Micromachines

14 pages, 4151 KB

Open AccessArticle

Soft-Error-Resilient Static Random Access Memory with Enhanced Write Ability for Radiation Environments

by Se-Yeon Park, Eun Gyo Jeong and Sung-Hun Jo

Micromachines 2025, 16(11), 1212; https://doi.org/10.3390/mi16111212 (registering DOI) - 24 Oct 2025

As semiconductor technologies advance, SRAM cells deployed in space systems face heightened sensitivity to radiation-induced soft errors. In conventional 6T SRAM, when high-energy particles strike sensitive nodes, single-event upsets (SEUs) may occur, flipping stored bits. Furthermore, with aggressive scaling, charge sharing among adjacent [...] Read more.

As semiconductor technologies advance, SRAM cells deployed in space systems face heightened sensitivity to radiation-induced soft errors. In conventional 6T SRAM, when high-energy particles strike sensitive nodes, single-event upsets (SEUs) may occur, flipping stored bits. Furthermore, with aggressive scaling, charge sharing among adjacent devices can trigger single-event multi-node upsets (SEMNU). To address these reliability concerns, this study presents a radiation-hardened SRAM design, SHWA18T, tailored for space applications. The proposed architecture is evaluated against IASE16T, PRO14T, PRO16T, QCCS, SIRI, and SEA14T. Simulation analysis demonstrates that SHWA18T achieves improved performance, particularly in terms of critical charge and write capability. The design was implemented in 90 nm CMOS technology at a 1 V supply. With enhanced robustness, the cell withstands both SEUs and SEMNUs, thereby guaranteeing stable data retention in space environments. Full article

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

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14 pages, 7812 KB

Open AccessArticle

Study on Microstructures and Properties of FeCoNiCuAlSi_x High-Entropy Alloy Composite Coatings by Laser Cladding

by Xinyu Zhang, Chun Guo, Guangcan Huang, Zheng Peng, Ruizhang Hu, Qingcheng Lin and Tianyuan Lu

Micromachines 2025, 16(11), 1211; https://doi.org/10.3390/mi16111211 (registering DOI) - 24 Oct 2025

Abstract

FeCoNiCuAl high-entropy alloys exhibit remarkable mechanical properties; nevertheless, these materials struggle to withstand harsh environments because of their insufficient resistance to wear and corrosion. The addition of Si can significantly enhance the alloy’s high-temperature performance, hardness, and wear resistance, thereby making it more [...] Read more.

FeCoNiCuAl high-entropy alloys exhibit remarkable mechanical properties; nevertheless, these materials struggle to withstand harsh environments because of their insufficient resistance to wear and corrosion. The addition of Si can significantly enhance the alloy’s high-temperature performance, hardness, and wear resistance, thereby making it more suitable for applications in high-temperature or corrosive environments. To overcome these drawbacks, this research investigates how varying Si content affects the microstructure and properties of FeCoNiCuAl coatings. Composite coatings of FeCoNiCuAlSi_x (x = 0, 0.5, 1.0, 1.5, 2.0) were fabricated on 65 Mn substrates using laser cladding. Various testing methods, including metallographic microscopy, Vickers hardness testing, friction and wear testing, and electrochemical analysis, were employed to examine the phase structure, microstructure, and hardness of the coating. It is observed that the FeCoNiCuAl coating begins with a uniform FCC phase structure. However, as the Si content increases, a phase transformation to the BCC structure occurs. The microstructure is primarily composed of isometric crystals and dendrites that become finer and more compact with higher Si content. For the FeCoNiCuAlSi_2.0 coating, the microhardness reaches 581.05 HV_0.2. Additionally, wear resistance shows a positive correlation with Si content. Electrochemical testing in NS4 solution shows that the corrosion potential of the coating increases from −0.471 V for FeCoNiCuAl to −0.344 V for FeCoNiCuAlSi_2.0, while the corrosion current density decreases from 1.566 × 10⁻⁶ A/cm² to 4.073 × 10⁻⁶ A/cm². These results indicate that Si addition plays a crucial role in enhancing the mechanical properties and corrosion resistance of FeCoNiCuAl coatings, making them more suitable for high-performance applications in extreme environments. Full article

(This article belongs to the Special Issue Future Prospects of Additive Manufacturing, 2nd Edition)

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14 pages, 5284 KB

Open AccessArticle

Impact of Phase Defects on the Aerial Image in High NA Extreme Ultraviolet Lithography

by Kun He and Zhinan Zeng

Micromachines 2025, 16(11), 1210; https://doi.org/10.3390/mi16111210 - 24 Oct 2025

Abstract

With the development of extreme ultraviolet (EUV) lithography technology to higher numerical aperture (NA), it provides higher resolution imaging quality, which may be more sensitive to the phase defect in EUV mask. Therefore, it is necessary to comprehensively understand the effect of phase [...] Read more.

With the development of extreme ultraviolet (EUV) lithography technology to higher numerical aperture (NA), it provides higher resolution imaging quality, which may be more sensitive to the phase defect in EUV mask. Therefore, it is necessary to comprehensively understand the effect of phase defect on the imaging quality depending on the NA. We simulated aerial images of patterned EUV masks for the EUV lithography exposure tool of NA = 0.55 and NA = 0.33 using the rigorous coupled-wave analysis (RCWA) method. The results shows that higher NA enhances the contrast of aerial images, which, in turn, provides greater tolerance for phase defect. This indicates that high NA can mitigate the negative impact of phase defect on imaging quality to some extent. Furthermore, it is found that both the defect signal and the intensity loss ratio of the aerial image first increase and then decrease as the width of the phase defect increases, due to the height/width ratio of the phase defect. Meanwhile, the defect width corresponding to the maximum phase defect signal tends to become smaller as the NA becomes larger. It is also worth noting that when NA = 0.33, variations in the position of the phase defect led to fluctuations in the CD error due to the shadow effect of the absorber, while it diminishes at NA = 0.55. This is because a higher NA of 0.55 provides a stronger background field, which suppresses the shadow effect of the absorber more effectively than it does at NA = 0.33. Full article

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

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16 pages, 7998 KB

Open AccessArticle

A Wideband Multi-Polarized Microstrip Antenna with High Polarization Isolation Based on Dual-Circular Polarization

by Xuenan Wang, Hongcheng Zhou, Xinhui Wang, Xia Lei, Boyang Hao, Mian Zhong and Chao Zhou

Micromachines 2025, 16(11), 1209; https://doi.org/10.3390/mi16111209 - 24 Oct 2025

Abstract

To address the limited overlapping bandwidth across polarization modes in conventional multi-polarized antennas, this paper proposes a wideband multi-polarized microstrip antenna with high polarization isolation. Based on the theory of orthogonal dual-circular polarization synthesis, the proposed antenna achieves left-hand circular polarization (LHCP) and [...] Read more.

To address the limited overlapping bandwidth across polarization modes in conventional multi-polarized antennas, this paper proposes a wideband multi-polarized microstrip antenna with high polarization isolation. Based on the theory of orthogonal dual-circular polarization synthesis, the proposed antenna achieves left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) under a single-port excitation mode, and can generate arbitrary linear polarization (LP) by simply adjusting the phase when dual-fed. For verification, a prototype operating at the C-band is designed, fabricated, and measured. The measured results agree well with the simulations. For linear polarization, the measured 10 dB bandwidth ranges from 4 GHz to 8 GHz (relative bandwidth of 66.7%), with polarization isolation exceeding 26 dB. For circular polarization, the measured bandwidth (for 10 dB return loss and 3 dB axial ratio) spans 4.1–8 GHz (relative bandwidth of 64.5%), with polarization isolation greater than 15 dB. The linear polarization gain is slightly higher than the circular polarization gain, with a maximum gain of 4.3 dB. The proposed antenna simultaneously features multi-polarization, a wide bandwidth, a low profile (0.03 λ₀), and high polarization isolation, which can meet the urgent demand for multi-polarized antennas in modern multi-functional integrated wireless systems, such as communication systems, radar, and unmanned aerial vehicles (UAVs). Full article

(This article belongs to the Special Issue Integration of MEMS, 3D Printing, and Nano-Enabled Technologies in Wireless Communication and Sensing Systems)

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14 pages, 3279 KB

Open AccessArticle

An Integrated Microfluidic System for One-Stop Multiplexed Exosomal PD-L1 and MMP9 Automated Analysis with Deep Learning Model YOLO

by Yunxing Lu, Wenjing Zhang, Qiang Shi, Jianan Hui, Jieyu Wang, Yiman Song and Xiaoyue Yang

Micromachines 2025, 16(11), 1208; https://doi.org/10.3390/mi16111208 - 24 Oct 2025

Abstract

While immune escape and physical invasion are two key pathways in tumor development, traditional methods for analyzing their exosomal markers are often complex and face identification bias. Microfluidic technology offers significant advantages for non-invasive liquid biopsy, particularly in the analysis of tumor progression [...] Read more.

While immune escape and physical invasion are two key pathways in tumor development, traditional methods for analyzing their exosomal markers are often complex and face identification bias. Microfluidic technology offers significant advantages for non-invasive liquid biopsy, particularly in the analysis of tumor progression markers carried by exosomes. Here, we developed an integrated microfluidic system for the sensitive, accurate, totally on-chip exosome isolation and automatic quantification of tumor progression markers PD-L1 and MMP9. This platform leverages microfluidic design principles for efficient sample mixing and monodisperses microbeads for precise analysis, allowing for complete processing within 40 min. The system’s high efficiency and precision are further enhanced by a lightweight YOLOv5-based positional migration strategy that automates fluorescence quantification. Validation using four different cell lines demonstrated distinct exosomal protein signatures with a low detection limit of 12.58 particles/μL. This innovative microfluidic chip provides a sensitive and easy-to-handle tool for exosomal marker analysis, holding great potential for cancer identification and personalized therapy guidance in the era of point-of-care testing (POCT). Full article

(This article belongs to the Special Issue Microfluidic Systems for Biomedical Analysis, Detection and Diagnosis—Second Edition)

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17 pages, 3501 KB

Open AccessArticle

Analysis of Dynamic Stability Control of Light Source in Immersion DUV Lithography

by Yihua Zhu, Dandan Han, Chuang Wu, Sen Deng and Yayi Wei

Micromachines 2025, 16(11), 1207; https://doi.org/10.3390/mi16111207 - 23 Oct 2025

Abstract

Immersion deep ultraviolet (DUV) lithography remains an indispensable core technology in advanced integrated circuit manufacturing, particularly when combined with multiple patterning techniques to achieve sub-10 nm feature patterning. However, at advanced technology nodes, dynamic instabilities of DUV light sources—including spectral characteristics (bandwidth fluctuations, [...] Read more.

Immersion deep ultraviolet (DUV) lithography remains an indispensable core technology in advanced integrated circuit manufacturing, particularly when combined with multiple patterning techniques to achieve sub-10 nm feature patterning. However, at advanced technology nodes, dynamic instabilities of DUV light sources—including spectral characteristics (bandwidth fluctuations, and center wavelength drift), coherence variations, and pulse-to-pulse energy instability—can adversely affect imaging contrast, normalized image log-slope (NILS), and critical dimension (CD) uniformity. To quantitatively assess the impact of laser parameter fluctuations on NILS and CD, this work establishes systematic physical models for imaging perturbations caused by multi-parameter laser output instabilities under immersion DUV lithography. Through simulations, we evaluate the influence of laser parameter variations on the imaging fidelity of representative line/space (L/S) and tip-to-line (T2L) structures, thereby validating the proposed perturbation model. Research demonstrates that the spectral attributes (bandwidth fluctuation and center wavelength drift), coherence variations, and pulse energy instability collectively induce non-uniform electric field intensity distribution within photoresist, degrading NILS, and amplifying CD variation, which ultimately compromise pattern fidelity and chip yield. Notably, at advanced nodes, pulse energy fluctuation exerts a significantly greater influence on imaging errors compared to bandwidth and wavelength variations. To satisfy the 10% process window requirement for 45 nm linewidths, pulse energy fluctuations should be rigorously confined within 1%. This research provides theoretical foundations and practical insights for the design of dynamic stability control of light source and process optimization of next-generation DUV light sources. Full article

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

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12 pages, 2632 KB

Open AccessArticle

Reconfigurable Dual-Band SIW Bandpass Filter with Tunable Passbands and Enhanced Stopband Suppression

by Yongchae Jeong and Phanam Pech

Micromachines 2025, 16(11), 1206; https://doi.org/10.3390/mi16111206 - 23 Oct 2025

Abstract

This paper presents a design approach for a dual-band substrate-integrated waveguide (SIW) bandpass filter (BPF) featuring passband tunability and wide-stopband characteristics. The proposed circuit is realized using half-mode (HM) SIW cavities loaded with tunable stopband resonators (TSRs). The TSRs are realized using transmission [...] Read more.

This paper presents a design approach for a dual-band substrate-integrated waveguide (SIW) bandpass filter (BPF) featuring passband tunability and wide-stopband characteristics. The proposed circuit is realized using half-mode (HM) SIW cavities loaded with tunable stopband resonators (TSRs). The TSRs are realized using transmission lines and varactor diodes. Passband tunability can be achieved by adjusting the supply voltage on the varactor diode. Wide-stopband characteristics can be achieved by integrating the defected microstrip structure into the proposed circuit. To validate the proposed concept, dual-band HM SIW BPFs with fixed and tunable passbands has been designed and fabricated. Based on the measurement results, the proposed circuits demonstrate high-frequency selectivity, with an attenuation level better than 20 dB and measured up to more than 40 GHz at the highest stopband. Moreover, the proposed tunable dual-band HM SIW BPF provides a passband tuning range of 240 MHz, measured from 4.88 GHz to 5.12 GHz for the first passband, and 310 MHz, measured from 6.19 GHz to 6.5 GHz for the second passband. Within the passband tuning range, the insertion loss varied from 1.7 dB to 2.2 dB for the first passband and 2.1 dB to 2.5 dB for the second passband. Full article

(This article belongs to the Special Issue RF Devices: Technology and Progress)

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19 pages, 4894 KB

Open AccessArticle

Study on Microdroplets Generation and Detection Method in Four-Way Microfluid Structure (FWMS) by Double Photoresist Method Pulses

by Lele Luo and Lu Zhang

Micromachines 2025, 16(11), 1205; https://doi.org/10.3390/mi16111205 - 23 Oct 2025

Abstract

Hundred-micron-sized microdroplets are widely used in microbial culture, chemical investigations and industrial processes. The size, velocity and frequency of microdroplets significantly affect the cultivation and processing effects. The detections of droplets mainly rely on capacitance detection or imaging, but it requires expensive and [...] Read more.

Hundred-micron-sized microdroplets are widely used in microbial culture, chemical investigations and industrial processes. The size, velocity and frequency of microdroplets significantly affect the cultivation and processing effects. The detections of droplets mainly rely on capacitance detection or imaging, but it requires expensive and complex systems for capacitance detection, and high-throughput imaging detections are challenging. In this study, four-way microfluid structure (FWMS) is proposed for microdroplets generation and detection. FWMS, fixed on a 3D-printed holder, is designed to generate microdroplets (100–500 µm), with optical fibers embedded to collect double photoresist method pulses of scattering light by fast-moving microdroplets. The size and volume of the microdroplets are retrieved by tracking the double pulse signal in the time sequence. In the experiments, 50 groups of microdroplets (a total of 10⁵ microdroplets) with size ranging from 100 to 450 µm were generated and detected. Compared with traditional imaging detection, this method has a better sampling rate and detection error of less than 1.42%, which can provide a simple and accurate integrated microfluid system for microdroplet generation and synchronous detection. Full article

(This article belongs to the Topic Advances in Microfluidics and Lab on a Chip Technology, 2nd Edition)

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35 pages, 3022 KB

Open AccessArticle

Preliminary Thermo-Mechanical Evaluation of Fiber Bragg Grating Sensors for Structural Monitoring: Toward Application in Generation IV Nuclear Reactors

by Rocco Contangelo, Carlo Giovanni Ferro, Andrea Bagnasco, Quentin Pouille and Andrea Mazza

Micromachines 2025, 16(11), 1204; https://doi.org/10.3390/mi16111204 - 23 Oct 2025

Abstract

The performance and longevity of next-generation nuclear reactors depend on the implementation of sensing technologies able to withstand extreme conditions. This study evaluates the performance of femtosecond-laser-inscribed Fiber Bragg Grating (fs-FBG) sensors under simulated startup low-power conditions representative of newcleo’s Generation IV [...] Read more.

The performance and longevity of next-generation nuclear reactors depend on the implementation of sensing technologies able to withstand extreme conditions. This study evaluates the performance of femtosecond-laser-inscribed Fiber Bragg Grating (fs-FBG) sensors under simulated startup low-power conditions representative of newcleo’s Generation IV Lead-cooled Fast Reactors (LFRs). The primary goal of this preliminary test phase is to validate the suitability of fs-FBG sensors for high-temperature (300 °C) and mechanical stress (16–80 MPa cyclic tensile stress) monitoring, emphasizing their reliability and accuracy. The experimental campaign involved rigorous thermal and thermo-mechanical testing, conducted in compliance with ASTM standards, to assess key performance metrics such as linearity, repeatability, and precision. The results demonstrate that fs-FBG sensors deliver consistent and reliable measurements in extreme environments, with a temperature sensitivity of 12.62 pm/°C and a displacement sensitivity of 3.95 nm/mm. These findings provide a strong basis for the use of fs-FBG sensors in Generation IV nuclear reactors, highlighting their potential as advanced tools for structural health monitoring. Full article

40 pages, 3599 KB

Open AccessFeature PaperReview

Advanced Triboelectric Nanogenerators for Smart Devices and Emerging Technologies: A Review

by Van-Long Trinh and Chen-Kuei Chung

Micromachines 2025, 16(11), 1203; https://doi.org/10.3390/mi16111203 - 23 Oct 2025

Abstract

Smart devices and emerging technologies are highly popular devices and technologies that considerably improve our daily living by reducing or replacing human workforces, treating disease, monitoring healthcare, enhancing service performance, improving quality, and protecting the natural environment, and promoting non-gas emissions, sustainable working, [...] Read more.

Smart devices and emerging technologies are highly popular devices and technologies that considerably improve our daily living by reducing or replacing human workforces, treating disease, monitoring healthcare, enhancing service performance, improving quality, and protecting the natural environment, and promoting non-gas emissions, sustainable working, green technologies, and renewable energy. Triboelectric nanogenerators (TENGs) have recently emerged as a type of advanced energy harvesting technology that is simple, green, renewable, flexible, and endurable as an energy resource. High-performance TENGs, denoted as advanced TENGs, have potential for use in many practical applications such as in self-powered sensors and sources, portable electric devices, power grid penetration, monitoring manufacturing processes for quality control, and in medical and healthcare applications that meet the criteria for smart devices and emerging technologies. Advanced TENGs are used as highly efficient energy harvesters that can convert many types of wasted mechanical energy into the electric energy used in a range of practical applications in our daily lives. This article reviews recently advanced TENGs and their potential for use with smart devices and emerging technology applications. The work encourages and strengthens motivation to develop new smart devices and emerging technologies to serve us in many fields of our daily living. When TENGs are introduced into smart devices and emerging technologies, they can be applied in a variety of practical applications such as the food processing industry, information and communication technology, agriculture, construction, transportation, marine technology, the energy sector, mechanical processing, manufacturing, self-powered sensors, Industry 4.0, drug safety, and robotics due to their sustainable and renewable energy, light weight, cost effectiveness, flexibility, and self-powered portable energy sources. Their advantages, disadvantages, and solutions are also discussed for further research. Full article

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11 pages, 2480 KB

Open AccessArticle

In Situ Raman Measurement of the Growth of SiCOH Thin Film Using Hexamethyl-Disiloxane (HMDSO) Mixture Source in Semiconductor Interconnection

by Hwa Rim Lee, Tae Min Choi and Sung Gyu Pyo

Micromachines 2025, 16(11), 1202; https://doi.org/10.3390/mi16111202 - 23 Oct 2025

Abstract

This research focuses on the real-time monitoring of SiCOH thin films grown by chemical vapor deposition (CVD) using Raman spectroscopy. To ensure the reliability of CVD-deposited materials in semiconductor processes, the study analyzes the growth and properties of thin films in situ. With [...] Read more.

This research focuses on the real-time monitoring of SiCOH thin films grown by chemical vapor deposition (CVD) using Raman spectroscopy. To ensure the reliability of CVD-deposited materials in semiconductor processes, the study analyzes the growth and properties of thin films in situ. With the increasing demand for low-dielectric constant (low-k) materials due to the miniaturization of semiconductor components, real-time monitoring becomes essential for controlling film thickness, quality, and composition during deposition. Dual laser wavelengths (405 nm and 532 nm) were used to capture Raman spectra and observe changes in film thickness, crystallinity, and the bonding structures of Si-C, Si-OH, and C-C. The results demonstrate that Raman spectroscopy effectively detects real-time molecular changes in thin films, showing a clear correlation between deposition time and film properties such as crystallinity and bond formation. This approach provides valuable insights for optimizing semiconductor thin film processes in real-time. Full article

(This article belongs to the Special Issue Thin Film Microelectronic Devices and Circuits, 2nd Edition)

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10 pages, 5463 KB

Open AccessArticle

High-Power Single-Frequency Continuous-Wave Tunable 1064/532 nm Dual-Wavelength Laser

by Weina Peng, Pixian Jin, Jing Su, Jiao Wei and Huadong Lu

Micromachines 2025, 16(11), 1201; https://doi.org/10.3390/mi16111201 - 23 Oct 2025

Abstract

A high-power single-frequency continuous-wave wideband continuously tunable dual-wavelength laser at 1064/532 nm is presented in this paper. Firstly, a thermally insensitive cavity containing a type-I phase-matching LiB₃O₅ crystal and an uncoated quartz etalon was specially designed, which provided the fundamental [...] Read more.

A high-power single-frequency continuous-wave wideband continuously tunable dual-wavelength laser at 1064/532 nm is presented in this paper. Firstly, a thermally insensitive cavity containing a type-I phase-matching LiB₃O₅ crystal and an uncoated quartz etalon was specially designed, which provided the fundamental condition for the generation of a high-power single-frequency 1064 nm and 532 nm laser. By carefully optimizing the mode matching, the maximal output powers of 13.3 W at 1064 nm and 12.5 W at 532 nm were achieved when the pump power was 63.7 W, and the total optical–optical efficiency of 40.5% was achieved. After the transmission peak of etalon was locked to the oscillating frequency of the resonator, the continuous frequency tuning ranges of the achieved laser were as wide as 26.75 GHz at 1064 nm and 53.5 GHz at 532 nm. Full article

(This article belongs to the Special Issue Advanced Optoelectronic Materials/Devices and Their Applications)

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27 pages, 3092 KB

Open AccessReview

The Multi-Conductivity Clausius–Mossotti Factor as an Electrophysiology Rosetta Stone: Dielectrophoresis, Membrane Potential and Zeta Potential

by Michael Pycraft Hughes

Micromachines 2025, 16(11), 1200; https://doi.org/10.3390/mi16111200 - 23 Oct 2025

Abstract

Dielectrophoresis (DEP) has been used for decades to estimate the passive electrical properties of cells. However, the body of work on cell electrophysiology derived from Clausius–Mossotti analysis of DEP-derived data pales to insignificance against the wider backdrop of cell electrophysiology based on the [...] Read more.

Dielectrophoresis (DEP) has been used for decades to estimate the passive electrical properties of cells. However, the body of work on cell electrophysiology derived from Clausius–Mossotti analysis of DEP-derived data pales to insignificance against the wider backdrop of cell electrophysiology based on the Goldman–Hodgkin–Katz equation measured by patch clamp, which focuses on membrane potential V_m—a parameter which does not appear in the Clausius–Mossotti model—and values of patch clamp-derived membrane conductance which, shorn of double-layer conductivity, are often orders of magnitude lower than those derived from DEP. Conversely, the body of work on DEP analysis is more substantial than that reporting the electrical properties of the extracellular (ζ) potential. To address this, several studies have recently been published into the interconnections between the electrical properties determined by the Clausius–Mossotti model, V_m, and ζ-potential, which analyzed the effect of varying the suspending medium conductivity over a wide range, from below 50 mSm⁻¹ to above 1.5 Sm⁻¹. The results of these studies identified relationships between the cytoplasm conductivity, V_m, membrane conductance and capacitance, surface conductance, whole-cell resistance, and ζ-potential. Significantly, many of these relationships only become apparent when analyzed as a function of the conductivity of the suspending medium. This paper assembles these interconnections, using several separate studies approaching different parameter connections, to draw together a set of equations which collectively form a “cellular electrome”. This demonstrates that analysis of the Clausius–Mossotti factor across multiple conductivities allows determination of not only passive electrical properties, but also the membrane and ζ-potential, and accurately predicts DEP behavior at higher conductivity for the first time. Full article

(This article belongs to the Special Issue Electrokinetic Principles in Biological and Biomedical Systems)

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14 pages, 3360 KB

Open AccessArticle

Localized Electric Field Tailoring to Balance Voltage Reliability, Current Density, and High-Frequency Performance of AlGaN/GaN HEMTs

by Yuxin Wang, Jiangwen Wang, Zilong Dong, Peiran Tian, Yuxiu Liu, Junyi Zhai and Weiguo Hu

Micromachines 2025, 16(11), 1199; https://doi.org/10.3390/mi16111199 - 22 Oct 2025

Abstract

Emerging applications including advanced industrial manufacturing, cutting-edge scientific research and medical equipment demand AlGaN/GaN HEMTs possessing both high-frequency and high-voltage characteristics. However, a persistent trade-off remains between the frequency characteristics and breakdown characteristics of these devices. In this study, we employed localized electric [...] Read more.

Emerging applications including advanced industrial manufacturing, cutting-edge scientific research and medical equipment demand AlGaN/GaN HEMTs possessing both high-frequency and high-voltage characteristics. However, a persistent trade-off remains between the frequency characteristics and breakdown characteristics of these devices. In this study, we employed localized electric field tailoring (LEFT) by introducing materials with different dielectric constants to construct a non-uniform composite gate dielectric layer, aiming to balance the breakdown voltage and cut-off frequency of the device. Device models were developed using APSYS-2018 software and their reliability was experimentally validated. Research data indicates that, compared to traditional uniform high-k (typically with dielectric constants k > 10, such as HfO₂ and HfZrO) gate dielectrics, the non-uniform composite gate dielectric structure demonstrates superior transconductance, saturation current density and cut-off frequency, with minimal degradation in breakdown voltage. Specifically, relative to HfO₂ and HfZrO uniform devices, the Al₂O₃/HfO₂ and Al₂O₃/HfZrO non-uniform HEMTs achieved 20.0% and 35.2% increases in cut-off frequency, respectively. Meanwhile, breakdown voltage remained above 97% of their uniform counterparts, saturation current density and transconductance increased by approximately 5%. Therefore, this non-uniform composite gate dielectric layer structure of AlGaN/GaN HEMT with LEFT holds great potential for industrial plasma generators, magnetic resonance imaging systems and biomedical radiofrequency hyperthermia devices. Full article

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

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19 pages, 2469 KB

Open AccessArticle

Tuning Multi-Wavelength Reflection Properties of Porous Silicon Bragg Reflectors Using Silver-Nanoparticle-Assisted Electrochemical Etching

by Sheng-Yang Huang, Hsiao-Han Hsu, Amal Muhammed Musthafa, I-An Lin, Chia-Man Chou and Vincent K. S. Hsiao

Micromachines 2025, 16(11), 1198; https://doi.org/10.3390/mi16111198 - 22 Oct 2025

Abstract

This study proposes an innovative silver-nanoparticle-assisted electrochemical etching method for the fabrication of porous silicon Bragg reflectors with multi-wavelength reflection characteristics. By introducing silver nanoparticles at varying concentrations (0.1–10 mg/mL) into the conventional HF–ethanol electrolyte and applying periodically modulated current densities (40/100 mA/cm [...] Read more.

This study proposes an innovative silver-nanoparticle-assisted electrochemical etching method for the fabrication of porous silicon Bragg reflectors with multi-wavelength reflection characteristics. By introducing silver nanoparticles at varying concentrations (0.1–10 mg/mL) into the conventional HF–ethanol electrolyte and applying periodically modulated current densities (40/100 mA/cm²), the transition from single-peak to multi-peak reflection spectra was successfully achieved. The results demonstrate that at a concentration of 10 mg/mL silver nanoparticles, up to four distinct reflection bands can be obtained. A systematic investigation was conducted on the influence of etching cycles (4–20 cycles) and silver nanoparticle concentration on the optical performance and microstructure. SEM analysis revealed well-defined periodic multilayer structures, while XPS analysis confirmed the presence of metallic silver on the porous silicon surface. This work provides a simple, controllable, and cost-effective approach to the development of multifunctional photonic devices, with promising applications in laser optics, solar cells, chemical sensing, and surface-enhanced Raman scattering. Full article

(This article belongs to the Special Issue Micro-Nano Photonics: From Design and Fabrication to Application)

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24 pages, 10398 KB

Open AccessArticle

An Enhanced Cooling Method for Power Modules on All-Electric Ships Based on Parameter Optimization and Special-Shaped Design of Sintered Heat Pipes

by Binyu Wang, Ting Lu, Qisheng Wu, Bobin Yao, Hongwei Zhang, Xiwei Zhou and Weiyu Liu

Micromachines 2025, 16(11), 1197; https://doi.org/10.3390/mi16111197 - 22 Oct 2025

Abstract

This paper proposes an enhanced cooling method for multi-chip power modules (e.g., in MMC inverters) with uneven power loss in all-electric propulsion ships based on sintered heat pipe parameter optimization and special-shaped design. First, five key parameters of straight sintered heat pipes were [...] Read more.

This paper proposes an enhanced cooling method for multi-chip power modules (e.g., in MMC inverters) with uneven power loss in all-electric propulsion ships based on sintered heat pipe parameter optimization and special-shaped design. First, five key parameters of straight sintered heat pipes were optimized: placement directly under hotspot chips, 10 mm in diameter, quantity matching the number of hotspot chips, length equal to the heatsink side length, and direction perpendicular to heatsink fins. Then, a C-shaped heat pipe was designed using the parallel thermal resistance principle, which forms two parallel low-thermal-resistance paths and outperforms conventional U-shaped ones. Finite element simulations showed that the hotspot temperature of the conventional heatsink was 91.26 °C, while it dropped to 87.35 °C with optimized straight heat pipes and further to 80.85 °C with C-shaped ones. Experiments verified an 11.65% temperature reduction (from 86.7 °C of conventional heatsinks to 76.6 °C of C-shaped heat pipe heatsinks). This method effectively lowers hotspot temperatures, reduces device failure rates, improves the thermal reliability of power modules, and provides a generalized design methodology for heatsinks of various power electronic converters. Full article

(This article belongs to the Special Issue Latest Advancements in Semiconductor Materials, Devices, and Systems, 2nd Edition)

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18 pages, 3331 KB

Open AccessArticle

Optical Vibration Sensing Bionic Vector Hydrophone Based on Mechanically Coupled Structure

by Jinying Zhang, Jianyu Peng, Xianmei Wu, Yifan Shi, Wenpeng Xu, Yiyao Wang, Rong Zhang, Ziqi Li and Bingwen An

Micromachines 2025, 16(11), 1196; https://doi.org/10.3390/mi16111196 - 22 Oct 2025

Abstract

Vector hydrophones play an extremely important role in marine exploration. How to reduce the size of vector hydrophones while improving their directional detection capability is a critical issue that needs to be addressed. The auditory organ of the fly Ormia ochracea represents a [...] Read more.

Vector hydrophones play an extremely important role in marine exploration. How to reduce the size of vector hydrophones while improving their directional detection capability is a critical issue that needs to be addressed. The auditory organ of the fly Ormia ochracea represents a prime example of achieving high-resolution directional detection within a compact size range. This paper proposes a vector hydrophone that integrates an Ormia ochracea fly-inspired mechanically coupled structure with an optical fiber vibration sensing structure, offering advantages of small size and strong electromagnetic interference immunity. The hydrophone demonstrates a good response to acoustic pulse trains and can accurately demodulate acoustic waves from 1 kHz to 10 kHz. Directional response experiments show that this hydrophone can significantly amplify the time delay differences of incoming acoustic waves. At an acoustic frequency of 9.25 kHz, the time delay amplification factor reaches approximately 50 times within the range of −90° to +90°, exhibiting good cosine directionality. Full article

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33 pages, 3868 KB

Open AccessReview

Application of Polymer Lubricants in Triboelectric Energy Harvesting: A Review

by Ali Nawaz and Hong-Joon Yoon

Micromachines 2025, 16(11), 1195; https://doi.org/10.3390/mi16111195 - 22 Oct 2025

Abstract

The range of lubricant applications has broadened to include multiple sectors, aiming to optimize the operational efficiency of mechanical systems. Given their adaptable friction-reducing properties, lubricants have recently been incorporated into energy harvesting technologies such as triboelectric nanogenerators (TENGs). In such devices, lubricants [...] Read more.

The range of lubricant applications has broadened to include multiple sectors, aiming to optimize the operational efficiency of mechanical systems. Given their adaptable friction-reducing properties, lubricants have recently been incorporated into energy harvesting technologies such as triboelectric nanogenerators (TENGs). In such devices, lubricants are essential for mitigating wear, facilitating heat dissipation, eliminating contaminants, and prolonging the service life of mechanically actuated energy harvesters. Notably, emerging developments in sliding and rotational-mode TENGs leverage lubricants to improve electrical output while reducing interface degradation. However, despite significant potential, TENGs still face inherent challenges, including interface friction and energy losses from air breakdown. Recent research indicates that these drawbacks can be effectively addressed by the intentional use of polymer-based lubricants, which contribute to maintaining micro/nanostructured surfaces and minimizing air breakdown, thereby enhancing charge storage capability and increasing device robustness. This review systematically examines the categories, physicochemical attributes, and operational roles of polymeric lubricants used in TENG technology. It underscores their combined function is both primary and support materials to augment triboelectric efficiency. In addition, the article assesses how different lubricants impact device performance and durability, providing a critical analysis of their suitability based on the operational benchmarks of lubricant-embedded TENG configurations. Full article

(This article belongs to the Special Issue Research Progress in Energy Harvesters and Self-Powered Sensors)

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11 pages, 2858 KB

Open AccessArticle

Optimization Design of High-Performance Powder-Spreading Arm for Metal 3D Printers

by Guoqing Zhang, Junxin Li, Xiaoyu Zhou, Yongsheng Zhou, Juanjuan Xie and Yuchao Bai

Micromachines 2025, 16(11), 1194; https://doi.org/10.3390/mi16111194 - 22 Oct 2025

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Abstract

The powder-laying arm of a metal 3D printer is heavy, which can easily cause long-term damage to the powder-laying servomotor or belt, so it is necessary to design a lightweight powder-laying arm. To this end, we first use 3D modeling Rhino software to [...] Read more.

The powder-laying arm of a metal 3D printer is heavy, which can easily cause long-term damage to the powder-laying servomotor or belt, so it is necessary to design a lightweight powder-laying arm. To this end, we first use 3D modeling Rhino software to rebuild the powder-laying arm, and then, we carry out topology optimization design on the rebuilt powder-laying arm in Altair Inspire software. Finally, we use the Aurora Elva 3D printer to complete manufacturing and assembly to verify compatibility. The results show that the maximum displacement of the original powder-spreading arm is concentrated in the lower right corner at 4.319 × 10⁻⁵ mm; the maximum stress is concentrated in the middle transition part, decreasing toward the ends; the maximum stress is 3.843 × 10⁻² MPa; the stress concentration and deformation of the powder-spreading arm when spreading powder is small, which provides a large optimization space. The topology-optimized powder-spreading arm, with a 25% quality objective, maintains the integrity of the connection with the fixing hole while having a large mass reduction. The surface of the parts of the completed 3D-printed powder arm is bright, with low roughness, and there is no obvious warping and deformation or other defects; the completed 3D-printed powder-spreading arm and the assembly of the wall are closely coordinated with each other, and the location of the screw holes is appropriate, having no obvious assembly conflicts between the parts, which lays the foundation for the mass production of the powder-spreading arm of high-performance metal 3D printers. Full article

(This article belongs to the Special Issue 3D/4D Printing of Multifunctional Composites with Multifunctional Applications)

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11 pages, 2907 KB

Open AccessArticle

Electrical Characterization and Simulation of GaN-on-Si Pseudo-Vertical MOSFETs with Frequency-Dependent Gate C–V Investigation

by Valentin Ackermann, Mohammed El Amrani, Blend Mohamad, Riadh Ben Abbes, Matthew Charles, Sebastien Cavalaglio, Manuel Manrique, Julien Buckley and Bassem Salem

Micromachines 2025, 16(11), 1193; https://doi.org/10.3390/mi16111193 - 22 Oct 2025

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Abstract

This work presents a comprehensive study of GaN-on-Si pseudo-vertical MOSFETs focusing on single-trench and multi-trench designs. Thanks to a gate-first process flow based on an Al₂O₃/TiN MOS stack, both fabricated devices exhibit promising transistor behavior, with steady normally OFF [...] Read more.

This work presents a comprehensive study of GaN-on-Si pseudo-vertical MOSFETs focusing on single-trench and multi-trench designs. Thanks to a gate-first process flow based on an Al₂O₃/TiN MOS stack, both fabricated devices exhibit promising transistor behavior, with steady normally OFF operation, very low gate leakage current, and good switching performance. Following the extraction of a low effective channel mobility, the frequency dependence of gate-to-source C–V characteristics is studied. In addition, using TCAD Sentaurus Synopsys simulations, the impact of positive fixed charge and donor-type defects at the p-GaN/dielectric interface is investigated, together with the frequency dependency. Finally, by comparing experimental and simulated results, a mechanism is proposed linking the observed threshold voltage shift to the presence of sharp trench-bottom micro-trenching. This mechanism may further explain the origin of the additional C–V hump observed at high frequencies, which could arise from charge trapping at the p-GaN/dielectric interface or from charge inversion in the p-GaN region. Full article

(This article belongs to the Special Issue GaN-Based Materials and Devices: Research and Applications, 2nd Edition)

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21 pages, 1373 KB

Open AccessReview

Applicability Analysis of High-Voltage Transmission and Substation Equipment Based on Silicon Carbide Devices

by Huiyuan Zhang, Ming Nie, Qinxiao Dong, He Liu, Pengfei Jia, Zhiyuan Li and Yonghao Fang

Micromachines 2025, 16(11), 1192; https://doi.org/10.3390/mi16111192 - 22 Oct 2025

Abstract

Power electronics is an important feature of the new power system. The high-speed development of the new power system has gradually increased the requirements for high-efficiency and high-reliability high-voltage transmission and substation equipment. Silicon carbide (SiC) devices, which have the advantages of fast [...] Read more.

Power electronics is an important feature of the new power system. The high-speed development of the new power system has gradually increased the requirements for high-efficiency and high-reliability high-voltage transmission and substation equipment. Silicon carbide (SiC) devices, which have the advantages of fast switching speed, low power loss, and high-temperature resistance, are the key core technology for the upgrading of high-voltage transmission and substation equipment. The paper begins by examining the evolution of the demand for high efficiency, compact and reliable power electronic devices for high-voltage transmission and substation systems at different stages of energy development. SiC has emerged as a key technological path to break through the physical limits of silicon-based devices, due to its outstanding material properties. Silicon-based devices encounter significant bottlenecks in high-voltage and high-frequency applications, with high switching losses and a junction temperature tolerance that is typically limited to 150 °C. In contrast, SiC devices can reduce switching losses by 60–80% and operate stably at temperatures up to 200 °C or even higher, thereby significantly enhancing system efficiency and power density. Finally, the paper provides a systematic analysis of the application of SiC devices in high-voltage transmission and substation equipment, exploring and identifying the technical bottlenecks and future research directions for SiC-based high-voltage transmission equipment. Full article

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15 pages, 3114 KB

Open AccessArticle

Impact of Extrinsic Defects in Wavelength Separation Coatings on the Process of Laser-Induced Damage

by Shichen Shen, Xinda Zhou, Yinbo Zheng, Jie Li, Tianhao Zhang, Linjie Zhao, Liqun Chai and Mingjun Chen

Micromachines 2025, 16(11), 1191; https://doi.org/10.3390/mi16111191 - 22 Oct 2025

Viewed by 60

Abstract

Wavelength separation coatings can effectively separate the fundamental frequency (1ω) and third harmonic (3ω) laser beams. However, the laser-induced damage threshold (LIDT) of the surface defect-free WS coatings for the 3ω laser is 1.68 J/cm² (obtained in the preliminary experiment), significantly lower [...] Read more.

Wavelength separation coatings can effectively separate the fundamental frequency (1ω) and third harmonic (3ω) laser beams. However, the laser-induced damage threshold (LIDT) of the surface defect-free WS coatings for the 3ω laser is 1.68 J/cm² (obtained in the preliminary experiment), significantly lower than the ideal LIDT of the fused silica substrate (80 J/cm²). This is directly correlated with extrinsic defects such as nanoscale defects and nodular defects introduced during the coating manufacturing process. Moreover, the damage in WS coatings caused by extrinsic defects is a complex physical process involving multiple physical phenomena such as material melting, vaporization, and ejection. The mechanism by which extrinsic defects interact with lasers to form damage is not yet fully elucidated. To address this, a multi-physics coupling model considering photoelectric, thermal and stress was established to simulate the incident laser propagation within coatings, the temperature distribution and thermal stress distribution of the coating material. This model systematically investigates the influence of defect location, type, and size on the laser-induced damage process. It is found that when a 10 nm-diameter defect is located at the 32nd layer of the coatings, the light intensity enhancement factor (LIEF) for 3ω laser can reach up to 5 times that for the 1ω laser. The variation in thermal stress induced by changes in defect size is jointly determined by the defect-induced modulation effect and the interference effect realized by the coating. This work theoretically reveals the mechanism of extrinsic defects in the laser damage. It provides effective guidance for establishing control standards for extrinsic defects during the optical coating process. Full article

(This article belongs to the Special Issue Advances in Digital Manufacturing and Nano Fabrication)

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Micromachines, Volume 16, Issue 11 (November 2025) – 22 articles

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