Micromachines

15 pages, 3594 KB

Open AccessArticle

High-Quality and High-Efficiency Fabrication of Microlens Array by Rotary Profile Cutting Method

by Liheng Gao, Xiuwen Sun, Qian Yu, Yinhui Wang, Md Nasir Uddin, Ruijue Duan, Gang Wang, Zhikang Zhou, Qiuchen Xie, Tao Sun and Tianfeng Zhou

Micromachines 2025, 16(12), 1374; https://doi.org/10.3390/mi16121374 (registering DOI) - 1 Dec 2025

Abstract

To enhance the fabrication consistency and surface quality of microlens array (MLA) molds, this study presents a high-quality and high-efficiency rotary profile-cutting (RPC) method conducted on a four-axis ultraprecision machining platform. A geometric model is established to define the relationship between tool parameters [...] Read more.

To enhance the fabrication consistency and surface quality of microlens array (MLA) molds, this study presents a high-quality and high-efficiency rotary profile-cutting (RPC) method conducted on a four-axis ultraprecision machining platform. A geometric model is established to define the relationship between tool parameters and microlens structural features, and the toolpath is optimized by refining control points to enhance machining accuracy. In addition, a novel tool-setting error characterization approach is developed, enabling submicron-level positioning of the diamond tool, with errors in the X and Y directions controlled within 1 μm. Experimental validation demonstrates the successful fabrication of a 6 × 6 square-array MLA mold with a curvature radius of 507 μm using the proposed RPC method. Subsequent replication of MLA through precision glass molding (PGM) yielded structures with a peak-to-valley (PV) value below 354 nm and surface roughness (Ra) below 11 nm. Optical performance tests confirm the high consistency and accuracy of the fabricated MLA, highlighting the potential of the proposed RPC technique for advanced optical component manufacturing. Full article

(This article belongs to the Special Issue Ultra-Precision Micro Cutting and Micro Polishing)

18 pages, 3295 KB

Open AccessArticle

Research on an Improved YOLOv8 Detection Method for Surface Defects of Optical Components

by Bei Ma, Jialong Zhao, Shun Zhou, Hongjun Wang, Junqi Xu, Bingcai Liu, Jingyao Hou and Weiguo Liu

Micromachines 2025, 16(12), 1373; https://doi.org/10.3390/mi16121373 (registering DOI) - 1 Dec 2025

Abstract

Optical components are extensively used in aerospace, microelectronic equipment, precision optical measurement, laser optics and other fields. Surface defects on optical components can significantly impact system performance, necessitating specialized detection methods. However, technical challenges persist in achieving high-resolution, high-precision and efficient optical surface [...] Read more.

Optical components are extensively used in aerospace, microelectronic equipment, precision optical measurement, laser optics and other fields. Surface defects on optical components can significantly impact system performance, necessitating specialized detection methods. However, technical challenges persist in achieving high-resolution, high-precision and efficient optical surface defect detection. To address this, we propose an improved YOLOv8-based object recognition algorithm. By incorporating the BRA attention mechanism into YOLOv8’s backbone network, multi-scale feature maps are processed to enhance adaptability to complex scenarios. Simultaneously, replacing the feature fusion module with the Context-GuideFPN module enables contextual guidance and adaptive adjustments during multi-scale feature integration without excessive computational overhead. Experimental results on our high-quality microscopic dark-field image dataset demonstrate that the enhanced BACG-YOLOv8 achieves excellent performance in optical component defect detection. The optimized network accurately extracts defect details, particularly demonstrating refined edge feature extraction while effectively suppressing noise interference. This significantly reduces detection errors and improves defect extraction accuracy. Full article

(This article belongs to the Section A：Physics)

10 pages, 1467 KB

Open AccessArticle

High-Efficiency Polariton Organic Photodetectors via Trap-Assisted Photomultiplication

by Jui-Fen Chang, Sung-Jung Lin, Yang-Ching Huang and Sheng-Ping Lin

Micromachines 2025, 16(12), 1372; https://doi.org/10.3390/mi16121372 - 1 Dec 2025

Abstract

We report a high-performance photomultiplication-type organic photodetector (OPD) based on a poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene]:[6,6]-phenyl-C₆₁-butyric acid methyl ester (MDMO-PPV:PC₆₁BM) active layer operating in the ultrastrong coupling regime. Systematic optimization of the PC₆₁BM ratio in reference non-cavity devices confirms that trap-assisted [...] Read more.

We report a high-performance photomultiplication-type organic photodetector (OPD) based on a poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene]:[6,6]-phenyl-C₆₁-butyric acid methyl ester (MDMO-PPV:PC₆₁BM) active layer operating in the ultrastrong coupling regime. Systematic optimization of the PC₆₁BM ratio in reference non-cavity devices confirms that trap-assisted hole injection from the Ag contact enables external quantum efficiencies (EQEs) exceeding 2000% and fast transient responses under 521 nm illumination, close to the absorption peak of MDMO-PPV. Incorporation of the optimized PC₆₁BM ratio into a λ/2 microcavity produces well-resolved lower (LP) and upper (UP) polariton branches with a pronounced Rabi splitting of approximately 0.9 eV, confirming the establishment of ultrastrong light–matter coupling. The resulting cavity OPD exhibits a distinct wavelength-dependent response compared with its non-cavity counterpart, achieving maximum EQEs of 838% at 450 nm (near the UP mode) and 445% at 628 nm (corresponding to the LP mode). These spectral responses are attributed to cavity-induced field modulation, which enhances exciton generation beyond the primary absorption band of MDMO-PPV. Overall, this work demonstrates that combining photomultiplication mechanisms with cavity-field engineering provides an effective strategy for realizing narrowband, high-gain polaritonic photodetectors that surpass the spectral response limitations of conventional organic semiconductors. Full article

(This article belongs to the Special Issue Nanostructured Optoelectronic and Nanophotonic Devices)

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40 pages, 2586 KB

Open AccessReview

Advances in NIR-II Fluorescent Nanoprobes: Design Principles, Optical Engineering, and Emerging Translational Directions

by Nargish Parvin, Mohammad Aslam, Md Najib Alam and Tapas K. Mandal

Micromachines 2025, 16(12), 1371; https://doi.org/10.3390/mi16121371 - 1 Dec 2025

Abstract

Fluorescent nanoprobes operating in the NIR-II window have gained considerable attention for biomedical imaging because of their deep-tissue penetration, reduced scattering, and high spatial resolution. Their tunable optical behavior, flexible surface chemistry, and capacity for multifunctional design enable sensitive detection and targeted visualization [...] Read more.

Fluorescent nanoprobes operating in the NIR-II window have gained considerable attention for biomedical imaging because of their deep-tissue penetration, reduced scattering, and high spatial resolution. Their tunable optical behavior, flexible surface chemistry, and capacity for multifunctional design enable sensitive detection and targeted visualization of biological structures in vivo. This review highlights recent advances in the design and optical engineering of four widely studied NIR-II nanoprobe families: quantum dots, carbon dots, upconversion nanoparticles, and dye-doped silica nanoparticles. These materials were selected because they offer well-defined architectures, controllable emission properties, and substantial mechanistic insight supporting discussions of imaging performance and translational potential. Particular focus is placed on emerging strategies for activatable, targeted, and ratiometric probe construction. Recent efforts addressing biosafety, large-scale synthesis, optical stability, and early preclinical validation are also summarized to clarify the current progress and remaining challenges that influence clinical readiness. By outlining these developments, this review provides an updated and focused perspective on how engineered NIR-II nanoprobes are advancing toward practical use in biomedical imaging and precision diagnostics. Full article

(This article belongs to the Section B：Biology and Biomedicine)

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30 pages, 11298 KB

Open AccessArticle

Quality Control Technology for Abrasive Flow Precision Machining of a High-Performance Impeller

by Junye Li, Songyuan Li, Pingping Wei, Changqing Wang, Yanming Li, Ke Liu, Chunlin Liu, Yu Chen, Guiling Wu, Xiao Li, Baicheng Liu, Jiyong Qu, Haihong Wu, Jun Zhang and Ziqiang Zhang

Micromachines 2025, 16(12), 1370; https://doi.org/10.3390/mi16121370 - 30 Nov 2025

Abstract

The surface quality of high-performance impellers, which feature complex, free-form surfaces and narrow flow channels, is critically important for their performance and efficiency. However, achieving uniform precision polishing on these intricate geometries remains a significant manufacturing challenge, as traditional methods are often inefficient, [...] Read more.

The surface quality of high-performance impellers, which feature complex, free-form surfaces and narrow flow channels, is critically important for their performance and efficiency. However, achieving uniform precision polishing on these intricate geometries remains a significant manufacturing challenge, as traditional methods are often inefficient, inaccessible, or cause surface damage. To address this, this study investigates the application of solid–liquid two-phase abrasive flow machining (AFM) as a high-precision finishing solution. Through numerical simulation, we analyzed the polishing effects under two flow channel structures and various machining parameters. The results demonstrate that a gradual flow channel structure significantly enhances processing uniformity and intensity compared to a direct flow channel. Furthermore, increasing the inlet pressure and abrasive viscosity was found to substantially improve both the strength and uniformity of the machining effect across the impeller surface. Experimental validation via an orthogonal test design confirmed that inlet pressure is the most influential factor on the polishing effect, followed by abrasive grain size and the number of processes. The optimized process parameters (6 MPa inlet pressure, 10 process cycles, and 40 µm abrasive grain size) successfully reduced the average surface roughness (Ra) of the high-performance impeller from 0.766 µm to 0.047 µm, representing an improvement of nearly 94%. This study provides a scientifically grounded set of optimal parameters for achieving uniform, high-quality surface finishing of complex impellers using AFM technology. Full article

(This article belongs to the Section E：Engineering and Technology)

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11 pages, 3556 KB

Open AccessArticle

The Impact of Load-Dump Stress on p-GaN HEMTs Under Floating Gate Condition

by Zhipeng Shen, Yijun Shi, Lijuan Wu, Liang He, Xinghuan Chen, Yuan Chen, Dongsheng Zhao, Jiahong He, Gengbin Zhu, Huangtao Zeng and Guoguang Lu

Micromachines 2025, 16(12), 1369; https://doi.org/10.3390/mi16121369 - 30 Nov 2025

Abstract

This work investigates the impact of load-dump stress on p-GaN HEMTs under floating gate condition. The experiments show that preconditioning the device with a small load-dump stress (150 V, @t_d = 100 ms and t_r = 8 ms) enhances its [...] Read more.

This work investigates the impact of load-dump stress on p-GaN HEMTs under floating gate condition. The experiments show that preconditioning the device with a small load-dump stress (150 V, @t_d = 100 ms and t_r = 8 ms) enhances its robustness against a larger stress (190 V, @t_d = 100 ms and t_r = 8 ms). If a large load-dump stress (≥160 V, @t_d = 100 ms and t_r = 8 ms) is applied directly to the device’s drain, the device will burn out. This occurs because the rapidly changing drain voltage during a load-dump event can generate a capacitive coupling current, leading to transient positive charge accumulation in the gate region. Consequently, the channel under the gate is turned on, allowing a large current to flow through it. The coexistence of high current and high voltage leads to substantial Joule heating within the device, resulting in eventual burnout. When a small load-dump stress is initially applied, the resulting charging of electron traps in the gate region increases the threshold voltage. As a result, the device can withstand a larger load-dump stress before the channel turns on, which explains the device’s enhanced robustness. This work clarifies the failure threshold of p-GaN HEMTs under the load-dump stress, providing key support for improving the devices’ reliability in the practical applications. It can provide a basis for adding necessary protective measures in device circuit design, and clarify the triggering voltage threshold of protective measures to ensure that they can effectively avoid device damage due to the load-dump stress. Full article

(This article belongs to the Special Issue Power Semiconductor Devices and Applications, 3rd Edition)

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25 pages, 1748 KB

Open AccessPerspective

Advancing In Vitro Microfluidic Models for Pressure-Induced Retinal Ganglion Cell Degeneration: Current Insights and Future Directions from a Biomechanical Perspective

by Tianyi Gao, Junhao Hao, Heather Mak, Zhiting Peng, Jing Wu, Qinyu Li and Yau Kei Chan

Micromachines 2025, 16(12), 1368; https://doi.org/10.3390/mi16121368 - 30 Nov 2025

Abstract

Glaucoma is the leading cause of irreversible blindness, primarily characterized by retinal ganglion cell (RGC) loss and optic nerve damage due to abnormal alterations in intraocular pressure (IOP). While in vivo models provide valuable insights into its pathophysiology, they face limitations in controlling [...] Read more.

Glaucoma is the leading cause of irreversible blindness, primarily characterized by retinal ganglion cell (RGC) loss and optic nerve damage due to abnormal alterations in intraocular pressure (IOP). While in vivo models provide valuable insights into its pathophysiology, they face limitations in controlling biomechanical parameters and long-term IOP monitoring. In vitro models offer greater experimental control but often lack the complexity of the ocular microenvironment, limiting their physiological relevance. To better understand RGC degeneration from a biomechanical perspective, advancements are needed to improve these models, including precise pressure manipulation and more realistic cell culture conditions. This review summarizes current in vitro approaches for studying pressure-induced RGC degeneration and explores the potential of microfluidic technologies to enhance model fidelity. Incorporating microfluidic technologies holds promise for creating more physiologically relevant models, potentially advancing our understanding of IOP-related RGC degeneration from biomechanical perspectives. Full article

(This article belongs to the Special Issue Microfluidic Chips for Biomedical Applications)

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9 pages, 2766 KB

Open AccessArticle

Simple Process for Flexible Light-Extracting QD Film and White OLED

by Eun Jeong Bae, Tae Jeong Hwang, Geun Su Choi, Yong-Min Lee, Byeong-Kwon Ju, Young Wook Park and Dong-Hyun Baek

Micromachines 2025, 16(12), 1367; https://doi.org/10.3390/mi16121367 - 30 Nov 2025

Abstract

Quantum dots (QDs) have tremendous potential for next-generation displays due to their high color purity, photoluminescence efficiency, and power efficiency. In this work, we present a simple and cost-effective method for fabricating flexible single- and multiple-layer films, and they can be detached and [...] Read more.

Quantum dots (QDs) have tremendous potential for next-generation displays due to their high color purity, photoluminescence efficiency, and power efficiency. In this work, we present a simple and cost-effective method for fabricating flexible single- and multiple-layer films, and they can be detached and attached to the outside of OLEDs as a light-scattering and color-conversion layer. Light extraction efficiency is enhanced by forming low-density structures by using the reactive ion etching (RIE) process. As a result, the QD/PDMS composite film allowed for color conversion and achieved an excellent light extraction efficiency of up to 9.2%. Furthermore, the QD/PDMS composite film and greenish-blue OLED produced white light (CIEx,y = 0.28, 0.41), demonstrating the potential for application in broad areas, from flexible displays to lighting. The method provides a simple and cost-effective alternative to conventional processes. Full article

(This article belongs to the Special Issue Advanced Thin-Films: Design, Fabrication and Applications, Third Edition)

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14 pages, 6451 KB

Open AccessArticle

Influence of High-Power Laser Cleaning on Oxide Layer Formation on 304L Stainless Steel

by Hyun Jong Yoo, HyeonSik Kang, Youngki Kim and Changkyoo Park

Micromachines 2025, 16(12), 1366; https://doi.org/10.3390/mi16121366 - 30 Nov 2025

Abstract

In this study, a kW-level high-power Nd:YAG nanosecond laser was adopted to eliminate a corrosion layer on a 304L stainless steel (SS304L) surface. Four different laser cleaning (LC) processes with various hatch distances and loop counts were adopted. The energy-dispersive X-ray spectroscopy (EDX) [...] Read more.

In this study, a kW-level high-power Nd:YAG nanosecond laser was adopted to eliminate a corrosion layer on a 304L stainless steel (SS304L) surface. Four different laser cleaning (LC) processes with various hatch distances and loop counts were adopted. The energy-dispersive X-ray spectroscopy (EDX) analysis revealed that the corrosion layer was successfully eliminated via the LC process. However, the electron probe X-ray microanalysis (EPMA) analysis confirmed that a Cr-based oxide layer with a thickness of a few micrometers had developed on the surface of SS304L by the LC process. Moreover, Cr-depleted regions were generated in the subsurface owing to the Cr consumption for oxide layer development. The surface temperature during the LC process strongly affected the thickness of oxide layers. The oxide layer and Cr-depletion formation can affect the subsequent manufacturing processes, including welding and molding. Moreover, those can influence the materials’ properties themselves, where the laser-cleaned workpieces may be used. Therefore, it is critical to characterize the relation between LC process parameters and microstructural alteration. Full article

(This article belongs to the Special Issue Ultrafast Laser Micro- and Nanoprocessing, 3rd Edition)

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15 pages, 8791 KB

Open AccessArticle

Design, Modeling, and Testing—A Compact Variable-Stiffness Actuator for Knee Joint Dimensions

by Guoning Si, Zilong Guo and Zhuo Zhang

Micromachines 2025, 16(12), 1365; https://doi.org/10.3390/mi16121365 - 29 Nov 2025

Abstract

Stroke rehabilitation exoskeletons require joint mechanisms capable of replicating physiological stiffness modulation to adapt to varying gait phases. This paper presents a novel compact variable-stiffness mechanism (VSM) for knee exoskeletons, based on a simplified three-bar linkage topology. The proposed design achieves a pre-configurable [...] Read more.

Stroke rehabilitation exoskeletons require joint mechanisms capable of replicating physiological stiffness modulation to adapt to varying gait phases. This paper presents a novel compact variable-stiffness mechanism (VSM) for knee exoskeletons, based on a simplified three-bar linkage topology. The proposed design achieves a pre-configurable quasi-stiffness range of 0.15–2.0 NM/deg. Static characterization under a 2 kg load demonstrated up to 23.0 N of collision force attenuation in softening regimes (λ < 2.3) through passive viscoelastic dissipation, whereas hardening behavior (λ ≥ 2.3) preserved precise torque-angle characteristics scalable to physiological loading. A parametric analysis showed an 89% correlation between the theoretical and scaled experimental stiffness profiles for values from 0.5 to 2.5. The proposed architecture enables decoupled optimization of impact safety and positional precision, offering a clinically adaptable solution for hemiparetic gait assistance. Full article

(This article belongs to the Section E：Engineering and Technology)

32 pages, 12481 KB

Open AccessArticle

Design and Validation of a Brain-Controlled Hip Exoskeleton for Assisted Gait Rehabilitation Training

by Chengjun Wang, Biao Cheng, Qiang Tang, Renyuan Wu and Huanyu Li

Micromachines 2025, 16(12), 1364; https://doi.org/10.3390/mi16121364 - 29 Nov 2025

Abstract

This study presents an integrated micro-system solution to address the challenges of gait instability in patients with impaired hip motor function. We developed a novel wearable hip exoskeleton, where a flexible support unit and a parallel drive mechanism achieve self-alignment with the biological [...] Read more.

This study presents an integrated micro-system solution to address the challenges of gait instability in patients with impaired hip motor function. We developed a novel wearable hip exoskeleton, where a flexible support unit and a parallel drive mechanism achieve self-alignment with the biological hip joint to minimize parasitic forces. The system is driven by an active brain–computer interface (BCI) that synergizes an augmented reality visual stimulation (AR-VS) paradigm for enhanced motor intent recognition with a high-performance decoding algorithm, all implemented on a real-time embedded processor. This integration of micro-sensors, control algorithms, and actuation enables the establishment of a gait phase-dependent hybrid controller that optimizes assistance. Online experiments demonstrated that the system assisted subjects in completing 10 gait cycles with an average task time of 37.94 s, a correlated instantaneous rate of 0.0428, and an effective output ratio of 82.17%. Compared to traditional models, the system achieved an 18.64% reduction in task time, a 28.31% decrease in instantaneous rate, and a 7.36% improvement in output ratio. This work demonstrates a significant advancement in intelligent micro-system platforms for human-centric rehabilitation robotics. Full article

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15 pages, 2247 KB

Open AccessArticle

A Pathway to High-Quality Heteroepitaxial Ga₂O₃ Films via Metalorganic Chemical Vapor Deposition

by Yifan Li, Yachao Zhang, Kelin Wang, Guoliang Peng, Shengrui Xu, Qian Feng, Jinbang Ma, Yixin Yao, Yue Hao and Jincheng Zhang

Micromachines 2025, 16(12), 1363; https://doi.org/10.3390/mi16121363 - 29 Nov 2025

Abstract

This work systematically investigates the heteroepitaxial growth of β-Ga₂O₃ thin films under varied substrate and temperature conditions via metalorganic chemical vapor deposition (MOCVD). Comprehensive characterization reveals that both the substrate type and growth temperature significantly influence the crystalline quality, surface [...] Read more.

This work systematically investigates the heteroepitaxial growth of β-Ga₂O₃ thin films under varied substrate and temperature conditions via metalorganic chemical vapor deposition (MOCVD). Comprehensive characterization reveals that both the substrate type and growth temperature significantly influence the crystalline quality, surface morphology, chemical composition, and defect structure. Films grown at higher temperatures generally exhibit superior crystallinity and closer-to-stoichiometry composition, and thus suggest a reduction in oxygen deficiency. Certain substrates are shown to facilitate high-quality epitaxial growth with smooth surfaces and excellent crystallographic alignment. These findings offer key insights into optimizing growth parameters for high-performance β-Ga₂O₃-based devices. Full article

(This article belongs to the Topic Wide Bandgap Semiconductor Electronics and Devices)

10 pages, 2350 KB

Open AccessArticle

Design of Dual Continuous-Mode Class-J Power Amplifiers with Harmonic Matching Networks for X and Ku Bands

by Yang Yuan, Xuesong Zhao, Jingxin Fan and Zhongjun Yu

Micromachines 2025, 16(12), 1362; https://doi.org/10.3390/mi16121362 - 29 Nov 2025

Abstract

In this article, two wideband high-efficiency Class-J power amplifiers operating in X and Ku bands, respectively, are designed based on continuous mode. The optimal impedance regions of the transistors are determined using harmonic load-pull techniques. An on-chip output matching network with second harmonic [...] Read more.

In this article, two wideband high-efficiency Class-J power amplifiers operating in X and Ku bands, respectively, are designed based on continuous mode. The optimal impedance regions of the transistors are determined using harmonic load-pull techniques. An on-chip output matching network with second harmonic control functionality is designed to achieve Class-J operation. To verify the feasibility of designed circuits, both power amplifiers are designed and fabricated using a 0.25 mm GaAs pseudomorphic high electron mobility transistor (pHEMT) process. The power amplifiers are both biased at 6 V/−1 V. The measured results show the X-band and Ku-band power amplifiers achieve peak saturated output powers of 31.2 dBm and 30.8 dBm, respectively. The power-added efficiencies (PAEs) of the two amplifiers within their operating bands reach up to 48% and 45.3%, respectively. Compact size and high efficiency make them suitable for integration into phased array transmit/receiver (T/R) modules. Full article

(This article belongs to the Special Issue Broadband Terahertz Devices and Communication Technologies, 2nd Edition)

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17 pages, 5239 KB

Open AccessArticle

Low-Loss Multimode Waveguide Bends with Direct Laser Writing in Polymer

by Tigran Baghdasaryan, Neshteh Kourian, Mushegh Rafayelyan and Tatevik Sarukhanyan

Micromachines 2025, 16(12), 1361; https://doi.org/10.3390/mi16121361 - 29 Nov 2025

Abstract

Waveguide bends are critical components for compact routing in integrated photonic circuits, yet their design in air-clad polymer waveguides fabricated by two-photon polymerization direct laser writing (2PP-DLW) is challenging due to multimode behavior. We address this by systematically modeling Bézier-shaped 90° bends and [...] Read more.

Waveguide bends are critical components for compact routing in integrated photonic circuits, yet their design in air-clad polymer waveguides fabricated by two-photon polymerization direct laser writing (2PP-DLW) is challenging due to multimode behavior. We address this by systematically modeling Bézier-shaped 90° bends and S-bends using a variational FDTD solver, exploring bend span, curvature, and waveguide dimensions. Our results show that smaller waveguides (widths 2–4 µm) and lower Bézier parameters (B = 0–0.2) consistently yield superior performance, enabling sharper bends with minimal loss. For 90° bends, spans as small as 20–30 µm achieve near-unity transmission, while for S-bends, aspect ratios below 1 are feasible, allowing highly compact layouts. Although all configurations transmit energy to the fundamental mode, wider waveguides exhibit stronger higher-order mode excitation and greater sensitivity to fabrication imperfections. Smaller waveguides reduce these effects but approach the resolution limits of 2PP-DLW. Thus, a 2 µm wide waveguide represents an optimal compromise between fabrication feasibility and optical performance. Experimental demonstrations confirm the practicality of these design rules, illustrating trends predicted by simulations. These findings establish clear guidelines for designing low-loss, space-efficient 3D photonic circuits and highlight the critical role of simulation-driven optimization in fully exploiting 2PP-DLW technology, while providing deeper insight for future device architectures. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication, Second Edition)

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11 pages, 1618 KB

Open AccessArticle

Demolding Simulation of Propagation Phase Metasurfaces via Roll-to-Plate Nanoimprint

by Bowen Hu, Hao Chen, Dizhi Sun and Liangui Deng

Micromachines 2025, 16(12), 1360; https://doi.org/10.3390/mi16121360 - 29 Nov 2025

Abstract

Propagation phase metasurfaces have excellent electromagnetic regulation and polarization-insensitive properties, while roll-to-plate nanoimprint lithography (R2P-NIL) is ideal for their large-scale low-cost fabrication. Existing demolding simulations for R2P-NIL are limited to 2D analysis, ignore elastomeric roller impacts, and cannot handle the discrete pillar/hole structures [...] Read more.

Propagation phase metasurfaces have excellent electromagnetic regulation and polarization-insensitive properties, while roll-to-plate nanoimprint lithography (R2P-NIL) is ideal for their large-scale low-cost fabrication. Existing demolding simulations for R2P-NIL are limited to 2D analysis, ignore elastomeric roller impacts, and cannot handle the discrete pillar/hole structures of such metasurfaces. This study establishes a 3D multiscale simulation model using a finite element method combining a macroscopic elastomeric roller deformation model and a microscopic demolding stress model with motion equation-based parameter transfer. Simulation results show macroscopically that zero elastomeric layer thickness minimizes stress, while stress rises and then stabilizes with increasing thickness; a moderately larger roller radius disperses stress; excessive pressure amplifies stress; a microscopically higher resist elastic modulus lowers stress; cylindrical structures have less stress than cuboids; and the limit aspect ratio peaks at a 100 nm line width. This work provides theoretical support for R2P-NIL parameter optimization and promotes the stable large-scale production of propagation phase metasurfaces. Full article

(This article belongs to the Special Issue Fabrication of Functional Surface Microstructures)

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4 pages, 167 KB

Open AccessEditorial

Droplet Microfluidics: From Generation to Manipulation

by Nan Xiang, Lin Jiang and Zhonghua Ni

Micromachines 2025, 16(12), 1359; https://doi.org/10.3390/mi16121359 - 29 Nov 2025

Abstract

Microfluidics is a powerful technique that manipulates fluid flow within microscale channels, enabling highly precise and reproducible fluid control in extremely small confined spaces [...] Full article

12 pages, 5301 KB

Open AccessArticle

Dynamics of h-Shaped Pulse to GHz Harmonic State in a Mode-Locked Fiber Laser

by Lin Wang, Guoqing Hu, Yan Wang, Guangwei Chen, Liang Xuan, Zhehai Zhou and Jun Yu

Micromachines 2025, 16(12), 1358; https://doi.org/10.3390/mi16121358 - 29 Nov 2025

Abstract

We experimentally and through simulations demonstrate a passively mode-locked fiber laser based on nonlinear polarization rotation, which generates the evolution from h-shaped pulses to GHz harmonic trains. When the polarization angle is continuously changed, the h-shaped pulse sequentially evolves into multiple pulses, bunched [...] Read more.

We experimentally and through simulations demonstrate a passively mode-locked fiber laser based on nonlinear polarization rotation, which generates the evolution from h-shaped pulses to GHz harmonic trains. When the polarization angle is continuously changed, the h-shaped pulse sequentially evolves into multiple pulses, bunched solitons, and harmonic pulses. The maximum order of harmonic trains obtained in experiments is 120, corresponding to the repetition frequency of 1.03996 GHz. The coupled Ginzburg-Landau equation and two-time-scale approach to gain is provided to characterize the laser physics. The fast and slow evolution of gain contributes to the stabilization and length of one soliton pattern, respectively. The proposed fiber laser is cost effective and easy to implement, providing a potential way to study soliton dynamics in depth. Full article

(This article belongs to the Special Issue Integrated Photonics and Optoelectronics, 2nd Edition)

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20 pages, 3588 KB

Open AccessArticle

Design of a Portable Nondestructive Instrument for Apple Watercore Grade Classification Based on 1DQCNN and Vis/NIR Spectroscopy

by Haijian Wu, Yong Lin, Wenbin Zhang, Zikang Cao, Chunlin Zhao, Zhipeng Yin, Yue Lu, Liju Liu and Ding Hu

Micromachines 2025, 16(12), 1357; https://doi.org/10.3390/mi16121357 - 29 Nov 2025

Abstract

To address the challenge of nondestructively identifying watercore disease in apples during growth and maturation, a portable device was developed for real-time grading of apple watercore using visible/near-infrared (Vis/NIR) spectroscopy combined with a one-dimensional quadratic convolutional neural network (1DQCNN). The instrument enables rapid, [...] Read more.

To address the challenge of nondestructively identifying watercore disease in apples during growth and maturation, a portable device was developed for real-time grading of apple watercore using visible/near-infrared (Vis/NIR) spectroscopy combined with a one-dimensional quadratic convolutional neural network (1DQCNN). The instrument enables rapid, nondestructive, and accurate detection of apple watercore grades. The AI-OX2000-13 micro-spectrometer is used as the core data acquisition unit, and an ARM processing system is built with the STM32F103VET6 as the main control chip. A 4G wireless communication module enables efficient and stable data transmission between the processor and computer, meeting the real-time detection needs of apple watercore content in orchard environments. To improve the scientific and accurate classification of watercore grades, this paper combines the BiSeNet and RIFE algorithms to construct a 3D model of apple watercore, allowing quantification of the degree of watercore and classification into four levels. Based on this, quadratic convolution operations are incorporated into a one-dimensional convolutional neural network (1DCNN), leading to the development of the 1D quadratic convolutional neural network (1DQCNN) model for watercore grade classification. Experimental results indicate that the model achieves a classification accuracy of 98.05%, outperforming traditional methods and conventional CNN models. The designed portable instrument demonstrates excellent accuracy and practicality in real-world applications. Full article

(This article belongs to the Section B：Biology and Biomedicine)

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18 pages, 2718 KB

Open AccessReview

The Principle and Development of Optical Maskless Lithography Based Digital Micromirror Device (DMD)

by Xianjie Li, Guodong Cui and Guili Xu

Micromachines 2025, 16(12), 1356; https://doi.org/10.3390/mi16121356 - 29 Nov 2025

Abstract

A comprehensive review of the DMD-based optical lithography system has been conducted. The essence of the point-array with an oblique-scanning and stepping operation principle has been systematically analyzed, which will serve as the core driving force for its development and application. Similar to [...] Read more.

A comprehensive review of the DMD-based optical lithography system has been conducted. The essence of the point-array with an oblique-scanning and stepping operation principle has been systematically analyzed, which will serve as the core driving force for its development and application. Similar to conventional lithography, the system development has been presented from the aspects of critical dimension (CD) resolution, overlay accuracy, and throughput. With the unique characterizations of the digital virtue mask, achievements are summarized from integrated circuit (IC) manufacturing to various micro-scale fabrication processes. Full article

(This article belongs to the Special Issue Recent Advances in Lithography)

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19 pages, 2657 KB

Open AccessArticle

Fourier Approximation of magMEMS Oscillations: Neural Network Space Handling

by Piotr Skrzypacz, Arman Bolatov, Andrzej Dziedzic, Grant Ellis, Kaisar Tangirbergen, Bartosz Pruchnik and Piotr Putek

Micromachines 2025, 16(12), 1355; https://doi.org/10.3390/mi16121355 - 28 Nov 2025

Abstract

The initial value problem for a model of magnetic Micro-Electro-Mechanical System (magMEMS) with current-carrying conductors is considered. The model equation is a conservative MEMS oscillator due to the presence of the singular term corresponding to the magnetic force between two current-conducting wires. If [...] Read more.

The initial value problem for a model of magnetic Micro-Electro-Mechanical System (magMEMS) with current-carrying conductors is considered. The model equation is a conservative MEMS oscillator due to the presence of the singular term corresponding to the magnetic force between two current-conducting wires. If the excitation parameter is below a certain threshold, the actuator oscillates. Fourier approximation of periodic solutions is enhanced by neural network space handling for both the limiting case where the geometric parameter approaches zero and the general case with arbitrary geometric parameter values. The method is validated through numerical comparisons with high-precision solutions, and its limitations are identified during the verification of experimental results. The findings can be useful for the design of magMEMS models. Full article

(This article belongs to the Section E：Engineering and Technology)

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15 pages, 3213 KB

Open AccessArticle

Process Optimization for Metal-Contact Etching in 3D Integration Devices

by Sung Gyu Pyo

Micromachines 2025, 16(12), 1354; https://doi.org/10.3390/mi16121354 - 28 Nov 2025

Abstract

This study investigates a metal-contact etching process that differs from conventional device contact etching by focusing on the film-stack configuration and the associated super-contact etching characteristics. Because metal-contact etching is closely linked to both physical profiles and electrical performance, evaluating a single parameter [...] Read more.

This study investigates a metal-contact etching process that differs from conventional device contact etching by focusing on the film-stack configuration and the associated super-contact etching characteristics. Because metal-contact etching is closely linked to both physical profiles and electrical performance, evaluating a single parameter provides limited insight; thus, the physical profile characteristics of metal-contact etching and 3D-integrated super-contacts were comprehensively examined. In the first-step etch, the target depth in the wafer left region was approximately 2365 Å, and the bottom surface exhibited a desirable rounded profile. Following the removal of liner TEOS and nitride, the stopping margin was evaluated under three conditions: (1) metal-contact etching with a ~22 s target reduction, (2) a CMOS image-sensor baseline incorporating an interlayer-dielectric-reduction scheme, and (3) a high-selectivity condition achieved by increasing the C₅F₈/O₂ ratio with a reduced etch target. Under all three conditions, the bit-line contact (BLC) nitride experienced punch-through. To address this limitation, a three-step etch sequence was implemented, in which the first two steps achieved the required etch depth and the final step utilized a high-selectivity over-etch to secure a sufficient stopping margin. This approach demonstrated robust process windows, favorable CD control, and reliable nitride stopping performance, thereby establishing a practical methodology for stable super-contact etching in advanced 3D-integrated logic applications. Full article

(This article belongs to the Special Issue Advanced Packaging for Microsystem Applications, 4th Edition)

20 pages, 2040 KB

Open AccessArticle

Effect of Random Base Vibrations on the Performance of Piezoelectric Wind Energy Harvesters

by Alberto Pasetto, Michele Tonan, Matteo Bottin and Alberto Doria

Micromachines 2025, 16(12), 1353; https://doi.org/10.3390/mi16121353 - 28 Nov 2025

Abstract

Piezoelectric wind energy harvesters can collect a small amount of energy from wind without the need for rotary equipment. In practice, such harvesters can be excited concurrently by wind-induced and base vibrations. In this study, combined wind and base excitation is investigated, with [...] Read more.

Piezoelectric wind energy harvesters can collect a small amount of energy from wind without the need for rotary equipment. In practice, such harvesters can be excited concurrently by wind-induced and base vibrations. In this study, combined wind and base excitation is investigated, with a focus on random base vibrations and the effect of the bandwidth of band-limited random excitation, thereby filling the research gap between results obtained with wide-band random excitation and those with harmonic excitation. Since flow-induced vibrations can produce several phenomena, in this research, galloping and vortex-induced vibration (VIV) harvesters are considered due to their structural similarity and the ease with which a galloping harvester can be converted into a VIV harvester (and vice versa). Both numerical and experimental results are presented. First, the mathematical models are given; then, experimental tests validate the models and provide an insight into the phenomena; finally, numerical simulations extend the dissertation by providing a more in-depth analysis of the behavior of such harvesters. The results show that above the critical wind velocity, galloping harvesters are not affected by the amplitude and bandwidth of random base excitation. In contrast, VIV harvesters in the lock-in condition are affected by random base excitation, especially if the vibration amplitude is large and if its spectrum is concentrated in a narrow band centered about the resonance. Full article

(This article belongs to the Special Issue Research Progress on Advanced Piezoelectric Energy Harvesters)

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18 pages, 23546 KB

Open AccessArticle

A High-Performance Ordered Routing Algorithm for Large-Scale WLCSP with Multi-Capacity

by Chuandong Chen, Dishi Lin, Qinghai Liu and Zhifeng Lin

Micromachines 2025, 16(12), 1352; https://doi.org/10.3390/mi16121352 - 28 Nov 2025

Abstract

Redistribution layer ordered routing is a critical problem in fan-out wafer-level chip-scale packaging (WLCSP) design. The traditional integer linear programming (ILP) method is inefficient in dealing with the ordered routing problem of multiple-capacity. Hence, we propose a high-performance ordered routing algorithm to solve [...] Read more.

Redistribution layer ordered routing is a critical problem in fan-out wafer-level chip-scale packaging (WLCSP) design. The traditional integer linear programming (ILP) method is inefficient in dealing with the ordered routing problem of multiple-capacity. Hence, we propose a high-performance ordered routing algorithm to solve the multiple-capacity ordered routing problem on the redistribution layer (RDL). First, we transform the ordered routing problem into the min-cost multi-commodity flow (MMCF) problem and use the linear programming (LP) method to solve it. Then, we use depth-first search (DFS) to process the LP method flow results and obtain the pre-assignment I/O candidate paths. Finally, the candidate path set obtains legal routing results by setting the crossing weight and a heuristic algorithm to receive the minimum crossing weight. When the pre-assignment I/O routing is uncompleted, we will set the capacity of tile nodes and edges to 0 and perform iterative routing for better results. Compared with the state-of-the-art work, experimental results show that our algorithm can solve twice the scale of the RDL ordered routing problems and reduce the routing time by 17% when dealing with multi-capacity RDL ordered routing problems. Full article

(This article belongs to the Section D1: Semiconductor Devices)

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12 pages, 1394 KB

Open AccessArticle

Power-Law Time Exponent n and Time-to-Failure in 4H-SiC MOSFETs: Beyond Fixed Reaction–Diffusion Theory

by Mamta Dhyani, Smriti Singh, Nir Tzhayek and Joseph B. Bernstein

Micromachines 2025, 16(12), 1351; https://doi.org/10.3390/mi16121351 - 28 Nov 2025

Abstract

This work investigates bias-temperature instability (BTI) in 1700 V 4H-SiC MOSFETs under realistic 1 MHz switching conditions with simultaneous gate and drain stress. Threshold-voltage measurements reveal that the degradation does not follow the classical Reaction–Diffusion behavior typically assumed for silicon devices. Instead, the [...] Read more.

This work investigates bias-temperature instability (BTI) in 1700 V 4H-SiC MOSFETs under realistic 1 MHz switching conditions with simultaneous gate and drain stress. Threshold-voltage measurements reveal that the degradation does not follow the classical Reaction–Diffusion behavior typically assumed for silicon devices. Instead, the power-law exponent n shows a clear increase at the largest negative gate bias (−10 V), indicating a field-driven trap-generation mechanism. Temperature-dependent stress tests further show a negative activation energy (−0.466 eV), consistent with degradation accelerating at lower temperatures due to suppressed detrapping. The results demonstrate that conventional silicon BTI models cannot be directly applied to SiC technologies and that fixed-n lifetime extrapolation leads to significant errors. A bias-dependent, field-driven framework for estimating time-to-failure is proposed, offering more accurate and practical reliability prediction for high-power SiC converter applications. Full article

(This article belongs to the Collection Women in Micromachines)

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18 pages, 8768 KB

Open AccessArticle

Simulation Analysis of the Chemical Mechanical Polishing Process for Monocrystal 4H-Silicon Carbide Based on Molecular Dynamics

by Yang Lei, Weigang Guo, Kaiping Feng and Zitong Sun

Micromachines 2025, 16(12), 1350; https://doi.org/10.3390/mi16121350 - 28 Nov 2025

Abstract

This paper delves into the mechanism of the chemical and mechanical action during chemical mechanical polishing (CMP) of monocrystal silicon carbide (SiC) through the molecular dynamics (MD) method. The oxidation simulation showed that the Si atoms mainly reacted in the form of Si-O [...] Read more.

This paper delves into the mechanism of the chemical and mechanical action during chemical mechanical polishing (CMP) of monocrystal silicon carbide (SiC) through the molecular dynamics (MD) method. The oxidation simulation showed that the Si atoms mainly reacted in the form of Si-O and Si-H, while the C atoms are in the form of C-O. The impact of the sliding depth and the polishing speed on the SiC workpiece was analyzed. Results show that more substrate atoms are removed as the polishing depth and speed increase. When the polishing depth reached 8 angstroms, 624 atoms were removed from the substrate. At the same time, the increased diamond polishing speed expands the polishing area. This reduces the indentation of the cut atoms on the surface of the workpiece and increases the removal efficiency of the SiC surface atoms, and when the polishing speed reached 125 m/s, the instantaneous temperature reached about 800 °C. In short, the polishing depth and speed have a significant impact on the polishing process, and the polishing depth has a more sophisticated influence on the atom removal rate. Full article

(This article belongs to the Special Issue Novel Processes for Cutting, Grinding and Polishing of Microstructured Surfaces)

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13 pages, 7834 KB

Open AccessArticle

Enhancement of Fluoride Retention in Human Enamel Using Low-Energy Blue Diode Laser (445 nm): An Ex Vivo Study

by Melanie Namour, Marwan El Mobadder, Ilaria Giovannacci, Alain Vanheusden and Samir Nammour

Micromachines 2025, 16(12), 1349; https://doi.org/10.3390/mi16121349 - 28 Nov 2025

Abstract

Aim: This ex vivo study aimed to evaluate the effect of low-energy 445 nm diode laser irradiation on permanent fluoride retention in human enamel. Materials and Methods: Eighty caries-free extracted permanent human teeth were used to prepare 480 enamel discs (2 × 2 [...] Read more.

Aim: This ex vivo study aimed to evaluate the effect of low-energy 445 nm diode laser irradiation on permanent fluoride retention in human enamel. Materials and Methods: Eighty caries-free extracted permanent human teeth were used to prepare 480 enamel discs (2 × 2 mm). Baseline fluoride content in untreated enamel specimens (control group E) was measured using particle-induced gamma-ray emission (PIGE). All specimens then received a topical application of acidulated phosphate fluoride for 5 min, followed by rinsing with double-distilled water for 1 min. Fluoride quantification was subsequently repeated. Specimens were randomly allocated into two groups: fluoridated only (EF; n = 240) and fluoridated plus laser-treated (EFL; n = 240). Each group was further subdivided based on storage conditions: either in air or in double-distilled water at 36 °C for 7 days. Laser irradiation was performed using a 445 nm diode laser in continuous-wave mode at 350 mW for 30 s, with a beam diameter of 10 mm, an energy density of 13.375 J/cm², and a power density of 0.445 W/cm². Results: At baseline, mean fluoride content across all specimens was 702.23 ± 201 ppm. Immediately after fluoridation, fluoride levels increased to 11,059 ± 386 ppm in the EF group and 10,842 ± 234 ppm in the EFL group, with no significant difference between groups. After 7 days of storage in air, fluoride retention decreased to 5714 ± 1162 ppm in EF and 5973 ± 861 ppm in EFL, again without significant difference. However, after 7 days of immersion in double-distilled water, the EF group exhibited complete loss of acquired fluoride, with values falling below baseline (337 ± 150 ppm). In contrast, the EFL group retained a substantial portion of the fluoride acquired during fluoridation (total 1533 ± 163 ppm), indicating that laser irradiation significantly prevented fluoride loss (p < 0.001). Conclusions: Low-energy 445 nm diode laser irradiation of fluoridated enamel significantly enhances fluoride retention under aqueous conditions simulating osmotic processes. Laser treatment preserved a substantial portion of fluoride acquired during fluoridation, whereas fluoridated but unlased enamel lost nearly all fluoride, with levels dropping below baseline. This approach may offer clinical benefits for improving enamel fluoride enrichment, thereby increasing resistance to acid challenge and reducing caries risk. Full article

(This article belongs to the Special Issue Laser Micro/Nano-Fabrication)

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10 pages, 2300 KB

Open AccessArticle

Universal Logic-in-Memory Gates Using Reconfigurable Silicon Transistors

by Sunhyuk Kim, Nahyeon Kim, Yaeyeon Ko and Doohyeok Lim

Micromachines 2025, 16(12), 1348; https://doi.org/10.3390/mi16121348 - 28 Nov 2025

Abstract

This study aims to implement universal logic gates using polarity control within a single silicon transistor structure. For this purpose, a reconfigurable transistor based on a p-i-n structure featuring two polarity gates (PGs) and one control gate was proposed, and its electrical characteristics [...] Read more.

This study aims to implement universal logic gates using polarity control within a single silicon transistor structure. For this purpose, a reconfigurable transistor based on a p-i-n structure featuring two polarity gates (PGs) and one control gate was proposed, and its electrical characteristics and logic-in-memory (LIM) circuit operations were analyzed via two-dimensional technology computer-aided design simulations. The proposed device could be perfectly reconfigured into p-channel or n-channel modes because virtual doping effects could be induced according to the polarity of the PG voltage. Moreover, based on the positive feedback and latch-up phenomena, a steep subthreshold swing of approximately 1 mV/dec and a high ON/OFF current ratio of the order of 10¹⁰ were achieved. Building on these characteristics, we successfully verified NAND LIM operation in the p-channel mode and NOR LIM operation in the n-channel mode by connecting two of the proposed devices in parallel. The reconfigurable silicon transistor proposed in this study could perform both NAND and NOR LIM operations while sharing the same device structure and can be expected to play a key role in implementing high-density, low-power LIM systems in the future. Full article

(This article belongs to the Section D1: Semiconductor Devices)

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17 pages, 3671 KB

Open AccessReview

A Review of Transverse Mode Adaptive Control Based on Photonic Lanterns

by Yao Lu, Zongfu Jiang, Zilun Chen, Zhuruixiang Sun and Tong Liu

Micromachines 2025, 16(12), 1347; https://doi.org/10.3390/mi16121347 - 28 Nov 2025

Abstract

With the widespread application of fiber laser technology in industries, communications, medical fields, and beyond, the demand for controlling the spatial modes of their output beams has been increasingly growing. Traditional mode control methods are constrained by factors such as device power thresholds, [...] Read more.

With the widespread application of fiber laser technology in industries, communications, medical fields, and beyond, the demand for controlling the spatial modes of their output beams has been increasingly growing. Traditional mode control methods are constrained by factors such as device power thresholds, system complexity, and cost, making it difficult to meet the requirements for high-power, high-purity, and rapidly switchable multimode regulation. This paper reviews adaptive mode control technology based on photonic lanterns (PLs). By integrating ideas from adaptive optics and photonics, this technology utilizes photonic lanterns to achieve efficient mode evolution from single-mode to multimode fibers. Combined with optimization algorithms, it enables real-time regulation of input phases, thereby producing stable, high-purity target modes or mode superposition fields at the multimode output end. The paper systematically introduces the structural classifications, propagation characteristics, and fabrication processes of photonic lanterns, as well as the mode evolution mechanisms in different types of photonic lanterns. It elaborates in detail on the structural design, algorithm implementation, and experimental validation of the adaptive control system based on photonic lanterns. Furthermore, it explores the application prospects of this technology in areas such as suppressing transverse mode instability, mode-division multiplexing communications, particle manipulation, and high-resolution spectral measurements. The results demonstrate that the all-fiber adaptive mode control system based on photonic lanterns offers advantages such as compact structure, low loss, fast response, and strong scalability. Full article

(This article belongs to the Special Issue Photonic and Optoelectronic Devices and Systems, Third Edition)

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10 pages, 2960 KB

Open AccessArticle

High-Precision Optical Angle Detection Method for Two-Dimensional MEMS Mirrors

by Longqi Ran, Yan Wang, Zhongrui Ma, Ting Li, Jiangbo He, Jiahao Wu and Wu Zhou

Micromachines 2025, 16(12), 1346; https://doi.org/10.3390/mi16121346 - 28 Nov 2025

Abstract

As a core component of MEMS LiDAR, the 2D MEMS mirror, with high-precision optical angle detection, is a key technology for radar scanning and imaging. Existing piezoresistive detection schemes of mirrors suffer from high fabrication complexity, high temperature sensitivity, and a limited accuracy [...] Read more.

As a core component of MEMS LiDAR, the 2D MEMS mirror, with high-precision optical angle detection, is a key technology for radar scanning and imaging. Existing piezoresistive detection schemes of mirrors suffer from high fabrication complexity, high temperature sensitivity, and a limited accuracy of only 0.08°, failing to meet the requirements for vehicular and airborne scanning applications. This study focuses on a two-dimensional electromagnetic MEMS mirror. Based on the reflection principles of geometric optics, angle detection schemes with photodiode (PD) arrays are analyzed. A novel four-quadrant optical measurement sensor featuring a 16-PD array is proposed. This design replaces conventional large-area PDs with a compact PD array, effectively mitigating nonlinearity and low accuracy issues caused by oversized PD trenches and edge dimensions. High-precision detection of the mirror’s deflection angle is achieved by measuring the current variations induced by the reflected spot position on the PDs in each quadrant. The experimental results demonstrate that the 16-PD array optical angle sensor achieves an accuracy between 0.03° and 0.036° over a detection range of ±8°. Full article

(This article belongs to the Special Issue Micro- and Nanosensors: Fabrication, Applications and Performance Enhancements, Third Edition)

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12 pages, 3473 KB

Open AccessArticle

Transmission Efficiency of a MEMS Laser Fuze for Safety and Arming

by Kuang Fang, Shanglong Xu, Wenzhi Qin, Jiangnan Ran, Chao Chen, Peng Yang and Yalong Dai

Micromachines 2025, 16(12), 1345; https://doi.org/10.3390/mi16121345 - 28 Nov 2025

Abstract

Owing to their superior performance in countering electromagnetic interference on the battlefield, laser fuzes have become a promising candidate for application in munition systems. However, as the short-pulse laser is activated by an electrical signal, the possibility of accidental emissions caused by logic [...] Read more.

Owing to their superior performance in countering electromagnetic interference on the battlefield, laser fuzes have become a promising candidate for application in munition systems. However, as the short-pulse laser is activated by an electrical signal, the possibility of accidental emissions caused by logic device failure cannot be ruled out, making it vulnerable under the effects of strong electromagnetic coupling. Integrating an encrypted, MEMS-based Safety and Arming Device (SAD) into the energy channel to control the propagation of short-pulse lasers can significantly enhance the safety level of munition systems. In the present work, the effect of MEMS SAD integration on laser propagation is investigated. The results demonstrate that the insertion of a MEMS SAD does not introduce significant attenuation of short-pulse laser propagation. A firing test is conducted using the laser-driven flyer detonator to verify the safety, charging mechanism, and function to provide a comprehensive characterization of the laser fuze. To guarantee the initiation of insensitive explosives, the coupling efficiency and laser transmission energy density of multi-mode quartz fibers are studied. Full article

(This article belongs to the Special Issue Optical and Laser Material Processing, 2nd Edition)

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Micromachines, Volume 16, Issue 12 (December 2025) – 72 articles

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