Micromachines最新文献

The Journal retracts the article titled "Delineating Conformational Variability in Small Protein Structures Using Combinatorial Refinement Strategies" [...].

Sub-resolution assist feature (SRAF) is a widely used resolution enhancement technology for improving image contrast and the common process window in advanced lithography processes. However, both model-based SRAF and rule-based SRAF methods suffer from challenges of adaptability or high computational cost. The primary learning-based SRAF method adopts an end-to-end mode, treating the entire mask pattern as a pixel map, and it is difficult to obtain precise geometric parameters for the commonly used Manhattan SRAFs. This paper proposes a two-stage Unet framework to effectively predict the centroid coordinates and dimensions of SRAF polygons. Furthermore, an adaptive hybrid attention mechanism is introduced to dynamically integrate global and local features, thus enhancing the prediction accuracy. Additionally, a warm-up cosine annealing learning rate strategy is adopted to improve the training stability and convergence speed. Simulation results demonstrate that the proposed method accurately and rapidly estimates the SRAF parameters. Compared to traditional neural networks, the proposed method can better predict SRAF patterns, with the mean pattern error and edge placement error values showing the most significant reductions. PE decreases from 25,776.44 to 15,203.33 and EPE from 5.8367 to 3.5283, respectively. This significantly improves the image fidelity of the lithography system.

Ba_0.6Sr_0.4TiO₃ (BST) thin films were deposited on ITO substrates via rf magnetron sputtering, followed by structural and morphological characterization using XRD and FE-SEM. Metal-insulator-metal (MIM) RRAM devices were fabricated by depositing Al top electrodes, and their electrical properties were examined through I-V measurements. The optimized BST films deposited at 40% oxygen concentration exhibited stable resistive switching, with an operating voltage of 3 V, an on/off ratio of 1, and a leakage current of 10^-8 A. After rapid thermal annealing at 500 °C, the on/off ratio improved to 2 but leakage increased to 10^-3 A. Incorporating an electron transport layer (ETL) effectively suppressed the leakage current to 10^-5 A while maintaining the on/off ratio at 2. Moreover, a transition from bipolar to unipolar switching was observed at higher oxygen concentration (60%). These results highlight the role of ETLs in reducing leakage and stabilizing switching characteristics, providing guidance for the development of transparent, low-power, and high-reliability BST-based RRAM devices. This study aims to investigate the role of Ba_0.6Sr_0.4TiO₃ (BST) ferroelectric oxide as a functional switching layer in resistive random-access memory (RRAM) and to evaluate how interface engineering using an electron transport layer (ETL) can improve resistive switching stability, leakage suppression, and device reliability.

In₂O₃ nanoparticles were obtained by annealing precursors that had been hydrothermally/solvothermally synthesized at 200 °C using In(NO₃)₃·4.5H₂O as the starting material. Three solvents were used for the synthesis, namely water, alcohol and ethylene glycol. Urea or glycine additives were introduced into the reaction mixtures as stabilizing and structure-forming agents. The nanopowders obtained were characterized using X-ray diffraction, scanning and transmission electron microscopy, low-temperature nitrogen adsorption and X-ray photoelectron spectroscopy. The gas-sensing characteristics of the indium oxide-based sensors were investigated for the detection of hydrogen in air. It has been established that the nature of the solvent determines the phase composition and structure of indium oxide, while organic additives reduce the particle size and increase the specific surface area. It should be noted that the addition of glycine to an alcohol solution of indium nitrate during synthesis produces a phase transformation. The results show that the sensor based on In₂O₃ synthesized using this mixture has the best hydrogen sensing properties of all the materials considered in this study.

Shape Memory Alloys (SMAs) have unique thermomechanical properties, including superelasticity and the shape memory effect, which has led them to be used in a wide range of applications, from biomedical devices to aerospace and civil engineering structures. These behaviors have been addressed by phenomenological models, which represent them by simply establishing stress-strain and transformation characteristics without accounting for the microstructure. In this review article, the main phenomenological modeling examples are categorized and compared, including the main principles of operation, predictions, and limitations under operating thermomechanical loading conditions. In addition, the growing use of SMAs, especially in actuation, damping, vibration control, and energy harvesting, is explored, and the incorporation of modeling frameworks into optimization activities is discussed. The final part of the review deals with open challenges and future research directions, consisting of the development of models that more accurately predict SMAs under cyclic and/or non-proportional loading, a more robust association with commercial computational tools, and exploring the use of SMAs in new interdisciplinary areas. By bridging modeling approaches to application-based concepts, a platform is provided for the advancement of both the scientific development and practical use of shape memory alloys.

Multi-beam and beam-scanning antennas enable extensive communication coverage while mitigating multipath fading and enhancing spectrum utilization efficiency. This paper presents a transmissive metasurface antenna design, which utilizes a microstrip square-ring patch antenna with four feed ports as the excitation source. A 7 × 7 square patch metasurface is positioned above the feed source, facilitating the generation of four independently steerable beams by switching activation among the four feed ports. Operating at 12.6 GHz, the antenna achieves a gain of 10.4 dB. The 3 dB beamwidth of the beams from all four ports exceeds 23°. The proposed design offers advantages of structural simplicity, low profile, and cost-effectiveness. By leveraging transmissive metasurfaces, this approach combines the benefits of low profile and low cost with flexible manipulation of electromagnetic wave radiation, thereby providing a novel methodology for designing multi-beam communication antennas.

Ultrasound transducers are fundamental components in medical imaging systems, impacting resolution, sensitivity, and penetration depth. A key challenge in designing high-performance ultrasound transducers is balancing bandwidth and sensitivity. This study focuses on optimizing the backing layer of a dual-frequency piezoelectric micromachined ultrasound transducer (PMUT) using polydimethylsiloxane (PDMS). COMSOL multi-physics version 6.2 finite element simulations and equivalent circuit modeling were employed to investigate the effects of PDMS backing layer thickness and geometry on frequency response characteristics, impedance matching, and acoustic sensitivity. The optimized PMUT structure demonstrated a significant enhancement in bandwidth, with the -6 dB bandwidth increasing to 92% at both 2.3 MHz and 6.8 MHz frequencies. The PDMS backing layer improved the matching of low- and high-frequency signals, enabling high sensitivity and reduced interface reflection losses. The incorporation of PDMS as the backing layer successfully expands the operational bandwidth of dual-frequency PMUTs while maintaining high sensitivity, offering promising potential for high-performance ultrasound imaging, particularly in medical applications requiring both deep penetration and high-resolution imaging.

Photoelectrochemical (PEC) biosensors have emerged as a significant research focus in the fields of bioanalysis and medical diagnostics in recent years due to their high sensitivity, low background noise, and ease of miniaturization. This review summarizes the fundamental principles of PEC biosensors, recent advances in photoactive materials, signal amplification strategies, and typical applications. Photoactive materials serve as the source of the sensor signal and can achieve signal enhancement through strategies such as heterostructure construction, localized surface plasmon resonance (LSPR) effects, and defect engineering. PEC sensors have been widely applied in areas such as cancer liquid biopsy and pathogen detection; however, challenges remain, including material biocompatibility, anti-interference capability in complex samples, and lack of standardized platforms. Future development trends include the design of green and low-toxicity photosensitive materials, integration with microfluidic and wearable devices, and artificial intelligence-assisted signal analysis, which will promote the translation of PEC biosensors toward clinical applications and real-time detection.

This work presents a comparative study on the ageing of supercapacitors and a method for monitoring their state of health (SoH) through mechanical deformation. This study aims to evaluate the accelerated ageing behaviours of these systems under specific cycling conditions and temperatures, allowing the establishment of a correlation between SoH and casing deformation in supercapacitors. Experimental ageing tests revealed supercapacitors displayed an initial "burning" phase followed by a linear ageing trend. Strain gauges were employed to measure the mechanical deformation of supercapacitor casings, providing real-time insights into their SoH. Capacitance fading in supercapacitors was modelled using Brunauer-Emmett-Teller (BET) theory, hypothesizing that gas adsorption during ageing significantly contributes to performance decline. Model predictions were validated against experimental data, demonstrating a clear correlation between capacitance fading, internal resistance, remaining energy, and casing deformation. This work highlights the potential of mechanical deformation monitoring as a practical and non-invasive approach for assessing the SoH of supercapacitors.

This research presents a novel dual-mode filter design that offers significant advantages in terms of frequency agility and miniaturization compared to conventional fixed multi-resonator filters. The design and implementation of a compact tunable bandpass filter are presented. The basic design structure is based on a slotted non-degenerate dual-mode microstrip square patch. The slots are etched symmetrically, which makes the slotted dual-mode square patch equivalent to a two-coupled-resonator filter. The asymmetrical feed lines enable the excitation of dual resonant modes. The patch length, slot size, and dielectric material properties primarily determine the filter's center frequency and bandwidth. Tunability is achieved by loading the slotted square patch with reversed bias varactor diodes located at the square patch corners, allowing electronic control of the filter center frequency. The design utilizes RT/Duroid 6010.2 laminates with a dielectric constant of 10.2 and a thickness of 0.635 mm. A bias tee at one of the filter ports is used to provide reverse bias to varactor diodes. Simulations and experimental results demonstrate tunable characteristics. Among the attractive features of the proposed design, good levels of insertion loss and impedance matching are noticed in the entire tunable band. The advantages of the proposed design make it well-suited for modern wireless technology applications in communication, radar, and satellite systems.