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Micromachines, Volume 14, Issue 4 (April 2023) – 190 articles

Cover Story (view full-size image): Micromachined deformable mirrors are often assembled using adhesives to bond actuators to a compliant face sheet. A new approach to minimizing stresses induced by adhesive assembly involves moving the adhesive joints to the ends of slender posts that extend integrally from the face sheet. These graphics depict a mirror face sheet made using silicon-on-insulator wafers and deep reactive ion etching. The “Overview” graphic shows the 12 mm diameter, 10 µm thick face sheet as fabricated with 37 integral slender posts. Three graphics are scanning electron micrographs of a portion of the posts, face sheet, and rigid silicon frame. Two graphics are scanning electron micrographs of a single post integrally fabricated with the face sheet membrane and our design versions. View this paper
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10 pages, 2521 KiB  
Communication
A Novel Program Scheme for Z-Interference Improvement in 3D NAND Flash Memory
by Jianquan Jia, Lei Jin, Xinlei Jia and Kaikai You
Micromachines 2023, 14(4), 896; https://doi.org/10.3390/mi14040896 - 21 Apr 2023
Cited by 2 | Viewed by 1505
Abstract
With gate length (Lg) and gate spacing length (Ls) shrinkage, the cell-to-cell z-interference phenomenon is increasingly severe in 3D NAND charge-trap memory. It has become one of the key reliability concerns for 3D NAND cell scaling. In this work, z-interference mechanisms were investigated [...] Read more.
With gate length (Lg) and gate spacing length (Ls) shrinkage, the cell-to-cell z-interference phenomenon is increasingly severe in 3D NAND charge-trap memory. It has become one of the key reliability concerns for 3D NAND cell scaling. In this work, z-interference mechanisms were investigated in the programming operation with the aid of Technology Computer-Aided Design (TCAD) and silicon data verification. It was found that the inter-cell trapped charges are one of the factors causing z-interference after cell programming, and these trapped charges can be modulated during programming. Thus, a novel program scheme is proposed to suppress the z-interference by reducing the pass voltage (Vpass) of the adjacent cells during programming. As a result, the proposed scheme suppresses the Vth shift of 40.1% for erased cells with Lg/Ls = 31/20 nm. In addition, this work further analyzes the optimization and balance of program disturbance and z-interference with the scaling of cell Lg-Ls based on the proposed scheme. Full article
(This article belongs to the Special Issue Advances in Emerging Nonvolatile Memory, Volume II)
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33 pages, 7191 KiB  
Article
Development and Research of the Sensitive Element of the MEMS Gyroscope Manufactured Using SOI Technology
by Danil Naumenko, Alexey Tkachenko, Igor Lysenko and Andrey Kovalev
Micromachines 2023, 14(4), 895; https://doi.org/10.3390/mi14040895 - 21 Apr 2023
Cited by 1 | Viewed by 2048
Abstract
In this article, based on the developed methodology, the stages of designing the sensitive element of a microelectromechanical gyroscope with an open-loop structure are considered. This structure is intended for use in control units for mobile objects such as robots, mobile trolleys, etc. [...] Read more.
In this article, based on the developed methodology, the stages of designing the sensitive element of a microelectromechanical gyroscope with an open-loop structure are considered. This structure is intended for use in control units for mobile objects such as robots, mobile trolleys, etc. To quickly obtain a ready-made gyroscope, a specialized integrated circuit (SW6111) was selected, for the use of which the electronic part of the sensitive element of the microelectromechanical gyroscope was developed. The mechanical structure was also taken from a simple design. The simulation of the mathematical model was carried out in the MATLAB/Simulink software environment. The mechanical elements and the entire structure were calculated using finite element modeling with ANSYS MultiPhysics CAD tools. The developed sensitive element of the micromechanical gyroscope was manufactured using bulk micromachining technology−silicon-on-insulator−with a structural layer thickness equal to 50 μm. Experimental studies were carried out using a scanning electron microscope and a contact profilometer. Dynamic characteristics were measured using a Polytec MSA-500 microsystem analyzer. The manufactured structure has low topological deviations. Calculations and experiments showed fairly accurate results for the dynamic characteristics, with an error of less than 3% for the first iteration of the design. Full article
(This article belongs to the Special Issue Design, Fabrication and Testing of MEMS/NEMS, 2nd Edition)
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16 pages, 798 KiB  
Article
Full Solutions to Flow and Heat Transfer from Slip-Induced Microtube Shapes
by Mustafa Turkyilmazoglu and Faisal Z. Duraihem
Micromachines 2023, 14(4), 894; https://doi.org/10.3390/mi14040894 - 21 Apr 2023
Cited by 5 | Viewed by 1189
Abstract
The main concern of this paper is to introduce some new tubular shapes whose cross-sections result from the imposition of Navier’s velocity slip at the surface. A new family of pipes induced by the slip mechanism is thus discovered. The family is shown [...] Read more.
The main concern of this paper is to introduce some new tubular shapes whose cross-sections result from the imposition of Navier’s velocity slip at the surface. A new family of pipes induced by the slip mechanism is thus discovered. The family is shown to modify the traditional pipes with elliptical cross-sections in the absence of slip, and they partly resemble collapsible tubes. The velocity field through the new pipes is then analytically determined. Afterwards, the corresponding temperature field with a constant heat flux boundary is shown to be perturbed around the slip parameter, whose leading order is well known from the literature. The correction to this order is next evaluated analytically. The velocity and temperature fields are further discussed regarding such new shapes. More physical features, such as the wall shear stress, the centerline velocity, the slip velocity and the convective heat transfer are also studied in detail. From the solutions, it is observed that a circular pipe under the effect of a slip mechanism has the largest temperature and the lowest Nusselt number at the center of the modified pipe. The new pipes are thought to have engineering and practical value in the micromachining industry, besides offering new analytical solutions for the considered flow geometry. Full article
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26 pages, 9664 KiB  
Article
SiamHAS: Siamese Tracker with Hierarchical Attention Strategy for Aerial Tracking
by Faxue Liu, Jinghong Liu, Qiqi Chen, Xuan Wang and Chenglong Liu
Micromachines 2023, 14(4), 893; https://doi.org/10.3390/mi14040893 - 21 Apr 2023
Cited by 2 | Viewed by 1388
Abstract
For the Siamese network-based trackers utilizing modern deep feature extraction networks without taking full advantage of the different levels of features, tracking drift is prone to occur in aerial scenarios, such as target occlusion, scale variation, and low-resolution target tracking. Additionally, the accuracy [...] Read more.
For the Siamese network-based trackers utilizing modern deep feature extraction networks without taking full advantage of the different levels of features, tracking drift is prone to occur in aerial scenarios, such as target occlusion, scale variation, and low-resolution target tracking. Additionally, the accuracy is low in challenging scenarios of visual tracking, which is due to the imperfect utilization of features. To improve the performance of the existing Siamese tracker in the above-mentioned challenging scenes, we propose a Siamese tracker based on Transformer multi-level feature enhancement with a hierarchical attention strategy. The saliency of the extracted features is enhanced by the process of Transformer Multi-level Enhancement; the application of the hierarchical attention strategy makes the tracker adaptively notice the target region information and improve the tracking performance in challenging aerial scenarios. Meanwhile, we conducted extensive experiments and qualitative or quantitative discussions on UVA123, UAV20L, and OTB100 datasets. Finally, the experimental results show that our SiamHAS performs favorably against several state-of-the-art trackers in these challenging scenarios. Full article
(This article belongs to the Special Issue Machine-Learning-Assisted Sensors)
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14 pages, 5042 KiB  
Article
Simulation and Experimental Study of a Piezoelectric Stack Energy Harvester for Railway Track Vibrations
by Zhaowei Min, Chengwei Hou, Guangdong Sui, Xiaobiao Shan and Tao Xie
Micromachines 2023, 14(4), 892; https://doi.org/10.3390/mi14040892 - 21 Apr 2023
Cited by 2 | Viewed by 2156
Abstract
As one of the most important modes of transportation, the safety of running trains and railway tracks is significant. It is essential to power sensors that detect and track health in remote areas. The vibration energy of the track structure is enormous, stable, [...] Read more.
As one of the most important modes of transportation, the safety of running trains and railway tracks is significant. It is essential to power sensors that detect and track health in remote areas. The vibration energy of the track structure is enormous, stable, and not limited by weather factors such as the sun and wind. A new type of arch beam piezoelectric stack energy harvester for railway systems is studied in this paper. Through simulation analyses and experimental verification of the energy harvester, the influences of external resistance, load, pre-stress, and load frequency on the energy harvesting performance of the piezoelectric energy harvester are discussed. When the frequency is less than 6 Hz, the energy capture efficiency is greatly affected by the frequency. When the frequency exceeds 6 Hz, the frequency has little effect and the load dramatically affects the energy capture efficiency. The pre-stress has little effect on the energy capture efficiency, but there is an optimal value at 4.5 kN. The energy harvester has an output power of 193 mW, a weight of 912 g, and the energy density can reach 211.8 μW/g. These results can provide a reference for subsequent experiments in the actual environment. Full article
(This article belongs to the Special Issue Piezoelectric MEMS/NEMS—Materials, Devices, and Applications)
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15 pages, 8428 KiB  
Article
An Exploration of the Influence of Abrasive Water Jet Pressure on the Friction Signal Characteristics of Fixed Abrasive Lapping Quartz Glass Based on HHT
by Yanling Zheng, Zhao Zhang, Zhankui Wang, Minghua Pang, Lijie Ma and Jianxiu Su
Micromachines 2023, 14(4), 891; https://doi.org/10.3390/mi14040891 - 21 Apr 2023
Cited by 1 | Viewed by 1177
Abstract
Abrasive water jetting is an effective dressing method for a fixed abrasive pad (FAP) and can improve FAP machining efficiency and the impact of abrasive water jet (AWJ) pressure on the dressing effect; moreover, the machining state of FAP after dressing has not [...] Read more.
Abrasive water jetting is an effective dressing method for a fixed abrasive pad (FAP) and can improve FAP machining efficiency and the impact of abrasive water jet (AWJ) pressure on the dressing effect; moreover, the machining state of FAP after dressing has not been thoroughly studied. Therefore, in this study, the FAP was dressed by using AWJ under four pressures, and the dressed FAP was subjected to lapping experiments and tribological experiments. Through an analysis of the material removal rate, FAP surface topography, friction coefficient, and friction characteristic signal, the influence of AWJ pressure on the friction characteristic signal in FAP processing was studied. The outcomes show that the impact of the dressing on FAP rises and then falls as the AWJ pressure increases. The best dressing effect was observed when the AWJ pressure was 4 MPa. In addition, the maximum value of the marginal spectrum initially rises and then falls as the AWJ pressure increases. When the AWJ pressure was 4 MPa, the peak value of the marginal spectrum of the FAP that was dressed during processing was the largest. Full article
(This article belongs to the Special Issue Frontiers in Ultra-Precision Machining, Volume II)
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10 pages, 1563 KiB  
Article
Efficient Synthesis of a Schiff Base Copper(II) Complex Using a Microfluidic Device
by Masashi Kobayashi, Takashiro Akitsu, Masahiro Furuya, Tetsushi Sekiguchi, Shuichi Shoji, Takashi Tanii and Daiki Tanaka
Micromachines 2023, 14(4), 890; https://doi.org/10.3390/mi14040890 - 21 Apr 2023
Cited by 3 | Viewed by 1509
Abstract
The efficient synthesis of amino acid Schiff base copper(II) complexes using a microfluidic device was successfully achieved. Schiff bases and their complexes are remarkable compounds due to their high biological activity and catalytic function. Conventionally, products are synthesized under reaction conditions of 40 [...] Read more.
The efficient synthesis of amino acid Schiff base copper(II) complexes using a microfluidic device was successfully achieved. Schiff bases and their complexes are remarkable compounds due to their high biological activity and catalytic function. Conventionally, products are synthesized under reaction conditions of 40 °C for 4 h using a beaker-based method. However, in this paper, we propose using a microfluidic channel to enable quasi-instantaneous synthesis at room temperature (23 °C). The products were characterized using UV–Vis, FT–IR, and MS spectroscopy. The efficient generation of compounds using microfluidic channels has the potential to significantly contribute to the efficiency of drug discovery and material development due to high reactivity. Full article
(This article belongs to the Special Issue Micromachines for Chemical Process Intensification, 2nd Edition)
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26 pages, 8708 KiB  
Article
Design and Development of a Traveling Wave Ferro-Microfluidic Device and System Rig for Potential Magnetophoretic Cell Separation and Sorting in a Water-Based Ferrofluid
by Rodward L. Hewlin, Jr., Maegan Edwards and Christopher Schultz
Micromachines 2023, 14(4), 889; https://doi.org/10.3390/mi14040889 - 21 Apr 2023
Cited by 10 | Viewed by 1796
Abstract
The timely detection and diagnosis of diseases and accurate monitoring of specific genetic conditions require rapid and accurate separation, sorting, and direction of target cell types toward a sensor device surface. In that regard, cellular manipulation, separation, and sorting are progressively finding application [...] Read more.
The timely detection and diagnosis of diseases and accurate monitoring of specific genetic conditions require rapid and accurate separation, sorting, and direction of target cell types toward a sensor device surface. In that regard, cellular manipulation, separation, and sorting are progressively finding application potential within various bioassay applications such as medical disease diagnosis, pathogen detection, and medical testing. The aim of this paper is to present the design and development of a simple traveling wave ferro-microfluidic device and system rig purposed for the potential manipulation and magnetophoretic separation of cells in water-based ferrofluids. This paper details in full: (1) a method for tailoring cobalt ferrite nanoparticles for specific diameter size ranges (10–20 nm), (2) the development of a ferro-microfluidic device for potentially separating cells and magnetic nanoparticles, (3) the development of a water-based ferrofluid with magnetic nanoparticles and non-magnetic microparticles, and (4) the design and development of a system rig for producing the electric field within the ferro-microfluidic channel device for magnetizing and manipulating nonmagnetic particles in the ferro-microfluidic channel. The results reported in this work demonstrate a proof of concept for magnetophoretic manipulation and separation of magnetic and non-magnetic particles in a simple ferro-microfluidic device. This work is a design and proof-of-concept study. The design reported in this model is an improvement over existing magnetic excitation microfluidic system designs in that heat is efficiently removed from the circuit board to allow a range of input currents and frequencies to manipulate non-magnetic particles. Although this work did not analyze the separation of cells from magnetic particles, the results demonstrate that non-magnetic (surrogates for cellular materials) and magnetic entities can be separated and, in some cases, continuously pushed through the channel based on amperage, size, frequency, and electrode spacing. The results reported in this work establish that the developed ferro-microfluidic device may potentially be used as an effective platform for microparticle and cellular manipulation and sorting. Full article
(This article belongs to the Special Issue Microfluidic Device Fabrication and Cell Manipulation)
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14 pages, 41347 KiB  
Article
Hierarchical Design of CuO/Nickel–Cobalt–Sulfide Electrode by a Facile Two-Step Potentiostatic Deposition
by Sa Lv, Peiyu Geng, Yaodan Chi, Huan Wang, Xuefeng Chu, Yang Zhao, Boqi Wu, Wenshi Shang, Chao Wang, Jia Yang, Zhifei Cheng and Xiaotian Yang
Micromachines 2023, 14(4), 888; https://doi.org/10.3390/mi14040888 - 20 Apr 2023
Viewed by 1158
Abstract
Herein, a scalable electrodeposition strategy is proposed to achieve hierarchical CuO/nickel–cobalt–sulfide (NCS) electrodes using two-step potentiostatic deposition followed by high-temperature calcination. The introduction of CuO provides support for the further deposition of NSC to ensure a high load of active electrode materials, thus [...] Read more.
Herein, a scalable electrodeposition strategy is proposed to achieve hierarchical CuO/nickel–cobalt–sulfide (NCS) electrodes using two-step potentiostatic deposition followed by high-temperature calcination. The introduction of CuO provides support for the further deposition of NSC to ensure a high load of active electrode materials, thus generating more abundant active electrochemical sites. Meanwhile, dense deposited NSC nanosheets are connected to each other to form many chambers. Such a hierarchical electrode prompts a smooth and orderly transmission channel for electron transport, and reserves space for possible volume expansion during the electrochemical test process. As a result, the CuO/NCS electrode exhibits superior specific capacitance (Cs) of 4.26 F cm−2 at 20 mA cm−2 and remarkable coulombic efficiency of 96.37%. Furthermore, the cycle stability of the CuO/NCS electrode remains at 83.05% within 5000 cycles. The multistep electrodeposition strategy provides a basis and reference for the rational design of hierarchical electrodes to be applied in the field of energy storage. Full article
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14 pages, 3224 KiB  
Article
Numerical Investigation of Transient Breakdown Voltage Enhancement in SOI LDMOS by Using a Step P-Type Doping Buried Layer
by Xiaoming Yang, Taiqiang Cao, Xiaohua Zhang, Tianqian Li and Hang Luo
Micromachines 2023, 14(4), 887; https://doi.org/10.3390/mi14040887 - 20 Apr 2023
Viewed by 1314
Abstract
In this paper, the transient breakdown voltage (TrBV) of a silicon-on-insulator (SOI) laterally diffused metal-oxide-semiconductor (LDMOS) device was increased by introducing a step P-type doping buried layer (SPBL) below the buried oxide (BOX). Device simulation software MEDICI 0.13.2 was used to [...] Read more.
In this paper, the transient breakdown voltage (TrBV) of a silicon-on-insulator (SOI) laterally diffused metal-oxide-semiconductor (LDMOS) device was increased by introducing a step P-type doping buried layer (SPBL) below the buried oxide (BOX). Device simulation software MEDICI 0.13.2 was used to investigate the electrical characteristics of the new devices. When the device was turned off, the SPBL could enhance the reduced surface field (RESURF) effect and modulate the lateral electric field in the drift region to ensure that the surface electric field was evenly distributed, thus increasing the lateral breakdown voltage (BVlat). The enhancement of the RESURF effect while maintaining a high doping concentration in the drift region (Nd) in the SPBL SOI LDMOS resulted in a reduction in the substrate doping concentration (Psub) and an expansion of the substrate depletion layer. Therefore, the SPBL both improved the vertical breakdown voltage (BVver) and suppressed an increase in the specific on-resistance (Ron,sp). The results of simulations showed a 14.46% higher TrBV and a 46.25% lower Ron,sp for the SPBL SOI LDMOS compared to those of the SOI LDMOS. As the SPBL optimized the vertical electric field at the drain, the turn-off non-breakdown time (Tnonbv) of the SPBL SOI LDMOS was 65.64% longer than that of the SOI LDMOS. The SPBL SOI LDMOS also demonstrated that TrBV was 10% higher, Ron,sp was 37.74% lower, and Tnonbv was 10% longer than those of the double RESURF SOI LDMOS. Full article
(This article belongs to the Special Issue Power Semiconductor Devices and Applications)
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17 pages, 66881 KiB  
Article
Research on Configuration Design Optimization and Trajectory Planning of Manipulators for Precision Machining and Inspection of Large-Curvature and Large-Area Curved Surfaces
by Xiangyang Sun, Shuai He, Zhenbang Xu, Enyang Zhang and Yanhui Li
Micromachines 2023, 14(4), 886; https://doi.org/10.3390/mi14040886 - 20 Apr 2023
Viewed by 988
Abstract
In recent years, high-quality surfaces with large areas and curvatures have been increasingly used in engineering, but the precision machining and inspection of such surfaces is a particular challenge. Surface machining equipment needs to have a large working space, high flexibility, and motion [...] Read more.
In recent years, high-quality surfaces with large areas and curvatures have been increasingly used in engineering, but the precision machining and inspection of such surfaces is a particular challenge. Surface machining equipment needs to have a large working space, high flexibility, and motion accuracy to meet the demands of micron-scale precision machining. However, meeting these requirements may result in extremely large equipment sizes. To solve this problem, an eight-degree-of-freedom redundant manipulator with one linear and seven rotational joints is designed to assist in the machining described in this paper. The configuration parameters of the manipulator are optimized by an improved multi-objective particle swarm optimization algorithm to ensure that the working space of the manipulator completely covers the working surface and that the size of the manipulator is small. In order to improve the smoothness and accuracy of manipulator motion on large surface areas, an improved trajectory planning strategy for a redundant manipulator is proposed. The idea of the improved strategy is to pre-process the motion path first and then use a combination of the clamping weighted least-norm method and the gradient projection method to plan the trajectory, while adding a reverse planning step to solve the singularity problem. The resulting trajectories are smoother than those planned by the general method. The feasibility and practicality of the trajectory planning strategy are verified through simulation. Full article
(This article belongs to the Special Issue Advanced Manufacturing Technology and Systems, 2nd Edition)
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14 pages, 4413 KiB  
Article
An In-Situ Tester for Extracting Piezoresistive Coefficients
by Fengyang Li, Runze Yu and Dacheng Zhang
Micromachines 2023, 14(4), 885; https://doi.org/10.3390/mi14040885 - 20 Apr 2023
Viewed by 1134
Abstract
In this study, an electrostatic force-driven on-chip tester consisting of a mass with four guided cantilever beams was employed to extract the process-related bending stiffness and piezoresistive coefficient in-situ for the first time. The tester was manufactured using the standard bulk silicon piezoresistance [...] Read more.
In this study, an electrostatic force-driven on-chip tester consisting of a mass with four guided cantilever beams was employed to extract the process-related bending stiffness and piezoresistive coefficient in-situ for the first time. The tester was manufactured using the standard bulk silicon piezoresistance process of Peking University, and was tested on-chip without additional handling. In order to reduce the deviation from process effects, the process-related bending stiffness was first extracted as an intermediate value, namely, 3590.74 N/m, which is 1.66% lower than the theoretical value. Then, the value was used to extract the piezoresistive coefficient using a finite element method (FEM) simulation. The extracted piezoresistive coefficient was 9.851 × 10−10 Pa−1, which essentially matched the average piezoresistive coefficient of the computational model based on the doping profile we first proposed. Compared with traditional extraction methods, such as the four-point bending method, this test method is on-chip, achieving automatic loading and precise control of the driving force, so it has high reliability and repeatability. Because the tester is manufactured together with the MEMS device, it has the potential to be used for process quality evaluation and monitoring on MEMS sensor production lines. Full article
(This article belongs to the Topic MEMS Sensors and Resonators)
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11 pages, 7409 KiB  
Article
Creating Stretchable Electronics from Dual Layer Flex-PCB for Soft Robotic Cardiac Mapping Catheters
by Abdellatif Ait Lahcen, Alexandre Caprio, Weihow Hsue, Cory Tschabrunn, Christopher Liu, Bobak Mosadegh and Simon Dunham
Micromachines 2023, 14(4), 884; https://doi.org/10.3390/mi14040884 - 20 Apr 2023
Cited by 3 | Viewed by 1868
Abstract
The authors present in this study the development of a novel method for creating stretchable electronics from dual-layer flex printed circuit boards (flex-PCBs) as a platform for soft robotic sensor arrays (SRSAs) for cardiac voltage mapping applications. There is a crucial need for [...] Read more.
The authors present in this study the development of a novel method for creating stretchable electronics from dual-layer flex printed circuit boards (flex-PCBs) as a platform for soft robotic sensor arrays (SRSAs) for cardiac voltage mapping applications. There is a crucial need for devices that utilize multiple sensors and provide high performance signal acquisition for cardiac mapping. Previously, our group demonstrated how single-layer flex-PCB can be postprocessed to create a stretchable electronic sensing array. In this work, a detailed fabrication process for creating a dual-layer multielectrode flex-PCB SRSA is presented, along with relevant parameters to achieve optimal postprocessing with a laser cutter. The dual-layer flex-PCB SRSA’s ability to acquire electrical signals is demonstrated both in vitro as well as in vivo on a Leporine cardiac surface. These SRSAs could be extended into full-chamber cardiac mapping catheter applications. Our results show a significant contribution towards the scalable use of dual-layer flex-PCB for stretchable electronics. Full article
(This article belongs to the Special Issue Feature Papers of Micromachines in 'Engineering and Technology' 2023)
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19 pages, 8447 KiB  
Article
Metal-Chelating Self-Assembling Peptide Nanofiber Scaffolds for Modulation of Neuronal Cell Behavior
by Kenana Dayob, Aygul Zengin, Ruslan Garifullin, Mustafa O. Guler, Timur I. Abdullin, Abdulla Yergeshov, Diana V. Salakhieva, Hong Hanh Cong and Mohamed Zoughaib
Micromachines 2023, 14(4), 883; https://doi.org/10.3390/mi14040883 - 19 Apr 2023
Cited by 1 | Viewed by 2013
Abstract
Synthetic peptides are promising structural and functional components of bioactive and tissue-engineering scaffolds. Here, we demonstrate the design of self-assembling nanofiber scaffolds based on peptide amphiphile (PA) molecules containing multi-functional histidine residues with trace metal (TM) coordination ability. The self-assembly of PAs and [...] Read more.
Synthetic peptides are promising structural and functional components of bioactive and tissue-engineering scaffolds. Here, we demonstrate the design of self-assembling nanofiber scaffolds based on peptide amphiphile (PA) molecules containing multi-functional histidine residues with trace metal (TM) coordination ability. The self-assembly of PAs and characteristics of PA nanofiber scaffolds along with their interaction with Zn, Cu, and Mn essential microelements were studied. The effects of TM-activated PA scaffolds on mammalian cell behavior, reactive oxygen species (ROS), and glutathione levels were shown. The study reveals the ability of these scaffolds to modulate adhesion, proliferation, and morphological differentiation of neuronal PC-12 cells, suggesting a particular role of Mn(II) in cell-matrix interaction and neuritogenesis. The results provide a proof-of-concept for the development of histidine-functionalized peptide nanofiber scaffolds activated with ROS- and cell-modulating TMs to induce regenerative responses. Full article
(This article belongs to the Special Issue Biomaterials, Biodevices and Tissue Engineering)
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13 pages, 3750 KiB  
Article
A Single-Event-Hardened Scheme for Ring Oscillator Applied to Radiation-Resistant PLL Microsystems
by Qi Xiang, Hongxia Liu and Yulun Zhou
Micromachines 2023, 14(4), 882; https://doi.org/10.3390/mi14040882 - 19 Apr 2023
Viewed by 1175
Abstract
A voltage-controlled oscillator (VCO) is one of the key modules of the phase-locked loop (PLL) microsystem, and it is easy to bombard using high-energy particles in a radiation environment, resulting in the single-event effect. In order to improve the anti-radiation ability of the [...] Read more.
A voltage-controlled oscillator (VCO) is one of the key modules of the phase-locked loop (PLL) microsystem, and it is easy to bombard using high-energy particles in a radiation environment, resulting in the single-event effect. In order to improve the anti-radiation ability of the PLL microsystems used in the aerospace environment, a new voltage-controlled oscillator hardened circuit is proposed in this work. The circuit consists of delay cells with an unbiased differential series voltage switch logic structure with a tail current transistor. By reducing sensitive nodes and using the positive feedback of the loop, the recovery process of the VCO circuit to the single-event transient (SET) is reduced and accelerated, so as to reduce the sensitivity of the circuit to the single-event effect. The simulation results based on the SMIC 130 nm complementary metal–oxide–semiconductor (CMOS) process show that the maximum phase shift difference of the PLL with the hardened VCO is reduced by 53.5%, which shows that the hardened VCO structure can reduce the sensitivity of the PLL to the SET and improve the reliability of the PLL in the radiation environment. Full article
(This article belongs to the Section D1: Semiconductor Devices)
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29 pages, 3877 KiB  
Article
Finger-Actuated Micropump of Constant Flow Rate without Backflow
by NurFarrahain Nadia Ahmad, Nik Nazri Nik Ghazali, Ahmad Taufiq Abdul Rani, Mohammad Hafiz Othman, Chia Ching Kee, Prastika Krisma Jiwanti, Arturo Rodríguez-Gómez and Yew Hoong Wong
Micromachines 2023, 14(4), 881; https://doi.org/10.3390/mi14040881 - 19 Apr 2023
Cited by 2 | Viewed by 1885
Abstract
This paper presents a finger-actuated micropump with a consistent flow rate and no backflow. The fluid dynamics in interstitial fluid (ISF) extraction microfluidics are studied through analytical, simulation, and experimental methods. Head losses, pressure drop, diodocity, hydrogel swelling, criteria for hydrogel absorption, and [...] Read more.
This paper presents a finger-actuated micropump with a consistent flow rate and no backflow. The fluid dynamics in interstitial fluid (ISF) extraction microfluidics are studied through analytical, simulation, and experimental methods. Head losses, pressure drop, diodocity, hydrogel swelling, criteria for hydrogel absorption, and consistency flow rate are examined in order to access microfluidic performance. In terms of consistency, the experimental result revealed that after 20 s of duty cycles with full deformation on the flexible diaphragm, the output pressure became uniform and the flow rate remained at nearly constant levels of 2.2 μL/min. The flow rate discrepancy between the experimental and predicted flow rates is around 22%. In terms of diodicity, when the serpentine microchannel and hydrogel-assisted reservoir are added to the microfluidic system integration, the diodicity increases by 2% (Di = 1.48) and 34% (Di = 1.96), respectively, compared to when the Tesla integration (Di = 1.45) is used alone. A visual and experimentally weighted analysis finds no signs of backflow. These significant flow characteristics demonstrate their potential usage in many low-cost and portable microfluidic applications. Full article
(This article belongs to the Special Issue Micromachines for Chemical Process Intensification, 2nd Edition)
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18 pages, 12001 KiB  
Article
Near-Field Beam Training in Terahertz Communications with Hybrid Beamforming Architecture
by Yuxin Xie, Boyu Ning, Lingxiang Li and Zhi Chen
Micromachines 2023, 14(4), 880; https://doi.org/10.3390/mi14040880 - 19 Apr 2023
Viewed by 1251
Abstract
Terahertz (THz) communication has a large available bandwidth, which is expected to be deployed in future communication networks. As THz wave suffers from severe propagation loss in wireless transmission, we consider a THz near-field scenario where a base station (BS) is equipped with [...] Read more.
Terahertz (THz) communication has a large available bandwidth, which is expected to be deployed in future communication networks. As THz wave suffers from severe propagation loss in wireless transmission, we consider a THz near-field scenario where a base station (BS) is equipped with a large-scale antenna array with a low-cost hybrid beamforming architecture to serve mobile users nearby. However, the large-scale array and the user mobility incur difficulty in channel estimation. To tackle this issue, we propose a near-field beam training scheme that can align a beam to the user in a fast way by searching the codebook. Specifically, the BS employs a uniform circular array (UCA), and the radiation pattern of the beams in our proposed codebook appears as ellipsoids. To cover the serving zone with the minimum codebook size, we develop a near-field codebook by tangent arrangement approach (TAA). To reduce the time overhead, we leverage the hybrid beamforming architecture to realize multi-beam training concurrently since each RF chain can enable a codeword whose element has a constant magnitude. Numerical results validate that our proposed UCA near-field codebook achieves less time cost while achieving a comparable coverage performance compared to the conventional near-field codebook. Full article
(This article belongs to the Special Issue Wireless Transceiver Design for RF/MM Waves and THz Communication)
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18 pages, 4370 KiB  
Article
Automated Industrial Composite Fiber Orientation Inspection Using Attention-Based Normalized Deep Hough Network
by Yuanye Xu, Yinlong Zhang and Wei Liang
Micromachines 2023, 14(4), 879; https://doi.org/10.3390/mi14040879 - 19 Apr 2023
Viewed by 1379
Abstract
Fiber-reinforced composites (FRC) are widely used in various fields due to their excellent mechanical properties. The mechanical properties of FRC are significantly governed by the orientation of fibers in the composite. Automated visual inspection is the most promising method in measuring fiber orientation, [...] Read more.
Fiber-reinforced composites (FRC) are widely used in various fields due to their excellent mechanical properties. The mechanical properties of FRC are significantly governed by the orientation of fibers in the composite. Automated visual inspection is the most promising method in measuring fiber orientation, which utilizes image processing algorithms to analyze the texture images of FRC. The deep Hough Transform (DHT) is a powerful image processing method for automated visual inspection, as the “line-like” structures of the fiber texture in FRC can be efficiently detected. However, the DHT still suffers from sensitivity to background anomalies and longline segments anomalies, which leads to degraded performance of fiber orientation measurement. To reduce the sensitivity to background anomalies and longline segments anomalies, we introduce the deep Hough normalization. It normalizes the accumulated votes in the deep Hough space by the length of the corresponding line segment, making it easier for DHT to detect short, true “line-like” structures. To reduce the sensitivity to background anomalies, we design an attention-based deep Hough network (DHN) that integrates attention network and Hough network. The network effectively eliminates background anomalies, identifies important fiber regions, and detects their orientations in FRC images. To better investigate the fiber orientation measurement methods of FRC in real-world scenarios with various types of anomalies, three datasets have been established and our proposed method has been evaluated extensively on them. The experimental results and analysis prove that the proposed methods achieve the competitive performance against the state-of-the-art in F-measure, Mean Absolute Error (MAE), Root Mean Squared Error (RMSE). Full article
(This article belongs to the Special Issue Intelligent Precision Machining)
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12 pages, 2175 KiB  
Article
3D Bioprinting of an Endothelialized Liver Lobule-like Construct as a Tumor-Scale Drug Screening Platform
by Zicheng Fan, Xiaoyun Wei, Keke Chen, Ling Wang and Mingen Xu
Micromachines 2023, 14(4), 878; https://doi.org/10.3390/mi14040878 - 19 Apr 2023
Cited by 6 | Viewed by 1867
Abstract
3D cell culture models replicating the complexity of cell–cell interactions and biomimetic extracellular matrix (ECM) are novel approaches for studying liver cancer, including in vitro drug screening or disease mechanism investigation. Although there have been advancements in the production of 3D liver cancer [...] Read more.
3D cell culture models replicating the complexity of cell–cell interactions and biomimetic extracellular matrix (ECM) are novel approaches for studying liver cancer, including in vitro drug screening or disease mechanism investigation. Although there have been advancements in the production of 3D liver cancer models to serve as drug screening platforms, recreating the structural architecture and tumor-scale microenvironment of native liver tumors remains a challenge. Here, using the dot extrusion printing (DEP) technology reported in our previous work, we fabricated an endothelialized liver lobule-like construct by printing hepatocyte-laden methacryloyl gelatin (GelMA) hydrogel microbeads and HUVEC-laden gelatin microbeads. DEP technology enables hydrogel microbeads to be produced with precise positioning and adjustable scale, facilitating the construction of liver lobule-like structures. The vascular network was achieved by sacrificing the gelatin microbeads at 37 °C to allow HUVEC proliferation on the surface of the hepatocyte layer. Finally, we used the endothelialized liver lobule-like constructs for anti-cancer drug (Sorafenib) screening, and stronger drug resistance results were obtained when compared to either mono-cultured constructs or hepatocyte spheroids alone. The 3D liver cancer models presented here successfully recreate liver lobule-like morphology, and may have the potential to serve as a liver tumor-scale drug screening platform. Full article
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13 pages, 1437 KiB  
Review
Microfluidic Chips: Emerging Technologies for Adoptive Cell Immunotherapy
by Yishen Tian, Rong Hu, Guangshi Du and Na Xu
Micromachines 2023, 14(4), 877; https://doi.org/10.3390/mi14040877 - 19 Apr 2023
Cited by 3 | Viewed by 2028
Abstract
Adoptive cell therapy (ACT) is a personalized therapy that has shown great success in treating hematologic malignancies in clinic, and has also demonstrated potential applications for solid tumors. The process of ACT involves multiple steps, including the separation of desired cells from patient [...] Read more.
Adoptive cell therapy (ACT) is a personalized therapy that has shown great success in treating hematologic malignancies in clinic, and has also demonstrated potential applications for solid tumors. The process of ACT involves multiple steps, including the separation of desired cells from patient tissues, cell engineering by virus vector systems, and infusion back into patients after strict tests to guarantee the quality and safety of the products. ACT is an innovative medicine in development; however, the multi-step method is time-consuming and costly, and the preparation of the targeted adoptive cells remains a challenge. Microfluidic chips are a novel platform with the advantages of manipulating fluid in micro/nano scales, and have been developed for various biological research applications as well as ACT. The use of microfluidics to isolate, screen, and incubate cells in vitro has the advantages of high throughput, low cell damage, and fast amplification rates, which can greatly simplify ACT preparation steps and reduce costs. Moreover, the customizable microfluidic chips fit the personalized demands of ACT. In this mini-review, we describe the advantages and applications of microfluidic chips for cell sorting, cell screening, and cell culture in ACT compared to other existing methods. Finally, we discuss the challenges and potential outcomes of future microfluidics-related work in ACT. Full article
(This article belongs to the Special Issue Microfluidic Devices for Biomedical Applications)
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15 pages, 5498 KiB  
Article
Parameter Study on Force Curves of Assembled Electronic Components on Foils during Injection Overmolding Using Simulation
by Martin Hubmann, Mona Bakr, Jonas Groten, Martin Pletz, Jan Vanfleteren, Frederick Bossuyt, Behnam Madadnia and Barbara Stadlober
Micromachines 2023, 14(4), 876; https://doi.org/10.3390/mi14040876 - 19 Apr 2023
Cited by 2 | Viewed by 1441
Abstract
The integration of assembled foils in injection-molded parts is a challenging step. Such assembled foils typically comprise a plastic foil on which a circuit board is printed and electronic components are mounted. Those components can detach during overmolding when high pressures and shear [...] Read more.
The integration of assembled foils in injection-molded parts is a challenging step. Such assembled foils typically comprise a plastic foil on which a circuit board is printed and electronic components are mounted. Those components can detach during overmolding when high pressures and shear stresses prevail due to the injected viscous thermoplastic melt. Hence, the molding settings significantly impact such parts’ successful, damage-free manufacturing. In this paper, a virtual parameter study was performed using injection molding software in which 1206-sized components were overmolded in a plate mold using polycarbonate (PC). In addition, experimental injection molding tests of that design and shear and peel tests were made. The simulated forces increased with decreasing mold thickness and melt temperature and increasing injection speed. The calculated tangential forces in the initial stage of overmolding ranged from 1.3 N to 7.3 N, depending on the setting used. However, the experimental at room temperature-obtained shear forces at break were at least 22 N. Yet, detached components were present in most of the experimentally overmolded foils. Hence, the shear tests performed at room temperature can only provide limited information. In addition, there might be a peel-like load case during overmolding where the flexible foil might bend during overmolding. Full article
(This article belongs to the Special Issue Flexible and Wearable Sensors)
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17 pages, 5508 KiB  
Article
Design of Hybrid Beamforming System Based on Practical Circuit Parameter of 6-Bit Millimeter-Wave Phase Shifters
by Mohammed A. Alqaisei, Abdel-Fattah A. Sheta, Ibrahim Elshafiey and Majid Altamimi
Micromachines 2023, 14(4), 875; https://doi.org/10.3390/mi14040875 - 19 Apr 2023
Viewed by 1402
Abstract
This paper addresses the design of a hybrid beamforming system considering the circuit parameter of six-bit millimeter-wave phase shifters based on the process design kit. The phase shifter design adopts 45 nm CMOS silicon on insulator (SOI) technology at 28-GHz. Various circuit topologies [...] Read more.
This paper addresses the design of a hybrid beamforming system considering the circuit parameter of six-bit millimeter-wave phase shifters based on the process design kit. The phase shifter design adopts 45 nm CMOS silicon on insulator (SOI) technology at 28-GHz. Various circuit topologies are utilized, and in particular, a design is presented based on switched LC components, connected in a cascode manner. The phase shifter configuration is connected in a cascading manner to get the 6-bit phase controls. Six different phase shifters are obtained, which are 180°, 90°, 45°, 22.5°, 11.25°, and 5.6°, with a minimum number of LC components. The circuit parameters of the designed phase shifters are then incorporated in a simulation model of hybrid beamforming for a multiuser MIMO system. The number of OFDM data symbols used in the simulation is ten for eight users, 16 QAM modulation schemes, −25 dB SNR, 120 simulation runs, and around 170 h runtime. Simulation results are obtained considering four and eight users, assuming accurate technology-based models of RFIC components of the phase shifter as well as ideal phase shifter parameters. The results indicate that the performance of the multiuser MIMO system is affected by the accuracy level of the phase shifter RF component models. The outcomes also reveal the performance tradeoff based on user data streams and the number of BS antennas. By optimizing the amount of parallel data streams per user, higher data transmission rates are achieved, while maintaining acceptable error vector magnitude (EVM) values. In addition, stochastic analysis is conducted to investigate the distribution of the RMS EVM. The outcomes show that the best fitting of RMS EVM distribution of the actual and ideal phase shifters agreed with the log-logistic and logistic distributions, respectively. The obtained (mean, variance) values of the actual phase shifters based on accurate library models are (46.997, 481.36), and for ideal components the values are (36.47, 10.44). Full article
(This article belongs to the Special Issue Exploring the Potential of 5G and Millimeter-Wave Array Antennas)
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22 pages, 43289 KiB  
Article
Development of Split Ring Resonator Shaped Six Element 2 × 3 Multiple Input Multiple Output Antenna for the C/X/Ku/K Band Applications
by Meshari Alsharari, Vishal Sorathiya, Ammar Armghan, Kavan Dave and Khaled Aliqab
Micromachines 2023, 14(4), 874; https://doi.org/10.3390/mi14040874 - 19 Apr 2023
Cited by 2 | Viewed by 1559
Abstract
In this manuscript, we have numerically investigated and experimentally verified the six-element split ring resonator and circular patch-shaped multiple input, multiple output antenna operating in the 1–25 GHz band. MIMO antennas are analyzed in terms of several physical parameters, such as reflectance, gain, [...] Read more.
In this manuscript, we have numerically investigated and experimentally verified the six-element split ring resonator and circular patch-shaped multiple input, multiple output antenna operating in the 1–25 GHz band. MIMO antennas are analyzed in terms of several physical parameters, such as reflectance, gain, directivity, VSWR, and electric field distribution. The parameters of the MIMO antenna, for instance, the envelope correlation coefficient (ECC), channel capacity loss (CCL), the total active reflection coefficient (TARC), directivity gain (DG), and mean effective gain (MEG), are also investigated for identification of a suitable range of these parameters for multichannel transmission capacity. Ultrawideband operation at 10.83 GHz is possible for the theoretically designed and practically executed antenna with the return loss and gain values of −19 dB and −28 dBi, respectively. Overall, the antenna offers minimum return loss values of −32.74 dB for the operating band of 1.92 to 9.81 GHz with a bandwidth of 6.89 GHz. The antennas are also investigated in terms of a continuous ground patch and a scattered rectangular patch. The proposed results are highly applicable for the ultrawideband operating MIMO antenna application in satellite communication with C/X/Ku/K bands. Full article
(This article belongs to the Special Issue State-of-the-Art Antenna Technology for Wireless Communication System)
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10 pages, 5036 KiB  
Article
Low Switching Loss Built-In Diode of High-Voltage RC-IGBT with Shortened P+ Emitter
by Wei Wu, Yansong Li, Mingkang Yu, Chongbing Gao, Yulu Shu and Yong Chen
Micromachines 2023, 14(4), 873; https://doi.org/10.3390/mi14040873 - 19 Apr 2023
Cited by 1 | Viewed by 1509
Abstract
In this paper, a low switching loss built-in diode of a high-voltage reverse-conducting insulated gate bipolar transistor (RC-IGBT) is proposed without deteriorating IGBT characteristics. It features a particular shortened P+ emitter (SE) in the diode part of RC-IGBT. Firstly, the shortened P+ emitter [...] Read more.
In this paper, a low switching loss built-in diode of a high-voltage reverse-conducting insulated gate bipolar transistor (RC-IGBT) is proposed without deteriorating IGBT characteristics. It features a particular shortened P+ emitter (SE) in the diode part of RC-IGBT. Firstly, the shortened P+ emitter in the diode part can suppress the hole injection efficiency resulting in the reduced carriers extracted during the reverse recovery process. The peak of the reverse recovery current and switching loss of the built-in diode during reverse recovery is therefore lowered. Simulation results indicate that the diode’s reverse recovery loss of the proposed RC-IGBT is lowered by 20% compared with that of the conventional RC-IGBT. Secondly, the separate design of the P+ emitter prevents the performance of IGBT from deteriorating. Finally, the wafer process of the proposed RC-IGBT is almost the same as that of conventional RC-IGBT, which makes it a promising candidate for manufacturing. Full article
(This article belongs to the Special Issue Power Semiconductor Devices and Applications)
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14 pages, 6959 KiB  
Article
Mechanical and Thermal Properties of the High Thermal Conductivity Steel (HTCS) Additively Manufactured via Powder-Fed Direct Energy Deposition
by Jong-Youn Son, Ki-Yong Lee, Gwang-Yong Shin, Chang-Hwan Choi and Do-Sik Shim
Micromachines 2023, 14(4), 872; https://doi.org/10.3390/mi14040872 - 18 Apr 2023
Cited by 3 | Viewed by 1549
Abstract
High thermal conductivity steel (HTCS-150) is deposited onto non-heat-treated AISI H13 (N-H13) via powder-fed direct energy deposition (DED) based on the response surface methodology (RSM) to enhance the mechanical properties and thermal conductivity of N-H13, which is generally used as a hot-work tool [...] Read more.
High thermal conductivity steel (HTCS-150) is deposited onto non-heat-treated AISI H13 (N-H13) via powder-fed direct energy deposition (DED) based on the response surface methodology (RSM) to enhance the mechanical properties and thermal conductivity of N-H13, which is generally used as a hot-work tool steel. The main process parameters of the powder-fed DED are priorly optimized to minimize defects in the deposited regions and, therefore, to obtain homogeneous material properties. The deposited HTCS-150 is comprehensively evaluated through hardness, tensile, and wear tests at the different temperatures of 25, 200, 400, 600, and 800 °C. Compared to conventionally heat-treated (quenched and tempered) H13 (HT-H13), the hardness of the additively manufactured HTCS-150 slightly increases at 25 °C, whereas it does not show any significant difference above 200 °C. However, the HTCS-150 deposited on N-H13 shows a lower ultimate tensile strength and elongation than HT-H13 at all tested temperatures, and the deposition of the HTCS-150 on N-H13 enhances the ultimate tensile strength of N-H13. While the HTCS-150 does not show a significant difference in the wear rate below 400 °C compared to HT-H13, it shows a lower wear rate above 600 °C. The HTCS-150 reveals a higher thermal conductivity than the HT-H13 below 600 °C, whereas the behavior is reversed at 800 °C. The results suggest that the HTCS-150 additively manufactured via powder-fed direct energy deposition can enhance the mechanical and thermal properties of N-H13, including hardness, tensile strength, wear resistance, and thermal conductivity in a wide range of temperatures, often superior to those of HT-H13. Full article
(This article belongs to the Special Issue Laser Additive Manufacturing of Metallic Materials)
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17 pages, 9229 KiB  
Article
Influence of Aging Treatment Regimes on Microstructure and Mechanical Properties of Selective Laser Melted 17-4 PH Steel
by Dongdong Dong, Jiang Wang, Chaoyue Chen, Xuchang Tang, Yun Ye, Zhongming Ren, Shuo Yin, Zhenyu Yuan, Min Liu and Kesong Zhou
Micromachines 2023, 14(4), 871; https://doi.org/10.3390/mi14040871 - 18 Apr 2023
Cited by 2 | Viewed by 1401
Abstract
Aging is indispensable for balancing the strength and ductility of selective laser melted (SLM) precipitation hardening steels. This work investigated the influence of aging temperature and time on the microstructure and mechanical properties of SLM 17-4 PH steel. The 17-4 PH steel was [...] Read more.
Aging is indispensable for balancing the strength and ductility of selective laser melted (SLM) precipitation hardening steels. This work investigated the influence of aging temperature and time on the microstructure and mechanical properties of SLM 17-4 PH steel. The 17-4 PH steel was fabricated by SLM under a protective argon atmosphere (99.99 vol.%), then the microstructure and phase composition after different aging treatments were characterized via different advanced material characterization techniques, and the mechanical properties were systematically compared. Coarse martensite laths were observed in the aged samples compared with the as-built ones, regardless of the aging time and temperature. Increasing the aging temperature resulted in a larger grain size of the martensite lath and precipitation. The aging treatment induced the formation of the austenite phase with a face-centered cubic (FCC) structure. With prolonged aging treatment, the volume fraction of the austenite phase increased, which agreed with the EBSD phase mappings. The ultimate tensile strength (UTS) and yield strength gradually increased with increasing aging times at 482 °C. The UTS reached its peak value after aging for 3 h at 482 °C, which was similar to the trend of microhardness (i.e., UTS = 1353.4 MPa). However, the ductility of the SLM 17-4 PH steel decreased rapidly after aging treatment. This work reveals the influence of heat treatment on SLM 17-4 steel and proposes an optimal heat-treatment regime for the SLM high-performance steels. Full article
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10 pages, 4311 KiB  
Article
Efficient Photodegradation of Rhodamine B by Fiber-like Nitrogen-Doped TiO2/Ni(OH)2 Nanocomposite under Visible Light Irradiation
by Huan Wang, Mingxuan Dong, Baorui Shao, Yaodan Chi, Chao Wang, Sa Lv, Ran Duan, Boqi Wu and Xiaotian Yang
Micromachines 2023, 14(4), 870; https://doi.org/10.3390/mi14040870 - 18 Apr 2023
Viewed by 937
Abstract
N-TiO2/Ni(OH)2 nanofiber was successfully prepared by combining the electrospinning and solvothermal method. It has been found that under visible light irradiation, the as-obtained nanofiber exhibits excellent activity for the photodegradation of rhodamine B, and the average degradation rate reaches 3.1%/min [...] Read more.
N-TiO2/Ni(OH)2 nanofiber was successfully prepared by combining the electrospinning and solvothermal method. It has been found that under visible light irradiation, the as-obtained nanofiber exhibits excellent activity for the photodegradation of rhodamine B, and the average degradation rate reaches 3.1%/min−1. Further insight investigations reveal that such a high activity was mainly due to the heterostructure-induced increase in the charge transfer rate and separation efficiency. Full article
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12 pages, 9439 KiB  
Article
Research on a Method to Improve the Temperature Performance of an All-Silicon Accelerometer
by Guowen Liu, Yu Liu, Xiao Ma, Xuefeng Wang, Xudong Zheng and Zhonghe Jin
Micromachines 2023, 14(4), 869; https://doi.org/10.3390/mi14040869 - 18 Apr 2023
Cited by 3 | Viewed by 1039
Abstract
This paper presents a novel method for the performance of an all-silicon accelerometer by adjusting the ratio of the Si-SiO2 bonding area, and the Au-Si bonding area in the anchor zone, with the aim of eliminating stress in the anchor region. The [...] Read more.
This paper presents a novel method for the performance of an all-silicon accelerometer by adjusting the ratio of the Si-SiO2 bonding area, and the Au-Si bonding area in the anchor zone, with the aim of eliminating stress in the anchor region. The study includes the development of an accelerometer model and simulation analysis which demonstrates the stress maps of the accelerometer under different anchor–area ratios, which have a strong impact on the performance of the accelerometer. In practical applications, the deformation of the comb structure fixed by the anchor zone is influenced by the stress in the anchor region, causing a distorted nonlinear response signal. The simulation results demonstrate that when the area ratio of the Si-SiO2 anchor zone to the Au-Si anchor zone decreases to 0.5, the stress in the anchor zone decreases significantly. Experimental results reveal that the full-temperature stability of zero-bias is optimized from 133 μg to 46 μg when the anchor–zone ratio of the accelerometer decreases from 0.8 to 0.5. At the same time, the full-temperature stability of the scale factor is optimized from 87 ppm to 32 ppm. Furthermore, zero-bias full-temperature stability and scale factor full-temperature stability are improved by 34.6% and 36.8%, respectively. Full article
(This article belongs to the Special Issue MEMS Inertial Device)
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13 pages, 5168 KiB  
Article
Study of a Fluorescent System Based on the Naphthalene Derivative Fluorescent Probe Bound to Al3+
by Qiuping Li, Lei Ma, Jianyan Li, Lijuan Wang, Liansheng Yu, Yuehui Zhao and Yuguang Lv
Micromachines 2023, 14(4), 868; https://doi.org/10.3390/mi14040868 - 17 Apr 2023
Cited by 2 | Viewed by 1341
Abstract
The naphthalene derivative fluorescent probe F6 was synthesized and a 1 × 10−3 mol/L solution of Al3+ and other metals to be tested was prepared for the subsequent experiments. The Al3+ fluorescence system of the naphthalene derivative fluorescent probe F6 [...] Read more.
The naphthalene derivative fluorescent probe F6 was synthesized and a 1 × 10−3 mol/L solution of Al3+ and other metals to be tested was prepared for the subsequent experiments. The Al3+ fluorescence system of the naphthalene derivative fluorescent probe F6 was successfully constructed as demonstrated by fluorescence emission spectroscopy. The optimal time, temperature and pH of the reaction were investigated. The selectivity and anti-interference ability of the probe F6 for Al3+ were investigated by fluorescence spectroscopy in a methanol solution. The experiments showed that the probe has high selectivity and anti-interference ability for Al3+. The binding ratio of F6 to Al3+ was 2:1, and the binding constant was calculated to be 1.598 × 105 M−1. The possible mechanism of the binding of the two was speculated. Different concentrations of Al3+ were added to Panax Quinquefolium and Paeoniae Radix Alba. The results showed that the recoveries of Al3+ were 99.75–100.56% and 98.67–99.67%, respectively. The detection limit was 8.73 × 10−8 mol/L. The experiments demonstrated that the formed fluorescence system can be successfully adapted for the determination of Al3+ content in two Chinese herbal medicines, which has good practical application. Full article
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22 pages, 8218 KiB  
Article
Design of a Compact Analog Complex Correlator for Millimeter-Wave Radiation Temperature Measurement System
by Wangdong He, Anyong Hu, Chen Dong, Xi Chen, Jianhao Gong and Jungang Miao
Micromachines 2023, 14(4), 867; https://doi.org/10.3390/mi14040867 - 17 Apr 2023
Viewed by 1089
Abstract
Human body temperature is a fundamental physiological sign that reflects the state of physical health. It is important to achieve high-accuracy detection for non-contact human body temperature measurement. In this article, a Ka band (32 to 36 GHz) analog complex correlator using the [...] Read more.
Human body temperature is a fundamental physiological sign that reflects the state of physical health. It is important to achieve high-accuracy detection for non-contact human body temperature measurement. In this article, a Ka band (32 to 36 GHz) analog complex correlator using the integrated six-port chip is proposed, and a millimeter-wave thermometer system based on the designed correlator is completed for human body temperature measurement. The designed correlator utilizes the six-port technique to achieve large bandwidth and high sensitivity, and miniaturization of the correlator is achieved through an integrated six-port chip. By performing the single-frequency test and the broadband noise measurement on the correlator, we can determine that the dynamic range of input power of the correlator is −70 dBm to −35 dBm, and the correlation efficiency and equivalent bandwidth are 92.5% and 3.42 GHz, respectively. Moreover, the output of the correlator varies linearly with the input noise power, which reveals that the designed correlator is suitable for the field of human body temperature measurement. Then, a handheld thermometer system, with a size of 140 mm × 47 mm × 20 mm, is proposed using the designed correlator, and the measurement results show that the temperature sensitivity of the thermometer is less than 0.2 K. Full article
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