Search Results (974)

To improve the threshold accuracy of inertial switches, this study proposes a monolithic metal MEMS inertial switch with nonlinear springs. The switch uses two sets of inclined beams with asymmetric initial angles as suspension springs. Geometric nonlinearity produces low displacement sensitivity away from the design threshold and high sensitivity near the threshold. This response improves threshold discrimination and reduces the deviation between the actual and design thresholds. A nonlinear switch and a linear reference switch are designed with the same static threshold of 27.5 g. Their responses are compared using Abaqus static and explicit dynamic simulations. Both switches are monolithically fabricated from 50 μm thick 304 stainless steel by induction-electrode through-mask electrochemical micromachining (IETMEMM). Key dimensional deviations are below 2.5%. Drop-weight tests show measured nonlinear-switch thresholds of 27.8, 27.8, 26.9, and 25.4 g under half-sine shocks with pulse widths of 4, 6, 8, and 10 ms, respectively. The maximum threshold deviation is 2.1 g. The overall threshold accuracy is 92.4%, substantially higher than the 56.0% of the linear reference switch. This work combines a nonlinear threshold-regulation mechanism with monolithic IETMEMM fabrication and provides a new strategy for metal MEMS inertial switches with high threshold accuracy. Full article

The simultaneous measurement of biopotential and neurochemical signals provides a comprehensive view of the brain. Yet, most neural interfaces record solely biopotential or neurochemical activity. This work presents a complementary metal-oxide-semiconductor (CMOS) analog front-end (AFE) chip that integrates 32 biopotential amplifiers and 32 neurochemical amplifiers for parallel recording from 64 electrodes. The biopotential amplifier is a two-stage design providing a gain of 57.1 dB, a bandwidth of 0.4 Hz–6.2 kHz, and 6.7 µV_RMS input-referred noise (20 kHz sampling rate). The neurochemical amplifier is a rail-to-rail folded-cascode operational amplifier with selectable transimpedance gain (91.9 kΩ to 851.9 kΩ), a dynamic range of ±15 μA to ±2 μA, respectively, a bandwidth of 12.6 kHz, and input-referred noise as low as 46.3 pA_RMS (20 kHz sampling rate). The neurochemical amplifiers are designed for fast-scan cyclic voltammetry (FSCV) measurements. I/O complexity is minimized using a time-division multiplexing scheme for readout, enabling straightforward scalability. The chip is fabricated using a 0.35-µm CMOS process and occupies a 3.0 × 8.3 mm² area. In vitro recordings of catecholamines and neural spikes validate the chip’s function. The chip enables scalable, low-noise, bimodal neural recording, supporting investigations into the dynamics between neuronal biopotential activity and neurochemical signaling. Full article

Electromyography (EMG)-based sensing is an important tool for assessing neuromuscular activity and monitoring athlete development; its reliability depends on electrode placement, signal quality, and accurate identification of muscle activation periods. This study proposes an intelligent EMG sensing framework integrating preliminary electrode placement assessment, muscle activity detection, feature extraction, and regression-based progression prediction. A placement assessment indicated that positioning the electrode adjacent to the innervation zone produced the highest RMS under the tested conditions. A two-stage activity detection method based on clustering and probabilistic modeling achieved an average error of 1.5% and a temporal deviation of 19 ms. Nine time-domain EMG features extracted from the detected activity segments were used to characterize athlete progression and estimate the time required to reach a reference neuromuscular profile. Among the methods, Linear Regression provided the best fit to the data, obtaining R² = 0.987 and RMSE = 4.21 and suggesting a predominantly linear relationship between the EMG-derived features and training duration within the dataset. However, these results were obtained from only six longitudinal observation periods for a single representative athlete, with each period represented by a 90-dimensional EMG feature vector derived from the ten movement classes. Therefore, the results should be interpreted as preliminary, athlete-specific goodness-of-fit findings rather than evidence of generalizable predictive performance. Validation using larger longitudinal cohorts and independent datasets is required. The proposed framework is compatible with future IoT-enabled wearable and edge-computing architectures; however, hardware-level implementation was beyond the scope of this study. Full article

To address the limitations of traditional trench electrode silicon detectors, such as charge collection dead zones and non-uniform electric fields, this paper proposes a novel 3D silicon detector based on an interleaved trench electrode structure. By constructing interleaved N-type and P-type heavily doped trenches on a lightly doped N-type substrate, enhanced uniformity and depth profile optimization of the electric field distribution are achieved. Moreover, 3D numerical simulations based on TCAD demonstrate that the proposed structure provides a uniform, planar-like electric field distribution; reduces low-field regions; and enables fast carrier collection with a low full-depletion voltage. The results provide a theoretical basis and design reference for the development of novel 3D radiation detectors with low depletion voltages, fast charge collection, and favorable radiation response characteristics. Full article

Sulfur dioxide (SO₂) is a preservative used in the production of fermented beverages for its antimicrobial and reducing properties. However, its effect on the oxidation–reduction potential (ORP, redox potential) during alcoholic fermentation of apple cider has never been recorded. In this study, freshly pressed apple juice was fermented with a 30 mg/L free SO₂ addition (RED) and without an SO₂ addition (CON) prior to alcoholic fermentation. Fermentation kinetics, ORP, basic chemistry, organic acids, nitrogenous compounds, free and total SO₂, glutathione (GSH), phenolics, and volatiles were monitored during alcoholic fermentation and at racking. Additionally, sensory analysis was conducted after bottling. Sulfur dioxide had no effect on fermentation kinetics, nitrogen utilization, ethanol yield, or the volatile composition of the apple ciders at racking. The ORP (vs. Ag/AgCl reference electrode) reached maximum values of 310 mV in CON and 218 mV in RED before alcoholic fermentation, and minimum values of −94 mV and −136 mV, respectively, near peak alcoholic fermentation. Mean ORP values during alcoholic fermentation were −29 mV in CON and −47 mV in RED. No statistical differences were found between the ORP of CON and RED using net area under the curve (AUC) of the ORP relative to Y = 0 mV, nor in the GSH chemistry of the ciders. The addition of SO₂ inhibited malolactic fermentation (MLF) during alcoholic fermentation. As a result, higher concentrations of malic acid and lower concentrations of lactic acid were observed in RED than in CON at racking. Sulfur dioxide additions preserved monomeric, dimeric, and increased the pool of sulfonated flavan-3-ols, likely due to PPO inhibition during the prefermentative phase and reactive oxygen species (ROS) quenching. The sensory composition of the ciders was affected whereby CON showed higher banana aroma and RED trended towards reduction aromas. Overall, SO₂ additions before alcoholic fermentation of apple cider preserved phenolics, inhibited MLF, and increased reduction aroma with no clear effect on fermentation kinetics and ORP, highlighting trade-offs between the impact of SO₂ additions on the chemical and sensory attributes of apple cider. Full article

The limitations of conventional inorganic electrodes call for organic alternatives for advanced energy storage. Metal–covalent organic frameworks (MCOFs) integrate the metal active sites of metal–organic frameworks (MOFs) with the high chemical stability imparted by strong covalent bonds in covalent organic frameworks (COFs) while retaining the high specific surface area and tunable porosity of both material classes. Among these, MCOFs constructed from porphyrin and phthalocyanine building units have emerged as a research hotspot in electrochemical energy storage owing to their inherent 18π-conjugated macrocyclic electronic systems, well-defined M–N₄ coordination sites, and potential bipolar charge storage characteristics. This review systematically summarizes recent advances in this class of materials. First, from the perspective of metal center introduction timing, three core synthetic strategies—pre-metallation, simultaneous metallation, and post-metallation—are categorized and evaluated in terms of coordination precision, synthetic efficiency, and scalability potential. Second, the regulatory effects of two-dimensional layered and three-dimensional interpenetrated structures on charge transport pathways and structural stability are elucidated. Subsequently, the applications of porphyrin/phthalocyanine-based MCOFs in lithium-based batteries, zinc-based batteries, sodium/potassium-ion batteries, and supercapacitors are reviewed in detail, with emphasis on the key roles of metal active sites in catalytic conversion, chemical anchoring/confinement, interface stabilization, and pseudocapacitive contribution. Finally, future directions to address key performance and mechanistic bottlenecks are discussed. This review aims to provide a systematic reference for the rational design and energy storage applications of high-performance porphyrin/phthalocyanine-based MCOFs. Full article

A flexible integrated composite electrode is fabricated using NiV-layered double hydroxide (NiV-LDH) nanosheets grown perpendicularly onto a Ti₃C₂T_x MXene-incorporated carbon nanofiber scaffold (MXene/CNFs). This hybrid structure, prepared by electrospinning and a hydrothermal treatment, is referred to as NiV-LDH@MXene/CNFs. Constructed from a conductive MXene/CNF scaffold and vertically aligned NiV-LDH nanosheets, the integrated flexible electrode offers uninterrupted electron transport, good flexibility, abundant active sites, and strong interfacial cohesion, thereby obviating the use of polymeric binders and conductive additives. The hydrophilic nature of MXene and the three-dimensionally interconnected porous structure favor rapid electrolyte uptake and ion diffusion. As a result of these synergistic effects, the composite exhibits a specific capacitance of 614 F g⁻¹ at 1 A g⁻¹ and retains 60% of its initial capacitance after 10,000 cycles at 5 A g⁻¹ in a three-electrode cell. An asymmetric supercapacitor made of this material and activated carbon achieves 68.75% capacitance retention under the same cycling protocol at 5 A g⁻¹ and shows a stable open-circuit voltage of 1.37 V. Two cells in series are capable of lighting a 3 V LED strip. Overall, this work validates an effective strategy to prepare high-capacity, robust, and binder-free flexible electrodes for advanced energy-storage applications. Full article

This study aimed to analyze the relationships between the electrical properties of fresh seed melon pulp and storage conditions, thereby providing a rapid electrical method for quality evaluation. The electrical parameters of fresh seed melon were measured using the parallel-plate electrode method at different storage temperatures of 4 °C, 8 °C, 12 °C, 16 °C, and 20 °C, and storage times of 0, 2, 4, 6, and 8 h. The relationships between electrical parameters and quality attributes at different frequencies were further investigated. An adaptive neuro-fuzzy inference system (ANFIS) model was established to predict the quality characteristics of fresh seed melon, with electrical parameters used as input variables and quality characteristics used as output variables. Eight membership function models were constructed and compared to select the optimal prediction model. The results showed that, with increasing frequency, the impedance (Z), capacitance (Cp), and resistance (Rp) of fresh seed melon decreased, while conductance (G) and reactance (X) increased at different storage temperatures. At different storage times, Z, quality factor (Q), Cp, and Rp decreased, while G and X increased with increasing frequency. The variation ranges of Z, Cp, Rp, G, and X gradually decreased at higher frequencies. Significant correlations between electrical parameters and quality characteristics were observed at the characteristic test frequency of 163.28 kHz. The ANFIS results showed that gauss2mf was the optimal model for predicting cohesiveness (Co, R² = 0.9491), pimf was the optimal model for predicting chewiness (Ch, R² = 0.9595), and gbellmf was the optimal model for predicting resilience (Re, R² = 0.9596). These results indicate that the combination of electrical properties and the ANFIS model has potential for evaluating the quality characteristics of fresh seed melon under the present experimental conditions. This study provides a theoretical basis for quality detection and storage preservation of fresh seed melon and offers a reference for the development of rapid electrical quality-evaluation techniques for seed melon pulp. Full article

Taking a typical high-power microwave power supply system as the research object, this paper quantitatively simulates and compares electromagnetic disturbance characteristics under multiple operating conditions, systematically investigates the influence mechanism of the system on EMI, and verifies the proposed simulation model via prototype experiments. Firstly, the typical equipment composition and three operating modes of the system are elaborated. Standardized high-frequency equivalent circuits of thyristors, capacitors, and inductors are established, and parasitic parameters are extracted to construct a system-level high-frequency coupling model. Different from traditional static parasitic extraction and separated field-circuit simulation methods, the proposed global collaborative optimization co-simulation method with voltage-dependent thyristor parasitic model significantly improves EMI prediction accuracy under full-cycle multi-mode operation. Secondly, based on the dynamic device characteristics under resonant charging, energy recovery and energy supplement modes, the generation mechanisms of EMI are clarified with quantitative data. During modeling, the electrical characteristics of thyristor body diodes and inter-electrode capacitances are fully incorporated with reference to actual component parameters. The EMC co-simulation based on CST field-circuit coupling is adopted to collaboratively optimize all parameters, which reduces the approximation error introduced by local modeling and greatly improves simulation accuracy. Combined with simulation and prototype experimental verification, this paper reveals the multi-path EMI coupling mechanism of pulsed power systems. The proposed parasitic parameter-based SPICE modeling and field-circuit co-simulation method can provide quantitative analysis tools and theoretical support for the EMC suppression design of high-power microwave power supplies. Full article

In this study, a novel SiC/rGO nanocomposite-modified glassy carbon electrode (SiC/rGO/GCE) was developed as a simple, cost-effective, and efficient electrochemical platform for metronidazole (MTZ) detection. The combination of silicon carbide (SiC) and reduced graphene oxide (rGO) provides a favorable interface with a high electroactive surface area, efficient electron transfer, and enhanced electrocatalytic activity. The mor-phology and surface characteristics of the modified electrode were investigated by scan-ning electron microscopy (SEM), while its electrochemical properties were evaluated by cyclic voltammetry and electrochemical impedance spectroscopy. The results confirmed successful electrode modification and improved electron-transfer kinetics compared with the bare GCE. The main experimental parameters were systematically optimized, with the optimum conditions established at pH 10, an accumulation time of 300 s, and an accu-mulation potential of 0.5 V. Under these conditions, the SiC/rGO/GCE exhibited a broad linear response to MTZ over the concentration range of 5–5000 µmol/dm³, with a detection limit of 0.5 µmol/dm³ (S/N ≥ 3). The enhanced analytical performance is attributed to the synergistic contribution of rGO and SiC, where rGO promotes rapid electron transport and provides a large electroactive surface, while SiC contributes additional active sites and structural stability. The sensor was successfully applied to pharmaceutical samples, providing recoveries of 99.85–102.29% with RSD values below 2%. These results demon-strate the practical potential of the proposed sensor for reliable MTZ determination. Fur-ther validation in food and biological matrices and comparison with reference chromato-graphic methods will be necessary to establish its broader analytical applicability. Full article

Electrochemical CO₂ reduction reaction (eCO₂RR) is a promising technology for carbon utilization, yet achieving high product selectivity and long-term stability remains a critical challenge. In this study, we investigated the performance and surface stability of Cu electrodes modified with Ag nanoparticles using a spray-coating method. While a bare Cu reference electrode exhibited an initial starting period dominated by hydrogen evolution before shifting toward hydrocarbon production after two hours, the Ag-spray-coated Cu electrode demonstrated immediate and stable catalytic activity. Electrode potential remained stable throughout the 12 h evaluation, in contrast to the negative shifts observed with the bare Cu electrode. Ambient pressure hard X-ray photoelectron spectroscopy (AP-HAXPES) revealed that while the bare Cu surface remained metallic, the Ag-spray-coated Cu surface existed as Cu₂O during the reaction. The enhanced selectivity and stability are attributed to a spillover mechanism, where CO generated on the Ag nanoparticles migrates to adjacent Cu₂O sites, inhibiting hydrogen evolution and facilitating efficient reduction to methane and ethylene from the onset of electrolysis. These findings demonstrate that surface modification via nanoparticle spray coating is a highly effective strategy for achieving selective and stable CO₂ conversion on bimetallic catalysts. Full article

Metal atoms or ions originating from interconnects, electrodes, or diffusion-barrier layers can migrate into oxide dielectrics during thermal annealing, causing insulation degradation, leakage-path formation, capacitance variation, and interfacial reaction. This work proposes an electrical test-element-group (TEG)-based monitoring framework that jointly evaluates metal diffusion and reaction-interlayer formation in oxide dielectrics. A Fick–Arrhenius diffusion model is used to calculate a continuous metal concentration profile, while a parabolic reaction model describes the growth of an interfacial reaction layer. The concentration profile and reaction-layer thickness are then coupled to integral resistance and series-capacitance models for adjacent-electrode resistance TEGs and vertical capacitance TEGs, respectively. A physics-informed simulation dataset was generated over a broad range of thermal, material-library, and geometry parameters, and measurement uncertainty was introduced to emulate inline electrical test conditions. XGBoost regression and classification models were then trained to inversely extract the 1% diffusion front, reaction-interlayer thickness, and process-risk class from the simulated electrical responses. With a calibrated material-library feature set, the model achieved an R² of 0.959 for diffusion-front extraction, an R² of 0.802 for interlayer-thickness extraction, and a risk-classification accuracy of 93.86%. The results show that resistance TEGs mainly capture lateral conductive-path formation, whereas capacitance TEGs are more sensitive to vertical interlayer formation and dielectric degradation. The proposed framework provides a non-destructive route for monitoring diffusion- and reaction-induced process risks using inline electrical measurements. The present work is based on model-generated datasets; material-specific deployment requires calibration using SIMS, TEM/EDS, XPS, C–V, I–V, or reference TEG data. Full article

The high soil resistivity in desert, Gobi, and barren land regions limits the lightning current dissipation capability of conventional needle-type grounding electrodes, thereby increasing the lightning-related risk to transmission lines. To address this issue, a three-dimensional transient simulation model of a horizontal needle-type grounding electrode equipped with grounding modules was developed in COMSOL Multiphysics (version 6.2) based on electromagnetic field theory and the nonlinear ionization characteristics of soil. The effects of the number, spacing, and downward inclination angle of the needles, as well as the geometric dimensions of the grounding modules, on the impulse grounding resistance and current dissipation characteristics were systematically investigated. The simulation results indicate that the needle-tip effect and mutual shielding effect between adjacent needles are the primary factors governing current dissipation performance. Increasing the number and spacing of the needles improves the grounding performance. Among the discrete inclination angles investigated, intermediate inclination angles generally exhibited relatively low impulse grounding resistance; however, the differences among the inclination angles were small, and the inclination angle corresponding to the minimum impulse grounding resistance varied with the critical soil ionization field strength. Under the baseline conditions of a 10 kA impulse current and an initial soil resistivity of 1000 Ω·m, the resistance reduction provided by the grounding modules decreased from 15.34% for one bilateral needle unit to 12.62% for nine units. Increasing the needle spacing from 0.3 to 1.1 m reduced the impulse grounding resistance by 18.09% and 11.38% for the configurations with and without grounding modules, respectively. Increasing the module radius from 0 to 0.25 m produced a 29.03% reduction in impulse grounding resistance, although the incremental resistance-reduction benefit gradually diminished as the module dimensions increased. These findings provide a theoretical reference for optimizing transmission-line tower grounding systems in high-resistivity desert, Gobi, and barren land regions. Full article

Hydrogel-forming microneedles (HFMNs) are minimally invasive interfaces that access interstitial fluid (ISF) through skin penetration, swelling-mediated uptake, analyte diffusion, and hydrated sensor integration. This review examines HFMN architectures, skin–device interfaces, ISF transport, molecular-recognition and signal-transduction strategies, analytical performance, benchmarking, wear-associated failure modes, therapeutic monitoring, and translational priorities. The field has expanded from glucose sensing to metabolites, ions, hormones, proteins, nucleic acids, microbial and wound biomarkers, and therapeutic drugs, enabled by advances in hydrogel chemistry, conductive networks, nanostructured electrodes, catalysis, affinity recognition, molecular imprinting, optical readouts, and multiplexed wearables. Performance remains context dependent and requires physiological range, calibration stability, biofouling resistance, reliable insertion, validated ISF-reference correlations, and interpretable thresholds. Evidence is strongest in artificial matrices, ex vivo tissue, and animals, while human validation remains limited. Translation will require standardized mechanics and transport reporting, longer wear studies, sterilization-compatible chemistries, scalable manufacturing, and clinical validation. HFMNs may complement rather than replace blood-based diagnostics. Full article

Reproducible electrode placement remains a critical, unresolved challenge in wearable ECG systems, where manual electrode attachment introduces inter-session positional error that degrades signal morphology and compromises multi-lead representation. Although the 12-lead clinical ECG system is the gold standard, conventional setups are often bulky, wired, and dependent on operator expertise, limiting their use in prehospital or remote care. Recent advancements in wearable and wireless ECG systems have improved mobility and real-time monitoring, but they typically suffer from limited lead coverage, discomfort, and unstable connectivity. This paper introduces BioShield-12, an anatomically adaptive thermoplastic polyurethane (TPU) shield fabricated using fused deposition modeling (FDM) to improve multi-site electrode placement and 12-lead electrocardiogram (ECG) reconstruction from a single-shield design based on anthropometric data from ten healthy adults (five male, five female; sizing cohort). Mechanical characterization confirmed TPU’s suitability as a compliant wearable substrate, with toughness of 34.4 MJ/m³ and elastic modulus of 79.1 MPa. Feasibility validation against a research-grade reference (BIOPAC MP36) in twenty healthy subjects (n = 20; 10 male, 10 female; mean age 21 ± 4 years) demonstrated consistent signal fidelity (SNR: 17.5–22.5 dB; Pearson r: 0.93–0.98; power-line interference ratio (PLIR): 1.0–3.2 × 10⁻⁵) and confirmed feasibility of 12-lead reconstruction. This work provides proof-of-concept for an additive manufacturing-based conformal electrode interface that eliminates variability in placement without needing individual attachment. Full article