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Micromachines, Volume 14, Issue 2 (February 2023) – 263 articles

Cover Story (view full-size image): This brief proposes a signal-independent background calibration in pipeline-SAR ADCs with a convergence-accelerated technique. To achieve signal independence, an auxiliary capacitor array CA is introduced to pre-inject a pseudo-random noise (PN) in the sampling phase to cancel out the opposite PN injection of the calibrated capacitor in the conversion phase, and CA is also used to realize the D/A function of the calibrated capacitor in the conversion phase. Additionally, the first sub-ADC is designed with extended conversion bits to quantize its own residue after delivering the conversion bits required by the first stage. Afterwards, this result is provided to the calibration algorithm to reduce the signal component and accelerate convergence. View this paper
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13 pages, 4403 KiB  
Article
Spin Hall Effect of Double-Index Cylindrical Vector Beams in a Tight Focus
by Alexey A. Kovalev and Victor V. Kotlyar
Micromachines 2023, 14(2), 494; https://doi.org/10.3390/mi14020494 - 20 Feb 2023
Cited by 10 | Viewed by 1214
Abstract
We investigate the spin angular momentum (SAM) of double-index cylindrical vector beams in tight focus. Such a set of beams is a generalization of the conventional cylindrical vector beams since the polarization order is different for the different transverse field components. Based on [...] Read more.
We investigate the spin angular momentum (SAM) of double-index cylindrical vector beams in tight focus. Such a set of beams is a generalization of the conventional cylindrical vector beams since the polarization order is different for the different transverse field components. Based on the Richards-Wolf theory, we obtain an expression for the SAM distribution and show that if the polarization orders are of different parity, then the spin Hall effect occurs in the tight focus, which is there are alternating areas with positive and negative spin angular momentum, despite linear polarization of the initial field. We also analyze the orbital angular momentum spectrum of all the components of the focused light field and determine the overwhelming angular harmonics. Neglecting the weak harmonics, we predict the SAM distribution and demonstrate the ability to generate the focal distribution where the areas with the positive and negative spin angular momentum reside on a ring and are alternating in pairs, or separated in different semicircles. Application areas of the obtained results are designing micromachines with optically driven elements. Full article
(This article belongs to the Special Issue Feature Papers of Micromachines in Physics 2023)
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18 pages, 5785 KiB  
Article
Numerical Simulation Study of Multi-Field Coupling for Laser Cladding of Shaft Parts
by Changlong Zhao, Chen Ma, Junbao Yang, Ming Li, Qinxiang Zhao, Hongnan Ma and Xiaoyu Jia
Micromachines 2023, 14(2), 493; https://doi.org/10.3390/mi14020493 - 20 Feb 2023
Cited by 1 | Viewed by 1548
Abstract
Since shaft parts operate under harsh environments for a long time, many critical parts suffer from corrosion, wear and other problems, leading to part failure and inability to continue in service. It is imperative to repair failed parts and increase their service life. [...] Read more.
Since shaft parts operate under harsh environments for a long time, many critical parts suffer from corrosion, wear and other problems, leading to part failure and inability to continue in service. It is imperative to repair failed parts and increase their service life. An orthogonal experimental scheme is designed to numerically simulate the process of laser cladding of Inconel 718 alloy powder on 4140 alloy structural steel based on the ANSYS simulation platform, derive the relationship equation of cladding layer thickness according to the heat balance principle, establish a finite element model, couple three modules of temperature field, stress field and fluid field, and analyze different modules to realize the monitoring of different processes of laser cladding. The optimal cladding parameters were laser power 1000 W, scanning speed 15 rad/s, spot radius 1.5 mm, thermal stress maximum value of 696 Mpa, residual stress minimum value of 281 Mpa, and the degree of influence of three factors on thermal stress maximum value: laser power > spot radius > scanning speed. The pool in the melting process appears to melt the “sharp corner” phenomenon, the internal shows a double vortex effect, with a maximum flow rate of 0.02 m/s. The solidification process shows a different shape at each stage due to the different driving forces. In this paper, multi-field-coupled numerical simulations of the laser cladding process were performed to obtain optimal cladding parameters with low residual stresses in the clad layer. The melt pool grows and expands gradually during melting, but the laser loading time is limited, and the size and shape of the melt pool are eventually fixed, and there is a vortex flowing from the center to both sides of the cross-section inside the melt pool, forming a double vortex effect. The solidification is divided into four stages to complete the transformation of the liquid phase of the melt pool to the solid phase, and the cladding layer is formed. The multi-field-coupled numerical simulation technique is used to analyze the temperature, stress and fluid fields to provide a theoretical basis for the residual stress and surface quality of the clad layer for subsequent laser cladding experiments. Full article
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14 pages, 4806 KiB  
Article
Single-Cell Microarray Chip with Inverse-Tapered Wells to Maintain High Ratio of Cell Trapping
by Ryota Sano, Kentaro Koyama, Narumi Fukuoka, Hidetaka Ueno, Shohei Yamamura and Takaaki Suzuki
Micromachines 2023, 14(2), 492; https://doi.org/10.3390/mi14020492 - 20 Feb 2023
Cited by 1 | Viewed by 1459
Abstract
A single-cell microarray (SCM) influenced by gravitational force is expected to be one of the simple methods in various fields such as DNA analysis and antibody production. After trapping the cells in the SCM chip, it is necessary to remove the liquid from [...] Read more.
A single-cell microarray (SCM) influenced by gravitational force is expected to be one of the simple methods in various fields such as DNA analysis and antibody production. After trapping the cells in the SCM chip, it is necessary to remove the liquid from the SCM to wash away the un-trapped cells on the chip and treat the reagents for analysis. The flow generated during this liquid exchange causes the trapped cells to drop out of conventional vertical wells. In this study, we propose an inverse-tapered well to keep trapped cells from escaping from the SCM. The wells with tapered side walls have a reduced force of flow toward the opening, which prevents trapped cells from escaping. The proposed SCM chip was fabricated using 3D photolithography and polydimethylsiloxane molding techniques. In the trapping experiment using HeLa cells, the cell residual rate increased more than two-fold for the SCM chip with the inverse-tapered well with a taper angle of 30° compared to that for the conventional vertical SCM chip after multiple rounds of liquid exchanges. The proposed well structure increases the number of trapped cells and decreases the cell dropout rate to improve the efficiency of cellular analysis. Full article
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10 pages, 6266 KiB  
Article
Intelligent Device for Harvesting the Vibration Energy of the Automobile Exhaust with a Piezoelectric Generator
by Jie Huang, Cheng Xu, Nan Ma, Qinghui Zhou, Zhaohua Ji, Chunxia Jia, Shan Xiao and Peng Wang
Micromachines 2023, 14(2), 491; https://doi.org/10.3390/mi14020491 - 20 Feb 2023
Cited by 1 | Viewed by 1601
Abstract
With increasing consumption of energy and increasing environmental pollution, research on capturing the vibration energy lost during transportation and vehicle driving is growing rapidly. There is a large amount of vibration energy in the automobile exhaust system that can be recycled. This paper [...] Read more.
With increasing consumption of energy and increasing environmental pollution, research on capturing the vibration energy lost during transportation and vehicle driving is growing rapidly. There is a large amount of vibration energy in the automobile exhaust system that can be recycled. This paper proposes a self-powered intelligent device (SPID) using a piezoelectric energy generator. The SPID includes a piezoelectric generator and sensor unit, and the generator is installed at the end of the automobile exhaust system. The generator adopts a parallel structure of four piezoelectric power generation units, and the sensing unit comprises light-emitting diode warning lights or low-power sensors. A simulated excitation experiment verifies the working state and peak power of the piezoelectric generator unit, which can achieve 23.4 μW peak power. The self-power supply and signal monitoring functions of the intelligent device are verified in experiments conducted for driving light-emitting diode lights and low-power sensors. The device is expected to play a crucial role in the field of intelligent driving and automobile intelligence. Full article
(This article belongs to the Special Issue Recent Advance in Piezoelectric Actuators and Motors 2023)
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11 pages, 4208 KiB  
Article
Programmable UV-Curable Resin by Dielectric Force
by Yi-Wei Lin, Chang-Yi Chen, Ying-Fang Chang, Yii-Nuoh Chang and Da-Jeng Yao
Micromachines 2023, 14(2), 490; https://doi.org/10.3390/mi14020490 - 20 Feb 2023
Viewed by 1281
Abstract
In this study, UV-curable resin was formed into different patterns through the programmable control of dielectric force. The dielectric force is mainly generated by the dielectric chip formed by the interdigitated electrodes. This study observed that of the control factors affecting the size [...] Read more.
In this study, UV-curable resin was formed into different patterns through the programmable control of dielectric force. The dielectric force is mainly generated by the dielectric chip formed by the interdigitated electrodes. This study observed that of the control factors affecting the size of the UV resin driving area, current played an important role. We maintained the same voltage-controlled condition, changing the current from 0.1 A to 0.5 A as 0.1 A intervals. The area of droplets was significantly different at each current condition. On the other hand, we maintained the same current condition, and changed the voltage from 100 V to 300 V at 50 V intervals. The area of droplets for each voltage condition was not obviously different. The applied frequency of the AC (Alternating Current) electric field increased from 10 kHz to 50 kHz. After driving the UV resin, the pattern line width of the UV resin could be finely controlled from 224 um to 137 um. In order to form a specific pattern, controlling the current and frequency could achieved a more accurate shape. In this article, UV resin with different patterns was formed through the action of this dielectric force, and after UV curing, tiny structural parts could be successfully demonstrated. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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14 pages, 7603 KiB  
Article
Smart Cup for In-Situ 3D Measurement of Wall-Mounted Debris via 2D Sensing Grid in Production Pipelines
by Hao Tian, Sunyi Wang, Minglei Fu, Dayong Ning and Yongjun Gong
Micromachines 2023, 14(2), 489; https://doi.org/10.3390/mi14020489 - 19 Feb 2023
Viewed by 1279
Abstract
The accumulation of separated out impurities from pipeline transported medium onto the pipe wall is a major cause of downtime maintenance of oil and gas production systems. To regularly scrub off wall-mounted debris and probe the severity, pipeline inspection gauges (PIG) are the [...] Read more.
The accumulation of separated out impurities from pipeline transported medium onto the pipe wall is a major cause of downtime maintenance of oil and gas production systems. To regularly scrub off wall-mounted debris and probe the severity, pipeline inspection gauges (PIG) are the state-of-the-art tools developed for the task, using the pressure differential across the device as the driving force, and tag-along sensing equipment for wall defects measurement. Currently, the PIG propulsion and sensing tasks are realized by separate compartments, limited to large diameter operations. In this work, a soft solution for medium to small diameter pipelines has been demonstrated. The smart cup with integrated sensing grid is proposed to achieve integrated wall-mounted debris dimensional measurement, without the need of additional sensors. To achieve the goal, this work starts from the mathematical modelling of the geometric problem, to new fabrication procedures, experimental setup, and finally finishes with validation results. Initial results have shown that using the proposed smart cup, the wall-mounted debris can be detected, with modelling error maxed at 5.1%, and deformation detection accuracy between 1.18% and 1.92% with respect to the outer diameter. Full article
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11 pages, 4142 KiB  
Article
Structure Optimization of Planar Nanoscale Vacuum Channel Transistor
by Ji Xu, Congyuan Lin, Yu Li, Xueliang Zhao, Yongjiao Shi and Xiaobing Zhang
Micromachines 2023, 14(2), 488; https://doi.org/10.3390/mi14020488 - 19 Feb 2023
Cited by 2 | Viewed by 1595
Abstract
Due to its unique structure, discoveries in nanoscale vacuum channel transistors (NVCTs) have demonstrated novel vacuum nanoelectronics. In this paper, the structural parameters of planar-type NVCTs were simulated, which illustrated the influence of emitter tip morphology on emission performance. Based on simulations, we [...] Read more.
Due to its unique structure, discoveries in nanoscale vacuum channel transistors (NVCTs) have demonstrated novel vacuum nanoelectronics. In this paper, the structural parameters of planar-type NVCTs were simulated, which illustrated the influence of emitter tip morphology on emission performance. Based on simulations, we successfully fabricated back-gate and side-gate NVCTs, respectively. Furthermore, the electric properties of NVCTs were investigated, showing the potential to realize the high integration of vacuum transistors. Full article
(This article belongs to the Special Issue On-Chip Electron Emission and Related Devices)
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13 pages, 3625 KiB  
Article
Hierarchical NiMn-LDH Hollow Spheres as a Promising Pseudocapacitive Electrode for Supercapacitor Application
by Jai Kumar, Rana R. Neiber, Zaheer Abbas, Razium Ali Soomro, Amal BaQais, Mohammed A. Amin and Zeinhom M. El-Bahy
Micromachines 2023, 14(2), 487; https://doi.org/10.3390/mi14020487 - 19 Feb 2023
Cited by 5 | Viewed by 2283
Abstract
Layered double hydroxides (LDH) are regarded as attractive pseudocapacitive materials due to their impressive capacitive qualities that may be adjustable to their morphological features. However, the layered structure of LDH renders them susceptible to structural aggregation, which inhibits effective electrolyte transport and limits [...] Read more.
Layered double hydroxides (LDH) are regarded as attractive pseudocapacitive materials due to their impressive capacitive qualities that may be adjustable to their morphological features. However, the layered structure of LDH renders them susceptible to structural aggregation, which inhibits effective electrolyte transport and limits their practical applicability after limited exposure to active areas. Herein, we propose a simple template-free strategy to synthesize hierarchical hollow sphere NiMn-LDH material with high surface area and exposed active as anode material for supercapacitor application. The template-free approach enables the natural nucleation of Ni-Mn ions resulting in thin sheets that self-assemble into a hollow sphere, offering expended interlayer spaces and abundant redox-active active sites. The optimal NiMn-LDH-12 achieved a specific capacitance of 1010.4 F g−1 at a current density of 0.2 A g−1 with capacitance retention of 70% at 5 A g−1 after 5000 cycles with lower charge transfer impedance. When configured into an asymmetric supercapacitors (ASC) device as NiMn-LDH//AC, the material realized a specific capacitance of 192.4 F g−1 at a current density of 0.2 A g−1 with a good energy density of 47.9 Wh kg−1 and a power density of 196.8 W kg−1. The proposed morphological-tuning route is promising for designing template-free NiMn-LDHs spheres with practical pseudocapacitive characteristics. Full article
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12 pages, 3658 KiB  
Article
Beyond Memristors: Neuromorphic Computing Using Meminductors
by Frank Zhigang Wang
Micromachines 2023, 14(2), 486; https://doi.org/10.3390/mi14020486 - 19 Feb 2023
Cited by 1 | Viewed by 8386
Abstract
Resistors with memory (memristors), inductors with memory (meminductors) and capacitors with memory (memcapacitors) play different roles in novel computing architectures. We found that a coil with a magnetic core is an inductor with memory (meminductor) in terms of its inductance L(q [...] Read more.
Resistors with memory (memristors), inductors with memory (meminductors) and capacitors with memory (memcapacitors) play different roles in novel computing architectures. We found that a coil with a magnetic core is an inductor with memory (meminductor) in terms of its inductance L(q) being a function of charge q. The history of the current passing through the coil is remembered by the magnetization inside the magnetic core. Such a meminductor can play a unique role (that cannot be played by a memristor) in neuromorphic computing, deep learning and brain-inspired computers since the time constant (t0=LC) of a neuromorphic RLC circuit is jointly determined by the inductance L and capacitance C, rather than the resistance R. As an experimental verification, this newly invented meminductor was used to reproduce the observed biological behavior of amoebae (the memorizing, timing and anticipating mechanisms). In conclusion, a beyond-memristor computing paradigm is theoretically sensible and experimentally practical. Full article
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17 pages, 5571 KiB  
Article
Boosting the Electrostatic MEMS Converter Output Power by Applying Three Effective Performance-Enhancing Techniques
by Mona S. Salem, Abdelhalim Zekry, Mohamed Abouelatta, Ahmed Shaker, Marwa S. Salem, Christian Gontrand and Ahmed Saeed
Micromachines 2023, 14(2), 485; https://doi.org/10.3390/mi14020485 - 19 Feb 2023
Viewed by 1408
Abstract
This current study aims to enhance the electrostatic MEMS converter performance mainly by boosting its output power. Three different techniques are applied to accomplish such performance enhancement. Firstly, the power is boosted by scaling up the technology of the converter CMOS accompanied circuit, [...] Read more.
This current study aims to enhance the electrostatic MEMS converter performance mainly by boosting its output power. Three different techniques are applied to accomplish such performance enhancement. Firstly, the power is boosted by scaling up the technology of the converter CMOS accompanied circuit, the power conditioning, and power controlling circuits, from 0.35 µm to 0.6 µm CMOS technology. As the converter area is in the range of mm2, there are no restrictions concerning the scaling up of the accompanied converter CMOS circuits. As a result, the maximum voltage of the system for harvesting energy, Vmax, which is the most effective system constraint that greatly affects the converter’s output power, increases from 8 V to 30 V. The output power of the designed and simulated converter based on the 0.6 µm technology increases from 2.1 mW to 4.5 mW. Secondly, the converter power increases by optimizing its technological parameters, the converter thickness and the converter finger width and length. Such optimization causes the converter output power to increase from 4.5 mW to 11.2 mW. Finally, the converter structure is optimized to maximize its finger length by using its wasted shuttle mass area which does not contribute to its capacitances and output power. The proposed structure increases the converter output power from 11.2 mW to 14.29 mW. Thus, the three applied performance enhancement techniques boosted the converter output power by 12.19 mW, which is a considerable enhancement in the converter performance. All simulations are carried out using COMSOL Multiphysics 5.4. Full article
(This article belongs to the Topic MEMS Sensors and Resonators)
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9 pages, 3230 KiB  
Article
Predictions of the Wettable Parameters of an Axisymmetric Large-Volume Droplet on a Microstructured Surface in Gravity
by Jian Dong, Jianliang Hu, Zihao Zhang, Mengying Gong and Zhixin Li
Micromachines 2023, 14(2), 484; https://doi.org/10.3390/mi14020484 - 19 Feb 2023
Cited by 1 | Viewed by 1076
Abstract
In this study, a numerical model was developed to predict the wettable parameters of an axisymmetric large-volume droplet on a microstructured surface in gravity. We defined a droplet with the Bond number Bo>0.1 as a large-volume droplet. Bo was [...] Read more.
In this study, a numerical model was developed to predict the wettable parameters of an axisymmetric large-volume droplet on a microstructured surface in gravity. We defined a droplet with the Bond number Bo>0.1 as a large-volume droplet. Bo was calculated by using the equation Bo=ρlgγlv3V4π23 where ρl is the density of liquid, γlv is the liquid-vapor interfacial tension, g is the gravity acceleration and V is the droplet volume. The volume of a large-volume water droplet was larger than 2.7 μL. By using the total energy minimization and the arc differential method of the Bashforth–Adams equation, we got the profile, the apparent contact angle and the contact circle diameter of an axisymmetric large-volume droplet in gravity on a microstructured horizontal plane and the external spherical surface. The predictions of our model have a less than 3% error rate when compared to experiments. Our model is much more accurate than previous ellipsoidal models. In addition, our model calculates much more quickly than previous models because of the use of the arc differential method of the Bashforth–Adams equation. It shows promise for use in the design and fabrication of microfluidic devices. Full article
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13 pages, 9802 KiB  
Article
Development of an Assessment Model for the Effect of the Replacement of Minimal Artificial Ossicles on Hearing in the Inner Ear
by Junyi Liang, Jiakun Wang, Wenjuan Yao and Mianzhi Wang
Micromachines 2023, 14(2), 483; https://doi.org/10.3390/mi14020483 - 19 Feb 2023
Cited by 1 | Viewed by 1286
Abstract
Due to ethical issues and the nature of the ear, it is difficult to directly perform experimental measurements on living body elements of the human ear. Therefore, a numerical model has been developed to effectively assess the effect of the replacement of artificial [...] Read more.
Due to ethical issues and the nature of the ear, it is difficult to directly perform experimental measurements on living body elements of the human ear. Therefore, a numerical model has been developed to effectively assess the effect of the replacement of artificial ossicles on hearing in the inner ear. A healthy volunteer’s right ear was scanned to obtain CT data, which were digitalized through the use of a self-compiling program and coalescent Patran-Nastran software to establish a 3D numerical model of the whole ear, and a frequency response of a healthy human ear was analyzed. The vibration characteristics of the basilar membrane (BM) after total ossicular replacement prosthesis (TORP) implantation were then analyzed. The results show that although the sound conduction function of the middle ear was restored after replacement of the TORP, the sensory sound function of the inner ear was affected. In the low frequency and medium frequency range, hearing loss was 5.2~10.7%. Meanwhile, in the middle–high frequency range, the replacement of a middle ear TORP in response to high sound pressure produced a high acoustic stimulation effect in the inner ear, making the inner ear structures susceptible to fatigue and more prone to fatigue damage compared to the structures in healthy individuals. This developed model is able to assess the effects of surgical operation on the entire hearing system. Full article
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12 pages, 2017 KiB  
Article
Research on Intelligent Identification and Grading of Nonmetallic Inclusions in Steels Based on Deep Learning
by Xiaolin Zhu, Wenhai Wan, Ling Qian, Yu Cai, Xiang Chen, Pingze Zhang, Guanxi Huang, Bo Liu, Qiang Yao, Shaoyuan Li and Zhengjun Yao
Micromachines 2023, 14(2), 482; https://doi.org/10.3390/mi14020482 - 19 Feb 2023
Cited by 1 | Viewed by 1402
Abstract
Non-metallic inclusions are unavoidable defects in steel, and their type, quantity, size, and distribution have a great impact on the quality of steel. At present, non-metallic inclusions are mainly detected manually, which features high work intensity, low efficiency, proneness to misjudgment, and low [...] Read more.
Non-metallic inclusions are unavoidable defects in steel, and their type, quantity, size, and distribution have a great impact on the quality of steel. At present, non-metallic inclusions are mainly detected manually, which features high work intensity, low efficiency, proneness to misjudgment, and low consistency of results. In this paper, based on deep neural network algorithm, a small number of manually labeled, low-resolution metallographic images collected by optical microscopes are used as the dataset for intelligent boundary extraction, classification, and rating of non-metallic inclusions. The training datasets are cropped into those containing only a single non-metallic inclusion to reduce the interference of background information and improve the accuracy. To deal with the unbalanced distribution of each category of inclusions, the reweighting cross entropy loss and focal loss are respectively used as the category prediction loss and boundary prediction loss of the DeepLabv3+ semantic segmentation model. Finally, the length and width of the minimum enclosing rectangle of the segmented inclusions are measured to calculate the grade of inclusions. The resulting accuracy is 90.34% in segmentation and 90.35% in classification. As is verified, the model-based rating results are consistent with those of manual labeling. For a single sample, the detection time is reduced from 30 min to 15 s, significantly improving the detection efficiency. Full article
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24 pages, 6492 KiB  
Article
A Model-Driven Platform for Dynamic Partially Reconfigurable Architectures: A Case Study of a Watermarking System
by Roukaya Dalbouchi, Chiraz Trabelsi, Majdi Elhajji and Abdelkrim Zitouni
Micromachines 2023, 14(2), 481; https://doi.org/10.3390/mi14020481 - 19 Feb 2023
Cited by 1 | Viewed by 1401
Abstract
The reconfigurable feature of FPGAs (Field-Programmable Gate Arrays) has made them a very attractive solution for implementing adaptive systems-on-chip. However, this implies additional design tasks to handle system reconfiguration and control, which increases design complexity. To address this issue, this paper proposes a [...] Read more.
The reconfigurable feature of FPGAs (Field-Programmable Gate Arrays) has made them a very attractive solution for implementing adaptive systems-on-chip. However, this implies additional design tasks to handle system reconfiguration and control, which increases design complexity. To address this issue, this paper proposes a model-driven design flow that guides the designer through the description of the different elements of a reconfigurable system. It is based on high-level modeling using an extended version of the MARTE (Modeling and Analysis of Real-Time and Embedded systems) UML (Unified Modeling Language) profile. Both centralized and decentralized reconfiguration decision-making solutions are possible with the proposed flow, allowing it to adapt to various reconfigurable systems constraints. It also integrates the IP-XACT standard (standard for the description of electronic Intellectual Properties), allowing the designer to easily target different technologies and commercial FPGAs by reusing both high-level models and actual IP-XACT hardware components. At the end of the flow, the implementation code is generated automatically from the high-level models. The proposed design flow was validated through a reconfigurable video watermarking application as a case study. Experimental results showed that the generated system allowed a good trade-off between resource usage, power consumption, execution time, and image quality compared to static implementations. This hardware efficiency was achieved in a very short time thanks to the design acceleration and automation offered by model-driven engineering. Full article
(This article belongs to the Special Issue Network on Chip (NoC) and Reconfigurable Systems)
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14 pages, 5507 KiB  
Article
Design and Testing of a Novel Nested, Compliant, Constant-Force Mechanism with Millimeter-Scale Strokes
by Xuejiao Qin, Shuaishuai Lu, Pengbo Liu and Peng Yan
Micromachines 2023, 14(2), 480; https://doi.org/10.3390/mi14020480 - 18 Feb 2023
Cited by 2 | Viewed by 1540
Abstract
This paper presents a novel nested, compliant, constant-force mechanism (CFM) that generates millimeter-scale manipulation stroke. The nested structure is utilized to improve the overall compactness of the CFM. A combination strategy of positive and negative stiffness is induced to generate constant force with [...] Read more.
This paper presents a novel nested, compliant, constant-force mechanism (CFM) that generates millimeter-scale manipulation stroke. The nested structure is utilized to improve the overall compactness of the CFM. A combination strategy of positive and negative stiffness is induced to generate constant force with a millimeter-level range. In particular, bi-stable beams are used as the negative stiffness part, and V-shaped beams are selected as the positive stiffness part, and they are constructed into the nested structures. With this, a design concept of the CFM is first proposed. From this, an analytical model of the CFM was developed based on the pseudo-rigid body method (PRBM) and chain beam constraint model (CBCM), which was verified by conducting a simulation study with nonlinear finite-element analysis (FEA). Meanwhile, a parametric study was conducted to investigate the influence of the dominant design variable on the CFM performance. To demonstrate the performance of the CFM, a prototype was fabricated by wire cutting. The experimental results revealed that the proposed CFM owns a good constant-force property. This configuration of CFM provides new ideas for the design of millimeter-scale, constant-force, micro/nano, and hard-surface manipulation systems. Full article
(This article belongs to the Special Issue Micro/Nano Fabrication in Microdevices and Integrated Systems)
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10 pages, 3410 KiB  
Article
Dual-Passband SAW Filter Based on a 32°YX-LN/SiO2/SiC Multilayered Substrate
by Huiping Xu, Sulei Fu, Rongxuan Su, Peisen Liu, Rui Wang, Fei Zeng, Cheng Song, Weibiao Wang and Feng Pan
Micromachines 2023, 14(2), 479; https://doi.org/10.3390/mi14020479 - 18 Feb 2023
Cited by 3 | Viewed by 1945
Abstract
To meet the demands of highly integrated and miniaturized radio frequency front-end (RFFE) modules, multi-passband filters which support multi-channel compounding come to the foreground. In this work, we proposed a new design of a dual-passband surface acoustic wave (SAW) filter based on a [...] Read more.
To meet the demands of highly integrated and miniaturized radio frequency front-end (RFFE) modules, multi-passband filters which support multi-channel compounding come to the foreground. In this work, we proposed a new design of a dual-passband surface acoustic wave (SAW) filter based on a 32°YX-LiNbO3 (LN)/SiO2/SiC multilayered structure. The filter is of a standalone ladder topology and comprises dual-mode resonators, in which the shear horizontal (SH) mode and high-order SH mode are simultaneously excited through electrode thickness modulation. The impact of electrode thickness on the performance of the dual-mode resonator was systematically investigated by the finite element method (FEM), and resonators were prepared and verified the simulation results. The electromechanical coupling coefficients (K2) of the SH modes are 15.1% and 17.0%, while the maximum Bode-Q (Qmax) values are 150 and 247, respectively, for the fabricated resonators with wavelengths of 1 μm and 1.1 μm. In terms of the high-order SH modes in these resonators, the K2 values are 9.8% and 8.4%, and Qmax values are 190 and 262, respectively. The fabricated dual-band filter shows the center frequencies (fc) of 3065 MHz and 4808 MHz as two bands, with 3-dB fractional bandwidths (FBW) of 5.1% and 5.9%, respectively. Such a dual-band SAW filter based on a conventional ladder topology is meaningful in terms of its compact layout and diminished area occupancy. This work provides a promising avenue to constitute a high-performance dual-passband SAW filter for sub-6 GHz RF application. Full article
(This article belongs to the Special Issue Advanced Electrostatic Sensors and Actuators)
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21 pages, 7962 KiB  
Review
Recent Advances in Micro-LEDs Having Yellow–Green to Red Emission Wavelengths for Visible Light Communications
by Konthoujam James Singh, Wei-Ta Huang, Fu-He Hsiao, Wen-Chien Miao, Tzu-Yi Lee, Yi-Hua Pai and Hao-Chung Kuo
Micromachines 2023, 14(2), 478; https://doi.org/10.3390/mi14020478 - 18 Feb 2023
Cited by 6 | Viewed by 2221
Abstract
Visible light communication (VLC), which will primarily support high-speed internet connectivity in the contemporary world, has progressively come to be recognized as a significant alternative and reinforcement in the wireless communication area. VLC has become more popular recently because of its many advantages [...] Read more.
Visible light communication (VLC), which will primarily support high-speed internet connectivity in the contemporary world, has progressively come to be recognized as a significant alternative and reinforcement in the wireless communication area. VLC has become more popular recently because of its many advantages over conventional radio frequencies, including a higher transmission rate, high bandwidth, low power consumption, fewer health risks, and reduced interference. Due to its high-bandwidth characteristics and potential to be used for both illumination and communications, micro-light-emitting diodes (micro-LEDs) have drawn a lot of attention for their use in VLC applications. In this review, a detailed overview of micro-LEDs that have long emission wavelengths for VLC is presented, along with their related challenges and future prospects. The VLC performance of micro-LEDs is influenced by a number of factors, including the quantum-confined Stark effect (QCSE), size-dependent effect, and droop effect, which are discussed in the following sections. When these elements are combined, it has a major impact on the performance of micro-LEDs in terms of their modulation bandwidth, wavelength shift, full-width at half maximum (FWHM), light output power, and efficiency. The possible challenges faced in the use of micro-LEDs were analyzed through a simulation conducted using Crosslight Apsys software and the results were compared with the previous reported results. We also provide a brief overview of the phenomena, underlying theories, and potential possible solutions to these issues. Furthermore, we provide a brief discussion regarding micro-LEDs that have emission wavelengths ranging from yellow–green to red colors. We highlight the notable bandwidth enhancement for this paradigm and anticipate some exciting new research directions. Overall, this review paper provides a brief overview of the performance of VLC-based systems based on micro-LEDs and some of their possible applications. Full article
(This article belongs to the Special Issue Micro-Light Emitting Diode: From Chips to Applications)
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42 pages, 8323 KiB  
Article
Investigation and Research of High-Performance RF MEMS Switches for Use in the 5G RF Front-End Modules
by Alexey Tkachenko, Igor Lysenko and Andrey Kovalev
Micromachines 2023, 14(2), 477; https://doi.org/10.3390/mi14020477 - 18 Feb 2023
Cited by 6 | Viewed by 1800
Abstract
In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, [...] Read more.
In this article, based on the developed methodology, the stages of designing two designs of high-performance radio-frequency single-pole single-throw microelectromechanical switches are investigated. These radio-frequency microelectromechanical switches are designed to operate at a central resonant frequency of 3.6 GHz and 3.4 GHz, respectively, as well as to work both in mobile communication devices and in the design of the architecture of 5G mobile networks, in particular in arrays of integrated antennas and radio-frequency interface modules. The manufacture and study of two designed structures are researched. For the first manufactured experimental sample in the open state the insertion loss is no more than −0.69 dB and the reflection loss is −28.35 dB, and in the closed state the isolation value is at least −54.77 dB at a central resonant frequency of 3.6 GHz. For the second in the open state the value of the insertion loss is no more than −0.67 dB and the reflection loss is −20.7 dB, and in the closed state the isolation value is not less than −52.13 dB at the central resonant frequency of 3.4 GHz. Both manufactured experimental samples are characterized by high linearity, as well as a small value of contact resistance in the closed state. Full article
(This article belongs to the Special Issue Design, Fabrication, Testing of MEMS/NEMS)
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12 pages, 4263 KiB  
Article
Fabrication and Assembly Techniques for Sub-mm Battery-Free Epicortical Implants
by Adam Khalifa, Mehdi Nasrollahpour, Ali Nezaratizadeh, Xiao Sha, Milutin Stanaćević, Nian X. Sun and Sydney S. Cash
Micromachines 2023, 14(2), 476; https://doi.org/10.3390/mi14020476 - 18 Feb 2023
Cited by 3 | Viewed by 1835
Abstract
Over the past three decades, we have seen significant advances in the field of wireless implantable medical devices (IMDs) that can interact with the nervous system. To further improve the stability, safety, and distribution of these interfaces, a new class of implantable devices [...] Read more.
Over the past three decades, we have seen significant advances in the field of wireless implantable medical devices (IMDs) that can interact with the nervous system. To further improve the stability, safety, and distribution of these interfaces, a new class of implantable devices is being developed: single-channel, sub-mm scale, and wireless microelectronic devices. In this research, we describe a new and simple technique for fabricating and assembling a sub-mm, wirelessly powered stimulating implant. The implant consists of an ASIC measuring 900 × 450 × 80 µm3, two PEDOT-coated microelectrodes, an SMD inductor, and a SU-8 coating. The microelectrodes and SMD are directly mounted onto the ASIC. The ultra-small device is powered using electromagnetic (EM) waves in the near-field using a two-coil inductive link and demonstrates a maximum achievable power transfer efficiency (PTE) of 0.17% in the air with a coil separation of 0.5 cm. In vivo experiments conducted on an anesthetized rat verified the efficiency of stimulation. Full article
(This article belongs to the Special Issue Wireless Power Transfer Systems for Biomedical Devices)
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9 pages, 2407 KiB  
Article
Conduction Conditions for Self-Healing of Metal Interconnect Using Copper Microparticles Dispersed with Silicone Oil
by Naoki Suetsugu and Eiji Iwase
Micromachines 2023, 14(2), 475; https://doi.org/10.3390/mi14020475 - 18 Feb 2023
Viewed by 1158
Abstract
This study clarifies the conditions for the bridging and conduction of a gap on a metal interconnect using copper microparticles dispersed with silicon oil. An AC voltage applied to a metal interconnect with a gap covered by a dispersion of metal microparticles traps [...] Read more.
This study clarifies the conditions for the bridging and conduction of a gap on a metal interconnect using copper microparticles dispersed with silicon oil. An AC voltage applied to a metal interconnect with a gap covered by a dispersion of metal microparticles traps the metal microparticles in the gap owing to the influence of a dielectrophoretic force on the interconnect, thus forming a metal microparticle chain. The current was tuned independently of the applied voltage by changing the external resistance. An AC voltage of 32 kHz was applied to a 10 µm wide gap on a metal interconnect covered with 3 µm diameter copper microparticles dispersed with silicone oil. Consequently, the copper microparticle chains physically bridged the interconnect and exhibited electrical conductivity at an applied voltage of 14 Vrms or higher and a post-bridging current of 350 mArms or lower. It was shown that the copper microparticle chains did not exhibit electrical conductivity at low applied voltages, even if the microparticle chains bridged the gap. A voltage higher than a certain value was required to achieve electrical conductivity, whereas an excessive voltage caused bubble formation and destroyed the bridges. These phenomena were explained based on the applied voltage and reference value of the current after bridging. Full article
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19 pages, 6722 KiB  
Article
Transition Routes of Electrokinetic Flow in a Divergent Microchannel with Bending Walls
by Yanxia Shi, Ming Zeng, Haoxin Bai, Shuangshuang Meng, Chen Zhang, Xiaoqiang Feng, Ce Zhang, Kaige Wang and Wei Zhao
Micromachines 2023, 14(2), 474; https://doi.org/10.3390/mi14020474 - 18 Feb 2023
Cited by 1 | Viewed by 1203
Abstract
Electrokinetic flow can be generated as a highly coupled phenomenon among velocity fields, electric conductivity fields, and electric fields. It can exhibit different responses to AC electric fields in different frequency regimes, according to different instability/receptivity mechanisms. In this investigation, by both flow [...] Read more.
Electrokinetic flow can be generated as a highly coupled phenomenon among velocity fields, electric conductivity fields, and electric fields. It can exhibit different responses to AC electric fields in different frequency regimes, according to different instability/receptivity mechanisms. In this investigation, by both flow visualization and single-point laser-induced fluorescence (LIF) method, the response of AC electrokinetic flow and the transition routes towards chaos and turbulence have been experimentally investigated. It is found, when the AC frequency ff>30 Hz, the interface responds at both the neutral frequency of the basic flow and the AC frequency. However, when ff30 Hz, the interface responds only at the neutral frequency of the basic flow. Both periodic doubling and subcritical bifurcations have been observed in the transition of AC electrokinetic flow. We hope the current investigation can promote our current understanding of the ultrafast transition process of electrokinetic flow from laminar state to turbulence. Full article
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9 pages, 3495 KiB  
Article
Near-Full Current Dynamic Range THz Quantum Cascade Laser Frequency Comb
by Yu Ma, Weijiang Li, Yuanyuan Li, Junqi Liu, Ning Zhuo, Ke Yang, Jinchuan Zhang, Shenqiang Zhai, Shuman Liu, Lijun Wang and Fengqi Liu
Micromachines 2023, 14(2), 473; https://doi.org/10.3390/mi14020473 - 18 Feb 2023
Viewed by 1090
Abstract
The present study proposes a terahertz quantum cascade laser frequency comb (THz QCL FC) with a semi-insulated surface plasma waveguide characterized by a low threshold current density, high power and a wide current dynamic range. The gain dispersion value and the nonlinear susceptibility [...] Read more.
The present study proposes a terahertz quantum cascade laser frequency comb (THz QCL FC) with a semi-insulated surface plasma waveguide characterized by a low threshold current density, high power and a wide current dynamic range. The gain dispersion value and the nonlinear susceptibility were optimized based on the combination of a hybrid bound-to-continuum active region with a semi-insulated surface plasmon waveguide. Without any extra dispersion compensator, stable frequency comb operation within a current dynamic range of more than 97% of the total was revealed by the intermode beat note map. Additionally, a total comb spectral emission of about 300 GHz centered around 4.6 THz was achieved for a 3 mm long and 150 µm wide device. At 10 K, a maximum output power of 22 mW was obtained with an ultra-low threshold current density of 64.4 A·cm−2. Full article
(This article belongs to the Special Issue III–V Compound Semiconductors and Devices)
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21 pages, 2093 KiB  
Review
Strategies for the Voltammetric Detection of Loop-Mediated Isothermal Amplification
by Jesse M. Marangoni, Kenneth K. S. Ng and Arezoo Emadi
Micromachines 2023, 14(2), 472; https://doi.org/10.3390/mi14020472 - 18 Feb 2023
Cited by 1 | Viewed by 1910
Abstract
Loop-mediated isothermal amplification (LAMP) is rapidly developing into an important tool for the point-of-use detection of pathogens for both clinical and environmental samples, largely due to its sensitivity, rapidity, and adaptability to portable devices. Many methods are used to monitor LAMP, but not [...] Read more.
Loop-mediated isothermal amplification (LAMP) is rapidly developing into an important tool for the point-of-use detection of pathogens for both clinical and environmental samples, largely due to its sensitivity, rapidity, and adaptability to portable devices. Many methods are used to monitor LAMP, but not all are amenable to point-of-use applications. Common methods such as fluorescence often require bulky equipment, whereas colorimetric and turbidimetric methods can lack sensitivity. Electrochemical biosensors are becoming increasingly important for these applications due to their potential for low cost, high sensitivity, and capacity for miniaturization into integrated devices. This review provides an overview of the use of voltammetric sensors for monitoring LAMP, with a specific focus on how electroactive species are used to interface between the biochemical products of the LAMP reaction and the voltammetric sensor. Various strategies for the voltammetric detection of DNA amplicons as well as pyrophosphate and protons released during LAMP are presented, ranging from direct DNA binding by electroactive species to the creative use of pyrophosphate-detecting aptamers and pH-sensitive oligonucleotide structures. Hurdles for adapting these devices to point-of-use applications are also discussed. Full article
(This article belongs to the Special Issue Electrochemical Sensors in Biological Applications, Volume II)
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14 pages, 4650 KiB  
Article
Structural Colors on Al Surface via Capped Cu-Si3N4 Bilayer Structure
by M. A. Rahman, Dongkyu Kim, Deepshikha Arora, Joo-Youl Huh and Ji Young Byun
Micromachines 2023, 14(2), 471; https://doi.org/10.3390/mi14020471 - 18 Feb 2023
Cited by 2 | Viewed by 1361
Abstract
Tunable structural colors have a multitude of applications in the beautification of mobile devices, in the decoration of artwork, and in the creation of color filters. In this paper, we describe a Metal-Insulator-Metal (MIM) design that can be used to systematically tune structural [...] Read more.
Tunable structural colors have a multitude of applications in the beautification of mobile devices, in the decoration of artwork, and in the creation of color filters. In this paper, we describe a Metal-Insulator-Metal (MIM) design that can be used to systematically tune structural colors by altering the thickness of the top metal and intermediate insulator. Cu and Si3N4 were selected as the top metal and intermediate insulator layers, respectively, and various reflection colors were printed on Al. To protect the Cu surface from scratchiness and oxidation, a number of capping layers, including SiO2, LPSQ, PMMA, and the commercially available clear coat ProtectaClear, were applied. In addition to their ability to protect Cu from a humid environment without deteriorating color quality, ProtectaClear and LPSQ coatings have minimal angle dependency. Furthermore, a bilayer of PMMA/SiO2 can protect the Cu surface from the effects of humidity. In addition, the PMMA/SiO2 and ProtectaClear/SiO2 bilayers can also protect against corrosion on the Cu surface. The colors can be tuned by controlling the thickness of either the metal layer or intermediate insulator layer, and vivid structural colors including brown, dark orange, blue, violet, magenta, cyan, green-yellow, and yellow colors can be printed. The measured dielectric functions of Cu thin films do not provide any evidence of the plasmonic effect, and therefore, it is expected that the obtained colors are attributed to thin-film interference. Full article
(This article belongs to the Special Issue Photon-Driven Technologies: Exploring the Latest Advancements)
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24 pages, 10568 KiB  
Review
MEMS Enabled Miniature Two-Photon Microscopy for Biomedical Imaging
by Xiaomin Yu, Liang Zhou, Tingxiang Qi, Hui Zhao and Huikai Xie
Micromachines 2023, 14(2), 470; https://doi.org/10.3390/mi14020470 - 17 Feb 2023
Cited by 6 | Viewed by 2897
Abstract
Over the last decade, two-photon microscopy (TPM) has been the technique of choice for in vivo noninvasive optical brain imaging for neuroscientific study or intra-vital microendoscopic imaging for clinical diagnosis or surgical guidance because of its intrinsic capability of optical sectioning for imaging [...] Read more.
Over the last decade, two-photon microscopy (TPM) has been the technique of choice for in vivo noninvasive optical brain imaging for neuroscientific study or intra-vital microendoscopic imaging for clinical diagnosis or surgical guidance because of its intrinsic capability of optical sectioning for imaging deeply below the tissue surface with sub-cellular resolution. However, most of these research activities and clinical applications are constrained by the bulky size of traditional TMP systems. An attractive solution is to develop miniaturized TPMs, but this is challenged by the difficulty of the integration of dynamically scanning optical and mechanical components into a small space. Fortunately, microelectromechanical systems (MEMS) technology, together with other emerging micro-optics techniques, has offered promising opportunities in enabling miniaturized TPMs. In this paper, the latest advancements in both lateral scan and axial scan techniques and the progress of miniaturized TPM imaging will be reviewed in detail. Miniature TPM probes with lateral 2D scanning mechanisms, including electrostatic, electromagnetic, and electrothermal actuation, are reviewed. Miniature TPM probes with axial scanning mechanisms, such as MEMS microlenses, remote-focus, liquid lenses, and deformable MEMS mirrors, are also reviewed. Full article
(This article belongs to the Special Issue Optical MEMS, Volume III)
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14 pages, 1391 KiB  
Article
A Reliability System Evaluation Model of NoC Communication with Crosstalk Analysis from Backend to Frontend
by Xiaodong Weng, Xiaoling Lin, Yi Liu, Changqing Xu, Linjun Zhan, Shunyao Wang, Dongdong Chen and Yintang Yang
Micromachines 2023, 14(2), 469; https://doi.org/10.3390/mi14020469 - 17 Feb 2023
Cited by 1 | Viewed by 1428
Abstract
Network on chip (NoC) is the main solution to the communication bandwidth of a multi-processor system on chip (MPSoC). NoC also brings more route requirements and is highly prone to errors caused by crosstalk. Crosstalk has become a major design problem in deep-submicron [...] Read more.
Network on chip (NoC) is the main solution to the communication bandwidth of a multi-processor system on chip (MPSoC). NoC also brings more route requirements and is highly prone to errors caused by crosstalk. Crosstalk has become a major design problem in deep-submicron NoC communication design. Hence, a crosstalk error model and corresponding reliable system with error correction code (ECC) are required to make NoC communication reliable. In this paper, a reliability system evaluation model (RSE) of NoC communication with analysis from backend to frontend has been proposed. In the backend, a crosstalk error rate model (CER) is established with a three-wire RLC coupling model and timing constraints. The CER is used to establish functional relations between interconnect spacing, length and signal frequency, and test system reliability. In the frontend, a reliability system performance model (RSP) is established with a CER, reliability method cost and bandwidth. The RSE summarizes the frontend and backend model. In order to verify the RSE model, we propose a reliability system with a hybrid automatic repeat request technique (RSHARQ). Simulation demonstrates that the CER model is close to real circuit design. Through the CER and RSP model, the performance of RSHARQ could be simulated. Full article
(This article belongs to the Special Issue High-Reliability Semiconductor Devices and Integrated Circuits)
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11 pages, 649 KiB  
Article
Meta-Atoms with Toroidal Topology for Strongly Resonant Responses
by Odysseas Tsilipakos, Zacharias Viskadourakis, Anna C. Tasolamprou, Dimitrios C. Zografopoulos, Maria Kafesaki, George Kenanakis and Eleftherios N. Economou
Micromachines 2023, 14(2), 468; https://doi.org/10.3390/mi14020468 - 17 Feb 2023
Cited by 1 | Viewed by 1524
Abstract
A conductive meta-atom of toroidal topology is studied both theoretically and experimentally, demonstrating a sharp and highly controllable resonant response. Simulations are performed both for a free-space periodic metasurface and a pair of meta-atoms inserted within a rectangular metallic waveguide. A quasi-dark state [...] Read more.
A conductive meta-atom of toroidal topology is studied both theoretically and experimentally, demonstrating a sharp and highly controllable resonant response. Simulations are performed both for a free-space periodic metasurface and a pair of meta-atoms inserted within a rectangular metallic waveguide. A quasi-dark state with controllable radiative coupling is supported, allowing to tune the linewidth (quality factor) and lineshape of the supported resonance via the appropriate geometric parameters. By conducting a rigorous multipole analysis, we find that despite the strong toroidal dipole moment, it is the residual electric dipole moment that dictates the electromagnetic response. Subsequently, the structure is fabricated with 3D printing and coated with silver paste. Importantly, the structure is planar, consists of a single metallization layer and does not require a substrate when neighboring meta-atoms are touching, resulting in a practical, thin and potentially low-loss system. Measurements are performed in the 5 GHz regime with a vector network analyzer and a good agreement with simulations is demonstrated. Full article
(This article belongs to the Special Issue Micro/Nanophotonic Devices in Europe)
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13 pages, 3138 KiB  
Article
Power Enhancement of 265 nm DUV-LED Flip-Chip by HVPE-AlN High-Temperature Annealing
by Wenkai Yue, Ruixuan Liu, Peixian Li, Xiaowei Zhou, Yang Liu, Bo Yang, Yingxiao Liu and Xiaowei Wang
Micromachines 2023, 14(2), 467; https://doi.org/10.3390/mi14020467 - 17 Feb 2023
Cited by 5 | Viewed by 1348
Abstract
In this paper, the X-ray diffraction full width at half the maximum (XRD FWHM) of a 3.5 µm-thick hydride vapor phase epitaxy-aluminum nitride (HVPE-AlN) (002) face after high-temperature annealing was reduced to 129 arcsec. The tensile strain in the HVPE-AlN samples gradually released [...] Read more.
In this paper, the X-ray diffraction full width at half the maximum (XRD FWHM) of a 3.5 µm-thick hydride vapor phase epitaxy-aluminum nitride (HVPE-AlN) (002) face after high-temperature annealing was reduced to 129 arcsec. The tensile strain in the HVPE-AlN samples gradually released with the increasing annealing temperature. When the annealing temperature exceeded 1700 °C, an aluminum oxynitride (AlON) region was generated at the contact interface between HVPE-AlN and sapphire, and the AlON structure was observed to conform to the characteristics of Al5O6N by high-resolution transmission electron microscopy (HRTEM). A 265 nm light-emitting diode (LED) based on an HVPE-AlN template annealed at 1700 °C achieved a light output power (LOP) of 4.48 mW at 50 mA, which was approximately 57% greater than that of the original sample. Full article
(This article belongs to the Special Issue Solid-State Quantum Materials and Device Systems)
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10 pages, 2896 KiB  
Article
Cost-Effective Droplet Generator for Portable Bio-Applications
by Lin Du, Yuxin Li, Jie Wang, Zijian Zhou, Tian Lan, Dalei Jing, Wenming Wu and Jia Zhou
Micromachines 2023, 14(2), 466; https://doi.org/10.3390/mi14020466 - 17 Feb 2023
Cited by 1 | Viewed by 1735
Abstract
The convenient division of aqueous samples into droplets is necessary for many biochemical and medical analysis applications. In this article, we propose the design of a cost-effective droplet generator for potential bio-chemical application, featuring two symmetric tubes. The new droplet generator revisits the [...] Read more.
The convenient division of aqueous samples into droplets is necessary for many biochemical and medical analysis applications. In this article, we propose the design of a cost-effective droplet generator for potential bio-chemical application, featuring two symmetric tubes. The new droplet generator revisits the relationship between capillary components and liquid flow rates. The size of generated droplets by prototype depends only on generator dimensions, without precisely needing to control external flow conditions or driving pressure, even when the relative extreme difference in flow rate for generating nL level droplets is over 57.79%, and the relative standard deviation (RSD) of the volume of droplets is barely about 9.80%. A dropper working as a pressure resource is used to verify the rapidity and robustness of this principle of droplet generation, which shows great potential for a wide range of droplet-based applications. Full article
(This article belongs to the Special Issue μ-TAS: A Themed Issue in Honor of Professor Andreas Manz)
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10 pages, 7083 KiB  
Article
A Broadband Vortex Beam Generator Based on Single-Layer Hybrid Phase-Turning Metasurface
by Cheng Fu, Jianing Zhao, Fang Li and Hao Li
Micromachines 2023, 14(2), 465; https://doi.org/10.3390/mi14020465 - 17 Feb 2023
Cited by 3 | Viewed by 1344
Abstract
Vortex beams carrying orbital angular momentum (OAM) have become a research frontier due to the prospect of improving spectral efficiency and transmission capacity in communication systems. In this work, a hybrid phase-turning meta-atom that combines resonance and geometric (Pancharatnam-Berry) phase modulation is used [...] Read more.
Vortex beams carrying orbital angular momentum (OAM) have become a research frontier due to the prospect of improving spectral efficiency and transmission capacity in communication systems. In this work, a hybrid phase-turning meta-atom that combines resonance and geometric (Pancharatnam-Berry) phase modulation is used to form a single-layer metasurface. A linearly polarized broadband vortex beam of mode l = −1 is obtained by the metasurface. An experimental prototype of the vortex beam generator has been fabricated and measured. The simulated and measured results demonstrate that the whole vortex beam generator exhibits over 70% mode purity from 26.5 GHz to 40 GHz (the relative bandwidth is 38.57%). In addition, a wide 3 dB gain bandwidth and low crosstalk are also provided by the proposed generator. This indicates that the proposed generator has important application value for vortex beam communication and its related applications. Full article
(This article belongs to the Special Issue Microwave Antennas: From Fundamental Research to Applications)
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