Micromachines

17 pages, 6854 KiB

Open AccessArticle

Experimental Research on a New Mini-Channel Transcritical CO₂ Heat Pump Gas Cooler

by Jiawei Jiang, Shiqiang Liang, Xiang Xu, Buze Chen, Zhixuan Shen, Chaohong Guo, Liqi Yu and Shuo Qin

Micromachines 2023, 14(5), 1094; https://doi.org/10.3390/mi14051094 - 22 May 2023

Cited by 1 | Viewed by 1201

Abstract

This paper presents the results of an experimental study on the heat transfer and pressure drop characteristics of a novel spiral plate mini-channel gas cooler designed for use with supercritical CO₂. The CO₂ channel of the mini-channel spiral plate gas [...] Read more.

This paper presents the results of an experimental study on the heat transfer and pressure drop characteristics of a novel spiral plate mini-channel gas cooler designed for use with supercritical CO₂. The CO₂ channel of the mini-channel spiral plate gas cooler has a circular spiral cross-section with a radius of 1 mm, while the water channel has an elliptical cross-section spiral channel with a long axis of 2.5 mm and a short axis of 1.3 mm. The results show that increasing the mass flux of CO₂ can effectively enhance the overall heat transfer coefficient when the water side mass flow rate is 0.175 kg·s⁻¹ and the CO₂ side pressure is 7.9 MPa. Increasing the inlet water temperature can also improve the overall heat transfer coefficient. The overall heat transfer coefficient is higher when the gas cooler is vertically oriented compared to horizontally oriented. A Matlab program was developed to verify that the correlation based on Zhang’s method has the highest accuracy. The study found a suitable heat transfer correlation for the new spiral plate mini-channel gas cooler through experimental research, which can provide a reference for future designs. Full article

(This article belongs to the Special Issue Heat and Mass Transfer Enhancement in Microchannels)

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17 pages, 3417 KiB

Open AccessArticle

An Online Measurement and Calibration Method for a Radio Telescope Sub-Reflector Support Structure Using Fiber Bragg Grating

by Qian Xu and Hong Bao

Micromachines 2023, 14(5), 1093; https://doi.org/10.3390/mi14051093 - 22 May 2023

Viewed by 1034

Abstract

The position and altitude of a sub-reflector have an important influence on the pointing accuracy of a radio telescope. With the increase of the antenna aperture, the stiffness of the support structure for the sub-reflector decreases. This causes deformation of the support structure [...] Read more.

The position and altitude of a sub-reflector have an important influence on the pointing accuracy of a radio telescope. With the increase of the antenna aperture, the stiffness of the support structure for the sub-reflector decreases. This causes deformation of the support structure when environmental loads, such as gravity, temperature, and wind load, are applied to the sub-reflector, which will seriously influence antenna pointing accuracy. This paper proposes an online measurement and calibration method for assessing the deformation of the sub-reflector support structure based on the Fiber Bragg Grating (FBG) sensors. Firstly, a reconstruction model between the strain measurements and the deformation displacements of a sub-reflector support structure is established based on the inverse finite element method (iFEM). In addition, a temperature-compensating device with an FBG sensor is designed to eliminate the effects of temperature variations on strain measurements. Considering the lack of the trained original correction, a non-uniform rational B spline (NURBS) curve is built to extend the sample data set. Next, a self-structuring fuzzy network (SSFN) is designed for calibrating the reconstruction model, which can further improve the displacement reconstruction accuracy of the support structure. Finally, a full-day experiment was carried out using a sub-reflector support model to verify the effectiveness of the proposed method. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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15 pages, 1902 KiB

Open AccessArticle

5-Fluorouracil-Encapsulated Films Using Exopolysaccharides from a Thermophilic Bacterium Geobacillus sp. WSUCF1 for Topical Drug Delivery

by Joseph M. Laubach and Rajesh K. Sani

Micromachines 2023, 14(5), 1092; https://doi.org/10.3390/mi14051092 - 22 May 2023

Viewed by 1066

Abstract

Bacteria are capable of producing a specific type of biopolymer, termed exopolysaccharides (EPSs). EPSs from thermophile Geobacillus sp. strain WSUCF1 specifically can be assembled using cost-effective lignocellulosic biomass as the primary carbon substrate in lieu of traditional sugars. 5-fluorouracil (5-FU) is an FDA-approved, [...] Read more.

Bacteria are capable of producing a specific type of biopolymer, termed exopolysaccharides (EPSs). EPSs from thermophile Geobacillus sp. strain WSUCF1 specifically can be assembled using cost-effective lignocellulosic biomass as the primary carbon substrate in lieu of traditional sugars. 5-fluorouracil (5-FU) is an FDA-approved, versatile chemotherapeutic that has yielded high efficacy against colon, rectum, and breast cancers. The present study investigates the feasibility of a 5% 5-fluorouracil film using thermophilic exopolysaccharides as the foundation in conjunction with a simple self-forming method. The drug-loaded film formulation was seen to be highly effective against A375 human malignant melanoma at its current concentration with viability of A375 dropping to 12% after six hours of treatment. A drug release profile revealed a slight burst release before it settled into an extended and maintained release of 5-FU. These initial findings provide evidence for the versatility of thermophilic exopolysaccharides produced from lignocellulosic biomass to act as a chemotherapeutic-delivering device and expand the overall applications of extremophilic EPSs. Full article

(This article belongs to the Special Issue Biomaterials, Biodevices and Tissue Engineering)

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16 pages, 6624 KiB

Open AccessArticle

An Improved Blind Zone Channelization Structure and Rapid Implementation Method

by Ziliang Jia and Hongxia Liu

Micromachines 2023, 14(5), 1091; https://doi.org/10.3390/mi14051091 - 22 May 2023

Viewed by 912

Abstract

The paper proposes an enhanced design for broadband digital receivers that aims to improve signal capture probability, real-time performance, and the hardware development cycle. To overcome the issue of false signals in the blind zone channelization structure, this paper introduces an improved joint-decision [...] Read more.

The paper proposes an enhanced design for broadband digital receivers that aims to improve signal capture probability, real-time performance, and the hardware development cycle. To overcome the issue of false signals in the blind zone channelization structure, this paper introduces an improved joint-decision channelization structure that reduces channel ambiguity during signal reception. Xilinx’s high-level synthesis (HLS) tools are used for accelerated algorithm implementation, and techniques such as pipelining and loop parallelization are employed to reduce system latency. The entire system is implemented on FPGA. The simulation results demonstrate that the proposed solution effectively eliminates channel ambiguity, improves algorithm implementation speed, and meets the design requirements. Full article

(This article belongs to the Special Issue FPGA Applications and Future Trends)

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10 pages, 2108 KiB

Open AccessArticle

Performance Degradation in Static Random Access Memory of 10 nm Node FinFET Owing to Displacement Defects

by Minji Bang, Jonghyeon Ha, Gyeongyeop Lee, Minki Suh and Jungsik Kim

Micromachines 2023, 14(5), 1090; https://doi.org/10.3390/mi14051090 - 22 May 2023

Viewed by 1068

Abstract

We comprehensively investigate displacement-defect-induced current and static noise margin variations in six-transistor (6T) static random access memory (SRAM) based on a 10 nm node fin field-effect transistor (FinFET) using technology computer-aided design (TCAD). Various defect cluster conditions and fin structures are considered as [...] Read more.

We comprehensively investigate displacement-defect-induced current and static noise margin variations in six-transistor (6T) static random access memory (SRAM) based on a 10 nm node fin field-effect transistor (FinFET) using technology computer-aided design (TCAD). Various defect cluster conditions and fin structures are considered as variables to estimate the worst-case scenario for displacement defects. The rectangular defect clusters capture more widely distributed charges at the fin top, reducing the on- and off-current. The read static noise margin (RSNM) is the most degraded in the pull-down transistor during the read operation. The increased fin width decreases the RSNM due to the gate field. The current per cross-sectional area increases when the fin height decreases, but the energy barrier lowering by the gate field is similar. Therefore, the reduced fin width and increased fin height structure suit the 10 nm node FinFET 6T SRAMs with high radiation hardness. Full article

(This article belongs to the Special Issue Spintronic Memory and Logic Devices)

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11 pages, 4032 KiB

Open AccessArticle

Lateral Extensional Mode Piezoelectric ZnO-on-Nickel RF MEMS Resonators for Back-End-of-Line Integration

by Adnan Zaman, Abdulrahman Alsolami, Mian Wei, Ivan Rivera, Masoud Baghelani and Jing Wang

Micromachines 2023, 14(5), 1089; https://doi.org/10.3390/mi14051089 - 22 May 2023

Cited by 2 | Viewed by 1152

Abstract

High motional resistance and incompatibility with post-CMOS fabrication due to thermal budget constraints are imperative issues associated with the back-end-of-line integration of lateral extensional vibrating micromechanical resonators. This paper presents piezoelectric ZnO-on-nickel resonators as a viable means for mitigating both of the issues. [...] Read more.

High motional resistance and incompatibility with post-CMOS fabrication due to thermal budget constraints are imperative issues associated with the back-end-of-line integration of lateral extensional vibrating micromechanical resonators. This paper presents piezoelectric ZnO-on-nickel resonators as a viable means for mitigating both of the issues. Lateral extensional mode resonators equipped with thin-film piezoelectric transducers can exhibit much lower motional impedances than their capacitive counterparts due to piezo-transducers’ higher electromechanical coupling coefficients. Meanwhile, the employment of electroplated nickel as the structural material allows the process temperature to be kept lower than 300 °C, which is low enough for the post-CMOS resonator fabrication. In this work, various geometrical rectangular and square plates resonators are investigated. Moreover, parallel combination of several resonators into a mechanically coupled array was explored as a systematic approach to lower motional resistance from ~1 kΩs to 0.562 kΩs. Higher order modes were investigated for achieving higher resonance frequencies up to 1.57 GHz. Local annealing by Joule heating was also exploited for quality factor improvement after device fabrication by ~2× enhancement and breaking the record of MEMS electroplated nickel resonators in lowering insertion loss to ~10 dB. Full article

(This article belongs to the Special Issue Smart Materials for MEMS Devices)

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19 pages, 3409 KiB

Open AccessReview

Advances in MXene-Based Electrochemical (Bio)Sensors for Neurotransmitter Detection

by Meiqing Yang, Lu Wang, Haozi Lu and Qizhi Dong

Micromachines 2023, 14(5), 1088; https://doi.org/10.3390/mi14051088 - 21 May 2023

Cited by 9 | Viewed by 2386

Abstract

Neurotransmitters are chemical messengers that play an important role in the nervous system’s control of the body’s physiological state and behaviour. Abnormal levels of neurotransmitters are closely associated with some mental disorders. Therefore, accurate analysis of neurotransmitters is of great clinical importance. Electrochemical [...] Read more.

Neurotransmitters are chemical messengers that play an important role in the nervous system’s control of the body’s physiological state and behaviour. Abnormal levels of neurotransmitters are closely associated with some mental disorders. Therefore, accurate analysis of neurotransmitters is of great clinical importance. Electrochemical sensors have shown bright application prospects in the detection of neurotransmitters. In recent years, MXene has been increasingly used to prepare electrode materials for fabricating electrochemical neurotransmitter sensors due to its excellent physicochemical properties. This paper systematically introduces the advances in MXene-based electrochemical (bio)sensors for the detection of neurotransmitters (including dopamine, serotonin, epinephrine, norepinephrine, tyrosine, NO, and H₂S), with a focus on their strategies for improving the electrochemical properties of MXene-based electrode materials, and provides the current challenges and future prospects for MXene-based electrochemical neurotransmitter sensors. Full article

(This article belongs to the Section C：Chemistry)

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17 pages, 7419 KiB

Open AccessArticle

Synthesis of Nano Pigments Using Clay Minerals and Organic Dyes and Their Application as Colorants in Polymer Matrix

by Chandra Mohan, Neeraj Kumari, Philippe Jeandet, Priyanka Kumari and Arvind Negi

Micromachines 2023, 14(5), 1087; https://doi.org/10.3390/mi14051087 - 21 May 2023

Viewed by 1888

Abstract

A new generation of clay-based nano pigments has been introduced, providing the advantage of both inorganic pigments and organic dyes. These nano pigments have been synthesized through a stepwise procedure where, initially, an organic dye is adsorbed onto the surface of the adsorbent, [...] Read more.

A new generation of clay-based nano pigments has been introduced, providing the advantage of both inorganic pigments and organic dyes. These nano pigments have been synthesized through a stepwise procedure where, initially, an organic dye is adsorbed onto the surface of the adsorbent, and then dye adsorbed adsorbent is used as pigment for further applications. The objective of the current paper was to examine the interaction of non-biodegradable toxic dyes, Crystal Violet (CV) and Indigo Carmine (IC), with clay minerals (montmorillonite (Mt), vermiculite (Vt), and clay bentonite (Bent)) and their organically modified forms (OMt, OBent, and OVt) and to develop a novel methodology for the synthesis of the value-added products and clay-based nano pigments without creating second generation waste materials. In our observation, the uptake of CV was more intense onto pristine Mt, Bent, and Vt, and the uptake of IC was more onto OMt, OBent, and OVt. CV was found to be in the interlayer region of Mt and Bent, as supported by XRD data. Zeta potential values confirmed the presence of CV on their surface. In contrast, in the case of Vt and organically modified forms, the dye was found on the surface, confirmed by XRD and zeta potential values. In the case of indigo carmine, the dye was found only on the surface of pristine Mt, Bent, Vt, and organo Mt, Bent, Vt. During the interaction of CV and IC with clay and organoclays, intense violet and blue-colored solid residues were obtained (also known as clay-based nano pigments). The nano pigments were used as colorants in a poly (methyl-methacrylate) (PMMA) polymer matrix to form transparent polymer films. Full article

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16 pages, 2794 KiB

Open AccessArticle

A Novel NanoMIP–SPR Sensor for the Point-of-Care Diagnosis of Breast Cancer

by Kadir Erol, Gauri Hasabnis and Zeynep Altintas

Micromachines 2023, 14(5), 1086; https://doi.org/10.3390/mi14051086 - 21 May 2023

Cited by 2 | Viewed by 1961

Abstract

Simple, fast, selective, and reliable detection of human epidermal growth factor receptor 2 (HER2) is of utmost importance in the early diagnosis of breast cancer to prevent its high prevalence and mortality. Molecularly imprinted polymers (MIPs), also known as artificial antibodies, have recently [...] Read more.

Simple, fast, selective, and reliable detection of human epidermal growth factor receptor 2 (HER2) is of utmost importance in the early diagnosis of breast cancer to prevent its high prevalence and mortality. Molecularly imprinted polymers (MIPs), also known as artificial antibodies, have recently been used as a specific tool in cancer diagnosis and therapy. In this study, a miniaturized surface plasmon resonance (SPR)-based sensor was developed using epitope-mediated HER2-nanoMIPs. The nanoMIP receptors were characterized using dynamic light scattering (DLS), zeta potential, Fourier-transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and fluorescent microscopy. The average size of the nanoMIPs was determined to be 67.5 ± 12.5 nm. The proposed novel SPR sensor provided superior selectivity to HER2 with a detection limit (LOD) of 11.6 pg mL⁻¹ in human serum. The high specificity of the sensor was confirmed by cross-reactivity studies using P53, human serum albumin (HSA), transferrin, and glucose. The sensor preparation steps were successfully characterized by employing cyclic and square wave voltammetry. The nanoMIP–SPR sensor demonstrates great potential for use in the early diagnosis of breast cancer as a robust tool with high sensitivity, selectivity, and specificity. Full article

(This article belongs to the Special Issue State-of-the-Art Optical Biosensors)

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14 pages, 3640 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

A Wireless, High-Quality, Soft and Portable Wrist-Worn System for sEMG Signal Detection

by Zekai Liang, Xuanqi Wang, Jun Guo, Yuanming Ye, Haoyang Zhang, Liang Xie, Kai Tao, Wen Zeng, Erwei Yin and Bowen Ji

Micromachines 2023, 14(5), 1085; https://doi.org/10.3390/mi14051085 - 21 May 2023

Cited by 1 | Viewed by 1694

Abstract

The study of wearable systems based on surface electromyography (sEMG) signals has attracted widespread attention and plays an important role in human–computer interaction, physiological state monitoring, and other fields. Traditional sEMG signal acquisition systems are primarily targeted at body parts that are not [...] Read more.

The study of wearable systems based on surface electromyography (sEMG) signals has attracted widespread attention and plays an important role in human–computer interaction, physiological state monitoring, and other fields. Traditional sEMG signal acquisition systems are primarily targeted at body parts that are not in line with daily wearing habits, such as the arms, legs, and face. In addition, some systems rely on wired connections, which impacts their flexibility and user-friendliness. This paper presents a novel wrist-worn system with four sEMG acquisition channels and a high common-mode rejection ratio (CMRR) greater than 120 dB. The circuit has an overall gain of 2492 V/V and a bandwidth of 15~500 Hz. It is fabricated using flexible circuit technologies and is encapsulated in a soft skin-friendly silicone gel. The system acquires sEMG signals at a sampling rate of over 2000 Hz with a 16-bit resolution and transmits data to a smart device via low-power Bluetooth. Muscle fatigue detection and four-class gesture recognition experiments (accuracy greater than 95%) were conducted to validate its practicality. The system has potential applications in natural and intuitive human–computer interaction and physiological state monitoring. Full article

(This article belongs to the Special Issue Wearable and Implantable Bio-MEMS Devices and Applications)

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12 pages, 5722 KiB

Open AccessArticle

An Investigation of SILC Degradation under Constant Voltage Stress in PDSOI Devices

by Yong Lu and Hongxia Liu

Micromachines 2023, 14(5), 1084; https://doi.org/10.3390/mi14051084 - 21 May 2023

Viewed by 981

Abstract

The stress-induced leakage current (SILC) degradation of partially depleted silicon in insulator (PDSOI) devices under constant voltage stress (CVS) was studied. Firstly, the behaviors of threshold voltage degradation and SILC degradation of H-gate PDSOI devices under constant voltage stress were studied. It was [...] Read more.

The stress-induced leakage current (SILC) degradation of partially depleted silicon in insulator (PDSOI) devices under constant voltage stress (CVS) was studied. Firstly, the behaviors of threshold voltage degradation and SILC degradation of H-gate PDSOI devices under constant voltage stress were studied. It was found that both the threshold voltage degradation and SILC degradation of the device are power functions of the stress time, and the linear behavior between SILC degradation and threshold voltage degradation is good. Secondly, the soft breakdown characteristics of the PDSOI devices were studied under CVS. Thirdly, the effects of different gate stresses and different channel lengths on the threshold voltage degradation and SILC degradation of the device were studied. The results showed SILC degradation of the device under positive CVS and SILC degradation of the device under negative CVS. The shorter the channel length of the device was, the greater the SILC degradation of the device was. Finally, the influence of the floating effect on the SILC degradation of the PDSOI devices was studied, and the experimental results showed that the degree of SILC degradation of the floating device was greater than that of the H-type grid body contact PDSOI device. This showed that the floating body effect can exacerbate the SILC degradation of PDSOI devices. Full article

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8 pages, 1358 KiB

Open AccessCommunication

Direct Synthesis of Mn₃[Fe(CN)₆]₂·nH₂O Nanosheets as Novel 2D Analog of Prussian Blue and Material for High-Performance Metal-Ion Batteries

by Artem A. Lobinsky, Maria V. Kaneva, Maxim I. Tenevich and Vadim I. Popkov

Micromachines 2023, 14(5), 1083; https://doi.org/10.3390/mi14051083 - 21 May 2023

Cited by 2 | Viewed by 1304

Abstract

Rechargeable metal-ion batteries (RMIBs) are prospective highly effective and low-cost devices for energy storage. Prussian blue analogues (PBAs) have become a subject of significant interest for commercial applications owing to their exceptional specific capacity and broad operational potential window as cathode materials for [...] Read more.

Rechargeable metal-ion batteries (RMIBs) are prospective highly effective and low-cost devices for energy storage. Prussian blue analogues (PBAs) have become a subject of significant interest for commercial applications owing to their exceptional specific capacity and broad operational potential window as cathode materials for rechargeable metal-ion batteries. However, the limiting factors for its widespread use are its poor electrical conductivity and stability. The present study describes the direct and simple synthesis of 2D nanosheets of MnFCN (Mn₃[Fe(CN)₆]₂·nH₂O) on nickel foam (NF) via a successive ionic layer deposition (SILD) method, which provided more ion diffusion and electrochemical conductivity. MnFCN/NF exhibited exceptional cathode performance for RMIBs, delivering a high specific capacity of 1032 F/g at 1 A/g in an aqueous 1M NaOH electrolyte. Additionally, the specific capacitance reached the remarkable levels of 327.5 F/g at 1 A/g and 230 F/g at 0.1 A/g in 1M Na₂SO₄ and 1M ZnSO₄ aqueous solutions, respectively. Full article

(This article belongs to the Special Issue Thin Film Deposition: From Fundamental Research to Applications)

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20 pages, 23394 KiB

Open AccessArticle

A Nonlinear Impact-Driven Triboelectric Vibration Energy Harvester for Frequency Up-Conversion

by Hadeel Abumarar and Alwathiqbellah Ibrahim

Micromachines 2023, 14(5), 1082; https://doi.org/10.3390/mi14051082 - 20 May 2023

Cited by 2 | Viewed by 1007

Abstract

Energy harvesting effectively powers micro-sensors and wireless applications. However, higher frequency oscillations do not overlap with ambient vibrations, and low power can be harvested. This paper utilizes vibro-impact triboelectric energy harvesting for frequency up-conversion. Two magnetically coupled cantilever beams with low and high [...] Read more.

Energy harvesting effectively powers micro-sensors and wireless applications. However, higher frequency oscillations do not overlap with ambient vibrations, and low power can be harvested. This paper utilizes vibro-impact triboelectric energy harvesting for frequency up-conversion. Two magnetically coupled cantilever beams with low and high natural frequencies are used. The two beams have identical tip magnets at the same polarity. A triboelectric energy harvester is integrated with the high-frequency beam to generate an electrical signal via contact-separation impact motion between the triboelectric layers. An electrical signal is generated at the low-frequency beam range achieving frequency up-converter. The two degrees of freedom (2DOF) lumped-parameter model system is used to investigate the system’s dynamic behavior and the corresponding voltage signal. The static analysis of the system revealed a threshold distance of 15 mm that divides the system into monostable and bistable regimes. In the monostable and bistable regimes, softening and hardening behaviors were observed at low frequencies. Additionally, the threshold voltage generated was increased by 1117% in comparison with the monostable regime. The simulation findings were experimentally validated. The study demonstrates the potential of using triboelectric energy harvesting in frequency up-converting applications. Full article

(This article belongs to the Special Issue Piezoelectric MEMS/NEMS—Materials, Devices, and Applications, Second Edition)

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13 pages, 3965 KiB

Open AccessArticle

Influence of Aluminum and Copper on Mechanical Properties of Biocompatible Ti-Mo Alloys: A Simulation-Based Investigation

by Omid Ashkani, Mohammad Reza Tavighi, Mojtaba Karamimoghadam, Mahmoud Moradi, Mahdi Bodaghi and Mohammad Rezayat

Micromachines 2023, 14(5), 1081; https://doi.org/10.3390/mi14051081 - 20 May 2023

Cited by 10 | Viewed by 2016

Abstract

The use of titanium and titanium-based alloys in the human body due to their resistance to corrosion, implant ology and dentistry has led to significant progress in promoting new technologies. Regarding their excellent mechanical, physical and biological performance, new titanium alloys with non-toxic [...] Read more.

The use of titanium and titanium-based alloys in the human body due to their resistance to corrosion, implant ology and dentistry has led to significant progress in promoting new technologies. Regarding their excellent mechanical, physical and biological performance, new titanium alloys with non-toxic elements and long-term performance in the human body are described today. The main compositions of Ti-based alloys and properties comparable to existing classical alloys (C.P. TI, Ti-6Al-4V, Co-Cr-Mo, etc.) are used for medical applications. The addition of non-toxic elements such as Mo, Cu, Si, Zr and Mn also provides benefits, such as reducing the modulus of elasticity, increasing corrosion resistance and improving biocompatibility. In the present study, when choosing Ti-9Mo alloy, aluminum and copper (Cu) elements were added to it. These two alloys were chosen because one element is considered a favorable element for the body (copper) and the other element is harmful to the body (aluminum). By adding the copper alloy element to the Ti-9Mo alloy, the elastic modulus decreases to a minimum value of 97 GPa, and the aluminum alloy element increases the elastic modulus up to 118 GPa. Due to their similar properties, Ti-Mo-Cu alloys are found to be a good optional alloy to use. Full article

(This article belongs to the Special Issue Biomaterials, Biodevices and Tissue Engineering)

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25 pages, 7015 KiB

Open AccessReview

A Review of Photonic Sensors Based on Ring Resonator Structures: Three Widely Used Platforms and Implications of Sensing Applications

by Nikolay L. Kazanskiy, Svetlana N. Khonina and Muhammad A. Butt

Micromachines 2023, 14(5), 1080; https://doi.org/10.3390/mi14051080 - 20 May 2023

Cited by 8 | Viewed by 4005

Abstract

Optical ring resonators (RRs) are a novel sensing device that has recently been developed for several sensing applications. In this review, RR structures based on three widely explored platforms, namely silicon-on-insulator (SOI), polymers, and plasmonics, are reviewed. The adaptability of these platforms allows [...] Read more.

Optical ring resonators (RRs) are a novel sensing device that has recently been developed for several sensing applications. In this review, RR structures based on three widely explored platforms, namely silicon-on-insulator (SOI), polymers, and plasmonics, are reviewed. The adaptability of these platforms allows for compatibility with different fabrication processes and integration with other photonic components, providing flexibility in designing and implementing various photonic devices and systems. Optical RRs are typically small, making them suitable for integration into compact photonic circuits. Their compactness allows for high device density and integration with other optical components, enabling complex and multifunctional photonic systems. RR devices realized on the plasmonic platform are highly attractive, as they offer extremely high sensitivity and a small footprint. However, the biggest challenge to overcome is the high fabrication demand related to such nanoscale devices, which limits their commercialization. Full article

(This article belongs to the Special Issue Photonic and Optoelectronic Devices and Systems)

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13 pages, 9042 KiB

Open AccessArticle

Study of Gas Film Characteristics in Electrochemical Discharge Machining and Their Effects on Discharge Energy Distribution

by Hao Liu and Adayi Xieeryazidan

Micromachines 2023, 14(5), 1079; https://doi.org/10.3390/mi14051079 - 20 May 2023

Cited by 3 | Viewed by 1070

Abstract

Glass is a hard and brittle insulating material that is widely used in optics, biomedicine, and microelectromechanical systems. The electrochemical discharge process, which involves an effective microfabrication technology for insulating hard and brittle materials, can be used to perform effective microstructural processing on [...] Read more.

Glass is a hard and brittle insulating material that is widely used in optics, biomedicine, and microelectromechanical systems. The electrochemical discharge process, which involves an effective microfabrication technology for insulating hard and brittle materials, can be used to perform effective microstructural processing on glass. The gas film is the most important medium in this process, and its quality is an important factor in the formation of good surface microstructures. This study focuses on the gas film properties and their influence on the discharge energy distribution. In this study, a complete factorial design of experiments (DOE) was used, with three factors and three levels of voltage, duty cycle, and frequency as the influencing factors and gas film thickness as the response for the experimental study, to obtain the best combination of process parameters that would result in the best gas film quality. In addition, experiments and simulations of microhole processing on two types of glass, quartz glass and K9 optical glass, were conducted for the first time to characterize the discharge energy distribution of the gas film based on the radial overcut, depth-to-diameter ratio, and roundness error, and to analyze the gas film characteristics and their effects on the discharge energy distribution. The experimental results demonstrated the optimal combination of process parameters, at a voltage of 50 V, a frequency of 20 kHz and a duty cycle of 80%, that achieved a better gas film quality and a more uniform discharge energy distribution. A thin and stable gas film with a thickness of 189

μ

m was obtained with the optimal combination of parameters, which was 149

μ

m less than the extreme combination of parameters (60 V, 25 kHz, 60%). These studies resulted in an 81

μ

m reduction in radial overcut, a roundness error reduced by 14, and a 49% increase in the depth–shallow ratio for a microhole machined on quartz glass. Full article

(This article belongs to the Special Issue Micro-electro Discharge Machining: Principles, Recent Advancements and Applications, 3rd Edition)

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17 pages, 6712 KiB

Open AccessArticle

Mixing Performance of a Passive Micromixer Based on Multiple Baffles and Submergence Scheme

by Makhsuda Juraeva and Dong-Jin Kang

Micromachines 2023, 14(5), 1078; https://doi.org/10.3390/mi14051078 - 19 May 2023

Cited by 2 | Viewed by 1358

Abstract

A novel passive micromixer based on multiple baffles and a submergence scheme was designed, and its mixing performance was simulated over a wide range of Reynolds numbers ranging from 0.1 to 80. The degree of mixing (DOM) at the outlet and [...] Read more.

A novel passive micromixer based on multiple baffles and a submergence scheme was designed, and its mixing performance was simulated over a wide range of Reynolds numbers ranging from 0.1 to 80. The degree of mixing (DOM) at the outlet and the pressure drop between the inlets and outlet were used to assess the mixing performance of the present micromixer. The mixing performance of the present micromixer showed a significant enhancement over a wide range of Reynolds numbers (0.1 ≤ Re ≤ 80). The DOM was further enhanced by using a specific submergence scheme. At low Reynolds numbers (Re < 5), submergence scheme Sub24 produced the highest DOM, approximately 0.57, which was 1.38 times higher than the case with no submergence. This enhancement was due to the fluid flowing from or toward the submerged space, creating strong upward or downward flow at the cross-section. At high Reynolds numbers (Re > 10), the DOM of Sub1234 became the highest, reaching approximately 0.93 for Re = 20, which was 2.75 times higher than the case with no submergence. This enhancement was caused by a large vortex formed across the whole cross-section, causing vigorous mixing between the two fluids. The large vortex dragged the interface between the two fluids along the vortex perimeter, elongating the interface. The amount of submergence was optimized in terms of DOM, and it was independent of the number of mixing units. The optimum submergence values were 90 μm for Sub24 and Re = 1, 100 μm for Sub234 and Re = 5, and 70 μm for Sub1234 and Re = 20. Full article

(This article belongs to the Special Issue Microreactor Chips: Design, Fabrication, and Cutting-Edge Applications)

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13 pages, 5630 KiB

Open AccessArticle

Design of a Digital LAMP Detection Platform Based on Droplet Microfluidic Technology

by Liying Jiang, Xianghao Lan, Linjiao Ren, Mingzhu Yang, Bo Wei and Yang Wang

Micromachines 2023, 14(5), 1077; https://doi.org/10.3390/mi14051077 - 19 May 2023

Cited by 1 | Viewed by 1501

Abstract

Loop-mediated isothermal amplification (LAMP) is a rapid and high-yield amplification technology for specific DNA or RNA molecules. In this study, we designed a digital loop-mediated isothermal amplification (digital-LAMP)-functioning microfluidic chip to achieve higher sensitivity for detection of nucleic acids. The chip could generate [...] Read more.

Loop-mediated isothermal amplification (LAMP) is a rapid and high-yield amplification technology for specific DNA or RNA molecules. In this study, we designed a digital loop-mediated isothermal amplification (digital-LAMP)-functioning microfluidic chip to achieve higher sensitivity for detection of nucleic acids. The chip could generate droplets and collect them, based on which we could perform Digital-LAMP. The reaction only took 40 min at a constant temperature of 63 °C. The chip enabled highly accurate quantitative detection, with the limit of detection (LOD) down to 10² copies μL⁻¹. For better performance while reducing the investment of money and time in chip structure iterations, we used COMSOL Multiphysics to simulate different droplet generation ways by including flow-focusing structure and T-junction structure. Moreover, the linear structure, serpentine structure, and spiral structure in the microfluidic chip were compared to study the fluid velocity and pressure distribution. The simulations provided a basis for chip structure design while facilitating chip structure optimization. The digital-LAMP-functioning chip proposed in the work provides a universal platform for analysis of viruses. Full article

(This article belongs to the Special Issue Micro/Nanofluidics Devices for Nucleic Acids and Cell Analysis)

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12 pages, 2090 KiB

Open AccessArticle

Ultra-Fast Impedimetric Immunoassay for Detection of Streptococcus agalactiae Using Carbon Electrode with Nanodiamonds Film

by Daniel Bigus, Wioleta Lewandowska, Ewelina Bięga, Anna Grela, Aleksandra Siedlar, Marta Sosnowska, Magdalena Fabisiak, Tomasz Łęga, Yanina Dashkievich, Joanna Nowacka-Dośpiał, Katarzyna Palka, Sabina Żołędowska and Dawid Nidzworski

Micromachines 2023, 14(5), 1076; https://doi.org/10.3390/mi14051076 - 19 May 2023

Viewed by 1240

Abstract

This publication presents the results of work on the development of a quick and cheap electrochemical immunosensor for the diagnosis of infections with the pathogen Streptococcus agalactiae. The research was carried out on the basis of the modification of the well-known glassy [...] Read more.

This publication presents the results of work on the development of a quick and cheap electrochemical immunosensor for the diagnosis of infections with the pathogen Streptococcus agalactiae. The research was carried out on the basis of the modification of the well-known glassy carbon (GC) electrodes. The surface of the GC (glassy carbon) electrode was covered with a film made of nanodiamonds, which increased the number of sites for the attachment of anti-Streptococcus agalactiae antibodies. The GC surface was activated with EDC/NHS (1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-Hydroxysuccinimide). Determination of electrode characteristics after each modification step, performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Full article

(This article belongs to the Section B：Biology and Biomedicine)

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11 pages, 4030 KiB

Open AccessArticle

Upconversion Luminescence Response of a Single YVO₄:Yb, Er Particle

by Dmitry K. Zharkov, Andrey V. Leontyev, Artemi G. Shmelev, Larisa A. Nurtdinova, Anton P. Chuklanov, Niaz I. Nurgazizov and Victor G. Nikiforov

Micromachines 2023, 14(5), 1075; https://doi.org/10.3390/mi14051075 - 19 May 2023

Cited by 1 | Viewed by 1340

Abstract

We present the results of the luminescence response studies of a single YVO₄:Yb, Er particle of 1-µm size. Yttrium vanadate nanoparticles are well-known for their low sensitivity to surface quenchers in water solutions which makes them of special interest for biological [...] Read more.

We present the results of the luminescence response studies of a single YVO₄:Yb, Er particle of 1-µm size. Yttrium vanadate nanoparticles are well-known for their low sensitivity to surface quenchers in water solutions which makes them of special interest for biological applications. First, YVO₄:Yb, Er nanoparticles (in the size range from 0.05 µm up to 2 µm), using the hydrothermal method, were synthesized. Nanoparticles deposited and dried on a glass surface exhibited bright green upconversion luminescence. By means of an atomic-force microscope, a 60 × 60 µm² square of a glass surface was cleaned from any noticeable contaminants (more than 10 nm in size) and a single particle of 1-µm size was selected and placed in the middle. Confocal microscopy revealed a significant difference between the collective luminescent response of an ensemble of synthesized nanoparticles (in the form of a dry powder) and that of a single particle. In particular, a pronounced polarization of the upconversion luminescence from a single particle was observed. Luminescence dependences on the laser power are quite different for the single particle and the large ensemble of nanoparticles as well. These facts attest to the notion that upconversion properties of single particles are highly individual. This implies that to use an upconversion particle as a single sensor of the local parameters of a medium, the additional studying and calibration of its individual photophysical properties are essential. Full article

(This article belongs to the Special Issue Semiconductors and Nanostructures for Electronics and Photonics)

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22 pages, 20434 KiB

Open AccessArticle

Simulation Studies on Single-Event Effects and the Mechanisms of SiC VDMOS from a Structural Perspective

by Tao Liu, Yuan Wang, Rongyao Ma, Hao Wu, Jingyu Tao, Yiren Yu, Zijun Cheng and Shengdong Hu

Micromachines 2023, 14(5), 1074; https://doi.org/10.3390/mi14051074 - 18 May 2023

Cited by 1 | Viewed by 1204

Abstract

The single-event effect reliability issue is one of the most critical concerns in the context of space applications for SiC VDMOS. In this paper, the SEE characteristics and mechanisms of the proposed deep trench gate superjunction (DTSJ), conventional trench gate superjunction (CTSJ), conventional [...] Read more.

The single-event effect reliability issue is one of the most critical concerns in the context of space applications for SiC VDMOS. In this paper, the SEE characteristics and mechanisms of the proposed deep trench gate superjunction (DTSJ), conventional trench gate superjunction (CTSJ), conventional trench gate (CT), and conventional planar gate (CT) SiC VDMOS are comprehensively analyzed and simulated. Extensive simulations demonstrate the maximum SET current peaks of DTSJ−, CTSJ−, CT−, and CP SiC VDMOS, which are 188 mA, 218 mA, 242 mA, and 255 mA, with a bias voltage V_DS of 300 V and LET = 120 MeV·cm²/mg, respectively. The total charges of DTSJ−, CTSJ−, CT−, and CP SiC VDMOS collected at the drain are 320 pC, 1100 pC, 885 pC, and 567 pC, respectively. A definition and calculation of the charge enhancement factor (CEF) are proposed. The CEF values of DTSJ−, CTSJ−, CT−, and CP SiC VDMOS are 43, 160, 117, and 55, respectively. Compared with CTSJ−, CT−, and CP SiC VDMOS, the total charge and CEF of the DTSJ SiC VDMOS are reduced by 70.9%, 62.4%, 43.6% and 73.1%, 63.2%, and 21.8%, respectively. The maximum SET lattice temperature of the DTSJ SiC VDMOS is less than 2823 K under the wide operating conditions of a drain bias voltage V_DS ranging from 100 V to 1100 V and a LET value ranging from 1 MeV·cm²/mg to 120 MeV·cm²/mg, while the maximum SET lattice temperatures of the other three SiC VDMOS significantly exceed 3100 K. The SEGR LET thresholds of DTSJ−, CTSJ−, CT−, and CP SiC VDMOS are approximately 100 MeV·cm²/mg, 15 MeV·cm²/mg, 15 MeV·cm²/mg, and 60 MeV·cm²/mg, respectively, while the value of V_DS = 1100 V. Full article

(This article belongs to the Special Issue Power Semiconductor Devices and Applications)

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9 pages, 2932 KiB

Open AccessCommunication

On-Chip E₀₀–E₂₀ Mode Converter Based on Multi-Mode Interferometer

by Yuan Zhang, Yuexin Yin, Yingzhi Ding, Shengyuan Zhang, Xiaoqiang Sun, Daming Zhang and Ye Li

Micromachines 2023, 14(5), 1073; https://doi.org/10.3390/mi14051073 - 18 May 2023

Viewed by 1074

Abstract

Mode converters is a key component in mode-division multiplexing (MDM) systems, which plays a key role in signal processing and multi-mode conversion. In this paper, we propose an MMI-based mode converter on 2%-Δ silica PLC platform. The converter transfers E₀₀ mode to [...] Read more.

Mode converters is a key component in mode-division multiplexing (MDM) systems, which plays a key role in signal processing and multi-mode conversion. In this paper, we propose an MMI-based mode converter on 2%-Δ silica PLC platform. The converter transfers E₀₀ mode to E₂₀ mode with high fabrication tolerance and large bandwidth. The experimental results show that the conversion efficiency can exceed −1.741 dB with the wavelength range of 1500 nm to 1600 nm. The measured conversion efficiency of the mode converter can reach −0.614 dB at 1550 nm. Moreover, the degradation of conversion efficiency is less than 0.713 dB under the deviation of multimode waveguide length and phase shifter width at 1550 nm. The proposed broadband mode converter with high fabrication tolerance is promising for on-chip optical network and commercial applications. Full article

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18 pages, 10262 KiB

Open AccessArticle

Heat Transfer Enhancement Using Al₂O₃-MWCNT Hybrid-Nanofluid inside a Tube/Shell Heat Exchanger with Different Tube Shapes

by Maissa Bouselsal, Fateh Mebarek-Oudina, Nirmalendu Biswas and Abdel Aziz I. Ismail

Micromachines 2023, 14(5), 1072; https://doi.org/10.3390/mi14051072 - 18 May 2023

Cited by 38 | Viewed by 2087

Abstract

The high demand for compact heat exchangers has led researchers to develop high-quality and energy-efficient heat exchangers at a lower cost than conventional ones. To address this requirement, the present study focuses on improvements to the tube/shell heat exchanger to maximize the efficiency [...] Read more.

The high demand for compact heat exchangers has led researchers to develop high-quality and energy-efficient heat exchangers at a lower cost than conventional ones. To address this requirement, the present study focuses on improvements to the tube/shell heat exchanger to maximize the efficiency either by altering the tube’s geometrical shape and/or by adding nanoparticles in its heat transfer fluid. Water-based Al₂O₃-MWCNT hybrid nanofluid is utilized here as a heat transfer fluid. The fluid flows at a high temperature and constant velocity, and the tubes are maintained at a low temperature with various shapes of the tube. The involved transport equations are solved numerically by the finite-element-based computing tool. The results are presented using the streamlines, isotherms, entropy generation contours, and Nusselt number profiles for various nanoparticles volume fraction 0.01 ≤ φ ≤ 0.04 and Reynolds numbers 2400 ≤ Re ≤ 2700 for the different shaped tubes of the heat exchanger. The results indicate that the heat exchange rate is a growing function of the increasing nanoparticle concentration and velocity of the heat transfer fluid. The diamond-shaped tubes show a better geometric shape for obtaining the superior heat transfer of the heat exchanger. Heat transfer is further enhanced by using the hybrid nanofluid, and the enhancement goes up to 103.07% with a particle concentration of 2%. The corresponding entropy generation is also minimal with the diamond-shaped tubes. The outcome of the study is very significant in the industrial field and can solve many heat transfer problems. Full article

(This article belongs to the Special Issue Heat Transfer and Fluid Flow in Microstructures)

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16 pages, 30694 KiB

Open AccessArticle

A Dual-Polarized Omnidirectional Rectenna Array for RF Energy Harvesting

by Yong Wang, Ningning Lu, Hucheng Sun and Rui Ren

Micromachines 2023, 14(5), 1071; https://doi.org/10.3390/mi14051071 - 18 May 2023

Cited by 4 | Viewed by 1315

Abstract

In this paper, a dual-polarized omnidirectional rectenna array using a hybrid power-combining scheme is proposed for the applications of RF energy harvesting. In the antenna design part, two omnidirectional antenna subarrays are created to receive horizontally polarized electromagnetic (EM) waves and a four-dipole [...] Read more.

In this paper, a dual-polarized omnidirectional rectenna array using a hybrid power-combining scheme is proposed for the applications of RF energy harvesting. In the antenna design part, two omnidirectional antenna subarrays are created to receive horizontally polarized electromagnetic (EM) waves and a four-dipole subarray is produced to receive vertically polarized incoming EM waves. The two antenna subarrays of different polarizations are combined and optimized, so as to reduce the mutual influence between them. In this way, a dual-polarized omnidirectional antenna array is realized. In the rectifier design part, a half-wave rectifying structure is adopted for converting the RF energy into DC energy. Based on the Wilkinson power divider and 3-dB hybrid coupler structure, a power-combining network is designed to connect the whole antenna array and rectifiers. The proposed rectenna array is fabricated and measured under different RF energy harvesting scenarios. All simulated and measured results are in good agreement, which verifies the capabilities of the designed rectenna array. Full article

(This article belongs to the Special Issue Advanced Antenna System: Structural Analysis, Design and Application)

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21 pages, 6271 KiB

Open AccessArticle

Robust Attitude and Heading Estimation under Dynamic Motion and Magnetic Disturbance

by Fan Bo, Jia Li, Weibing Wang and Kaiyue Zhou

Micromachines 2023, 14(5), 1070; https://doi.org/10.3390/mi14051070 - 18 May 2023

Cited by 2 | Viewed by 1502

Abstract

Robust and accurate attitude and heading estimation using Micro-Electromechanical System (MEMS) Inertial Measurement Units (IMU) is the most crucial technique that determines the accuracy of various downstream applications, especially pedestrian dead reckoning (PDR), human motion tracking, and Micro Aerial Vehicles (MAVs). However, the [...] Read more.

Robust and accurate attitude and heading estimation using Micro-Electromechanical System (MEMS) Inertial Measurement Units (IMU) is the most crucial technique that determines the accuracy of various downstream applications, especially pedestrian dead reckoning (PDR), human motion tracking, and Micro Aerial Vehicles (MAVs). However, the accuracy of the Attitude and Heading Reference System (AHRS) is often compromised by the noisy nature of low-cost MEMS-IMUs, dynamic motion-induced large external acceleration, and ubiquitous magnetic disturbance. To address these challenges, we propose a novel data-driven IMU calibration model that employs Temporal Convolutional Networks (TCNs) to model random errors and disturbance terms, providing denoised sensor data. For sensor fusion, we use an open-loop and decoupled version of the Extended Complementary Filter (ECF) to provide accurate and robust attitude estimation. Our proposed method is systematically evaluated using three public datasets, TUM VI, EuRoC MAV, and OxIOD, with different IMU devices, hardware platforms, motion modes, and environmental conditions; and it outperforms the advanced baseline data-driven methods and complementary filter on two metrics, namely absolute attitude error and absolute yaw error, by more than 23.4% and 23.9%. The generalization experiment results demonstrate the robustness of our model on different devices and using patterns. Full article

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15 pages, 5747 KiB

Open AccessCommunication

A High-Sensitivity MEMS Accelerometer Using a Sc_0.8Al_0.2N-Based Four Beam Structure

by Zhenghu Zhang, Linwei Zhang, Zhipeng Wu, Yunfei Gao and Liang Lou

Micromachines 2023, 14(5), 1069; https://doi.org/10.3390/mi14051069 - 18 May 2023

Cited by 2 | Viewed by 1915

Abstract

In this paper, a high-sensitivity microelectromechanical system (MEMS) piezoelectric accelerometer based on a Scandium-doped Aluminum Nitride (ScAlN) thin film is proposed. The primary structure of this accelerometer is a silicon proof mass fixed by four piezoelectric cantilever beams. In order to enhance the [...] Read more.

In this paper, a high-sensitivity microelectromechanical system (MEMS) piezoelectric accelerometer based on a Scandium-doped Aluminum Nitride (ScAlN) thin film is proposed. The primary structure of this accelerometer is a silicon proof mass fixed by four piezoelectric cantilever beams. In order to enhance the sensitivity of the accelerometer, the Sc_0.2Al_0.8N piezoelectric film is used in the device. The transverse piezoelectric coefficient d₃₁ of the Sc_0.2Al_0.8N piezoelectric film is measured by the cantilever beam method and found to be −4.7661 pC/N, which is approximately two to three times greater than that of a pure AlN film. To further enhance the sensitivity of the accelerometer, the top electrodes are divided into inner and outer electrodes; then, the four piezoelectric cantilever beams can achieve a series connection by these inner and outer electrodes. Subsequently, theoretical and finite element models are established to analyze the effectiveness of the above structure. After fabricating the device, the measurement results demonstrate that the resonant frequency of the device is 7.24 kHz and the operating frequency is 56 Hz to 2360 Hz. At a frequency of 480 Hz, the sensitivity, minimum detectable acceleration, and resolution of the device are 2.448 mV/g, 1 mg, and 1 mg, respectively. The linearity of the accelerometer is good for accelerations less than 2 g. The proposed piezoelectric MEMS accelerometer has demonstrated high sensitivity and linearity, making it suitable for accurately detecting low-frequency vibrations. Full article

(This article belongs to the Special Issue Design, Fabrication and Testing of MEMS/NEMS, 2nd Edition)

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10 pages, 6663 KiB

Open AccessArticle

Design and Realization of Polymeric Waveguide/Microring Structures for Telecommunication Domain

by Thuy Linh La, Binh Nguyen Bui, Thi Thanh Ngan Nguyen, Thi Lien Pham, Quoc Tien Tran, Quang Cong Tong, Aliaksandr Mikulich, Thanh Phuong Nguyen, Thi Thu Thuy Nguyen and Ngoc Diep Lai

Micromachines 2023, 14(5), 1068; https://doi.org/10.3390/mi14051068 - 18 May 2023

Cited by 1 | Viewed by 1312

Abstract

Polymer-based micro-optical components are very important for applications in optical communication. In this study, we theoretically investigated the coupling of polymeric waveguide and microring structures and experimentally demonstrated an efficient fabrication method to realize these structures on demand. First, the structures were designed [...] Read more.

Polymer-based micro-optical components are very important for applications in optical communication. In this study, we theoretically investigated the coupling of polymeric waveguide and microring structures and experimentally demonstrated an efficient fabrication method to realize these structures on demand. First, the structures were designed and simulated using the FDTD method. The optical mode and loss in the coupling structures were calculated, thereby giving the optimal distance for optical mode coupling between two rib waveguide structures or for optical mode coupling in a microring resonance structure. Simulations results then guided us in the fabrication of the desired ring resonance microstructures using a robust and flexible direct laser writing technique. The entire optical system was thus designed and manufactured on a flat base plate so that it could be easily integrated in optical circuits. Full article

(This article belongs to the Special Issue Laser Micro/Nano Fabrication)

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4 pages, 208 KiB

Open AccessEditorial

Editorial for Special Issue “Piezoelectric Aluminium Scandium Nitride (AlScN) Thin Films: Material Development and Applications in Microdevices”

by Agnė Žukauskaitė

Micromachines 2023, 14(5), 1067; https://doi.org/10.3390/mi14051067 - 18 May 2023

Viewed by 1709

Abstract

The enhanced piezoelectric properties of aluminum scandium nitride (Al_1−xSc_xN or AlScN) were discovered in 2009 by Morito Akiyama’s team [...] Full article

(This article belongs to the Special Issue Piezoelectric Aluminium Scandium Nitride (AlScN) Thin Films: Material Development and Applications in Microdevices)

15 pages, 2983 KiB

Open AccessArticle

Broadband and Efficient Metamaterial Absorber Design Based on Gold–MgF2–Tungsten Hybrid Structure for Solar Thermal Application

by Ammar Armghan, Meshari Alsharari and Khaled Aliqab

Micromachines 2023, 14(5), 1066; https://doi.org/10.3390/mi14051066 - 17 May 2023

Cited by 1 | Viewed by 1070

Abstract

We have presented a solar absorber design with gold–MgF₂–tungsten materials. The solar absorber design is optimized with nonlinear optimization mathematical method to find and optimize geometrical parameters. The wideband absorber is made of a three-layer structure composed of tungsten, magnesium fluoride, [...] Read more.

We have presented a solar absorber design with gold–MgF₂–tungsten materials. The solar absorber design is optimized with nonlinear optimization mathematical method to find and optimize geometrical parameters. The wideband absorber is made of a three-layer structure composed of tungsten, magnesium fluoride, and gold. This study analyzed the absorber’s performance using numerical methods over the sun wavelength range of 0.25 μm to 3 μm. The solar AM 1.5 absorption spectrum is a benchmark against which the proposed structure’s absorbing characteristics are evaluated and discussed. It is necessary to analyze the behavior of the absorber under a variety of various physical parameter conditions in order to determine the results and structural dimensions that are optimal. The nonlinear parametric optimization algorithm is applied to obtain the optimized solution. This structure can absorb more than 98% of light across the near-infrared and visible light spectrums. In addition, the structure has a high absorption efficiency for the far range of the infrared spectrum and the THz range. The absorber that has been presented is versatile enough to be used in a variety of solar applications, both narrowband and broadband. The design of the solar cell that has been presented will be of assistance in designing a solar cell that has high efficiency. The proposed optimized design with optimized parameters will help design solar thermal absorbers. Full article

(This article belongs to the Special Issue Graphene-Based Metamaterial Solar Energy Devices)

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13 pages, 4930 KiB

Open AccessCommunication

Temperature Performance Study of SAW Sensors Based on AlN and AlScN

by Hui Wang, Linwei Zhang, Zhixin Zhou and Liang Lou

Micromachines 2023, 14(5), 1065; https://doi.org/10.3390/mi14051065 - 17 May 2023

Cited by 3 | Viewed by 1529

Abstract

In this paper, the temperature performance of AlN-SAW resonators and AlScN-SAW resonators is studied. They are simulated by COMSOL Multiphysics, and their modes and the S11 curve are analyzed. The two devices were fabricated using MEMS technology and tested using VNA, and the [...] Read more.

In this paper, the temperature performance of AlN-SAW resonators and AlScN-SAW resonators is studied. They are simulated by COMSOL Multiphysics, and their modes and the S11 curve are analyzed. The two devices were fabricated using MEMS technology and tested using VNA, and the test results were consistent with the simulation results. Temperature experiments were carried out with temperature control equipment. With the change in temperature, the changes in S11 parameters, TCF coefficient, phase velocity, and quality factor Q were analyzed. The results show that the temperature performance of the AlN-SAW resonator and the AlScN-SAW resonator is very good, and both have good linearity. At the same time, the sensitivity of the AlScN-SAW resonator is greater by 9.5%, the linearity is greater by 15%, and the TCF coefficient is greater by 11.1%. The temperature performance is excellent, and it is more suitable as a temperature sensor. Full article

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Micromachines, Volume 14, Issue 5 (May 2023) – 198 articles

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