Micromachines

11 pages, 5770 KiB

Open AccessArticle

Dual-Polarized Metasurface-Integrated Antenna for Integrated Imaging of LWIR Camera and SAR

by Jijian Hu, Zhenghong Dong, Lurui Xia and Xueqi Chen

Micromachines 2025, 16(2), 202; https://doi.org/10.3390/mi16020202 - 10 Feb 2025

The integrated imaging of LWIR cameras and SAR is one of the important directions of multi-sensor integration. In order to reduce the structural complexity of LWIR cameras and SAR-integrated imaging antenna, a dual-polarized metasurface-integrated antenna (MIA) is designed in this paper. It is [...] Read more.

The integrated imaging of LWIR cameras and SAR is one of the important directions of multi-sensor integration. In order to reduce the structural complexity of LWIR cameras and SAR-integrated imaging antenna, a dual-polarized metasurface-integrated antenna (MIA) is designed in this paper. It is composed of a microwave metasurface antenna and an optical metalens, and the metalens is embedded in the center of the metasurface antenna. The MIA uses the powerful electromagnetic wave control ability to simplify the optical and microwave signal transmission paths and reduce the number of devices. At the same time, in order to expand the function of the MIA, based on the principle of metasurface, the dual-linearly polarized and dual-circularly polarized MIAs are designed and simulated, respectively. The results show that the designed dual-polarized MIA has good performance. This paper provides a new scheme for the integrated imaging system of LWIR cameras and SAR with simple structure, diverse functions and easy integration. Full article

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34 pages, 5213 KiB

Open AccessReview

Organ-on-a-Chip Applications in Microfluidic Platforms

by Ling An, Yi Liu and Yaling Liu

Micromachines 2025, 16(2), 201; https://doi.org/10.3390/mi16020201 - 10 Feb 2025

Abstract

Microfluidic technology plays a crucial role in organ-on-a-chip (OoC) systems by replicating human physiological processes and disease states, significantly advancing biomedical research and drug discovery. This article reviews the design and fabrication processes of microfluidic devices. It also explores how these technologies are [...] Read more.

Microfluidic technology plays a crucial role in organ-on-a-chip (OoC) systems by replicating human physiological processes and disease states, significantly advancing biomedical research and drug discovery. This article reviews the design and fabrication processes of microfluidic devices. It also explores how these technologies are integrated into OoC platforms to simulate human physiological environments, highlighting key principles, technological advances, and diverse applications. Through case studies involving the simulation of multiple organs such as the heart, liver, and lungs, the article evaluates the impact of OoC systems’ integrated microfluidic technology on drug screening, toxicity assessment, and personalized medicine. In addition, this article considers technical challenges, ethical issues, and future directions, and looks ahead to further optimizing the functionality and biomimetic precision of OoCs through innovation, emphasizing its critical role in promoting personalized medicine and precision treatment strategies. Full article

(This article belongs to the Special Issue Microfluidics for Single Cell Detection and Cell Sorting)

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14 pages, 5684 KiB

Open AccessArticle

High-Precision Small-Signal Model for Double-Channel–High-Electron-Mobility Transistors Based on the Double-Channel Coupling Effect

by Ziyue Zhao, Qian Yu, Yang Lu, Chupeng Yi, Xin Liu, Ting Feng, Wei Zhao, Yilin Chen, Ling Yang, Xiaohua Ma and Yue Hao

Micromachines 2025, 16(2), 200; https://doi.org/10.3390/mi16020200 - 10 Feb 2025

Abstract

This paper presents a new small-signal model for double-channel (DC)–high-electron-mobility transistors, developed through an analysis of the unique coupling effects between channels in devices. Unlike conventional single-channel HEMTs, where electrons only transport laterally in the channel, DC-HEMTs exhibit additional vertical transport between the [...] Read more.

This paper presents a new small-signal model for double-channel (DC)–high-electron-mobility transistors, developed through an analysis of the unique coupling effects between channels in devices. Unlike conventional single-channel HEMTs, where electrons only transport laterally in the channel, DC-HEMTs exhibit additional vertical transport between the two channels along the material direction. This double-channel coupling effect significantly limits the applicability of traditional small-signal models to DC-HEMTs. Firstly, the coupling effect between the two channels is characterized by introducing the double-channel coupling sub-model, which consists of R_GaN, R_AlN, and C_AlN. At the same time, by introducing parameters gm_{_upper} and gm_{_lower}, the new model can accurately characterize the properties of double channels. Secondly, initial values for R_GaN, R_AlN, and C_AlN are calculated based on the device’s physical structure and material properties. Similarly, initial values for gm_{_upper} and gm_{_lower} are derived from the device’s DC measurement and TCAD simulation results. Furthermore, a comprehensive parameter extraction method enables the optimized extraction of intrinsic parameters, completing the model’s construction. Finally, validation of the model’s fitting reveals a significantly reduced error compared to traditional small-signal models. This enhanced accuracy not only verifies the precise representation of the device’s physical characteristics but also demonstrates the model’s effectiveness. Full article

(This article belongs to the Special Issue Wide-Bandgap Semiconductor Devices: Materials, Fabrication, and Applications)

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11 pages, 11809 KiB

Open AccessArticle

A Fast Slicing Method for Colored Models Based on Colored Triangular Prism and OpenGL

by Lei Xia and Ran Yan

Micromachines 2025, 16(2), 199; https://doi.org/10.3390/mi16020199 - 9 Feb 2025

Abstract

Colored 3D printing, as one of the crucial directions in 3D printing technology, has been widely applied in various fields in recent years. Compared to traditional 3D printing, colored 3D printing introduces color information to achieve multi-material identification of different regions in the [...] Read more.

Colored 3D printing, as one of the crucial directions in 3D printing technology, has been widely applied in various fields in recent years. Compared to traditional 3D printing, colored 3D printing introduces color information to achieve multi-material identification of different regions in the model structure, enabling the fabrication of heterogeneous and complex components. This presents unique advantages in both visual effects and functionality, making it of significant value in fields such as metal manufacturing, bioengineering, and artistic design. However, during the construction of colored models, technical challenges such as low-slicing contour accuracy and poor color reproduction persist. Existing slicing methods for colored models are often accompanied by contour offset, deformation, color distortion, and low rendering efficiency, severely limiting the application scope of colored 3D printing technology. To address these challenges, this paper proposes a “Fast Slicing Method for Colored Models Based on Colored Triangular Prisms and OpenGL”. This method first constructs colored triangular prisms to effectively solve the problems of color contour offset and deformation, achieving uniform thickness offset of the colors. Then, by utilizing OpenGL rendering technology, the method overcomes color abruptness, simplifies bitmap rendering processes, and ensures smooth color transitions while significantly improving rendering efficiency. In summary, the proposed slicing method can effectively enhance the accuracy of slicing contours and color reproduction, significantly expanding the application range of colored 3D printing. Full article

18 pages, 5900 KiB

Open AccessArticle

Research on Deflection and Stress Analyses and the Improvement of the Removal Uniformity of Silicon in a Single-Sided Polishing Machine Under Pressure

by Guoqing Ye and Zhenqiang Yao

Micromachines 2025, 16(2), 198; https://doi.org/10.3390/mi16020198 - 8 Feb 2025

Abstract

The chemical–mechanical polishing (CMP) of silicon wafers involves high-precision surface machining after double-sided lapping. Silicon wafers are subjected to chemical corrosion and mechanical removal under pressurized conditions. The multichip CMP process for 4~6-inch silicon wafers, such as those in MOSFETs (Metal Oxide Semiconductor [...] Read more.

The chemical–mechanical polishing (CMP) of silicon wafers involves high-precision surface machining after double-sided lapping. Silicon wafers are subjected to chemical corrosion and mechanical removal under pressurized conditions. The multichip CMP process for 4~6-inch silicon wafers, such as those in MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated-Gate Bipolar Transistors), and MEMS (Micro-Electromechanical System) field materials, is conducted to maintain multiple chips to improve efficiency and improve polish removal uniformity; that is, the detected TTV (total thickness variation) gradually increases from 10 μm to less than 3 μm. In this work, first, a mathematical model for calculating the small deflection of silicon wafers under pressure is established, and the limit values under two boundary conditions of fixed support and simple support are calculated. Moreover, the removal uniformity of the silicon wafers is improved by improving the uniformity of the wax-coated adhesion state and adjusting the boundary conditions to reflect a fixed support state. Then, the stress distribution of the silicon wafers under pressure is simulated, and the calculation methods for measuring the TTV of the silicon wafers and the uniformity measurement index are described. Stress distribution is changed by changing the size of the pressure ring to achieve the purpose of removing uniformity. This study provides a reference for improving the removal uniformity of multichip silicon wafer chemical–mechanical polishing. Full article

(This article belongs to the Special Issue Functional Materials and Microdevices, 2nd Edition)

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3 pages, 136 KiB

Open AccessEditorial

Research Progress on Insulated Gate Bipolar Transistor (IGBT) Modules

by Peisheng Liu and Yaohui Deng

Micromachines 2025, 16(2), 197; https://doi.org/10.3390/mi16020197 - 8 Feb 2025

Abstract

With the rapid advancement of social productivity and technological innovation, the insulated gate bipolar transistor (IGBT) has emerged as a cornerstone in modern power electronic devices [...] Full article

(This article belongs to the Special Issue Insulated Gate Bipolar Transistor (IGBT) Modules)

14 pages, 37756 KiB

Open AccessArticle

Optimized Phase-Generated Carrier Demodulation Algorithm for Membrane-Free Fabry-Pérot Acoustic Sensor with High Sensitivity

by Yang Yang, Xinyu Zhao, Yongqiu Zheng, Juan Cui, Dongqing Zhao, Zhixuan Zheng, Yan Cao and Chenyang Xue

Micromachines 2025, 16(2), 196; https://doi.org/10.3390/mi16020196 - 8 Feb 2025

Abstract

Demodulation of fiber optic Fabry–Pérot (F-P) acoustic sensors with high sensitivity and a large dynamic range continues to pose significant challenges. In this paper, we propose an advanced phase-generated carrier (PGC) demodulation algorithm, applied innovatively to membrane-free F-P acoustic sensors operating under high [...] Read more.

Demodulation of fiber optic Fabry–Pérot (F-P) acoustic sensors with high sensitivity and a large dynamic range continues to pose significant challenges. In this paper, we propose an advanced phase-generated carrier (PGC) demodulation algorithm, applied innovatively to membrane-free F-P acoustic sensors operating under high sound pressure. The algorithm optimizes acoustic demodulation results by adjusting the mixing phase delay, achieving the best signal to noise and distortion ratio (SINAD) and total harmonic distortion (THD) (<1%). Additionally, by introducing the cosine component of the acoustic signal obtained directly after filtering the interference signal, into the demodulation algorithm process, the sensitivity of the sensor at high sound pressure is significantly improved. The experimental results show that the ameliorated algorithm obtains a demodulation sensitivity of

34.95 μ

rad/Pa and a THD of 0.87%, both of which are superior to traditional PGC demodulation algorithms under the same experimental conditions. At the same time, the minimum detectable sound pressure of

129.73 {mPa/Hz}^{1 / 2}

was obtained, and the sound pressure tested in the experiment at a frequency of 1 kHz was as high as 3169.78 Pa (164 dB). With the proposed algorithm, the flatness of the frequency response is ±0.82 dB from 100 Hz to 33 kHz, and a dynamic range of up to 102.6 dB was obtained, making it relevant in the field of aerospace acoustic measurements. Full article

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Graphical abstract

18 pages, 4880 KiB

Open AccessArticle

Design, Analysis, and Simulation of a MEMS Tuning Fork Gyroscope with a Mechanical Amplification Structure

by Haotian Hu, Benedetta Calusi, Alvise Bagolini and Maria F. Pantano

Micromachines 2025, 16(2), 195; https://doi.org/10.3390/mi16020195 - 8 Feb 2025

Abstract

This paper describes a novel micro-electro-mechanical system (MEMS) tuning fork gyroscope (TFG) design that employs a chevron-shaped displacement mechanism to amplify the displacement generated by the Coriolis force, thereby increasing the TFG’s mechanical sensitivity. This approach was evaluated using both theoretical modeling and [...] Read more.

This paper describes a novel micro-electro-mechanical system (MEMS) tuning fork gyroscope (TFG) design that employs a chevron-shaped displacement mechanism to amplify the displacement generated by the Coriolis force, thereby increasing the TFG’s mechanical sensitivity. This approach was evaluated using both theoretical modeling and finite element analysis (FEA), and the results showed a high degree of agreement between the two methods. A conventional TFG having a comparable area was also designed and analyzed for comparison purposes. By introducing the displacement amplification mechanism, the proposed MEMS TFG design provides an output displacement about 2.5 times higher than the conventional design, according to the computation, without increasing the device footprint. Theoretical analysis and FEA on the TFG with amplification and a conventional TFG confirmed that the amplified displacement significantly improves the mechanical sensitivity of the gyroscope compared to conventional TFG designs. Full article

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76 pages, 5996 KiB

Open AccessReview

From Present Innovations to Future Potential: The Promising Journey of Lithium-Ion Batteries

by Pooya Parvizi, Milad Jalilian, Alireza Mohammadi Amidi, Mohammad Reza Zangeneh and Jordi-Roger Riba

Micromachines 2025, 16(2), 194; https://doi.org/10.3390/mi16020194 - 7 Feb 2025

Abstract

Lithium-ion batteries (LIBs) have become integral to modern technology, powering portable electronics, electric vehicles, and renewable energy storage systems. This document explores the complexities and advancements in LIB technology, highlighting the fundamental components such as anodes, cathodes, electrolytes, and separators. It delves into [...] Read more.

Lithium-ion batteries (LIBs) have become integral to modern technology, powering portable electronics, electric vehicles, and renewable energy storage systems. This document explores the complexities and advancements in LIB technology, highlighting the fundamental components such as anodes, cathodes, electrolytes, and separators. It delves into the critical interplay of these components in determining battery performance, including energy density, cycling stability, and safety. Moreover, the document addresses the significant sustainability challenges posed by the widespread adoption of LIBs, focusing on resource depletion and environmental impact. Various recycling practices, including hydrometallurgy, pyrometallurgy, and direct recycling, are evaluated for their efficiency in metal recovery and ecological footprint. The advancements in recycling technologies aim to mitigate the adverse effects of LIB waste, emphasizing the need for sustainable and scalable solutions. The research underscores the importance of ongoing innovation in electrode materials and recycling methodologies, reminding us of our responsibility and commitment to finding and implementing these solutions, as this continuous improvement is crucial to enhance the performance, safety, and sustainability of LIBs, ensuring their continued relevance in the evolving energy storage landscape. Full article

(This article belongs to the Special Issue Nanotechnology in Li-Ion Batteries and Beyond)

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13 pages, 2045 KiB

Open AccessArticle

A Hardware Accelerator for Real-Time Processing Platforms Used in Synthetic Aperture Radar Target Detection Tasks

by Yue Zhang, Yunshan Tang, Yue Cao and Zhongjun Yu

Micromachines 2025, 16(2), 193; https://doi.org/10.3390/mi16020193 - 7 Feb 2025

Abstract

The deep learning object detection algorithm has been widely applied in the field of synthetic aperture radar (SAR). By utilizing deep convolutional neural networks (CNNs) and other techniques, these algorithms can effectively identify and locate targets in SAR images, thereby improving the accuracy [...] Read more.

The deep learning object detection algorithm has been widely applied in the field of synthetic aperture radar (SAR). By utilizing deep convolutional neural networks (CNNs) and other techniques, these algorithms can effectively identify and locate targets in SAR images, thereby improving the accuracy and efficiency of detection. In recent years, achieving real-time monitoring of regions has become a pressing need, leading to the direct completion of real-time SAR image target detection on airborne or satellite-borne real-time processing platforms. However, current GPU-based real-time processing platforms struggle to meet the power consumption requirements of airborne or satellite applications. To address this issue, a low-power, low-latency deep learning SAR object detection algorithm accelerator was designed in this study to enable real-time target detection on airborne and satellite SAR platforms. This accelerator proposes a Process Engine (PE) suitable for multidimensional convolution parallel computing, making full use of Field-Programmable Gate Array (FPGA) computing resources to reduce convolution computing time. Furthermore, a unique memory arrangement design based on this PE aims to enhance memory read/write efficiency while applying dataflow patterns suitable for FPGA computing to the accelerator to reduce computation latency. Our experimental results demonstrate that deploying the SAR object detection algorithm based on Yolov5s on this accelerator design, mounted on a Virtex 7 690t chip, consumes only 7 watts of dynamic power, achieving the capability to detect 52.19 512 × 512-sized SAR images per second. Full article

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

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13 pages, 1878 KiB

Open AccessArticle

Integrated Device for Cancer Nucleic Acid Biomarker Detection at Body Temperature

by Chang Chen, Bin Wu, Xuesong Li, Yuhang Jin, Hangyu Zhang, Bo Liu, Zhengyao Zhang and Na Li

Micromachines 2025, 16(2), 192; https://doi.org/10.3390/mi16020192 - 7 Feb 2025

Abstract

The quantitative analysis of nucleic acid markers is extensively utilized in cancer detection. However, it faces significant challenges, such as the need for specialized detection devices and the inherent complexity of testing procedures. To address these issues, this study proposes a simplified, rapid, [...] Read more.

The quantitative analysis of nucleic acid markers is extensively utilized in cancer detection. However, it faces significant challenges, such as the need for specialized detection devices and the inherent complexity of testing procedures. To address these issues, this study proposes a simplified, rapid, and user-friendly platform for cancer nucleic acid marker detection. We firstly designed a polydimethylsiloxane (PDMS) device for the isothermal amplification reaction of nucleic acid biomarkers based on reverse-transcription recombinase-aided amplification (RT-RAA) technology. Specifically, three potential cancer nucleic acid biomarkers, carcinoembryonic antigen (CEA), prostate-specific antigen (PSA), and prostate cancer antigen 3 (PCA3) were amplified from human serum or urine samples in the PDMS device at body temperature. The reaction chamber was directly integrated with nucleic acid test strips labeled with colloidal gold nanoparticles, allowing for the visual observation of the detection results for the amplification products. The optimal reaction conditions, such as pH, reaction time, antibody, and streptavidin concentration, were defined after a series of optimization studies. The findings demonstrated that the optimal RT-RAA reaction time was 20 min, the primary antibodies were labeled with colloidal gold to the greatest extent at pH 8.5, and the optimal concentrations of secondary antibody and streptavidin were 1.0 mg/mL and 0.5 mg/mL, respectively. Furthermore, this novel detection approach could not only exhibit excellent sensitivity and specificity but also show high accuracy for the analysis of nucleic acid biomarkers in both clinical serum and urine samples. Therefore, the simplified and more convenient operation platform provides a new insight for the semi-quantitative analysis of cancer nucleic acid biomarkers and the rapid screening of early cancer, thereby offering a promising alternative to oncological point-of-care testing (POCT) diagnostics. Full article

23 pages, 10686 KiB

Open AccessArticle

Impact of Layer Materials, Their Thicknesses, and Their Reflectivities on Emission Color and NVIS Compatibility in OLED Devices for Avionic Display Applications

by Esin Uçar, Alper Ülkü, Halil Mert Kaya, Ramis Berkay Serin, Rifat Kaçar, Ahmet Yavuz Oral and Ebru Menşur

Micromachines 2025, 16(2), 191; https://doi.org/10.3390/mi16020191 - 7 Feb 2025

Abstract

Organic Light Emitting Diode (OLED) technology is preferred in modern display applications due to its superior efficiency, color quality, and flexibility. It also carries a high potential of applicability in military displays where emission color tuning is required for MIL-STD-3009 Night Vision Imaging [...] Read more.

Organic Light Emitting Diode (OLED) technology is preferred in modern display applications due to its superior efficiency, color quality, and flexibility. It also carries a high potential of applicability in military displays where emission color tuning is required for MIL-STD-3009 Night Vision Imaging Systems (NVISs), as compatibility is critical. Herein, we report the effects of different OLED device layer materials and thicknesses such as the hole injection layer (HIL), hole transport layer (HTL), and electron transport layer (ETL) on the color coordinates, luminance, and efficiency of OLED devices designed for night vision (NVIS) compatibility. In this study, simulation tools like SETFOS^® (Semi-conducting Emissive Thin Film Optics Simulator), MATLAB^®, and LightTools^® (Illumination Design Software) were used to verify and validate the luminance, luminance efficiency, and chromaticity coordinates of the proposed NVIS-OLED devices. We modeled the OLED device using SETFOS^®, then the selection of materials for each layer for an optimal electron–hole balance was performed in the same tool. The effective reflectivity of multiple OLED layers was determined in MATLAB^® in addition to an optimal device efficiency calculation in SETFOS^®. The optical validation of output luminance and luminous efficiency was performed in LightTools^®. Through a series of simulations for a green-emitting OLED device, we observed significant shifts in color coordinates, particularly towards the yellow spectrum, when the ETL materials and their thicknesses varied between 1 nm and 200 nm, whereas a change in the thickness of the HIL and HTL materials had a negligible impact on the color coordinates. While the critical role of ETL in color tuning and the emission characteristics of OLEDs is highlighted, our results also suggested a degree of flexibility in material selection for the HIL and HTL, as they minimally affected the color coordinates of emission. We validated via a combination of SETFOS^®, MATLAB^®, and LightTools^® that when the ETL (3TPYMB) material thickness is optimized to 51 nm, the cathode reflectivity via the ETL-EIL stack became the minimum enabling output luminance of 3470 cd/m2 through our emissive layer within the Glass/ITO/MoO₃/TAPC/(CBP:Ir(ppy)₃)/3TPYMB/LiF/Aluminum OLED stack architecture, also yielding 34.73 cd/A of current efficiency under 10 mA/cm² of current density. We infer that when stack layer thicknesses are optimized with respect to their reflectivity properties, better performances are achieved. Full article

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20 pages, 5569 KiB

Open AccessReview

Design and Fabrication of Microelectrodes for Dielectrophoresis and Electroosmosis in Microsystems for Bio-Applications

by Mengren Wu, Zijian Liu and Yuan Gao

Micromachines 2025, 16(2), 190; https://doi.org/10.3390/mi16020190 - 7 Feb 2025

Abstract

Microfluidic technology has emerged as a multidisciplinary field, integrating fluid dynamics, electronics, materials science, etc., enabling precise manipulation of small volumes of fluids and particles for various bio-applications. Among the forms of energy integrated into microfluidic systems, electric fields are particularly advantageous for [...] Read more.

Microfluidic technology has emerged as a multidisciplinary field, integrating fluid dynamics, electronics, materials science, etc., enabling precise manipulation of small volumes of fluids and particles for various bio-applications. Among the forms of energy integrated into microfluidic systems, electric fields are particularly advantageous for achieving precise control at the microscale. This review focuses on the design and fabrication of microelectrodes that drive electrokinetic phenomena, dielectrophoresis (DEP) and electroosmotic flow (EOF), key techniques for particle and fluid manipulation in microfluidic devices. DEP relies on non-uniform electric fields to manipulate particles based on their dielectric properties, while EOF utilizes uniform electric fields to generate consistent fluid flow across microchannels. Advances in microelectrode fabrication, including photolithography, soft lithography, and emerging non-cleanroom techniques, are discussed. Additionally, the review explores innovative approaches such as rapid prototyping, contactless electrodes, and three-dimensional structures, along with material considerations like conductive polymers and carbon composites. The review discusses the role of microelectrodes in enhancing device functionality, scalability, and reliability. The paper also identifies challenges, including the need for improved fabrication reproducibility and multifunctional integration. Finally, potential future research directions are proposed to further optimize DEP- and EOF-based microsystems for advanced biomedical and diagnostic applications. Full article

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7 pages, 713 KiB

Open AccessEditorial

Editorial for the Special Issue on MEMS/NEMS Devices and Applications, 2nd Edition

by Yao-Chuan Tsai, Pin-Chun Huang and Ching-Liang Dai

Micromachines 2025, 16(2), 189; https://doi.org/10.3390/mi16020189 - 7 Feb 2025

Abstract

Microelectromechanical systems (MEMSs) and nanoelectromechanical systems (NEMSs) are revolutionary technologies that merge mechanical and electronic components on microscopic and nanoscopic scales [...] Full article

(This article belongs to the Special Issue MEMS/NEMS Devices and Applications, 2nd Edition)

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15 pages, 6026 KiB

Open AccessArticle

A 3.3 kV SiC Semi-Superjunction MOSFET with Trench Sidewall Implantations

by Marco Boccarossa, Kyrylo Melnyk, Arne Benjamin Renz, Peter Michael Gammon, Viren Kotagama, Vishal Ajit Shah, Luca Maresca, Andrea Irace and Marina Antoniou

Micromachines 2025, 16(2), 188; https://doi.org/10.3390/mi16020188 - 6 Feb 2025

Abstract

Superjunction (SJ) technology offers a promising solution to the challenges faced by silicon carbide (SiC) Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs) operating at high voltages (>3 kV). However, the fabrication of SJ devices presents significant challenges due to fabrication complexity. This paper presents [...] Read more.

Superjunction (SJ) technology offers a promising solution to the challenges faced by silicon carbide (SiC) Metal Oxide Semiconductor Field-Effect Transistors (MOSFETs) operating at high voltages (>3 kV). However, the fabrication of SJ devices presents significant challenges due to fabrication complexity. This paper presents a comprehensive analysis of a feasible and easy-to-fabricate semi-superjunction (SSJ) design for 3.3 kV SiC MOSFETs. The proposed approach utilizes trench etching and sidewall implantation, with a tilted trench to facilitate the implantation process. Through Technology Computer-Aided Design (TCAD) simulations, we investigate the effects of the p-type sidewall on the charge balance and how it affects key performance characteristics, such as breakdown voltage (BV) and on-state resistance (R_DS-ON). In particular, both planar gate (PSSJ) and trench gate (TSSJ) designs are simulated to evaluate their performance improvements over conventional planar MOSFETs. The PSSJ design achieves a 2.5% increase in BV and a 48.7% reduction in R_DS-ON, while the TSSJ design further optimizes these trade-offs, with a 3.1% improvement in BV and a significant 64.8% reduction in R_DS-ON compared to the benchmark. These results underscore the potential of tilted trench SSJ designs to significantly enhance the performance of SiC SSJ MOSFETs for high-voltage power electronics while simplifying fabrication and lowering costs. Full article

(This article belongs to the Special Issue SiC Based Miniaturized Devices, 3rd Edition)

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19 pages, 2366 KiB

Open AccessReview

Electro-Elastic Instability and Turbulence in Electro-osmotic Flows of Viscoelastic Fluids: Current Status and Future Directions

by Chandi Sasmal

Micromachines 2025, 16(2), 187; https://doi.org/10.3390/mi16020187 - 4 Feb 2025

Abstract

The addition of even minute amounts of solid polymers, measured in parts per million (ppm), into a simple Newtonian fluid like water significantly alters the flow behavior of the resulting polymer solutions due to the introduction of fluid viscoelasticity. This viscoelastic behavior, which [...] Read more.

The addition of even minute amounts of solid polymers, measured in parts per million (ppm), into a simple Newtonian fluid like water significantly alters the flow behavior of the resulting polymer solutions due to the introduction of fluid viscoelasticity. This viscoelastic behavior, which arises due to the stretching and relaxation phenomena of polymer molecules, leads to complex flow dynamics that are starkly different from those seen in simple Newtonian fluids under the same conditions. In addition to polymer solutions, many other fluids, routinely used in various industries and our daily lives, exhibit viscoelastic properties, including emulsions; foams; suspensions; biological fluids such as blood, saliva, and cerebrospinal fluid; and suspensions of biomolecules like DNA and proteins. In various microfluidic platforms, these viscoelastic fluids are often transported using electro-osmotic flows (EOFs), where an electric field is applied to control fluid movement. This method provides more precise and accurate flow control compared to pressure-driven techniques. However, several experimental and numerical studies have shown that when either the applied electric field strength or the fluid elasticity exceeds a critical threshold, the flow in these viscoelastic fluids becomes unstable and asymmetric due to the development of electro-elastic instability (EEI). These instabilities are driven by the normal elastic stresses in viscoelastic fluids and are not observed in Newtonian fluids under the same conditions, where the flow remains steady and symmetric. As the electric field strength or fluid elasticity is further increased, these instabilities can transition into a more chaotic and turbulent-like flow state, referred to as electro-elastic turbulence (EET). This article comprehensively reviews the existing literature on these EEI and EET phenomena, summarizing key findings from both experimental and numerical studies. Additionally, this article presents a detailed discussion of future research directions, emphasizing the need for further investigations to fully understand and harness the potential of EEI and EET in various practical applications, particularly in microscale flow systems where better flow control and increased transport rates are essential. Full article

(This article belongs to the Collection Micro/Nanoscale Electrokinetics)

16 pages, 2258 KiB

Open AccessArticle

Design and Fabrication of a Piezoelectric Bimorph Microphone with High Reliability and Dynamic Range Based on Al_0.8Sc_0.2N

by Ruixiang Yan, Yucheng Ji, Anyuan Liu, Lei Wang and Songsong Zhang

Micromachines 2025, 16(2), 186; https://doi.org/10.3390/mi16020186 - 4 Feb 2025

Abstract

With the development of technology, MEMS microphones, which are small-sized and highly uniform, have been applied extensively. To improve their reliability in extreme environment and overcome the constraints of traditional microphones, this article presents a piezoelectric bimorph MEMS microphone using [...] Read more.

With the development of technology, MEMS microphones, which are small-sized and highly uniform, have been applied extensively. To improve their reliability in extreme environment and overcome the constraints of traditional microphones, this article presents a piezoelectric bimorph MEMS microphone using

{Al}_{0.8} {Sc}_{0.2} N

. In the article, the high robustness of piezoelectric microphones and the reasons for choosing

{Al}_{0.8} {Sc}_{0.2} N

as piezoelectric materials are described. The sensitivity of an

{Al}_{0.8} {Sc}_{0.2} N

-based piezoelectric bimorph compared with the traditional structure are revealed through FEA. Subsequently, a lumped element microphone model is constructed and all noise sources are evaluated comprehensively. The difference in output noise caused by different structures is calculated. The designed piezoelectric microphone, which comprises eight triangular cantilever beams, was fabricated on a chip with an area of 900

μ

m × 900

μ

m. The sensitivity of the designed microphone achieves 1.68 mV/Pa, with a noise floor of −110 dBA and SNR of 54.5 dB. The acoustic overload point of the microphone stands at 147 dB SPL, and following the impact test, the survival rate was 100%. Compared to traditional MEMS microphones, the microphone achieves a dynamic range of 107.5 dB. Full article

(This article belongs to the Section A：Physics)

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16 pages, 3723 KiB

Open AccessArticle

Real-Time 0.89 THz Terahertz Imaging with High-Electron-Mobility Transistor Detector and Hydrogen Cyanide Laser for Non-Destructive Nut Detection

by Nu Zhang, Haiqing Liu, Huihui Yan, Hongbei Wang, Jiaxing Xie, Yinxian Jie and Damao Yao

Micromachines 2025, 16(2), 185; https://doi.org/10.3390/mi16020185 - 4 Feb 2025

Abstract

We present a method for real-time terahertz imaging that employs a hydrogen cyanide (HCN) laser as a terahertz source at 0.89 THz and an AlGaN/GaN high-electron-mobility transistor (HEMT) terahertz detector as a camera. We developed an HCN laser and constructed a transmission imaging [...] Read more.

We present a method for real-time terahertz imaging that employs a hydrogen cyanide (HCN) laser as a terahertz source at 0.89 THz and an AlGaN/GaN high-electron-mobility transistor (HEMT) terahertz detector as a camera. We developed an HCN laser and constructed a transmission imaging system based on it. This combination utilizes a high-power HCN laser with a highly sensitive terahertz detector, enabling practical applications of real-time terahertz imaging. A resolution test plane was produced to determine that the system could achieve a lateral resolution of 2 mm, and real-time terahertz imaging was carried out on Siemens star, pistachios, and sunflower seeds. The results demonstrate that the hidden structures inside nuts can be observed by terahertz imaging. Through our analysis of terahertz images of both sunflower seeds and pine nuts, we successfully assessed their fullness and demonstrated the capability to distinguish between full and unfilled nuts. These findings validate the potential of this technique for future applications in nut detection. We discuss the limitations of the current setup, potential improvements, and possible applications, and we outline the introduction of aspherical lenses and terahertz transmission tomography. Full article

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

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11 pages, 13085 KiB

Open AccessArticle

Mechanism of OH*-Modified 4H-SiC Surface with Scratches Based on ReaxFF MD Simulation

by Dongxiao Yan, Hui Huang, Mingpu Xue and Nian Duan

Micromachines 2025, 16(2), 184; https://doi.org/10.3390/mi16020184 - 3 Feb 2025

Abstract

OH* generated through plasma catalysis offers several advantages, including a long survival time, high modification efficiency, and environmental friendliness. Consequently, a plasma-assisted polishing technology has rapidly developed. Previous studies exploring the interaction mechanism between OH* and 4H-SiC have often assumed flat surfaces. However, [...] Read more.

OH* generated through plasma catalysis offers several advantages, including a long survival time, high modification efficiency, and environmental friendliness. Consequently, a plasma-assisted polishing technology has rapidly developed. Previous studies exploring the interaction mechanism between OH* and 4H-SiC have often assumed flat surfaces. However, in the surface modification experiments on 4H-SiC, the actual surface morphology was not flat but contained numerous scratches. Therefore, this study investigated the interaction mechanism of OH* on an uneven surface using reactive force field molecular dynamics (ReaxFF MD) simulations. The results show that in the low-speed OH* modification process, the adsorption effect leads to a thicker modified layer at higher locations than at lower locations. The resulting modified layer can be removed by soft abrasive mechanical polishing to achieve surface flatness, but there will be a modified layer on the surface, which needs to be modified and polished several times. In contrast, during high-speed OH* modification, high-speed particle bombardment causes more Si-O bonds to diffuse into the scratches, resulting in the formation of a flat bonding layer with surface planarization achieved after a single polishing step. The interaction mechanism of OH* with the uneven surface at different speeds, as obtained through ReaxFF MD, provides a theoretical foundation for subsequent polishing experiments. Full article

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

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