Search Results (3,090)

This study presents a high-performance MEMS accelerometer employing a symmetrical differential ‘sandwich’ capacitive structure. An orthogonal rectangular compensation method was integrated with wet anisotropic etching to achieve high structural symmetry. An innovative glass–silicon composite cover plate was adopted, and the upper and lower plates were encapsulated by a sensitive structure via anodic bonding, which effectively reduced the parasitic capacitance. Simulations confirmed sufficient separation between the sensitive-axis (Z-axis) resonant frequency and orthogonal/torsional modes, ensuring low cross-axis coupling. The fabricated device exhibits high sensitivity (0.2216 V/g) and excellent linearity (99.842%) within a 0–8 g range. Furthermore, it demonstrates outstanding noise (7.88 µg/√Hz) and bias-instability (6.39 µg) performance, positioning it competitively against commercial counterparts. The proposed design and process offer a viable technical route for high-precision inertial sensing applications. Full article

Background: Arterial stenosis produces nonlinear changes in vascular impedance that are challenging to investigate in real time using either benchtop flow phantoms or high-fidelity computational fluid dynamics (CFD) models. Objective: This study aimed to develop and evaluate a low-cost printed circuit board (PCB) analog capable of reproducing the hemodynamic effects of progressive arterial stenosis through an R–L–C mapping of vascular mechanics. Methods: A lumped-parameter (0D) electrical network was constructed in which voltage represented pressure, current represented flow, resistance modeled viscous losses, capacitance corresponded to vessel compliance, and inductance represented fluid inertance. A variable resistor simulated focal stenosis and was adjusted incrementally to represent progressive narrowing. Input U_in, output U_out, peak-to-peak V_pp, and mean V_avg voltages were recorded at a driving frequency of 50 Hz. Physiological correspondence was established using the canonical relationships. $R={\displaystyle \frac{8\mu l}{\pi r^4}}$, $L={\displaystyle \frac{pl}{\pi r^2}}$, $C={\displaystyle \frac{3\pi r^3}{2Eh}}$, where μ is blood viscosity, ρ is density, E is Young’s modulus, and h is wall thickness. A calibration constant was applied to convert measured voltage differences into pressure differences. Results: As simulated stenosis increased, the circuit exhibited a monotonic rise in U_out and V_pp, with a precise inflection beyond mid-range narrowing—consistent with the nonlinear growth in pressure loss predicted by fluid dynamic theory. Replicate measurements yielded stable, repeatable traces with no outliers under nominal test conditions. Qualitative trends matched those of surrogate 0D and CFD analyses, showing minimal changes for mild narrowing (≤25%) and a sharp increase in pressure loss for moderate to severe stenoses (≥50%). The PCB analog uses a simplified, lumped-parameter representation driven by a fixed-frequency sinusoidal excitation and therefore does not reproduce fully characterized physiological systolic–diastolic waveforms or heart–arterial coupling. In addition, the present configuration is intended for relatively straight peripheral arterial segments and is not designed to capture the complex geometry and branching of specialized vascular beds (e.g., intracranial circulation) or strongly curved elastic vessels (e.g., the thoracic aorta). Conclusions: The PCB analog successfully reproduces the characteristic hemodynamic signatures of arterial stenosis in real time and at low cost. The model provides a valuable tool for educational and research applications, offering rapid and intuitive visualization of vascular behavior. Current accuracy reflects assumptions of Newtonian, laminar, and lumped flow; future work will refine calibration, quantify uncertainty, and benchmark results against physiological measurements and full CFD simulations. Full article

Nickel is widely deployed in caustic service, yet its native Ni(OH)₂/NiOOH passive film raises concerns for long service life. Graphene has emerged as a promising corrosion barrier; however, its long-term durability in strongly alkaline media remains largely unexplored. The extended exposure period in a highly caustic solution is a novel aspect of the present work, distinguishing it from previous studies that predominantly examined short-term exposures or focused on neutral and acidic environments. Here, we present the systematic assessment of low-pressure CVD-grown multilayer graphene (MLG) coatings on Ni in highly caustic (0.5 M NaOH) for up to 80 days. Two architectures, a conformal, robust MLG coating (Gr_Ni) and a less robust film (Gr_Ni_DF), were benchmarked against bare Ni. PDP and EIS reveal that Gr_Ni initially delivers nearly 2 orders of magnitude enhancement, as evidenced by the low frequency impedance, accompanied by a broad, high-fidelity capacitive plateau; the impedance still maintains 1.3–1.5 orders of magnitude superior after prolonged exposure. In contrast, Gr_Ni_DF undergoes progressive degradation, affording a modest 2-fold benefit over time, consistent with defect-mediated electrolyte ingress. SEM morphologies further corroborate these trends, confirming the superior structural stability of Gr_Ni under extended alkaline immersion. Full article

Low-voltage instrumentation and control (I&C) cables in nuclear power plants are continuously exposed to gamma (γ) radiation within containment areas, leading to cumulative degradation of their polymer insulation over decades of operation. Since conventional mechanical aging assessments are destructive, this study establishes a non-destructive diagnostic framework using high-frequency dielectric spectroscopy. Cable samples with ethylene propylene rubber (EPR) insulation and chlorosulfonated polyethylene (CSPE) jackets were subjected to controlled γ-irradiation at doses up to 1200 kGy. The broadband dielectric response was analyzed along with derived novel diagnostic parameters from capacitance and loss tangent spectra and a machine learning AI algorithm. The results show a strong, material-dependent relationship between radiation dose and dielectric indicators. For EPR insulation, the central capacitance (CC) and (C × F × LF) exhibit high positive sensitivity for Black and White EPR materials, respectively, whereas for CSPE jackets, the central frequency (CF) shows a pronounced monotonic decrease with the radiation exposure. These findings enable a straightforward, transparent interpretation of dielectric data and implement a new, accurate method of irradiated cables diagnosis. Full article

The growing demand for efficient and sustainable energy storage has intensified interest in green materials known for their high-power density. In this work, we evaluated the electrochemical and electrical performance of coin-cell supercapacitors with activated carbon electrodes from palm kernel shell. Two activated carbons were obtained using KOH and ZnCl₂ as activating agents at 700 °C and then superficially modified with nitric acid. The KOH-activated carbon electrodes showed the highest specific surface area (1181 m² g⁻¹) and the best electrochemical behavior, reaching an average gravimetric capacitance of 56. ± 9.2 F g⁻¹. The coins were characterized electrically by series and parallel arrangements, yielding specific energy and specific power densities of 2.6 Wh kg⁻¹ and 475 W kg⁻¹, and 1.8 Wh kg⁻¹ and 353 W kg⁻¹, at 0.001 A and 0.75 V for parallel and series arrangements, respectively. Full article

This paper presents an improved switching strategy developed for the Modified Non-Inverting Step-Down/Up (MNI-SDU) DC–DC converter. Unlike previously studied switching strategies, the proposed approach changes the firing sequence and then the equivalent circuits without increasing the switching frequency. This switching technique alters the equations used to select the converter’s capacitors, enabling a different voltage ripple in the capacitors while maintaining the same capacitance as in the previous operation. The proposed switching technique is introduced with a theoretical explanation, and the feasibility of the proposed method is verified through experimental results on a 570 W prototype. The results indicate that the new operation reduces capacitor capacitance and achieves over 58% voltage ripple reduction for both capacitors, while preserving desired operation, specified capacitances, and voltage regulation. The proposed strategy provides a compact and effective solution for high-performance power converters in battery-regulated and renewable-energy systems. Full article

Two approaches are described for construction of a screen-printed planar electrode (SPE) for potentiometric determination of iodide ion. The first, involves preparation and application of iron(II) bathophenanthroline tetraiodoplumbate complex ([Fe(bphen)₃][PbI₄]), as a sensitive and selective electroactive sensing material in a potentiometric electrode for iodide determination. The second is the use of a nano-sized poly(aniline-co-thiophene) (PANI-co-PT) as a solid-contact material in a planar miniaturized configuration. The SPE displays a Nernstian response for iodide ion with a calibration slope of −58.81 ± 0.69 mV/decade (R² = 0.9998) over a wide concentration range (9.17 × 10⁻⁷–6.94 × 10⁻³ mol/L), low detection limit (6.09 × 10⁻⁷ mol/L), rapid response time (5.0 ± 1.0 s) and long-life span (75 ± 3.0 d). The use of PANI-co-PT solid-contact layer significantly improves the ion-to-electron transduction, eliminates the formation of undesired thin water layer between the sensing membrane and the conducting substrate, prevents membrane delamination, enhances potential stability with a significantly reduced potential drift (8.32 ± 0.12 µV/min) and displays high redox capacitance (2.560 ± 0.040 mF). Water contact angle measurements confirm the increased hydrophobicity of the modified membrane electrode (from 44 ± 0.8° to 93 ± 1.4°) and demonstrate the membrane ability to repel moisture and further stabilize the sensor response. The proposed sensor is successfully integrated into a flow injection analysis (FIA) system to enable real-time and continuous iodide monitoring with high precision, high sample throughput and applicability for quality control of pharmaceuticals and environmental monitoring. Full article

This paper proposes a unified energy management, fault detection, and fault-tolerant control (EMS–FDI–FTC) framework for Hybrid Hydrogen Electric Vehicles (HHEVs) integrating a fuel cell (FC), battery (Bat), and supercapacitor (SC). While such multi-source architectures enable high-efficiency propulsion under dynamic driving conditions, actuator and state faults such as FC voltage sag, Bat internal resistance increase, and SC capacitance degradation can compromise safety, availability, and component lifetime. The proposed framework converts real-world GPS-recorded vehicle speed profiles into route-aware traction power demand and combines interpretable model-based indicators with an AI-based fault detection and classification module. Based on the diagnosis outcome, a fault-tolerant supervisory strategy performs online power reallocation among the FC, Bat, and SC while enforcing operational constraints. Validation is conducted in a MATLAB-based software-in-the-loop (SIL) environment using three urban driving routes collected from on-road measurements in Tunisia with injected ground-truth faults. The results demonstrate reliable fault classification performance and effective service continuity during fault intervals, supplying over 94% of the demanded energy across all routes, with energy-not-served remaining below 0.02 kWh. In addition, processor-in-the-loop (PIL) implementation on an STM32F407VG controller confirms real-time feasibility with a 10 Hz supervisory sampling rate and execution time margins compatible with embedded automotive deployment. Overall, the proposed closed-loop framework provides a practical route-aware diagnosis-to-control solution for robust and fault-resilient HHEV operation under realistic driving variability. All energy and efficiency indicators reported in this study are derived from control-oriented component models and are intended for consistent comparative evaluation across routes and operating scenarios, rather than absolute representation of a specific commercial vehicle. Full article

The performance and reliability of 4H-SiC Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) are largely determined by the material properties of gate dielectric films and the quality of the dielectric/SiC interface. This paper provides a systematic review of recent progress in gate dielectric engineering for 4H-SiC MOSFETs, with emphasis on SiO₂-based gate dielectrics and high-dielectric-constant (high-k) gate dielectrics. First, for conventional thermally grown SiO₂/SiC systems, the effects of interface nitridation, gate oxide doping, and surface pretreatment techniques are comprehensively discussed. The influence mechanisms of these processes on carbon-related interface defects, interface state density and field-effect mobility are analyzed, and the advances in related research are summarized. Second, the application of high-k gate dielectrics, including Al₂O₃, HfO₂, ZrO₂, and stacked dielectric structures, in SiC MOS devices is systematically reviewed. The advantages of these materials in reducing equivalent oxide thickness, increasing gate capacitance, suppressing leakage current, and improving thermal stability are highlighted. In addition, interface defects and electrical characteristics associated with different high-k gate dielectrics are comparatively evaluated. Finally, future research directions are discussed, including in situ interface engineering based on atomic layer deposition, dopant modulation, and heterogeneous gate dielectric structures. These approaches show strong potential for achieving high mobility, low loss, and high reliability in advanced 4H-SiC power MOSFETs. Full article

This article delineates the electrical characteristics and usefulness of a plasticized polymer electrolyte (PPE) manufactured from PVDF/PEO blends, using varying weight percentages of the plasticizer ethylene carbonate (EC) in conjunction with a liquid electrolyte. Micro-porous solid-state polymer electrolyte membranes were fabricated using the non-solvent-induced phase separation (NIPS) method. The polymer composite membranes modified by the incorporation of a plasticizer (40 weight percent of EC) exhibited enhanced porosity and absorbed a significant quantity of liquid electrolyte (313.3%). A N₂ adsorption isotherm study indicates an increase in pore volume and pore size resulting from the incorporation of EC in PPE. This resulted in a satisfactory level of ionic conductivity (2.08 mS/cm) at 25 °C, attributable to the inclusion of 40 wt.% EC-based PPE, which has a high dielectric constant and a rapid relaxation time. The AC/40 wt.% EC-based PPE/LTO hybrid supercapacitor exhibits a superior specific capacitance, reduced internal resistance, and enhanced retention values after 10,000 cycles in comparison to the AC/10 wt.% EC-based PPE/LTO hybrid supercapacitor. Full article

Accurate and in-situ monitoring of frost growth on plant leaves is crucial for disaster prevention in smart agriculture. To address the limitations of traditional methods in quantification and continuity, this study proposes a novel monitoring paradigm integrating dynamic dielectric spectrum analysis with hybrid intelligent algorithms. A mesh-electrode-based capacitive sensor was designed to capture in-situ and continuous dielectric spectrum changes on leaf surfaces. Subsequently, a hybrid SWT-SSA-LSTM model was constructed for high-fidelity denoising and prediction of the original signals. Field experiments demonstrated that this system could quantify frost layer mass and thickness with high precision. The established nonlinear regression models achieved coefficients of determination of 0.924 and 0.975, respectively. The prediction model exhibited outstanding performance, with a root mean square error as low as 1.475. This study establishes a complete technical closed-loop from physical perception to intelligent prediction, providing an innovative solution for precise frost monitoring in agriculture. Full article

Blood pressure (BP) monitoring is crucial for identifying high BP (hypertension) and is an important aspect of patient care. However, traditional cuff-based methods for BP monitoring are unsuitable for continuous monitoring and can cause discomfort to patients. This survey critically examines the emerging field of cuffless BP monitoring, highlighting advances beyond traditional cuff-based methods. Technologies such as radar, optical, acoustic, and capacitive sensors offer the potential for continuous, non-invasive BP estimation, enabling applications in remote health monitoring and ambient clinical intelligence. We introduce a unifying taxonomy covering sensing modalities, physiological measurement principles, signal processing techniques, and translational challenges. Emphasis is placed on methods that eliminate subject-specific calibration, overcome motion artifacts, and satisfy international validation standards. The review also analyses Machine Learning (ML) and sensor fusion approaches that enhance predictive accuracy. Despite encouraging results, challenges remain in achieving clinically acceptable accuracy across diverse populations and real-world conditions. This work delineates the current landscape, benchmarks performance against gold standards, and identifies key future directions for scalable, explainable, and regulatory-compliant BP monitoring systems. Full article

As a core functional component of multi-degree-of-freedom precision motion mechanisms, spherical hinges are widely used in high-end equipment fields such as industrial robots, vehicle engineering, and intelligent manufacturing. Their dynamic performance directly determines the motion accuracy and the level of intelligent control of the equipment. The high-precision real-time measurement of two-degree-of-freedom (2-DOF) angles is a key prerequisite for achieving precise closed-loop control of spherical hinges. However, due to the strong coupling characteristics between the 2-DOF angle signals, it is difficult to directly and accurately measure the angular motion parameters of spherical hinges, which has become a core technical bottleneck restricting the improvement in their application efficiency. To address this challenge, this paper presents an improved study of the previously proposed spherical differential quadrature capacitance sensor for measuring the 2-DOF angle signals of spherical hinges. Firstly, the 2-DOF angle signal decoupling model is reconstructed and optimized. Secondly, a real-time decoupling circuit architecture for phase-shift detection with single-frequency signal excitation is innovatively proposed. This solution effectively addresses the incomplete decoupling of 2-DOF angle signals in previous studies, as well as the problems of considerable measurement noise, low resolution, and high calibration difficulty caused by random amplitude and phase errors in the excitation signals. Through the construction of an experimental platform for verification tests, the results show that the proposed scheme can significantly suppress the random errors caused by the parameter dispersion of the device, achieve an angle measurement resolution of 0.001°, and simultaneously considerably reduce the complexity of system calibration, laying a key technical foundation for the engineering application of spherical hinges in the fields of precision measurement and high-performance control. Full article

This work presents a comprehensive quantum transport modeling and simulation framework to evaluate parasitic effects and radio frequency (RF) performance in stacked silicon (Si) nanosheet (NS) lateral gate-all-around (LGAA) nFETs targeting the sub-2 nm technology node. Leveraging the non-equilibrium Green’s function (NEGF) method, the proposed framework integrates detailed modeling of parasitic resistances (R_para) and capacitances (C_para) to enable a holistic analysis of both intrinsic and extrinsic figures-of-merit, including transconductance (g_m), output conductance (g_d), cutoff frequency (f_T), and maximum oscillation frequency (f_max). The effects of nanosheet geometry, crystal orientations, and dual-k spacers on high-frequency performance are systematically investigated. The analysis reveals key design trade-offs, with optimized device configurations yielding f_T exceeding 400 GHz and f_max approaching 1.2 THz. These findings highlight the potential of stacked NS LGAA-nFETs for future millimeter-wave and terahertz applications, providing critical insights into parasitics management and quantum-transport-aware design strategies at advanced CMOS nodes. Full article

This study investigates the electrical performance of two 4H-SiC p⁺-i-n⁻ diodes, based on lightly doped epitaxial layers, representative of high-voltage and neutron-detector structures. Each design was implemented in multiple nominally identical devices and characterized over the temperature range 298–623 K, with particular attention to the influence of p⁺ layer fabrication, n-type epitaxial layer thickness, and doping concentration. One diode features an ion-implanted p⁺ layer on a 250 µm thick n-type epitaxial layer, while the other employs an epitaxially grown p⁺ layer on a 100 µm thick n-type epitaxial layer. A comparison of reverse-bias Current–Voltage (I–V) and Capacitance–Voltage (C–V) characteristics indicates that, although both designs exhibit high-quality epitaxial 4H-SiC material, devices with an implanted p⁺ anode tend to show a more pronounced temperature-dependence and degradation of selected electrical parameters in reverse bias than those with an epitaxial p⁺ anode, while forward I–V in the range 298–623 K remains broadly similar for both designs. These observations suggest that anode fabrication and epitaxial design may jointly influence thermal stability, recombination mechanisms, and overall electrical performance, offering guidance for the optimization of 4H-SiC-based power and neutron-detector devices for high-temperature and harsh environments. Full article