Search Results (334)

To develop solutions to the frequency instability and failure of silicon micromechanical resonant accelerometers, the state characteristics of micromechanical resonant accelerometers are investigated under temperature and vibration stresses. Through theoretical analysis and finite element simulation, the following is found: the Young’s modulus of silicon varies with temperature, causing a resonance frequency shift of −1.364 Hz/°C; the residual stress of temperature change affects the resonance frequency shift of the microstructure, causing it to be 5.43 Hz/MPa (tensile stress) and −5.25 Hz/MPa (compressive stress); thermal expansion triggers the failure of the bonding wire, and, in the range of 10 °C to 150 °C, the peak stress of the electrode/lead bond area increases from 83.2/85.6 MPa to 1.08/1.28 GPa. The failure mode under vibration stress is resonance structure fracture and interlayer peeling. An isolation frame design is proposed for the sensitive part of the microstructure, which reduces the frequency effects by 34% (tensile stress) and 15% (compressive stress) under temperature-variable residual stresses and the maximum value of the structural root mean square stresses by 69.7% (X-direction), 63.6% (Y-direction), and 71.3% (Z-direction) under vibrational stresses. Full article

Silicon carbide (SiC) half-bridge power modules are widely utilized in new energy power generation, electric vehicles, and industrial power supplies. To address the research gap in collaborative validation between electro-thermal coupling models and process reliability, this paper proposes a closed-loop methodology of “design-simulation-process-validation”. This approach integrates in-depth electro-thermal simulation (LTspice XVII/COMSOL Multiphysics 6.3) with micro/nano-packaging processes (sintering/bonding). Firstly, a multifunctional double-pulse test board was designed for the dynamic characterization of SiC devices. LTspice simulations revealed the switching characteristics under an 800 V operating condition. Subsequently, a thermal simulation model was constructed in COMSOL to quantify the module junction temperature gradient (25 °C → 80 °C). Key process parameters affecting reliability were then quantified, including conductive adhesive sintering (S820-F680, 39.3 W/m·K), high-temperature baking at 175 °C, and aluminum wire bonding (15 mil wire diameter and 500 mW ultrasonic power/500 g bonding force). Finally, a double-pulse dynamic test platform was established to capture switching transient characteristics. Experimental results demonstrated the following: (1) The packaged module successfully passed the 800 V high-voltage validation. Measured drain current (4.62 A) exhibited an error of <0.65% compared to the simulated value (4.65 A). (2) The simulated junction temperature (80 °C) was significantly below the safety threshold (175 °C). (3) Microscopic examination using a Leica IVesta 3 microscope (55× magnification) confirmed the absence of voids at the sintering and bonding interfaces. (4) Frequency-dependent dynamic characterization revealed a 6 nH parasitic inductance via Ansys Q3D 2025 R1 simulation, with experimental validation at 8.3 nH through double-pulse testing. Thermal evaluations up to 200 kHz indicated 109 °C peak temperature (below 175 °C datasheet limit) and low switching losses. This work provides a critical process benchmark for the micro/nano-manufacturing of high-density SiC modules. Full article

In the present study, an L-shaped multi-walled structure of NiTi shape memory alloy (SMA) was fabricated by using the wire arc additive manufacturing (WAAM) method on a titanium substrate. The present study aims to investigate the fabricated structure for microstructure, macrostructure, and mechanical properties. The 40 layers of L-shaped structure were successfully fabricated at optimized parameters of wire feed speed at 6 m/min, travel speed at 12 mm/s, and voltage at 20 V. The macrographs demonstrated the continuous bonding among the layers with complete fusion. The microstructure in the area between the two middle layers has exhibited a mixture of columnar grains (both coarse and fine), interspersed with dendritic colonies. The microstructure in the topmost layers has exhibited finer colonial structures in relatively greater numbers. The microhardness (MH) test has shown the average values of 283.2 ± 3.67 HV and 371.1 ± 5.81 HV at the bottom and topmost layers, respectively. A tensile test was conducted for specimens extracted from deposition and build directions, which showed consistent mechanical behavior. For the deposition direction, the average ultimate tensile strength (UTS) and elongation (EL) were obtained as 831 ± 22.91 MPa and 14.32 ± 0.55%, respectively, while the build direction has shown average UTS and EL values of 774 ± 6.56 MPa and 14.16 ± 0.21%, respectively. The elongation exceeding 10% in all samples suggests that the fabricated structure demonstrates properties comparable to those of wrought metal. Fractography of all tensile specimens has shown good ductility and toughness. Lastly, a differential scanning calorimetry test was carried out to assess the retention of shape memory effect for the fabricated structure. The authors believe that the findings of this work will be valuable for various industrial applications. Full article

Reducing structural mass and volume is critical to improving efficiency and payload capacity in next-generation small satellites and CubeSats. Additive manufacturing, particularly material extrusion, offers design flexibility and enables the production of lightweight, functional metallic components. This study investigates the integration of nickel–titanium shape memory alloy wires into aluminum-based matrices using a sinter-based material extrusion process, aiming to develop compact actuator systems for aerospace applications. A customized AlSi7Mg aluminum alloy feedstock was extruded into filament form, printed, and embedded with shape memory alloy wires, allowing consolidation during sintering. X-ray micro-computed tomography was used to analyze internal defects and matrix–wire interfacial contact, before and after sintering. Tensile testing of the embedded actuator structures revealed effective mechanical bonding and actuation behavior. The results demonstrate that controlled shrinkage and interfacial bonding enable reliable embedding of shape memory elements without compromising structural integrity. This work provides a promising framework for developing multifunctional aerospace components, where active actuation and structural efficiency can be combined through advanced material extrusion-based manufacturing. Full article

Touch is a crucial sense for advanced organisms, particularly humans, as it provides essential information about the shape, size, and texture of contacting objects. In robotics and automation, the integration of tactile sensors has become increasingly relevant, enabling devices to properly interact with their environment. This study aimed to develop a biomimetic, skin-inspired tactile sensor device capable of sensing applied force, characterizing it in three dimensions, and determining the point of application. The device was designed as a 4 × 4 matrix of tunneling magnetoresistive sensors, which provide a higher sensitivity in comparison to the ones based on the Hall effect, the current standard in tactile sensors. These detect magnetic field changes along a single axis, wire-bonded to a PCB and encapsulated in epoxy. This sensing array detects the magnetic field from an overlayed magnetorheological elastomer composed of Ecoflex and 5 µm neodymium–iron–boron ferromagnetic particles. Structural integrity tests showed that the device could withstand forces above 100 N, with an epoxy coverage of 0.12 mL per sensor chip. A 3D movement stage equipped with an indenting tip and force sensor was used to collect device data, which was then used to train neural network models to predict the contact location and 3D magnitude of the applied force. The magnitude-sensing model was trained on 31,260 data points, being able to accurately characterize force with a mean absolute error ranging between 0.07 and 0.17 N. The spatial sensitivity model was trained on 171,008 points and achieved a mean absolute error of 0.26 mm when predicting the location of applied force within a sensitive area of 25.5 mm × 25.5 mm using sensors spaced 4.5 mm apart. For points outside the testing range, the mean absolute error was 0.63 mm. Full article

Over the last two decades, the use of photovoltaic panels for the production of electricity has increased significantly, which leads to the need to solve the problems concerning the decommissioning and disposal of the panels and the development of appropriate technologies for their recycling. One of the key steps in this process is the separation of the tempered glass layer. Various technologies and devices are known for separating the glass of the solar panel by cutting it with a knife, as well as other instruments, with the different methods being based on mechanical, chemical, and thermal processes and accordingly having their own advantages and disadvantages. This article proposes an innovative approach for the mechanical delamination of solar panels using a metal wire heated by Joule heating, with the potential to become an energy-efficient, economical, and environmentally friendly method. This publication presents results from experiments using this type of tool to separate the layers of solar panels. Photos from a thermal camera are presented, showing the heat distribution in the panel and the reached operating temperature of the heated metal wire, necessary to soften the EVA bonding layer. Full article

Artificial retinal devices require a high-density electrode array and mechanical flexibility to effectively stimulate retinal cells. However, designing such devices presents significant challenges, including the need to conform to the curvature of the eyeball and cover a large area using a single platform. To address these issues, we developed a parylene-based multi-module retinal device (MMRD) integrating a complementary metal-oxide semiconductor (CMOS) system. The proposed device is designed for suprachoroidal transretinal stimulation, with each module comprising a parylene-C thin-film substrate, a CMOS chip, and a ceramic substrate housing seven platinum electrodes. The smart CMOS system significantly reduces wiring complexity, enhancing the device’s practicality. To improve fabrication reliability, we optimized the encapsulation process, introduced multiple silane coupling modifications, and utilized polyvinyl alcohol (PVA) for easier detachment in flip-chip bonding. This study demonstrates the fabrication and evaluation of the MMRD through in vitro and in vivo experiments. The device successfully generated the expected current stimulation waveforms in both settings, highlighting its potential as a promising candidate for future artificial vision applications. Full article

This paper extends the quasi-load insensitive (QLI) Class-E Doherty power amplifier (PA) design methodology to address Doherty PA combiners with complex load impedance trajectories. Additionally, the QLI operation is analyzed for generalized class-E output matching networks with input series inductors and finite DC-feed inductors. We demonstrate that the QLI class-E Doherty operation can be achieved for various Doherty combiners by selecting the appropriate combination of class-E outputs matching network resonance factors and input series inductances. Moreover, a modified class-E output network is proposed to overcome the frequency limitation that might be caused by the class-E network resonance factor choice. To validate the proposed methodology, two 40 W Doherty PAs are designed and simulated using commercial GaN HEMT transistors achieving more than 70% efficiency over a 6 dB output power back-off at 3.8 GHz. Full article

This study investigates the impact of modeling the aluminum (Al) metallization layer as an integrated part of the chip model, versus as an individual component, on the results of electrical–thermal analysis of power semiconductor packages using Finite Element Analysis (FEA), ANSYS 2024 R2. The results showed that modeling the aluminum metallization layer separately exhibited high consistency with actual thermal imaging data. Furthermore, based on these findings, we observed through simulations that the aluminum metallization layer plays a key role in improving the uniformity of current density and temperature distribution within the chip. Using the aluminum metallization layer model, we optimized the thickness, material, and design of the metallization layer, as well as the bonding wire material through the design of experiments (DOE) methodology. Under the optimized conditions, an optimal design is proposed to minimize the voltage–current ratio (V_DS/I_DS), maximum junction temperature, strain, and von Mises stress. This study systematically examines the influence of aluminum metallization layer modeling on FEA-based power semiconductor package simulations and is expected to serve as a valuable reference for future power device design utilizing finite element analysis. Full article

This study experimentally and numerically investigated the effectiveness of fiber-core steel wire ropes (FC-SWRs) in enhancing the flexural performance of reinforced concrete (RC) T-beams using a bonding technique. The investigation focused on deflection, flexural load-carrying capacity, and failure modes, along with key behaviors such as ductility, stiffness, energy absorption, and steel strain response. Two beams were tested under four-point bending until failure—one serving as the control specimen and the other strengthened with bonded FC-SWRs to improve its flexural behavior. Additionally, an analytical study was conducted using a computer program based on the Modified Compression Field Theory (MCFT), and the results were compared with experimental findings. The validation of the analytical model enabled further parametric investigations, examining the influence of the FC-SWR diameter, modulus of elasticity, and steel reinforcement ratio on flexural performance. Full article

Electronic packaging can transform the chip to a device for assembly. Soldering and bonding are important procedures in the process of electronic packaging. The continuous development of packaging architecture has driven the emergence of improved soldering and bonding processes. At the same time, conventional soldering and bonding processes are still widely used in device packaging. This paper introduces two kinds of technologies in wafer bonding, direct and indirect, expounds on five kinds of die attachment processes, and also describes the process of ball bonding and wedge bonding in wire bonding in detail. Flip chip bonding and methods for making bumps are also described in depth. Bump bonding processes are vital for 3D-SiP packages, and the bonding technology of copper bumps is a research hotspot in the field of advanced packaging. The surface mount technology and sealing technology used in some electronic devices are also briefly introduced. This paper provides insights for researchers studying soldering and bonding in contemporary electronic device packaging. Full article

A solid/liquid continuous composite casting technology was developed to produce brass-clad copper stranded wire billets efficiently with continuous casting speeds ranging from 200 mm/min to 1000 mm/min. As the casting speed increased, the microstructure of the brass cladding transformed at an angle to the radial direction. The wire billet prepared at a casting speed of 600 mm/min was then subjected to drawing. As the percentage reduction in area of the billet increased from 11.9 to 81.5% during the drawing process, the tensile strength improved from 336 MPa to 534 MPa, while the elongation after fracture decreased from 30.1 to 4.7%. Meanwhile, dislocation, dislocation cells, and microbands successively formed in the pure copper strand wires, while twins, shear bands, dislocation pile-ups, and secondary twins gradually formed in the brass cladding. During the drawing process, the interface between copper and brass remained metallurgically bonded, exhibiting coordinated deformation behavior. This paper clarified the evolution of microstructure and mechanical properties of brass-clad copper stranded wires in high-speed solid/liquid continuous composite casting and drawing, which could provide important reference for industrial production. Full article

This study elucidates the structural determinants and optogenetic potential of Archaerhodopsin HeAR, a proton pump from Halorubrum sp. Ejinoor isolated from Inner Mongolian salt lakes. Through heterologous expression in E. coli BL21 (DE3) and integrative biophysical analyses, we demonstrate that HeAR adopts a stable trimeric architecture (129 kDa) with detergent-binding characteristics mirroring bacteriorhodopsin (BR); however, it exhibits a 10 nm bathochromic spectral shift (λmax = 550 nm) and elevated proton affinity (Asp-95 pKa = 3.5 vs. BR Asp-85 pKa = 2.6), indicative of evolutionary optimization in its retinal-binding electrostatic microenvironment. Kinetic profiling reveals HeAR’s prolonged photocycle (100 ms vs. BR’s 11 ms), marked by rapid M-state decay (3.3 ms) and extended dark-adaptation half-life (160 min), a bistable behavior attributed to enhanced hydrogen bond persistence (80%) and reduced conformational entropy (RMSD = 2.0 Å). Functional assays confirm light-driven proton extrusion (0.1 ng H⁺/mg·s) with DCCD-amplified flux (0.3 ng H⁺/mg·s) and ATP synthesis (0.3 nmol/mg·s), underscoring its synergy with H⁺-ATPase. Phylogenetic and structural analyses reveal 95% homology with Halorubrum AR4 and conservation of 11 proton-wire residues, despite divergent Trp/Tyr/Ser networks that redefine chromophore stabilization. AlphaFold-predicted models (TM-score > 0.92) and molecular docking identify superior retinoid-binding affinity (ΔG = −12.27 kcal/mol), while spectral specificity (550–560 nm) and acid-stable photoresponse highlight its adaptability for low-irradiance neuromodulation. These findings position HeAR as a precision optogenetic tool, circumventing spectral overlap with excitatory opsins and enabling sustained hyperpolarization with minimized phototoxicity. By bridging microbial energetics and optobioengineering, this work expands the archaeal rhodopsin toolkit and provides a blueprint for designing wavelength-optimized photoregulatory systems. Full article

In recent years, there has been a growing interest in and research efforts enabling the use of composite conductive 3D-printing filaments in material extrusion additive manufacturing processes, which can bestow novel and distinctive functions onto 3D-printed components. These composite filaments, in general blending a thermoplastic with carbon-based materials, open up new research and development avenues in electronics and sensors. Additionally, by exploring the underlying piezoresistivity of conductive filaments, they also enable the creation of novel structural components possessing integrated (intrinsic) self-sensing capabilities that can be effectively employed in structural health monitoring of critical components. However, piezoresistivity features require measuring the electrical resistance of structures made with these conductive filaments, which might be hard, especially when measuring small changes in resistance caused by mechanical loads on the component. The goal of this study is to compare the two- and four-probe methods for measuring the electrical resistance of 3D-printed parts and to look at how different types of electrical contacts and bonding may affect electrical resistivity measurement and self-sensing capabilities. The research is conducted on 3D-printed specimens using a conductive composite PLA (polylactic acid) filament from Protopasta. The efficiency of each method and the influence of the bonding and electrodes on the measurements are experimentally analyzed and discussed. Our experiments reveal that the four-probe method consistently yields resistivity values between 15.35 and 16.38 $\mathrm{\Omega }·$cm, while the two-probe method produces significantly higher values (up to 52.92–62.37 $\mathrm{\Omega }·$cm), underscoring the impact of wire and contact resistances on measurement accuracy. Full article

Strengthening lapped spliced reinforced concrete (RC) beams using tiny-diameter steel wires as near-surface-mounted (NSM) rods has not been carried out previously. Thus, the purpose of this work is to examine the behavior of RC beams with insufficient lap splices that are strengthened by NSM steel wires with different schemes to improve durability, efficiency, and effectiveness. At the middle of the beam, a splice length equal to 25 times the diameter of the rebar was used to join two tension bars. Many different schemes were implemented in strengthening the splice region, such as attaching longitudinal wires to the sides and/or bottom of the beam in different quantities with/without end anchorage, placing perpendicular and inclined U-shaped wires at the splice region in different quantities, and implementing a network of intersecting and opposite wires in two different directions. The effect of variables on the behavior of strengthened beams was studied. The findings proved that when the longitudinal wire reinforcement-to-lapped rebars area ratio was 9.4%, 18.7%, and 28%, the ultimate load of the beams was improved by 15.71%, 71.43%, and 104.57%, respectively. When the transverse U-shaped wire reinforcement ratio was 0.036, 0.051, 0.064, 0.075, and 0.150, the ultimate load of the beams was improved by 3.7%, 20%, 31.4%, 50%, and 80%, respectively, and the ultimate deflection was enhanced by 2%, 32%, 19%, 67%, and 62.4% compared to the unstrengthened beam. Full article