products. A detailed study on how the Raman-SECM parameters (electrode distance, substrate electrode, and laser focal height) influence the Raman signal of the charged catholyte C7•+ is presented. Using optimized conditions, we monitored the deprotonation of C7•+ via Raman spectroscopy and the subsequent hydrogen abstraction from solvent molecules to regenerate C7 via electrochemistry. Finite element modeling was used to fit electrochemical and spectroscopic data, quantifying the deprotonation rates as kdep = 2000 and 700 L mol−1s−1 and abstraction rates as kabs = 0.5 and 0.2 s−1 in propylene carbonate and acetonitrile solvents, respectively. Our results show the value of spatiotemporal resolution in evaluating the chemical and electrochemical behavior of materials for redox flow batteries.

Experimental investigation on the spray performance of industrial swirl nozzle assisted by ion wind

A method for improving the swirl nozzle spray performance using electric field is proposed. A pair of symmetrical needle electrodes is arranged perpendicular to the fuel injection direction. The influence of the electrode height and distance, along with that of the voltage between electrode pair on spray morphology are studied. The results show that when the electrodes are arranged at the fuel-film breakup height, the ion wind shortens the liquid film penetration length and increases the spray angle. The average fuel drop size is reduced by up to 35.8%. The distance between the electrodes also affects the atomization performance.

Effect of Process Parameters on Arc Behavior and Weld Formation in Weaving Gas Tungsten Arc Welding

The arc welding with weaving has been used widely to obtain better weld quality by avoiding lack of side wall fusion and improve the weld efficiency by obtaining the wide weld. But the effect of weaving process parameter on the weld is not clear. The aim of this work is to study the effect of process parameters on arc behavior and weld formation in Weaving-Gas Tungsten Arc Welding (W-GTAW), those parameters include welding current, tungsten electrode height from the electrode tip to upper surface of workpiece, weave angle, weave speed, and weave stop time on the left and right sides. The instantaneous arc shape and electrical signal data were collected by high-speed camera and electrical signal acquisition system, respectively. Furthermore, the weld morphology was also systematically analyzed. This result shows that the bottom surface radius of the arc changed with weaving in the W-GTAW. When the weave speed increased to 0.40 × 10−1 rad/s, the change of the radius was the least, with only 0.10 mm drift, and the difference between the arc forces in the middle and the two sides of the molten pool was smallest in all experiments. Compared with the welding stability of each process, decreasing the tungsten electrode height, weave angle and speed could significantly enhance the welding stability. The forming coefficient of weld with a weave angle of 1.9° was 3.11. It shows that increasing reasonably the weave angle and speed can increase the weld penetration and might help reduce stress concentration and hot crack tendency of the weld. When the welding current is reduced to 130 A for W-GTAW welding, the hardness transition from base metal (BM) zone to weld zone (WZ) is more gentle. Furthermore, the W-GTAW technology shows great application potential in weld forming control by adjusting process parameters.

High-performance transparent electromagnetic interference shielding film based on metal meshes

Transparent electromagnetic interference (EMI) shielding films have gained considerable attention for the commercialization of the 5G wireless technology based on electromagnetic waves in the GHz range. In this study, transparent EMI shielding films with embedded metal meshes on a 100 μm thick polyethylene terephthalate film for EMI shielding were fabricated using ultraviolet imprinting and Ag paste filling techniques. The various EMI shielding film types were fabricated by varying the width, aperture size, and height of the mesh electrode to evaluate the efficiency of the EMI shielding according to the incident electromagnetic wave frequency and morphology of the mesh metallic electrodes. The results indicate that the EMI shielding efficiency (SE) increased with a decrease in the aperture size of the metal mesh electrodes and an increase in their height. The average EMI SE values of the fabricated film in the 0.5–18 GHz range reached 48.3 dB and 59.6 dB at a light transmittance of approximately 90% and 77%, respectively. The fabricated EMI shielding films can be used for various applications, such as communications, aerospace, medical equipment, and military.

Performance assessment and optimization of a thin-film thermoelectric cooler for on-chip transient thermal management

On-demand cooling of thin-film thermoelectric cooler (TFTEC) is a promising technique for energy-saving and high efficiency. However, the transient cooling process of TFTEC is complex and systematic, involving temperature-dependent material properties, geometry factors, parasitic parameters and control parameters. In this work, a system-level optimization of the on-chip transient thermal management (TTM) performance of a Bi2Te3-based TFTEC is performed using a transient three-dimensional numerical model. The response surface method is applied to obtain a predictive model for evaluating the transient cooling performance of TFTEC in terms of four different design factors of thermoelectric leg height, electrode height, current pulse width and amplitude. The relationships between the above design factors and responses including passive cooling, active cooling, temperature overshoot, and time delay and their interactive effects are investigated. Finally, single- and multi-objective optimizations are employed to optimize these responses in different scenarios. The results show that the TFTEC with the optimal configuration enables a passive cooling of 15.57 °C and an active cooling of 5.85 °C simultaneously for a chip hotspot with a transient heat flux of 1300 W/cm2. Furthermore, the hotspot temperature can be limited to 7.15℃ lower than the predefined temperature limit, while the high-power pulse loading time can be extended by 690.2 ms.

The influence of stimulating electrode conditions on electrically evoked potentials and resistance in suprachoroidal transretinal stimulation.

To determine the influence of stimulating electrode conditions on the amplitudes and latencies of electrically evoked potentials (EEPs) and the resistance at the electrode-tissue interface in the suprachoroidal transretinal stimulation (STS) system. Experimental study. A scleral pocket (3 × 5 mm) was created just over the visual streak in anesthetized pigmented rabbits (weight, 1.9-2.7 kg), and STS stimulating electrodes were implanted into the pocket. Measurements were obtained with stimulating electrodes of different lengths (0.3 or 0.5 mm) and different surface characteristics (smooth or porous). EEPs elicited with a fixed current under each set of electrode conditions were recorded; three measurement sessions were performed for each rabbit. The resistance at each electrode-tissue interface was measured. The latencies and amplitudes of the EEPs did not differ significantly with changes in the height and surface characteristics of the stimulating electrodes, but the resistances at the electrode-tissue interface differed significantly (P = 0.001; the resistance values for the 0.3-mm-long electrode with a porous surface was 5.24 ± 0.67 kΩ and with the 0.3- and 0.5-mm-long electrodes with smooth surfaces were 7.63 ± 0.12 kΩ and6.77 ± 0.20 kΩ). Being shorter did not affect the EEPs of the stimulating electrodes with a porous surface while decreasing the resistance at the electrode-tissue interface.

Trapping of a Single Microparticle Using AC Dielectrophoresis Forces in a Microfluidic Chip.

Precise trap and manipulation of individual cells is a prerequisite for single-cell analysis, which has a wide range of applications in biology, chemistry, medicine, and materials. Herein, a microfluidic trapping system with a 3D electrode based on AC dielectrophoresis (DEP) technology is proposed, which can achieve the precise trapping and release of specific microparticles. The 3D electrode consists of four rectangular stereoscopic electrodes with an acute angle near the trapping chamber. It is made of Ag-PDMS material, and is the same height as the channel, which ensures the uniform DEP force will be received in the whole channel space, ensuring a better trapping effect can be achieved. The numerical simulation was conducted in terms of electrode height, angle, and channel width. Based on the simulation results, an optimal chip structure was obtained. Then, the polystyrene particles with different diameters were used as the samples to verify the effectiveness of the designed trapping system. The findings of this research will contribute to the application of cell trapping and manipulation, as well as single-cell analysis.

The modelling and simulation of perovskite solar cell consisting textile-based electrodes

Perovskite solar cell (PSC) consisting textile-based electrodes has been created novel features for future energy supply. Recently, Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 perovskite has appeared as a favourable candidate for flexible perovskite solar cells. However, a confined performance was acquired when the conventional Spiro-OMeTAD were used as hole transport layer (HTL) material because of suboptimal valance band offset (ΔEV) between Perovskite/HTL layers. In this study, a theoretical drift–diffusion​ modelling is used by finite volume method (FVM) to investigate performance of textile perovskite solar cell with double hole transport layers (HTLs) with graded band gap energies. Copper thiocyanate (CuSCN) and Nickel Oxide (NiO) are replaced as double HTLs, which dramatically enhanced the performance due to optimal upward step by step valance band offsets (ΔEV) between Perovskite/Textile Composite Electrode layers. It is shown that the decreasing of the metal–semiconductor schottky barrier height of electrodes leads to significant increase in fill factor (FF). Also, it is revealed that the enriching of perovskite carrier diffusion length by equipoising of carrier capture cross section, carrier total defect density and carrier thermal velocity substantially promote the overall device efficiency. The short-circuit current (Jsc) of 20.65 mA/cm 2, open-circuit voltage (Voc) of 1.19 V, fill factor (FF) of 73.57%, and power conversion efficiency (PCE) of 18.20% have been obtained by optimization of electrodes properties and perovskite layers. Remarkably, the advantageous of low cost, flexible, and chemical stable conducive textile composite, extends new opportunities in the commercial expansion of highly efficient photovoltaic textile in optoelectronic industry field.

Arc Characteristics of Ultrasonic-Magnetic Coaxial Hybrid GTAW.

Ultrasonic-magnetic field coaxial hybrid GTAW(U-M-GTAW) is a new non-melting electrode welding method proposed by combining ultrasonic assisted GTAW(U-GTAW) and magnetic assisted GTAW(M-GTAW) on the regulation characteristics of the GTAW arc. U-M-GTAW introduces ultrasonic and magnetic field effects into GTAW to improve arc characteristics. The orthogonal experiment was designed to investigate the degree of influence of different process parameters on the arc. The degree of influence of ultrasonic power P, radiator height H, magnetic field current CW, welding current CW and tungsten electrode height HT on ΔL1 (degree of arc root diameter change), ΔL2 (degree of maximum diameter change) and ΔS (degree of area change) were analyzed. In the parameter range, P has the greatest degree of influence on ΔL1 and ΔL2. As all process parameters increase, L1 shows a tendency to decrease, indicating an increase in the compression of the arc root. ΔL2 with the increase in P and CW shows a trend of first decreasing and then increasing. ΔL2 with the increase in H decreases, indicating that the acoustic radiation force increases, the arc energy increases, and the dark region decreases. The magnetic field current increases, the bottom of the arc expands, and the height of the tungsten electrode increases, the arc dispersion and thus the difference between the dark and luminous regions at the bottom increases, resulting in ΔL2 with the increase in CM and HT increases. CW has the greatest degree of influence on ΔS. ΔS decreases and then increases as P and H increase, which indicates that the force on acoustic radiation increases and then decreases in the range. An increase in the magnetic field current increases the rotation of the arc, leading to an increase in the arc area. An increase in welding current leads to an increase in arc energy, expansion of the arc morphology, and an increase in ΔS. The tungsten electrode height increases, the arc diverges, the dark region increases, the luminous area decreases, and ΔS increases. Finally, combined with the analysis of ultrasonic field and magnetic field theory, changes in process parameters will affect the force of the arc and thus the arc morphology. The U-M-GTAW arc under the action of acoustic radiation force, the plasma flow is shifted in the direction of the arc axis, and the arc contraction, under the action of magnetic field force to generate circumferential current, the arc undergoes periodic rotation, which improves GTAW arc characteristics.

High-Performance SAW Low Temperature Sensors with Double Electrode Transducers Based on 128° YX LiNbO3.

Low temperature measurement is crucial in deep space exploration. Surface acoustic wave (SAW) sensors can measure temperature wirelessly, making them ideal in extreme situations when wired sensors are not applicable. In this study, 128° YX LiNbO3 was first introduced into low temperature measurements for its little creep or hysteresis in cryogenic environments and affordable price. The finite element method was utilized to raise the design efficiency and optimize the performance of SAW sensors by comparing the performance with different interdigital transducer (IDT) structure parameters, including the height of electrodes, pairs of IDTs, reflecting grid logarithm and acoustic aperture. Once the parameters were changed, a novel design of high-performance SAW temperature sensors based on 128° YX LiNbO3 with double electrode transducers was obtained, of which the Q value could reach up to 5757.18, 4.2-times higher than originally reported. Low temperature tests were conducted, and the frequency responsiveness of SAW sensors was almost linear from -100 °C to 150 °C, which is in good agreement with the simulation results. All results demonstrate that double electrode transducers are considerably efficient for performance enhancement, especially for high-Q SAW sensors, and indicate that LiNbO3 substrate can be a potential high-performance substitute for cryogenic temperature measurements.

Effect of surface topography on dendritic growth in lithium metal batteries

Lithium (Li) metal, which has the advantages of high theoretical capacity, low redox potential, and low density, is considered an ideal anode material for next-generation battery systems. However, the dendritic morphology of Li-metal electrodeposition during the charging process remains challenging because it results in active Li depletion, poor cycling performance, and safety issues. Herein, the effect of surface topography on dendrite growth was quantitatively revealed by an electro-chemo-mechanical phase-field model. The surface topography of the Li-metal battery was measured and quantified using the arithmetic mean roughness (Ra), root mean square roughness (Rq), impulse factor (Rp), skewness, and kurtosis. The simulation results revealed that the arithmetic mean height of the bare electrode and the height of the highest tip compared to the average height were highly correlated with dendrite growth. It was also demonstrated that controlling the surface topography, applied voltage, and external pressure can effectively suppress dendritic growth. Furthermore, the exposed surface of the electrode generated by the size difference or misalignment of the electrodes induced considerable dendrite growth. We believe that our quantitative analysis provides guidance for processing the surface roughness of practical Li-metal batteries.

Improved electrical properties of encapsulated MoTe2 with 1T′ edge contacts via laser irradiation

Transition metal dichalcogenides (TMDCs) encapsulation is an essential technology for improving electron transport and preventing external contamination in practical applications. Nevertheless, Ohmic contacts in TMDCs continue to pose many problems. A laser was irradiated along with MoTe2 encapsulated in h-BN and edge contact electrodes. We studied the properties of the edge contact resistance, in which the crystal structure of MoTe2 changes from a semiconductor hexagonal phase (2H) to a metallic monoclinic phase (1T′). The contact between TMDCs and the metal electrode, Fermi-level pinning, contact resistance, and Schottky barrier height (SBH) can be calculated. Laser irradiation of the edge contact confirmed that, due to the change in the crystal structure of MoTe2, a reduction in contact resistance by over a factor of three resulted in the development of the electrical properties of the device. Field-effect transistors (FETs) with indium (In) edge contact exhibit high performance, with the highest electron mobility reaching 7.9 cm2V−1s−1 at 300 K. Furthermore, the barrier heights for In with a MoTe2 junction were 10.3 meV after laser irradiation, which is more than ten times the low SBH. This study confirms the improved electrical properties of the two-dimensional material and metal were confirmed using a laser.