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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. 14, Pages 1100: Improving Performance of Al2O3/AlN/GaN
MIS HEMTs via In Situ N2 Plasma Annealing
Authors: Mengyuan Sun, Luyu Wang, Penghao Zhang, Kun Chen
First page: 1100
Abstract: A novel monocrystalline AlN interfacial layer formation method is proposed to improve the device performance of the fully recessed-gate Al2O3/AlN/GaN Metal-Insulator-Semiconductor High Electron Mobility Transistors (MIS-HEMTs), which is achieved by plasma-enhanced atomic layer deposition (PEALD) and in situ N2 plasma annealing (NPA). Compared with the traditional RTA method, the NPA process not only avoids the device damage caused by high temperatures but also obtains a high-quality AlN monocrystalline film that avoids natural oxidation by in situ growth. As a contrast with the conventional PELAD amorphous AlN, C-V results indicated a significantly lower interface density of states (Dit) in a MIS C-V characterization, which could be attributed to the polarization effect induced by the AlN crystal from the X-ray Diffraction (XRD) and Transmission Electron Microscope (TEM) characterizations. The proposed method could reduce the subthreshold swing, and the Al2O3/AlN/GaN MIS-HEMTs were significantly enhanced with ~38% lower on-resistance at Vg = 10 V. What is more, in situ NPA provides a more stable threshold voltage (Vth) after a long gate stress time, and ΔVth is inhibited by about 40 mV under Vg,stress = 10 V for 1000 s, showing great potential for improving Al2O3/AlN/GaN MIS-HEMT gate reliability.
Citation: Micromachines
PubDate: 2023-05-23
DOI: 10.3390/mi14061100
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1101: Enhanced Operational Characteristics
Attained by Applying HfO2 as Passivation in AlGaN/GaN
High-Electron-Mobility Transistors: A Simulation Study
Authors: Jun-Hyeok Choi, Woo-Seok Kang, Dohyung Kim, Ji-Hun Kim, Jun-Ho Lee, Kyeong-Yong Kim, Byoung-Gue Min, Dong Min Kang, Hyun-Seok Kim
First page: 1101
Abstract: This study investigates the operating characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) by applying HfO2 as the passivation layer. Before analyzing HEMTs with various passivation structures, modeling parameters were derived from the measured data of fabricated HEMT with Si3N4 passivation to ensure the reliability of the simulation. Subsequently, we proposed new structures by dividing the single Si3N4 passivation into a bilayer (first and second) and applying HfO2 to the bilayer and first passivation layer only. Ultimately, we analyzed and compared the operational characteristics of the HEMTs considering the basic Si3N4, only HfO2, and HfO2/Si3N4 (hybrid) as passivation layers. The breakdown voltage of the AlGaN/GaN HEMT having only HfO2 passivation was improved by up to 19%, compared to the basic Si3N4 passivation structure, but the frequency characteristics deteriorated. In order to compensate for the degraded RF characteristics, we modified the second Si3N4 passivation thickness of the hybrid passivation structure from 150 nm to 450 nm. We confirmed that the hybrid passivation structure with 350-nm-thick second Si3N4 passivation not only improves the breakdown voltage by 15% but also secures RF performance. Consequently, Johnson’s figure-of-merit, which is commonly used to judge RF performance, was improved by up to 5% compared to the basic Si3N4 passivation structure.
Citation: Micromachines
PubDate: 2023-05-23
DOI: 10.3390/mi14061101
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1102: Editorial for the Special Issue on
Optics and Photonics in Micromachines
Authors: Cuifang Kuang, Wei Zhao
First page: 1102
Abstract: Micromachines, as a platform for manipulation, assembling, detection and imaging, is a typical interdisciplinary field related to broad areas, e [...]
Citation: Micromachines
PubDate: 2023-05-23
DOI: 10.3390/mi14061102
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1103: Dynamic Characteristic Model of Giant
Magnetostrictive Transducer with Double Terfenol-D Rods
Authors: Yafang Li, Xia Dong, Xiaodong Yu
First page: 1103
Abstract: Giant magnetostrictive transducer can be widely used in active vibration control, micro-positioning mechanism, energy harvesting system, and ultrasonic machining. Hysteresis and coupling effects are present in transducer behavior. The accurate prediction of output characteristics is critical for a transducer. A dynamic characteristic model of a transducer is proposed, by providing a modeling methodology capable of characterizing the nonlinearities. To attain this objective, the output displacement, acceleration, and force are discussed, the effects of operating conditions on the performance of Terfenol-D are studied, and a magneto-mechanical model for the behavior of transducer is proposed. A prototype of the transducer is fabricated and tested to verify the proposed model. The output displacement, acceleration, and force have been theoretically and experimentally studied at different working conditions. The results show that, the displacement amplitude, acceleration amplitude, and force amplitude are about 49 μm, 1943 m/s2, and 20 N. The error between the model and experimental results are 3 μm, 57 m/s2, and 0.2 N. Calculation results and experimental results show a good agreement.
Citation: Micromachines
PubDate: 2023-05-24
DOI: 10.3390/mi14061103
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1104: High-Efficiency CsPbBr3 Light-Emitting
Diodes using One-Step Spin-Coating In Situ Dynamic Thermal Crystallization
Authors: Buyue Zhang, Chen Chen, Xinyu Chen
First page: 1104
Abstract: All-inorganic perovskite materials (such as CsPbBr3) have received widespread attention because of their better stability than hybrid counterparts, but their poor film morphology and crystalline quality limit their application in perovskite light-emitting devices (PeLEDs). Some previous studies have attempted to improve the morphology and crystalline quality of perovskite films by heating the substrate, but there are still some problems such as inaccurate temperature control, excessive temperature is not conducive to flexible applications, and the mechanism of action is not clear. In this work, we used a one-step spin-coating, low-temperature in situ thermally assisted crystallization process, in which the temperature was accurately monitored using a thermocouple in the range of 23–80 °C, and explored the effect of the in situ thermally assisted crystallization temperature on the crystallization of the all-inorganic perovskite material CsPbBr3 and the performance of PeLEDs. In addition, we focused on the influence mechanism for the in situ thermally assisted crystallization process on the surface morphology and phase composition of the perovskite films and promote its possible application in inkjet printing and scratch coating methods.
Citation: Micromachines
PubDate: 2023-05-24
DOI: 10.3390/mi14061104
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1105: Research on the Comparison Properties
of PDMS Specimens Demolding Processes and the Mechanical Performance of
Hollow-Solid Ratios of Flexible Telescopic Rods
Authors: Ruining Shang, Xiaona Li, Xiaogang Wu, Weiyi Chen
First page: 1105
Abstract: The main motivation of this work was to demonstrate a hollow telescopic rod structure that could be used for minimally invasive surgery. The telescopic rods were fabricated using 3D printing technology to make mold flips. During fabrication, differences in biocompatibility, light transmission, and ultimate displacement were compared between telescopic rods fabricated via different processes, so as to select the appropriate process. To achieve these goals, flexible telescopic rod structures were designed and 3D-printed molds were fabricated using Fused Deposition Modeling (FDM) and Stereolithography (SLA) techniques. The results showed that the three molding processes had no impact on the doping of the PDMS specimens. However, the FDM molding process had lower surface flatness accuracy compared to SLA. The SLA mold flip fabrication exhibited superior surface accuracy and light transmission compared to the other methods. The sacrificial template method and the use of HTL direct demolding technique had no significant impact on cellular activity and biocompatibility, but the mechanical properties of the PDMS specimens were weakened after swelling recovery. The height and radius of the hollow rod were found to have a significant impact on the mechanical properties of the flexible hollow rod. The hyperelastic model was fitted appropriately with the mechanical test results, and the ultimate elongation increased with an increase in hollow–solid ratios under the uniform force.
Citation: Micromachines
PubDate: 2023-05-24
DOI: 10.3390/mi14061105
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1106: Laser-Formed Sensors with Electrically
Conductive MWCNT Networks for Gesture Recognition Applications
Authors: Natalia A. Nikitina, Dmitry I. Ryabkin, Victoria V. Suchkova, Artem V. Kuksin, Evgeny S. Pyankov, Levan P. Ichkitidze, Aleksey V. Maksimkin, Evgeny P. Kitsyuk, Ekaterina A. Gerasimenko, Dmitry V. Telyshev, Ivan Bobrinetskiy, Sergey V. Selishchev, Alexander Yu. Gerasimenko
First page: 1106
Abstract: Currently, an urgent need in the field of wearable electronics is the development of flexible sensors that can be attached to the human body to monitor various physiological indicators and movements. In this work, we propose a method for forming an electrically conductive network of multi-walled carbon nanotubes (MWCNT) in a matrix of silicone elastomer to make stretchable sensors sensitive to mechanical strain. The electrical conductivity and sensitivity characteristics of the sensor were improved by using laser exposure, through the effect of forming strong carbon nanotube (CNT) networks. The initial electrical resistance of the sensors obtained using laser technology was ~3 kOhm (in the absence of deformation) at a low concentration of nanotubes of 3 wt% in composition. For comparison, in a similar manufacturing process, but without laser exposure, the active material had significantly higher values of electrical resistance, which was ~19 kOhm in this case. The laser-fabricated sensors have a high tensile sensitivity (gauge factor ~10), linearity of >0.97, a low hysteresis of 2.4%, tensile strength of 963 kPa, and a fast strain response of 1 ms. The low Young’s modulus values of ~47 kPa and the high electrical and sensitivity characteristics of the sensors made it possible to fabricate a smart gesture recognition sensor system based on them, with a recognition accuracy of ~94%. Data reading and visualization were performed using the developed electronic unit based on the ATXMEGA8E5-AU microcontroller and software. The obtained results open great prospects for the application of flexible CNT sensors in intelligent wearable devices (IWDs) for medical and industrial applications.
Citation: Micromachines
PubDate: 2023-05-24
DOI: 10.3390/mi14061106
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1107: A Novel Scheme for Full Bottom
Dielectric Isolation in Stacked Si Nanosheet Gate-All-Around Transistors
Authors: Jingwen Yang, Ziqiang Huang, Dawei Wang, Tao Liu, Xin Sun, Lewen Qian, Zhecheng Pan, Saisheng Xu, Chen Wang, Chunlei Wu, Min Xu, David Wei Zhang
First page: 1107
Abstract: In this paper, a novel scheme for source/drain-first (S/D-first) full bottom dielectric isolation (BDI), i.e., Full BDI_Last, with integration of a sacrificial Si0.5Ge0.5 layer was proposed and demonstrated in a stacked Si nanosheet gate-all-around (NS-GAA) device structure using TCAD simulations. The proposed full BDI scheme flow is compatible with the main process flow of NS-GAA transistor fabrication and provides a large window for process fluctuations, such as the thickness of the S/D recess. It is an ingenious solution to insert the dielectric material under the source, drain and gate regions to remove the parasitic channel. Moreover, because the S/D-first scheme decreases the problem of high-quality S/D epitaxy, the innovative fabrication scheme introduces full BDI formation after S/D epitaxy to mitigate the difficulty of providing stress engineering in the full BDI formation before S/D epitaxy (Full BDI_First). The electrical performance of Full BDI_Last is demonstrated by a 4.78-fold increase in the drive current compared to Full BDI_First. Furthermore, compared to traditional punch through stoppers (PTSs), the proposed Full BDI_Last technology could potentially provide an improved short channel behavior and good immunity against parasitic gate capacitance in NS-GAA devices. For the assessed inverter ring oscillator (RO), applying the Full BDI_Last scheme allows the operating speed to be increased by 15.2% and 6.2% at the same power, or alternatively enables an 18.9% and 6.8% lower power consumption at the same speed compared with the PTS and Full BDI_First schemes, respectively. The observations confirm that the novel Full BDI_Last scheme incorporated into an NS-GAA device can be utilized to enable superior characteristics to benefit the performance of integrated circuits.
Citation: Micromachines
PubDate: 2023-05-24
DOI: 10.3390/mi14061107
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1108: A Real Time Method Based on Deep
Learning for Reconstructing Holographic Acoustic Fields from Phased
Transducer Arrays
Authors: Shuai Wang, Xuewei Wang, Fucheng You, Yang Li, Han Xiao
First page: 1108
Abstract: Phased transducer arrays (PTA) can control ultrasonic waves to produce a holographic acoustic field. However, obtaining the phase of the corresponding PTA from a given holographic acoustic field is an inverse propagation problem, which is a mathematically unsolvable nonlinear system. Most of the existing methods use iterative methods, which are complex and time-consuming. To better solve this problem, this paper proposed a novel method based on deep learning to reconstruct the holographic sound field from PTA. For the imbalance and randomness of the focal point distribution in the holographic acoustic field, we constructed a novel neural network structure incorporating attention mechanisms to focus on useful focal point information in the holographic sound field. The results showed that the transducer phase distribution obtained from the neural network fully supports the PTA to generate the corresponding holographic sound field, and the simulated holographic sound field can be reconstructed with high efficiency and quality. The method proposed in this paper has the advantage of real-time performance that is difficult to achieve by traditional iterative methods and has the advantage of higher accuracy compared with the novel AcousNet methods.
Citation: Micromachines
PubDate: 2023-05-24
DOI: 10.3390/mi14061108
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1109: Theoretical Enhancement of the
Goos–Hänchen Shift with a Metasurface Based on Bound States in
the Continuum
Authors: Xiaowei Jiang, Bin Fang, Chunlian Zhan
First page: 1109
Abstract: The enhancement of the Goos–Hänchen (GH) shift has become a research hotspot due to its promoted application of the GH effect in various fields. However, currently, the maximum GH shift is located at the reflectance dip, making it difficult to detect GH shift signals in practical applications. This paper proposes a new metasurface to achieve reflection-type bound states in the continuum (BIC). The GH shift can be significantly enhanced by the quasi-BIC with a high quality factor. The maximum GH shift can reach more than 400 times the resonant wavelength, and the maximum GH shift is located exactly at the reflection peak with unity reflectance, which can be applied to detect the GH shift signal. Finally, the metasurface is used to detect the variation in the refractive index, and the sensitivity can reach 3.58 × 106 μm/RIU (refractive index unit) according to the simulation’s calculations. The findings provide a theoretical basis to prepare a metasurface with high refractive index sensitivity, a large GH shift, and high reflection.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061109
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1110: Flexible Pressure Sensors Based on
Microcrack Structure and Composite Conductive Mechanism for Medical
Robotic Applications
Authors: Qiang Zou, Yuheng Xie, Yunjiang Yin, Baoguo Liu, Yi Yu
First page: 1110
Abstract: With the advancement of intelligent medical robot technology, machine touch utilizing flexible sensors has emerged as a prominent research area. In this study, a flexible resistive pressure sensor was designed incorporating a microcrack structure with air pores and a composite conductive mechanism of silver/carbon. The aim was to achieve enhanced stability and sensitivity with the inclusion of macro through-holes (1–3 mm) to expand the sensitive range. This technology solution was specifically applied to the machine touch system of the B-ultrasound robot. Through meticulous experimentation, it was determined that the optimal approach involved uniformly blending ecoflex and nano carbon powder at a mass ratio of 5:1, and subsequently combining the mixture with an ethanol solution of silver nanowires (AgNWs) at a mass ratio of 6:1. This combination of components resulted in the fabrication of a pressure sensor with optimal performance. Under the pressure testing condition of 5 kPa, a comparison of the resistance change rate was conducted among samples using the optimal formulation from the three processes. It was evident that the sample of ecoflex-C-AgNWs/ethanol solution exhibited the highest sensitivity. Its sensitivity was increased by 19.5% compared to the sample (ecoflex-C) and by 11.3% compared to the sample (ecoflex-C-ethanol). The sample (ecoflex-C-AgNWs/ethanol solution), which only incorporated internal air pore microcracks without through-holes, exhibited sensitive response to pressures below 5 N. However, with the addition of through-holes, the measurement range of its sensitive response increased to 20 N, representing a 400% increase in the measurement range.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061110
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1111: Optimizing Processing Parameters and
Surface Quality of TC18 via Ultrasonic-Assisted Milling (UAM): An
Experimental Study
Authors: Guangxi Li, Weibo Xie, Hongtao Wang, Yongbo Chai, Shaolin Zhang, Liquan Yang
First page: 1111
Abstract: This study conducted longitudinal ultrasonic-assisted milling (UAM) tests and optimized a combination of milling technological parameters to achieve high-quality machining of TC18 titanium alloy. The motion paths of the cutter under the coupled superposition states of longitudinal ultrasonic vibration and end milling were analyzed. Based on the orthogonal test, the cutting forces, cutting temperatures, residual stresses, and surface topographical patterns of TC18 specimens under different UAM conditions (cutting speeds, feeds per tooth, cutting depths, and ultrasonic vibration amplitudes) were examined. The differences between ordinary milling and UAM in terms of machining performance were compared. Using UAM, numerous characteristics (including variable cutting thickness in the cutting area, variable cutting front angles of the tool, and the lifting of the cuttings by the tool) were optimized, reducing the average cutting force in all directions, lowering the cutting temperature, increasing the surface residual compressive stress, and significantly improving the surface morphology. Finally, fish scale bionic microtextures with clear, uniform, and regular patterns were formed on the machined surface. High-frequency vibration can improve material removal convenience, thus reducing surface roughness. The introduction of longitudinal ultrasonic vibration to the end milling process can overcome the limitations of traditional processing. The optimal combination of UAM parameters for titanium alloy machining was determined through the end milling orthogonal test with compound ultrasonic vibration, which significantly improved the surface quality of TC18 workpieces. This study provides insightful reference data for subsequent machining process optimization.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061111
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1112: A New Hybrid Stepper Motor, Compliant
Piezoelectric Micro-Tweezer for Extended Stroke
Authors: Ioan Alexandru Ivan, Dan Cristian Noveanu, Valentin Ion Gurgu, Veronica Despa, Simona Noveanu
First page: 1112
Abstract: The revolutionary economic potential of micro and nanotechnology is already recognized. Micro and nano-scale technologies that use electrical, magnetic, optical, mechanical, and thermal phenomena separately or in combination are either already in the industrial phase or approaching it. The products of micro and nanotechnology are made of small quantities of material but have high functionality and added value. This paper presents such a product: a system with micro-tweezers for biomedical applications—a micromanipulator with optimized constructive characteristics, including optimal centering, consumption, and minimum size, for handling micro-particles and constructive micro components. The advantage of the proposed structure consists mainly in obtaining a large working area combined with a good working resolution due to the double actuation principle: electromagnetic and piezoelectric.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061112
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1113: A Cotton Fabric Composite with Light
Mineral Oil and Magnetite Nanoparticles: Effects of a Magnetic Field and
Uniform Compressions on Electrical Conductivity
Authors: Gabriela-Eugenia Iacobescu, Madalin Bunoiu, Ioan Bica, Paula Sfirloaga, Larisa-Marina-Elisabeth Chirigiu
First page: 1113
Abstract: Over the past few decades, tactile sensors have become an emerging field of research with direct applications in the area of biomedical engineering. New types of tactile sensors, called magneto-tactile sensors, have recently been developed. The aim of our work was to create a low-cost composite whose electrical conductivity depends on mechanical compressions that can be finely tuned using a magnetic field for magneto-tactile sensor fabrication. For this purpose, 100% cotton fabric was impregnated with a magnetic liquid (EFH-1 type) based on light mineral oil and magnetite particles. The new composite was used to manufacture an electrical device. With the experimental installation described in this study, we measured the electrical resistance of an electrical device placed in a magnetic field in the absence or presence of uniform compressions. The effect of uniform compressions and the magnetic field was the induction of mechanical–magneto–elastic deformations and, as a result, variations in electrical conductivity. In a magnetic field with a flux density of 390 mT, in the absence of mechanical compression forces, a magnetic pressure of 5.36 kPa was generated, and the electrical conductivity increased by 400% compared to that of the composite in the absence of a magnetic field. Upon increasing the compression force to 9 N, in the absence of a magnetic field, the electrical conductivity increased by about 300% compared to that of the device in the absence of compression forces and a magnetic field. In the presence of a magnetic flux density of 390 mT, and when the compression force increased from 3 N to 9 N, the electrical conductivity increased by 2800%. These results suggest the new composite is a promising material for magneto-tactile sensors.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061113
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1114: Toward the Real-Time and Rapid
Quantification of Bacterial Cells Utilizing a Quartz Tuning Fork Sensor
Authors: Abeer Alshammari, Sabaa T. Abdulmawla, Reem Alsaigh, Khaloud Mohammed Alarjani, Norah Salim Aldosari, Muthumareeswaran Muthuramamoorthy, Abdulaziz K. Assaifan, Hamad Albrithen, Khalid E. Alzahrani, Abdullah N. Alodhayb
First page: 1114
Abstract: The quantitative evaluation of bacterial populations is required in many studies, particularly in the field of microbiology. The current techniques can be time-consuming and require a large volume of samples and trained laboratory personnel. In this regard, on-site, easy-to-use, and direct detection techniques are desirable. In this study, a quartz tuning fork (QTF) was investigated for the real-time detection of E. coli in different media, as well as the ability to determine the bacterial state and correlate the QTF parameters to the bacterial concentration. QTFs that are commercially available can also be used as sensitive sensors of viscosity and density by determining the QTFs’ damping and resonance frequency. As a result, the influence of viscous biofilm adhered to its surface should be detectable. First, the response of a QTF to different media without E. coli was investigated, and Luria–Bertani broth (LB) growth medium caused the largest change in frequency. Then, the QTF was tested against different concentrations of E. coli (i.e., 102–105 colony-forming units per milliliter (CFU/mL)). As the E. coli concentration increased, the frequency decreased from 32.836 to 32.242 kHz. Similarly, the quality factor decreased with the increasing E. coli concentration. With a coefficient (R) of 0.955, a linear correlation between the QTF parameters and bacterial concentration was established with a 26 CFU/mL detection limit. Furthermore, a considerable change in frequency was observed against live and dead cells in different media. These observations demonstrate the ability of QTFs to distinguish between different bacterial states. QTFs allow real-time, rapid, low-cost, and non-destructive microbial enumeration testing that requires only a small volume of liquid sample.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061114
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1115: Study of Rotation Speed Curve
Optimization under the Three-Body Coupling Grinding Mode
Authors: Wei Yu, Binghai Lyu, Qianfa Deng, Chengwu Wang
First page: 1115
Abstract: The three-body coupling grinding mode of a ball ensures the batch diameter variation and batch consistency of precision ball machining based on the principle of ball forming, resulting in a structure that is simply and feasibly controllable. The change in the rotation angle can be jointly determined using the fixed load of the upper grinding disc and the rotation speed coordination of the inner and outer discs of the lower grinding disc. Related to this, the rotation speed is an important index to guarantee grinding uniformity. To ensure the quality of three-body coupling grinding, this study aims to establish the best mathematical control model of the rotation speed curve of the inner and outer discs in the lower grinding disc. Specifically, it includes two aspects. First, the optimization of the rotation speed curve was mainly studied, and the machining process was simulated with three speed curve combinations: 1, 2, and 3. By analyzing the evaluation index of ball grinding uniformity, the results revealed that the third speed curve combination had the best grinding uniformity, and the three speed curve combinations were optimized on the basis of the traditional triangular wave speed curve. Furthermore, the obtained double trapezoidal speed curve combination not only achieved the traditionally verified stability performance but also overcame the shortcomings of the other speed curves. The mathematical model established in this way was equipped with a grinding control system, which improved the fine control ability of the rotation angle state of the ball blank under the three-body coupling grinding mode. It also obtained the best grinding uniformity and sphericity and laid a theoretical foundation for achieving a grinding effect that was close to the ideal circumstance during mass production. Second, via theoretical comparison and analysis, it was determined that the ball shape and sphericity deviation (SPD) were more accurate than the standard deviation (STD) of the two-dimensional trajectory point distribution. The SPD evaluation method was also investigated via the optimization analysis of the rotation speed curve by means of the ADAMAS simulation. The obtained results coincided with the STD evaluation trend, thus laying a preliminary foundation for subsequent applications.
Citation: Micromachines
PubDate: 2023-05-25
DOI: 10.3390/mi14061115
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1116: Three-Dimensional Modeling of the
Optical Switch Based on Guided-Mode Resonances in Photonic Crystals
Authors: Atiq Ur Rehman, Yousuf Khan, Muhammad Irfan, Shahzaib Choudri, Svetlana N. Khonina, Nikolay L. Kazanskiy, Muhammad A. Butt
First page: 1116
Abstract: Optical switching is an essential part of photonic integrated circuits and the focus of research at the moment. In this research, an optical switch design working on the phenomenon of guided-mode resonances in a 3D photonic-crystal-based structure is reported. The optical-switching mechanism is studied in a dielectric slab-waveguide-based structure operating in the near-infrared range in a telecom window of 1.55 µm. The mechanism is investigated via the interference of two signals, i.e., the data signal and the control signal. The data signal is coupled into the optical structure and filtered utilizing guided-mode resonance, whereas the control signal is index-guided in the optical structure. The amplification or de-amplification of the data signal is controlled by tuning the spectral properties of the optical sources and structural parameters of the device. The parameters are optimized first using a single-cell model with periodic boundary conditions and later in a finite 3D-FDTD model of the device. The numerical design is computed in an open-source Finite Difference Time Domain simulation platform. Optical amplification in the range of 13.75% is achieved in the data signal with a decrease in the linewidth up to 0.0079 µm, achieving a quality factor of 114.58. The proposed device presents great potential in the field of photonic integrated circuits, biomedical technology, and programmable photonics.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061116
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1117: A Compact Piezo-Inertia Actuator
Utilizing the Double-Rocker Flexure Hinge Mechanism
Authors: Pingping Sun, Chenglong Lei, Chuannan Ge, Yunjun Guo, Xingxing Zhu
First page: 1117
Abstract: With a simple structure and control method, the piezo-inertia actuator is a preferred embodiment in the field of microprecision industry. However, most of the previously reported actuators are unable to achieve a high speed, high resolution, and low deviation between positive and reverse velocities at the same time. To achieve a high speed, high resolution, and low deviation, in this paper we present a compact piezo-inertia actuator with a double rocker-type flexure hinge mechanism. The structure and operating principle are discussed in detail. To study the load capacity, voltage characteristics, and frequency characteristics of the actuator, we made a prototype and conducted a series of experiment. The results indicate good linearity in both positive and negative output displacements. The maximum positive and negative velocities are about 10.63 mm/s and 10.12 mm/s, respectively, and the corresponding speed deviation is 4.9%. The positive and negative positioning resolutions are 42.5 nm and 52.5 nm, respectively. In addition, the maximum output force is 220 g. These results show that the designed actuator has a minor speed deviation and good output characteristics.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061117
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1118: A Microfluidic Device for Tobacco
Ringspot Virus Detection by Electrochemical Impedance Spectroscopy
Authors: Xiaoxing Weng, Chen Li, Changqing Chen, Gang Wang, Chenghao Xia, Lianyou Zheng
First page: 1118
Abstract: Aiming at the problem of how to achieve the rapid detection of pathogenic microorganisms, this paper takes tobacco ringspot virus as the detection object, designs the impedance detection and analysis platform of tobacco ringspot virus based on microfluidic impedance method, establishes an equivalent circuit model to analyze the experimental results, and determines the optimal detection frequency of tobacco ringspot virus detection. Based on this frequency, an impedance–concentration regression model was established for the detection of tobacco ringspot virus in a tobacco ringspot virus detection device. Based on this model, a tobacco ringspot virus detection device was designed by using an AD5933 impedance detection chip. A comprehensive test study was carried out on the developed tobacco ringspot virus detection device through various testing methods, which verified the feasibility of the tobacco ringspot virus detection device and provided technical support for the field detection of pathogenic microorganisms.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061118
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1119: A Lightweight Method for Detecting IC
Wire Bonding Defects in X-ray Images
Authors: Daohua Zhan, Jian Lin, Xiuding Yang, Renbin Huang, Kunran Yi, Maoling Liu, Hehui Zheng, Jingang Xiong, Nian Cai, Han Wang, Baojun Qiu
First page: 1119
Abstract: Integrated circuit (IC) X-ray wire bonding image inspections are crucial for ensuring the quality of packaged products. However, detecting defects in IC chips can be challenging due to the slow defect detection speed and the high energy consumption of the available models. In this paper, we propose a new convolutional neural network (CNN)-based framework for detecting wire bonding defects in IC chip images. This framework incorporates a Spatial Convolution Attention (SCA) module to integrate multi-scale features and assign adaptive weights to each feature source. We also designed a lightweight network, called the Light and Mobile Network (LMNet), using the SCA module to enhance the framework’s practicality in the industry. The experimental results demonstrate that the LMNet achieves a satisfactory balance between performance and consumption. Specifically, the network achieved a mean average precision (mAP50) of 99.2, with 1.5 giga floating-point operations (GFLOPs) and 108.7 frames per second (FPS), in wire bonding defect detection.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061119
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1120: Arc Discharge System for
Micromachining of Helical Fiber
Authors: Jian Wang, Chao Ma, Shaochen Duan, Donghui Wang, Libo Yuan
First page: 1120
Abstract: This article developed a micromachining system of arcing helical fiber with four electrodes to address the issues with conventional approaches to processing helical fibers, which have several uses. The technique may be utilized to create several types of helical fibers. First, the simulation demonstrates that the four-electrode arc’s constant-temperature heating area is larger than the two-electrode arc’s size. A large constant-temperature heating area is not only beneficial to the stress release of fiber, but also reduces the influence of fiber vibration and reduces the difficulty of device debugging. Then, a variety of helical fibers with various pitches were processed using the system presented in this research. By using a microscope, it can be observed that the cladding and core edges of the helical fiber are constantly smooth and the central core is tiny and off-axis, both of which are favorable for the propagation of optical waveguides. A low off-axis has been shown to minimize optical loss through modeling of energy coupling in spiral multi-core optical fibers. The transmission spectrum findings indicated that the device’s insertion loss and transmission spectrum fluctuation were both minimal for four different types of multi-core spiral long-period fiber gratings with intermediate cores. These prove that the spiral fibers prepared by this system have excellent quality.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061120
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1121: Simulation Optimization of AlGaN/GaN
SBD with Field Plate Structures and Recessed Anode
Authors: Tao Xu, Ziqi Tang, Ziyou Zhou, Bing Zhou
First page: 1121
Abstract: This study investigated several AlGaN/GaN Schottky Barrier Diodes (SBDs) with different designs to achieve device optimization. First, the optimal electrode spacing, etching depth, and field plate size of the devices were measured using Technology Computer-Aided Design (TCAD) software by Silvaco, and analysis of the electrical behavior of the device was based on the simulation results, and several AlGaN/GaN SBD chips were designed and prepared. The experimental results revealed that the recessed anode can increase the forward current and reduce the on-resistance. An etched depth of 30 nm could obtain a turn-on voltage of 0.75 V and a forward current density of 216 mA/mm. A breakdown voltage of 1043 V and a power figure of merit (FOM) value of 572.6 MW/cm2 was obtained with a 3 μm field plate. Experiments and simulations confirmed that the recessed anode and field plate structure could increase the breakdown voltage and forward current and improve the FOM value, resulting in higher electrical performance and a wider range of application scenarios.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061121
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1122: Bioaffinity Nanoprobes for Foodborne
Pathogen Sensing
Authors: Tracy Ann Bruce-Tagoe, Michael K. Danquah
First page: 1122
Abstract: Bioaffinity nanoprobes are a type of biosensor that utilize the specific binding properties of biological molecules, such as antibodies, enzymes, and nucleic acids, for the detection of foodborne pathogens. These probes serve as nanosensors and can provide highly specific and sensitive detection of pathogens in food samples, making them an attractive option for food safety testing. The advantages of bioaffinity nanoprobes include their ability to detect low levels of pathogens, rapid analysis time, and cost-effectiveness. However, limitations include the need for specialized equipment and the potential for cross-reactivity with other biological molecules. Current research efforts focus on optimizing the performance of bioaffinity probes and expanding their application in the food industry. This article discusses relevant analytical methods, such as surface plasmon resonance (SPR) analysis, Fluorescence Resonance Energy Transfer (FRET) measurements, circular dichroism, and flow cytometry, that are used to evaluate the efficacy of bioaffinity nanoprobes. Additionally, it discusses advances in the development and application of biosensors in monitoring foodborne pathogens.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061122
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1123: Stability Study of Multi-Level
Grayscales Based on Driving Waveforms for Electrowetting Displays
Authors: Wanzhen Xu, Zichuan Yi, Zhengxing Long, Hu Zhang, Jiaquan Jiang, Liming Liu, Feng Chi, Ding Tan, Huan Wang
First page: 1123
Abstract: Electrowetting Display (EWD) is a new reflective display with an outstanding performance of color video playback. However, some problems still exist and affect its performance. For instance, oil backflow, oil splitting, and charge trapping phenomena may occur during the driving process of EWDs, which would decrease its stability of multi-level grayscales. Therefore, an efficient driving waveform was proposed to solve these disadvantages. It consisted of a driving stage and a stabilizing stage. First, an exponential function waveform was used in the driving stage for driving the EWDs quickly. Then, an alternating current (AC) pulse signal waveform was used in the stabilizing stage to release the trapped positive charges of the insulating layer to improve display stability. A set of four level grayscale driving waveforms were designed by using the proposed method, and it was used in comparative experiments. The experiments showed that the proposed driving waveform could mitigate oil backflow and splitting effects. Compared to a traditional driving waveform, the luminance stability was increased by 8.9%, 5.9%, 10.9%, and 11.6% for the four level grayscales after 12 s, respectively.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061123
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1124: Analysis of the Influence of the
Authors: Zhixiang Chen, Shunkai Han, Ming Feng, Xianglei Zhang
First page: 1124
Abstract: Ultra-thin sapphire wafer processing is receiving increasing attention in the LED substrate industry. In the cascade clamping method, the motion state of the wafer determines the uniformity of material removal, while the motion state of the wafer is related to its friction coefficient in the biplane processing system, but there is little relevant literature discussing the relationship between the motion state of wafer and friction coefficient. In this study, an analytical model of the motion state of sapphire wafers in the layer-stacked clamping process based on the frictional moment is established, the effect of each friction coefficient on its motion is discussed, the base plate of different materials and different roughness are experimentally studied, the layer-stacked clamping fixture is prepared in this way, and finally the failure form of the limiting tab is analyzed experimentally. The theoretical analysis shows that the sapphire wafer is mainly driven by the polishing plate, while the base plate is mainly driven by the holder, and the rotation speed of the two is not the same; the material of the base plate of the layer-stacked clamping fixture is stainless steel, the material of the limiter is glass fiber plate, and the main form of failure of the limiter is to be cut by the edge of the sapphire wafer and damage the material structure.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061124
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1125: Exploring the Potential of
Flow-Induced Vibration Energy Harvesting Using a Corrugated Hyperstructure
Bluff Body
Authors: Yikai Yuan, Hai Wang, Chunlai Yang, Hang Sun, Ye Tang, Zihao Zhang
First page: 1125
Abstract: Fluid-induced vibration is a common phenomenon in fluid–structure interaction. A flow-induced vibrational energy harvester based on a corrugated hyperstructure bluff body which can improve energy collection efficiency under low wind speeds is proposed in this paper. CFD simulation of the proposed energy harvester was carried out with COMSOL Multiphysics. The flow field around the harvester and the output voltage in different flow velocities is discussed and validated with experiments. Simulation results show that the proposed harvester has an improved harvesting efficiency and higher output voltage. Experimental results show that the output voltage amplitude of the harvester increased by 189% under 2 m/s wind speed.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061125
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1126: A Review of Intelligent Assembly
Technology of Small Electronic Equipment
Authors: Wei Tian, Yifan Ding, Xiaodong Du, Ke Li, Zihang Wang, Changrui Wang, Chao Deng, Wenhe Liao
First page: 1126
Abstract: Electronic equipment, including phased array radars, satellites, high-performance computers, etc., has been widely used in military and civilian fields. Its importance and significance are self-evident. Electronic equipment has many small components, various functions, and complex structures, making assembly an essential step in the manufacturing process of electronic equipment. In recent years, the traditional assembly methods have had difficulty meeting the increasingly complex assembly needs of military and civilian electronic equipment. With the rapid development of Industry 4.0, emerging intelligent assembly technology is replacing the original “semi-automatic” assembly technology. Aiming at the assembly requirements of small electronic equipment, we first evaluate the existing problems and technical difficulties. Then, we analyze the intelligent assembly technology of electronic equipment from three aspects: visual positioning, path and trajectory planning, and force–position coordination control technology. Further, we describe and summarize the research status and the application of the technology and discuss possible future research directions in the intelligent assembly technology of small electronic equipment.
Citation: Micromachines
PubDate: 2023-05-26
DOI: 10.3390/mi14061126
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1127: Comparative Analysis of Perovskite
Solar Cells for Obtaining a Higher Efficiency Using a Numerical Approach
Authors: Khaled Hussein Mahmoud, Abdullah Saad Alsubaie, Abdul Hakeem Anwer, Mohd Zahid Ansari
First page: 1127
Abstract: Perovskite materials have gained considerable attention in recent years for their potential to improve the efficiency of solar cells. This study focuses on optimizing the efficiency of perovskite solar cells (PSCs) by investigating the thickness of the methylammonium-free absorber layer in the device structure. In the study we used a SCAPS-1D simulator to analyze the performance of MASnI3 and CsPbI3-based PSCs under AM1.5 illumination. The simulation involved using Spiro-OMeTAD as a hole transport layer (HTL) and ZnO as the electron transport layer (ETL) in the PSC structure. The results indicate that optimizing the thickness of the absorber layer can significantly increase the efficiency of PSCs. The precise bandgap values of the materials were set to 1.3 eV and 1.7 eV. In the study we also investigated the maximum thicknesses of the HTL, MASnI3, CsPbI3, and the ETL for the device structures, which were determined to be 100 nm, 600 nm, 800 nm, and 100 nm, respectively. The improvement techniques used in this study resulted in a high power-conversion efficiency (PCE) of 22.86% due to a higher value of VOC for the CsPbI3-based PSC structure. The findings of this study demonstrate the potential of perovskite materials as absorber layers in solar cells. It also provides insights into improving the efficiency of PSCs, which is crucial for advancing the development of cost-effective and efficient solar energy systems. Overall, this study provides valuable information for the future development of more efficient solar cell technologies.
Citation: Micromachines
PubDate: 2023-05-27
DOI: 10.3390/mi14061127
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1128: A Method of Water COD Retrieval Based
on 1D CNN and 2D Gabor Transform for Absorption–Fluorescence Spectra
Authors: Meng Xia, Ruifang Yang, Nanjing Zhao, Xiaowei Chen, Ming Dong, Jingsong Chen
First page: 1128
Abstract: Chemical Oxygen Demand (COD) is one of the indicators of organic pollution in water bodies. The rapid and accurate detection of COD is of great significance to environmental protection. To address the problem of COD retrieval errors in the absorption spectrum method for fluorescent organic matter solutions, a rapid synchronous COD retrieval method for the absorption–fluorescence spectrum is proposed. Based on a one-dimensional convolutional neural network and 2D Gabor transform, an absorption–fluorescence spectrum fusion neural network algorithm is developed to improve the accuracy of water COD retrieval. Results show that the RRMSEP of the absorption–fluorescence COD retrieval method is 0.32% in amino acid aqueous solution, which is 84% lower than that of the single absorption spectrum method. The accuracy of COD retrieval is 98%, which is 15.3% higher than that of the single absorption spectrum method. The test results on the actual sampled water spectral dataset demonstrate that the fusion network outperformed the absorption spectrum CNN network in measuring COD accuracy, with the RRMSEP improving from 5.09% to 1.15%.
Citation: Micromachines
PubDate: 2023-05-27
DOI: 10.3390/mi14061128
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1129: High-Speed Hardware Architecture Based
on Error Detection for KECCAK
Authors: Hassen Mestiri, Imen Barraj
First page: 1129
Abstract: The hash function KECCAK integrity algorithm is implemented in cryptographic systems to provide high security for any circuit requiring integrity and protect the transmitted data. Fault attacks, which can extricate confidential data, are one of the most effective physical attacks against KECCAK hardware. Several KECCAK fault detection systems have been proposed to counteract fault attacks. The present research proposes a modified KECCAK architecture and scrambling algorithm to protect against fault injection attacks. Thus, the KECCAK round is modified so that it consists of two parts with input and pipeline registers. The scheme is independent of the KECCAK design. Iterative and pipeline designs are both protected by it. To test the resilience of the suggested detection system approach fault attacks, we conduct permanent as well as transient fault attacks, and we evaluate the fault detection capabilities (99.9999% for transient faults and 99.999905% for permanent faults). The KECCAK fault detection scheme is modeled using VHDL language and implemented on an FPGA hardware board. The experimental results show that our technique effectively secures the KECCAK design. It can be carried out with little difficulty. In addition, the experimental FPGA results demonstrate the proposed KECCAK detection scheme’s low area burden, high efficiency and working frequency.
Citation: Micromachines
PubDate: 2023-05-27
DOI: 10.3390/mi14061129
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1130: Design of an Intelligent MEMS Safety
and Arming Device with a Condition Feedback Function
Authors: Kexin Wang, Tengjiang Hu, Yulong Zhao, Wei Ren, Yifei Wang
First page: 1130
Abstract: A safety and arming device with a condition feedback function has been designed in this article to improve the intelligence and safety of ignition devices. The device achieves active control and recoverability by virtue of four groups of bistable mechanisms which consist of two electrothermal actuators to drive a semi-circular barrier and a pawl. According to a specific operation sequence, the barrier is engaged by the pawl at the safety or the arming position. The four groups of bistable mechanisms are connected in parallel, and the device detects the contact resistance generated by the engagement of the barrier and pawl by the voltage division of an external resistor to determine the parallel number of the mechanism and give feedback on the device’s condition. The pawl as a safety lock can restrain the in-plane deformation of the barrier in the safety condition to improve the safety function of the device. An igniter (a NiCr bridge foil covered with different thicknesses of Al/CuO films) and boron/potassium nitrate (B/KNO3, BPN) are assembled on both sides of the S&A device to verify the safety of the barrier. The test results show that the S&A device with a safety lock can realize the safety and arming functions when the thickness of the Al/CuO film is set to 80 μm and 100 μm.
Citation: Micromachines
PubDate: 2023-05-27
DOI: 10.3390/mi14061130
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1131: Interconnection Technologies for
Flexible Electronics: Materials, Fabrications, and Applications
Authors: Ratul Kumar Baruah, Hocheon Yoo, Eun Kwang Lee
First page: 1131
Abstract: Flexible electronic devices require metal interconnects to facilitate the flow of electrical signals among the device components, ensuring its proper functionality. There are multiple factors to consider when designing metal interconnects for flexible electronics, including their conductivity, flexibility, reliability, and cost. This article provides an overview of recent endeavors to create flexible electronic devices through different metal interconnect approaches, with a focus on materials and structural aspects. Additionally, the article discusses emerging flexible applications, such as e-textiles and flexible batteries, as essential considerations.
Citation: Micromachines
PubDate: 2023-05-27
DOI: 10.3390/mi14061131
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1132: Next-Generation Reconfigurable
Nanoantennas and Polarization of Light
Authors: Tannaz Farrahi, George K. Giakos
First page: 1132
Abstract: This study is aimed at the design, calibration, and development of a near-infrared (NIR) liquid crystal multifunctional automated optical polarimeter, which is aimed at the study and characterization of the polarimetric properties of polymer optical nanofilms. The characterization of these novel nanophotonic structures has been achieved, in terms of Mueller matrix and Stokes parameter analyses. The nanophotonic structures of this study consisted of (a) a matrix consisting of two different polymer domains, namely polybutadiene (PB) and polystyrene (PS), functionalized with gold nanoparticles; (b) cast and annealed Poly (styrene-b-methyl methacrylate) (PS-PMMA) diblock copolymers; (c) a matrix of a block copolymer (BCP) domain, PS-b-PMMA or Poly (styrene-block-methy methacrylate), functionalized with gold nanoparticles; and (d) different thicknesses of PS-b-P2VP diblock copolymer functionalized with gold nanoparticles. In all cases, backscattered infrared light was studied and related to the polarization figures-of-merit (FOM). The outcome of this study indicates that functionalized polymer nanomaterials, depending upon their structure and composition, exhibit promising optical characteristics, modulating and manipulating the polarimetric properties of light. The fabrication of technologically useful, tunable, conjugated polymer blends with an optimized refractive index, shape, size, spatial orientation, and arrangement would lead to the development of new nanoantennas and metasurfaces.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061132
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1133: Microfluidic Distillation System for
Separation of Propionic Acid in Foods
Authors: Song-Yu Lu, Chan-Chiung Liu, Kuan-Hsun Huang, Cheng-Xue Yu, Lung-Ming Fu
First page: 1133
Abstract: A microfluidic distillation system is proposed to facilitate the separation and subsequent determination of propionic acid (PA) in foods. The system comprises two main components: (1) a polymethyl methacrylate (PMMA) micro-distillation chip incorporating a micro-evaporator chamber, a sample reservoir, and a serpentine micro-condensation channel; and (2) and a DC-powered distillation module with built-in heating and cooling functions. In the distillation process, homogenized PA sample and de-ionized water are injected into the sample reservoir and micro-evaporator chamber, respectively, and the chip is then mounted on a side of the distillation module. The de-ionized water is heated by the distillation module, and the steam flows from the evaporation chamber to the sample reservoir, where it prompts the formation of PA vapor. The vapor flows through the serpentine microchannel and is condensed under the cooling effects of the distillation module to produce a PA extract solution. A small quantity of the extract is transferred to a macroscale HPLC and photodiode array (PDA) detector system, where the PA concentration is determined using a chromatographic method. The experimental results show that the microfluidic distillation system achieves a distillation (separation) efficiency of around 97% after 15 min. Moreover, in tests performed using 10 commercial baked food samples, the system achieves a limit of detection of 50 mg/L and a limit of quantitation of 96 mg/L, respectively. The practical feasibility of the proposed system is thus confirmed.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061133
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1134: Connection of ssDNA to Silicon
Substrate Based on a Mechano–Chemical Method
Authors: Liqiu Shi, Feng Yu, Mingming Ding, Zhouming Hang, Yan Feng, Aifang Yan, Hongji Dong
First page: 1134
Abstract: A novel fabrication process to connect single-stranded DNA (ssDNA)to a silicon substrate based on a mechano–chemical method is proposed. In this method, the single crystal silicon substrate was mechanically scribed in a diazonium solution of benzoic acid using a diamond tip which formed silicon free radicals. These combined covalently with organic molecules of diazonium benzoic acid contained in the solution to form self-assembled films (SAMs). The SAMs were characterized and analyzed by AFM, X-ray photoelectron spectroscopy and infrared spectroscopy. The results showed that the self-assembled films were covalently connected to the silicon substrate by Si–C. In this way, a nano-level benzoic acid coupling layer was self-assembled on the scribed area of the silicon substrate. The ssDNA was further covalently connected to the silicon surface by the coupling layer. Fluorescence microscopy showed that ssDNA had been connected, and the influence of ssDNA concentration on the fixation effect was studied. The fluorescence brightness gradually increased with the gradual increase in ssDNA concentration from 5 μmol/L to 15 μmol/L, indicating that the fixed amount of ssDNA increased. However, when the concentration of ssDNA increased from 15 μmol/L to 20 μmol/L, the detected fluorescence brightness decreased, indicating that the hybridization amount decreased. The reason may be related to the spatial arrangement of DNA and the electrostatic repulsion between DNA molecules. It was also found that ssDNA junctions on the silicon surface were not very uniform, which was related to many factors, such as the inhomogeneity of the self-assembled coupling layer, the multi-step experimental operation and the pH value of the fixation solution.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061134
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1135: Field Effect Transistor with
Nanoporous Gold Electrode
Authors: Ezzat G. Bakhoum, Cheng Zhang
First page: 1135
Abstract: Nanoporous gold (NPG) has excellent catalytic activity and has been used in the recent literature on this issue as a sensor in various electrochemical and bioelectrochemical reactions. This paper reports on a new type of metal–oxide–semiconductor field-effect transistor (MOSFET) that utilizes NPG as a gate electrode. Both n-channel and p-channel MOSFETs with NPG gate electrodes have been fabricated. The MOSFETs can be used as sensors and the results of two experiments are reported: the detection of glucose and the detection of carbon monoxide. A detailed comparison of the performance of the new MOSFET to that of the older generation of MOSFETs fitted with zinc oxide gate electrodes is given.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061135
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1136: Pure- and
Pseudo-Lateral-Field-Excitation Characteristics of Relaxor Ferroelectric
Single Crystal PMN-PT
Authors: Fei Sun, Tingfeng Ma, Pengfei Kang, Yuming Yao, Ning Gan, Lili Yuan, Wenhui Hu, Iren Kuznetsova, Ilya Nedospasov
First page: 1136
Abstract: The relaxor ferroelectric single crystal (1−x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) has high piezoelectric constants, and thus has a good application prospect in the field of highly sensitive piezoelectric sensors. In this paper, for relaxor ferroelectric single crystal PMN-PT, the bulk acoustic wave characteristics on pure- and pseudo-lateral-field-excitation (pure- and pseudo-LFE) modes are investigated. LFE piezoelectric coupling coefficients and acoustic wave phase velocities for PMN-PT crystals in different cuts and electric field directions are calculated. On this basis, the optimal cuts of pure-LFE and pseudo-LFE modes of relaxor ferroelectric single crystal PMN-PT are obtained, namely, (zxt)45° and (zxtl)90°/90°, respectively. Finally, finite element simulations are carried out to verify the cuts of pure-LFE and pseudo-LFE modes. The simulation results show that the PMN-PT acoustic wave devices in pure-LFE mode have good energy-trapping effects. For PMN-PT acoustic wave devices in pseudo-LFE mode, when the device is in air, no obvious energy-trapping emerges; when the water (as a virtual electrode) is added to the surface of the crystal plate, an obvious resonance peak and the energy-trapping effect appears. Therefore, the PMN-PT pure-LFE device is suitable for gas-phase detections. While the PMN-PT pseudo-LFE device is suitable for liquid-phase detections. The above results verify the correctness of the cuts of the two modes. The research results provide an important basis for the development of highly sensitive LFE piezoelectric sensors based on relaxor ferroelectric single crystal PMN-PT.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061136
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1137: Microfluidic Study of Enhanced Oil
Recovery during Flooding with Polyacrylamide Polymer Solutions
Authors: Maxim Pryazhnikov, Andrey Pryazhnikov, Angelica Skorobogatova, Andrey Minakov, Yulia Ivleva
First page: 1137
Abstract: A series of experiments have been carried out on the flooding of microfluidic chips simulating a homogeneous porous structure with various displacement fluids. Water and polyacrylamide polymer solutions were used as displacement fluids. Three different polyacrylamides with different properties are considered. The results of a microfluidic study of polymer flooding showed that the displacement efficiency increases significantly with increasing polymer concentration. Thus, when using a 0.1% polymer solution of polyacrylamide grade 2540, a 23% increase in the oil displacement efficiency was obtained compared to water. The study of the effect of various polymers on the efficiency of oil displacement showed that the maximum efficiency of oil displacement, other things being equal, can be achieved using polyacrylamide grade 2540, which has the highest charge density among those considered. Thus, when using polymer 2515 with a charge density of 10%, the oil displacement efficiency increased by 12.5% compared to water, while when using polymer 2540 with a charge density of 30%, the oil displacement efficiency increased by 23.6%.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061137
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1138: Disturbance Characteristics of 1T DRAM
Arrays Consisting of Feedback Field-Effect Transistors
Authors: Juhee Jeon, Kyoungah Cho, Sangsig Kim
First page: 1138
Abstract: Challenges in scaling dynamic random-access memory (DRAM) have become a crucial problem for implementing high-density and high-performance memory devices. Feedback field-effect transistors (FBFETs) have great potential to overcome the scaling challenges because of their one-transistor (1T) memory behaviors with a capacitorless structure. Although FBFETs have been studied as 1T memory devices, the reliability in an array must be evaluated. Cell reliability is closely related to device malfunction. Hence, in this study, we propose a 1T DRAM consisting of an FBFET with a p+–n–p–n+ silicon nanowire and investigate the memory operation and disturbance in a 3 × 3 array structure through mixed-mode simulations. The 1T DRAM exhibits a write speed of 2.5 ns, a sense margin of 90 μA/μm, and a retention time of approximately 1 s. Moreover, the energy consumption is 5.0 × 10−15 J/bit for the write ‘1’ operation and 0 J/bit for the hold operation. Furthermore, the 1T DRAM shows nondestructive read characteristics, reliable 3 × 3 array operation without any write disturbance, and feasibility in a massive array with an access time of a few nanoseconds.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061138
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1139: A Double-Layer Dual-Polarized Huygens
Metasurface and Its Meta-Lens Antenna Applications
Authors: Shuo Cao, Jianhe Zhou, Ruxue Li, Chunhua Xue
First page: 1139
Abstract: In this paper, a dual-polarized Huygens unit is proposed, which has a double-layer metallic pattern etched on both sides of one dielectric substrate. Induced magnetism enables the structure to support Huygens’ resonance, thus obtaining nearly complete available transmission phase coverage. By optimizing the structural parameters, a better transmission performance can be achieved. When the Huygens metasurface was used for the design of a meta-lens, good radiation performance was exhibited, with a maximum gain of 31.15 dBi at 28 GHz, an aperture efficiency of 42.7% and a 3 dB gain bandwidth of 26.4 GHz to 30 GHz (12.86%). Due to its excellent radiation performance and very simple fabrication, this Huygens meta-lens has important applications in millimeter-wave communication systems.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061139
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1140: Development of a Novel Piezoelectric
Actuator Based on Stick–Slip Principle by Using Asymmetric
Constraint
Authors: Liang Wang, Heran Wang, Junxiang Jiang, Tianwen Luo
First page: 1140
Abstract: In this work, a novel piezoelectric actuator based on the stick–slip principle is proposed. The actuator is constrained by an asymmetric constraint approach; the driving foot produces lateral and longitudinal coupling displacements when the piezo stack is extended. The lateral displacement is used to drive the slider and the longitudinal displacement is used to compress the slider. The stator part of the proposed actuator is illustrated and designed by simulation. The operating principle of the proposed actuator is described in detail. The feasibility of the proposed actuator is verified by theoretical analysis and finite element simulation. A prototype is fabricated and some experiments are carried out to study the proposed actuator’s performance. The experimental results show that the maximum output speed of the actuator is 3680 μm/s when the locking force is 1 N under the voltage of 100 V and frequency of 780 Hz. The maximum output force is 3.1 N when the locking force is 3 N. The displacement resolution of the prototype is measured as 60 nm under the voltage of 15.8 V, frequency of 780 Hz and locking force of 1 N.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061140
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1141: Exploiting Interfacial Effects between
Collapsing Bubbles and Nanocarbon/TiN Substrates for the Green Synthesis
of Self-Organized Noble Metal and Nanoalloy Nanoparticles
Authors: Mohammed Es-Souni
First page: 1141
Abstract: Noble metal nanoparticles and multi-materials thereof are processed on a substrate from aqueous solutions of the metallic ions, precluding any chemical additives/catalysts. The methods reported here take advantage of interactions between collapsing bubbles and the substrate that result in the generation of reducing radicals at the substrate surface and leading to the reduction of the metal ions on those sites, followed by nucleation and growth. Two selected substrates where these phenomena take place are nanocarbon and TiN. By either using ultrasonic radiation of the substrate in ionic solution or quenching the substrate in a solution from temperatures above the Leidenfrost temperature, a high density of nanoparticles of Au, Au/Pt, Au/Pd and Au/Pd/Pt are synthesized on the substrate surface. The sites where the reducing radicals are generated determine the self-assembly of the nanoparticles. The methods yield highly adherent surface films and nanoparticles; they are materials efficient and cost effective because only the surface is modified with costly materials. The formation mechanisms of these green multi-material NPs are described. Outstanding electrocatalytic performances in acidic solutions of methanol and formic acid are demonstrated.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061141
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1142: Research on Optical Metrology for
Complex Optical Surfaces with Focal Plane Wavefront Sensing
Authors: Xinxue Ma, Jianli Wang, Bin Wang, Xinyue Liu, Yuqiang Chen
First page: 1142
Abstract: Complex optical elements have the advantages of improving image quality and optical performance and expanding the field of view. Therefore, it is widely used in X-ray scientific devices, adaptive optical elements, high-energy laser systems, and other fields and is a hot research direction in precision optics. Especially for precision machining, there is a greater need for high-precision testing technology. However, how to measure complex surfaces efficiently and accurately is still an important research topic in optical metrology technology. In order to verify the ability of optical metrology for complex optical surfaces with wavefront sensing based on image information of the focal plane, some experiment platforms in different types of optical surfaces were set up. In order to validate the feasibility and validity of wavefront-sensing technology based on image information of focal planes, a large number of repetitive experiments were carried out. The measurement results with wavefront sensing based on image information of the focal plane were compared with the measurement results with the ZYGO interferometer. The experimental results demonstrate that good agreement is obtained among the error distribution, PV value, and RMS value of the ZYGO interferometer, which shows the feasibility and validity of wavefront sensing based on image information of focal plane technology in optical metrology for the complex optical surface.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061142
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1143: Surface Quality and Material Removal
Rate in Fabricating Microtexture on Tungsten Carbide via Femtosecond Laser
Authors: Guangxian Li, Xuanang Li, Guichao He, Ruiguang Fan, Feiyuan Li, Songlin Ding
First page: 1143
Abstract: Tungsten carbide is currently the most widely used tool material for machining difficult-to-machine materials, such as titanium alloys and nickel-based super alloys. In order to improve the performance of tungsten carbide tools, surface microtexturing, a novel technology that can effectively reduce cutting forces and cutting temperatures and improve wear resistance, has been applied in metalworking processes. However, when fabricating the micro-textures such as micro-grooves or micro-holes on tool surfaces, the significant decrease in material removal rate is a major obstacle. In this study, a straight-groove-array microtexture was fabricated on the surface of tungsten carbide tools via a femtosecond laser with different machining parameters including laser power, laser frequency, and scanning speed. The material removal rate, surface roughness, and the laser-induced periodic surface structure were analyzed. It was found that the increase in the scanning speed decreased the material removal rate, whereas increasing the laser power and laser frequency had the opposite effects on the material removal rate. The laser-induced periodic surface structure was found to have a significant influence on the material removal rate, and the destruction of the laser-induced periodic surface structure was the reason for the reduction in the material removal rate. The results of the study revealed the fundamental mechanisms of the efficient machining method for the fabrication of microtextures on ultrahard materials with an ultrashort laser.
Citation: Micromachines
PubDate: 2023-05-28
DOI: 10.3390/mi14061143
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1144: Switching Regulator Based on a
Non-Inverting Step-Down/Up DC–DC Converter for Lithium-Ion Battery
Applications
Authors: Juan Antonio Villanueva-Loredo, Ma Guadalupe Ortiz-Lopez, Jesus Leyva-Ramos, Luis Humberto Diaz-Saldierna
First page: 1144
Abstract: A regulator based on a converter with step-down/up characteristics is discussed in this paper, which is suitable for processing energy from a lithium-ion battery pack, where the voltage fluctuates from above or below the nominal value. However, this regulator can also be used for applications such as unregulated line rectifiers and renewable energy sources, among others. The converter consists of a non-cascaded interconnection of boost and buck–boost converters such that part of the input energy is transferred directly to the output without reprocessing. Furthermore, it has a non-pulsating input current and a non-inverting output voltage, making it easier to feed the power to other devices. For control purposes, non-linear and linear converter models are derived. The transfer functions of the linear model are used to implement the regulator using a current-mode control scheme. Finally, experimental results for a nominal output voltage of 48 V at 500 W are obtained for the converter in open-loop and closed-loop tests.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061144
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1145: A Review of Machine Learning Methods
Recently Applied to FTIR Spectroscopy Data for the Analysis of Human Blood
Cells
Authors: Ahmed Fadlelmoula, Susana O. Catarino, Graça Minas, Vítor Carvalho
First page: 1145
Abstract: Machine learning (ML) is a broad term encompassing several methods that allow us to learn from data. These methods may permit large real-world databases to be more rapidly translated to applications to inform patient–provider decision-making. This paper presents a review of articles that discuss the use of Fourier transform infrared (FTIR) spectroscopy and ML for human blood analysis between the years 2019–2023. The literature review was conducted to identify published research of employed ML linked with FTIR for distinction between pathological and healthy human blood cells. The articles’ search strategy was implemented and studies meeting the eligibility criteria were evaluated. Relevant data related to the study design, statistical methods, and strengths and limitations were identified. A total of 39 publications in the last 5 years (2019–2023) were identified and evaluated for this review. Diverse methods, statistical packages, and approaches were used across the identified studies. The most common methods included support vector machine (SVM) and principal component analysis (PCA) approaches. Most studies applied internal validation and employed more than one algorithm, while only four studies applied one ML algorithm to the data. A wide variety of approaches, algorithms, statistical software, and validation strategies were employed in the application of ML methods. There is a need to ensure that multiple ML approaches are used, the model selection strategy is clearly defined, and both internal and external validation are necessary to be sure that the discrimination of human blood cells is being made with the highest efficient evidence.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061145
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1146: Parameter Optimization for Printing
Barium Titanate Piezoelectric Ceramics through Digital Light Processing
Authors: Dongcai Zhang, Yaodong Yang, Wei-Feng Rao
First page: 1146
Abstract: Digital light processing (DLP) technology has emerged as a promising 3D printing technology with the potential for the efficient manufacturing of complex ceramic devices. However, the quality of printed products is highly dependent on various process parameters, including slurry formulation, heat treatment process, and poling process. This paper optimizes the printing process with respect to these key parameters, such as using a ceramic slurry with 75 wt% powder content. The employed degreasing heating rate is 4 °C/min, the carbon-removing heating rate is 4 °C/min, and the sintering heating rate is 2 °C/min for heat treatment of the printed green body. The resulting parts are polarized using a poling field of 10 kV/cm, a poling time of 50 min, and a poling temperature of 60 °C, which yields a piezoelectric device with a high piezoelectric constant of 211 pC/N. To demonstrate the practical application of the device, its use as a force sensor and magnetic sensor is validated.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061146
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1147: Structure Design and Characterization
of 3D Printing System of Thermal Battery Electrode Ink Film
Authors: Fengli Liu, Jiale Lu, Yongping Hao, Yao Chang, Kuaikuai Yu, Shuangjie Liu, Zhiwei Chu
First page: 1147
Abstract: In this paper, a 3D printing system for a thermal battery electrode ink film is set up and investigated based on the on-demand microdroplet ejection technology. The optimal structural dimensions of the spray chamber and metal membrane of the micronozzle are determined via simulation analysis. The workflow and functional requirements of the printing system are set up. The printing system includes a pretreatment system, piezoelectric micronozzle, motion control system, piezoelectric drive system, sealing system, and liquid conveying system. Different printing parameters are compared to obtain optimized printing parameters, which can be attributed to the optimal pattern of the film. The feasibility and controllability of 3D printing methods are verified by printing tests. The size and output speed of the droplets can be controlled by adjusting the amplitude and frequency of the driving waveform acting on the piezoelectric actuator. So, the required shape and thickness of the film can be achieved. An ink film in terms of nozzle diameter = 0.6 mm, printing height = 8 mm, wiring width = 1 mm, input voltage = 3 V and square wave signal frequency = 35 Hz can be achieved. The electrochemical performance of thin-film electrodes is crucial in thermal batteries. The voltage of the thermal battery reaches its peak and tends to flatten out at around 100 s when using this printed film. The electrical performance of the thermal batteries using the printed thin films is found to be stable. This stabilized voltage makes it applicable to thermal batteries.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061147
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1148: Sustainable Dry Machining of Stainless
Steel with Microwave-Treated Tungsten Carbide Cutting Tools
Authors: Itemogeng Bernatt Babe, Kapil Gupta, Sujeet Kumar Chaubey
First page: 1148
Abstract: This paper presents a research investigation conducted on the turning of stainless steel 316 material under a dry environment using microwave-treated cutting tool inserts. Plain tungsten carbide WC tool inserts were exposed to microwave treatment for enhancement of their performance characteristics. It was found that a 20-min microwave treatment resulted in the best tool hardness and metallurgical characteristics. These tool inserts have been used to machine SS 316 material following the Taguchi L9 design of experimental techniques. A total of eighteen experiments have been conducted by varying three main machining parameters, i.e., cutting speed, feed rate, and depth of cut, at three levels per parameter. It has been found that tool flank wear increased with all three parameters and surface roughness decreased. At the longest dept of cut, surface roughness increased. An abrasion wear mechanism was found on the tool flank face at a high machining speed and adhesion at low speed. Chips with a helical shape and low serrations have been investigated. Turning SS 316 at optimum machining parameters of 170 m/min cutting speed, 0.2 mm/rev feed rate, and 1 mm depth of cut, as obtained by the multiperformance optimization technique grey relational analysis, resulted in the best values of all machinability indicators: 242.21 µm tool flank wear, 3.81 µm mean roughness depth, and 34,000 mm3/min material removal rate, at a single parameter setting. In terms of research achievements, the percentage reduction in surface roughness is approximately 30% and represents an almost ten-fold improvement in the material removal rate. The combination of machining parameters of 70 m/min cutting speed, 0.1 mm/rev feed rate, and 0.5 mm depth of cut is optimum for the lowest value of tool flank wear when considered for single parameter optimization.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061148
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1149: A Review of System-in-Package
Technologies: Application and Reliability of Advanced Packaging
Authors: Haoyu Wang, Jianshe Ma, Yide Yang, Mali Gong, Qinheng Wang
First page: 1149
Abstract: The system-in-package (SiP) has gained much interest in the current rapid development of integrated circuits (ICs) due to its advantages of integration, shrinking, and high density. This review examined the SiP as its focus, provides a list of the most-recent SiP innovations based on market needs, and discusses how the SiP is used in various fields. Reliability issues must be resolved if the SiP is to operate normally. Three factors—thermal management, mechanical stress and electrical properties—can be paired with specific examples in order to detect and improve package reliability. This review provides a thorough overview of SiP technology, serves as a guide and foundation for the SiP in package reliability design, and addresses the challenges and potential for further development of this kind of package.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061149
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1150: A Physics-Informed Automatic Neural
Network Generation Framework for Emerging Device Modeling
Authors: Guangxin Guo, Hailong You, Cong Li, Zhengguang Tang, Ouwen Li
First page: 1150
Abstract: With the rapid development of semiconductor technology, traditional equation-based modeling faces challenges in accuracy and development time. To overcome these limitations, neural network (NN)-based modeling methods have been proposed. However, the NN-based compact model encounters two major issues. Firstly, it exhibits unphysical behaviors such as un-smoothness and non-monotonicity, which hinder its practical use. Secondly, finding an appropriate NN structure with high accuracy requires expertise and is time-consuming. In this paper, we propose an Automatic Physical-Informed Neural Network (AutoPINN) generation framework to solve these challenges. The framework consists of two parts: the Physics-Informed Neural Network (PINN) and the two-step Automatic Neural Network (AutoNN). The PINN is introduced to resolve unphysical issues by incorporating physical information. The AutoNN assists the PINN in automatically determining an optimal structure without human involvement. We evaluate the proposed AutoPINN framework on the gate-all-around transistor device. The results demonstrate that AutoPINN achieves an error of less than 0.05%. The generalization of our NN is promising, as validated by the test error and the loss landscape. The results demonstrate smoothness in high-order derivatives, and the monotonicity can be well-preserved. We believe that this work has the potential to accelerate the development and simulation process of emerging devices.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061150
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1151: Fabrication and Characterization of
Thin Metal Films Deposited by Electroless Plating with Organic Additives
for Electrical Circuits Applications
Authors: Nikita S. Buylov, Nadezhda V. Sotskaya, Oleg A. Kozaderov, Khidmet S. Shikhaliev, Andrey Yu. Potapov, Vladimir A. Polikarchuk, Sergey V. Rodivilov, Vitaly V. Pobedinskiy, Margaryta V. Grechkina, Pavel V. Seredin
First page: 1151
Abstract: In our work, we studied thin nickel films deposited by electroless plating for use as a barrier and seed layer in the through-silicon vias (TSV) technology. El-Ni coatings were deposited on a copper substrate from the original electrolyte and with the use of various concentrations of organic additives in the composition of the electrolyte. The surface morphology, crystal state, and phase composition of the deposited coatings were studied by SEM, AFM, and XRD methods. The El-Ni coating deposited without the use of an organic additive has an irregular topography with rare phenocrysts of globular formations of hemispherical shape and a root mean square roughness value of 13.62 nm. The phosphorus concentration in the coating is 9.78 wt.%. According to the results of the X-ray diffraction studies of El-Ni, the coating deposited without the use of an organic additive has a nanocrystalline structure with an average nickel crystallite size of 2.76 nm. The influence of the organic additive is seen in the smoothening of the samples surface. The root mean square roughness values of the El-Ni sample coatings vary within 2.09–2.70 nm. According to microanalysis data the phosphorus concentration in the developed coatings is ~4.7–6.2 wt.%. The study of the crystalline state of the deposited coatings by X-ray diffraction made it possible to detect two arrays of nanocrystallites in their structure, with average sizes of 4.8–10.3 nm and 1.3–2.6 nm.
Citation: Micromachines
PubDate: 2023-05-29
DOI: 10.3390/mi14061151
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1152: Laser Bioprinting with Cell Spheroids:
Accurate and Gentle
Authors: Ekaterina D. Minaeva, Artem A. Antoshin, Nastasia V. Kosheleva, Polina I. Koteneva, Sergey A. Gonchukov, Svetlana I. Tsypina, Vladimir I. Yusupov, Peter S. Timashev, Nikita V. Minaev
First page: 1152
Abstract: Laser printing with cell spheroids can become a promising approach in tissue engineering and regenerative medicine. However, the use of standard laser bioprinters for this purpose is not optimal as they are optimized for transferring smaller objects, such as cells and microorganisms. The use of standard laser systems and protocols for the transfer of cell spheroids leads either to their destruction or to a significant deterioration in the quality of bioprinting. The possibilities of cell spheroids printing by laser-induced forward transfer in a gentle mode, which ensures good cell survival ~80% without damage and burns, were demonstrated. The proposed method showed a high spatial resolution of laser printing of cell spheroid geometric structures at the level of 62 ± 33 µm, which is significantly less than the size of the cell spheroid itself. The experiments were performed on a laboratory laser bioprinter with a sterile zone, which was supplemented with a new optical part based on the Pi-Shaper element, which allows for forming laser spots with different non-Gaussian intensity distributions. It is shown that laser spots with an intensity distribution profile of the “Two rings” type (close to Π-shaped) and a size comparable to a spheroid are optimal. To select the operating parameters of laser exposure, spheroid phantoms made of a photocurable resin and spheroids made from human umbilical cord mesenchymal stromal cells were used.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061152
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1153: A Compact MIMO Multiband Antenna for
5G/WLAN/WIFI-6 Devices
Authors: Ayyaz Ali, Mehr E Munir, Mohamed Marey, Hala Mostafa, Zahriladha Zakaria, Ahmed Jamal Abdullah Al-Gburi, Farooq Ahmed Bhatti
First page: 1153
Abstract: This research work presents a compact design of a Multiple-Input Multiple-Output (MIMO) multiband antenna along with high-isolation characteristics. The presented antenna was designed for 3.50 GHz, 5.50 GHz, and 6.50 GHz frequencies for 5G cellular, 5G WiFi, and WiFi-6, respectively. The fabrication of the aforementioned design was undertaken using FR-4 (1.6 mm thickness) substrate material with a loss tangent and relative permittivity of about 0.025 and 4.30, respectively. The two-element MIMO multiband antenna was miniaturized to 16 × 28 × 1.6 mm3, making it desirable for devices operating in 5G bands. High isolation (>15 dB) was attained with thorough testing without employing a decoupling scheme in the design. Laboratory measurements resulted in a peak gain of 3.49 dBi and an efficiency of around 80% in the entire operating band. The evaluation of the presented MIMO multiband antenna was carried out in terms of the envelope correlation coefficient (ECC), diversity gain (DG), total active reflection coefficient (TARC), and Channel Capacity Loss (CCL). The measured ECC was less than 0.04, and the DG was well above 9.50. The observed TARC was also lower than −10 dB, and the CCL was below 0.4 bits/s/Hz in the entire operating band. The presented MIMO multiband antenna was analyzed and simulated using CST Studio Suite 2020.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061153
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1154: An Optimal Shaped Sensor Array
Derivation
Authors: Marco Dibiase, Luca De Marchi
First page: 1154
Abstract: In Structural Health Monitoring (SHM) applications, the Direction of Arrival (DoA) estimation of Guided Waves (GW) on sensor arrays is often used as a fundamental means to locate Acoustic Sources (AS) generated by damages growth or undesired impacts in thin-wall structures (e.g., plates or shells). In this paper, we consider the problem of designing the arrangement and shape of piezo-sensors in planar clusters in order to optimize the DoA estimation performance in noise-affected measurements. We assume that: (i) the wave propagation velocity is unknown, (ii) the DoA is estimated via the time delays of wavefronts between sensors, and (iii) the maximum value of the time delays is limited. The optimality criterion is derived basing on the Theory of Measurements. The sensor array design is so that the DoA variance is minimized in an average sense by exploiting the Calculus of Variations. In this way, considering a three-sensor cluster and a monitored angles sector of 90°, the optimal time delays–DoA relations are derived. A suitable re-shaping procedure is used to impose such relations and, at the same time, to induce the same spatial filtering effect between sensors so that the sensor acquired signals are equal except for a time-shift. In order to achieve the last aim, the sensors shape is realized by exploiting a technique called Error Diffusion, which is able to emulate piezo-load functions with continuously modulated values. In this way, the Shaped Sensors Optimal Cluster (SS-OC) is derived. A numerical assessment via Green’s functions simulations shows improved performance in DoA estimation by means of the SS-OC when compared to clusters realized with conventional piezo-disk transducers.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061154
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1155: An Arrhythmia Classification Model
Based on Vision Transformer with Deformable Attention
Authors: Yanfang Dong, Miao Zhang, Lishen Qiu, Lirong Wang, Yong Yu
First page: 1155
Abstract: The electrocardiogram (ECG) is a highly effective non-invasive tool for monitoring heart activity and diagnosing cardiovascular diseases (CVDs). Automatic detection of arrhythmia based on ECG plays a critical role in the early prevention and diagnosis of CVDs. In recent years, numerous studies have focused on using deep learning methods to address arrhythmia classification problems. However, the transformer-based neural network in current research still has a limited performance in detecting arrhythmias for the multi-lead ECG. In this study, we propose an end-to-end multi-label arrhythmia classification model for the 12-lead ECG with varied-length recordings. Our model, called CNN-DVIT, is based on a combination of convolutional neural networks (CNNs) with depthwise separable convolution, and a vision transformer structure with deformable attention. Specifically, we introduce the spatial pyramid pooling layer to accept varied-length ECG signals. Experimental results show that our model achieved an F1 score of 82.9% in CPSC-2018. Notably, our CNN-DVIT outperforms the latest transformer-based ECG classification algorithms. Furthermore, ablation experiments reveal that the deformable multi-head attention and depthwise separable convolution are both efficient in extracting features from multi-lead ECG signals for diagnosis. The CNN-DVIT achieved good performance for the automatic arrhythmia detection of ECG signals. This indicates that our research can assist doctors in clinical ECG analysis, providing important support for the diagnosis of arrhythmia and contributing to the development of computer-aided diagnosis technology.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061155
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1156: Spiral Chiral Metamaterial Structure
Shape for Optical Activity Improvements
Authors: Kohei Maruyama, Miyako Mizuna, Takuya Kosuge, Yuki Takeda, Eiji Iwase, Tetsuo Kan
First page: 1156
Abstract: We report on a spiral structure suitable for obtaining a large optical response. We constructed a structural mechanics model of the shape of the planar spiral structure when deformed and verified the effectiveness of the model. As a verification structure, we fabricated a large-scale spiral structure that operates in the GHz band by laser processing. Based on the GHz radio wave experiments, a more uniform deformation structure exhibited a higher cross-polarization component. This result suggests that uniform deformation structures can improve circular dichroism. Since large-scale devices enable speedy prototype verification, the obtained knowledge can be exported to miniaturized-scale devices, such as MEMS terahertz metamaterials.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061156
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1157: The Effect of 3D Printing Tilt Angle
on the Penetration of 3D-Printed Microneedle Arrays
Authors: Mahmood Razzaghi, Mohsen Akbari
First page: 1157
Abstract: Microneedle arrays (MNAs) are emerging devices that are mainly used for drug delivery and diagnostic applications through the skin. Different methods have been used to fabricate MNAs. Recently developed fabrication methods based on 3D printing have many advantages compared to conventional fabrication methods, such as faster fabrication in one step and the ability to fabricate complex structures with precise control over their geometry, form, size, and mechanical and biological properties. Despite the several advantages that 3D printing offers for the fabrication of microneedles, their poor penetration capability into the skin should be improved. MNAs need a sharp needle tip to penetrate the skin barrier layer, the stratum corneum (SC). This article presents a method to improve the penetration of 3D-printed microneedle arrays by investigating the effect of the printing angle on the penetration force of MNAs. The penetration force needed to puncture the skin for MNAs fabricated using a commercial digital light processing (DLP) printer, with different printing tilt angles (0–60°), was measured in this study. The results showed that the minimum puncture force was achieved using a 45° printing tilt angle. Using this angle, the puncture force was reduced by 38% compared to MNAs printed with a tilting angle of 0°. We also identified that a tip angle of 120° resulted in the smallest penetration force needed to puncture the skin. The outcomes of the research show that the presented method can significantly improve the penetration capability of 3D-printed MNAs into the skin.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061157
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1158: Advances in Femtosecond Laser
GHz-Burst Drilling of Glasses: Influence of Burst Shape and Duration
Authors: Pierre Balage, Guillaume Bonamis, Manon Lafargue, Théo Guilberteau, Martin Delaigue, Clemens Hönninger, Jie Qiao, John Lopez, Inka Manek-Hönninger
First page: 1158
Abstract: The femtosecond GHz-burst mode laser processing has attracted much attention in the last few years. Very recently, the first percussion drilling results obtained in glasses using this new regime were reported. In this study, we present our latest results on top-down drilling in glasses, focusing specifically on the influence of burst duration and shape on the hole drilling rate and the quality of the drilled holes, wherein holes of very high quality with a smooth and glossy inner surface can be obtained. We show that a decreasing energy repartition of the pulses within the burst can increase the drilling rate, but the holes saturate at lower depths and present lower quality than holes drilled with an increasing or flat energy distribution. Moreover, we give an insight into the phenomena that may occur during drilling as a function of the burst shape.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061158
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1159: Multidirectional Piezoelectric
Vibration Energy Harvester Based on Cam Rotor Mechanism
Authors: Xin Jiang, Yan Liu, Jiaming Wei, Haotian Yang, Bin Yin, Hongbo Qin, Weidong Wang
First page: 1159
Abstract: The techniques that harvest mechanical energy from low-frequency, multidirectional environmental vibrations have been considered a promising strategy to implement a sustainable power source for wireless sensor networks and the Internet of Things. However, the obvious inconsistency in the output voltage and operating frequency among different directions may bring a hindrance to energy management. To address this issue, this paper reports a cam-rotor-based approach for a multidirectional piezoelectric vibration energy harvester. The cam rotor can transform vertical excitation into a reciprocating circular motion, producing a dynamic centrifugal acceleration to excite the piezoelectric beam. The same beam group is utilized when harvesting vertical and horizontal vibrations. Therefore, the proposed harvester reveals similar characterization in its resonant frequency and output voltage at different working directions. The structure design and modeling, device prototyping and experimental validation are conducted. The results show that the proposed harvester can produce a peak voltage of up to 42.4 V under a 0.2 g acceleration with a favorable power of 0.52 mW, and the resonant frequency for each operating direction is stable at around 3.7 Hz. Practical applications in lighting up LEDs and powering a WSN system demonstrate the promising potential of the proposed approach in capturing energy from ambient vibrations to construct self-powered engineering systems for structural health monitoring, environmental measuring, etc.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061159
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1160: Comparative Analysis of Minimum Chip
Thickness, Surface Quality and Burr Formation in Micro-Milling of Wrought
and Selective Laser Melted Ti64
Authors: Uçan Karakılınç, Berkay Ergene, Bekir Yalçın, Kubilay Aslantaş, Ali Erçetin
First page: 1160
Abstract: Selective laser melting (SLM) is a three-dimensional (3D) printing process that can manufacture functional parts with complex geometries as an alternative to using traditional processes, such as machining wrought metal. If precision and a high surface finish are required, particularly for creating miniature channels or geometries smaller than 1 mm, the fabricated parts can be further machined. Therefore, micro milling plays a significant role in the production of such miniscule geometries. This experimental study compares the micro machinability of Ti-6Al-4V (Ti64) parts produced via SLM compared with wrought Ti64. The aim is to investigate the effect of micro milling parameters on the resulting cutting forces (Fx, Fy, and Fz), surface roughness (Ra and Rz), and burr width. In the study, a wide range of feed rates was considered to determine the minimum chip thickness. Additionally, the effects of the depth of cut and spindle speed were observed by taking into account four different parameters. The manufacturing method for the Ti64 alloy does not affect the minimum chip thickness (MCT) and the MCT for both the SLM and wrought is 1 μm/tooth. SLM parts exhibit acicular α martensitic grains, which result in higher hardness and tensile strength. This phenomenon prolongs the transition zone of micro-milling for the formation of minimum chip thickness. Additionally, the average cutting force values for SLM and wrought Ti64 fluctuated between 0.072 N and 1.96 N, depending on the micro milling parameters used. Finally, it is worth noting that micro-milled SLM workpieces exhibit lower areal surface roughness than wrought ones.
Citation: Micromachines
PubDate: 2023-05-30
DOI: 10.3390/mi14061160
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1161: Weak Capacitance Detection Circuit of
Micro-Hemispherical Gyroscope Based on Common-Mode Feedback Fusion
Modulation and Demodulation
Authors: Xiaoyang Zhang, Pinghua Li, Xuye Zhuang, Yunlong Sheng, Jinghao Liu, Zhongfeng Gao, Zhiyu Yu
First page: 1161
Abstract: As an effective capacitance signal produced by a micro-hemisphere gyro is usually below the pF level, and the capacitance reading process is susceptible to parasitic capacitance and environmental noise, it is highly difficult to acquire an effective capacitance signal. Reducing and suppressing noise in the gyro capacitance detection circuit is a key means to improve the performance of detecting the weak capacitance generated by MEMS gyros. In this paper, we propose a novel capacitance detection circuit, where three different means are utilized to achieve noise reduction. Firstly, the input common-mode feedback is applied to the circuit to solve the input common-mode voltage drift caused by both parasitic capacitance and gain capacitance. Secondly, a low-noise, high-gain amplifier is used to reduce the equivalent input noise. Thirdly, the modulator–demodulator and filter are introduced to the proposed circuit to effectively mitigate the side effects of noise; thus, the accuracy of capacitance detection can be further improved. The experimental results show that with the input voltage of 6 V, the newly designed circuit produces an output dynamic range of 102 dB and the output voltage noise of 5.69 nV/√Hz, achieving a sensitivity of 12.53 V/pF.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061161
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1162: A Study on the Material Removal
Characteristics and Damage Mechanism of Lapping for Pressureless Sintered
Silicon Carbide (SSiC) Microlens Cavity
Authors: Tianfeng Zhou, Zhongyi Li, Weijia Guo, Peng Liu, Bin Zhao, Xibin Wang
First page: 1162
Abstract: Microlens arrays have been widely employed to control the reflection, refraction, and diffraction characteristics of light due to its distinctive surface properties. Precision glass molding (PGM) is the primary method for the mass production of microlens arrays, of which pressureless sintered silicon carbide (SSiC) is a typical mold material due to its excellent wear resistance, high thermal conductivity, high-temperature resistance, and low thermal expansion. However, the high hardness of SSiC makes it hard to be machined, especially for optical mold material that requires good surface quality. The lapping efficiency of SSiC molds is quite low. and the underlying mechanism remains insufficiently explored. In this study, an experimental study has been performed on SSiC. A spherical lapping tool and diamond abrasive slurry have been utilized and various parameters have been carried out to achieve fast material removal. The material removal characteristics and damage mechanism have been illustrated in detail. The findings reveal that the material removal mechanism involves a combination of ploughing, shearing, micro-cutting, and micro-fracturing, which aligns well with the results obtained from finite element method (FEM) simulations. This study serves as preliminary reference for the optimization of the precision machining of SSiC PGM molds with high efficiency and good surface quality.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061162
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1163: Differential Confocal Optical Probes
with Optimized Detection Efficiency and Pearson Correlation Coefficient
Strategy Based on the Peak-Clustering Algorithm
Authors: Zhiyi Wang, Tingyu Wang, Yongqiang Yang, Xiaotao Mi, Jianli Wang
First page: 1163
Abstract: Quantifying free-form surfaces using differential confocal microscopy can be challenging, as it requires balancing accuracy and efficiency. When the axial scanning mechanism involves sloshing and the measured surface has a finite slope, traditional linear fitting can introduce significant errors. This study introduces a compensation strategy based on Pearson’s correlation coefficient to effectively reduce measurement errors. Additionally, a fast-matching algorithm based on peak clustering was proposed to meet real-time requirements for non-contact probes. To validate the effectiveness of the compensation strategy and matching algorithm, detailed simulations and physical experiments were conducted. The results showed that for a numerical aperture of 0.4 and a depth of slope < 12°, the measurement error was <10 nm, improving the speed of the traditional algorithm system by 83.37%. Furthermore, repeatability and anti-disturbance experiments demonstrated that the proposed compensation strategy is simple, efficient, and robust. Overall, the proposed method has significant potential for application in the realization of high-speed measurements of free-form surfaces.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061163
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1164: Thermal Analysis of a Reactive
Variable Viscosity TiO2-PAO Nanolubricant in a Microchannel Poiseuille
Flow
Authors: Oluwole Daniel Makinde, Anuoluwa Esther Makinde
First page: 1164
Abstract: This paper examines the flow structure and heat transfer characteristics of a reactive variable viscosity polyalphaolefin (PAO)-based nanolubricant containing titanium dioxide (TiO2) nanoparticles in a microchannel. The nonlinear model equations are obtained and numerically solved via the shooting method with Runge–Kutta–Fehlberg integration scheme. Pertinent results depicting the effects of emerging thermophysical parameters on the reactive lubricant velocity, temperature, skin friction, Nusselt number and thermal stability criteria are presented graphically and discussed. It is found that the Nusselt number and thermal stability of the flow process improve with exothermic chemical kinetics, Biot number, and nanoparticles volume fraction but lessen with a rise in viscous dissipation and activation energy.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061164
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1165: Revolutionizing Prosthetic Design with
Auxetic Metamaterials and Structures: A Review of Mechanical Properties
and Limitations
Authors: Muhammad Faris Fardan, Bhre Wangsa Lenggana, U Ubaidillah, Seung-Bok Choi, Didik Djoko Susilo, Sohaib Zia Khan
First page: 1165
Abstract: Prosthetics have come a long way since their inception, and recent advancements in materials science have enabled the development of prosthetic devices with improved functionality and comfort. One promising area of research is the use of auxetic metamaterials in prosthetics. Auxetic materials have a negative Poisson’s ratio, which means that they expand laterally when stretched, unlike conventional materials, which contract laterally. This unique property allows for the creation of prosthetic devices that can better conform to the contours of the human body and provide a more natural feel. In this review article, we provide an overview of the current state of the art in the development of prosthetics using auxetic metamaterials. We discuss the mechanical properties of these materials, including their negative Poisson’s ratio and other properties that make them suitable for use in prosthetic devices. We also explore the limitations that currently exist in implementing these materials in prosthetic devices, including challenges in manufacturing and cost. Despite these challenges, the future prospects for the development of prosthetic devices using auxetic metamaterials are promising. Continued research and development in this field could lead to the creation of more comfortable, functional, and natural-feeling prosthetic devices. Overall, the use of auxetic metamaterials in prosthetics represents a promising area of research with the potential to improve the lives of millions of people around the world who rely on prosthetic devices.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061165
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1166: GaN/Si Heterojunction VDMOS with High
Breakdown Voltage and Low Specific On-Resistance
Authors: Xin Yang, Baoxing Duan, Yintang Yang
First page: 1166
Abstract: A novel VDMOS with the GaN/Si heterojunction (GaN/Si VDMOS) is proposed in this letter to optimize the breakdown voltage (BV) and the specific on-resistance (Ron,sp) by Breakdown Point Transfer (BPT), which transfers the breakdown point from the high-electric-field region to the low-electric-field region and improves the BV compared with conventional Si VDMOS. The results of the TCAD simulation show that the optimized BV of the proposed GaN/Si VDMOS increases from 374 V to 2029 V compared with the conventional Si VDMOS with the same drift region length of 20 μm, and the Ron,sp of 17.2 mΩ·cm2 is lower than 36.5 mΩ·cm2 for the conventional Si VDMOS. Due to the introduction of the GaN/Si heterojunction, the breakdown point is transferred by BPT from the higher-electric-field region with the largest radius of curvature to the low-electric-field region. The interfacial state effects of the GaN/Si are analyzed to guide the fabrication of the GaN/Si heterojunction MOSFETs.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061166
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1167: Depth-Enhanced Holographic Super
Multi-View Maxwellian Display Based on Variable Filter Aperture
Authors: Kefeng Tu, Qiyang Chen, Zi Wang, Guoqiang Lv, Qibin Feng
First page: 1167
Abstract: The super multi-view (SMV) near-eye display (NED) effectively provides depth cues for three-dimensional (3D) displays by projecting multiple viewpoint images or parallax images onto the retina simultaneously. Previous SMV NED suffers from a limited depth of field (DOF) due to the fixed image plane. Aperture filtering is widely used to enhance the DOF; however, an invariably sized aperture may have opposite effects on objects with different reconstruction depths. In this paper, a holographic SMV display based on the variable filter aperture is proposed to enhance the DOF. In parallax image acquisition, multiple groups of parallax images, each group recording a part of the 3D scene on a fixed depth range, are captured first. In the hologram calculation, each group of wavefronts at the image recording plane (IRP) is calculated by multiplying the parallax images with the corresponding spherical wave phase. Then, they are propagated to the pupil plane and multiplied by the corresponding aperture filter function. The size of the filter aperture is variable which is determined by the depth of the object. Finally, the complex amplitudes at the pupil plane are back-propagated to the holographic plane and added together to form the DOF-enhanced hologram. Simulation and experimental results verify the proposed method could improve the DOF of holographic SMV display, which will contribute to the application of 3D NED.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061167
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1168: Study of CdS/CdS Nanoparticles Thin
Films Deposited by Soft Chemistry for Optoelectronic Applications
Authors: Laura Aislinn Carrasco-Chavez, José F. Rubio-Valle, Abimael Jiménez-Pérez, José E. Martín-Alfonso, Amanda Carrillo-Castillo
First page: 1168
Abstract: Chalcogenides semiconductors are currently being studied as active layers in the development of electronic devices in the field of applied technology. In the present paper, cadmium sulfide (CdS) thin films containing nanoparticles of the same material as the active layer were produced and analyzed for their application in fabricating optoelectronic devices. CdS thin films and CdS nanoparticles were obtained via soft chemistry at low temperatures. The CdS thin film was deposited via chemical bath deposition (CBD); the CdS nanoparticles were synthesized via the precipitation method. The construction of a homojunction was completed by incorporating CdS nanoparticles on CdS thin films deposited via CBD. CdS nanoparticles were deposited using the spin coating technique, and the effect of thermal annealing on the deposited films was investigated. In the modified thin films with nanoparticles, a transmittance of about 70% and a band gap between 2.12 eV and 2.35 eV were obtained. The two characteristic phonons of the CdS were observed via Raman spectroscopy, and the CdS thin films/CdS nanoparticles showed a hexagonal and cubic crystalline structure with average crystallite size of 21.3–28.4 nm, where hexagonal is the most stable for optoelectronic applications, with roughness less than 5 nm, indicating that CdS is relatively smooth, uniform and highly compact. In addition, the characteristic curves of current-voltage for as-deposited and annealed thin films showed that the metal-CdS with the CdS nanoparticle interface exhibits ohmic behavior.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061168
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1169: A High Performance All-Textile
Wearable Antenna for Wristband Application
Authors: Asma Ejaz, Iqra Jabeen, Zia Ullah Khan, Akram Alomainy, Khaled Aljaloud, Ali H. Alqahtani, Niamat Hussain, Rifaqat Hussain, Yasar Amin
First page: 1169
Abstract: A compact, conformal, all-textile wearable antenna is proposed in this paper for the 2.45 GHz ISM (Industrial, Scientific and Medical) band. The integrated design consists of a monopole radiator backed by a 2 × 1 Electromagnetic Band Gap (EBG) array, resulting in a small form factor suitable for wristband applications. An EBG unit cell is optimized to work in the desired operating band, the results of which are further explored to achieve bandwidth maximization via floating EBG ground. A monopole radiator is made to work in association with the EBG layer to produce the resonance in the ISM band with plausible radiation characteristics. The fabricated design is tested for free space performance analysis and subjected to human body loading. The proposed antenna design achieves bandwidth of 2.39 GHz to 2.54 GHz with a compact footprint of 35.4 × 82.4 mm2. The experimental investigations reveal that the reported design adequately retains its performance while operating in close proximity to human beings. The presented Specific Absorption Rate (SAR) analysis reveals 0.297 W/kg calculated at 0.5 W input power, which certifies that the proposed antenna is safe for use in wearable devices.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061169
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1170: Accurate Stride-Length Estimation
Based on LT-StrideNet for Pedestrian Dead Reckoning Using a Shank-Mounted
Sensor
Authors: Yong Li, Guopei Zeng, Luping Wang, Ke Tan
First page: 1170
Abstract: Pedestrian dead reckoning (PDR) is a self-contained positioning technology and has been a significant research topic in recent years. Pedestrian-stride-length estimation is the core part of the PDR system and directly affects the performance of the PDR. The current stride-length-estimation method is difficult to adapt to changes in pedestrian walking speed, which leads to a rapid increase in the error of the PDR. In this paper, a new deep-learning model based on long short-term memory (LSTM) and Transformer, LT-StrideNet, is proposed to estimate pedestrian-stride length. Next, a shank-mounted PDR framework is built based on the proposed stride-length-estimation method. In the PDR framework, the detection of pedestrian stride is achieved by peak detection with a dynamic threshold. An extended Kalman filter (EKF) model is adopted to fuse the gyroscope, accelerometer, and magnetometer. The experimental results show that the proposed stride-length-estimation method can effectively adapt to changes in pedestrian walking speed, and our PDR framework has excellent positioning performance.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061170
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1171: Biological Interfacial Materials for
Organic Light-Emitting Diodes
Authors: Amjad Islam, Syed Hamad Ullah Shah, Zeeshan Haider, Muhammad Imran, Al Amin, Syed Kamran Haider, Ming-De Li
First page: 1171
Abstract: Organic optoelectronic devices have received appreciable attention due to their low cost, mechanical flexibility, band-gap engineering, lightness, and solution processability over a broad area. Specifically, realizing sustainability in organic optoelectronics, especially in solar cells and light-emitting devices, is a crucial milestone in the evolution of green electronics. Recently, the utilization of biological materials has appeared as an efficient means to alter the interfacial properties, and hence improve the performance, lifetime and stability of organic light-emitting diodes (OLEDs). Biological materials can be known as essential renewable bio-resources obtained from plants, animals and microorganisms. The application of biological interfacial materials (BIMs) in OLEDs is still in its early phase compared to the conventional synthetic interfacial materials; however, their fascinating features (such as their eco-friendly nature, biodegradability, easy modification, sustainability, biocompatibility, versatile structures, proton conductivity and rich functional groups) are compelling researchers around the world to construct innovative devices with enhanced efficiency. In this regard, we provide an extensive review of BIMs and their significance in the evolution of next-generation OLED devices. We highlight the electrical and physical properties of different BIMs, and address how such characteristics have been recently exploited to make efficient OLED devices. Biological materials such as ampicillin, deoxyribonucleic acid (DNA), nucleobases (NBs) and lignin derivatives have demonstrated significant potential as hole/electron transport layers as well as hole/electron blocking layers for OLED devices. Biological materials capable of generating a strong interfacial dipole can be considered as a promising prospect for alternative interlayer materials for OLED applications.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061171
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1172: A False Trigger-Strengthened and
Area-Saving Power-Rail Clamp Circuit with High ESD Performance
Authors: Boyang Ma, Shupeng Chen, Shulong Wang, Lingli Qian, Zeen Han, Wei Huang, Xiaojun Fu, Hongxia Liu
First page: 1172
Abstract: A power clamp circuit, which has good immunity to false trigger under fast power-on conditions with a 20 ns rising edge, is proposed in this paper. The proposed circuit has a separate detection component and an on-time control component which enable it to distinguish between electrostatic discharge (ESD) events and fast power-on events. As opposed to other on-time control techniques, instead of large resistors or capacitors, which can cause a large occupation of the layout area, we use a capacitive voltage-biased p-channel MOSFET in the on-time control part of the proposed circuit. The capacitive voltage-biased p-channel MOSFET is in the saturation region after the ESD event is detected, which can serve as a large equivalent resistance (~106 Ω) in the structure. The proposed power clamp circuit offers several advantages compared to the traditional circuit, such as having at least 70% area savings in the trigger circuit area (30% area savings in the whole circuit area), supporting a power supply ramp time as fast as 20 ns, dissipating the ESD energy more cleanly with little residual charge, and recovering faster from false triggers. The rail clamp circuit also offers robust performance in an industry-standard PVT (process, voltage, and temperature) space and has been verified by the simulation results. Showing good performance of human body model (HBM) endurance and high immunity to false trigger, the proposed power clamp circuit has great potential for application in ESD protection.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061172
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1173: Visible Pulsed Laser-Assisted
Selective Killing of Cancer Cells with PVP-Capped Plasmonic Gold Nanostars
Authors: Aniket Mishra, Rafia Inaam, Shunya Okamoto, Takayuki Shibata, Tuhin Subhra Santra, Moeto Nagai
First page: 1173
Abstract: A new generation of nanoscale photosensitizer agents has improved photothermal capabilities, which has increased the impact of photothermal treatments (PTTs) in cancer therapy. Gold nanostars (GNS) are promising for more efficient and less invasive PTTs than gold nanoparticles. However, the combination of GNS and visible pulsed lasers remains unexplored. This article reports the use of a 532 nm nanosecond pulse laser and polyvinylpyrrolidone (PVP)-capped GNS to kill cancer cells with location-specific exposure. Biocompatible GNS were synthesized via a simple method and were characterized under FESEM, UV–visible spectroscopy, XRD analysis, and particle size analysis. GNS were incubated over a layer of cancer cells that were grown in a glass Petri dish. A nanosecond pulsed laser was irradiated on the cell layer, and cell death was verified via propidium iodide (PI) staining. We assessed the effectiveness of single-pulse spot irradiation and multiple-pulse laser scanning irradiation in inducing cell death. Since the site of cell killing can be accurately chosen with a nanosecond pulse laser, this technique will help minimize damage to the cells around the target cells.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061173
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1174: PreOBP_ML: Machine Learning Algorithms
for Prediction of Optical Biosensor Parameters
Authors: Kawsar Ahmed, Francis M. Bui, Fang-Xiang Wu
First page: 1174
Abstract: To develop standard optical biosensors, the simulation procedure takes a lot of time. For reducing that enormous amount of time and effort, machine learning might be a better solution. Effective indices, core power, total power, and effective area are the most crucial parameters for evaluating optical sensors. In this study, several machine learning (ML) approaches have been applied to predict those parameters while considering the core radius, cladding radius, pitch, analyte, and wavelength as the input vectors. We have utilized least squares (LS), LASSO, Elastic-Net (ENet), and Bayesian ridge regression (BRR) to make a comparative discussion using a balanced dataset obtained with the COMSOL Multiphysics simulation tool. Furthermore, a more extensive analysis of sensitivity, power fraction, and confinement loss is also demonstrated using the predicted and simulated data. The suggested models were also examined in terms of R2-score, mean average error (MAE), and mean squared error (MSE), with all of the models having an R2-score of more than 0.99, and it was also shown that optical biosensors had a design error rate of less than 3%. This research might pave the way for machine learning-based optimization approaches to be used to improve optical biosensors.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061174
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1175: Simulation of a Fully Digital
Computing-in-Memory for Non-Volatile Memory for Artificial Intelligence
Edge Applications
Authors: Hongyang Hu, Chuancai Feng, Haiyang Zhou, Danian Dong, Xiaoshan Pan, Xiwei Wang, Lu Zhang, Shuaiqi Cheng, Wan Pang, Jing Liu
First page: 1175
Abstract: In recent years, digital computing in memory (CIM) has been an efficient and high-performance solution in artificial intelligence (AI) edge inference. Nevertheless, digital CIM based on non-volatile memory (NVM) is less discussed for the sophisticated intrinsic physical and electrical behavior of non-volatile devices. In this paper, we propose a fully digital non-volatile CIM (DNV-CIM) macro with compressed coding look-up table (LUT) multiplier (CCLUTM) using the 40 nm technology, which is highly compatible with the standard commodity NOR Flash memory. We also provide a continuous accumulation scheme for machine learning applications. When applied to a modified ResNet18 network trained under the CIFAR-10 dataset, the simulations indicate that the proposed CCLUTM-based DNV-CIM can achieve a peak energy efficiency of 75.18 TOPS/W with 4-bit multiplication and accumulation (MAC) operations.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061175
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1176: Phase-Optimized Multi-Step Phase
Acoustic Metasurfaces for Arbitrary Multifocal Beamforming
Authors: Jianxin Zhao, Xiongwei Wei, Chunlong Fei, Yi Li, Zhaoxi Li, Lifei Lou, Yi Quan, Yintang Yang
First page: 1176
Abstract: Focused ultrasound featuring non-destructive and high sensitivity has attracted widespread attention in biomedical and industrial evaluation. However, most traditional focusing techniques focus on the design and improvement of single-point focusing, neglecting the need to carry more dimensions of multifocal beams. Here we propose an automatic multifocal beamforming method, which is implemented using a four-step phase metasurface. The metasurface composed of four-step phases improves the transmission efficiency of acoustic waves as a matching layer and enhances the focusing efficiency at the target focal position. The change in the number of focused beams does not affect the full width at half maximum (FWHM), revealing the flexibility of the arbitrary multifocal beamforming method. Phase-optimized hybrid lenses reduce the sidelobe amplitude, and excellent agreement is observed between the simulation and experiments for triple-focusing beamforming metasurface lenses. The particle trapping experiment further validates the profile of the triple-focusing beam. The proposed hybrid lens can achieve flexible focusing in three dimensions (3D) and arbitrary multipoint, which may have potential prospects for biomedical imaging, acoustic tweezers, and brain neural modulation.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061176
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1177: A New Dual-Mass MEMS Gyroscope Fault
Diagnosis Platform
Authors: Rang Cui, Tiancheng Ma, Wenjie Zhang, Min Zhang, Longkang Chang, Ziyuan Wang, Jingzehua Xu, Wei Wei, Huiliang Cao
First page: 1177
Abstract: MEMS gyroscopes are one of the core components of inertial navigation systems. The maintenance of high reliability is critical for ensuring the stable operation of the gyroscope. Considering the production cost of gyroscopes and the inconvenience of obtaining a fault dataset, in this study, a self-feedback development framework is proposed, in which a dualmass MEMS gyroscope fault diagnosis platform is designed based on MATLAB/Simulink simulation, data feature extraction, and classification prediction algorithm and real data feedback verification. The platform integrates the dualmass MEMS gyroscope Simulink structure model and the measurement and control system, and reserves various algorithm interfaces for users to independently program, which can effectively identify and classify seven kinds of signals of the gyroscope: normal, bias, blocking, drift, multiplicity, cycle and internal fault. After feature extraction, six algorithms, ELM, SVM, KNN, NB, NN, and DTA, were respectively used for classification prediction. The ELM and SVM algorithms had the best effect, and the accuracy of the test set was up to 92.86%. Finally, the ELM algorithm is used to verify the actual drift fault dataset, and all of them are successfully identified.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061177
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1178: Humidity-Sensing Mattress for
Long-Term Bedridden Patients with Incontinence-Associated Dermatitis
Authors: Jinpitcha Mamom, Phadungsak Ratanadecho, Chatchai Mingmalairak, Bunyong Rungroungdouyboon
First page: 1178
Abstract: Designing new medical devices with advanced humidity sensors is of great significance for patients with incontinence-associated dermatitis (IAD). The primary goal of this study is to test the humidity-sensing mattress system for patients with IAD in clinical settings. The design of the mattress is set at 203 cm, with 10 × 3 sensors, dimensions of 19 × 32 cm, and a weighted bearing of 200 kg. The main sensors consist of a humidity-sensing film, a thin-film electrode (6 × 0.1 mm), and a glass substrate (500 nm). The sensitivity of the test mattress system showed that the resistance-humidity sensor was at a temperature of 35 °C (V0 = 30 V, V0 = 350 mV), with slope at 1.13 V/fF, f = 1 MHz, 20–90% RH, and a response time of 20 s at 2 μm. In addition, the humidity sensor reached 90% RH, with a response time of less than 10 s, a magnitude of 107–104 Ω, 1 mol%, CrO1.5, and FO1.5, respectively. This design is not only a simple, low-cost medical sensing device, but also opens a new pathway for developing humidity-sensing mattresses in the field of flexible sensors, wearable medical diagnostic devices, and health detection.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061178
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1179: Comparison of Circular and
Rectangular-Shaped Electrodes for Electrical Impedance Myography
Measurements on Human Upper Arms
Authors: Mohammad A. Ahad, Somen Baidya, Md. Nurul Tarek
First page: 1179
Abstract: Electrical Impedance Myography (EIM) is a painless, noninvasive approach for assessing muscle conditions through the application of a high-frequency, low-intensity current to the muscle region of interest. However, besides muscle properties, EIM measurements vary significantly with changes in some other anatomical properties such as subcutaneous skin-fat (SF) thickness and muscle girth, as well as non-anatomical factors, such as ambient temperature, electrode shape, inter-electrode distance, etc. This study has been conducted to compare the effects of different electrode shapes in EIM experiments, and to propose an acceptable configuration that is less dependent on factors other than the cellular properties of the muscle. Initially, a finite element model with two different kinds of electrode shapes, namely, rectangular (the conventional shape) and circular (the proposed shape) was designed for a subcutaneous fat thickness ranging from 5 mm to 25 mm. The study concludes, based on the FEM study, that replacing the conventional electrodes with our proposed electrodes can decrease the variation in EIM parameters due to changes in skin-fat thickness by 31.92%. EIM experiments on human subjects with these two kinds of electrode shapes validate our finite element simulation results, and show that circular electrodes can improve EIM effectiveness significantly, irrespective of muscle shape variation.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061179
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1180: Modeling and Validation of Total
Ionizing Dose Effect on the TSVs in RF Microsystem
Authors: Lihong Yang, Zhumeng Li, Guangbao Shan, Qijun Lu, Yu Fu
First page: 1180
Abstract: Radio frequency (RF) systems utilizing through-silicon vias (TSVs) have been widely used in the aerospace and nuclear industry, which means that studying the total ionizing dose (TID) effect on TSV structures has become necessary. To investigate the TID effect on TSV structures, a 1D TSV capacitance model was established in COMSOL Multiphysics (COMSOL), and the impact of irradiation was simulated. Then, three types of TSV components were designed, and an irradiation experiment based on them was conducted, to validate the simulation results. After irradiation, the S21 degraded for 0.2 dB, 0.6 dB, and 0.8 dB, at the irradiation dose of 30 krad (Si), 90 krad (Si), 150 krad (Si), respectively. The variation trend was consistent with the simulation in the high-frequency structure simulator (HFSS), and the effect of irradiation on the TSV component was nonlinear. With the increase in the irradiation dose, the S21 of TSV components deteriorated, while the variation of S21 decreased. The simulation and irradiation experiment validated a relatively accurate method for assessing the RF systems’ performance under an irradiation environment, and the TID effect on structures similar to TSVs in RF systems, such as through-silicon capacitors.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061180
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1181: Microrobot Path Planning Based on the
Multi-Module DWA Method in Crossing Dense Obstacle Scenario
Authors: Dequan Zeng, Haotian Chen, Yinquan Yu, Yiming Hu, Zhenwen Deng, Peizhi Zhang, Dongfu Xie
First page: 1181
Abstract: A hard issue in the field of microrobots is path planning in complicated situations with dense obstacle distribution. Although the Dynamic Window Approach (DWA) is a good obstacle avoidance planning algorithm, it struggles to adapt to complex situations and has a low success rate when planning in densely populated obstacle locations. This paper suggests a multi-module enhanced DWA (MEDWA) obstacle avoidance planning algorithm to address the aforementioned issues. An obstacle-dense area judgment approach is initially presented by combining Mahalanobis distance, Frobenius norm, and covariance matrix on the basis of a multi-obstacle coverage model. Second, MEDWA is a hybrid of enhanced DWA (EDWA) algorithms in non-dense areas with a class of two-dimensional analytic vector field methods developed in dense areas. The vector field methods are used instead of the DWA algorithms with poor planning performance in dense areas, which greatly improves the passing ability of microrobots over dense obstacles. The core of EDWA is to extend the new navigation function by modifying the original evaluation function and dynamically adjusting the weights of the trajectory evaluation function in different modules using the improved immune algorithm (IIA), thus improving the adaptability of the algorithm to different scenarios and achieving trajectory optimization. Finally, two scenarios with different obstacle-dense area locations were constructed to test the proposed method 1000 times, and the performance of the algorithm was verified in terms of step number, trajectory length, heading angle deviation, and path deviation. The findings indicate that the method has a smaller planning deviation and that the length of the trajectory and the number of steps can both be reduced by about 15%. This improves the ability of the microrobot to pass through obstacle-dense areas while successfully preventing the phenomenon of microrobots going around or even colliding with obstacles outside of dense areas.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061181
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1182: Development and Characterization of
Multi-Alkali Antimonide Photocathodes for High-Brightness RF
Photoinjectors
Authors: Sandeep Kumar Mohanty, Mikhail Krasilnikov, Anne Oppelt, Frank Stephan, Daniele Sertore, Laura Monaco, Carlo Pagani, Wolfgang Hillert
First page: 1182
Abstract: Due to their excellent photoemissive properties, especially low thermal emittance and high sensitivity in the green wavelength, multi-alkali antimonide photocathodes, in particular, cesium–potassium–antimonide, emerged as prominent photoemissive materials for the electron sources of high-repetition-rate FEL applications. To explore its feasibility of operating in a high-gradient RF gun, DESY collaborated with INFN LASA to develop multi-alkali photocathode materials. In this report, we describe the recipe of K-Cs-Sb photocathodes, which were grown on a Mo substrate by varying the foundational Sb layer thickness using sequential deposition techniques. This report also illustrates the information regarding the film thickness, substrate temperature, deposition rate, and its possible effects on the photocathode’s properties. In addition, the influence of temperature on the cathode degradation is also summarized. Furthermore, in the framework of density functional theory (DFT), we investigated the electronic and optical properties of the K₂CsSb material. The optical properties, such as dielectric function, reflectivity, refracting index, and extinction coefficient, were evaluated. The correlation between the calculated and measured optical properties, such as reflectivity, provides a better and more efficient strategy to rationalize and understand the photoemissive material’s properties.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061182
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1183: AlGaN/GaN Metal Oxide Semiconductor
High-Electron Mobility Transistors with Annealed TiO2 as Passivation and
Dielectric Layers
Authors: Yu-Shyan Lin, Chi-Che Lu
First page: 1183
Abstract: This paper reports on improved AlGaN/GaN metal oxide semiconductor high-electron mobility transistors (MOS-HEMTs). TiO2 is used to form the dielectric and passivation layers. The TiO2 film is characterized using X-ray photoemission spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM). The quality of the gate oxide is improved by annealing at 300 °C in N2. Experimental results indicate that the annealed MOS structure effectively reduces the gate leakage current. The high performance of the annealed MOS-HEMTs and their stable operation at elevated temperatures up to 450 K is demonstrated. Furthermore, annealing improves their output power characteristics.
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061183
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1184: A 17.8–20.2 GHz Compact
Vector-Sum Phase Shifter in 130 nm SiGe BiCMOS Technology for LEO Gateways
Receivers
Authors: Javier del Pino, Sunil L. Khemchandani, Mario San-Miguel-Montesdeoca, Sergio Mateos-Angulo, Daniel Mayor-Duarte, Jose Luis Saiz-Perez, David Galante-Sempere
First page: 1184
Abstract: This paper presents a novel and compact vector modulator (VM) architecture implemented in 130 nm SiGe BiCMOS technology. The design is suitable for use in receive phased arrays for the gateways of major low Earth orbit (LEO) constellations that operate in the 17.8 to 20.2 GHz frequency range. The proposed architecture uses four variable gain amplifiers (VGA) that are active at any given time and are switched to generate the four quadrants. Compared to conventional architectures, this structure is more compact and produces double the output amplitude. The design offers 6-bit phase control for 360°, and the total root mean square (RMS) phase and gain errors are 2.36° and 1.46 dB, respectively. The design occupies an area of 1309.4 μm × 1783.8 μm (including pads).
Citation: Micromachines
PubDate: 2023-05-31
DOI: 10.3390/mi14061184
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1185: Advanced Theranostic Strategies for
Viral Hepatitis Using Carbon Nanostructures
Authors: Ahmad Gholami, Seyyed Mojtaba Mousavi, Reza Masoumzadeh, Mojtaba Binazadeh, Kamran Bagheri Lankarani, Navid Omidifar, Omid Arjmand, Wei-Hung Chiang, Mohsen Moghadami, Nelson Pynadathu Rumjit
First page: 1185
Abstract: There are several treatment protocols for acute viral hepatitis, and it is critical to recognize acute hepatitis in its earliest stages. Public health measures to control these infections also rely on rapid and accurate diagnosis. The diagnosis of viral hepatitis remains expensive, and there is no adequate public health infrastructure, while the virus is not well-controlled. New methods for screening and detecting viral hepatitis through nanotechnology are being developed. Nanotechnology significantly reduces the cost of screening. In this review, the potential of three-dimensional-nanostructured carbon substances as promising materials due to fewer side effects, and the contribution of these particles to effective tissue transfer in the treatment and diagnosis of hepatitis due to the importance of rapid diagnosis for successful treatment, were extensively investigated. In recent years, three-dimensional carbon nanomaterials such as graphene oxide and nanotubes with special chemical, electrical, and optical properties have been used for the diagnosis and treatment of hepatitis due to their high potential. We expect that the future position of nanoparticles in the rapid diagnosis and treatment of viral hepatitis can be better determined.
Citation: Micromachines
PubDate: 2023-06-01
DOI: 10.3390/mi14061185
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1186: Detection of HER-3 with an
AlGaN/GaN-Based Ion-Sensitive Heterostructure Field Effect Transistor
Biosensor
Authors: Fengge Wang, Honghui Liu, Yanyan Xu, Zhiwen Liang, Zhisheng Wu, Yang Liu, Baijun Zhang
First page: 1186
Abstract: Human epidermal growth factor receptor-3 (HER-3) plays a key role in the growth and metastasis of cancer cells. The detection of HER-3 is very important for early screening and treatment of cancer. The AlGaN/GaN-based ion-sensitive heterostructure field effect transistor (ISHFET) is sensitive to surface charges. This makes it a promising candidate for the detection of HER-3. In this paper, we developed a biosensor for the detection of HER-3 with AlGaN/GaN-based ISHFET. The AlGaN/GaN-based ISHFET biosensor exhibits a sensitivity of 0.53 ± 0.04 mA/dec in 0.01 M phosphate buffer saline (1× PBS) (pH = 7.4) solution with 4% bovine serum albumin (BSA) at a source and drain voltage of 2 V. The detection limit is 2 ng/mL. A higher sensitivity (2.20 ± 0.15 mA/dec) can be achieved in 1× PBS buffer solution at a source and drain voltage of 2 V. The AlGaN/GaN-based ISHFET biosensor can be used for micro-liter (5 μL) solution measurements and the measurement can be performed after incubation of 5 min.
Citation: Micromachines
PubDate: 2023-06-01
DOI: 10.3390/mi14061186
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1187: Mechanical Response of MEMS Suspended
Inductors under Shock Using the Transfer Matrix Method
Authors: Tianxiang Zheng, Lixin Xu
First page: 1187
Abstract: MEMS suspended inductors are susceptible to deformation under external forces, which can lead to the degradation of their electrical properties. The mechanical response of the inductor to a shock load is usually solved by a numerical method, such as the finite element method (FEM). In this paper, the transfer matrix method of linear multibody system (MSTMM) is used to solve the problem. The natural frequencies and mode shapes of the system are obtained first, then the dynamic response by modal superposition. The time and position of the maximum displacement response and the maximum Von Mises stress are determined theoretically and independently of the shock. Furthermore, the effects of shock amplitude and frequency on the response are discussed. These MSTMM results agree well with those determined using the FEM. We achieved an accurate analysis of the mechanical behaviors of the MEMS inductor under shock load.
Citation: Micromachines
PubDate: 2023-06-01
DOI: 10.3390/mi14061187
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1188: A Low-Noise Micromachined
Accelerometer with Reconfigurable Electrodes for Resonance Suppression
Authors: Zayed Ahmed, Charles Duruaku, Fatemeh Edalatfar, Mehrdad Moallem, Behraad Bahreyni
First page: 1188
Abstract: We present a high-performance capacitive accelerometer with a sub-µg noise limit and 1.2 kHz bandwidth for particle acceleration detection applications. The low noise of the accelerometer is achieved through a combination of device design optimization and operation under vacuum to reduce the effects of air damping. Operation under vacuum, however, causes amplification of signals around the resonance region, potentially resulting in incapacitating it through saturation of interface electronics or nonlinearities and even damage. The device has thus been designed with two sets of electrodes for high and low electrostatic coupling efficiency. During normal operation, the open-loop device utilizes its high-sensitivity electrodes to provide the best resolution. When a strong signal near resonance is detected, the electrodes with low sensitivity are used for signal monitoring, while the high-sensitivity electrodes are used to apply feedback signals efficiently. A closed-loop electrostatic feedback control architecture is designed to counteract the large displacements of the proof mass near resonance frequency. Therefore, the ability to reconfigure electrodes lets the device be used in high-sensitivity or high-resiliency modes. Several experiments were conducted with DC and AC excitation at different frequencies to verify the effectiveness of the control strategy. The results showed a ten-fold reduction of displacement at resonance in the closed-loop arrangement compared to the open-loop system with a quality factor of 120.
Citation: Micromachines
PubDate: 2023-06-02
DOI: 10.3390/mi14061188
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1189: Rapid Calibration of Nanoliter per
Second Flow Rate by Image Processing Technology
Authors: Jiawei Luo, Cheng Yang, Yan Shen
First page: 1189
Abstract: The need for high-precision microflow control is increasingly evident across various fields. For instance, microsatellites employed in gravitational wave detection require flow supply systems with a high accuracy of up to 0.1 nL/s to achieve on-orbit attitude control and orbit control. However, conventional flow sensors are unable to provide the necessary precision in the nanoliter per second range, and thus, alternative methods are required. In this study, we propose the use of image processing technology for rapid microflow calibration. Our method involves capturing images of the droplets at the outlet of the flow supply system to rapidly obtain the flow rate, and we used the gravimetric method to verify the accuracy of our approach. We conducted several microflow calibration experiments within the 1.5 nL/s range and demonstrated that image processing technology can achieve the desired accuracy of 0.1 nL/s while saving more than two-thirds of the time required to obtain the flow rate within an acceptable margin of error compared to the gravimetric method. Our study presents an efficient and innovative approach to addressing the challenges of measuring microflows with high precision, particularly in the nanoliter per second range, and has the potential for widespread applications in various fields.
Citation: Micromachines
PubDate: 2023-06-02
DOI: 10.3390/mi14061189
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1190: An Experimental Study of Dislocation
Dynamics in GaN
Authors: Eugene B. Yakimov, Yury O. Kulanchikov, Pavel S. Vergeles
First page: 1190
Abstract: The dynamics of dislocations introduced through indentation or scratching at room temperature into a few GaN layers that were grown using the HVPE, MOCVD and ELOG methods and had different dislocation densities were studied via the electron-beam-induced current and cathodoluminescence methods. The effects of thermal annealing and electron beam irradiation on dislocation generation and multiplication were investigated. It is shown that the Peierls barrier for dislocation glide in GaN is essentially lower than 1 eV; thus, it is mobile even at room temperature. It is shown that the mobility of a dislocation in the state-of-the-art GaN is not entirely determined by its intrinsic properties. Rather, two mechanisms may work simultaneously: overcoming the Peierls barrier and overcoming localized obstacles. The role of threading dislocations as effective obstacles for basal plane dislocation glide is demonstrated. It is shown that under low-energy electron beam irradiation, the activation energy for the dislocation glide decreases to a few tens of meV. Therefore, under e-beam irradiation, the dislocation movement is mainly controlled by overcoming localized obstacles.
Citation: Micromachines
PubDate: 2023-06-02
DOI: 10.3390/mi14061190
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1191: Au-TiO2-Coated Spectroscopy-Based
Human Teeth Disorder Detection Sensor: Design and Quantitative Analysis
Authors: Sumaiya Akhtar Mitu, Kawsar Ahmed, Francis M. Bui, Li Chen, Lassaad K. Smirani, Shobhit K. Patel, Vishal Sorathiya
First page: 1191
Abstract: Human tooth functionality is the most important for the human body to become fit and healthy. Due to the disease attacks in human teeth, parts may lead to different fatal diseases. A spectroscopy-based photonic crystal fiber (PCF) sensor was simulated and numerically analyzed for the detection of dental disorders in the human body. In this sensor structure, SF11 is used as the base material, gold (Au) is used as the plasmonic material, and TiO2 is used within the gold and sensing analyte layer, and the sensing medium for the analysis of the teeth parts is the aqueous solution. The maximum optical parameter values for the human tooth parts enamel, dentine, and cementum in terms of wavelength sensitivity and confinement loss were obtained as 28,948.69 nm/RIU and 0.00015 dB/m for enamel, 33,684.99 nm/RIU and 0.00028 dB/m, and 38,396.56 nm/RIU and 0.00087 dB/m, respectively. The sensor is more precisely defined by these high responses. The PCF-based sensor for tooth disorder detection is a relatively recent development. Due to its design flexibility, robustness, and wide bandwidth, its application area has been spreading out. The offered sensor can be used in the biological sensing area to identify problems with human teeth.
Citation: Micromachines
PubDate: 2023-06-02
DOI: 10.3390/mi14061191
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1192: A Miniaturized Piezo Stack Impact
Actuation Mechanism for Out-of-Plane Freely Moveable Masses
Authors: Matthias C. Wapler, Constantin Peter, Koustav Kanjilal, Ulrike Wallrabe
First page: 1192
Abstract: We present the prototype and analytical model of a miniaturized impact actuation mechanism, providing a fast out-of-plane displacement to accelerate objects against gravity, allowing for freely moving objects and hence for large displacements without the need for cantilevers. To achieve the necessary high speed, we chose a piezoelectric stack actuator driven by a high-current pulse generator, connected to a rigid support and a rigid three-point contact with the object. We describe this mechanism with a spring-mass model and compare various spheres with different masses and diameters and from different materials. As expected, we found that larger flight heights are achieved by harder spheres, achieving, e.g., approx. 3 mm displacement for a 3 mm steel sphere using a 3 × 3 × 2 mm3 piezo stack.
Citation: Micromachines
PubDate: 2023-06-03
DOI: 10.3390/mi14061192
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1193: Plasma Figure Correction Method Based
on Multiple Distributed Material Removal Functions
Authors: Xiang Wu, Bin Fan, Qiang Xin, Qian Luo, Junming Shao, Guohan Gao, Peiqi Jiao
First page: 1193
Abstract: In the process of plasma figure correction for a quartz sub-mirror, the plasma parallel removal process and ink masking layer are combined for the first time. A universal plasma figure correction method based on multiple distributed material removal functions is demonstrated, and its technological characteristics are analyzed. Through this method, the processing time is independent of the workpiece aperture, which saves time for the material removal function to scan along the trajectory. After seven iterations, the form error of the quartz element is converged from the initial figure error of ~114 nm RMS to a figure error of ~28 nm RMS, which shows the practical potential of the plasma figure correction method based on multiple distributed material removal functions in optical element manufacturing and the possibility of becoming a new stage process in the optical manufacturing chain.
Citation: Micromachines
PubDate: 2023-06-03
DOI: 10.3390/mi14061193
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1194: Effect of Microwave Irradiation on the
Dielectric Characteristics of Semi-Conductive Nanoparticle-Based
Nanofluids: Progress towards the Microwave Synthesis
Authors: S. Raja, G. Koperundevi, Muthusankar Eswaran
First page: 1194
Abstract: Studies on dispersing nanoparticles in base fluid to elevate its essential and critical properties have evolved significantly in the recent decade. Alongside the conventional dispersion techniques used for nanofluid synthesis, microwave energy at 2.4 GHz frequency is irradiated onto the nanofluids is experimented with in this study. The effect of microwave irradiation on the electrical and thermal properties of semi-conductive nanofluids (SNF) is investigated and presented in this article. Titanium dioxide and zinc oxide are the semi-conductive nanoparticles used for this study to synthesize the SNF, viz., titania nanofluid (TNF) and zinc nanofluid (ZNF). Flash and fire points are the thermal properties verified, and dielectric breakdown strength, dielectric constant (εr), and dielectric dissipation factor (tan δ) are the electrical properties verified in this study. AC breakdown voltage (BDV) of TNF and ZNF is improved by 16.78% and 11.25%, respectively, more than SNFs prepared without microwave irradiation. Results justify that the synergetic effect of stirring, sonication, and microwave irradiation in a rational sequence (microwave synthesis) exhibited better electrical and unaltered thermal properties. This microwave-applied nanofluid synthesis could be a simple and effective route to prepare the SNF with improved electrical properties.
Citation: Micromachines
PubDate: 2023-06-03
DOI: 10.3390/mi14061194
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1195: Effect of CuO Nanoparticles on the
Optical, Structural, and Electrical Properties in the PMMA/PVDF
Nanocomposite
Authors: Amira Ben Gouider Trabelsi, Ayman M. Mostafa, Fatemah H. Alkallas, W. B. Elsharkawy, Ameenah N. Al-Ahmadi, Hoda A. Ahmed, Sherif S. Nafee, Rami Adel Pashameah, Eman A. Mwafy
First page: 1195
Abstract: A polymeric nanocomposite film, composed of PMMA/PVDF and different amounts of CuO NPs, was successfully prepared using the casting method to enhance its electrical conductivity. Various techniques were employed to investigate their physicochemical properties. The addition of CuO NPs causes a noticeable difference in the intensities and locations of vibrational peaks in all bands, confirming the incorporation of CuO NPs inside the PVDF/PMMA. In addition, the broadening of the peak at 2θ = 20.6° becomes more intense with increasing amounts of CuO NPs, confirming the increase in the amorphous characteristic of PMMA/PVDF incorporated with CuO NPs in comparison with PMMA/PVDF. Furthermore, the image of the polymeric structure exhibits a smoother shape and interconnection of pore structure associated with spherical particles that agglomerate and give rise to a web-like organization that becomes a matrix. Increasing surface roughness is responsible for an increasing surface area. Moreover, the addition of CuO NPs in the PMMA/PVDF leads to a decrease in the energy band gap, and further increasing the additional amounts of CuO NPs causes the generation of localized states between the valence and conduction bands. Furthermore, the dielectric investigation shows an increase in the dielectric constant, dielectric loss, and electric conductivity, which may be an indication of an increase in the degree of disorder that confines the movement of charge carriers and demonstrates the creation of an interconnected percolating chain, enhancing its conductivity values compared with that without the incorporation of a matrix.
Citation: Micromachines
PubDate: 2023-06-04
DOI: 10.3390/mi14061195
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1196: A 12-Port MIMO Antenna System for
5G/WLAN Applications
Authors: Wenshi You, Zhonggen Wang, Wenyan Nie, Weidong Mu
First page: 1196
Abstract: In this paper, a 12-port MIMO antenna system for 5G/WLAN applications is proposed. The proposed antenna system consists of two types of antenna modules: an L-shaped antenna module covering the C-band (3.4–3.6 GHz) for 5G mobile applications and a folded monopole module for the 5G/WLAN mobile application band (4.5–5.9 GHz). Each two antennas form a pair, six pairs in total, forming a 12 × 12 MIMO antenna array, and the elements between the antenna pairs can achieve an isolation of 11 dB or more without additional decoupling structures. Experimental results show that the antenna can cover the 3.3–3.6 GHz and 4.5–5.9 GHz bands with an overall efficiency greater than 75% and an envelope correlation coefficient less than 0.04. Finally, the one-hand holding mode and two-hand holding mode are discussed to demonstrate their stability in practical applications, and the results show that they still exhibit good radiation and MIMO performance when operating in both modes.
Citation: Micromachines
PubDate: 2023-06-05
DOI: 10.3390/mi14061196
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1197: Fabrication of Silver Nanobowl Arrays
on Patterned Sapphire Substrate for Surface-Enhanced Raman Scattering
Authors: Yanzhao Pang, Mingliang Jin
First page: 1197
Abstract: The current article discusses surface-enhanced Raman spectroscopy (SERS) as a powerful technique for detecting molecules or ions by analyzing their molecular vibration signals for fingerprint peak recognition. We utilized a patterned sapphire substrate (PSS) featuring periodic micron cone arrays. Subsequently, we prepared a three-dimensional (3D) PSS-loaded regular Ag nanobowls (AgNBs) array using self-assembly and surface galvanic displacement reactions based on polystyrene (PS) nanospheres. The SERS performance and structure of the nanobowl arrays were optimized by manipulating the reaction time. We discovered that the PSS substrates featuring periodic patterns exhibited superior light-trapping effects compared to the planar substrates. The SERS performance of the prepared AgNBs-PSS substrates was tested under the optimized experimental parameters with 4-mercaptobenzoic acid (4-MBA) as the probe molecule, and the enhancement factor (EF) was calculated to be 8.96 × 104. Finite-difference time-domain (FDTD) simulations were conducted to explain that the AgNBs arrays’ hot spots were distributed at the bowl wall locations. Overall, the current research offers a potential route for developing high-performance, low-cost 3D SERS substrates.
Citation: Micromachines
PubDate: 2023-06-05
DOI: 10.3390/mi14061197
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1198: Design of 2 μm Low-Loss
Hollow-Core Anti-Resonant Fibers
Authors: Tianran Sun, Xinyang Su, Fanchao Meng, Zaining Wang, Jiale Song, Chenglong Zhang, Tianjia Xu, Yunhong Zhang, Huaiwei Zhang, Mengdi Cui, Yi Zheng
First page: 1198
Abstract: We systematically studied several of the most traditional hollow-core anti-resonant fiber (HC-ARF) structures, with the aim of achieving low confinement loss, single-mode performance, and high insensitivity to bending in the 2 µm band. Moreover, the propagation loss of fundamental mode (FM), higher-order mode (HOMs), and the higher-order mode extinction ratio (HOMER) under different geometric parameters were studied. Analysis showed that the confinement loss of the six-tube nodeless hollow-core anti-resonant fiber at 2 µm was 0.042 dB/km, and its higher-order mode extinction ratio was higher than 9000. At the same time, a confinement loss of 0.040 dB/km at 2 was is achieved in the five-tube nodeless hollow-core anti-resonant fiber, and its higher-order mode extinction ratio was higher than 2700.
Citation: Micromachines
PubDate: 2023-06-05
DOI: 10.3390/mi14061198
Issue No: Vol. 14, No. 6 (2023)
- Micromachines, Vol. 14, Pages 1199: A Multi-Scale Tool Orientation
Generation Method for Freeform Surface Machining with Bull-Nose Tool
Authors: Jieshi Dong, Jinming He, Song Liu, Neng Wan, Zhiyong Chang
First page: 1199
Abstract: Free-form surface parts are widely used in industries, and they consist of intricate 3D surfaces such as molds, impellers, and turbine blades that possess complex geometrical contours and demand high precision. Proper tool orientation is crucial for ensuring the efficiency and accuracy of five-axis computer numerical control (CNC) machining. Multi-scale methods have received much attention and have been widely used in various fields. They have been proven to be instrumental and can obtain fruitful outcomes. Ongoing research on multi-scale tool orientation generation methods, which aim to acquire tool orientations that satisfy both macro- and micro-scale requirements, is significantly important for improving the machining quality of workpiece surfaces. This paper proposes a multi-scale tool orientation generation method that considers both the machining strip width and roughness scales. This method also ensures a smooth tool orientation and avoids interference in the machining process. First, the correlation between the tool orientation and rotational axis is analyzed, and feasible area calculation and tool orientation adjustment methods are introduced. Then, the paper introduces the calculation method for machining strip widths on the macro-scale and the roughness calculation method on the micro-scale. Besides, tool orientation adjustment methods for both scales are proposed. Next, a multi-scale tool orientation generation method is developed to generate tool orientations that meet the macro- and micro-scale requirements. Finally, to verify the effectiveness of the proposed multi-scale tool orientation generation method, it is applied to the machining of a free-form surface. Experimental verification results have shown that the tool orientation generated by the proposed method can obtain the expected machining strip width and roughness, meeting both macro- and micro-scale requirements. Therefore, this method has significant potential for engineering applications.
Citation: Micromachines
PubDate: 2023-06-05
DOI: 10.3390/mi14061199
Issue No: Vol. 14, No. 6 (2023)
