Search Results (543)

This paper presents a novel approach employing localized annealing through Joule heating to enhance the performance of Thin-Film Piezoelectric-on-Silicon (TPoS) MEMS resonators that are crucial for applications in sensing, energy harvesting, frequency filtering, and timing control. Despite recent advancements, piezoelectric MEMS resonators still suffer from anchor-related energy losses and limited quality factors (Qs), posing significant challenges for high-performance applications. This study investigates interface modification to boost the quality factor (Q) and reduce the motional resistance, thus improving the electromechanical coupling coefficient and reducing insertion loss. To balance the trade-off between device miniaturization and performance, this work uniquely applies DC current-induced localized annealing to TPoS MEMS resonators, facilitating metal diffusion at the interface. This process results in the formation of platinum silicide, modifying the resonator’s stiffness and density, consequently enhancing the acoustic velocity and mitigating the side-supporting anchor-related energy dissipations. Experimental results demonstrate a Q-factor enhancement of over 300% (from 916 to 3632) and a reduction in insertion loss by more than 14 dB, underscoring the efficacy of this method for reducing anchor-related dissipations due to the highest annealing temperature at the anchors. The findings not only confirm the feasibility of Joule heating for interface modifications in MEMS resonators but also set a foundation for advancements of this post-fabrication thermal treatment technology. Full article

Selective laser melting (SLM) offers a novel approach for manufacturing intricate structures, broadening the application of titanium alloy parts in the aerospace industry. After the build period, heat treatments of annealing (AT) and hot isostatic pressing (HIP) are often implemented, but a comparison of their mechanical performances based on the specimen orientation is still lacking. In this study, horizontally and vertically built Ti6Al4V SLM specimens that underwent the aforementioned treatments, together with their microstructural and defect characteristics, were, respectively, investigated using metallography and X-ray imaging. The mechanical properties and failure mechanism, via fracture analysis, were obtained. The critical factors influencing the mechanical properties and the correlation of the fatigue lives and failure origins were also estimated. The results demonstrate that the mechanical performances were determined by the α-phase morphology and defects, which included micropores and fewer large lack-of-fusion defects. Following the coarsening of the α phase, the strength decreased while the plasticity remained stable. With the discrepancy in the defect occurrence, anisotropy and scatter of the mechanical performances were introduced, which was significantly alleviated with HIP treatment. The fatigue failure origins were governed by defects and the α colony, which was composed of parallel α phases. Approximately linear relationships correlating fatigue lives with the X-parameter and maximum stress amplitude were, respectively, established in the AT and HIP states. The results provide an understanding of the technological significance of the evaluation of mechanical properties. Full article

Background/Objectives: The work presented herein focused on the development and characterization of a transdermal caffeine platform fabricated from ultrathin micro- and submicron fibers produced via electrospinning. Methods: The formulations incorporated caffeine encapsulated in a polyethylene oxide (PEO) matrix, combined with various permeation enhancers. A backing layer made of annealed electrospun polycaprolactone (PCL) facilitated the lamination of the two layers to form the final multilayer patch. Comprehensive characterization was conducted, utilizing scanning electron microscopy (SEM) to assess the fiber morphology, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) for chemical detection and to assess the stability of the caffeine, and differential scanning calorimetry (DSC) along with wide-angle X-ray scattering (WAXS) to analyze the physical state of the caffeine within the fibers of the active layer. Additionally, Franz cell permeation studies were performed using both synthetic membranes (Strat-M) and ex vivo human stratum corneum (SC) to evaluate and model the permeation kinetics. Results: These experiments demonstrated the significant role of enhancers in modulating the caffeine permeation rates provided by the patch, achieving permeation rates of up to 0.73 mg/cm² within 24 h. Conclusions: This work highlights the potential of using electro-hydrodynamic processing technology to develop innovative transdermal delivery systems for drugs, offering a promising strategy for enhancing efficacy and innovative therapeutic direct plasma administration. Full article

Recently, with the development of automation technology in various fields, much research has been conducted on infrared photodetectors, which are the core technology of LiDAR sensors. However, most infrared photodetectors are expensive because they use compound semiconductors based on epitaxial processes, and they have low safety because they use the near-infrared (NIR) region that can damage the retina. Therefore, they are difficult to apply to automation technologies such as automobiles and factories where humans can be constantly exposed. In contrast, short-wavelength infrared photodetectors based on PbS QDs are actively being developed because they can absorb infrared rays in the eye-safe region by controlling the particle size of QDs and can be easily and inexpensively manufactured through a solution process. However, PbS QDs-based SWIR photodetectors have low chemical stability due to the electron/hole extraction layer processed by the solution process, making it difficult to manufacture them in the form of patterning and arrays. In this study, bulk NiO and ZnO were deposited by sputtering to achieve uniformity and patterning of thin films, and the performance of PbS QDs-based photodetectors was improved by optimizing the thickness and annealing conditions of the thin films. The fabricated photodetector achieved a high response characteristic of 114.3% through optimized band gap and improved transmittance characteristics. Full article

Aluminum and its alloy magnetron sputtering targets, owing to their superior electrical/thermal conductivity and robust substrate adhesion, serve as critical materials in advanced electronics and information technologies. It is known that the microstructure of the target, including grain uniformity and crystallographic texture, directly affects the sputtering performance and the quality of the deposited thin film. Despite extensive research efforts, the review paper focused on the microstructure of aluminum target materials is still absent. In that context, the recent progress on the Al alloy target is reviewed, focusing on grain refinement and texture control strategies. The roles of alloying elements, such as Si, Cu, and rare-earth Sc and Nd, are described first. The two conventional manufacturing techniques of fabricating Al targets, including melting and powder metallurgy, are introduced. Then, studies on grain refinement by thermomechanical processing routes (hot/cold rolling, annealing and forging) are summarized. Lastly, texture engineering through deformation and heat treatment protocols (unidirectional/multidirectional rolling, deformation thickness, and composite deformation modes) is reviewed. By establishing the relationship between thermomechanical processing and microstructure, this review provides insights for designing high-performance aluminum targets tailored to next-generation advanced thin-film applications. Full article

High-Bandwidth Memory (HBM) enables the bandwidth required by modern AI and high-performance computing, yet its three dimensional stack traps heat and amplifies thermo mechanical stress. We first review how conventional solutions such as heat spreaders, microchannels, high density Through-Silicon Vias (TSVs), and Mass Reflow Molded Underfill (MR MUF) underfills lower but do not eliminate the internal thermal resistance that rises sharply beyond 12layer stacks. We then synthesize recent hybrid bonding studies, showing that an optimized Cu pad density, interface characteristic, and mechanical treatments can cut junction-to-junction thermal resistance by between 22.8% and 47%, raise vertical thermal conductivity by up to three times, and shrink the stack height by more than 15%. A meta-analysis identifies design thresholds such as at least 20% Cu coverage that balances heat flow, interfacial stress, and reliability. The review next traces the chain from Coefficient of Thermal Expansion (CTE) mismatch to Cu protrusion, delamination, and warpage and classifies mitigation strategies into (i) material selection including SiCN dielectrics, nano twinned Cu, and polymer composites, (ii) process technologies such as sub-200 °C plasma-activated bonding and Chemical Mechanical Polishing (CMP) anneal co-optimization, and (iii) the structural design, including staggered stack and filleted corners. Integrating these levers suppresses stress hotspots and extends fatigue life in more than 16layer stacks. Finally, we outline a research roadmap combining a multiscale simulation with high layer prototyping to co-optimize thermal, mechanical, and electrical metrics for next-generation 20-layer HBM. Full article

This review article provides an in-depth analysis of recent advancements in the fabrication, structural characterization, and magnetic properties of Heusler alloy glass-coated microwires, focusing on Co₂FeSi alloys. These microwires exhibit unique thermal stability, high Curie temperatures, and tunable magnetic properties, making them suitable for a wide range of applications in spintronics, magnetic sensing, and biomedical engineering. The review emphasizes the influence of geometric parameters, annealing conditions, and compositional variations on the microstructure and magnetic behavior of these materials. Detailed discussions on the Taylor–Ulitovsky fabrication technique, X-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM) provide insights into the structural properties of the microwires. The magnetic properties, including room-temperature behavior, temperature dependence, and the effects of annealing, are thoroughly examined. The potential applications of these microwires in advanced spintronic devices, magnetic sensors, and biomedical technologies are explored. The review concludes with future research directions, highlighting the potential for further advancements in the field of Heusler alloy microwires. Full article

Taguchi and post-heat treatment methods have been used in this study to optimize the metal inert gas (MIG) welding joints between SUS304 austenite stainless steel and plain carbon SS400 steel using AWS ER 308L filler wire. The dissimilar welding joints’ microstructure and tensile strength have been examined. The findings show that the fast cooling of the weld joint and the ferrite-forming element of the filler wire cause the dendrites’ δ-ferrite phase to emerge on both the weld bead and the heat-affected zone (HAZ) of the SUS304 side. The stickout parameter has the largest impact on the ultimate tensile strength (UTS), next to the welding speed, welding voltage, and welding current, due to the strong impact of the heat distribution. The optimal welding parameters are a welding current of 105 A, a welding voltage of 14.5 V, a stickout of 12 mm, and a welding speed of 420 mm/min, producing the UTS value of 445.3 MPa, which is close to the predicted value of 469.2 ± 53.6 MPa. Post-heat treatment with an annealing temperature that is lower than 700 °C could improve the optimized weld joints’ strength by up to 5%. The findings may provide a more realistic understanding of the dissimilar welding technology. Full article

In this study, phosphogypsum waste collected from a factory dump in Kedainiai, Lithuania, was used for the first time as a starting material in the dissolution–precipitation synthesis of high-quality bioceramic calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂; CHA). The CHA powders were synthesized using the dissolution–precipitation method, employing phosphogypsum in four different conditions: untreated, dried at 100 °C, dried at 150 °C, and annealed at 1000 °C. Various phosphorus sources were used in the CHA synthesis process: Na₂HPO₄; a mixture of Na₂HPO₄ and NaH₂PO₄; or a combination of Na₂HPO₄, NaH₂PO₄, and NaHCO₃. These mixtures were allowed to react at 80 °C for 48 h, 96 h, 144 h, and 192 h. X-ray diffraction (XRD) analysis revealed slight variations in the synthesized products depending on the specific starting materials used. Fourier transform infrared spectroscopy (FTIR) was conducted to confirm the structural characteristics of the synthesized CHA samples. The surface microstructure of the synthesized CHA samples differed notably from that of the raw phosphogypsum. All synthesized CHA samples exhibited Type IV nitrogen adsorption–desorption isotherms with H3-type hysteresis loops, indicating the presence of mesoporous structures, typically associated with slit-like pores or aggregates of plate-like particles. To the best of our knowledge, an almost monophasic CHA has been fabricated from phosphogypsum waste for the first time using a newly developed dissolution–precipitation synthesis method. A key challenge in the high-end market is the development of alternative synthesis technologies that are not only more environmentally friendly but also highly efficient. These findings demonstrate that phosphogypsum is a viable and sustainable raw material for CHA synthesis, with promising applications in the medical field, including the production of artificial bone implants. Full article

Personal Voice Activity Detection (PVAD) has emerged as a critical technology for enabling speaker-specific detection in multi-speaker environments, surpassing the limitations of conventional Voice Activity Detection (VAD) systems that merely distinguish speech from non-speech. PVAD systems are essential for applications such as personalized voice assistants and robust speech recognition, where accurately identifying a target speaker’s voice amidst background speech and noise is crucial for both user experience and computational efficiency. Despite significant progress, PVAD frameworks still face challenges related to temporal modeling, integration of speaker information, class imbalance, and deployment on resource-constrained devices. In this study, we present a systematic enhancement of the PVAD framework through four key innovations: (1) a Bi-GRU (Bidirectional Gated Recurrent Unit) layer for improved temporal modeling of speech dynamics, (2) a cross-attention mechanism for context-aware speaker embedding integration, (3) a hybrid CE-AUROC (Cross-Entropy and Area Under Receiver Operating Characteristic) loss function to address class imbalance, and (4) Cosine Annealing Learning Rate (CALR) for optimized training convergence. Evaluated on LibriSpeech datasets under varied acoustic conditions, the proposed modifications demonstrate significant performance gains over the baseline PVAD framework, achieving 87.59% accuracy (vs. 86.18%) and 0.9481 mean Average Precision (vs. 0.9378) while maintaining real-time processing capabilities. These advancements address critical challenges in PVAD deployment, including robustness to noisy environments, with the hybrid loss function reducing false negatives by 12% in imbalanced scenarios. The work provides practical insights for implementing personalized voice interfaces on resource-constrained devices. Future extensions will explore quantized inference and multi-modal sensor fusion to further bridge the gap between laboratory performance and real-world deployment requirements. Full article

Electrolytic copper foil is one of the core materials in the fields of electronics, communications, and power. The cathode roller is the key component of the complete set of electrolytic copper foil equipment, and the quality of the titanium cylinder of the cathode roller directly determines the quality of the electrolytic copper foil. There typically exists a longitudinal weld on the surface of the cathode roller’s titanium cylinder sleeve manufactured by the welding method, which leads to the degradation of the quality of the electrolytic copper foil. Refining the grains in the weld zone and the heat-affected zone to close to those of the base material is a key solution for the manufacturing of welded cathode rollers. In order to effectively modify the microstructure and obtain an optimal refining effect in the weld zone of a TA1 cathode roller, a novel composite technology consisting of low-energy and fewer-pass welding combined with multi-pass rolling deformation and vacuum annealing treatment was primarily explored for high-purity TA1 titanium plates in this study. The microstructure of each area of the weld was observed using the DMI-3000M optical microscope, and the hardness was measured using the HVS-30 Vickers hardness tester. The research results show that the microstructure of each area of the weld can be effectively refined by using the novel composite technology of low-energy and fewer-pass welding, multi-pass rolling deformation, and vacuum annealing treatment. Among the explored experimental conditions, the optimal grain refinement effect is obtained with a V-shaped welding groove and four passes of welding with a welding current of 90 A and a voltage of 8–9 V, followed by 11 passes of rolling deformation with a total deformation rate of 45% and, finally, vacuum annealing at 650 °C for 1 h. The grain size grades in the weld zone and the heat-affected zone are close to those of the base material, namely grade 7.5~10, grade 7.5~10, and grade 7.5~10 for the weld zone, heat-affected zone, and base material, respectively. Meanwhile, this technology can also refine the grains of the base material, which is conducive to improving the overall mechanical properties of the titanium plate. Full article

Transition metal dichalcogenides, especially molybdenum disulfide (MoS₂), exhibit exceptional properties that make them suitable for a wide range of applications. However, the interaction between MoS₂ and technologically relevant substrates, such as platinum (Pt) electrodes, can significantly influence its properties. This study investigates the growth and properties of MoS₂ thin films on Pt substrates using ionized jet deposition, a versatile, low-cost vacuum deposition technique. We explore the effects of the roughness of Pt substrates and self-heating during deposition on the chemical composition, structure, and strain of MoS₂ films. By optimizing the deposition system to achieve crystalline MoS₂ at room temperature, we compare as-deposited and annealed films. The results reveal that as-deposited MoS₂ films are initially amorphous and conform to the Pt substrate roughness, but crystalline growth is reached when the sample holder is sufficiently heated by the plasma. Further post-annealing at 270 °C enhances crystallinity and reduces sulfur-related defects. We also identify a change in the MoS₂–Pt interface properties, with a reduction in Pt–S interactions after annealing. Our findings contribute to the understanding of MoS₂ growth on Pt and provide insights for optimizing MoS₂-based devices in catalysis and electronics. Full article

With the evolution of synchrotron light sources to fourth generation (diffraction-limited storage rings), the brilliance is increased by several orders of magnitude compared to third generation facilities. For example, the Swiss Light Source (SLS) has been upgraded to SLS 2.0, promising a horizontal emittance reduced by a factor of 40, and a brilliance up to two orders of magnitude (three at higher energies). A key challenge arising from the increased flux is the heightened accumulated dose in silicon sensors, which leads to a significant increase in radiation damage. This translates into an increase of both noise and dark current, as well as a reduction in the dynamic range for long exposure times, thus affecting the performance of the detector, in particular, for charge-integrating detectors. We have designed sensors with a 4 × 4 mm² pixel array featuring 16 design variations of 25 µm pitch pixels with different implant and metal sizes and tested them bump-bonded to MÖNCH 0.3, a charge integrating hybrid pixel detector readout ASIC. Following a first assessment of the functionality and performance of the different pixel designs, the assembly has been irradiated with X-rays. The variation in the tested parameters was characterized at different accumulated doses up to 100 kGy at the sensor entrance window side. The annealing dynamics at room temperature have also been measured. The results show that the default pixel design is currently not optimal and can benefit from layout changes (reduction in the inter-pixel gap area with full metal coverage of the implant). Further studies on the metal coverage over large implants could be conducted. The layout changes are, however, not sufficient for future full-sized sensors, requiring improved radiation hardness and long-term stability, and additional strategies such as focusing on detector cooling and changes in sensor technologies would be required. Full article

High-performance flexible sensors capable of direct integration with biological tissues are essential for personalized health monitoring, assistive rehabilitation, and human–machine interaction. However, conventional devices face significant challenges in achieving conformal integration with biological surfaces, along with sufficient biomechanical compatibility and biocompatibility. This research presents an in situ 3D biomanufacturing strategy utilizing Direct Ink Writing (DIW) technology to fabricate functional bioelectronic interfaces directly onto human skin, based on a novel annealing PEDOT:PSS/PVA composite bio-ink. Central to this strategy is the utilization of a novel annealing PEDOT:PSS/PVA composite material, subjected to specialized processing involving freeze-drying and subsequent thermal annealing, which is then formulated into a DIW ink exhibiting excellent printability. Owing to the enhanced network structure resulting from this unique fabrication process, films derived from this composite material exhibit favorable electrical conductivity (ca. 6 S/m in the dry state and 2 S/m when swollen) and excellent mechanical stretchability (maximum strain reaching 170%). The material also demonstrates good adhesion to biological interfaces and high-fidelity printability. Devices fabricated using this material achieved good conformal integration onto a finger joint and demonstrated strain-sensitive, repeatable responses during joint flexion and extension, capable of effectively transducing local strain into real-time electrical resistance signals. This study validates the feasibility of using the DIW biomanufacturing technique with this novel material for the direct on-body fabrication of functional sensors. It offers new material and manufacturing paradigms for developing highly customized and seamlessly integrated bioelectronic devices. Full article

A new brazing process for thin-walled stainless steel was proposed by combining green and efficient Ni-Cr-P electrodeposition with brazing technology. Novel information was attained by analyzing the electrodeposited Ni-Cr-P interlayers and the brazed joints and characterizing them using a combination of advanced techniques. The incorporation mechanisms of impurities (i.e., oxygen and carbon) in the Ni-Cr-P interlayers electrodeposited from a Cr(III)–glycine solution were revealed. The oxygen mainly came from the Cr(III)–hydroxy complexes formed by the hydrolysis and olation between Cr(III) complexes and OH⁻ ions near the cathode. Glycine did not directly participate in the cathode reactions but decomposed on the anode surface. These byproducts (carbonyl compounds) were directly incorporated into the interlayers in a molecular pattern, forming a weak link to the metallic chromium. Brazing test results showed that a certain amount of Cr₂O₃ powder, formed by the decomposition of chromium hydroxides in the interlayers under high-temperature catalysis, would cause the degradation of the brazed joints. Using the step-wise brazing method, the brazing sheets were first annealed to eliminate the impurities by utilizing the strong reducing effect of hydrogen and the weak link characteristics between carbonyl compounds and metallic chromium atoms. An excellent joint with a shear strength of 63.0 MPa was obtained by subsequent brazing. The microstructural analysis showed that the brazed seam was mainly composed of a Ni-Fe-Cr solid solution, the Ni₃P eutectic phase, and small quantities of the Ni₅P₂ phase scattered in the Ni₃P eutectic phase. Fracture mode observations showed that the cracks extended along the interface between the brittle P-containing phase and the primary phase, resulting in fracture. Full article