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Micromachines
Journal Prestige (SJR): 0.493  Citation Impact (citeScore): 2 Number of Followers: 2  Open Access journalISSN (Print) 2072-666X Published by MDPI  [258 journals]
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- Micromachines, Vol. 15, Pages 1060: Impact of Program–Erase
Operation Intervals at Different Temperatures on 3D Charge-Trapping
Triple-Level-Cell NAND Flash Memory Reliability
Authors: Xuesong Zheng, Yifan Wu, Haitao Dong, Yizhi Liu, Pengpeng Sang, Liyi Xiao, Xuepeng Zhan
First page: 1060
Abstract: Three-dimensional charge-trapping (CT) NAND flash memory has attracted extensive attention owing to its unique merits, including huge storage capacities, large memory densities, and low bit cost. The reliability property is becoming an important factor for NAND flash memory with multi-level-cell (MLC) modes like triple-level-cell (TLC) or quad-level-cell (QLC), which is seriously affected by the intervals between program (P) and erase (E) operations during P/E cycles. In this work, the impacts of the intervals between P&E cycling under different temperatures and P/E cycles were systematically characterized. The results are further analyzed in terms of program disturb (PD), read disturb (RD), and data retention (DR). It was found that fail bit counts (FBCs) during the high temperature (HT) PD process are much smaller than those of the room temperature (RT) PD process. Moreover, upshift error and downshift error dominate the HT PD and RT PD processes, respectively. To improve the memory reliability of 3D CT TLC NAND, different intervals between P&E operations should be adopted considering the operating temperatures. These results could provide potential insights to optimize the lifetime of NAND flash-based memory systems.
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091060
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1061: Recent Advances in
Phthalocyanine-Based Hybrid Composites for Electrochemical Biosensors
Authors: Keshavananda Prabhu Channabasavana Hundi Puttaningaiah, Jaehyun Hur
First page: 1061
Abstract: Biosensors are smart devices that convert biochemical responses to electrical signals. Designing biosensor devices with high sensitivity and selectivity is of great interest because of their wide range of functional operations. However, the major obstacles in the practical application of biosensors are their binding affinity toward biomolecules and the conversion and amplification of the interaction to various signals such as electrical, optical, gravimetric, and electrochemical signals. Additionally, the enhancement of sensitivity, limit of detection, time of response, reproducibility, and stability are considerable challenges when designing an efficient biosensor. In this regard, hybrid composites have high sensitivity, selectivity, thermal stability, and tunable electrical conductivities. The integration of phthalocyanines (Pcs) with conductive materials such as carbon nanomaterials or metal nanoparticles (MNPs) improves the electrochemical response, signal amplification, and stability of biosensors. This review explores recent advancements in hybrid Pcs for biomolecule detection. Herein, we discuss the synthetic strategies, material properties, working mechanisms, and integration methods for designing electrochemical biosensors. Finally, the challenges and future directions of hybrid Pc composites for biosensor applications are discussed.
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091061
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1062: Investigation of the Surface
Characteristics of GCr15 in Electrochemical Machining
Authors: Xuesong Liu, Guokang Su, Qingming Fan, Yongjun Zhang, Hua Chen, Chuanyun Zhang
First page: 1062
Abstract: Bearing steel (GCr15) is widely used in key parts of mechanical transmission for its excellent mechanical properties. Electrochemical machining (ECM) is a potential method for machining GCr15, as the machining process is the electrochemical dissolution of GCr15 regardless of its high hardness (>50 HRC). In ECM, NaNO3 solution is a popular electrolyte, as it has the ability to help in the nonlinear dissolution of many metallic alloy materials, making it useful for precision machining. However, due to high carbon content of GCr15, the electrochemical dissolution of GCr15 is unique, and there is always a black layer with high roughness on the machined surface, reducing the surface quality. In order to improve the electrochemical machining of GCr15 with a high surface quality, the surface characteristics of GCr15 in ECM were investigated. The anodic polarisation curve in the NaNO3 electrolyte was measured and electrochemical dissolution experiments were conducted with different current densities. SEM, XRD, and XPS were employed to analyse the surface morphology and composition formed on the machined surface at different current densities. The initial results showed that there were two parts (black part and bright part) formed on the machined surface when a short circuit occurred, and the test results suggested that the black part contained a mass of Fe3O4 while the bright part was composed of mainly Fe and Fe3C. Further investigation uncovered that a black flocculent layer (Fe3O4) always formed in a low current density (32 A/cm2) with high roughness. With the current density increased, the amount of black flocculent layer was reduced, and Fe3C particles appeared on the machined surface. When the current density reached 81 A/cm2, the entire flocculent oxide layer was removed, only some spherical Fe3C particles were inserted on the machined surface, and the roughness was reduced from Ra7.743 μm to Ra1.783 μm. In addition, due to exposed Fe3C particles on the machined surface, the corrosion resistance of the machined surface was significantly improved. Finally, circular arc grooves of high quality were well manufactured with current density of 81 A/cm2 in NaNO3 electrolyte.
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091062
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1063: Offsetting Dense Particle
Sedimentation in Microfluidic Systems
Authors: Tochukwu Dubem Anyaduba, Jesus Rodriguez-Manzano
First page: 1063
Abstract: Sedimentation is an undesirable phenomenon that complicates the design of microsystems that exploit dense microparticles as delivery tools, especially in biotechnological applications. It often informs the integration of continuous mixing modules, consequently impacting the system footprint, cost, and complexity. The impact of sedimentation is significantly worse in systems designed with the intent of particle metering or binary encapsulation in droplets. Circumventing this problem involves the unsatisfactory adoption of gel microparticles as an alternative. This paper presents two solutions—a hydrodynamic solution that changes the particle sedimentation trajectory relative to a flow-rate dependent resultant force, and induced hindered settling (i-HS), which exploits Richardson–Zaki (RZ) corrections of Stokes’ law. The hydrodynamic solution was validated using a multi-well fluidic multiplexing and particle metering manifold. Computational image analysis of multiplex metering efficiency using this method showed an average reduction in well-to-well variation in particle concentration from 45% (Q = 1 mL/min, n = 32 total wells) to 17% (Q = 10 mL/min, n = 48 total wells). By exploiting a physical property (cloud point) of surfactants in the bead suspension in vials, the i-HS achieved a 58% reduction in the sedimentation rate. This effect results from the surfactant phase change, which increases the turbidity (transient increase in particle concentration), thereby exploiting the RZ theories. Both methods can be used independently or synergistically to eliminate bead settling in microsystems or to minimize particle sedimentation
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091063
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1064: Democratizing Microreactor Technology
for Accelerated Discoveries in Chemistry and Materials Research
Authors: Tomomi Sato, Koji Masuda, Chikako Sano, Keiji Matsumoto, Hidetoshi Numata, Seiji Munetoh, Toshihiro Kasama, Ryo Miyake
First page: 1064
Abstract: Microreactor technologies have emerged as versatile platforms with the potential to revolutionize chemistry and materials research, offering sustainable solutions to global challenges in environmental and health domains. This survey paper provides an in-depth review of recent advancements in microreactor technologies, focusing on their role in facilitating accelerated discoveries in chemistry and materials. Specifically, we examine the convergence of microfluidics with machine intelligence and automation, enabling the exploitation of the cyber-physical environment as a highly integrated experimentation platform for rapid scientific discovery and process development. We investigate the applicability and limitations of microreactor-enabled discovery accelerators in various chemistry and materials contexts. Despite their tremendous potential, the integration of machine intelligence and automation into microreactor-based experiments presents challenges in establishing fully integrated, automated, and intelligent systems. These challenges can hinder the broader adoption of microreactor technologies within the research community. To address this, we review emerging technologies that can help lower barriers and facilitate the implementation of microreactor-enabled discovery accelerators. Lastly, we provide our perspective on future research directions for democratizing microreactor technologies, with the aim of accelerating scientific discoveries and promoting widespread adoption of these transformative platforms.
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091064
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1065: Development of Highly Sensitive and
Thermostable Microelectromechanical System Pressure Sensor Based on
Array-Type Aluminum–Silicon Hybrid Structures
Authors: Min Li, Yang Xiao, Jiahong Zhang, Qingquan Liu, Xianglong Jiang, Wenhao Hua
First page: 1065
Abstract: In order to meet the better performance requirements of pressure detection, a microelectromechanical system (MEMS) piezoresistive pressure sensor utilizing an array-type aluminum–silicon hybrid structure with high sensitivity and low temperature drift is designed, fabricated, and characterized. Each element of the 3 × 3 sensor array has one stress-sensitive aluminum–silicon hybrid structure on the strain membrane for measuring pressure and another temperature-dependent structure outside the strain membrane for measuring temperature and temperature drift compensation. Finite-element numerical simulation has been adopted to verify that the array-type pressure sensor has an enhanced piezoresistive effect and high sensitivity, and then this sensor is fabricated based on the standard MEMS process. In order to further reduce the temperature drift, a thermodynamic control system whose heating feedback temperature is measured by the temperature-dependent structure is adopted to keep the working temperature of the sensor constant by using the PID algorithm. The experiment test results show that the average sensitivity of the proposed sensor after temperature compensation reaches 0.25 mV/ (V kPa) in the range of 0–370 kPa, the average nonlinear error is about 1.7%, and the thermal sensitivity drift coefficient (TCS) is reduced to 0.0152%FS/°C when the ambient temperature ranges from −20 °C to 50 °C. The research results may provide a useful reference for the development of a high-performance MEMS array-type pressure sensor.
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091065
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1066: A Low-Power Optoelectronic Receiver IC
for Short-Range LiDAR Sensors in 180 nm CMOS
Authors: Shinhae Choi, Yeojin Chon, Sung Min Park
First page: 1066
Abstract: This paper presents a novel power-efficient topology for receivers in short-range LiDAR sensors. Conventionally, LiDAR sensors exploit complex time-to-digital converters (TDCs) for time-of-flight (ToF) distance measurements, thereby frequently leading to intricate circuit designs and persistent walk error issues. However, this work features a fully differential trans-impedance amplifier with on-chip avalanche photodiodes as optical detectors so that the need of the following post-amplifiers and output buffers can be eliminated, thus considerably reducing power consumption. Also, the combination of amplitude-to-voltage (A2V) and time-to-voltage (T2V) converters are exploited to replace the complicated TDC circuit. The A2V converter efficiently processes weak input photocurrents ranging from 1 to 50 μApp which corresponds to a maximum distance of 22.8 m, while the T2V converter handles relatively larger photocurrents from 40 μApp to 5.8 mApp for distances as short as 30 cm. The post-layout simulations confirm that the proposed LiDAR receiver can detect optical pulses over the range of 0.3 to 22.8 m with a low power dissipation of 10 mW from a single 1.8 V supply. This topology offers significant improvements in simplifying the receiver design and reducing the power consumption, providing a more efficient and accurate solution that is highly suitable for short-range LiDAR sensor applications.
Citation: Micromachines
PubDate: 2024-08-23
DOI: 10.3390/mi15091066
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1067: Design and Validation of a Monte Carlo
Method for the Implementation of Noninvasive Wearable Devices for HbA1c
Estimation Considering the Skin Effect
Authors: Tae-Ho Kwon, Shifat Hossain, Mrinmoy Sarker Turja, Ki-Doo Kim
First page: 1067
Abstract: To diagnose diabetes early or to maintain stable blood glucose levels in diabetics, blood glucose levels should be frequently checked. However, the only way to check blood glucose levels regularly is to use invasive methods, such as pricking the fingertip or using a minimally invasive patch. These invasive methods pose several problems, including being painful and potentially causing secondary infections. This study focuses on noninvasively measuring glycated hemoglobin (HbA1c) using PPG signals. In particular, the study relates to a method and a hardware design technology for removing noise that may be present in a PPG signal due to skin contact with a noninvasive HbA1c measurement device. The proposed HbA1c measurement device consists of the first sensor (PPG sensor) module including an optical barrier and the second sensor (cylindrical sensor) module for removing the skin effect. We have developed a Monte Carlo method to implement accurate, noninvasive HbA1c measurement by considering different skin properties among different subjects. Implementing this model in wearable devices will allow end users to not only monitor their glycated hemoglobin levels but also control diabetes with higher accuracy without needing any blood samples. This will be a groundbreaking advancement in modern wearable medical devices.
Citation: Micromachines
PubDate: 2024-08-24
DOI: 10.3390/mi15091067
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1068: Development of a Novel
Electrostatic-Based Bioaerosol Sampler
Authors: Zirui Pang, Lulu Shi, Wei Liu, Wenru Liu, Xin Tian, Mingyu Wang, Jifang Tao
First page: 1068
Abstract: On-site bioaerosol monitoring is essential for estimating microbial biomass and mitigating the risk of infection induced by aerosol transmission. This study introduces a novel electrostatic bioaerosol sampler, which is fabricated by the use of 3D printing, for rapid bioaerosol collection. Aerosol particles were charged and enriched in the sampler. Relationships between particle sizes and collection efficiencies under varying charging voltages were established using a charging model. The design of the sampler was optimized using commercial software, incorporating electrostatic field analysis, computational fluid dynamics (CFD), and particle trajectory simulations. To validate the sampler’s collection efficiency, polystyrene (PS) spheres in an aerosol dispenser were atomized into an aerosol. The sampler collection efficiency exceeded 90% for particles larger than 1.2 μm under an applied voltage of 4.7 kV and an airflow rate of 2 L/min. The enrichment capacity was greater than 153,000 for particles larger than 1.2 μm under an applied voltage of 4.7 kV and an airflow rate of 8 L/min. With the merits of low cost, miniaturization, and high collection efficiency, the sampler can be used to collect samples on-site and in remote areas to verify the pathogens and reduce the risk of infection through aerosol transmission.
Citation: Micromachines
PubDate: 2024-08-24
DOI: 10.3390/mi15091068
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1069: Model-Based Optimization of
Solid-Supported Micro-Hotplates for Microfluidic Cryofixation
Authors: Daniel B. Thiem, Greta Szabo, Thomas P. Burg
First page: 1069
Abstract: Cryofixation by ultra-rapid freezing is widely regarded as the gold standard for preserving cell structure without artefacts for electron microscopy. However, conventional cryofixation technologies are not compatible with live imaging, making it difficult to capture dynamic cellular processes at a precise time. To overcome this limitation, we recently introduced a new technology, called microfluidic cryofixation. The principle is based on micro-hotplates counter-cooled with liquid nitrogen. While the power is on, the sample inside a foil-embedded microchannel on top of the micro-hotplate is kept warm. When the heater is turned off, the thermal energy is drained rapidly and the sample freezes. While this principle has been demonstrated experimentally with small samples (<0.5 mm2), there is an important trade-off between the attainable cooling rate, sample size, and heater power. Here, we elucidate these connections by theoretical modeling and by measurements. Our findings show that cooling rates of 106 K s−1, which are required for the vitrification of pure water, can theoretically be attained in samples up to ∼1 mm wide and 5m thick by using diamond substrates. If a heat sink made of silicon or copper is used, the maximum thickness for the same cooling rate is reduced to ∼3 μm. Importantly, cooling rates of 104 K s−1 to 105 K s−1 can theoretically be attained for samples of arbitrary area. Such rates are sufficient for many real biological samples due to the natural cryoprotective effect of the cytosol. Thus, we expect that the vitrification of millimeter-scale specimens with thicknesses in the 10m range should be possible using micro-hotplate-based microfluidic cryofixation technology.
Citation: Micromachines
PubDate: 2024-08-24
DOI: 10.3390/mi15091069
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1070: Acoustic Transmission Measurements for
Extracting the Mechanical Properties of Complex 3D MEMS Transducers
Authors: Dennis Becker, Moritz Littwin, Achim Bittner, Alfons Dehé
First page: 1070
Abstract: Recent publications on acoustic MEMS transducers present a new three-dimensional folded diaphragm that utilizes buried in-plane vibrating structures to increase the active area from a small chip volume. Characterization of the mechanical properties plays a key role in the development of new MEMS transducers, whereby established measurement methods are usually tailored to structures close to the sample surface. In order to access the lateral vibrations, extensive and destructive sample preparation is required. This work presents a new passive measurement technique that combines acoustic transmission measurements and lumped-element modelling. For diaphragms of different lengths, compliances between 0.08 × 10−15 and 1.04 × 10−15 m³/Pa are determined without using destructive or complex preparations. In particular, for lengths above 1000 µm, the results differ from numerical simulations by only 4% or less.
Citation: Micromachines
PubDate: 2024-08-24
DOI: 10.3390/mi15091070
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1071: The Microstructure and Properties of
Ni60/60% WC Wear-Resistant Coatings Prepared by Laser-Directed Energy
Deposition
Authors: Husen Yang, Wen Li, Yichun Liu, Fengxian Li, Jianhong Yi, Jürgen Eckert
First page: 1071
Abstract: Ni60/60% WC composite coatings with a good surface roughness and high mechanical properties were successfully prepared on 316L stainless steel substrate by laser-directed energy deposition (LDED) technology. The effects of laser power on the microstructural evolution and mechanical properties of the Ni60/60% WC composite coating were investigated. The relationships between the chemical composition, the microstructure, the hardness, and the friction wear resistance of the composite coatings were characterized and investigated. The results show that the laser power had a significant effect on the energy input, which determined the melting extent of the Ni60 phases around the WC particles and the bonding strength between the reinforcements and the matrix, as well as the bonding strength between the substrate and the coatings. With an increase in the laser power from 800 W to 1400 W, the average hardness of the coating surface increased due to the increased densification of the deposited coatings and then decreased due to grain coarsening under a high energy input. The average coefficient of friction of the coatings decreased gradually to 0.383 at 1000 W, showing a minimum wear of 0.00013 mm2 at 1200 W. The main wear mechanisms on the coated surfaces were adhesive wear and abrasive wear. Moreover, the coatings deposited at 1200 W exhibited better forming quality and wear resistance. This work suggests that the processing parameters during LDED can be optimized to prepare Ni60/60% WC wear-resistant coatings with excellent mechanical properties.
Citation: Micromachines
PubDate: 2024-08-25
DOI: 10.3390/mi15091071
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1072: A True Random Number Generator Design
Based on the Triboelectric Nanogenerator with Multiple Entropy Sources
Authors: Shuaicheng Guo, Yuejun Zhang, Ziyu Zhou, Lixun Wang, Zhuo Ruan, Yu Pan
First page: 1072
Abstract: The triboelectric nanogenerator (TENG) has the potential to serve as a high-entropy energy harvester, enabling the self-powered operation of Internet of Things (IoT) devices. True random number generator (TRNG) is a common feature of encryption used in IoT data communication, ensuring the security of transmitted information. The benefits of multiplexing TENG and TRNG in resource-constrained IoT devices are substantial. However, current designs are limited by the usage scenarios and throughput of the TRNG. Specifically, we propose a structurally and environmentally friendly design based on the contact–separation structure, integrating heat fluctuation and charge decay as entropy sources. Furthermore, filtering and differential algorithms are recommended for data processing based on TENG characteristics to enhance randomness. Finally, a TENG-based TRNG is fabricated, and its performance is verified. Test results demonstrate a random number throughput of 25 Mbps with a randomness test pass rate approaching 99%, demonstrating suitability for resource-constrained IoT applications.
Citation: Micromachines
PubDate: 2024-08-25
DOI: 10.3390/mi15091072
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1073: Machine Learning-Guided Cycle Life
Prediction for Electrochromic Devices Based on Deuterium and Water Mixing
Solvent
Authors: Yitong Wu, Sifan Kong, Qingxin Yao, Muyun Li, Huayi Lai, Duoyu Sun, Qingyue Cai, Zelin Qiu, Honglong Ning, Yong Zhang
First page: 1073
Abstract: Electrochromic devices have demonstrated considerable potential in a range of applications, including smart windows and automotive rearview mirrors. However, traditional cycle life testing methods are time-consuming and require significant resources to process a substantial amount of generated data, which presents a significant challenge and remains an urgent issue to be addressed. To address this challenge, we proposed the use of Long Short-Term Memory (LSTM) networks to construct a prediction model of the cycle life of electrochromic devices and introduced an interpretable analysis method to further analyze the model’s predictive capabilities. The original dataset used for modeling was derived from preliminary experiments conducted under 1000 cycles of six devices prepared with varying mixing ratios of heavy water (D2O). Furthermore, validation experiments confirmed the feasibility of the D2O mixing strategy, with 83% of the devices exhibiting a high initial transmittance modulation amplitude (ΔT = 43.95%), a rapid response time (tc = 7 s and tb = 8 s), and excellent cyclic stability (ΔT = 44.92% after 1000 cycles). This study is the first to use machine learning techniques to predict the cycle life of electrochromic devices while proposing performance enhancement and experimental time savings for inorganic all-liquid electrochromic devices.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091073
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1074: Exploring Electrochemical Direct
Writing Machining of Patterned Microstructures on Zr702 with
Polyacrylamide Polymer Electrolyte
Authors: Junfeng He, Wenjie Chen, Junjie Wang, Ming Wu, Li Zhou, Ri Chen, Huazhuo Liang
First page: 1074
Abstract: Zirconium alloys possess excellent wear resistance, which ensures the durability and longevity of the components, making them widely used in medical and other fields. To enhance the functionality of these materials, it is often necessary to fabricate functional microstructures on their surfaces. Electrochemical machining (ECM) techniques demonstrate excellent machining performance for these metals, particularly in the processing of microstructures on complex curved surfaces. However, ECM often faces challenges due to the fluid nature of the electrolyte, resulting in low machining accuracy and localization. This paper proposes a novel method for fabricating complex patterned microstructures using a maskless electrochemical direct writing technique with a polyacrylamide (PAM) polymer electrolyte. By leveraging the non-Newtonian properties of PAM, this method effectively confines the electrolyte to specific areas, thus addressing the issue of poor localization in traditional ECM and reducing stray corrosion. To elucidate the electrochemical removal mechanism of Zr702 in the presence of PAM, polarization curves, viscosity characteristics, and current efficiency parameters were analyzed. Additionally, an experimental study was conducted using a custom-designed nozzle structure. The results showed that the PAM electrolyte could effectively reduce the EF, positively impacting machining accuracy and localization. By controlling the nozzle’s motion trajectory, complex microstructures were successfully fabricated through direct writing, demonstrating promising application prospects.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091074
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1075: Parametric Synthesis of Single-Stage
Lattice-Type Acoustic Wave Filters and Extended Multi-Stage Design
Authors: Wei-Hsien Tseng, Ruey-Beei Wu
First page: 1075
Abstract: This study proposes a single-stage lattice-type acoustic filter using an analytical solution method for either a narrow passband filter or a wider passband filter using two kinds of parameter assignments in the Butterworth–Van Dyke (BVD) model. To achieve the goal of a large bandwidth or high return loss, two first-order all-pass conditions are used. For multi-stage lattice-type filters, the cost function is defined and design parameters are extracted by using pattern search, while the initial values are provided through single-stage design to shorten optimization time and allow convergence to a better solution. This method provides the S-parameter frequency response for the filter on the YX 42° cut angle of lithium tantalate (electromechanical coupling coefficient of about 6%) that can meet the system specifications as much as possible. Finally, the three-stage lattice-type was applied to various 5G bands with a fractional bandwidth of 2–5%, resulting in a passband return loss of 10 dB and an out-of-band rejection of 40 dB or more.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091075
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1076: Low-Power Driving Waveform Design for
Improving the Display Effect of Electrophoretic Electronic Paper
Authors: Shanling Lin, Jianhao Zhang, Jia Wei, Xinxin Xie, Shanhong Lv, Ting Mei, Tingyu Wang, Bipeng Cai, Wenjie Mao, Tailiang Guo, Jianpu Lin, Zhixian Lin
First page: 1076
Abstract: To address the high power consumption associated with image refresh operations in EPDs, this paper proposes a low-power driving waveform that reduces the refresh power of EPDs by lowering the system’s peak power. Compared to traditional waveforms, this waveform first activates the particles before erasing them, thus reducing voltage polarity changes. Additionally, it introduces a specific duration of 0 V voltage during the activation phase based on the physical characteristics of the electrophoretic particles to reduce the voltage span. Finally, a particular duration of 0 V voltage is introduced during the erasure phase to minimize the voltage span while ensuring the stability and consistency of the reference gray scale. The experimental results demonstrate that, in standard power tests, the new driving waveform reduces the power fluctuation value by 1.33% and the energy fluctuation value by 37.24% compared to the traditional driving waveform. This reduction in refresh power also mitigates screen flicker and ghosting phenomena.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091076
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1077: A V-Band Wideband Power Amplifier with
High Gain in a 130 nm SiGe BiCMOS Process
Authors: Jianing Hu, Jialong Wan, Yi Shen, Wei Zhao, Jiang Luo
First page: 1077
Abstract: This paper introduces a high-gain wideband power amplifier (PA) designed for V-band applications, operating across 52 to 65 GHz. The proposed PA design employs a combination of techniques, including pole-gain distribution, base-capacitive peaking, and the parallel configuration of multiple small-sized transistors. These strategies enable significant bandwidth extension while maintaining high gain, substantial output power, and a compact footprint. A two-stage PA using the combination technique was developed and fabricated in a 130 nm SiGe BiCMOS process. The PA prototype achieved a peak gain of 27.3 dB at 64 GHz, with a 3 dB bandwidth exceeding 13 GHz and a fractional bandwidth greater than 22.2%. It delivered a maximum saturated output power of 19.7 dBm and an output 1 dB compression point of 18 dBm. Moreover, the PA chip occupied a total silicon area of 0.57 mm2, including all testing pads with a compact core size of 0.198 mm2.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091077
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1078: Characterization of Micro-Holes
Drilled Using a UV Femtosecond Laser in Modified Polyimide Flexible
Circuit Boards
Authors: Lijuan Zheng, Shuzhan Lin, Huijuan Lu, Bing Huang, Yu Liu, Jun Wang, Xin Wei, Jun Wang, Chengyong Wang
First page: 1078
Abstract: Modified polyimide (MPI) flexible printed circuits (FPCs) are used as chip carrier boards. The quality of the FPC directly affects the reliability of the integrated circuit. Furthermore, micro-holes are critical components of FPCs. In this study, an ultraviolet (UV) femtosecond laser is used to drill micro-holes in double-layer flexible circuit boards with MPI as the substrate. The morphology of the micro-hole wall in the copper foil and MPI layer is observed, and the effects of the laser processing parameters on the diameter and depth of the micro-holes are analyzed. The drilling process and mechanism of micro-holes obtained using a UV femtosecond laser in MPI FPCs are discussed. The results show that the morphology of femtosecond laser-machined copper is closely related to the laser energy, and a periodic structure is observed during the machining process. Copper, MPI, and copper oxides are the most common molten deposits in micro-holes during drilling. The depth of the micro-holes increases with an increase in the energy of a single pulse, scanning time, and scanning overlap rate of the laser beam. However, the diameter exhibits no discernible alteration. The material removal rate increased significantly when laser processing was applied to the MPI resin layer.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091078
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1079: Frequency Detection for String
Instruments Using 1D-2D Non-Contact Mode Triboelectric Sensors
Authors: Inkyum Kim, Hyunwoo Cho, Daewon Kim
First page: 1079
Abstract: The proliferation of small electronic devices has significantly increased the demand for self-powered sensors. This study introduces a triboelectric frequency sensor (TFS) that combines the frequency-responsive characteristics of triboelectric nanogenerators with a simple one-dimensional structure for sustainable vibration measurement. This sensor is specifically designed to aid in the tuning of string instruments, capable of detecting frequency responses up to 330 Hz generated by string vibrations. Structural optimization was achieved by setting a non-contact mode with a gap distance of 3 mm and utilizing perfluoroalkoxy alkane (PFA) as the contact dielectric material. The TFS exhibits dynamic response characteristics by varying the vibrating frequency and the tension of the string, facilitated by a custom-built testing setup. Frequency data captured by the sensor can be visualized on a monitor through the integration of a microcontroller unit (MCU) and dedicated coding. The practical applicability and effectiveness of this sensor in real-world scenarios are demonstrated experimentally. This innovation represents a significant step forward in the development of self-sustaining sensing technologies for precision instrument tuning.
Citation: Micromachines
PubDate: 2024-08-26
DOI: 10.3390/mi15091079
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1080: Photonics-Based Multifunction System
for Radar Signal Transmit-Receive Processing and Frequency Measurement
Authors: Dengcai Yang, Ya Zhang, Feng Yang, Mei Yang, Yinhua Cao
First page: 1080
Abstract: A novel photonic-assisted multifunctional radar system was proposed and experimentally investigated. This system can simultaneously achieve frequency-doubled linear frequency modulation (LFM) signal generation, de-chirp reception, self-interference cancellation, and frequency measurement in an integrated transmit-receive radar. First, a high-frequency and broadband LO signal was obtained with photonic frequency doubling, which improved the center frequency and bandwidth of the radar detection system. Then, photonic-assisted interference cancellation was used to reduce the impact of interference signals in radar de-chirp reception. Finally, the microwave frequency measurement was achieved by establishing a mapping relationship between the envelope response time of the intermediate frequency (IF) electrical filter and the microwave frequency to be tested. Both theoretical and experimental investigations were performed. The results showed that an LFM signal with a frequency range of 12–18 GHz was obtained with photonic frequency doubling. Photonic-assisted self-interference cancellation reduced the impact of interference signals in radar de-chirp reception by more than 12.1 dB for an LFM signal bandwidth of 6 GHz. In the frequency measurement module, the difference between the frequency to be tested, generated by the external signal source, and that calculated in the experiment is the measurement error, and a measurement resolution better than 14 MHz was achieved in the range of 12.14 GHz–18.14 GHz. The proposed system is suitable for miniaturized multifunctional radar signal processing systems with continuous operation of transmitting and receiving antennas in unmanned aerial vehicles (UAVs), automotive radar, relatively close spatial locations, and so on. In addition, it can simplify the system structure and reduce space occupation.
Citation: Micromachines
PubDate: 2024-08-27
DOI: 10.3390/mi15091080
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1081: Textile Bandwidth-Enhanced Half-Mode
Substrate-Integrated Cavity Antenna Based on Embroidered Shorting Vias
Authors: Feng-Xue Liu, Fan-Yu Meng, Yu-Jia Chen, Zhou-Hao Gao, Jie Cui, Le Zhang
First page: 1081
Abstract: A textile bandwidth-enhanced half-mode substrate-integrated cavity (HMSIC) antenna based on embroidered shorting vias is designed. Based on the simulated results of the basic HMSIC antenna, two embroidered hollow posts with square cross-sections are added as shorting vias at the intersections of the zero-E traces of the TM210HM and TM020HM modes to shift the TM010HM-mode band to merge with the bands of the higher-order modes for bandwidth enhancement. A prototype is practically fabricated based on computerized embroidery techniques. Measurement results show that the prototype is of an expanded −10 dB impedance band of 4.87~6.17 GHz (23.5% fractional bandwidth), which fully covers the 5 GHz wireless local area network (WLAN) band. The simulated radiation efficiency and maximum gain of the proposed antenna are above 97% and 7.6 dBi, respectively. Furthermore, simulations and measurements prove its robust frequency response characteristic in the proximity of the human tissues or in bending conditions, and the simulations of the specific absorption rate (SAR) prove its electromagnetic safety on the human body.
Citation: Micromachines
PubDate: 2024-08-27
DOI: 10.3390/mi15091081
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1082: Enhancing 3D Printing Copper-PLA
Composite Fabrication via Fused Deposition Modeling through Statistical
Process Parameter Study
Authors: Mahmoud Moradi, Omid Mehrabi, Fakhir A. Rasoul, Anas Abid Mattie, Friedemann Schaber, Rasoul Khandan
First page: 1082
Abstract: The rapid advancement of additive manufacturing (AM) technologies has provided new avenues for creating three-dimensional (3D) parts with intricate geometries. Fused Deposition Modeling (FDM) is a prominent technology in this domain, involving the layer-by-layer fabrication of objects by extruding a filament comprising a blend of polymer and metal powder. This study focuses on the FDM process using a filament of Copper–Polylactic Acid (Cu-PLA) composite, which capitalizes on the advantageous properties of copper (high electrical and thermal conductivity, corrosion resistance) combined with the easily processable thermoplastic PLA material. The research delves into the impact of FDM process parameters, specifically, infill percentage (IP), infill pattern (P), and layer thickness (LT) on the maximum failure load (N), percentage of elongation at break, and weight of Cu-PLA composite filament-based parts. The study employs the response surface method (RSM) with Design-Expert V11 software. The selected parameters include infill percentage at five levels (10, 20, 30, 40, and 50%), fill patterns at five levels (Grid, Triangle, Tri-Hexagonal, Cubic-Subdivision, and Lines), and layer thickness at five levels (0.1, 0.2, 0.3, 0.4, and 0.5 mm). Also, the optimal factor values were obtained. The findings highlight that layer thickness and infill percentage significantly influence the weight of the samples, with an observed increase as these parameters are raised. Additionally, an increase in layer thickness and infill percentage corresponds to a higher maximum failure load in the specimens. The peak maximum failure load (230 N) is achieved at a 0.5 mm layer thickness and Tri-Hexagonal pattern. As the infill percentage changes from 10% to 50%, the percentage of elongation at break decreases. The maximum percentage of elongation at break is attained with a 20% infill percentage, 0.2 mm layer thickness, and 0.5 Cubic-Subdivision pattern. Using a multi-objective response optimization, the layer thickness of 0.152 mm, an infill percentage of 32.909%, and a Grid infill pattern was found to be the best configuration.
Citation: Micromachines
PubDate: 2024-08-27
DOI: 10.3390/mi15091082
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1083: Branch Waveguide Couplers with a
frequency of 510 GHz for Terahertz Transmit/Receive Isolation Applications
Authors: Hao Li, Dehai Zhang, Jin Meng, Li Wang
First page: 1083
Abstract: To address the requirement of functioning as a transmit/receive isolation device in terahertz transceiver systems, in this paper, we present two high−isolation multi−branch waveguide directional couplers operating at a center frequency of 510 GHz. One is a high−performance five−branch directional coupler, and the other is a new type of three−branch waveguide coupler with lower processing difficulty. Both couplers were fabricated using low−cost CNC milling technologies. The performance of these couplers was verified through measurement results, demonstrating high isolation at the center frequency.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091083
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1084: Ultra-Broadband Mode (De)Multiplexer
on Thin-Film Lithium Niobate Platform Adopting Phase Control Theory
Authors: Kun Yin, Wenting Jiao, Lin Wang, Shiqiang Zhu
First page: 1084
Abstract: Mode (de)multiplexers (MDMs) serve as critical foundational elements within systems for facilitating high-capacity communication, relying on mode conversions achieved through directional coupler (DC) structures. However, DC structures are challenged by dispersion issues for broadband mode coupling, particularly for high-order modes. In this work, based on the principles of phase control theory, we have devised an approach to mitigate the dispersion challenges, focusing on a thin-film lithium niobate-on-onsulator (LNOI) platform. This solution involves integrating a customized inverse-dispersion section into the device architecture, offsetting minor phase shifts encountered during the mode coupling process. By employing this approach, we have achieved broadband mode conversion from TE0 to TE1 and TE0 to TE2 within a 300 nm wavelength range, and the maximum deviations were maintained below −0.68 dB and −0.78 dB, respectively. Furthermore, the device exhibited remarkably low crosstalk, reaching down to −26 dB.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091084
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1085: Temperature Effects in Packaged RF
MEMS Switches with Optimized Gold Electroplating Process
Authors: Lifeng Wang, Lili Jiang, Ning Ma, Xiaodong Huang
First page: 1085
Abstract: Due to its excellent electrical performance, mechanical reliability, and thermal stability, electroplated gold is still the most commonly used material for movable beams in RF MEMS switches. This paper investigates the influence of process conditions on the quality and growth rate of gold electroplating, and the optimized process parameters for the gold electroplating process are obtained. The characterization of the optimized electroplated gold layer shows that it has small surface roughness and excellent thermal stability. With this optimized gold electroplating process, the RF MEMS switches are fabricated and hermetic packaged. In order to obtain the temperature environment adaptability of the packaged switch, the influence of working temperature is studied. The temperature effects on mechanical performance (includes pull-in voltage and lifetime) and RF performance (includes insertion loss and isolation) are revealed.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091085
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1086: Robust Input Shaping Commands with
First-Order Actuators
Authors: Yoon-Gyung Sung, Seongjun Lee
First page: 1086
Abstract: This paper presents robust input shaping commands with first-order actuators utilizing a classical robust input shaper for practical applications in input shaping technology. An ideal input shaping command can deviate due to actuator dynamics so that the modified command has a detrimental effect on the performance of oscillation reduction in feedforward control applications. A zero-vibration-derivative (ZVDF) shaper with first-order actuators is analytically proposed using a phasor–vector approach, an exponential function for the approximation of the dynamic response of first-order actuators and the usage of the ZVD shaper. In addition, an equivalent transformation is utilized based on the superposition principle for the convenient inclusion of first-order actuator dynamics and is applied to the individual segment input command. The residual deflection and robustness of the proposed robust input shaping commands are numerically evaluated and compared with those of a conventional ZVD shaper with respect to the parameter uncertainties of flexible systems and actuators. The robust input shaping commands that are possible with first-order actuators are experimentally validated, presenting a better robustness and residual deflection reduction performance than the classical ZVD shaper on a mini bridge crane.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091086
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1087: Residual Stress and Warping Analysis
of the Nano-Silver Pressureless Sintering Process in SiC Power Device
Packaging
Authors: Wenchao Tian, Dexin Li, Haojie Dang, Shiqian Liang, Yizheng Zhang, Xiaojun Zhang, Si Chen, Xiaochuan Yu
First page: 1087
Abstract: Chip bonding, an essential process in power semiconductor device packaging, commonly includes welding and nano-silver sintering. Currently, most of the research on chip bonding technology focuses on the thermal stress analysis of tin–lead solder and nano-silver pressure-assisted sintering, whereas research on the thermal stress analysis of the nano-silver pressureless sintering process is more limited. In this study, the pressureless sintering process of nano-silver was studied using finite element software, with nano-silver as an interconnect material. Using the control variable method, we analyzed the influences of sintering temperature, cooling rate, solder paste thickness, and solder paste area on the residual stress and warping deformation of power devices. In addition, orthogonal experiments were designed to optimize the parameters and determine the optimal combination of the process parameters. The results showed that the maximum residual stress of the module appeared on the connection surface between the power chip and the nano-silver solder paste layer. The module warping deformation was convex warping. The residual stress of the solder layer increased with the increase in sintering temperature and cooling rate. It decreased with the increase in coating thickness. With the increase in the coating area, it showed a wave change. Each parameter influenced the stress of the solder layer in this descending order: sintering temperature, cooling rate, solder paste area, and solder paste thickness. The residual stress of the nano-silver layer was 24.83 MPa under the optimal combination of the process parameters and was reduced by 29.38% compared with the original value of 35.162 MPa.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091087
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1088: Off-Stoichiometry Thiol-Ene (OSTE)
Micro Mushroom Forest: A Superhydrophobic Substrate
Authors: Haonan Li, Muyang Zhang, Yeqian Liu, Shangneng Yu, Xionghui Li, Zejingqiu Chen, Zitao Feng, Jie Zhou, Qinghao He, Xinyi Chen, Huiru Zhang, Jiaen Zhang, Xingwei Zhang, Weijin Guo
First page: 1088
Abstract: Superhydrophobic surfaces have been used in various fields of engineering due to their resistance to corrosion and fouling and their ability to control fluid movement. Traditionally, superhydrophobic surfaces are fabricated via chemical methods of changing the surface energy or mechanical methods of controlling the surface topology. Many of the conventional mechanical methods use a top-to-bottom scheme to control the surface topolopy. Here, we develop a novel fabrication method of superhydrophobic substrates using a bottom-to-top scheme via polymer OSTE, which is a prototyping polymer material developed for the fabrication of microchips due to its superior photocuring ability, mechanical properties, and surface modification ability. We fabricate a superhydrophobic substrate by OSTE–OSTE micro mushroom forest via a two-step lithography process. At first, we fabricate an OSTE pillar forest as the mushroom stems; then, we fabricate the mushroom heads via backside lithography with diffused UV light. Such topology and surface properties of OSTE render these structures superhydrophobic, with water droplets reaching a contact angle of 152.9 ± 0.2°, a sliding angle of 4.1°, and a contact angle hysteresis of less than 0.5°. These characteristics indicate the promising potential of this substrate for superhydrophobic applications.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091088
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 1089: Optical Properties and Growth
Characteristics of 8-Quinolinolato Lithium (Liq) Nano-Layers Deposited by
Gas Transport Deposition
Authors: Alexandros Zachariadis, Michalis Chatzidis, Despoina Tselekidou, Olaf Wurzinger, Dietmar Keiper, Peter K. Baumann, Michael Heuken, Kyparisis Papadopoulos, Argiris Laskarakis, Stergios Logothetidis, Maria Gioti
First page: 1089
Abstract: Organometallic complexes containing reactive alkali metals, such as lithium (Li), represent a promising material approach for electron injection layers and electron transport layers (EILs and ETLs) to enhance the performance of Organic Light-Emitting Diodes (OLEDs). 8-Quinolinolato Lithium (Liq) has shown remarkable potential as an EIL and ETL when conveyed in very thin films. Nevertheless, the deposition of nano-layers requires precise control over both thickness and morphology. In this work, we investigate the optical properties and morphological characteristics of Liq thin films deposited via Organic Vapor Phase Deposition (OVPD). Specifically, we present our methodology for analyzing the measured pseudodielectric function <ε(ω)> using Spectroscopic Ellipsometry (SE), alongside the nano-topography of evaporated Liq nano-layers using Atomic Force Microscopy (AFM). This information can contribute to the understanding of the functionality of this material, since ultra-thin Liq interlayers can significantly increase the operational stability of OLED architectures.
Citation: Micromachines
PubDate: 2024-08-28
DOI: 10.3390/mi15091089
Issue No: Vol. 15, No. 9 (2024)
- Micromachines, Vol. 15, Pages 990: Raman Investigation on Silicon Nitride
Chips after Soldering onto Copper Substrates
Authors: Claudia Mezzalira, Fosca Conti, Danilo Pedron, Raffaella Signorini
First page: 990
Abstract: The unique electrical properties of silicon nitride have increased the applications in microelectronics, especially in the manufacture of integrated circuits. Silicon nitride is mainly used as a passivation barrier against water and sodium ion diffusion and as an electrical insulator between polysilicon layers in capacitors. The interface with different materials, like semiconductors and metals, through soldering may induce residual strains in the final assembly. Therefore, the dentification and quantification of strain becomes strategically important in optimizing processes to enhance the performance, duration, and reliability of devices. This work analyzes the thermomechanical local strain of semiconductor materials used to realize optoelectronic components. The strain induced in the β-Si3N4 chips by the soldering process performed with AuSn pre-formed on copper substrates is investigated by Raman spectroscopy in a temperature range of −50 to 180 °C. The variation in the position of the E1g Raman peak allows the calculation of the local stress present in the active layer, from which the strain induced during the assembly process can be determined. The main reason for the strain is attributed to the differences in thermal expansion coefficients among the various materials involved, particularly between the chip, the interconnection material, and the substrate. Micro-Raman spectroscopy allows for the assessment of how different materials and assembly processes impact the strain, enabling more informed decisions to optimize the overall device structure.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080990
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 991: A Novel Sensible Smart Mask Using Micro
Thermal-Electric Energy Conversion Elements
Authors: Yun Zhang, Zonglin Xiao, Binggang Liu, Xiaoming Ren, Cirui Liu
First page: 991
Abstract: In poor sanitary conditions, people need to wear masks to protect the health of their respiratory system. Meanwhile, it is necessary for patients with respiratory diseases to have real-time measurement on respiratory rate when wearing masks. Thermoelectric generation provides a new approach and method for powering and sensing small low-power devices, and has good application prospects in smart masks. In view of this, a novel sensible smart mask using micro thermal-electric energy conversion elements (TECE) is proposed in this paper, which can detect and display the respiratory rate in real time. First, the temperature conversion characteristic of micro TECE represented by the thermoelectric generator module is analyzed. Second, the respiratory characteristics of the human body are studied, and the respiratory rate sensing effect based on micro TECEs is analyzed and verified. Then, a sensible smart mask, which can show respiratory rate in real time, is developed by integrating MCU and OLED module. Finally, human respiratory rate experiments are conducted, the experimental results verified the effectiveness and accuracy of the proposed sensible smart mask.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080991
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 992: Customization of Computed Tomography
Radio-Opacity in 3D-Printed Contrast-Injectable Tumor Phantoms
Authors: Yuktesh Kalidindi, Aravinda Krishna Ganapathy, Liam Cunningham, Adriene Lovato, Brian Albers, Anup S. Shetty, David H. Ballard
First page: 992
Abstract: Medical Imaging Phantoms (MIPs) calibrate imaging devices, train medical professionals, and can help procedural planning. Traditional MIPs are costly and limited in customization. Additive manufacturing allows for customizable, patient-specific phantoms. This study examines the CT attenuation characteristics of contrast-injectable, chambered 3D-printed phantoms to optimize tissue-mimicking capabilities. A MIP was constructed from a CT of a complex pelvic tumor near the iliac bifurcation. A 3D reconstruction of these structures composed of three chambers (aorta, inferior vena cava, tumor) with ports for contrast injection was 3D printed. Desired attenuations were 200 HU (arterial I), 150 HU (venous I), 40 HU (tumor I), 150 HU (arterial II), 90 HU (venous II), and 400 HU (tumor II). Solutions of Optiray 350 and water were injected, and the phantom was scanned on CT. Attenuations were measured using ROIs. Mean attenuation for the six phases was as follows: 37.49 HU for tumor I, 200.50 HU for venous I, 227.92 HU for arterial I, 326.20 HU for tumor II, 91.32 HU for venous II, and 132.08 HU for arterial II. Although the percent differences between observed and goal attenuation were high, the observed relative HU differences between phases were similar to goal HU differences. The observed attenuations reflected the relative concentrations of contrast solutions used, exhibiting a strong positive correlation with contrast concentration. The contrast-injectable tumor phantom exhibited a useful physiologic range of attenuation values, enabling the modification of tissue-mimicking 3D-printed phantoms even after the manufacturing process.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080992
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 993: A Study on the Dynamic Switching
Characteristics of p-GaN HEMT Power Devices
Authors: Chen Fan, Haitao Zhang, Huipeng Liu, Xiaofei Pan, Su Yan, Hongliang Chen, Wei Guo, Lin Cai, Shuhua Wei
First page: 993
Abstract: This study employs an innovative dynamic switching test system to investigate the dynamic switching characteristics of three p-GaN HEMT devices. The dynamic switching characteristics are different from the previous research on the dynamic resistance characteristics of GaN devices, and the stability of GaN devices can be analyzed from the perspective of switching characteristics. Based on the theory of dynamic changes in threshold opening voltage and capacitance caused by electrical stress, the mechanism of dynamic switching characteristics of GaN HEMT devices is studied and analyzed in detail. The test results have shown that electrical stress induces trap ionization within the device, resulting in fluctuations in electric potential and ultimately leading to alterations in two critical factors of the dynamic switching characteristics of GaN HEMT devices, the parasitic capacitance and the threshold voltage. The dynamic changes in capacitance before and after electrical stress vary among devices, resulting in different dynamic switching characteristics. The test system is capable of extracting the switching waveform for visual comparison and quantitatively calculating the changes in switching parameters before and after electrical stressing. This test provides a prediction for the drift of switch parameters, offering pre-guidance for the robustness of the optimized application scheme.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080993
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 994: Study on Effect of Surface
Micro-Texture of Cemented Carbide on Tribological Properties of Bovine
Cortical Bone
Authors: Peng Shang, Bingfeng Liu, Chunhai Guo, Peijuan Cui, Zhanlin Hou, Fengbin Jin, Jianjun Zhang, Shijie Guo, Yuping Huang, Wenwu Zhang
First page: 994
Abstract: In bone-milling surgical procedures, the intense friction between the tool and bone material often results in high cutting temperatures, leading to the thermal necrosis of bone cells. This paper aims to investigate the effect of micro-texture on the tribological properties of YG8 cemented carbide in contact with bone. The main objective is to guide the design of tool surface microstructures to reduce frictional heat generation. To minimize experimental consumables and save time, numerical simulations are first conducted to determine the optimal machining depth for the texture. Subsequently, micro-textures with different shapes and pitches are prepared on the surface of YG8 cemented carbide. These textured samples are paired with bovine cortical bone pins featuring various bone unit arrangements, and friction and wear tests are conducted under physiological saline lubrication. The experimental results indicate that the appropriate shape and pitch of the micro-texture can minimize the coefficient of friction. The parallel arrangement of bone units exhibits a lower coefficient of friction compared to the vertical arrangement. This study holds significant implications for the design and fabrication of future micro-texture milling cutters.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080994
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 995: Editorial for the Special Issue on
Advances in Optoelectronic Devices, 2nd Edition
Authors: Feng Li, Zichuan Yi, Jiashuai Wang, Mouhua Jiang
First page: 995
Abstract: Optoelectronic devices have improved people’s quality of life and have received widespread attention for a long time [...]
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080995
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 996: Characteristic Study of a Typical
Satellite Solar Panel under Mechanical Vibrations
Authors: Xin Shen, Yipeng Wu, Quan Yuan, Junfeng He, Chunhua Zhou, Junfeng Shen
First page: 996
Abstract: As the most common energy source of spacecraft, photovoltaic (PV) power generation has become one of the hottest research fields. During the on-orbit operation of spacecraft, the influence of various uncertain factors and the unbalanced inertial force will make the solar PV wing vibrate and degrade its performance. In this study, we investigated the influence of mechanical vibration on the output characteristics of PV array systems. Specifically, we focused on a three-segment solar panel commonly found on satellites, analyzing both its dynamic response and electrical output characteristics under mechanical vibration using numerical simulation software. The correctness of the simulation model was partly confirmed by experiments. The results showed that the maximum output power of the selected solar panel was reduced by 5.53% and its fill factor exhibited a decline from the original value of 0.8031 to 0.7587, provided that the external load applied on the panel increased to 10 N/m2, i.e., the vibration frequency and the maximal deflection angle were 0.3754 Hz and 74.9871°, respectively. These findings highlight a significant decrease in the overall energy conversion efficiency of the solar panel when operating under vibration conditions.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080996
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 997: Enhanced CPU Design for SDN Controller
Authors: Hiba S. Bazzi, Ramzi A. Jaber, Ahmad M. El-Hajj, Fathelalem A. Hija, Ali M. Haidar
First page: 997
Abstract: Software-Defined Networking (SDN) revolutionizes network management by decoupling control plane functionality from data plane devices, enabling the centralized control and programmability of network behavior. This paper uses the ternary system to improve the Central Processing Unit (CPU) inside the SDN controller to enhance network management. The Multiple-Valued Logic (MVL) circuit shows remarkable improvement compared to the binary circuit regarding the chip area, propagation delay, and energy consumption. Moreover, the Carbon Nanotube Field-Effect Transistor (CNTFET) shows improvement compared to other transistor technologies regarding energy efficiency and circuit speed. To the best of our knowledge, this is the first time that a ternary design has been applied inside the CPU of an SDN controller. Earlier studies focused on Ternary Content-Addressable Memory (TCAM) in SDN. This paper proposes a new 1-trit Ternary Full Adder (TFA) to decrease the propagation delay and the Power–Delay Product (PDP). The proposed design is compared to the latest 17 designs, including 15 designs that are 1-trit TFA CNTFET-based, 2-bit binary FA FinFET-based, and 2-bit binary FA CMOS-based, using the HSPICE simulator, to optimize the CPU utilization in SDN environments, thereby enhancing programmability. The results show the success of the proposed design in reducing the propagation delays by over 99% compared to the 2-bit binary FA CMOS-based design, over 78% compared to the 2-bit binary FA FinFET-based design, over 91% compared to the worst-case TFA, and over 49% compared to the best-case TFAs.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080997
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 998: Implementation of Accurate Parameter
Identification for Proton Exchange Membrane Fuel Cells and Photovoltaic
Cells Based on Improved Honey Badger Algorithm
Authors: Wei-Lun Yu, Chen-Kai Wen, En-Jui Liu, Jen-Yuan Chang
First page: 998
Abstract: Predicting the system efficiency of green energy and developing forward-looking power technologies are key points to accelerating the global energy transition. This research focuses on optimizing the parameters of proton exchange membrane fuel cells (PEMFCs) and photovoltaic (PV) cells using the honey badger algorithm (HBA), a swarm intelligence algorithm, to accurately present the performance characteristics and efficiency of the systems. Although the HBA has a fast search speed, it was found that the algorithm’s search stability is relatively low. Therefore, this study also enhances the HBA’s global search capability through the rapid iterative characteristics of spiral search. This method will effectively expand the algorithm’s functional search range in a multidimensional and complex solution space. Additionally, the introduction of a sigmoid function will smoothen the algorithm’s exploration and exploitation mechanisms. To test the robustness of the proposed methodology, an extensive test was conducted using the CEC’17 benchmark functions set and real-life applications of PEMFC and PV cells. The results of the aforementioned test proved that with regard to the optimization of PEMFC and PV cell parameters, the improved HBA is significantly advantageous to the original in terms of both solving capability and speed. The results of this research study not only make definite progress in the field of bio-inspired computing but, more importantly, provide a rapid and accurate method for predicting the maximum power point for fuel cells and photovoltaic cells, offering a more efficient and intelligent solution for green energy.
Citation: Micromachines
PubDate: 2024-07-31
DOI: 10.3390/mi15080998
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 999: An Integrated Solution to FIB-Induced
Hydride Artifacts in Pure Zirconium
Authors: Yi Qiao, Zongwei Xu, Shilei Li, Fu Wang, Yubo Huang
First page: 999
Abstract: The preparation method of transmission electron microscopy (TEM) samples for pure zirconium was successfully executed using a focused ion beam (FIB) system. These samples unveiled artifact hydrides induced during the FIB sample preparation process, which resulted from stress damage, ion implantation, and ion irradiation. An innovative solution was proposed to effectively reduce the effect of artifact hydrides for FIB-prepared samples of hydrogen-sensitive materials, such as zirconium alloys. This development lays the groundwork for further research on the micro/nanostructures of zirconium alloys after ion irradiation, thereby facilitating the study of corrosion mechanisms and the prediction of service life for nuclear fuel cladding materials. Furthermore, the solution proposed in this study is also applicable to TEM sample preparation using FIB for other hydrogen-sensitive materials such as titanium, magnesium, and palladium.
Citation: Micromachines
PubDate: 2024-08-01
DOI: 10.3390/mi15080999
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1000: Effects of Group IVA Elements on the
Electrical Response of a Ge2Se3-Based Optically Gated Transistor
Authors: Md Faisal Kabir, Kristy A. Campbell
First page: 1000
Abstract: The optically gated transistor (OGT) has been previously demonstrated as a viable selector device for memristor devices, and may enable optical addressing within cross-point arrays. The OGT current–voltage response is similar to a MOSFET device, with light activating the gate instead of voltage. The OGT also provides a naturally built-in compliance current for a series resistive memory element, determined by the incident light intensity on the gate, thus keeping the integrated periphery circuitry size and complexity to a minimum for a memory array. The OGT gate comprises an amorphous Ge2Se3 material that can readily be doped with other elements to alter the transistor’s electrical properties. In this work, we explore the operation of the OGT when the Ge2Se3 gate material is doped with the Group IVA elements C, Si, Sn, and Pb. The dopant atoms provide changes to the optical and electrical properties that allow key electrical properties such as the dark current, photocurrent, switching speed, and threshold voltage to be tuned.
Citation: Micromachines
PubDate: 2024-08-01
DOI: 10.3390/mi15081000
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1001: Design and Fabrication of
High-Performance Piezoelectric Micromachined Ultrasonic Transducers Based
on Aluminum Nitride Thin Films
Authors: Le Zhang, Kunxian Yan, Lei Ye, Xiangyu Luo, Jian He, Xiujian Chou
First page: 1001
Abstract: Ultrasound is widely applied in diverse domains, such as medical imaging, non-destructive evaluation, and acoustic communication. Piezoelectric micromachined ultrasonic transducers (PMUTs) capable of generating and receiving ultrasonic signals at the micrometer level have become a prominent technology in the field of ultrasound. It is important to enrich the models of the PMUTs to meet the varied applications. In this study, a series of PMUT devices featured with various top electrode configurations, square, circular, and doughnut, were designed to assess the influence of shape on the emission efficacy. It was demonstrated that the PMUTs with a circular top electrode were outperformed, which was calculated from the external acoustic pressure produced by the PMUTs operating in the fundamental resonant mode at a specified distance. Furthermore, the superior performance of PMUT arrays were exhibited through computational simulations for the circular top electrode geometries. Conventional microelectromechanical systems (MEMS) techniques were used to fabricate an array of PMUTs based on aluminum nitride (AlN) films. These findings make great contributions for enhancing the signal transmission sensitivity and bandwidth of PMUTs, which have significant potential in non-destructive testing and medical imaging applications.
Citation: Micromachines
PubDate: 2024-08-01
DOI: 10.3390/mi15081001
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1002: Development of Precision Controllable
Magnetic Field-Assisted Platform for Micro Electrical Machining
Authors: Cheng Guo, Weizhen Zhuang, Jingwen He
First page: 1002
Abstract: In order to introduce the magnetic field into micro electrical machining technology to explore the influence of magnetic field on micro electrical machining, the development of a precision controllable magnetic field-assisted platform is particularly important. This platform needs to precisely control the spatial magnetic field. This study first completes the hardware design and construction of the magnetic field generation device, using electromagnetic coils with soft iron cores as the sources of the magnetic field. Mathematical models of the magnetic field are established and calibrated. Since the magnetic dipole model cannot effectively describe the magnetic field generated by the electromagnetic coil, this study adopts a more precise description method: the spherical harmonic function expansion model and the magnetic multipole superposition model. The calibration of the magnetic field model is based on actual excitation magnetic field data, so a magnetic field sampling device is designed to obtain the excitation magnetic field of the workspace. The model is calibrated based on a combination of the theoretical model and magnetic field data, and the performance of the constructed setup is analyzed. Finally, a magnetic field-assisted platform has been developed which can generate magnetic fields in any direction within the workspace with intensities ranging from 0 to 0.2 T. Its magnetic field model arrives at an error percentage of 2.986%, a variance of 0.9977, and a root mean square error (RMSE) of 0.71 mT, achieving precise control of the magnetic field in the workspace.
Citation: Micromachines
PubDate: 2024-08-01
DOI: 10.3390/mi15081002
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1003: Physics-Based Artificial Neural
Network Assisting in Extracting Transient Properties of Extrinsically
Triggering Photoconductive Semiconductor Switches
Authors: Zhong Zheng, Huiyong Hu, Yutian Wang, Tianlong Zhao, Qian Sun, Hui Guo
First page: 1003
Abstract: In this paper, a physics-based ANN assisting method for extracting transient properties of extrinsically triggering photoconductive semiconductor switches (ET-PCSSs) is proposed. It exploits the nonlinear mapping of ANN between transient current (input) and doping concentration (output). According to the basic laws of photoelectric device operating, two types of ANN models are constructed by gaussian and polynomial fitting. The mean absolute error (MAE) of forecasting transient photocurrent can be less than 10 A under low triggering optical powers, which verifies the feasibility of ANN assisting TCAD applied to PCSSs. The results are comparable to computation by Mixed-Mode simulation, yet even thousands of seconds of CPU runtime cost are saved in every period. To improve the robustness of the Poly-ANN predictor, Bayesian optimization (BO) is implemented for minimizing the curl deviation of photocurrent-time curves.
Citation: Micromachines
PubDate: 2024-08-01
DOI: 10.3390/mi15081003
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1004: Microfluidic Wound-Healing Assay for
Comparative Study on Fluid Dynamic, Chemical and Mechanical Wounding on
Microglia BV2 Migration
Authors: Ehsan Yazdanpanah Moghadam, Nahum Sonenberg, Muthukumaran Packirisamy
First page: 1004
Abstract: Microglial cells, or brain immune cells, are highly dynamic and continuously migrate in pathophysiological conditions. Their adhesion, as a physical characteristic, plays a key role in migration. In this study, we presented a microfluidic chip combination of two assays: a microglial BV2 adhesion assay and a wound-healing migration assay. The chip could create the cell-free area (wound) under chemical stimuli with trypsin (chemical assay) and also mechanical stimuli with the PBS flow (mechanical assay). The microfluidic chip functioned as the cell adhesion assay during wounding, when the cell adhesion of microglia BV2 cells was characterized by the cell removal time under various shear stress ranges. The cell detachment pattern on the glass substrate was found under physiological conditions. After wounding, the chip operated as a migration assay; it was shown that cell migration in the cell-free area generated chemically with trypsin was highly improved compared to mechanical cell-free area creations with PBS flow and the scratch assay. Our findings indicated that the increase in inlet flow rate in the mechanical assay led to a reduced experiment time and mechanical force on the cells, which could improve cell migration. Furthermore, the study on the effect of the device geometry showed that the increased channel width had an inhibitory effect on cell migration. The bi-functional chip offers an opportunity for the development of new models for a better understanding of cellular adhesion and migration in in vitro microenvironments.
Citation: Micromachines
PubDate: 2024-08-02
DOI: 10.3390/mi15081004
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1005: A CMOS-Compatible Process for ≥3 kV
GaN Power HEMTs on 6-inch Sapphire Using In Situ SiN as the Gate
Dielectric
Authors: Jie Zhang, Xiangdong Li, Jian Ji, Shuzhen You, Long Chen, Lezhi Wang, Zilan Li, Yue Hao, Jincheng Zhang
First page: 1005
Abstract: The application of GaN HEMTs on silicon substrates in high-voltage environments is significantly limited due to their complex buffer layer structure and the difficulty in controlling wafer warpage. In this work, we successfully fabricated GaN power HEMTs on 6-inch sapphire substrates using a CMOS-compatible process. A 1.5 µm thin GaN buffer layer with excellent uniformity and a 20 nm in situ SiN gate dielectric ensured uniformly distributed VTH and RON across the entire 6-inch wafer. The fabricated devices with an LGD of 30 µm and WG of 36 mm exhibited an RON of 18.06 Ω·mm and an off-state breakdown voltage of over 3 kV. The electrical mapping visualizes the high uniformity of RON and VTH distributed across the whole 6-inch wafer, which is of great significance in promoting the applications of GaN power HEMTs for medium-voltage power electronics in the future.
Citation: Micromachines
PubDate: 2024-08-02
DOI: 10.3390/mi15081005
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1006: Indirect Enhancement of ALD Thin-Film
Authors: Pi-Chen Lin, Jun-Yu Li, Hou-Jen Chen, Kaifan Lin, Miin-Jang Chen, Kun-Ming Lin, Hsin-Chih Lin
First page: 1006
Abstract: The purpose of this study is to investigate the indirect effects on the properties of ZrO2 films deposited by atomic layer deposition (ALD) when an Mg-Ca alloy is modified through equal-channel angular pressing (ECAP) following extrusion. The study aims to understand how the increase in CaO content in the native oxide layer of the Mg-Ca alloy influences the crystallinity and defect density of the ZrO2 film. Consequently, the corrosion protection performance of the ZrO2 film is enhanced by 1.2 to 1.5 times. A reduction in the anti-scratch property of the ZrO2 film was also observed, with a critical load reduction of 34 μN. This research provides a detailed analysis of the modifications induced by ECAP on the as-extruded Mg-Ca alloy and its subsequent impact on the properties of the ZrO2 film.
Citation: Micromachines
PubDate: 2024-08-03
DOI: 10.3390/mi15081006
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1007: Recent Advances in Photoacoustic
Imaging: Current Status and Future Perspectives
Authors: Huibin Liu, Xiangyu Teng, Shuxuan Yu, Wenguang Yang, Tiantian Kong, Tangying Liu
First page: 1007
Abstract: Photoacoustic imaging (PAI) is an emerging hybrid imaging modality that combines high-contrast optical imaging with high-spatial-resolution ultrasound imaging. PAI can provide a high spatial resolution and significant imaging depth by utilizing the distinctive spectroscopic characteristics of tissue, which gives it a wide variety of applications in biomedicine and preclinical research. In addition, it is non-ionizing and non-invasive, and photoacoustic (PA) signals are generated by a short-pulse laser under thermal expansion. In this study, we describe the basic principles of PAI, recent advances in research in human and animal tissues, and future perspectives.
Citation: Micromachines
PubDate: 2024-08-04
DOI: 10.3390/mi15081007
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1008: Temperature Characteristics Modeling
for GaN PA Based on PSO-ELM
Authors: Qian Lin, Meiqian Wang
First page: 1008
Abstract: In order to solve the performance prediction and design optimization of power amplifiers (PAs), the performance parameters of Gallium Nitride high-electron-mobility transistor (GaN HEMT) PAs at different temperatures are modeled based on the particle swarm optimization–extreme learning machine (PSO-ELM) and extreme learning machine (ELM) in this paper. Then, it can be seen that the prediction accuracy of the PSO-ELM model is superior to that of ELM with a minimum mean square error (MSE) of 0.0006, which indicates the PSO-ELM model has a stronger generalization ability when dealing with the nonlinear relationship between temperature and PA performance. Therefore, this investigation can provide vital theoretical support for the performance optimization of PA design.
Citation: Micromachines
PubDate: 2024-08-05
DOI: 10.3390/mi15081008
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1009: Two CMOS Wilkinson Power Dividers
Using High Slow-Wave and Low-Loss Transmission Lines
Authors: Chatrpol Pakasiri, Wei-Sen Teng, Sen Wang
First page: 1009
Abstract: This work presents two Wilkinson power dividers (WPDs) using multi-layer pseudo coplanar waveguide (PCPW) structures. The PCPW-based WPDs were designed, implemented, and verified in a standard 180 nm CMOS process. The proposed PCPW features high slow-wave and low-loss performances compared to other common transmission lines. The two WPDs are based on the same PCPW structure parameters in terms of line width, spacing, and used metal layers. One WPD was realized in a straight PCPW-based layout, and the other WPD was realized in a meandered PCPW-based layout. Both the two WPDs worked up to V-band frequencies, as expected, which also demonstrates that the PCPW guiding structure is less susceptible to the effects of meanderings on the propagation constant and characteristic impedance. The meandered design shows that the measured insertion losses were about 5.1 dB, and its return losses were better than 17.5 dB at 60 GHz. In addition, its isolation, amplitude imbalance, and phase imbalance were 18.5 dB, 0.03 dB, and 0.4°, respectively. The core area was merely 0.2 mm × 0.23 mm, or 1.8 × 10−3λo2.
Citation: Micromachines
PubDate: 2024-08-05
DOI: 10.3390/mi15081009
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1010: Replication of Radial Pulses Using
Magneto-Rheological Fluids
Authors: Miranda Eaton, Jeong-Hoi Koo, Tae-Heon Yang, Young-Min Kim
First page: 1010
Abstract: The radial pulse is a critical health marker with expanding applications in wearable technology. To improve these applications, developing a pulse generator that consistently produces realistic pulses is crucial for validation and training. The goal of this study was to design and test a cost-effective pulse simulator that can accurately replicate a wide range of age-dependent radial pulses with simplicity and precision. To this end, this study incorporated a magneto-rheological (MR) fluid device into a cam-based pulse simulator. The MR device, as a key component, enables pulse shaping without the need for additional cams, substantially reducing the cost and complexity of control compared with existing pulse simulators. To evaluate the performance of the MR pulse simulator, the root-mean-square (RMS) error criterion (less than 5%) was used to compare the experimentally obtained pulse waveform with the in vivo pulse waveform for specific age groups. After demonstrating that the MR simulator could produce three representative in vivo pulses, a parametric study was conducted to show the feasibility of the slope-based pulse-shaping method for the MR pulse simulator to continuously generate a range of age-related pulses.
Citation: Micromachines
PubDate: 2024-08-06
DOI: 10.3390/mi15081010
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1011: Micro-Opto-Electro-Mechanical Systems
for High-Precision Displacement Sensing: A Review
Authors: Chenguang Xin, Yingkun Xu, Zhongyao Zhang, Mengwei Li
First page: 1011
Abstract: High-precision displacement sensing has been widely used across both scientific research and industrial applications. The recent interests in developing micro-opto-electro-mechanical systems (MOEMS) have given rise to an excellent platform for miniaturized displacement sensors. Advancement in this field during past years is now yielding integrated high-precision sensors which show great potential in applications ranging from photoacoustic spectroscopy to high-precision positioning and automation. In this review, we briefly summarize different techniques for high-precision displacement sensing based on MOEMS and discuss the challenges for future improvement.
Citation: Micromachines
PubDate: 2024-08-06
DOI: 10.3390/mi15081011
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1012: Application of a Modified First-Order
Plate Theory to Structural Analysis of Sensitive Elements in a
Pyroelectric Detector
Authors: Mengmeng Lian, Cuiying Fan, Xiaohan Zhan, Minghao Zhao, Guoshuai Qin, Chunsheng Lu
First page: 1012
Abstract: Pyroelectric materials, with piezoelectricity and pyroelectricity, have been widely used in infrared thermal detectors. In this paper, a modified first-order plate theory is extended to analyze a pyroelectric sensitive element structure. The displacement, temperature, and electric potential expand along the thickness direction. The governing equation of the pyroelectric plate is built up. The potential distributions with upper and lower electrodes are obtained under different supported boundary conditions. The corresponding numerical results of electric potential are consistent with those obtained by the three-dimensional finite element method. Meanwhile, the theoretical results of electric potential are close to that of experiments. The influence of supported boundary conditions, piezoelectric effect, and plate thickness are analyzed. Numerical results show that the piezoelectric effect reduces the electric potential. The thickness of the pyroelectric plate enhances the electric potential but reduces the response speed of the detector. It is anticipated that the pyroelectric plate theory can provide a theoretical approach for the structural design of pyroelectric sensitive elements.
Citation: Micromachines
PubDate: 2024-08-06
DOI: 10.3390/mi15081012
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1013: Modeling and Experimental Study of
Vibration Energy Harvester with Triple-Frequency-Up Voltage Output by
Vibration Mode Switching
Authors: Jiawen Xu, Zhikang Liu, Wenxing Dai, Ru Zhang, Jianjun Ge
First page: 1013
Abstract: Conventional wireless sensors rely on chemical batteries. Replacing or charging their batteries is tedious and costly in some situations. As usable kinetic energy exists in the environment, harvesting vibration energy and converting it into electrical energy has become a hotspot. However, the power output capability of a conventional piezoelectric energy harvester (PEH) is limited by its low operational frequency. This paper presents a new mechanism for achieving continuous triple-frequency-up voltage output in a PEH. The proposed system consists of a slender piezoelectric cantilever with two short cantilever-based stoppers. The piezoelectric cantilever undergoes a pure bending mode without contacting the stoppers. In addition, the beam switches into a new vibration mode by contacting the stoppers. The vibration modes switching yields reverses the signs of voltage outputs, inducing triple-frequency-up voltage output. Analytical and experimental investigations are presented, and it is shown that a significant triple-frequency up-conversion of the voltage output can be obtained over a wide frequency range. A peak power output of 3.03 mW was obtained. The proposed energy harvester can support a wireless sensor node.
Citation: Micromachines
PubDate: 2024-08-06
DOI: 10.3390/mi15081013
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1014: The Design of a Multifunctional Coding
Transmitarray with Independent Manipulation of the Polarization States
Authors: Shunlan Zhang, Weiping Cao, Tiesheng Wu, Jiao Wang, Ying Wei
First page: 1014
Abstract: Manipulating orthogonally polarized waves independently in a single metasurface is pivotal. However, independently controlling the phase shifts of orthogonally polarized waves is difficult, especially in the same frequency bands. Here, we propose a receiver-phase shift-transmitter transmitarray with independent control of arbitrary polarization states in the same frequency bands, in which transmission rates reach more than 90% in the frequency bands 4.2~4.9 GHz and 5.3~5.5 GHz. By introducing a phase-regulation structure to each element, phases covering 360° for different polarized incident waves can be independently controlled by different geometric parameters, and two-bit coding phases can be obtained. The design principle based on the two-port network’s scattering matrix has been analyzed. To verify the independent tuning abilities of the proposed transmitarray for different polarization incidences in the same frequency bands, a multifunctional receive-phase shift-radiation coding transmitarray (RPRCT), which is composed of 16×16 elements, with functions of anomalous refraction (for example, orbital angular momentum wave) and focusing transmission for different polarized incident waves was simulated and measured. The measured results agree reasonably well with the simulated ones. Our findings provide a simple method for obtaining a multifunctional metasurface with orthogonal polarization in the same frequency bands, which greatly improves the capacity and spectral efficiency of communication channels.
Citation: Micromachines
PubDate: 2024-08-07
DOI: 10.3390/mi15081014
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1015: Series/Parallel Switching for
Increasing Power Extraction from Thermoelectric Power Generators
Authors: Shingo Terashima, Ryuji Sorimachi, Eiji Iwase
First page: 1015
Abstract: We propose a method for increasing power extraction from a thermoelectric generator (TEG) by switching between series/parallel circuit configurations of thermoelectric elements, which can adjust the internal impedance of the TEG. The power characteristics of the TEG can be adjusted to the load characteristics of the connected device and the relevant ambient temperature. In this paper, we analyzed the change in the TEG characteristics with the series/parallel switching function. We evaluated the power supply to the connected devices at different ambient temperatures and different series/parallel configurations and confirmed that the extracted power could be increased. By theoretically analyzing the circuit configuration of the thermoelectric devices, the switching required to improve the power extraction, and the temperature difference at which switching occurred, we devised a design method for a TEG with circuit switching in order to increase power extraction with any device. We demonstrated the configuration of switching by using a system in which a TEG supplied power to an external wireless transmitter circuit. In this system, the optimal configuration differed at temperature differences of 3.0 K and 4.0 K. At a temperature difference of 3.0 K, the 2-series/1-parallel configuration provided 10% more power to the external circuit than the 1-series/2-parallel configuration. On the other hand, at the temperature difference of 4.0 K, the 1-series/2-parallel configuration provided 23% more power than the 2-series/1-parallel configuration.
Citation: Micromachines
PubDate: 2024-08-07
DOI: 10.3390/mi15081015
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1016: Development of a Plate Linear
Ultrasonic Motor Using the Power Flow Method
Authors: Yue Jian, Zhen Liu, Junfeng He, Wenjie Zhou, Huazhuo Liang
First page: 1016
Abstract: Linear ultrasonic motors can output large thrust stably in a narrow space. In this paper, a plate linear ultrasonic motor is studied. Firstly, the configuration and operating principle of the Π-type linear ultrasonic motor is illustrated. Then, two slotting schemes are put forward for the stator to enlarge the amplitude of the driving foot and improve the output performance of motor. After that, a novel optimization method based on the power flow method is suggested to describe the energy flow of stator, so as to estimate the slotting schemes. Finally, the prototypes are manufactured and tested. The experimental results show that the output performance of both new motors are excellent. The maximum output thrust of the arc slotted motor is 76 N/94 N, and the corresponding maximum no-load speed is 283 mm/s/213 mm/s, while the maximum output thrust of V-slotted motor reaches 90 N/120 N, and the maximum no-load speed reaches 223 mm/s/368 mm/s.
Citation: Micromachines
PubDate: 2024-08-08
DOI: 10.3390/mi15081016
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1017: A Large-Scan-Range Electrothermal
Micromirror Integrated with Thermal Convection-Based Position Sensors
Authors: Anrun Ren, Yingtao Ding, Hengzhang Yang, Teng Pan, Ziyue Zhang, Huikai Xie
First page: 1017
Abstract: This paper presents the design, simulation, fabrication, and characterization of a novel large-scan-range electrothermal micromirror integrated with a pair of position sensors. Note that the micromirror and the sensors can be manufactured within a single MEMS process flow. Thanks to the precise control of the fabrication of the grid-based large-size Al/SiO2 bimorph actuators, the maximum piston displacement and optical scan angle of the micromirror reach 370 μm and 36° at only 6 Vdc, respectively. Furthermore, the working principle of the sensors is deeply investigated, where the motion of the micromirror is reflected by monitoring the temperature variation-induced resistance change of the thermistors on the substrate during the synchronous movement of the mirror plate and the heaters. The results show that the full-range motion of the micromirror can be recognized by the sensors with sensitivities of 0.3 mV/μm in the piston displacement sensing and 2.1 mV/° in the tip-tilt sensing, respectively. The demonstrated large-scan-range micromirror that can be monitored by position sensors has a promising prospect for the MEMS Fourier transform spectrometers (FTS) systems.
Citation: Micromachines
PubDate: 2024-08-08
DOI: 10.3390/mi15081017
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1018: Investigation of Piezoelectric
Properties in Ca-Doped PbBa(Zr,Ti)O3 (PBZT) Ceramics
Authors: Jolanta Makowska, Marian Pawełczyk, Andrzej Soszyński, Tomasz Pikula, Małgorzata Adamczyk-Habrajska
First page: 1018
Abstract: The perovskite-structured materials Pb0.75Ba0.251−xCax(Zr0.7Ti0.3)O3 for x = 1 and 2 at.% were synthesized using the conventional mixed-oxide method and carbonates. Microstructural analysis, performed using a scanning electron microscope, revealed rounded grains with relatively inhomogeneous sizes and distinct grain boundaries. X-ray diffraction confirmed that the materials exhibit a rhombohedral structure with an R3c space group at room temperature. Piezoelectric resonance measurements were conducted to determine the piezoelectric and elastic properties of the samples. The results indicated that a small amount of calcium doping significantly enhanced the piezoelectric coefficient d31. The calcium-doped ceramics exhibited higher electrical permittivity across the entire temperature range compared to the pure material, as well as a significant value of remanent polarization. These findings indicate that the performance parameters of the base material have been significantly improved, making these ceramics promising candidates for various applications.
Citation: Micromachines
PubDate: 2024-08-09
DOI: 10.3390/mi15081018
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1019: A 640 nA IQ Output-Capacitor-Less Low
Dropout (LDO) Regulator with Sub-Threshold Slew-Rate Enhancement for
Narrow Band Internet of Things (NB-IoT) Applications
Authors: Yuxin Zhang, Jueping Cai, Jizhang Chen, Yixin Yin
First page: 1019
Abstract: An ultra-low quiescent current output-capacitor-less low dropout (OCL-LDO) regulator for power-sensitive applications is proposed in this paper. To improve the gain of the OCL-LDO feedback loop, the error amplifier employs a combination of a cross-coupled input stage for boosting the equivalent input transconductance and a negative resistance technique to improve the gain. Meanwhile, in order to address the issue of transient response of the ultra-low quiescent current OCL-LDO, a sub-threshold slew-rate enhancement circuit is proposed in this paper, which consists of a transient signal input stage and a slew-rate current increase branch. The proposed OCL-LDO is fabricated in a 0.18 μm CMOS process with an effective area of 0.049 mm2. According to the measurement results, the proposed OCL-LDO has a maximum load current of 100 mA and a minimum quiescent current of 640 nA at an input voltage of 1.2 V and an output voltage of 1 V. The overshoot and undershoot voltages are 197 mV and 201 mV, respectively, and the PSR of the OCL-LDO is −72.4 dB at 1 kHz when the load current is 100 μA. In addition, the OCL-LDO has a load regulation of 7.6 μV/mA and a line regulation of 0.87 mV/V.
Citation: Micromachines
PubDate: 2024-08-09
DOI: 10.3390/mi15081019
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1020: Simulation and Experimental Study on
Stress Relaxation Response of Polycrystalline γ-TiAl Alloy under
Nanoindentation Based on Molecular Dynamics
Authors: Junye Li, Chunyu Wang, Jianhe Liu, Xiwei Dong, Jinghe Zhao, Ying Chen
First page: 1020
Abstract: This study employed nano-indentation technology, molecular dynamics simulation, and experimental investigation to examine the stress relaxation behaviour of a polycrystalline γ-TiAl alloy. The simulation enabled the generation of a load-time curve, the visualisation of internal defect evolution, and the mapping of stress distribution across each grain during the stress relaxation stage. The findings indicate that the load remains stable following an initial decline, thereby elucidating the underlying mechanism of load change during stress relaxation. Furthermore, a nano-indentation test was conducted on the alloy, providing insight into the load variation and stress relaxation behaviour under different loading conditions. By comparing the simulation and experimental results, this study aims to guide the theoretical research and practical application of γ-TiAl alloys.
Citation: Micromachines
PubDate: 2024-08-09
DOI: 10.3390/mi15081020
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1021: Comprehensive Review on Research
Status and Progress in Precision Grinding and Machining of BK7 Glasses
Authors: Dayong Yang, Zhiyang Zhang, Furui Wei, Shuping Li, Min Liu, Yuwei Lu
First page: 1021
Abstract: BK7 glass, with its outstanding mechanical strength and optical performance, plays a crucial role in many cutting-edge technological fields and has become an indispensable and important material. These fields have extremely high requirements for the surface quality of BK7 glass, and any small defects or losses may affect its optical performance and stability. However, as a hard and brittle material, the processing of BK7 glass is extremely challenging, requiring precise control of machining parameters to avoid material fracture or excessive defects. Therefore, how to obtain the required surface quality with lower cost machining techniques has always been the focus of researchers. This article introduces the properties, application background, machining methods, material removal mechanism, and surface and subsurface damage of optical glass BK7 material. Finally, scientific predictions and prospects are made for future development trends and directions for improvement of BK7 glass machining.
Citation: Micromachines
PubDate: 2024-08-09
DOI: 10.3390/mi15081021
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1022: A Wideband Millimeter-Wave Dual-Beam
Dielectric Resonator Antenna with Substrate Integration Capability
Authors: Jin Shi, Ranhao Xu, Bowen Wu, Lei Wang, Ruirui Jiang
First page: 1022
Abstract: A wideband dual-beam dielectric resonator antenna (DRA) with substrate integration capability was proposed for millimeter-wave (mm-wave) applications. The four rows of air vias along the x-direction and two extended rectangular patches could shift the undesirable radiation mode upward and move the conical-beam radiation mode downward, respectively. Thus, the TE211 mode and the TE411 mode of the patch-loaded perforated rectangular substrate integrated dielectric resonator (SIDR) supporting the dual-beam radiation can be retained in the operating band, and their radiation can be improved by the air vias along the y-direction. The T-shaped line coupled dual-slot structure could excite the above two modes, and a dual-slot mode supporting dual-beam radiation could also work. Then, a wideband DRA with a stable dual-beam radiation angle can be achieved, and its impedance matching can be improved by two air slots on two sides. Compared with the state-of-the-art dual-beam antennas, the proposed antenna shows a wider bandwidth, a higher radiation efficiency, and the substrate integration capability of DRA, making it more suitable for mm-wave applications. For demonstration, a 1 × 4 array was designed with the 10 dB impedance matching bandwidth of 41.2% and the directions of the dual beams between ±30° and ±35°.
Citation: Micromachines
PubDate: 2024-08-10
DOI: 10.3390/mi15081022
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1023: Research on Polarization Modulation of
Electro-Optical Crystals for 3D Imaging Reconstruction
Authors: Houpeng Sun, Yingchun Li, Huichao Guo, Chenglong Luan, Laixian Zhang, Haijing Zheng, Youchen Fan
First page: 1023
Abstract: A method for enhancing the resolution of 3D imaging reconstruction by employing the polarization modulation of electro-optical crystals is proposed. This technique utilizes two polarizers oriented perpendicular to each other along with an electro-optical modulation crystal to achieve high repetition frequency and narrow pulse width gating. By varying the modulation time series of the electro-optical crystal, three-dimensional gray images of the laser at different distances are acquired, and the three-dimensional information of the target is reconstructed using the range energy recovery algorithm. This 3D imaging system can be implemented with large area detectors, independent of the an Intensified Charge-Coupled Device (ICCD) manufacturing process, resulting in improved lateral resolution. Experimental results demonstrate that when imaging a target at the distance of 20 m, the lateral resolution within the region of interest is 2560 × 2160, with a root mean square error of 3.2 cm.
Citation: Micromachines
PubDate: 2024-08-11
DOI: 10.3390/mi15081023
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1024: Hybrid Fibers with Subwavelength-Scale
Liquid Core for Highly Sensitive Sensing and Enhanced Nonlinearity
Authors: Caoyuan Wang, Ruowei Yu, Yucheng Ye, Cong Xiong, Muhammad Hanif Ahmed Khan Khushik, Limin Xiao
First page: 1024
Abstract: Interest grows in designing silicon-on-insulator slot waveguides to trap optical fields in subwavelength-scale slots and developing their optofluidic devices. However, it is worth noting that the inherent limitations of the waveguide structures may result in high optical losses and short optical paths, which challenge the device’s performance in optofluidics. Incorporating the planar silicon-based slot waveguide concept into a silica-based hollow-core fiber can provide a perfect solution to realize an efficient optofluidic waveguide. Here, we propose a subwavelength-scale liquid-core hybrid fiber (LCHF), where the core is filled with carbon disulfide and surrounded by a silicon ring in a silica background. The waveguide properties and the Stimulated Raman Scattering (SRS) effect in the LCHF are investigated. The fraction of power inside the core of 56.3% allows for improved sensitivity in optical sensing, while the modal Raman gain of 23.60 m−1·W−1 is two times larger than that generated around a nanofiber with the interaction between the evanescent optical field and the surrounding Raman media benzene-methanol, which enables a significant low-threshold SRS effect. Moreover, this in-fiber structure features compactness, robustness, flexibility, ease of implementation in both trace sample consumption and reasonable liquid filling duration, as well as compatibility with optical fiber systems. The detailed analyses of the properties and utilizations of the LCHF suggest a promising in-fiber optofluidic platform, which provides a novel insight into optofluidic devices, optical sensing, nonlinear optics, etc.
Citation: Micromachines
PubDate: 2024-08-11
DOI: 10.3390/mi15081024
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1025: Fragmentation Characteristics of
Bubbles in a Throttling Hole Pipe
Authors: Yufeng Zhang, Zhijie Huang, Lixia Sun
First page: 1025
Abstract: To enhance the performance of tubular microbubble generators, the Volume of Fluid (VOF) multiphase flow model in COMSOL Multiphysics was used to simulate the bubble fragmentation characteristics within a throttling hole microbubble generator. The effects of the inlet speed of the throttling hole pipe, the diameter of the throttling hole, and the length of the expansion section on bubble fragmentation performance were analyzed. The results indicated that an increase in the inlet speed of the throttling hole pipe gradually improved the bubble fragmentation performance. However, an increase in the throttling hole diameter significantly reduced the bubble fragmentation performance. Changes in the length of the expansion section had a minor impact on the bubble fragmentation performance. Experimental methods were used to verify the characteristics of bubble fragmentation, and it was found that the simulation and experimental results were consistent. This provides a theoretical basis and practical guidance for the design optimization of tubular microbubble generators.
Citation: Micromachines
PubDate: 2024-08-11
DOI: 10.3390/mi15081025
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1026: Degradation Induced by Total Ionizing
Dose and Hot Carrier Injection in SOI FinFET Devices
Authors: Hao Yu, Wei Zhou, Hongxia Liu, Shulong Wang, Shupeng Chen, Chang Liu
First page: 1026
Abstract: The working environment of electronic devices in the aerospace field is harsh. In order to ensure the reliable application of the SOI FinFET, the total ionizing dose (TID) and hot carrier injecting (HCI) reliability of an SOI FinFET were investigated in this study. First, the influence of TID on the device was simulated. The results show that TID causes the threshold voltage to decrease and the off-state current and subthreshold swing to increase. TID causes more damage to the device at high temperature and also reduces the saturation drain current of the device. HCI causes the device threshold voltage to increase and the saturation drain current to decrease. The HCI is more severe at high temperatures. Finally, the coupling effects of the two were simulated, and the results show that the two effects cancel each other out, and the degradation of various electrical characteristic parameters is different under different coupling modes.
Citation: Micromachines
PubDate: 2024-08-11
DOI: 10.3390/mi15081026
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1027: Advanced Neural Functional Imaging in
C. elegans Using Lab-on-a-Chip Technology
Authors: Youngeun Kwon, Jihye Kim, Ye Bin Son, Sol Ah Lee, Shin Sik Choi, Yongmin Cho
First page: 1027
Abstract: The ability to perceive and adapt to environmental changes is crucial for the survival of all organisms. Neural functional imaging, particularly in model organisms, such as Caenorhabditis elegans, provides valuable insights into how animals sense and process external cues through their nervous systems. Because of its fully mapped neural anatomy, transparent body, and genetic tractability, C. elegans serves as an ideal model for these studies. This review focuses on advanced methods for neural functional imaging in C. elegans, highlighting calcium imaging techniques, lab-on-a-chip technologies, and their applications in the study of various sensory modalities, including chemosensation, mechanosensation, thermosensation, photosensation, and magnetosensation. We discuss the benefits of these methods in terms of precision, reproducibility, and ability to study dynamic neural processes in real time, ultimately advancing our understanding of the fundamental principles of neural activity and connectivity.
Citation: Micromachines
PubDate: 2024-08-12
DOI: 10.3390/mi15081027
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1028: High-Resolution Rotation-Measuring
System for MEMS Ultrasonic Motors Using Tunneling Magnetoresistance
Sensors
Authors: Jiangbo He, Qiuyue Feng, Yu Chen, Tianyu Yang, Xiaoshi Li, Wu Zhou
First page: 1028
Abstract: This study proposes a high-resolution rotation-measuring system for miniaturized MEMS ultrasonic motors using tunneling magnetoresistance (TMR) sensors for the first time. Initially, the architecture and principle of the rotation-measuring system are described in detail. Then, the finite element simulation is implemented to determine the miniaturized permanent magnet’s residual magnetization, dimensions, and TMR sensor position. Finally, the experiments are implemented to evaluate the performance. Using calibration based on a high-precision servo motor, it is found that the relationship between the output and rotational angle is highly linear and immune to the rotor’s out-of-plane movement. Meanwhile, the angle-detecting resolution is higher than 0.1°. After the calibration, the continuous rotation of the MEMS ultrasonic motor is tested. It is found that the angle testing result varies with a period close to 360°, which indicates that the rotation-measuring system has successfully detected the motor’s rotation.
Citation: Micromachines
PubDate: 2024-08-12
DOI: 10.3390/mi15081028
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1029: Ultrathin Small Outline Package Key
Techniques for High-Speed Chips with Multi-Leads
Authors: Lijun Zhang, Wenqiang Dang, Yongshun Wang, Jinbing Zhang
First page: 1029
Abstract: The key technologies for the ultrathin small outline package (TSOP) of large-sized high-speed chips have been designed and developed in this paper. The designing techniques, such as a 25 µm precise positioning dice attaching technique, a lead frame unit structure without a base island, and a lead co-plane layout inside the frame, were developed. The TSO package outline with a large number of leads, a frame unit arrangement, and a frame distribution with a base island and without one were improved. The technological problems, including the reduction in thickness, wafer cutting, chip sticking bonding, and plastic sealing, were successfully solved. The designed large-sized package products have many advantages, such as high availability, low cost, high reliability, and a short production cycle. This package technique can be widely used in various intellectual application regions.
Citation: Micromachines
PubDate: 2024-08-13
DOI: 10.3390/mi15081029
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1030: Recent Developments in Mechanical
Ultraprecision Machining for Nano/Micro Device Manufacturing
Authors: Tirimisiyu Olaniyan, Nadimul Faisal, James Njuguna
First page: 1030
Abstract: The production of many components used in MEMS or NEMS devices, especially those with com-plex shapes, requires machining as the best option among manufacturing techniques. Ultraprecision machining is normally employed to achieve the required shapes, dimensional accuracy, or improved surface quality in most of these devices and other areas of application. Compared to conventional machining, ultraprecision machining involves complex phenomenal processes that require extensive investigations for a better understanding of the material removal mechanism. Materials such as semiconductors, composites, steels, ceramics, and polymers are commonly used, particularly in devices designed for harsh environments or applications where alloyed metals may not be suitable. However, unlike alloyed metals, materials like semiconductors (e.g., silicon), ceramics (e.g., silicon carbide), and polymers, which are typically brittle and/or hard, present significant challenges. These challenges include achieving precise surface integrity without post-processing, managing the ductile-brittle transition, and addressing low material removal rates, among others. This review paper examines current research trends in mechanical ultraprecision machining and sustainable ultraprecision machining, along with the adoption of molecular dynamics simulation at the micro and nano scales. The identified challenges are discussed, and potential solutions for addressing these challenges are proposed.
Citation: Micromachines
PubDate: 2024-08-14
DOI: 10.3390/mi15081030
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1031: Fabrication of Porous Collagen
Scaffolds Containing Embedded Channels with Collagen Membrane Linings
Authors: Neda Fakhri, Arezoo Khalili, Terry Sachlos, Pouya Rezai
First page: 1031
Abstract: Tissues and organs contain an extracellular matrix (ECM). In the case of blood vessels, endothelium cells are anchored to a specialized basement membrane (BM) embedded inside the interstitial matrix (IM). We introduce a multi-structural collagen-based scaffold with embedded microchannels that mimics in vivo structures within vessels. Our scaffold consists of two parts, each containing two collagen layers, i.e., a 3D porous collagen layer analogous to IM lined with a thin 2D collagen film resembling the BM. Enclosed microchannels were fabricated using contact microprinting. Microchannel test structures with different sizes ranging from 300 to 800 µm were examined for their fabrication reproducibility. The heights and perimeters of the fabricated microchannels were ~20% less than their corresponding values in the replication PDMS mold; however, microchannel widths were significantly closer to their replica dimensions. The stiffness, permeability, and pore size properties of the 2D and 3D collagen layers were measured. The permeability of the 2D collagen film was negligible, making it suitable for mimicking the BM of large blood vessels. A leakage test at various volumetric flow rates applied to the microchannels showed no discharge, thereby verifying the reliability of the proposed integrated 2D/3D collagen parts and the contact printing method used for bonding them in the scaffold. In the future, multi-cell culturing will be performed within the 3D porous collagen and against the 2D membrane inside the microchannel, hence preparing this scaffold for studying a variety of blood vessel–tissue interfaces. Also, thicker collagen scaffold tissues will be fabricated by stacking several layers of the proposed scaffold.
Citation: Micromachines
PubDate: 2024-08-14
DOI: 10.3390/mi15081031
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1032: Optimal Motion Control of a Capsule
Endoscope in the Stomach Utilizing a Magnetic Navigation System with Dual
Permanent Magnets
Authors: Suhong Bae, Junhyoung Kwon, Jongyul Kim, Gunhee Jang
First page: 1032
Abstract: We propose a method to control the motion of a capsule endoscope (CE) in the stomach utilizing either a single external permanent magnet (EPM) or dual EPMs to extend the examination of the upper gastrointestinal tract. When utilizing the conventional magnetic navigational system (MNS) with a single EPM to generate tilting and rotational motions of the CE, undesired translational motion of the CE may prevent accurate examination. We analyzed the motion of the CE by calculating the magnetic torque and magnetic force applied to the CE using the point-dipole approximation model. Using the proposed model, we propose a method to determine the optimal position and orientation of the EPM to generate tilting and rotational motions without undesired translational motion of the CE. Furthermore, we optimized the weight of dual EPMs to develop a lightweight MNS. We prototyped the proposed MNS and experimentally verified that the developed MNS can generate tilting and rotational motions of the CE without any translational motion.
Citation: Micromachines
PubDate: 2024-08-14
DOI: 10.3390/mi15081032
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1033: Optimization of Hot Embossing
Condition Using Taguchi Method and Evaluation of Microchannels for
Flexible On-Chip Proton-Exchange Membrane Fuel Cell
Authors: Yubo Huang, Han Gao, Zhiheng Wu, Hongyang Xiao, Cao Xia, Yuanlin Xia, Zhuqing Wang
First page: 1033
Abstract: Hot embossing is a manufacturing technique used to create microchannels on polymer substrates. In recent years, microchannel fabrication technology based on hot embossing has attracted considerable attention due to its convenience and low cost. A new evaluation method of microchannels, as well as an approach to obtaining optimal hot embossing conditions based on the Taguchi method, is proposed in this paper to fabricate precise microchannels for a flexible proton-exchange membrane fuel cell (PEMFC). Our self-made hot embossing system can be used to fabricate assorted types of micro-channel structures on polymer substrates according to various applications, whose bottom width, top width, height and cross-sectional area vary in the aims of different situations. In order to obtain a high effective filling ratio, a new evaluation method is presented based on the four parameters of channel structures, and the Taguchi method is utilized to arrange three main factors (temperature, force and time) affecting the hot embossing in orthogonal arrays, quickly finding the optimal condition for the embossing process. The evaluation method for microchannels proposed in this paper, compared to traditional evaluation methods, incorporates the area factor, providing a more comprehensive assessment of the fabrication completeness of the microchannels. Additionally, it allows for the quick and simple identification of optimal conditions. The experimental results indicate that after determining the optimal embossing temperature, pressure and time using the Taguchi method, the effective filling rate remains above 95%, thereby enhancing the power density. Through variance analysis, it was found that temperature is the most significant factor affecting the hot embossing of microchannels. The high filling rate makes the process suitable for PEMFCs. The results demonstrate that under optimized process conditions, a self-made hot embossing system can effectively fabricate columnar structure microchannels for PEMFCs.
Citation: Micromachines
PubDate: 2024-08-14
DOI: 10.3390/mi15081033
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1034: A Droplet-Based Microfluidic Platform
for High-Throughput Culturing of Yeast Cells in Various Conditions
Authors: Min-Chieh Yu, Yung-Shin Sun
First page: 1034
Abstract: Yeast plays a significant role in a variety of fields. In particular, it is extensively used as a model organism in genetics and cellular biology studies, and is employed in the production of vaccines, pharmaceuticals, and biofuels. Traditional “bulk”-based studies on yeast growth often overlook cellular variability, emphasizing the need for single-cell analysis. Micro-droplets, tiny liquid droplets with high surface-area-to-volume ratios, offer a promising platform for investigating single or a small number of cells, allowing precise control and monitoring of individual cell behaviors. Microfluidic devices, which facilitate the generation of micro-droplets, are advantageous due to their reduced volume requirements and ability to mimic in vivo micro-environments. This study introduces a custom-designed microfluidic device to encapsulate yeasts in micro-droplets under various conditions in a parallel manner. The results reveal that optimal glucose concentrations promoted yeast growth while cycloheximide and Cu2+ ions inhibited it. This platform enhances yeast cultivation strategies and holds potential for high-throughput single-cell investigations in more complex organisms.
Citation: Micromachines
PubDate: 2024-08-15
DOI: 10.3390/mi15081034
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1035: Study on the Performance of Deep Red
to Near-Infrared pc-LEDs by the Simulation Method Considering the
Distribution of Phosphor Particles
Authors: Chenghang Li, Zikeng Fang, Ying Yan, Henan Li, Xiang Luo, Xuyue Wang, Ping Zhou
First page: 1035
Abstract: Effectively utilizing deep red to near-infrared (DR-NIR) phosphors to achieve the optimal performance of NIR phosphor-converted white LEDs (DR-NIR pc-wLEDs) is currently a research hotspot. In this study, an optical model of DR-NIR pc-wLEDs with virtual multilayer fluorescent films was established based on the Monte Carlo ray-tracing method. Different gradient distributions of the particles were assigned within the fluorescent film to explore their impact on the optical performance of pc-LEDs. The results show that, for the case with single-type particles, distributing more DR-NIR particles far from the blue LED chip increased the overall radiant power. The distribution of more DR-NIR particles near the chip increased the conversion ratio from blue to DR-NIR light. The ratio of the 707 nm fluorescence emission intensity to the 450 nm excitation light intensity increased from 1:0.51 to 1:0.28. For multiple-type particles, changes in the gradient distribution resulted in dual-nature changes, leading to a deterioration in the color rendering index and an increase in the correlated color temperature, while also improving the DR-NIR band ratio. The reabsorption caused by the partial overlap between the excitation band of the DR-NIR particles and the emission band of the other particles enhanced the radiant power at 707 nm. Distributing DR-NIR phosphor particles closer to the chip effectively amplified this effect. The proposed model and its results provide a solution for the forward design of particle distributions in fluorescent films to improve the luminous performance of DR-NIR pc-wLEDs.
Citation: Micromachines
PubDate: 2024-08-15
DOI: 10.3390/mi15081035
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1036: Multi-Channel Microscale Nerve Cuffs
for Spatially Selective Neuromodulation
Authors: Morgan Riley, FNU Tala, Katherine J. Johnson, Benjamin C. Johnson
First page: 1036
Abstract: Peripheral nerve modulation via electrical stimulation shows promise for treating several diseases, but current approaches lack selectivity, leading to side effects. Exploring selective neuromodulation with commercially available nerve cuffs is impractical due to their high cost and limited spatial resolution. While custom cuffs reported in the literature achieve high spatial resolutions, they require specialized microfabrication equipment and significant effort to produce even a single design. This inability to rapidly and cost-effectively prototype novel cuff designs impedes research into selective neuromodulation therapies in acute studies. To address this, we developed a reproducible method to easily create multi-channel epineural nerve cuffs for selective fascicular neuromodulation. Leveraging commercial flexible printed circuit (FPC) technology, we created cuffs with high spatial resolution (50 μm) and customizable parameters like electrode size, channel count, and cuff diameter. We designed cuffs to accommodate adult mouse or rat sciatic nerves (300–1500 μm diameter). We coated the electrodes with PEDOT:PSS to improve the charge injection capacity. We demonstrated selective neuromodulation in both rats and mice, achieving preferential activation of the tibialis anterior (TA) and lateral gastrocnemius (LG) muscles. Selectivity was confirmed through micro-computed tomography (μCT) and quantified through a selectivity index. These results demonstrate the potential of this fabrication method for enabling selective neuromodulation studies while significantly reducing production time and costs compared to traditional approaches.
Citation: Micromachines
PubDate: 2024-08-15
DOI: 10.3390/mi15081036
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1037: Development of a Microbioreactor for
Bacillus subtilis Biofilm Cultivation
Authors: Mojca Seručnik, Iztok Dogsa, Lan Julij Zadravec, Ines Mandic-Mulec, Polona Žnidaršič-Plazl
First page: 1037
Abstract: To improve our understanding of Bacillus subtilis growth and biofilm formation under different environmental conditions, two versions of a microfluidic reactor with two channels separated by a polydimethylsiloxane (PDMS) membrane were developed. The gas phase was introduced into the channel above the membrane, and oxygen transfer from the gas phase through the membrane was assessed by measuring the dissolved oxygen concentration in the liquid phase using a miniaturized optical sensor and oxygen-sensitive nanoparticles. B. subtilis biofilm formation was monitored in the growth channels of the microbioreactors, which were designed in two shapes: one with circular extensions and one without. The volumes of these microbioreactors were (17 ± 4) μL for the reactors without extensions and (28 ± 4) μL for those with extensions. The effect of microbioreactor geometry and aeration on B. subtilis biofilm growth was evaluated by digital image analysis. In both microbioreactor geometries, stable B. subtilis biofilm formation was achieved after 72 h of incubation at a growth medium flow rate of 1 μL/min. The amount of oxygen significantly influenced biofilm formation. When the culture was cultivated with a continuous air supply, biofilm surface coverage and biomass concentration were higher than in cultivations without aeration or with a 100% oxygen supply. The channel geometry with circular extensions did not lead to a higher total biomass in the microbioreactor compared to the geometry without extensions.
Citation: Micromachines
PubDate: 2024-08-15
DOI: 10.3390/mi15081037
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1038: The Performance and Fabrication of 3D
Variable Cross-Section Channel for Passive Microfluidic Control
Authors: Wenjie Qian, Zhou Zhou, Qing Wang, Wei Shi, Manman Xu, Daoheng Sun
First page: 1038
Abstract: Passive fluid control has mostly been used for valves, pumps, and mixers in microfluidic systems. The basic principle is to generate localized losses in special channel structures, such as branches, grooves, or spirals. The flow field in two-dimensional space can be easily calculated using the typical Stokes formula, but it is challenging in three-dimensional space. Moreover, the flow field with periodic variable cross-sections channeled of polyhedral units has been neglected in this research field due to previous limitations in manufacturing technology. With the continuous progress of 3D printing technology, the field of microfluidic devices ushered in a new era of manufacturing three-dimensional irregular channels. In this study, we present finite analysis results for a periodic nodular-like channel. The experiments involve variations in the Reynold number (Re), periodic frequency, and comparative analyses with conventional structures. The findings indicate that this variable 3D cross-section structure can readily achieve performance comparable to other passive fluid control methods in valve applications. A 3D model of the periodic tetrahedron channel was fabricated using 3D printing to validate these conclusions. This research has the potential to significantly enhance the performance of passive fluid control units that have long been constrained by manufacturing dimensions.
Citation: Micromachines
PubDate: 2024-08-15
DOI: 10.3390/mi15081038
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1039: Design, Modeling, and Testing of a
Long-Stroke Fast Tool Servo Based on Corrugated Flexure Units
Authors: Ning Chen, Zhichao Wen, Jiateng Rong, Chuan Tian, Xianfu Liu
First page: 1039
Abstract: To further enhance the performance of the fast tool servo (FTS) system in terms of stroke, load capacity, and application area, this paper proposes a novel fast tool servo device driven by a voice coil motor (VCM), based on a three-segment uniform corrugated flexure (CF) guiding mechanism, with a large stroke, high accuracy, and high dynamics. To describe the unified static characteristics of such device, the compliance matrix method is applied to establish its model, where the influence of CF beam structural parameters on the FTS device is investigated in detail. Furthermore, resolution and positioning accuracy tests are conducted to validate the features of the system. The testing results indicate that the maximum stroke of the FTS device is up to 3.5 mm and the positioning resolution values are 3.6 μm and 2.4 μm for positive and negative stroke, respectively, which further verifies the device’s effectiveness and promising application prospect in ultra-precision microstructure machining.
Citation: Micromachines
PubDate: 2024-08-15
DOI: 10.3390/mi15081039
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1040: The Impact of Titanium Hydroxyapatite
Doping on the Mechanical and Biological Properties of Photocured Resin
Authors: Xiaopan Li, Chao Yao, Junfu Shen, Siqi Zhu, Yiyun Kong, Chun Yao, Yuankai Zhou, Jing Xia
First page: 1040
Abstract: Photocured resin materials are widely used in various fields, such as 3D printing, medical applications, and dentistry. However, the strength, wear resistance, and antibacterial properties of photocured resin are relatively limited, rendering it susceptible to potential failures. In this recent study, photocured composite resins incorporating titanium-doped hydroxyapatite (Ti-HAp) were fabricated to investigate their mechanical and biological properties. It was found that the hardness and wear resistance increased with the addition of an appropriate amount of hydroxyapatite (HAp). Specifically, the 6wt%HAp resin demonstrated superior hardness. Compared with the 6wt%HAp resin, the acid resistance and wear resistance improved when an appropriate amount of Ti-HAp was added. Notably, the resin containing 0.56%Ti-HAp demonstrated superior wear resistance. Additionally, the antibacterial performance improved with higher titanium (Ti) content, showcasing a 71.9% improvement in the resin containing 1.37%Ti-HAp compared with the 6wt%HAp resin, alongside commendable remineralization capabilities. In summary, the Ti-HAp composite resin showed enhanced mechanical and biological properties, meeting clinical standards in terms of mechanical and antibacterial properties.
Citation: Micromachines
PubDate: 2024-08-16
DOI: 10.3390/mi15081040
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1041: A Systematic Review of Modeling and
Simulation for Precision Diamond Wire Sawing of Monocrystalline Silicon
Authors: Ansheng Li, Hongyan Wang, Shunchang Hu, Yu Zhou, Jinguang Du, Lianqing Ji, Wuyi Ming
First page: 1041
Abstract: Precision processing of monocrystalline silicon presents significant challenges due to its unique crystal structure and chemical properties. Effective modeling and simulation are essential for advancing the understanding of the manufacturing process, optimizing design, and refining production parameters to enhance product quality and performance. This review provides a comprehensive analysis of the modeling and simulation techniques applied in the precision machining of monocrystalline silicon using diamond wire sawing. Firstly, the principles of mathematical analytical model, molecular dynamics, and finite element methods as they relate to monocrystalline silicon processing are outlined. Subsequently, the review explores how mathematical analytical models address force-related issues in this context. Molecular dynamics simulations provide valuable insights into atomic-scale processes, including subsurface damage and stress distribution. The finite element method is utilized to investigate temperature variations and abrasive wear during wire cutting. Furthermore, similarities, differences, and complementarities among these three modeling approaches are examined. Finally, future directions for applying these models to precision machining of monocrystalline silicon are discussed.
Citation: Micromachines
PubDate: 2024-08-17
DOI: 10.3390/mi15081041
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1042: Study on 1550 nm Human Eye-Safe
High-Power Tunnel Junction Quantum Well Laser
Authors: Qi Wu, Dongxin Xu, Xuehuan Ma, Zaijin Li, Yi Qu, Zhongliang Qiao, Guojun Liu, Zhibin Zhao, Lina Zeng, Hao Chen, Lin Li, Lianhe Li
First page: 1042
Abstract: Falling within the safe bands for human eyes, 1550 nm semiconductor lasers have a wide range of applications in the fields of LIDAR, fast-ranging long-distance optical communication, and gas sensing. The 1550 nm human eye-safe high-power tunnel junction quantum well laser developed in this paper uses three quantum well structures connected by two tunnel junctions as the active region; photolithography and etching were performed to form two trenches perpendicular to the direction of the epitaxial layer growth with a depth exceeding the tunnel junction, and the trenches were finally filled with oxides to reduce the extension current. Finally, a 1550 nm InGaAlAs quantum well laser with a pulsed peak power of 31 W at 30 A (10 KHz, 100 ns) was realized for a single-emitter laser device with an injection strip width of 190 μm, a ridge width of 300 μm, and a cavity length of 2 mm, with a final slope efficiency of 1.03 W/A, and with a horizontal divergence angle of about 13° and a vertical divergence angle of no more than 30°. The device has good slope efficiency, and this 100 ns pulse width can be effectively applied in the fields of fog-transparent imaging sensors and fast headroom ranging radar areas.
Citation: Micromachines
PubDate: 2024-08-17
DOI: 10.3390/mi15081042
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1043: Nonlinear Optical Response of
Au/CsPbI3 Quantum Dots and Its Laser Modulation Characteristics at 2.7
μm
Authors: Mengqi Lv, Jin Zhao, Leilei Guo, Yanxu Zhang, Qiuling Zhao, Lihua Teng, Maorong Wang, Shuaiyi Zhang, Xia Wang
First page: 1043
Abstract: A passively Q-switched Er:YAP laser of 2.7 µm, utilizing Au-doped CsPbI3 quantum dots (QDs) as a saturable absorber (SA), was realized. It was operated stably with a minimum pulse width of 185 ns and a maximum repetition rate of 480 kHz. The maximum pulse energy and the maximum peak power were 0.6 μJ and 2.9 W, respectively, in the Q-switched operation. The results show that the CsPbI3 QDs SA exhibits remarkable laser modulation properties at ~3 μm.
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081043
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1044: Research on the Key Technology of a
Fluorescence Detection Device Using the RT-LAMP Method for Instant
Detection
Authors: Hongzhuang Guo, Ping Gong, Tingting Sun, Xin Wang, Hao Zhang
First page: 1044
Abstract: As of 31 October 2023, there have been 771,795,258 confirmed cases of COVID-19 globally. Developing simple, portable, and reliable testing devices has become increasingly important. This paper presents a point-of-care testing (POCT) device for COVID-19 based on the dual-excitation fluorescence RT-LAMP method, which is derived from the principles of RT-LAMP-based COVID-19 detection kits available in the market. The key design solutions of the device were simulated and modeled. Key performance metrics such as detection repeatability and linearity were validated. Comparative experiments with the RT-qPCR detection method were conducted to verify the accuracy and reliability of the device. Additionally, the device’s detection sensitivity and accuracy were assessed. Experimental results show that the repeatability coefficient of variation (CV) value is ≤0.09%; the linearity R2 for the FAM channel is 0.9977 and that for the HEX channel is 0.9899; it exhibits good anti-interference performance, with negligible cross-channel interference; the temperature stability is ±0.062 °C, the temperature accuracy is less than 0.2 °C, and there is no significant temperature overshoot during the heating process. Compared with the real-time quantitative PCR (RT-qPCR) instrument, the positive agreement rate is 100% and the negative agreement rate is 95.0%. This research provides a foundational basis for the development of equipment for the prevention of infectious diseases and clinical diagnostics.
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081044
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1045: Development of a Portable Residual
Chlorine Detection Device with a Combination of Microfluidic Chips and
LS-BP Algorithm to Achieve Accurate Detection of Residual Chlorine in
Water
Authors: Tongfei Wang, Jiping Niu, Haoran Pang, Xiaoyu Meng, Ruqian Sun, Jiaqing Xie
First page: 1045
Abstract: Chlorine is widely used for sterilization and disinfection of water, but the presence of excess residual chlorine in water poses a substantial threat to human health. At present, there is no portable device which can achieve accurate, rapid, low-cost, and convenient detection of residual chlorine in water. Therefore, it is necessary to develop a device that can perform accurate, rapid, low-cost, and convenient detection of residual chlorine in water. In this study, a portable residual chlorine detection device was developed. A microfluidic chip was studied to achieve efficient mixing of two-phase flow. This microfluidic chip was used for rapid mixing of reagents in the portable residual chlorine detection device, reducing the consumption of reagents, detection time, and device volume. A deep learning algorithm was proposed for predicting residual chlorine concentration in water, achieving precise detection. Firstly, the microfluidic chip structure for detecting mixed reagents was optimized, and the microfluidic chip was fabricated by a 3D-printing method. Secondly, a deep learning (LS-BP) algorithm was constructed and proposed for predicting residual chlorine concentration in water, which can realize dual-channel signal reading. Thirdly, the corresponding portable residual chlorine detection device was developed, and the detection device was compared with residual chlorine detection devices and methods in other studies. The comparison results indicate that the portable residual chlorine detection device has high detection accuracy, fast detection speed, low cost, and good convenience. The excellent performance of the portable residual chlorine detection device makes it suitable for detecting residual chlorine in drinking water, swimming pool water, aquaculture and other fields.
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081045
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1046: Electromigration Analysis for
Interconnects Using Improved Graph Convolutional Network with Edge Feature
Aggregation
Authors: Ruqing Ye, Xiaoming Chen
First page: 1046
Abstract: Electromigration (EM) is a critical reliability issue in integrated circuits and is becoming increasingly significant as fabrication technology nodes continue to advance. The analysis of the hydrostatic stress, which is paramount in electromigration studies, typically involves solving complex physical equations (partial differential equations, or PDEs in this case), which is time consuming, inefficient and not practical for full-chip EM analysis. In this paper, a novel approach is proposed, conceptualizing circuit interconnect trees as a graph within a graph neural network framework. Using finite element solution software, ground truth hydrostatic stress values were obtained to construct a dataset of interconnected trees with hydrostatic stress values for each node. An improved Graph Convolutional Network (GCN) augmented with edge feature aggregation and attention mechanism was then trained employing the dataset, yielding a model capable of predicting hydrostatic stress values for nodes in an interconnect tree. The results show that our model demonstrated a 15% improvement in the Root Mean Square Error (RMSE) compared to the original GCN model and improved the solution speed greatly compared to traditional finite element software.
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081046
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1047: Design and Fabrication of Tryptophan
Sensor Using Voltammetric Method
Authors: Mohd Quasim Khan, Khursheed Ahmad, Rais Ahmad Khan
First page: 1047
Abstract: L-tryptophan is an amino acid that significantly impacts metabolic activity in both humans and herbivorous animals. It is also known as a precursor for melatonin and serotonin, and its levels must be regulated in the human body. Therefore, there is a need to develop a cost-effective, simple, sensitive, and selective method for detecting L-tryptophan. Herein, we report the fabrication of an L-tryptophan sensor using a nickel-doped tungsten oxide ceramic-modified electrode. The Ni-WO3 was synthesized using simple strategies and characterized by various advanced techniques such as powder X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and photoelectron X-ray spectroscopy. Furthermore, a glassy carbon electrode was modified with the synthesized Ni-WO3 and explored as the L-tryptophan (L-TRP) sensor. Cyclic voltammetry and differential pulse voltammetry were used to investigate the sensing ability of the modified electrode (Ni-WO3/GC). The Ni-WO3/GC exhibited an excellent limit of detection of 0.4 µM with a good dynamic linear range. The Ni-WO3/GC also demonstrated excellent selectivity in the presence of various electroactive molecules. The Ni-WO3/GC also showed decent reproducibility, repeatability, stability, and storage stability. This work proposes the fabrication of novel Ni-WO3/GC for the sensing of L-tryptophan. So far, no report is available on the use of Ni-WO3/GC for the sensing of L-TRP. This is the first report on the use of Ni-WO3/GC for the sensing of L-TRP sensing applications.
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081047
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1048: Editorial for the Special Issue on
Exploring IoT Sensors and Their Applications: Advancements, Challenges,
and Opportunities in Smart Environments
Authors: Lei Jing, Yoshinori Matsumoto, Zhan Zhang
First page: 1048
Abstract: As the editor of the Special Issue on “Exploring IoT Sensors and Their Applications: Advancements, Challenges, and Opportunities in Smart Environments”, I am delighted to present this collection of groundbreaking research that addresses the emerging needs and challenges in the field of IoT sensors and smart environments [...]
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081048
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1049: Resonant MEMS Accelerometer with Low
Authors: Jiaqi Miao, Pinghua Li, Mingchen Lv, Suzhen Nie, Yang Liu, Ruimei Liang, Weijiang Ma, Xuye Zhuang
First page: 1049
Abstract: This article proposes a low cross-axis sensitivity resonant MEMS(Micro-Electro-Mechanical Systems) accelerometer that is optimized based on the BP and NSGA-II algorithms. When resonant accelerometers are used in seismic monitoring, automotive safety systems, and navigation applications, high immunity and low cross-axis sensitivity are required. To improve the high immunity of the accelerometer, a coupling structure is introduced. This structure effectively separates the symmetric and antisymmetric mode frequencies of the DETF resonator and prevents mode coupling. To obtain higher detection accuracy and low cross-axis sensitivity, a decoupling structure is introduced. To find the optimal dimensional parameters of the decoupled structure, the BP and NSGA-II algorithms are used to optimize the dimensional parameters of the decoupled structure. The optimized decoupled structure has an axial stiffness of 6032.21 N/m and a transverse stiffness of 6.29 N/m. The finite element analysis results show that the sensitivity of the accelerometer is 59.1 Hz/g (Y-axis) and 59 Hz/g (X-axis). Cross-axis sensitivity is 0.508% (Y-axis) and 0.339% (X-axis), which is significantly lower than most resonant accelerometers. The coupling structure and optimization method proposed in this paper provide a new solution for designing resonant accelerometers with high interference immunity and low cross-axis sensitivity.
Citation: Micromachines
PubDate: 2024-08-18
DOI: 10.3390/mi15081049
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1050: Development of a Fast Positioning
Platform with a Large Stroke Based on a Piezoelectric Actuator for
Precision Machining
Authors: Gaofeng Hu, Wendong Xin, Min Zhang, Guangjun Chen, Jia Man, Yanling Tian
First page: 1050
Abstract: In this paper, a fast positioning platform (FPP) is proposed, able to meet simultaneously the requirements of large stroke and high frequency response, developed based on a PZT (piezoelectric actuator) and a quad-parallel flexible mechanism, for application in precision machining. The FPP is driven by a high-stiffness PZT and guided by a flexible hinge-based mechanism with a quad-parallel flexible hinge. The proposed quad-parallel flexible hinge mechanism can provide excellent planar motion capability with high stiffness and good guiding performance, thus guaranteeing outstanding dynamics characteristics. The mechanical model was established, the input and output characteristics of the FPP were analyzed, and the working range (output displacement and frequency) of the FPP was determined. Based on the mechanical model and the input and output characteristics of the FPP, the design method is described for of the proposed FPP, which is capable of achieving a large stroke while responding at a high frequency. The characteristics of the FPP were investigated using finite element analysis (FEA). Experiments were conducted to examine the performance of the FPP; the natural frequency of the FPP was 1315.6 Hz, while the maximum output displacement and the motion resolution of the FPP in a static state were 53.13 μm and 5 nm, respectively. Step response testing showed that under a step magnitude of 50 μm, the stabilization times for the falling and rising edges of the moving platform were 37 ms and 26 ms, respectively. The tracking errors were about ±1.96 μm and ±0.59 μm when the amplitude and frequency of the signal were 50 μm, 50 Hz and 10 μm, 200 Hz, respectively. The FPP showed excellent performance in terms of fast response and output displacement. The cutting test results indicated that compared with the uncontrolled condition, the values of surface roughness under controlled conditions decreased by 23.9% and 12.7% when the cutting depths were 5 μm and 10 μm, respectively. The developed FPP device has excellent precision machining performance.
Citation: Micromachines
PubDate: 2024-08-19
DOI: 10.3390/mi15081050
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1051: A Broadband MS-Based Circularly
Polarized Antenna Array Using Sequential-Phase Feeding Network
Authors: Hung Pham-Duy, Dat Nguyen-Tien, Thanh Nguyen-Ngoc, Duc-Nguyen Tran-Viet, Thai Nguyen-Dinh, Tuyen Danh Pham, Hung Tran-Huy
First page: 1051
Abstract: This paper introduces the design of a circularly polarized metasurface-based antenna array for C-band satellite applications that owns broadband operation and high gain characteristics. The single radiating element comprises a Y-shape patch and an above-placed 2 × 2 unit-cell metasurface. Further improvement in operating bandwidth and broadside gain is achieved by arranging four single elements in a 2 × 2 configuration and a sequential-phase feed network. A prototype has been fabricated and measured to validate the feasibility of the proposed antenna array. The measured operating bandwidth is 20% (4.50–5.50 GHz), which is an overlap between a −10 dB impedance bandwidth of 29.8% (4.50–5.99 GHz) and a 3 dB axial ratio bandwidth of 20% (4.50–5.50 GHz). Across this operating band, the peak broadside gain is 10.5 dBi. Compared with the recently published studies, the proposed array is a prominent design for producing a wide operating bandwidth and relatively high gains while maintaining the overall compact dimensions.
Citation: Micromachines
PubDate: 2024-08-20
DOI: 10.3390/mi15081051
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1052: Fabrication of Medium Mn Advanced
High-Strength Steel with Excellent Mechanical Properties by Friction Stir
Processing
Authors: Yonggang Yang, Wangnan Zuo, Yu Liu, Yunzong Ge, Zhiqiang Yang, Jiansheng Han, Zhenli Mi
First page: 1052
Abstract: Friction stir processing (FSP) manufacturing technology was used to fabricate medium Mn advanced high-strength steel in this study. The mechanical properties and microstructure of the steel fabricated using FSP were investigated. The steel obtained a total elongation of 35.1% and a tensile strength of 1034.6 MPa, which is about 59% higher than that of the steel without FSP. After FSP, a gradient structure occurs along the thickness direction. Specifically, across the thickness direction from the base material zone to the transition zone and finally to the stirring zone, both the grain size and austenite fraction decrease while the dislocation density increases, which results from the simultaneous effect of severe plastic deformation and recrystallization during FSP. Due to the gradient structure, an obvious difference in the strain across the thickness direction of the steel occurs during the deformation process, resulting in significant hetero-deformation-induced (HDI) strengthening. The deformation mechanism analysis reveals that HDI strengthening and dislocation strengthening are the main factors in the improvement in the strength–ductility balance. The obtained knowledge sheds light on the process of fabricating medium Mn steels with excellent properties using FSP manufacturing technology.
Citation: Micromachines
PubDate: 2024-08-21
DOI: 10.3390/mi15081052
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1053: Online Handwriting Recognition Method
with a Non-Inertial Reference Frame Based on the Measurement of Linear
Accelerations and Differential Geometry: An Alternative to Quaternions
Authors: Griselda Stephany Abarca Jiménez, Carmen Caritina Muñoz Garnica, Mario Alfredo Reyes Barranca, Jesús Mares Carreño, Manuel Vladimir Vega Blanco, Francisco Gutiérrez Galicia
First page: 1053
Abstract: This work describes a mathematical model for handwriting devices without a specific reference surface (SRS). The research was carried out on two hypotheses: the first considers possible circular segments that could be made during execution for the reconstruction of the trace, and the second is the combination of lines and circles. The proposed system has no flat reference surface, since the sensor is inside the pencil that describes the trace, not on the surface as in tablets or cell phones. An inertial sensor was used for the measurements, in this case, a commercial Micro-Electro Mechanical sensor of linear acceleration. The tracking device is an IMU sensor and a processing card that allows inertial measurements of the pen during on-the-fly tracing. It is essential to highlight that the system has a non-inertial reference frame. Comparing the two proposed models shows that it is possible to construct shapes from curved lines and that the patterns obtained are similar to what is recognized; this method provides an alternative to quaternion calculus for poorly specified orientation problems.
Citation: Micromachines
PubDate: 2024-08-21
DOI: 10.3390/mi15081053
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1054: Fabrication of Two-Layer Microfluidic
Devices with Porous Electrodes Using Printed Sacrificial Layers
Authors: Kosuke Ino, An Konno, Yoshinobu Utagawa, Taiyo Kanno, Kazuyuki Iwase, Hiroya Abe, Hitoshi Shiku
First page: 1054
Abstract: Two-layer microfluidic devices with porous membranes have been widely used in bioapplications such as microphysiological systems (MPS). Porous electrodes, instead of membranes, have recently been incorporated into devices for electrochemical cell analysis. Generally, microfluidic channels are prepared using soft lithography and assembled into two-layer microfluidic devices. In addition to soft lithography, three-dimensional (3D) printing has been widely used for the direct fabrication of microfluidic devices because of its high flexibility. However, this technique has not yet been applied to the fabrication of two-layer microfluidic devices with porous electrodes. This paper proposes a novel fabrication process for this type of device. In brief, Pluronic F-127 ink was three-dimensionally printed in the form of sacrificial layers. A porous Au electrode, fabricated by sputtering Au on track-etched polyethylene terephthalate membranes, was placed between the top and bottom sacrificial layers. After covering with polydimethylsiloxane, the sacrificial layers were removed by flushing with a cold solution. To the best of our knowledge, this is the first report on the sacrificial approach-based fabrication of two-layer microfluidic devices with a porous electrode. Furthermore, the device was used for electrochemical assays of serotonin and could successfully measure concentrations up to 5 µM. In the future, this device can be used for MPS applications.
Citation: Micromachines
PubDate: 2024-08-22
DOI: 10.3390/mi15081054
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1055: Innovative Integration of Dual Quantum
Cascade Lasers on Silicon Photonics Platform
Authors: Dongbo Wang, Harindra Kumar Kannojia, Pierre Jouy, Etienne Giraud, Kaspar Suter, Richard Maulini, David Gachet, Léo Hetier, Geert Van Steenberge, Bart Kuyken
First page: 1055
Abstract: For the first time, we demonstrate the hybrid integration of dual distributed feedback (DFB) quantum cascade lasers (QCLs) on a silicon photonics platform using an innovative 3D self-aligned flip-chip assembly process. The QCL waveguide geometry was predesigned with alignment fiducials, enabling a sub-micron accuracy during assembly. Laser oscillation was observed at the designed wavelength of 7.2 μm, with a threshold current of 170 mA at room temperature under pulsed mode operation. The optical output power after an on-chip beam combiner reached sub-milliwatt levels under stable continuous wave operation at 15 °C. The specific packaging design miniaturized the entire light source by a factor of 100 compared with traditional free-space dual lasers module. Divergence values of 2.88 mrad along the horizontal axis and 1.84 mrad along the vertical axis were measured after packaging. Promisingly, adhering to i-line lithography and reducing the reliance on high-end flip-chip tools significantly lowers the cost per chip. This approach opens new avenues for QCL integration on silicon photonic chips, with significant implications for portable mid-infrared spectroscopy devices.
Citation: Micromachines
PubDate: 2024-08-22
DOI: 10.3390/mi15081055
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1056: Bi-Directional and
Operand-Controllable In-Memory Computing for Boolean Logic and Search
Operations with Row and Column Directional SRAM (RC-SRAM)
Authors: Han Xiao, Ruiyong Zhao, Yulan Liu, Yuanzhen Liu, Jing Chen
First page: 1056
Abstract: The von Neumann architecture is no longer sufficient for handling large-scale data. In-memory computing has emerged as the potent method for breaking through the memory bottleneck. A new 10T SRAM bitcell with row and column control lines called RC-SRAM is proposed in this article. The architecture based on RC-SRAM can achieve bi-directional and operand-controllable logic-in-memory and search operations through different signal configurations, which can comprehensively respond to various occasions and needs. Moreover, we propose threshold-controlled logic gates for sensing, which effectively reduces the circuit area and improves accuracy. We validate the RC-SRAM with a 28 nm CMOS technology, and the results show that the circuits are not only full featured and flexible for customization but also have a significant increase in the working frequency. At VDD = 0.9 V and T = 25 °C, the bi-directional search frequency is up to 775 MHz and 567 MHz, and the speeds for row and column Boolean logic reach 759 MHz and 683 MHz.
Citation: Micromachines
PubDate: 2024-08-22
DOI: 10.3390/mi15081056
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1057: Enhancing Magnetic Micro- and
Nanoparticle Separation with a Cost-Effective Microfluidic Device
Fabricated by Laser Ablation of PMMA
Authors: Cristian F. Rodríguez, Paula Guzmán-Sastoque, Carolina Muñoz-Camargo, Luis H. Reyes, Johann F. Osma, Juan C. Cruz
First page: 1057
Abstract: Superparamagnetic iron oxide micro- and nanoparticles have significant applications in biomedical and chemical engineering. This study presents the development and evaluation of a novel low-cost microfluidic device for the purification and hyperconcentration of these magnetic particles. The device, fabricated using laser ablation of polymethyl methacrylate (PMMA), leverages precise control over fluid dynamics to efficiently separate magnetic particles from non-magnetic ones. We assessed the device’s performance through Multiphysics simulations and empirical tests, focusing on the separation of magnetite nanoparticles from blue carbon dots and magnetite microparticles from polystyrene microparticles at various total flow rates (TFRs). For nanoparticle separation, the device achieved a recall of up to 93.3 ± 4% and a precision of 95.9 ± 1.2% at an optimal TFR of 2 mL/h, significantly outperforming previous models, which only achieved a 50% recall. Microparticle separation demonstrated an accuracy of 98.1 ± 1% at a TFR of 2 mL/h in both simulations and experimental conditions. The Lagrangian model effectively captured the dynamics of magnetite microparticle separation from polystyrene microparticles, with close agreement between simulated and experimental results. Our findings underscore the device’s robust capability in distinguishing between magnetic and non-magnetic particles at both micro- and nanoscales. This study highlights the potential of low-cost, non-cleanroom manufacturing techniques to produce high-performance microfluidic devices, thereby expanding their accessibility and applicability in various industrial and research settings. The integration of a continuous magnet, as opposed to segmented magnets in previous designs, was identified as a key factor in enhancing magnetic separation efficiency.
Citation: Micromachines
PubDate: 2024-08-22
DOI: 10.3390/mi15081057
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1058: Enhancing Flexible Neural Probe
Performance via Platinum Deposition: Impedance Stability under Various
Conditions and In Vivo Neural Signal Monitoring
Authors: Daerl Park, Hyeonyeong Jeong, Jungsik Choi, Juyeon Han, Honglin Piao, Jaehyun Kim, Seonghoon Park, Mingu Song, Dowoo Kim, Jaesuk Sung, Eunji Cheong, Heonjin Choi
First page: 1058
Abstract: Monitoring neural activity in the central nervous system often utilizes silicon-based microelectromechanical system (MEMS) probes. Despite their effectiveness in monitoring, these probes have a fragility issue, limiting their application across various fields. This study introduces flexible printed circuit board (FPCB) neural probes characterized by robust mechanical and electrical properties. The probes demonstrate low impedance after platinum coating, making them suitable for multiunit recordings in awake animals. This capability allows for the simultaneous monitoring of a large population of neurons in the brain, including cluster data. Additionally, these probes exhibit no fractures, mechanical failures, or electrical issues during repeated-bending tests, both during handling and monitoring. Despite the possibility of using this neural probe for signal measurement in awake animals, simply applying a platinum coating may encounter difficulties in chronic tests and other applications. Furthermore, this suggests that FPCB probes can be advanced by any method and serve as an appropriate type of tailorable neural probes for monitoring neural systems in awake animals.
Citation: Micromachines
PubDate: 2024-08-22
DOI: 10.3390/mi15081058
Issue No: Vol. 15, No. 8 (2024)
- Micromachines, Vol. 15, Pages 1059: Deep Learning-Assisted
Smartphone-Based Electrochemiluminescence Visual Monitoring Biosensor: A
Fully Integrated Portable Platform
Authors: Manish Bhaiyya, Prakash Rewatkar, Amit Pimpalkar, Dravyansh Jain, Sanjeet Kumar Srivastava, Jitendra Zalke, Jayu Kalambe, Suresh Balpande, Pawan Kale, Yogesh Kalantri, Madhusudan B. Kulkarni
First page: 1059
Abstract: A novel, portable deep learning-assisted smartphone-based electrochemiluminescence (ECL) cost-effective (~10$) sensing platform was developed and used for selective detection of lactate. Low-cost, fast prototyping screen printing and wax printing methods with paper-based substrate were used to fabricate miniaturized single-pair electrode ECL platforms. The lab-made 3D-printed portable black box served as a reaction chamber. This portable platform was integrated with a smartphone and a buck-boost converter, eliminating the need for expensive CCD cameras, photomultiplier tubes, and bulky power supplies. This advancement makes this platform ideal for point-of-care testing applications. Foremost, the integration of a deep learning approach served to enhance not just the accuracy of the ECL sensors, but also to expedite the diagnostic procedure. The deep learning models were trained (3600 ECL images) and tested (900 ECL images) using ECL images obtained from experimentation. Herein, for user convenience, an Android application with a graphical user interface was developed. This app performs several tasks, which include capturing real-time images, cropping them, and predicting the concentration of required bioanalytes through deep learning. The device’s capability to work in a real environment was tested by performing lactate sensing. The fabricated ECL device shows a good liner range (from 50 µM to 2000 µM) with an acceptable limit of detection value of 5.14 µM. Finally, various rigorous analyses, including stability, reproducibility, and unknown sample analysis, were conducted to check device durability and stability. Therefore, the developed platform becomes versatile and applicable across various domains by harnessing deep learning as a cutting-edge technology and integrating it with a smartphone.
Citation: Micromachines
PubDate: 2024-08-22
DOI: 10.3390/mi15081059
Issue No: Vol. 15, No. 8 (2024)
