Journal Description
Micromachines
Micromachines
is a peer-reviewed, open access journal on the science and technology of small structures, devices and systems, published monthly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), PubMed, PMC, Ei Compendex, dblp, and other databases.
- Journal Rank: JCR - Q2 (Chemistry, Analytical) / CiteScore - Q2 (Mechanical Engineering)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 16.1 days after submission; acceptance to publication is undertaken in 1.9 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Testimonials: See what our editors and authors say about Micromachines.
Impact Factor:
3.4 (2022);
5-Year Impact Factor:
3.3 (2022)
Latest Articles
Fly-Cutting Processing of Micro-Triangular Pyramid Arrays and Synchronous Micro-Scrap Removal
Micromachines 2024, 15(5), 655; https://doi.org/10.3390/mi15050655 - 16 May 2024
Abstract
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Many micro-scraps are generated when a micro-triangular pyramid array (MTPA) is machined by the fly-cutting method. Micro-scraps are generally not removed quickly enough; therefore, these residual micro-scraps participate in the cutting process again, scratching the workpiece surface and accelerating diamond tool wear. To
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Many micro-scraps are generated when a micro-triangular pyramid array (MTPA) is machined by the fly-cutting method. Micro-scraps are generally not removed quickly enough; therefore, these residual micro-scraps participate in the cutting process again, scratching the workpiece surface and accelerating diamond tool wear. To remove micro-scraps rapidly, a fly-cutting method to produce MTPAs on vertically oriented working surfaces was developed during this study. The results show that an MTPA produced by fly cutting on a vertical workpiece had a clearly outlined structure, high dimensional accuracy, and a low surface roughness. There was no micro-scrap residue on the workpiece surface and the diamond tool wear was small. The cutting inlet edges had no burrs, and the cutting outlet edges had only a small number of burrs. This method of fly cutting MTPAs on vertically oriented working surfaces provides a foundation for the development of high-precision micro-triangular pyramid optical elements.
Full article
Open AccessArticle
Research on the Influence of the Material Removal Profile of a Spherical Polishing Tool on the Mid-Spatial Frequency Errors of Optical Surfaces
by
Zhaohao He, Kuo Hai, Kailong Li, Jiahao Yu, Lingwei Wu, Lin Zhang, Xing Su, Lisheng Cai, Wen Huang and Wei Hang
Micromachines 2024, 15(5), 654; https://doi.org/10.3390/mi15050654 - 15 May 2024
Abstract
Elastic spherical polishing tools effectively conform to the polishing surface and exhibit high efficiency in the removal of materials, so they are extensively used in the sub-aperture polishing stages of optical components. However, their processing is often accompanied by significant mid-spatial frequency (MSF)
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Elastic spherical polishing tools effectively conform to the polishing surface and exhibit high efficiency in the removal of materials, so they are extensively used in the sub-aperture polishing stages of optical components. However, their processing is often accompanied by significant mid-spatial frequency (MSF) errors, which critically degrade the performance of optical systems. To suppress the MSF errors generated during polishing with spherical tools, this study investigates the influence factor of MSF errors during the polishing process through an analysis of the convolution effect in material removal. A material removal profile model is established, and a uniform removal simulation is conducted to assess the influence of different shape material removal profiles on MSF errors. Simulation and experimental results show that a Gaussian-like shape material removal profile is more effective in suppressing the MSF errors during polishing compared to the “W” and trapezoidal shape material removal profiles. In addition, based on the characteristics of the RMS decreasing in a serrated trend with the decrease in path spacing, a path spacing optimization method considering the polishing efficiency is proposed to improve the polishing efficiency while controlling the MSF errors, and the effectiveness of the path spacing optimization method is verified by comparing the MSF error at the maximum theoretical path spacing and the path spacing that is less than this. Finally, the path spacing optimization method is used to polish single-crystal silicon to further illustrate its practicality.
Full article
(This article belongs to the Special Issue Precision Optical Manufacturing and Processing)
Open AccessArticle
Rapid and Sensitive Detection by Combining Electric Field Effects and Surface Plasmon Resonance: A Theoretical Study
by
Qijie Qiu and Yan Xu
Micromachines 2024, 15(5), 653; https://doi.org/10.3390/mi15050653 - 15 May 2024
Abstract
Surface plasmon resonance (SPR) has been extensively employed in biological sensing, environmental detection, as well as chemical industry. Nevertheless, the performance possessed by conventional surface plasmon resonance (SPR) biosensors can be further limited by the transport of analyte molecules to the sensing surface,
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Surface plasmon resonance (SPR) has been extensively employed in biological sensing, environmental detection, as well as chemical industry. Nevertheless, the performance possessed by conventional surface plasmon resonance (SPR) biosensors can be further limited by the transport of analyte molecules to the sensing surface, noteworthily when small molecules or low levels of substances are being detected. In this study, a rapid and highly sensitive SPR biosensor is introduced to enhance the ability of the target analytes’ collection by integrating AC electroosmosis (ACEO) and dielectrophoresis (DEP). Both the above-mentioned phenomena principally arise from the generation of the AC electric fields. This generation can be tailored by shaping the interdigitated electrodes (IDEs) that also serve as the SPR biomarker sensing area. The effects exerted by different parameters (e.g., the frequency and voltage of the AC electric field as well as microelectrode structures) are considered in the iSPR (interdigitated SPR) biosensor operation, and the iSPR biosensors are optimized with the sensitivity. The results of this study confirm that the iSPR can efficiently concentrate small molecules into the SPR sensing area, such that SPR reactions achieve an order of magnitude increase, and the detection time is shortened. The rapid and sensitive sensor takes on critical significance in the development of on-site diagnostics in a wide variety of human and animal health applications.
Full article
(This article belongs to the Special Issue Micromachines for Dielectrophoresis, 3rd Edition)
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Open AccessArticle
Synthesis of Submicron CaCO3 Particles in 3D-Printed Microfluidic Chips Supporting Advection and Diffusion Mixing
by
Ivan Reznik, Ekaterina Kolesova, Anna Pestereva, Konstantin Baranov, Yury Osin, Kirill Bogdanov, Jacobus Swart, Stanislav Moshkalev and Anna Orlova
Micromachines 2024, 15(5), 652; https://doi.org/10.3390/mi15050652 - 15 May 2024
Abstract
Microfluidic technology provides a solution to the challenge of continuous CaCO3 particle synthesis. In this study, we utilized a 3D-printed microfluidic chip to synthesize CaCO3 micro- and nanoparticles in vaterite form. Our primary focus was on investigating a continuous one-phase synthesis
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Microfluidic technology provides a solution to the challenge of continuous CaCO3 particle synthesis. In this study, we utilized a 3D-printed microfluidic chip to synthesize CaCO3 micro- and nanoparticles in vaterite form. Our primary focus was on investigating a continuous one-phase synthesis method tailored for the crystallization of these particles. By employing a combination of confocal and scanning electron microscopy, along with Raman spectroscopy, we were able to thoroughly evaluate the synthesis efficiency. This evaluation included aspects such as particle size distribution, morphology, and polymorph composition. The results unveiled the existence of two distinct synthesis regimes within the 3D-printed microfluidic chips, which featured a channel cross-section of 2 mm2. In the first regime, which was characterized by chaotic advection, particles with an average diameter of around 2 m were produced, thereby displaying a broad size distribution. Conversely, the second regime, marked by diffusion mixing, led to the synthesis of submicron particles (approximately 800–900 nm in diameter) and even nanosized particles (70–80 nm). This research significantly contributes valuable insights to both the understanding and optimization of microfluidic synthesis processes, particularly in achieving the controlled production of submicron and nanoscale particles.
Full article
(This article belongs to the Special Issue Microfluidics and 3D Printing for Biomedical Applications)
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Open AccessArticle
Development of Wearable Textile MIMO Antenna for Sub-6 GHz Band New Radio 5G Applications
by
Pendli Pradeep, Mohammed Mahaboob Basha, Srinivasulu Gundala and Javed Syed
Micromachines 2024, 15(5), 651; https://doi.org/10.3390/mi15050651 - 15 May 2024
Abstract
In this paper, an irregular octagonal two-port MIMO patch antenna is designed specifically for New Radio (NR) 5G applications in the mid-band sub-6 GHz. The proposed antenna comprises an irregularly shaped patch antenna equipped with a regular 50-ohm feed line and a parasitic
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In this paper, an irregular octagonal two-port MIMO patch antenna is designed specifically for New Radio (NR) 5G applications in the mid-band sub-6 GHz. The proposed antenna comprises an irregularly shaped patch antenna equipped with a regular 50-ohm feed line and a parasitic strip line antenna, and is partially grounded. Jeans material serves as a substrate with an effective dielectric constant of 1.6 and a thickness of 1 mm. This material is studied experimentally. The proposed antenna design undergoes analysis and optimization using the ANSYS HFSS tool. Furthermore, the design incorporates the influence of the slot on both the ground plane and the parasitic strip line to optimize performance, enhance isolation, and improve impedance matching among antenna elements. The dimensions of the jeans substrate are 40 mm × 50 mm. The simulated impedance bandwidth ranged from 3.6 GHz to 7 GHz and the measured bandwidth was slightly narrower, from 4.35 GHz to 7 GHz. The simulation results demonstrated an isolation level greater than 12 dB between antenna elements, while the measured results reached 28.5 dB, and the peak gain for this proposed antenna stood at 6.74 dB. These qualities made this proposed antenna suitable for various New Radio mid-band 5G wireless applications within the sub-6 GHz band, such as N79, Wi-Fi-5/6, V2X, and DSRC applications.
Full article
(This article belongs to the Special Issue Recent Advances in Microwave Components and Devices, 2nd Edition)
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Open AccessArticle
Carbon Nanotube-Based Printed All-Organic Microelectrode Arrays for Neural Stimulation and Recording
by
Tatsuya Murakami, Naoki Yada and Shotaro Yoshida
Micromachines 2024, 15(5), 650; https://doi.org/10.3390/mi15050650 - 14 May 2024
Abstract
In this paper, we report a low-cost printing process of carbon nanotube (CNT)-based, all-organic microelectrode arrays (MEAs) suitable for in vitro neural stimulation and recording. Conventional MEAs have been mainly composed of expensive metals and manufactured through high-cost and complex lithographic processes, which
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In this paper, we report a low-cost printing process of carbon nanotube (CNT)-based, all-organic microelectrode arrays (MEAs) suitable for in vitro neural stimulation and recording. Conventional MEAs have been mainly composed of expensive metals and manufactured through high-cost and complex lithographic processes, which have limited their accessibility for neuroscience experiments and their application in various studies. Here, we demonstrate a printing-based fabrication method for microelectrodes using organic CNT/paraffin ink, coupled with the deposition of an insulating layer featuring single-cell-sized sensing apertures. The simple microfabrication processes utilizing the economic and readily available ink offer potential for cost reduction and improved accessibility of MEAs. Biocompatibility of the fabricated microelectrode was suggested through a live/dead assay of cultured neural cells, and its large electric double layer capacitance was revealed by cyclic voltammetry that was crucial for preventing cytotoxic electrolysis during electric neural stimulation. Furthermore, the electrode exhibited sufficiently low electric impedance of 2.49 Ω·cm2 for high signal-to-noise ratio neural recording, and successfully captured model electric waves in physiological saline solution. These results suggest the easily producible and low-cost printed all-organic microelectrodes are available for neural stimulation and recording, and we believe that they can expand the application of MEA in various neuroscience research.
Full article
(This article belongs to the Special Issue Selected Papers from the 14th Symposium on Micro-Nano Science and Technology on Micromachines)
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Open AccessArticle
Broadening Bandwidth in a Semi-Active Vibration Absorption System Utilizing Stacked Polyvinyl Chloride Gel Actuators
by
Zhuoyuan Li, Chen Liu, Meiping Sheng, Minqing Wang, Hualing Chen, Bo Li and Peng Xia
Micromachines 2024, 15(5), 649; https://doi.org/10.3390/mi15050649 - 14 May 2024
Abstract
Plasticized polyvinyl chloride (PVC) gel is a new soft and smart material, whose potential in electroactive variable stiffness can be used for vibration control in soft robotic systems. In this paper, a new semi-active vibration absorber is developed by stacking PVC gel actuator
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Plasticized polyvinyl chloride (PVC) gel is a new soft and smart material, whose potential in electroactive variable stiffness can be used for vibration control in soft robotic systems. In this paper, a new semi-active vibration absorber is developed by stacking PVC gel actuator units. The absorption bandwidth of a single PVC gel absorber covers the range of three natural frequencies (76.5 Hz, 95 Hz, 124 Hz) of a rectangular steel plate in vibration attenuation. The maximum reduction percentage in acceleration amplitude is 63%. With stacked PVC gel actuator units, the absorption bandwidth can be shifted and obviously broadened.
Full article
(This article belongs to the Special Issue Soft Actuators: Design, Fabrication and Applications)
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Open AccessArticle
Modeling and Reliability Analysis of MEMS Gyroscope Rotor Parameters under Vibrational Stress
by
Lei Wang, Yuehong Pan, Kai Li, Lilong He, Qingyi Wang and Weidong Wang
Micromachines 2024, 15(5), 648; https://doi.org/10.3390/mi15050648 - 14 May 2024
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Vibrational environments can cause drift or changes in Micro-Electro-Mechanical System (MEMS) gyroscope rotor parameters, potentially impacting their performance. To improve the effective use of MEMS gyroscopes, this study introduced a method for evaluating the reliability of parameter degradation under vibration. We analyzed the
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Vibrational environments can cause drift or changes in Micro-Electro-Mechanical System (MEMS) gyroscope rotor parameters, potentially impacting their performance. To improve the effective use of MEMS gyroscopes, this study introduced a method for evaluating the reliability of parameter degradation under vibration. We analyzed the working principle of MEMS gyroscope rotors and investigated how vibration affects their parameters. Focusing on zero bias and scale factor as key performance indicators, we developed an accelerated degradation model using the distributional assumption method. We then collected degradation data for these parameters under various vibration conditions. Using the Copula function, we established a reliability assessment approach to evaluate the degradation of the MEMS gyroscope rotor’s zero bias and scale factor under vibration, enabling the determination of reliability for these parameters. Experimental findings confirmed that increasing stress levels lead to reduced failure times and increased failure rates for MEMS gyroscope rotors, with significant changes observed in the zero bias parameter. Our evaluation method effectively characterizes changes in the reliability of the MEMS gyroscope rotor’s scale factor and zero bias over time, providing valuable information for practical applications of MEMS gyroscopes.
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Open AccessArticle
Integrative BNN-LHS Surrogate Modeling and Thermo-Mechanical-EM Analysis for Enhanced Characterization of High-Frequency Low-Pass Filters in COMSOL
by
Jorge Davalos-Guzman, Jose L. Chavez-Hurtado and Zabdiel Brito-Brito
Micromachines 2024, 15(5), 647; https://doi.org/10.3390/mi15050647 - 13 May 2024
Abstract
This paper pioneers a novel approach in electromagnetic (EM) system analysis by synergistically combining Bayesian Neural Networks (BNNs) informed by Latin Hypercube Sampling (LHS) with advanced thermal–mechanical surrogate modeling within COMSOL simulations for high-frequency low-pass filter modeling. Our methodology transcends traditional EM characterization
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This paper pioneers a novel approach in electromagnetic (EM) system analysis by synergistically combining Bayesian Neural Networks (BNNs) informed by Latin Hypercube Sampling (LHS) with advanced thermal–mechanical surrogate modeling within COMSOL simulations for high-frequency low-pass filter modeling. Our methodology transcends traditional EM characterization by integrating physical dimension variability, thermal effects, mechanical deformation, and real-world operational conditions, thereby achieving a significant leap in predictive modeling fidelity. Through rigorous evaluation using Mean Squared Error (MSE), Maximum Learning Error (MLE), and Maximum Test Error (MTE) metrics, as well as comprehensive validation on unseen data, the model’s robustness and generalization capability is demonstrated. This research challenges conventional methods, offering a nuanced understanding of multiphysical phenomena to enhance reliability and resilience in electronic component design and optimization. The integration of thermal variables alongside dimensional parameters marks a novel paradigm in filter performance analysis, significantly improving simulation accuracy. Our findings not only contribute to the body of knowledge in EM diagnostics and complex-environment analysis but also pave the way for future investigations into the fusion of machine learning with computational physics, promising transformative impacts across various applications, from telecommunications to medical devices.
Full article
(This article belongs to the Special Issue Selected Papers from the 20th SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference (IMOC 2023))
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Open AccessArticle
Evaluation of Phototoxicity of Short-Wavelength Laser Light Utilizing PCNA Accumulation
by
Tetsuya Matsuyama, Noboru Osaka, Mikiya Yamaguchi, Naohiro Kanamaru, Kenji Wada, Ai Kawakita, Kaori Murata, Kenji Sugimoto and Koichi Okamoto
Micromachines 2024, 15(5), 646; https://doi.org/10.3390/mi15050646 - 13 May 2024
Abstract
In recent years, diseases such as age-related macular degeneration and retinal pigment degeneration caused by excessive exposure to short-wavelength visible light have become significant concerns. With the aim of quantitatively evaluating the toxicity of short-wavelength light, proliferating cell nuclear antigen (PCNA) accumulation at
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In recent years, diseases such as age-related macular degeneration and retinal pigment degeneration caused by excessive exposure to short-wavelength visible light have become significant concerns. With the aim of quantitatively evaluating the toxicity of short-wavelength light, proliferating cell nuclear antigen (PCNA) accumulation at the irradiation site was investigated using live cell imaging techniques to irradiate individual living cells with short-wavelength laser light. By examining the dependency of PCNA accumulation on the irradiation site within the cells and their cell cycle, it was observed that PCNA accumulation occurred only when the cell nucleus of cells in the S phase of the cell cycle was irradiated. We investigated the accumulation of PCNA at the laser irradiation site using laser light at wavelengths of 405 nm and 375 nm, with intensities ranging from 0.5 μW to 9.0 μW. The results confirmed an increase in PCNA accumulation with increasing intensity, and a higher accumulation was observed with laser light irradiation at a wavelength of 375 nm compared to 405 nm. By comparing the PCNA accumulation and 24 h cell viability, we demonstrated the feasibility of quantitatively assessing laser light toxicity through the measurement of PCNA accumulation.
Full article
(This article belongs to the Special Issue Ultraviolet Devices and Ultraviolet Germicidal Irradiation)
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Open AccessArticle
Miniaturized and High Volumetric Energy Density Power Supply Device Based on a Broad-Frequency Vibration Driven Triboelectric Nanogenerator
by
Liting Wu, Zewei Ren, Yanjun Wang, Yumin Tang, Zhong Lin Wang and Rusen Yang
Micromachines 2024, 15(5), 645; https://doi.org/10.3390/mi15050645 - 13 May 2024
Abstract
The widespread vibration is one of the most promising energy sources for IoT and small sensors, and broad-frequency vibration energy harvesting is important. Triboelectric nanogenerators (TENGs) can convert vibration energy into electrical energy through triboelectricity and electrostatic induction, providing an effective solution to
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The widespread vibration is one of the most promising energy sources for IoT and small sensors, and broad-frequency vibration energy harvesting is important. Triboelectric nanogenerators (TENGs) can convert vibration energy into electrical energy through triboelectricity and electrostatic induction, providing an effective solution to the collection of broad-frequency vibration energy. Also, the power supply in constrained and compact spaces has been a long-standing challenge. Here, a miniaturized power supply (MPS) based on a broad-frequency vibration-driven triboelectric nanogenerator (TENG) is developed. The size of the MPS is 38 mm × 26 mm × 20 mm, which can adapt to most space-limited environments. The TENG device is optimized through theoretical mechanical modeling for the external stimuli, it can efficiently harvest vibrational energy in the frequency range of 1–100 Hz and has a high output power density of 134.11 W/cm3. The developed device demonstrates its practical application potential in powering small electronics like LEDs, watches, and timers.
Full article
(This article belongs to the Special Issue Emerging Applications of Triboelectric Effects/Materials)
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Open AccessCommunication
A High-Energy, Wide-Spectrum, Spatiotemporal Mode-Locked Fiber Laser
by
Boyuan Ge, Yajun Lou, Silin Guo, Yue Cai and Xinhai Zhang
Micromachines 2024, 15(5), 644; https://doi.org/10.3390/mi15050644 - 12 May 2024
Abstract
In this article, we demonstrate a high-energy, wide-spectrum, spatiotemporal mode-locked (STML) fiber laser. Unlike traditional single-mode fiber lasers, STML fiber lasers theoretically enable mode-locking with various combinations of transverse modes. The laser can deliver two different STML pulse sequences with different pulse widths,
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In this article, we demonstrate a high-energy, wide-spectrum, spatiotemporal mode-locked (STML) fiber laser. Unlike traditional single-mode fiber lasers, STML fiber lasers theoretically enable mode-locking with various combinations of transverse modes. The laser can deliver two different STML pulse sequences with different pulse widths, spectra and beam profiles, due to the different compositions of transverse modes in the output pulses. Moreover, we achieve a wide-spectrum pulsed output with a single-pulse energy of up to 116 nJ, by weakening the spectral filtering and utilizing self-cleaning. Strong spatial and spectral filtering are usually thought to be necessary for achieving STML. Our experiment verifies the necessity of spatial filtering for achieving STML, and we show that weakening unnecessary spectral filtering provides an effective way to increase the pulse energy and spectrum width of mode-locked fiber lasers.
Full article
(This article belongs to the Special Issue Fiber Lasers and Applications)
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Open AccessEditorial
Editorial for the Special Issue on Advanced Interconnect and Packaging, 2nd Edition
by
Dawei Wang and Wensheng Zhao
Micromachines 2024, 15(5), 643; https://doi.org/10.3390/mi15050643 - 11 May 2024
Abstract
Interconnect and packaging technologies are crucial aspects of modern electronics, and they are essential to achieve high performance, miniaturization and low power consumption of electronic equipment [...]
Full article
(This article belongs to the Special Issue Advanced Interconnect and Packaging, 2nd Edition)
Open AccessArticle
Research on Single-Event Burnout Reinforcement Structure of SiC MOSFET
by
Qiulan Liao and Hongxia Liu
Micromachines 2024, 15(5), 642; https://doi.org/10.3390/mi15050642 - 10 May 2024
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In this paper, the single-event burnout (SEB) and reinforcement structure of 1200 V SiC MOSFET (SG-SBD-MOSFET) with split gate and Schottky barrier diode (SBD) embedded were studied. The device structure was established using Sentaurus TCAD, and the transient current changes of single-event effect
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In this paper, the single-event burnout (SEB) and reinforcement structure of 1200 V SiC MOSFET (SG-SBD-MOSFET) with split gate and Schottky barrier diode (SBD) embedded were studied. The device structure was established using Sentaurus TCAD, and the transient current changes of single-event effect (SEE), SEB threshold voltage, as well as the regularity of electric field peak distribution transfer were studied when heavy ions were incident from different regions of the device. Based on SEE analysis of the new structural device, two reinforcement structure designs for SEB resistance were studied, namely the expansion of the P+ body contact area and the design of a multi-layer N-type interval buffer layer. Firstly, two reinforcement schemes for SEB were analyzed separately, and then comprehensive design and analysis were carried out. The results showed that the SEB threshold voltage of heavy ions incident from the N+ source region was increased by 16% when using the P+ body contact area extension alone; when the device is reinforced with a multi-layer N-type interval buffer layer alone, the SEB threshold voltage increases by 29%; the comprehensive use of the P+ body contact area expansion and a multi-layer N-type interval buffer layer reinforcement increased the SEB threshold voltage by 33%. Overall, the breakdown voltage of the reinforced device decreased from 1632.935 V to 1403.135 V, which can be seen as reducing the remaining redundant voltage to 17%. The device’s performance was not significantly affected.
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Open AccessArticle
Design and Analysis of 5-DOF Compact Electromagnetic Levitation Actuator for Lens Control of Laser Cutting Machine
by
Chuan Zhao, Qinwei Zhang, Wenzhe Pei, Junjie Jin, Feng Sun, Hongkui Zhang, Ran Zhou, Dongning Liu, Fangchao Xu, Xiaoyou Zhang and Lijian Yang
Micromachines 2024, 15(5), 641; https://doi.org/10.3390/mi15050641 - 10 May 2024
Abstract
In laser beam processing, the angle or offset between the auxiliary gas and the laser beam axis have been proved to be two new process optimization parameters for improving cutting speed and quality. However, a traditional electromechanical actuator cannot achieve high-speed and high-precision
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In laser beam processing, the angle or offset between the auxiliary gas and the laser beam axis have been proved to be two new process optimization parameters for improving cutting speed and quality. However, a traditional electromechanical actuator cannot achieve high-speed and high-precision motion control with a compact structure. This paper proposes a magnetic levitation actuator which could realize the 5-DOF motion control of a lens using six groups of differential electromagnets. At first, the nonlinear characteristic of a magnetic driving force was analyzed by establishing an analytical model and finite element calculation. Then, the dynamic model of the magnetic levitation actuator was established using the Taylor series. And the mathematical relationship between the detected distance and five-degree-of-freedom was determined. Next, the centralized control system based on PID control was designed. Finally, a driving test was carried out to verify the five-degrees-of-freedom motion of the proposed electromagnetic levitation actuator. The results show it can achieve a stable levitation and precision positioning with a desired command motion. It also proves that the proposed magnetic levitation actuator has the potential application in an off-axis laser cutting machine tool.
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(This article belongs to the Special Issue Recent Advances in Electromagnetic Devices)
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Open AccessReview
LDH-Based Voltammetric Sensors
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Domenica Tonelli, Matteo Tonelli, Stefano Gianvittorio and Andreas Lesch
Micromachines 2024, 15(5), 640; https://doi.org/10.3390/mi15050640 - 10 May 2024
Abstract
Layered double hydroxides (LDHs), also named hydrotalcite-like compounds, are anionic clays with a lamellar structure which have been extensively used in the last two decades as electrode modifiers for the design of electrochemical sensors. These materials can be classified into LDHs containing or
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Layered double hydroxides (LDHs), also named hydrotalcite-like compounds, are anionic clays with a lamellar structure which have been extensively used in the last two decades as electrode modifiers for the design of electrochemical sensors. These materials can be classified into LDHs containing or not containing redox-active centers. In the former case, a transition metal cation undergoing a reversible redox reaction within a proper potential window is present in the layers, and, therefore, it can act as electron transfer mediator, and electrocatalyze the oxidation of an analyte for which the required overpotential is too high. In the latter case, a negatively charged species acting as a redox mediator can be introduced into the interlayer spaces after exchanging the anion coming from the synthesis, and, again, the material can display electrocatalytic properties. Alternatively, due to the large specific surface area of LDHs, molecules with electroactivity can be adsorbed on their surface. In this review, the most significant electroanalytical applications of LDHs as electrode modifiers for the development of voltammetric sensors are presented, grouping them based on the two types of materials.
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(This article belongs to the Special Issue Advances in Voltammetric Sensors)
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Open AccessReview
A Review of Femtosecond Laser Processing of Silicon Carbide
by
Quanjing Wang, Ru Zhang, Qingkui Chen and Ran Duan
Micromachines 2024, 15(5), 639; https://doi.org/10.3390/mi15050639 - 10 May 2024
Abstract
Silicon carbide (SiC) is a promising semiconductor material as well as a challenging material to machine, owing to its unique characteristics including high hardness, superior thermal conductivity, and chemical inertness. The ultrafast nature of femtosecond lasers enables precise and controlled material removal and
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Silicon carbide (SiC) is a promising semiconductor material as well as a challenging material to machine, owing to its unique characteristics including high hardness, superior thermal conductivity, and chemical inertness. The ultrafast nature of femtosecond lasers enables precise and controlled material removal and modification, making them ideal for SiC processing. In this review, we aim to provide an overview of the process properties, progress, and applications by discussing the various methodologies involved in femtosecond laser processing of SiC. These methodologies encompass direct processing, composite processing, modification of the processing environment, beam shaping, etc. In addition, we have explored the myriad applications that arise from applying femtosecond laser processing to SiC. Furthermore, we highlight recent advancements, challenges, and future prospects in the field. This review provides as an important direction for exploring the progress of femtosecond laser micro/nano processing, in order to discuss the diversity of processes used for manufacturing SiC devices.
Full article
(This article belongs to the Special Issue Recent Advances in Micro/Nano-Fabrication)
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Open AccessArticle
An Electronically Reconfigurable Highly Selective Stop-Band Ultra-Wideband Antenna Applying Electromagnetic Bandgaps and Positive-Intrinsic-Negative Diodes
by
Anees Abbas, Niamat Hussain, Md. Abu Sufian, Wahaj Abbas Awan, Jaemin Lee and Nam Kim
Micromachines 2024, 15(5), 638; https://doi.org/10.3390/mi15050638 - 9 May 2024
Abstract
In this article, an ultra-wideband (UWB) antenna featuring two reconfigurable quasi-perfect stop bands at WLAN (5.25–5.75 GHz) and lower 5G (3.4–3.8 GHz) utilizing electromagnetic bandgaps (EBGs) and positive-intrinsic-negative (P-I-N) diodes is proposed. A pair of EBG structures are applied to generate sharp notch
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In this article, an ultra-wideband (UWB) antenna featuring two reconfigurable quasi-perfect stop bands at WLAN (5.25–5.75 GHz) and lower 5G (3.4–3.8 GHz) utilizing electromagnetic bandgaps (EBGs) and positive-intrinsic-negative (P-I-N) diodes is proposed. A pair of EBG structures are applied to generate sharp notch bands in the targeted frequency spectrum. Each EBG creates a traditional notch, while two regular notches are combined to make a quasi-perfect, sharp, notch band. Four P-I-N diodes are engraved into the EBG structures to enable notch band reconfigurability. By switching the operational condition of the four diodes, the UWB antenna can dynamically adjust its notching characteristics to enhance its adaptability to various communication standards and applications. The antenna can be reconfigured as a UWB (3–11.6 GHz) without any notch band, a UWB with a single sharp notch (either at WLAN or 5G), or a UWB with two quasi-perfect notch bands. Moreover, the antenna’s notch bands can also be switched from a traditional notch to a quasi-perfect notch and vice versa. To confirm the validity of the simulated outcomes, the proposed reconfigurable UWB antenna is fabricated and measured. The experimental findings are aligned closely with simulation results, and the antenna offers notch band reconfigurability. The antenna shows a consistently favorable radiation pattern and gain. The dimension of the presented antenna is 20 × 27 × 1.52 mm3 (0.45 λc × 0.33 λc × 0.025 λc, where λc is the wavelength in free space).
Full article
(This article belongs to the Special Issue Microwave Passive Components, 2nd Edition)
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Open AccessArticle
Grooving and Absorption on Substrates to Reduce the Bulk Acoustic Wave for Surface Acoustic Wave Micro-Force Sensors
by
Yang Feng, Haoda Yu, Wenbo Liu, Keyong Hu, Shuifa Sun, Zhen Yang and Ben Wang
Micromachines 2024, 15(5), 637; https://doi.org/10.3390/mi15050637 - 9 May 2024
Abstract
Improving measurement accuracy is the core issue with surface acoustic wave (SAW) micro-force sensors. An electrode transducer can stimulate not only the SAW but also the bulk acoustic wave (BAW). A portion of the BAW can be picked up by the receiving transducer,
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Improving measurement accuracy is the core issue with surface acoustic wave (SAW) micro-force sensors. An electrode transducer can stimulate not only the SAW but also the bulk acoustic wave (BAW). A portion of the BAW can be picked up by the receiving transducer, leading to an unwanted or spurious signal. This can harm the device’s frequency response characteristics, thereby potentially reducing the precision of the micro-force sensor’s measurements. This paper examines the influence of anisotropy on wave propagation, and it also performs a phase-matching analysis between interdigital transducers (IDTs) and bulk waves. Two solutions are shown to reduce the influence of BAW for SAW micro sensors, which are arranged with acoustic absorbers at the ends of the substrate and in grooving in the piezoelectric substrate. Three different types of sensors were manufactured, and the test results showed that the sidelobes of the SAW micro-force sensor could be effectively inhibited (3.32 dB), thereby enhancing the sensitivity and performance of sensor detection. The SAW micro-force sensor manufactured using the new process was tested and the following results were obtained: the center frequency was 59.83 MHz, the fractional bandwidth was 1.33%, the range was 0–1000 mN, the linearity was 1.02%, the hysteresis was 0.59%, the repeatability was 1.11%, and the accuracy was 1.34%.
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(This article belongs to the Special Issue Recent Advances in SAW Resonators)
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Open AccessArticle
Understanding the Effect of Dispersant Rheology and Binder Decomposition on 3D Printing of a Solid Oxide Fuel Cell
by
Man Yang, Santosh Kumar Parupelli, Zhigang Xu and Salil Desai
Micromachines 2024, 15(5), 636; https://doi.org/10.3390/mi15050636 - 9 May 2024
Abstract
Solid oxide fuel cells (SOFCs) are a green energy technology that offers a cleaner and more efficient alternative to fossil fuels. The efficiency and utility of SOFCs can be enhanced by fabricating miniaturized component structures within the fuel cell footprint. In this research
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Solid oxide fuel cells (SOFCs) are a green energy technology that offers a cleaner and more efficient alternative to fossil fuels. The efficiency and utility of SOFCs can be enhanced by fabricating miniaturized component structures within the fuel cell footprint. In this research work, the parallel-connected inter-digitized design of micro-single-chamber SOFCs (µ-SC-SOFCs) was fabricated by a direct-write microfabrication technique. To understand and optimize the direct-write process, the cathode electrode slurry was investigated. Initially, the effects of dispersant Triton X-100 on LSCF (La0.6Sr0.2Fe0.8Co0.2O3-δ) slurry rheology was investigated. The effect of binder decomposition on the cathode electrode lines was evaluated, and further, the optimum sintering profile was determined. Results illustrate that the optimum concentration of Triton X-100 for different slurries was around 0.2–0.4% of the LSCF solid loading. A total of 60% of solid loading slurries had high viscosities and attained stability after 300 s. In addition, 40–50% solid loading slurries had relatively lower viscosity and attainted stability after 200 s. Solid loading and binder affected not only the slurry’s viscosity but also its rheology behavior. Based on the findings of this research, a slurry with 50% solid loading, 12% binder, and 0.2% dispersant was determined to be the optimal value for the fabricating of SOFCs using the direct-write method. This research work establishes guidelines for fabricating the micro-single-chamber solid oxide fuel cells by optimizing the direct-write slurry deposition process with high accuracy.
Full article
(This article belongs to the Special Issue Recent Advances in Micro/Nano-Fabrication)
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