Micromachines

17 pages, 2890 KB

Open AccessArticle

Machining Micro-Error Compensation Methods for External Turning Tool Wear of CNC Machines

by Hui Zhang, Tongwei Lu, Zhijie Xia, Zhisheng Zhang and Jianxiong Zhu

Micromachines 2025, 16(10), 1143; https://doi.org/10.3390/mi16101143 - 8 Oct 2025

Tool wear detection is very important in CNC machine tool cutting. Once the tool is excessively worn, it is not only easy to cause the workpiece to be scrapped, but even to damage the machine. Therefore, common external turning tools of CNC machines [...] Read more.

Tool wear detection is very important in CNC machine tool cutting. Once the tool is excessively worn, it is not only easy to cause the workpiece to be scrapped, but even to damage the machine. Therefore, common external turning tools of CNC machines are studied. The effect of tool nose wear on machining accuracy was analyzed by a building mathematical model. According to different wear conditions, a linear detection method based on edge images and input features was proposed to detect the main and secondary cutting edges, which helped determine the theoretical center of the tool nose and build a morphological visual model. For different error cases, the axial and radial error compensation strategies were proposed, respectively. By comparing the experimental data of four kinds of workpieces before and after compensation machining, the average errors of them were reduced separately, and the maximum value reached 79.2%, which verified the effectiveness of the compensation strategy. The intelligent compensation strategies will significantly improve the micro-machining accuracy and efficiency of the external turning tools in CNC machines. Full article

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5 pages, 448 KB

Open AccessEditorial

Direct Femtosecond Laser Writing of Micro-Optical Components

by Alessandra Nardini, Rebeca Martínez Vázquez and Behjat Sadat Kariman

Micromachines 2025, 16(10), 1142; https://doi.org/10.3390/mi16101142 - 4 Oct 2025

Abstract

Direct femtosecond laser writing (DLW), also known as two-photon polymerization (2PP), emerged as a true 3D micro/nano-structuring method in 1997 when Mauro and co-workers first demonstrated infrared femtosecond laser photopolymerization of a UV-curable resist [...] Full article

(This article belongs to the Section A1: Optical MEMS and Photonic Microsystems)

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22 pages, 6737 KB

Open AccessArticle

Molecular Dynamics Study on the Effect of Surface Films on the Nanometric Grinding Mechanism of Single-Crystal Silicon

by Meng Li, Di Chang, Pengyue Zhao and Jiubin Tan

Micromachines 2025, 16(10), 1141; https://doi.org/10.3390/mi16101141 - 2 Oct 2025

Abstract

To investigate the influence of surface films on the material removal mechanism of single-crystal silicon during nanogrinding, molecular dynamics (MD) simulations were performed under different surface-film conditions. The simulations examined atomic displacements, grinding forces, radial distribution functions (RDF), phase transformations, temperature distributions, and [...] Read more.

To investigate the influence of surface films on the material removal mechanism of single-crystal silicon during nanogrinding, molecular dynamics (MD) simulations were performed under different surface-film conditions. The simulations examined atomic displacements, grinding forces, radial distribution functions (RDF), phase transformations, temperature distributions, and residual stress distributions to elucidate the damage mechanisms at the surface and subsurface on the nanoscale. In this study, boron nitride (BN) and graphene films were applied to the surface of single-crystal silicon workpieces for nanogrinding simulations. The results reveal that both BN and graphene films effectively suppress chip formation, thereby improving the surface quality of the workpiece, with graphene showing a stronger inhibitory effect on atomic displacements. Both films reduce tangential forces and mitigate grinding force fluctuations, while increasing normal forces; the increase in normal force is smaller with BN. Although both films enlarge the subsurface damage layer (SDL) thickness and exhibit limited suppression of crystalline phase transformations, they help to alleviate surface stress release. In addition, the films reduce the surface and subsurface temperatures, with graphene yielding a lower temperature. Residual stresses beneath the abrasive grain are also reduced when either film is applied. Overall, BN and graphene films can enhance the machined surface quality, but further optimization is required to minimize subsurface damage (SSD), providing useful insights for the optimization of single-crystal silicon nanogrinding processes. Full article

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20 pages, 4013 KB

Open AccessReview

Bioengineering 3D Pancreatic Cancer Models with Fibrotic Stroma for In Vitro Cancer Modeling

by Xingrun Lan, Keke Chen and Xiaoyun Wei

Micromachines 2025, 16(10), 1140; https://doi.org/10.3390/mi16101140 - 2 Oct 2025

Abstract

Pancreatic ductal adenocarcinoma (PDAC) remains highly lethal due to late diagnosis, high malignancy, and profound resistance to therapy. Traditional two-dimensional (2D) cell cultures fail to recapitulate the complex tumor microenvironment (TME), especially the fibrotic stroma, which is crucial for the progression of PDAC [...] Read more.

Pancreatic ductal adenocarcinoma (PDAC) remains highly lethal due to late diagnosis, high malignancy, and profound resistance to therapy. Traditional two-dimensional (2D) cell cultures fail to recapitulate the complex tumor microenvironment (TME), especially the fibrotic stroma, which is crucial for the progression of PDAC and drug response. In vitro three-dimensional (3D) models, which provide more physiologically relevant features such as tight cell–cell and cell-extracellular matrix (ECM) interactions, as well as 3D architecture, have been regarded as highly promising models in PDAC research. This review summarizes some representative in vitro PDAC models, including 3D spheroids, tumor-on-a-chip, bioprinted constructs, and patient-derived organoids (PDOs), particularly focused on the advances in bioengineering strategies for the integration of the key stomal components for microenvironment recapitulation and their applications. Additionally, we discuss the current challenges facing 3D models and propose potential strategies for constructing in vitro models that more accurately simulate the pathophysiology of the fibrotic stroma, aiming for their application in clinical settings. Full article

(This article belongs to the Special Issue 3D Tissue Engineering Techniques and Their Applications)

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12 pages, 1130 KB

Open AccessArticle

Experimental Study on Abrasive Flow Polishing of Grooves and Oil Holes of Aircraft Engine Main Bearing

by Qinghao Zhang, Jikun Yu and Mingyu Wu

Micromachines 2025, 16(10), 1139; https://doi.org/10.3390/mi16101139 - 1 Oct 2025

Abstract

This study addresses the challenges in machining the raceways and oil holes of aircraft engine bearing rings by conducting abrasive flow machining experiments on main bearing rings which had undergone ultra-precision grinding. Viscoelastic abrasive media containing cubic boron nitride of different particle sizes [...] Read more.

This study addresses the challenges in machining the raceways and oil holes of aircraft engine bearing rings by conducting abrasive flow machining experiments on main bearing rings which had undergone ultra-precision grinding. Viscoelastic abrasive media containing cubic boron nitride of different particle sizes is used during the experiments. The results show that bearing performance is improved significantly in terms of surface roughness and residual compressive stress consequently; the overall surface quality is raised. The machining process meets the precision requirements for the main bearings of this type of aircraft engine, validating the feasibility and effectiveness of Abrasive Flow Machining (AFM), and the foundation for further optimization of this process is set through this research. Full article

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

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28 pages, 3829 KB

Open AccessReview

Automated Platforms in C. elegans Research: Integration of Microfluidics, Robotics, and Artificial Intelligence

by Tasnuva Binte Mahbub, Parsa Safaeian and Salman Sohrabi

Micromachines 2025, 16(10), 1138; https://doi.org/10.3390/mi16101138 - 1 Oct 2025

Abstract

Caenorhabditis elegans is one of the most extensively studied model organisms in biology. Its advantageous features, including genetic homology with humans, conservation of disease pathways, transparency, short lifespan, small size and ease of maintenance have established it as a powerful system for research [...] Read more.

Caenorhabditis elegans is one of the most extensively studied model organisms in biology. Its advantageous features, including genetic homology with humans, conservation of disease pathways, transparency, short lifespan, small size and ease of maintenance have established it as a powerful system for research in aging, genetics, molecular biology, disease modeling and drug discovery. However, traditional methods for worm handling, culturing, scoring and imaging are labor-intensive, low throughput, time consuming, susceptible to operator variability and environmental influences. Addressing these challenges, recent years have seen rapid innovation spanning microfluidics, robotics, imaging platforms and AI-driven analysis in C. elegans-based research. Advances include micromanipulation devices, robotic microinjection systems, automated worm assays and high-throughput screening platforms. In this review, we first summarize foundational developments prior to 2020 that shaped the field, then highlight breakthroughs from the past five years that address key limitations in throughput, reproducibility and scalability. Finally, we discuss ongoing challenges and future directions for integrating these technologies into next-generation automated C. elegans research. Full article

(This article belongs to the Special Issue Advances in Microfluidic Chips for Chemical and Biomedical Applications)

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12 pages, 2558 KB

Open AccessArticle

Degradation and Damage Effects in GaN HEMTs Induced by Low-Duty-Cycle High-Power Microwave Pulses

by Dong Xing, Hongxia Liu, Mengwei Su, Xingjun Liu and Chang Liu

Micromachines 2025, 16(10), 1137; https://doi.org/10.3390/mi16101137 - 1 Oct 2025

Abstract

This study investigates the effects and mechanisms of high-power microwave on GaN HEMTs. By injecting high-power microwave from the gate into the device and employing techniques such as DC characteristics, gate-lag effect analysis, low-frequency noise measurement, and focused ion beam (FIB) cross-sectional inspection, [...] Read more.

This study investigates the effects and mechanisms of high-power microwave on GaN HEMTs. By injecting high-power microwave from the gate into the device and employing techniques such as DC characteristics, gate-lag effect analysis, low-frequency noise measurement, and focused ion beam (FIB) cross-sectional inspection, a systematic investigation was conducted on GaN HEMT degradation and failure behaviors under conditions of a low duty cycle and narrow pulse width. Experimental results indicate that under relatively low-power HPM stress, GaN HEMT exhibits only a slight threshold voltage shift and a modest increase in transconductance, attributed to the passivation of donor-like defects near the gate. However, when the injected power exceeds 43 dBm, the electric field beneath the gate triggers avalanche breakdown, forming a leakage path and causing localized heat accumulation, which ultimately leads to permanent device failure. This study reveals the physical failure mechanisms of GaN HEMTs under low-duty-cycle HPM stress and provides important guidance for the reliability design and hardening protection of RF devices. Full article

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

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19 pages, 19265 KB

Open AccessArticle

A Novel Microfluidic Platform for Circulating Tumor Cell Identification in Non-Small-Cell Lung Cancer

by Tingting Tian, Shanni Ma, Yan Wang, He Yin, Tiantian Dang, Guangqi Li, Jiaming Li, Weijie Feng, Mei Tian, Jinbo Ma and Zhijun Zhao

Micromachines 2025, 16(10), 1136; https://doi.org/10.3390/mi16101136 - 1 Oct 2025

Abstract

Circulating tumor cells (CTCs) are crucial biomarkers for lung cancer metastasis and recurrence, garnering significant clinical attention. Despite this, efficient and cost-effective detection methods remain scarce. Consequently, there is an urgent demand for the development of highly sensitive CTC detection technologies to enhance [...] Read more.

Circulating tumor cells (CTCs) are crucial biomarkers for lung cancer metastasis and recurrence, garnering significant clinical attention. Despite this, efficient and cost-effective detection methods remain scarce. Consequently, there is an urgent demand for the development of highly sensitive CTC detection technologies to enhance lung cancer diagnosis and treatment. This study utilized microspheres and A549 cells to model CTCs, assessing the impact of acoustic field forces on cell viability and proliferation and confirming capture efficiency. Subsequently, CTCs from the peripheral blood of patients with lung cancer were captured and identified using fluorescence in situ hybridization, and the results were compared to the immunomagnetic bead method to evaluate the differences between the techniques. Finally, epidermal growth factor receptor (EGFR) mutation analysis was conducted on CTC-positive samples. The findings showed that acoustic microfluidic technology effectively captures microspheres, A549 cells, and CTCs without compromising cell viability or proliferation. Moreover, EGFR mutation analysis successfully identified mutation types in four samples, establishing a basis for personalized targeted therapy. In conclusion, acoustic microfluidic technology preserves cell viability while efficiently capturing CTCs. When integrated with EGFR mutation analysis, it provides robust support for the precise diagnosis and treatment of lung cancer as well as personalized drug therapy. Full article

(This article belongs to the Special Issue Application of Microfluidic Technology in Bioengineering)

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12 pages, 1377 KB

Open AccessArticle

Research on Radiation-Hardened RCC Isolated Power Supply for High-Radiation-Field Applications

by Xiaojin Lu, Hong Yin, Youran Wu, Lihong Zhu, Ke Hong, Qifeng He, Ziyu Zhou and Gang Dong

Micromachines 2025, 16(10), 1135; https://doi.org/10.3390/mi16101135 - 30 Sep 2025

Abstract

A radiation-hardened RCC (Ring Choke Converter) isolated power supply design is proposed, which provides an innovative solution to the challenge of providing stable power to the PWM controller in DC-DC converters under nuclear radiation environments. By optimizing circuit architecture and component selection, and [...] Read more.

A radiation-hardened RCC (Ring Choke Converter) isolated power supply design is proposed, which provides an innovative solution to the challenge of providing stable power to the PWM controller in DC-DC converters under nuclear radiation environments. By optimizing circuit architecture and component selection, and incorporating transformer isolation and dynamic parameter compensation technology, the RCC maintains an 8.9 V output voltage after exposure to neutron irradiation of 3 × 10¹³ n/cm², significantly outperforming conventional designs with a failure threshold of 1 × 10¹³ n/cm². For the first time, the degradation mechanisms of VDMOS devices under neutron irradiation during switching operations are systematically revealed: a 32–36% reduction in threshold voltage (with the main power transistor dropping from 5 V to 3.4 V) and an increase in on-resistance. Based on these findings, a selection criterion for power transistors is established, enabling the power supply to achieve a 2 W output in extreme environments such as nuclear power plant monitoring and satellite systems. The results provide a comprehensive solution for radiation-hardened power electronics systems, covering device characteristic analysis to circuit optimization, with significant engineering application value. Full article

(This article belongs to the Special Issue Recent Advances in Field-Effect Transistors: Materials, Devices, and Emerging Applications)

17 pages, 2721 KB

Open AccessArticle

Physics-Guided Neural Surrogate Model with Particle Swarm- Based Multi-Objective Optimization for Quasi-Coaxial TSV Interconnect Design

by Zheng Liu, Guangbao Shan, Zeyu Chen and Yintang Yang

Micromachines 2025, 16(10), 1134; https://doi.org/10.3390/mi16101134 - 30 Sep 2025

Abstract

In reconfigurable radio frequency (RF) microsystems, the interconnect structure critically affects high-frequency signal integrity, and the accuracy of electromagnetic (EM) modeling directly determines the overall system performance. Conventional neural network-based surrogate models mainly focus on minimizing numerical errors, while neglecting essential physical constraints, [...] Read more.

In reconfigurable radio frequency (RF) microsystems, the interconnect structure critically affects high-frequency signal integrity, and the accuracy of electromagnetic (EM) modeling directly determines the overall system performance. Conventional neural network-based surrogate models mainly focus on minimizing numerical errors, while neglecting essential physical constraints, such as causality and passivity, thereby limiting their applicability in both time and frequency domains. This paper proposes a physics-constrained Neuro-Transfer surrogate model with a broadband output architecture to directly predict S-parameters over the 1–50 GHz range. Causality and passivity are enforced through dedicated regularization terms during training. Furthermore, a particle swarm optimization (PSO)-based multi-objective intelligent optimization framework is developed, incorporating fixed-weight normalization and a linearly decreasing inertia weight strategy to simultaneously optimize the S11, S21, and S22 performance of a quasi-coaxial TSV composite structure. Target values are set to −25 dB, −0.54 dB, and −24 dB, respectively. The optimized structural parameters yield prediction-to-simulation deviations below 1 dB, with an average prediction error of 2.11% on the test set. Full article

(This article belongs to the Special Issue Flexible and Biodegradable Electronics and Novel Semiconductor Devices)

12 pages, 3386 KB

Open AccessArticle

Effect of Grain Size on Polycrystalline Copper Finish Quality of Ultra-Precision Cutting

by Chuandong Zhang, Xinlei Yue, Kaiyuan You and Wei Wang

Micromachines 2025, 16(10), 1133; https://doi.org/10.3390/mi16101133 - 30 Sep 2025

Abstract

Polycrystalline copper optics are widely utilized in infrared systems due to their exceptional electrical and thermal conductivity combined with favorable machining characteristics. The grain size profoundly influences both surface quality consistency and fundamental material removal behavior during processing. This investigation employs multiscale numerical [...] Read more.

Polycrystalline copper optics are widely utilized in infrared systems due to their exceptional electrical and thermal conductivity combined with favorable machining characteristics. The grain size profoundly influences both surface quality consistency and fundamental material removal behavior during processing. This investigation employs multiscale numerical modeling to simulate nanoscale cutting processes in polycrystalline copper with controlled grain structures, coupled with experimental ultra-precision machining validation. Comprehensive analysis of stress distribution, subsurface damage formation, and cutting force evolution reveals that refined grain structures promote more homogeneous plastic deformation, resulting in superior surface finish with reduced roughness and diminished grain boundary step formation. However, the enhanced grain boundary density in fine-grained specimens necessitates increased cutting energy input. These findings establish critical process–structure–property relationships essential for advancing precision manufacturing of copper-based optical systems. Full article

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

12 pages, 4545 KB

Open AccessArticle

Wearable Flexible Wireless Pressure Sensor Based on Poly(vinyl alcohol)/Carbon Nanotube/MXene Composite for Health Monitoring

by Lei Zhang, Junqi Pang, Xiaoling Lu, Xiaohai Zhang and Xinru Zhang

Micromachines 2025, 16(10), 1132; https://doi.org/10.3390/mi16101132 - 30 Sep 2025

Abstract

Accurate pressure monitoring is crucial for both human body applications and intelligent robotic arms, particularly for whole-body motion monitoring in human–machine interfaces. Conventional wearable electronic devices, however, often suffer from rigid connections, non-conformity, and inaccuracies. In this study, we propose a high-precision wireless [...] Read more.

Accurate pressure monitoring is crucial for both human body applications and intelligent robotic arms, particularly for whole-body motion monitoring in human–machine interfaces. Conventional wearable electronic devices, however, often suffer from rigid connections, non-conformity, and inaccuracies. In this study, we propose a high-precision wireless flexible sensor using a poly(vinyl alcohol)/single-walled carbon nanotube/MXene composite as the sensitive material, combined with a randomly distributed wrinkle structure to accurately monitor pressure parameters. To validate the sensor’s performance, it was used to monitor movements of the vocal cords, bent fingers, and human pulse. The sensor exhibits a pressure measurement range of approximately 0–130 kPa and a minimum resolution of 20 Pa. At pressures below 1 kPa, the sensor exhibits high sensitivity, enabling the detection of transient pressure changes. Within the pressure range of 1–10 kPa, the sensitivity decreases to approximately 54.71 kPa⁻¹. Additionally, the sensor demonstrates response times of 12.5 ms at 10 kPa. For wireless signal acquisition, the pressure sensor was integrated with a Bluetooth chip, enabling real-time high-precision pressure monitoring. A deep learning-based training model was developed, achieving over 98% accuracy in motion recognition without additional computing equipment. This advancement is significant for streamlined human motion monitoring systems and intelligent components. Full article

(This article belongs to the Special Issue Advanced Micro- and Nano-Manufacturing Technologies for Flexible Electronics)

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15 pages, 2358 KB

Open AccessArticle

Toward Thermally Stimuli-Responsive Polymeric Vesicles Fabricated by Block Copolymer Blends for Nanocarriers

by Jun-Ki Lee, Seung-Bum Heo, Jong Dae Jang, Dong-Chul Yang, Dae-Hee Yoon, Changwoo Do and Tae-Hwan Kim

Micromachines 2025, 16(10), 1131; https://doi.org/10.3390/mi16101131 - 30 Sep 2025

Abstract

Polymeric vesicles, characterized by enhanced colloidal stability, excellent mechanical properties, controllable surface functionality, and adjustable membrane thickness, are extremely useful in nano- and bio-technology for potential applications as nanosized carriers for drugs and enzymes. However, a few preparative steps are necessary to achieve [...] Read more.

Polymeric vesicles, characterized by enhanced colloidal stability, excellent mechanical properties, controllable surface functionality, and adjustable membrane thickness, are extremely useful in nano- and bio-technology for potential applications as nanosized carriers for drugs and enzymes. However, a few preparative steps are necessary to achieve a unilamellar vesicle with a narrow size distribution. Herein, we report the spontaneous formation of unilamellar polymeric vesicles with nanometer sizes (<50 nm), fabricated by simply mixing diblock copolymers (P(EO-AGE)(2K-2K) and P(EO-AGE)(0.75K-2K)) with differing hydrophilic mass fractions in aqueous solutions. Depending on the mixing ratio of block copolymers and the temperature, the block copolymer mixtures self-assemble into various nanostructures, such as spherical and cylindrical micelles, or vesicles. The self-assembled structures of the block copolymer mixtures were characterized by small-angle neutron scattering, resulting in a phase diagram drawn as a function of temperature and the mixing condition. Notably, the critical temperature for the micelle-to-vesicle phase transition can be easily controlled by altering the mixing conditions; it decreases with an increase in the concentration of one of the block copolymers. Full article

(This article belongs to the Section B5: Drug Delivery System)

28 pages, 4284 KB

Open AccessReview

Advances in Silicon-Based UV Light Detection

by Arif Kamal, Seongin Hong and Heongkyu Ju

Micromachines 2025, 16(10), 1130; https://doi.org/10.3390/mi16101130 - 30 Sep 2025

Abstract

Silicon (Si), the cornerstone semiconductor in the micro-electronics industry, can provide a cost-efficient platform with mature technologies for photodetection in visible and near-infrared regions. However, its intrinsic properties, such as a narrow bandgap and the shallow penetration depth of ultraviolet (UV) light into [...] Read more.

Silicon (Si), the cornerstone semiconductor in the micro-electronics industry, can provide a cost-efficient platform with mature technologies for photodetection in visible and near-infrared regions. However, its intrinsic properties, such as a narrow bandgap and the shallow penetration depth of ultraviolet (UV) light into its surface with surface trap states, remain challenges, rendering it unsuitable for effective UV light detection. Various techniques have been reported to circumvent these surface defect-induced difficulties. In addition, wide-bandgap semiconductors that favor UV light absorption in a solar-blind way have been combined with Si for UV light detection in order to retain the device’s compatibility with Si-CMOS processes, though it still faces challenges that need to be overcome. This review starts with concepts of basic parameters of photodetectors and categorizes UV photodetectors according to their detection mechanisms. We also present a review of wide-bandgap semiconductor-based UV light detectors and those based on Si, with a discussion of surface defect minimization. In addition, we review the hybrid structure of the two kinds, i.e., wide-bandgap semiconductors and Si, and discuss their properties that produce synergistic effects. Lastly, we provide conclusions and outlooks for the possible development of next-generation UV light detectors based on Si. Full article

(This article belongs to the Special Issue Photodetectors and Their Applications)

12 pages, 2886 KB

Open AccessArticle

Atomic-Scale Revelation of Voltage-Modulated Electrochemical Corrosion Mechanism in 4H-SiC Substrate

by Qiufa Luo, Dianlong Lin, Jing Lu, Congming Ke, Zige Tian, Feng Jiang, Jianhui Zhu and Hui Huang

Micromachines 2025, 16(10), 1129; https://doi.org/10.3390/mi16101129 - 30 Sep 2025

Abstract

Electrochemical mechanical polishing is a critical technology for improving the surface quality of silicon carbide (SiC) substrates. However, the fundamental electrochemical corrosion mechanism of the SiC substrate remains incompletely understood. In this study, the electrochemical corrosion behavior of the SiC substrate is explored [...] Read more.

Electrochemical mechanical polishing is a critical technology for improving the surface quality of silicon carbide (SiC) substrates. However, the fundamental electrochemical corrosion mechanism of the SiC substrate remains incompletely understood. In this study, the electrochemical corrosion behavior of the SiC substrate is explored through comprehensive experiments and molecular dynamics simulations. Key findings demonstrated that the 4H-0° SiC exhibited the highest corrosion rate in a 0.6 mol/L NaCl electrolyte. The corrosion rate increased as the voltage rose within the range of 2 to 20 V. When the voltage was between 20 and 25 V, the system entered the stable passivation region, while when the voltage was 25 to 30 V, partial dissolution of the surface oxide layer occurred. Molecular dynamics simulations further revealed that both amorphization degree and reaction depth on the SiC surface showed a decreasing trend at elevated voltages, suggesting a corresponding reduction in the corrosion rate when the voltage exceeded the optimal range. OH⁻, O²⁻, and •OH generated by the electrolysis of water during electrochemical corrosion would rapidly react with the surface of the SiC anode, and subsequently form a SiO₂ modified layer. Moreover, these atomistic insights establish a scientific foundation for achieving superior surface integrity in large-diameter SiC substrates through optimized electrochemical mechanical polishing processes. Full article

(This article belongs to the Special Issue Ultra-Precision Surface Abrasive Micro-Machining: Advances and Applications)

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20 pages, 7171 KB

Open AccessArticle

Research on a Phase-Shift-Based Discontinuous PWM Method for 24V Onboard Thermally Limited Micro Voltage Source Inverters

by Shuo Wang and Chenyang Xia

Micromachines 2025, 16(10), 1128; https://doi.org/10.3390/mi16101128 - 30 Sep 2025

Abstract

This research explores a phase-shift-based discontinuous PWM method used for 24 V battery-powered onboard micro inverters, which are critical for thermally limited applications like micromachines, where efficient heat dissipation and compact size are paramount. Discontinuous pulse width modulation (DPWM) reduces switching losses by [...] Read more.

This research explores a phase-shift-based discontinuous PWM method used for 24 V battery-powered onboard micro inverters, which are critical for thermally limited applications like micromachines, where efficient heat dissipation and compact size are paramount. Discontinuous pulse width modulation (DPWM) reduces switching losses by clamping the phase voltage to the DC bus in order to improve inverter efficiency. Due to the change in power factor at different operating points from motors or the inductor load, the use of only one DPWM method cannot achieve the optimal efficiency of a three-phase voltage source inverter (3ph-VSI). This paper proposes a generalized DPWM method with a continuously adjustable phase shift angle, which extends the six traditional DPWM methods to any type. According to different power factors, the proposed DPWM method is divided into five power factor angle intervals, namely [−90°, −60°], [−60°, −30°], [−30°, 30°], [30°, 60°], and [60°, 90°], and automatically adjusts the phase shift angle to the optimal-efficiency DPWM mode. The power factor is calculated by means of the Synchronous Reference Frame Phase-Locked Loop (SRF-PLL) method. The switching losses and harmonic characteristics of the proposed DPWM are analyzed, and finally, a 24 V onboard 3ph-VSI experimental platform is built. The experimental results show that the efficiency of DPWM methods can be improved by 3–6% and the switching loss can be reduced by 40–50% under different power factors. At the same time, the dynamic performance of the proposed algorithm with a transition state is verified. This method is particularly suitable for miniaturized inverters where efficiency and thermal management are critical. Full article

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27 pages, 4563 KB

Open AccessReview

Principles of Operation and Application Extensions of Triboelectric Nanogenerators: Structure and Material Optimization

by Li Tao, Tianyu Chen, Jiale Wu, Teng Zhang, Lei Shao, Haoliang Zhang, Litao Liu, Hongbo Wu, Tao Chen and Jingdong Ji

Micromachines 2025, 16(10), 1127; https://doi.org/10.3390/mi16101127 - 30 Sep 2025

Abstract

As research on triboelectric nanogenerators (TENGs) continues to advance, their applications are becoming increasingly diverse and sophisticated. This paper aims to provide future researchers with a concise yet comprehensive understanding of the four fundamental operational principles of TENGs, enabling them to fully appreciate [...] Read more.

As research on triboelectric nanogenerators (TENGs) continues to advance, their applications are becoming increasingly diverse and sophisticated. This paper aims to provide future researchers with a concise yet comprehensive understanding of the four fundamental operational principles of TENGs, enabling them to fully appreciate the unique characteristics and application scenarios of each mode. In doing so, researchers can make informed and well-grounded choices in selecting the most suitable operational mode for exploration and innovation, tailored to their specific fields and requirements. Furthermore, this paper aligns closely with the current research frontiers and development trends of TENGs by systematically reviewing the literature and analyzing recent developments in the field from three key perspectives: the expansion of application domains, innovations in structural design, and optimizations in material properties. Through this multidimensional framework, it not only highlights the broad potential and practical prospects of TENGs but also uncovers the latest advancements and future directions in technological breakthroughs and performance enhancement. Full article

14 pages, 4404 KB

Open AccessArticle

The Influence of Pulsed Superimposed DC Electric Field Synergistically Inducing Orientation Arrangement of BNNSs on Thermal Properties of Epoxy Composites

by Xiaopeng Wang, Songyuan Li, Zhen Yin, Qi Zhang, Lei Deng, Yiqin Peng and Yan Mi

Micromachines 2025, 16(10), 1126; https://doi.org/10.3390/mi16101126 - 30 Sep 2025

Abstract

Modern power systems require better heat dissipation and thermal stability, but traditional low-filler composites cannot significantly enhance thermal conductivity. To address this issue, electric field induction technology orientation can efficiently orient boron nitride nanosheets (BNNSs), thereby improving the thermal conductivity of epoxy composites [...] Read more.

Modern power systems require better heat dissipation and thermal stability, but traditional low-filler composites cannot significantly enhance thermal conductivity. To address this issue, electric field induction technology orientation can efficiently orient boron nitride nanosheets (BNNSs), thereby improving the thermal conductivity of epoxy composites composed of BNNSs as the thermally conductive filler. In this study, an innovative approach employing a pulsed superimposed direct current (DC) electric field to synergistically induce filler orientation is used to construct efficient thermally conductive channels. The study found that the thermal conductivity of the composite prepared by superimposing an 8 kV/mm pulsed electric field on a 30 V/mm DC electric field is about 0.474 W/(m·K), which is 34.66% higher than that prepared by only a pulsed-induced field and 17.5% higher than the theoretical superposition value. Similarly, the composite prepared by superimposing a 4 kV/mm pulsed electric field on a 70 V/mm DC electric field increased to about 0.464 W/(m·K), which is 27.47% higher than that prepared by only a DC-induced field and 12.4% higher than the theoretical superposition value. These results indicate that the superimposed electric field treatment synergistically improves the thermal conductivity of the composite. Compared to other materials, composites prepared using the superimposed pulsed and DC electric field induction also exhibit superior thermal stability. This strategy effectively addresses the issue of material thermal aging caused by insufficient thermal conductivity, providing innovative ideas and a solid theoretical foundation for material design and thermal management. Full article

(This article belongs to the Special Issue Low-Dimensional Materials and Applications in Electronics)

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27 pages, 981 KB

Open AccessReview

Organ-on-a-Chip Models of the Female Reproductive System: Current Progress and Future Perspectives

by Min Pan, Huike Chen, Kai Deng and Ke Xiao

Micromachines 2025, 16(10), 1125; https://doi.org/10.3390/mi16101125 - 30 Sep 2025

Abstract

The female reproductive system represents a highly complex regulatory network governing critical physiological functions, encompassing reproductive capacity and endocrine regulation that maintains female physiological homeostasis. The in vitro simulation system provides a novel tool for biomedical research and can be used as physiological [...] Read more.

The female reproductive system represents a highly complex regulatory network governing critical physiological functions, encompassing reproductive capacity and endocrine regulation that maintains female physiological homeostasis. The in vitro simulation system provides a novel tool for biomedical research and can be used as physiological and pathological models to study the female reproductive system. Recent advances in this technology have evolved from 2D and 3D printing to organ-on-a-chip (OOC) and microfluidic systems, which has emerged as a transformative platform for modeling the female reproductive system. These microphysiological systems integrate microfluidics, 3D cell culture, and biomimetic scaffolds to replicate key functional aspects of reproductive organs and tissues. They have enabled precise simulation of hormonal regulation, embryo-endometrium interactions, and disease mechanisms such as endometriosis and gynecologic cancers. This review highlights the current state of female reproductive OOCs, including ovary-, uterus-, and fallopian tube-on-a-chip system, their applications in assisted reproduction and disease modeling, and the technological hurdles to their widespread application. Though significant barriers remain in scaling OOCs for high-throughput drug screening, standardizing protocols for clinical applications, and validating their predictive value against human patient outcomes, OOCs have emerged as a transformative platform to model complex pathologies, offering unprecedented insights into disease mechanisms and personalized therapeutic interventions. Future directions, including multi-organ integration for systemic reproductive modeling, incorporation of microbiome interactions, and clinical translation for mechanisms of drug action, will facilitate unprecedented insights into reproductive physiology and pathology. Full article

(This article belongs to the Special Issue Microfluidics in Biomedical Research)

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