Next Issue
Volume 14, January
Previous Issue
Volume 13, November
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
4.7
3.4
Journals
Micromachines
Volume 13
Issue 12
share announcement

Micromachines, Volume 13, Issue 12 (December 2022) – 224 articles

Cover Story (view full-size image): Image-based cell sorting is essential in biological and biomedical research. The sorted cells can be used for downstream analysis to expand our knowledge of cell-to-cell differences. We previously demonstrated a user-friendly image-activated microfluidic cell sorting technique using an optimized and fast deep learning algorithm. In this study, we devised a recently upgraded sorting system. The cell sorting techniques shown on the microscope were implemented as a real system. Several new features were added to make it easier for the users to conduct the real-time sorting of cells or particles. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
13 pages, 14364 KiB  
Article
Bimorph Dual-Electrode ScAlN PMUT with Two Terminal Connections
by Meilin Ji, Haolin Yang, Yongxin Zhou, Xueying Xiu, Haochen Lv and Songsong Zhang
Micromachines 2022, 13(12), 2260; https://doi.org/10.3390/mi13122260 - 19 Dec 2022
Cited by 6 | Viewed by 2599
Abstract
This paper presents a novel bimorph Piezoelectric Micromachined Ultrasonic Transducer (PMUT) fabricated with 8-inch standard CMOS-compatible processes. The bimorph structure consists of two layers of 20% scandium-doped aluminum nitride (Sc0.2Al0.8N) thin films, which are sandwiched among three molybdenum (Mo) [...] Read more.
This paper presents a novel bimorph Piezoelectric Micromachined Ultrasonic Transducer (PMUT) fabricated with 8-inch standard CMOS-compatible processes. The bimorph structure consists of two layers of 20% scandium-doped aluminum nitride (Sc0.2Al0.8N) thin films, which are sandwiched among three molybdenum (Mo) layers. All three Mo layers are segmented to form the outer ring and inner plate electrodes. Both top and bottom electrodes on the outer ring are electrically linked to the center inner plate electrodes. Likewise, the top and bottom center plate electrodes are electrically connected to the outer ring in the same fashion. This electrical configuration maximizes the effective area of the given PMUT design and improves efficiency during the electromechanical coupling process. In addition, the proposed bimorph structure further simplifies the device’s electrical layout with only two-terminal connections as reported in many conventional unimorph PMUTs. The mechanical and acoustic measurements are conducted to verify the device’s performance improvement. The dynamic mechanical displacement and acoustic output under a low driving voltage (1 Vpp) are more than twice that reported from conventional unimorph devices with a similar resonant frequency. Moreover, the pulse-echo experiments indicate an improved receiving voltage of 10 mV in comparison with the unimorph counterpart (4.8 mV). The validation of device advancement in the electromechanical coupling effect by using highly doped ScAlN thin film, the realization of the proposed bimorph PMUT on an 8-inch wafer paves the path to production of next generation, high-performance piezoelectric MEMS. Full article
(This article belongs to the Special Issue Design, Fabrication, Testing of MEMS/NEMS)
►▼ Show Figures

Figure 1

17 pages, 4861 KiB  
Article
Dynamic and Functional Alterations of Neuronal Networks In Vitro upon Physical Damage: A Proof of Concept
by Sàlem Ayasreh, Imanol Jurado, Clara F. López-León, Marc Montalà-Flaquer and Jordi Soriano
Micromachines 2022, 13(12), 2259; https://doi.org/10.3390/mi13122259 - 19 Dec 2022
Cited by 2 | Viewed by 1373
Abstract
There is a growing technological interest in combining biological neuronal networks with electronic ones, specifically for biological computation, human–machine interfacing and robotic implants. A major challenge for the development of these technologies is the resilience of the biological networks to physical damage, for [...] Read more.
There is a growing technological interest in combining biological neuronal networks with electronic ones, specifically for biological computation, human–machine interfacing and robotic implants. A major challenge for the development of these technologies is the resilience of the biological networks to physical damage, for instance, when used in harsh environments. To tackle this question, here, we investigated the dynamic and functional alterations of rodent cortical networks grown in vitro that were physically damaged, either by sequentially removing groups of neurons that were central for information flow or by applying an incision that cut the network in half. In both cases, we observed a remarkable capacity of the neuronal cultures to cope with damage, maintaining their activity and even reestablishing lost communication pathways. We also observed—particularly for the cultures cut in half—that a reservoir of healthy neurons surrounding the damaged region could boost resilience by providing stimulation and a communication bridge across disconnected areas. Our results show the remarkable capacity of neuronal cultures to sustain and recover from damage, and may be inspirational for the development of future hybrid biological–electronic systems. Full article
(This article belongs to the Special Issue Recent Advance in Medical and Rehabilitation Robots)
►▼ Show Figures

Figure 1

22 pages, 4757 KiB  
Review
Recent Progress in Thin-Film Transistors toward Digital, Analog, and Functional Circuits
by Seongjae Kim and Hocheon Yoo
Micromachines 2022, 13(12), 2258; https://doi.org/10.3390/mi13122258 - 19 Dec 2022
Viewed by 2402
Abstract
Thin-film transistors have been extensively developed due to their process merit: high compatibility with various substrates, large-area processes, and low-cost processes. Despite these advantages, most efforts for thin-film transistors still remain at the level of unit devices, so the circuit level for practical [...] Read more.
Thin-film transistors have been extensively developed due to their process merit: high compatibility with various substrates, large-area processes, and low-cost processes. Despite these advantages, most efforts for thin-film transistors still remain at the level of unit devices, so the circuit level for practical use needs to be further developed. In this regard, this review revisits digital and analog thin-film circuits using carbon nanotubes (CNTs), organic electrochemical transistors (OECTs), organic semiconductors, metal oxides, and two-dimensional materials. This review also discusses how to integrate thin-film circuits at the unit device level and some key issues such as metal routing and interconnection. Challenges and opportunities are also discussed to pave the way for developing thin-film circuits and their practical applications. Full article
(This article belongs to the Special Issue Memristive Devices & Thin-Film Transistors: Design, Fabrication and Applications)
►▼ Show Figures

Figure 1

11 pages, 4478 KiB  
Article
Terahertz Combined with Metamaterial Microfluidic Chip for Troponin Antigen Detection
by Yen-Shuo Lin, Shih-Ting Huang, Shen-Fu Hsu, Kai-Yuan Tang, Ta-Jen Yen and Da-Jeng Yao
Micromachines 2022, 13(12), 2257; https://doi.org/10.3390/mi13122257 - 19 Dec 2022
Cited by 2 | Viewed by 1425
Abstract
In this paper, we use terahertz combined with metamaterial technology as a powerful tool to identify analytes at different concentrations. Combined with the microfluidic chip, the experimental measurement can be performed with a small amount of analyte. In detecting the troponin antigen, surface [...] Read more.
In this paper, we use terahertz combined with metamaterial technology as a powerful tool to identify analytes at different concentrations. Combined with the microfluidic chip, the experimental measurement can be performed with a small amount of analyte. In detecting the troponin antigen, surface modification is carried out by biochemical binding. Through the observation of fluorescent antibodies, the average number of fluorescent dots per unit of cruciform metamaterial is 25.60, and then, by adjusting the binding temperature and soaking time, the average number of fluorescent dots per unit of cruciform metamaterial can be increased to 181.02. Through the observation of fluorescent antibodies, it is confirmed that the antibodies can be successfully stabilized on the metamaterial and then bound to the target antigen. The minimum detectable concentration is between 0.05~0.1 μg/100 μL, and the concentration and ΔY show a positive correlation of R2 = 0.9909. Full article
(This article belongs to the Special Issue Nano- and Microfluidic Materials and Systems)
►▼ Show Figures

Figure 1

12 pages, 2029 KiB  
Article
Stainless Steel Foil-Based Label-Free Modular Thin-Film Electrochemical Detector for Solvent Identification
by Martin Rozman and Miha Lukšič
Micromachines 2022, 13(12), 2256; https://doi.org/10.3390/mi13122256 - 19 Dec 2022
Viewed by 1253
Abstract
Most organic solvents are colorless liquids, usually stored in sealed containers. In many cases, their identification depends on the appropriate description on the container to prevent mishandling or mixing with other materials. Although modern laboratories rely heavily on identification technologies, such as digitized [...] Read more.
Most organic solvents are colorless liquids, usually stored in sealed containers. In many cases, their identification depends on the appropriate description on the container to prevent mishandling or mixing with other materials. Although modern laboratories rely heavily on identification technologies, such as digitized inventories and spectroscopic methods (e.g., NMR or FTIR), there may be situations where these cannot be used due to technical failure, lack of equipment, or time. An example of a portable and cost-effective solution to this problem is an electrochemical sensor. However, these are often limited to electrochemical impedance spectroscopy (EIS) or voltammetry methods. To address this problem, we present a novel modular electrochemical sensor for solvent identification that can be used with either an EIS-enabled potentiostat/galvanostat or a simple multimeter. A novel method of fabricating and using a sensor consisting of a thin-film coating of an organic substance on a stainless-steel electrode substrate is presented. The differences in the solubility of the thin film in different solvents are used to distinguish between common organic solvents such as water, ethanol, and tetrahydrofuran. Full article
(This article belongs to the Special Issue Miniaturized Chemical Sensors)
►▼ Show Figures

Figure 1

12 pages, 6577 KiB  
Article
Liquid-Metal-Based Magnetic Controllable Soft Microswitch with Rapid and Reliable Response for Intelligent Soft Systems
by Qin Jiang, Zhitong Hu, Yaping Xie, Kefan Wu, Shuo Zhang and Zhigang Wu
Micromachines 2022, 13(12), 2255; https://doi.org/10.3390/mi13122255 - 18 Dec 2022
Cited by 1 | Viewed by 1418
Abstract
When combined with diverse sensors, soft robots significantly improve their functionalities and intelligence levels. However, most of the existing soft sensors require complex signal analysis devices or algorithms, which severely increase the complexity of soft robot systems. Here, based on the unique fluidic [...] Read more.
When combined with diverse sensors, soft robots significantly improve their functionalities and intelligence levels. However, most of the existing soft sensors require complex signal analysis devices or algorithms, which severely increase the complexity of soft robot systems. Here, based on the unique fluidic property of liquid metal, we propose a magnet-controllable soft microswitch that can be well-integrated into a soft robot system, e.g., a soft gripper to help it facilely detect and precisely grab objects. The microswitch consists of a flexible soft beam electrode and a fixed electrode, forming a soft microsystem. By tuning the cohesion force of the liquid metal between the electrodes, the microswitch can convert its states between an individual and a self-locking state. The microswitch can achieve a reasonable rapid response (~12 ms) and high switching frequency (~95 Hz). Furthermore, soft microswitches can be customized into logic units and also coupled to control a digital tube showing various numbers. Our work provides a new simple soft sensor unit that may enhance the intelligence of soft systems. Full article
(This article belongs to the Section A：Physics)
►▼ Show Figures

Figure 1

16 pages, 4520 KiB  
Article
Preparation, Characterization and Magneto-Optical Properties of Sm-Doped Y2O3 Polycrystalline Material
by Andrzej Kruk and Krzysztof Ziewiec
Micromachines 2022, 13(12), 2254; https://doi.org/10.3390/mi13122254 - 18 Dec 2022
Cited by 5 | Viewed by 1545
Abstract
In this paper, physicochemical properties of pure Y2O3 and samarium (Sm)-doped Y2O3 transparent ceramics obtained via arc plasma melting are presented. Yttria powder with a selected molar fraction of Sm was first synthesized by a solid-state reaction [...] Read more.
In this paper, physicochemical properties of pure Y2O3 and samarium (Sm)-doped Y2O3 transparent ceramics obtained via arc plasma melting are presented. Yttria powder with a selected molar fraction of Sm was first synthesized by a solid-state reaction method. High transparent yttria ceramics were obtained by arc plasma melting from both the pure and Sm oxide-doped powders. The morphological, chemical and physical properties were investigated by X-ray diffraction and scanning electron microscopy. The optical band gap was calculated from the absorption spectra so as to understand the electronic band structure of the studied materials. Samples indicate a series of luminescence bands in the visible region after excitation by laser light in the range from 210 to 250 nm. Magneto-optical measurements were carried out in the 300–800 nm range at room temperature. It can be seen that a maximum Verdet constant ca. 24.81 deg/T cm was observed for 405 nm and this value decreases with increasing wavelength. The potential usefulness of the polycrystalline material dedicated to optics devices is presented. Full article
(This article belongs to the Special Issue Optics & Photonics—Micro and Nano Structures, Materials and Devices (AOP2022))
►▼ Show Figures

Figure 1

9 pages, 2356 KiB  
Article
Propagation Losses Estimation in a Cationic-Network-Based Hydrogel Waveguide
by Carolina Pons, Josué M. Galindo, Juan C. Martín, Iván Torres-Moya, Sonia Merino, M. Antonia Herrero, Ester Vázquez, Pilar Prieto and Juan A. Vallés
Micromachines 2022, 13(12), 2253; https://doi.org/10.3390/mi13122253 - 18 Dec 2022
Viewed by 1222
Abstract
A method based on the photographic recording of the power distribution laterally diffused by cationic-network (CN) hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to optical power attenuation along the hydrogel-based waveguide. Absorption [...] Read more.
A method based on the photographic recording of the power distribution laterally diffused by cationic-network (CN) hydrogel waveguides is first checked against the well-established cut-back method and then used to determine the different contributions to optical power attenuation along the hydrogel-based waveguide. Absorption and scattering loss coefficients are determined for 450 nm, 532 nm and 633 nm excitation. The excellent optical loss values obtained (0.32–1.95 dB/cm), similar to others previously described, indicate their potential application as waveguides in different fields, including soft robotic and light-based therapies. Full article
(This article belongs to the Special Issue Optics & Photonics—Micro and Nano Structures, Materials and Devices (AOP2022))
►▼ Show Figures

Figure 1

12 pages, 4074 KiB  
Article
Structural Optimization and Mechanical Simulation of MEMS Thin-Film Getter–Heater Unit
by Xinlin Peng, Yucheng Ji, Shuo Chen, Song Guo, Liuhaodong Feng, Yang Xu and Shinan Wang
Micromachines 2022, 13(12), 2252; https://doi.org/10.3390/mi13122252 - 18 Dec 2022
Cited by 1 | Viewed by 1481
Abstract
A MEMS thin-film getter–heater unit has been previously proposed for the vacuum packaging of a Micro-Electro-Mechanical System (MEMS) device, where the floating structure (FS) design is found to be obviously more power-efficient than the solid structure (SS) one by heat transfer capacity simulation. [...] Read more.
A MEMS thin-film getter–heater unit has been previously proposed for the vacuum packaging of a Micro-Electro-Mechanical System (MEMS) device, where the floating structure (FS) design is found to be obviously more power-efficient than the solid structure (SS) one by heat transfer capacity simulation. However, the mechanical strength of the FS is weaker than the SS by nature. For high temperature usage, the unit structure must be optimized in order to avoid fracture of the cantilever beam or film delamination due to strong excessive stress caused by heating. In this paper, COMSOL is used to simulate the stress and deformation of the MEMS thin-film getter–heater unit with the cantilever structure. By comparing various cantilever structures, it is found that a model with a symmetrically-shaped heater and edge–center-located cantilever model (II-ECLC model) is the most suitable. In this model, even when the structure is heated to about 600 °C, the maximum stress of the cantilever beam is only 455 MPa, much lower than the tensile strength of silicon nitride (Si3N4, 12 GPa), and the maximum deformation displacement is about 200 μm. Meanwhile, the interfacial stress between the getter and the insulating layer is 44 MPa, sufficiently lower than the adhesion strength between silicon nitride film and titanium film (400–1850 MPa). It is further found that both the stress of the cantilever structure and the interfacial stress between the getter and the insulating layer beneath increase linearly with temperature; and the deformation of the cantilever structure is proportional to its stress. This work gives guidance on the design of MEMS devices with cantilever structures and works in high temperature situations. Full article
(This article belongs to the Special Issue Design, Fabrication, Testing of MEMS/NEMS)
►▼ Show Figures

Figure 1

13 pages, 5667 KiB  
Article
Low Profile Meandered Printed Monopole WiMAX/WLAN Antenna for Laptop Computer Applications
by Killol Vishnuprasad Pandya
Micromachines 2022, 13(12), 2251; https://doi.org/10.3390/mi13122251 - 17 Dec 2022
Viewed by 1454
Abstract
The research on wireless communication demands technology-based efficient radio frequency devices. A printed monopole dual-band antenna is designed and presented. The presented antenna exhibits a promising response with improved bandwidth and gain. The antenna radiates from 3.49 GHz to 3.82 GHz and from [...] Read more.
The research on wireless communication demands technology-based efficient radio frequency devices. A printed monopole dual-band antenna is designed and presented. The presented antenna exhibits a promising response with improved bandwidth and gain. The antenna radiates from 3.49 GHz to 3.82 GHz and from 4.83 GHz to 5.08 GHz frequencies with 3.7 dBi and 5.26 dBi gain, having a bandwidth of 9.09% and 5.06%, respectively. The novelty in the developed antenna is that resonating elements have been engineered adequately without the use of the additional reactive component. The cost-effective FR 4 laminate is utilized as a substrate. This structure exhibits an efficiency of over 83% for both resonances. The numerically computed results through simulations and measured results are found to be in good correlation. The aforesaid response from the antenna makes it an appropriate candidate for laptop computer applications. Full article
(This article belongs to the Special Issue Advanced Antennas for Wireless Communication Systems)
►▼ Show Figures

Figure 1

14 pages, 3875 KiB  
Article
An SOI-Structured Piezoresistive Differential Pressure Sensor with High Performance
by Zebin Xu, Jiahui Yan, Meilin Ji, Yongxin Zhou, Dandan Wang, Yuanzhi Wang, Zhihong Mai, Xuefeng Zhao, Tianxiang Nan, Guozhong Xing and Songsong Zhang
Micromachines 2022, 13(12), 2250; https://doi.org/10.3390/mi13122250 - 17 Dec 2022
Cited by 4 | Viewed by 2069
Abstract
This paper presents a piezoresistive differential pressure sensor based on a silicon-on-insulator (SOI) structure for low pressure detection from 0 to 30 kPa. In the design phase, the stress distribution on the sensing membrane surface is simulated, and the doping concentration and geometry [...] Read more.
This paper presents a piezoresistive differential pressure sensor based on a silicon-on-insulator (SOI) structure for low pressure detection from 0 to 30 kPa. In the design phase, the stress distribution on the sensing membrane surface is simulated, and the doping concentration and geometry of the piezoresistor are evaluated. By optimizing the process, the realization of the pressure sensing diaphragm with a controllable thickness is achieved, and good ohmic contact is ensured. To obtain higher sensitivity and high temperature stability, an SOI structure with a 1.5 µm ultra-thin monocrystalline silicon layer is used in device manufacturing. The device diaphragm size is 700 µm × 700 µm × 2.1 µm. The experimental results show that the fabricated piezoresistive pressure sensor has a high sensitivity of 2.255 mV/V/kPa and a sensing resolution of less than 100 Pa at room temperature. The sensor has a temperature coefficient of sensitivity (TCS) of −0.221 %FS/°C and a temperature coefficient of offset (TCO) of −0.209 %FS/°C at operating temperatures ranging from 20 °C to 160 °C. The reported piezoresistive microelectromechanical systems (MEMS) pressure sensors are fabricated on 8-inch wafers using standard CMOS-compatible processes, which provides a volume solution for embedded integrated precision detection applications of air pressure, offering better insights for high-temperature and miniaturized low-pressure sensor research. Full article
(This article belongs to the Special Issue Design, Fabrication, Testing of MEMS/NEMS)
►▼ Show Figures

Figure 1

12 pages, 6494 KiB  
Article
Experimental Characterization of Laser Trepanned Microholes in Superalloy GH4220 with Water-Based Assistance
by Liang Wang, Huayu Yang, Naifei Ren, Zhengtian Wu and Kaibo Xia
Micromachines 2022, 13(12), 2249; https://doi.org/10.3390/mi13122249 - 17 Dec 2022
Cited by 1 | Viewed by 1233
Abstract
An experiment using water-assisted millisecond laser trepanning on superalloy GH4220 was carried out, and the effects of pulse energy on the hole entrance morphology, diameter, roundness, cross-section morphology, taper angle, sidewall roughness, and recast layer in air and with water-based assistance were compared [...] Read more.
An experiment using water-assisted millisecond laser trepanning on superalloy GH4220 was carried out, and the effects of pulse energy on the hole entrance morphology, diameter, roundness, cross-section morphology, taper angle, sidewall roughness, and recast layer in air and with water-based assistance were compared and analyzed. The results show that, compared with the air condition, the water-based assistance improved the material removal rate and hole quality, increased the diameter of the hole entrance and exit, increased the hole roundness, decreased the hole taper angle, decreased the hole sidewall roughness, and reduced the recast layer thickness. In addition, under the combined action of water and steam inside the hole, the sidewall surface morphology quality was improved. Compared with the air condition, the spatter around the hole entrance was reduced, but the oxidation phenomenon formed by the thermal effect surrounding the hole entrance with water-based assistance was more obvious. The research provided technical support for the industrial application of millisecond laser drilling. Full article
(This article belongs to the Special Issue Estimation and Control for Micro-Scale Cyber-Physical Systems with Applications)
►▼ Show Figures

Figure 1

7 pages, 1002 KiB  
Article
Mechanical Control of the Optical Bandgap in One-Dimensional Photonic Crystals
by V. Paige Stinson, Nuren Shuchi, Micheal McLamb, Glenn D. Boreman and Tino Hofmann
Micromachines 2022, 13(12), 2248; https://doi.org/10.3390/mi13122248 - 17 Dec 2022
Cited by 9 | Viewed by 1799
Abstract
Over the last several years, two-photon polymerization has been a popular fabrication approach for photonic crystals due to its high spatial resolution. One-dimensional photonic crystals with photonic bandgap reflectivities over 90% have been demonstrated for the infrared spectral range. With the success of [...] Read more.
Over the last several years, two-photon polymerization has been a popular fabrication approach for photonic crystals due to its high spatial resolution. One-dimensional photonic crystals with photonic bandgap reflectivities over 90% have been demonstrated for the infrared spectral range. With the success of these structures, methods which can provide tunability of the photonic bandgap are being explored. In this study, we demonstrate the use of mechanical flexures in the design of one-dimensional photonic crystals fabricated by two-photon polymerization for the first time. Experimental results show that these photonic crystals provide active mechanically induced spectral control of the photonic bandgap. An analysis of the mechanical behavior of the photonic crystal is presented and elastic behavior is observed. These results suggest that one-dimensional photonic crystals with mechanical flexures can successfully function as opto-mechanical structures. Full article
(This article belongs to the Special Issue Feature Papers of Micromachines in "Materials and Processing" 2022)
►▼ Show Figures

Figure 1

25 pages, 14056 KiB  
Article
Enhancing Performance of a MEMS-Based Piezoresistive Pressure Sensor by Groove: Investigation of Groove Design Using Finite Element Method
by Phongsakorn Thawornsathit, Ekachai Juntasaro, Hwanjit Rattanasonti, Putapon Pengpad, Karoon Saejok, Chana Leepattarapongpan, Ekalak Chaowicharat and Wutthinan Jeamsaksiri
Micromachines 2022, 13(12), 2247; https://doi.org/10.3390/mi13122247 - 17 Dec 2022
Cited by 3 | Viewed by 1986
Abstract
The optimal groove design of a MEMS piezoresistive pressure sensor for ultra-low pressure measurement is proposed in this work. Two designs of the local groove and one design of the annular groove are investigated. The sensitivity and linearity of the sensor are investigated [...] Read more.
The optimal groove design of a MEMS piezoresistive pressure sensor for ultra-low pressure measurement is proposed in this work. Two designs of the local groove and one design of the annular groove are investigated. The sensitivity and linearity of the sensor are investigated due to the variations of two dimensionless geometric parameters of these grooves. The finite element method is used to determine the stress and deflection of the diaphragm in order to find the sensor performances. The sensor performances can be enhanced by creating the annular or local groove on the diaphragm with the optimal dimensionless groove depth and length. In contrast, the performances are diminished when the local groove is created on the beam at the piezoresistor. The sensitivity can be increased by increasing the dimensionless groove length and depth. However, to maintain low nonlinearity error, the annular and local grooves should be created on the top of the diaphragm. With the optimal designs of annular and local grooves, the net volume of the annular groove is four times greater than that of the local groove. Finally, the functional forms of the stress and deflection of the diaphragm are constructed for both annular and local groove cases. Full article
(This article belongs to the Topic Micro/Nanofluidics and Structures Based Sensing, Material Processing and Energy Conversion)
►▼ Show Figures

Figure 1

26 pages, 1107 KiB  
Article
Combined Distributed Shared-Buffered and Diagonally-Linked Mesh Topology for High-Performance Interconnect
by Charles Effiong, Gilles Sassatelli and Abdoulaye Gamatié
Micromachines 2022, 13(12), 2246; https://doi.org/10.3390/mi13122246 - 17 Dec 2022
Cited by 3 | Viewed by 1915
Abstract
Networks-on-Chip (NoCs) have become the de-facto on-chip interconnect for multi/manycore systems. A typical NoC router is made up of buffers used to store packets that are unable to advance to their desired destination. However, buffers consume significant power/area and are often underutilized, especially [...] Read more.
Networks-on-Chip (NoCs) have become the de-facto on-chip interconnect for multi/manycore systems. A typical NoC router is made up of buffers used to store packets that are unable to advance to their desired destination. However, buffers consume significant power/area and are often underutilized, especially in cases of applications with non-uniform traffic patterns thus leading to performance degradation for such applications. To improve network performance, the Roundabout NoC (R-NoC) concept is considered. R-NoC is inspired by real-life multi-lane traffic roundabouts and consists of lanes that are shared by multiple input/output ports to maximize buffering resource utilization. R-NoC relies on router-internal adaptive routing that decides the lane path based on back pressure. Back pressure makes it possible to assess lane utilization and route packets accordingly. This is made possible thanks to the use of elastic buffers for control flow, a clever type of handshaking in a way similar to asynchronous circuits. Another prominent feature of R-NoC is that internal routing and arbitration are completely distributed which allows for significant freedom in deciding internal router topology and parameters. This work leverages this property and proposes novel yet unexplored configurations for which an in-depth evaluation of corresponding implementations on 45 nm CMOS technology is given. Each configuration is evaluated performance and power-wise on both synthetic and real application traffic. Several R-NoC configurations are identified and demonstrated to provide very significant performance improvements over standard mesh configurations and a typical input-buffered router, without compromising area and power consumption. Exploiting the distributed nature of R-NoC routers, a diagonally-linked configuration is then proposed which incurs moderate area overhead and features yet better performance and energy efficiency. Full article
(This article belongs to the Special Issue Network on Chip (NoC) and Reconfigurable Systems)
►▼ Show Figures

Figure 1

15 pages, 4391 KiB  
Article
Force and Velocity Analysis of Particles Manipulated by Toroidal Vortex on Optoelectrokinetic Microfluidic Platform
by Sheng-Jie Zhang, Zong-Rui Yang and Ju-Nan Kuo
Micromachines 2022, 13(12), 2245; https://doi.org/10.3390/mi13122245 - 17 Dec 2022
Viewed by 1204
Abstract
The rapid electrokinetic patterning (REP) technique has been demonstrated to enable dynamic particle manipulation in biomedical applications. Previous studies on REP have generally considered particles with a size less than 5 μm. In this study, a REP platform was used to manipulate polystyrene [...] Read more.
The rapid electrokinetic patterning (REP) technique has been demonstrated to enable dynamic particle manipulation in biomedical applications. Previous studies on REP have generally considered particles with a size less than 5 μm. In this study, a REP platform was used to manipulate polystyrene particles with a size of 3~11 μm in a microfluidic channel sandwiched between two ITO conductive glass plates. The effects of the synergy force produced by the REP electrothermal vortex on the particle motion were investigated numerically for fixed values of the laser power, AC driving voltage, and AC driving frequency, respectively. The simulation results showed that the particles were subject to a competition effect between the drag force produced by the toroidal vortex, which prompted the particles to recirculate in the bulk flow adjacent to the laser illumination spot on the lower electrode, and the trapping force produced by the particle and electrode interactions, which prompted the particles to aggregate in clusters on the surface of the illuminated spot. The experimental results showed that as the laser power increased, the toroidal flow range over which the particles circulated in the bulk flow increased, while the cluster range over which the particles were trapped on the electrode surface reduced. The results additionally showed that the particle velocity increased with an increasing laser power, particularly for particles with a smaller size. The excitation frequency at which the particles were trapped on the illuminated hot-spot reduced as the particle size increased. The force and velocity of polystyrene particles by the REP toroidal vortex has implications for further investigating the motion behavior at the biological cell level. Full article
(This article belongs to the Special Issue Recent Progress in Micropumps)
►▼ Show Figures

Figure 1

8 pages, 4689 KiB  
Article
Temperature-Independent Current Dispersion in 0.15 μm AlGaN/GaN HEMTs for 5G Applications
by Nicolò Zagni, Giovanni Verzellesi and Alessandro Chini
Micromachines 2022, 13(12), 2244; https://doi.org/10.3390/mi13122244 - 17 Dec 2022
Cited by 4 | Viewed by 1380
Abstract
Thanks to high-current densities and cutoff frequencies, short-channel length AlGaN/GaN HEMTs are a promising technology solution for implementing RF power amplifiers in 5G front-end modules. These devices, however, might suffer from current collapse due to trapping effects, leading to compressed output power. Here, [...] Read more.
Thanks to high-current densities and cutoff frequencies, short-channel length AlGaN/GaN HEMTs are a promising technology solution for implementing RF power amplifiers in 5G front-end modules. These devices, however, might suffer from current collapse due to trapping effects, leading to compressed output power. Here, we investigate the trap dynamic response in 0.15 μm GaN HEMTs by means of pulsed I-V characterization and drain current transients (DCTs). Pulsed I-V curves reveal an almost absent gate-lag but significant current collapse when pulsing both gate and drain voltages. The thermally activated Arrhenius process (with EA ≈ 0.55 eV) observed during DCT measurements after a short trap-filling pulse (i.e., 1 μs) indicates that current collapse is induced by deep trap states associated with iron (Fe) doping present in the buffer. Interestingly, analogous DCT characterization carried out after a long trap-filling pulse (i.e., 100 s) revealed yet another process with time constants of about 1–2 s and which was approximately independent of temperature. We reproduced the experimentally observed results with two-dimensional device simulations by modeling the T-independent process as the charging of the interface between the passivation and the AlGaN barrier following electron injection from the gate. Full article
(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)
►▼ Show Figures

Figure 1

15 pages, 11776 KiB  
Article
Algorithms for Weld Depth Measurement in Laser Welding of Copper with Scanning Optical Coherence Tomography
by Thomas Will, Eduardo Massieu Garcia, Claudio Hoelbling, Christian Goth and Michael Schmidt
Micromachines 2022, 13(12), 2243; https://doi.org/10.3390/mi13122243 - 16 Dec 2022
Cited by 1 | Viewed by 1609
Abstract
In-process monitoring of weld penetration depth is possible with optical coherence tomography (OCT). The weld depth can be identified with OCT by statistical signal processing of the raw OCT signal and keyhole mapping. This approach is only applicable to stable welding processes and [...] Read more.
In-process monitoring of weld penetration depth is possible with optical coherence tomography (OCT). The weld depth can be identified with OCT by statistical signal processing of the raw OCT signal and keyhole mapping. This approach is only applicable to stable welding processes and requires a time-consuming keyhole mapping to identify the optimal placement of a singular OCT measuring beam. In this work, we use an OCT measurement line for the identification of the weld depth. This approach shows the advantage that the calibration effort can be reduced as the measurement line requires only calibration in one dimension. As current literature focuses on weld depth measurement with a singular measurement point in the keyhole, no optimal algorithm exists for weld depth measurement with an OCT measurement line. We developed seven different weld depth processing pipelines and tested these algorithms under different weld conditions, such as stable deep penetration welding, unstable deep penetration welding, and heat conduction welding. We analyzed the accuracy of the weld depth processing algorithms by comparing the measured weld depth with metallographic weld depths. The intensity accumulation approach is identified as the most accurate algorithm for successful weld depth measurement with a scanning OCT measurement line. Full article
(This article belongs to the Special Issue High-Power Lasers for Materials Processing)
►▼ Show Figures

Figure 1

14 pages, 3059 KiB  
Article
A Piezoelectrically Excited ZnO Nanowire Mass Sensor with Closed-Loop Detection at Room Temperature
by Xianfa Cai and Lizhong Xu
Micromachines 2022, 13(12), 2242; https://doi.org/10.3390/mi13122242 - 16 Dec 2022
Cited by 2 | Viewed by 1286
Abstract
One-dimensional nanobeam mass sensors offer an unprecedented ability to measure tiny masses or even the mass of individual molecules or atoms, enabling many interesting applications in the fields of mass spectrometry and atomic physics. However, current nano-beam mass sensors suffer from poor real-time [...] Read more.
One-dimensional nanobeam mass sensors offer an unprecedented ability to measure tiny masses or even the mass of individual molecules or atoms, enabling many interesting applications in the fields of mass spectrometry and atomic physics. However, current nano-beam mass sensors suffer from poor real-time test performance and high environment requirements. This paper proposes a piezoelectrically excited ZnO nanowire (NW) mass sensor with closed-loop detection at room temperature to break this limitation. It is detected that the designed piezo-excited ZnO NW could operate at room temperature with a resonant frequency of 417.35 MHz, a quality factor of 3010, a mass sensitivity of −8.1 Hz/zg, and a resolution of 192 zg. The multi-field coupling dynamic model of ZnO NW mass sensor under piezoelectric excitation was established and solved. The nonlinear amplitude-frequency characteristic formula, frequency formula, modal function, sensitivity curve, and linear operating interval were obtained. The ZnO NW mass sensor was fabricated by a top-down method and its response to ethanol gas molecules was tested at room temperature. Experiments show that the sensor has high sensitivity, good closed-loop tracking performance, and high linearity, which provides great potential for the detection of biochemical reaction process of biological particles based on mechanics. Full article
(This article belongs to the Special Issue Piezoelectric Actuators and Sensors: Materials, Devices and Applications)
►▼ Show Figures

Figure 1

19 pages, 4072 KiB  
Article
Analysis of Polarization Images in the Microphysical Blood Parameters Research for the Hematocrit Diagnostics
by Ruslan D. Khlynov, Victoria A. Ryzhova, Sergey N. Yarishev, Igor A. Konyakhin, Valery V. Korotaev, Yuri E. Shelepin, Todor S. Djamiykov and Marin B. Marinov
Micromachines 2022, 13(12), 2241; https://doi.org/10.3390/mi13122241 - 16 Dec 2022
Cited by 1 | Viewed by 1119
Abstract
The development of non-invasive optoelectronic technologies for human blood monitoring is one of the important research areas for medicine. A critical analysis of optoelectronic methods of blood research and the micromechanical systems based on them is carried out in this article. A design [...] Read more.
The development of non-invasive optoelectronic technologies for human blood monitoring is one of the important research areas for medicine. A critical analysis of optoelectronic methods of blood research and the micromechanical systems based on them is carried out in this article. A design realization of a polarizing portable system for non-invasive monitoring of hematocrit as one of the basic homeostatic constants of the human body containing information about the microphysical parameters of blood cells has been substantiated. A physical model of polarized radiation conversion in a video information system of laser sensing of a biological research object has been formed. Visual and quantitative differences in the spatial distribution of polarization parameters of the scattered radiation for the states of the body with different hematocrit levels have been revealed. A scheme of a multichannel imaging portable system, based on a smartphone using miniature optical and microelectronic components of information conversion for non-invasive monitoring of microphysical blood parameters, has been created. The system implements the principle of polarimetric blood photometry and a multiparametric analysis of the polarization properties of the laser radiation scattered by blood. The developed portable optoelectronic system, based on a smartphone, can be used for rapid blood diagnostics in disaster medicine and the presence of clinical contraindications to the formation of invasive tests. The proposed polarization-based approach is a promising automated alternative to traditional devices and systems for the research of microphysical blood parameters. Full article
(This article belongs to the Special Issue Biosensors in Monitoring and Diagnosis for Medical and Agricultural Applications)
►▼ Show Figures

Graphical abstract

14 pages, 7510 KiB  
Article
Design and Development of a Triple-Band Multiple-Input–Multiple-Output Antenna for Sensing Applications
by Dinesh Kumar Raheja, Sachin Kumar, Shubhro Chakrabartty and Binod Kumar Kanaujia
Micromachines 2022, 13(12), 2240; https://doi.org/10.3390/mi13122240 - 16 Dec 2022
Cited by 1 | Viewed by 1338
Abstract
In this article, a triple-band quad-element stacked multiple-input–multiple-output (MIMO) antenna is proposed for sensing applications. Each radiating element of the presented MIMO antenna consists of a diagonally truncated square patch, which is proximity coupled to the elliptical radiating patch. The proposed MIMO antenna [...] Read more.
In this article, a triple-band quad-element stacked multiple-input–multiple-output (MIMO) antenna is proposed for sensing applications. Each radiating element of the presented MIMO antenna consists of a diagonally truncated square patch, which is proximity coupled to the elliptical radiating patch. The proposed MIMO antenna is designed to resonate for three frequencies (4.2, 4.8, and 5.8 GHz) in the C-band range. The antenna shows circular polarization characteristics at 4.2 and 4.8 GHz frequencies. Each stacked element of the proposed antenna is excited independently through a 50 Ω coaxial feed. The Rogers RT Duroid/5880 dielectric substrate is used for the fabrication of two layers of the stacked MIMO antenna. The presented stacked MIMO antenna simulation and experimental outcomes are in good agreement. Full article
(This article belongs to the Special Issue RFID Sensors for Environmental, Agri-Food and Industrial Applications)
►▼ Show Figures

Figure 1

25 pages, 3518 KiB  
Review
Environmental, Economic, and Social Aspects of Human Urine Valorization through Microbial Fuel Cells from the Circular Economy Perspective
by Mariana Martínez-Castrejón, Jazmin A. López-Díaz, Omar Solorza-Feria, Oscar Talavera-Mendoza, América L. Rodríguez-Herrera, Osbelia Alcaraz-Morales and Giovanni Hernández-Flores
Micromachines 2022, 13(12), 2239; https://doi.org/10.3390/mi13122239 - 16 Dec 2022
Cited by 3 | Viewed by 2146
Abstract
Population growth increases the challenge of meeting basic human needs, such as water, a limited resource. Consumption habits and water pollution have compromised natural resources to unsustainable levels. Sustainable effluent treatment practices, such as decentralized systems focused on energy, nutrients, and water recovery, [...] Read more.
Population growth increases the challenge of meeting basic human needs, such as water, a limited resource. Consumption habits and water pollution have compromised natural resources to unsustainable levels. Sustainable effluent treatment practices, such as decentralized systems focused on energy, nutrients, and water recovery, have attracted the attention of the scientific community. Human urine (HU) is a physiological liquid waste whose main component is water (~95%). HU has a significant amount of nutrients, such as N, P, K, and organic matter, which are usually lacking in fecal coliforms. Therefore, the possibility exists of recovering nutrients and energy from HU using sustainable and non-sustainable technologies. Treating HU in bioelectrochemical systems (BES) is a novel alternative to obtaining byproducts from this effluent more sustainably than in electrochemical systems. Microbial fuel cells (MFCs) are an interesting example, contributing to HU revalorization from unwanted waste into a valuable resource of nutrients, energy, and water. Even when urine-operated MFCs have not generated attractive potential outputs or produced considerable amounts of bioelectricity, this review emphasizes HU advantages as nutrients or water sources. The aim of this review was to analyze the current development of BES for HU treatment based on the water circular economy, discussing challenges and perspectives researchers might encounter. Full article
(This article belongs to the Special Issue Sustainable Materials for Energy and Environmental Applications)
►▼ Show Figures

Graphical abstract

13 pages, 3651 KiB  
Article
A Rapid and Simple Method for Purification of Nucleic Acids on Porous Membranes: Simulation vs. Experiment
by Angela Fonseca-Benitez, Consuelo Romero-Sánchez and Sandra Janneth Perdomo Lara
Micromachines 2022, 13(12), 2238; https://doi.org/10.3390/mi13122238 - 16 Dec 2022
Cited by 2 | Viewed by 1590
Abstract
Paper-based microfluidic systems have emerged as one of the most promising technologies for developing point-of-care diagnostic platforms (POCT) for detecting and monitoring various diseases. Saliva is a non-invasive biofluid easily collected, transported, and stored. Due to its accessibility and connection to systemic diseases, [...] Read more.
Paper-based microfluidic systems have emerged as one of the most promising technologies for developing point-of-care diagnostic platforms (POCT) for detecting and monitoring various diseases. Saliva is a non-invasive biofluid easily collected, transported, and stored. Due to its accessibility and connection to systemic diseases, saliva is one of the best candidates for medical advancement at the point of care, where people can easily monitor their health. However, saliva is a complex mixture of DNA, RNA, proteins, exosomes, and electrolytes. Thus, nucleic acid separation from the salivary components is essential for PCR applications. Paper membranes are a highly porous and foldable structure capable of transporting fluids without pumps and sophisticated systems. The current work presents an insight into simulations for nucleic acid extraction on three types of porous paper membranes for use in point-of-care devices. The flow fluid model is solved on a COMSOL Multiphysics 5.3 free version platform, and the results are compared with experimental assays. The results show that pore uniformity, wet strength, porosity, and functional groups of MF1™ and Fusion 5™ paper membranes are vital parameters affecting nucleic acid extraction and PCR amplification efficiency. Full article
(This article belongs to the Special Issue Microfluidic Cell Assay Chips, Volume II)
►▼ Show Figures

Figure 1

17 pages, 4095 KiB  
Article
A Deep-Learning-Based Guidewire Compliant Control Method for the Endovascular Surgery Robot
by Chuqiao Lyu, Shuxiang Guo, Wei Zhou, Yonggan Yan, Chenguang Yang, Yue Wang and Fanxu Meng
Micromachines 2022, 13(12), 2237; https://doi.org/10.3390/mi13122237 - 16 Dec 2022
Cited by 6 | Viewed by 1889
Abstract
Endovascular surgery is a high-risk operation with limited vision and intractable guidewires. At present, endovascular surgery robot (ESR) systems based on force feedback liberates surgeons’ operation skills, but it lacks the ability to combine force perception with vision. In this study, a deep [...] Read more.
Endovascular surgery is a high-risk operation with limited vision and intractable guidewires. At present, endovascular surgery robot (ESR) systems based on force feedback liberates surgeons’ operation skills, but it lacks the ability to combine force perception with vision. In this study, a deep learning-based guidewire-compliant control method (GCCM) is proposed, which guides the robot to avoid surgical risks and improve the efficiency of guidewire operation. First, a deep learning-based model called GCCM-net is built to identify whether the guidewire tip collides with the vascular wall in real time. The experimental results in a vascular phantom show that the best accuracy of GCCM-net is 94.86 ± 0.31%. Second, a real-time operational risk classification method named GCCM-strategy is proposed. When the surgical risks occur, the GCCM-strategy uses the result of GCCM-net as damping and decreases the robot’s running speed through virtual resistance. Compared with force sensors, the robot with GCCM-strategy can alleviate the problem of force position asynchrony caused by the long and soft guidewires in real-time. Experiments run by five guidewire operators show that the GCCM-strategy can reduce the average operating force by 44.0% and shorten the average operating time by 24.6%; therefore the combination of vision and force based on deep learning plays a positive role in improving the operation efficiency in ESR. Full article
(This article belongs to the Special Issue Assistive Robots)
►▼ Show Figures

Figure 1

13 pages, 2497 KiB  
Article
Vibration-Assisted Synthesis of Nanoporous Anodic Aluminum Oxide (AAO) Membranes
by Urte Cigane, Arvydas Palevicius and Giedrius Janusas
Micromachines 2022, 13(12), 2236; https://doi.org/10.3390/mi13122236 - 16 Dec 2022
Cited by 2 | Viewed by 1169
Abstract
In recent years, many research achievements in the field of anodic aluminum oxide (AAO) membranes can be observed. Nevertheless, it is still an interesting research topic due to its high versatility and applications in various fields, such as template-assisted methods, filtration, sensors, etc. [...] Read more.
In recent years, many research achievements in the field of anodic aluminum oxide (AAO) membranes can be observed. Nevertheless, it is still an interesting research topic due to its high versatility and applications in various fields, such as template-assisted methods, filtration, sensors, etc. Nowadays, miniaturization is an integral part of different technologies; therefore, research on micro- and nanosized elements is relevant in areas such as LEDs and OLEDs, solar cells, etc. To achieve an efficient mixing process of fluid flow in straight nanopores, acoustofluidic physics has attracted great interest in recent decades. Unfortunately, the renewal of the electrolyte concentration at the bottom of a pore is limited. Thus, excitation is used to improve fluid mixing along nanosized diameters. The effect of excitation by high-frequency vibrations on pore geometry is also investigated. In this study, theoretical simulations were performed. Using theoretical calculations, the acoustic pressure, acoustic velocity, and velocity magnitude were obtained at frequencies of 2, 20, and 40 kHz. Moreover, nanoporous AAO membranes were synthesized, and the influence of high-frequency vibrations on the geometry of the pores was determined. Using a high-frequency excitation of 20 kHz, the thickness of the AAO membrane increased by 17.8%. In addition, the thickness increased by 31.1% at 40 kHz and 33.3% at the resonant frequency of 40 kHz. Using high-frequency vibrations during the anodization process, the electrolyte inside the pores is mixed, and as a result, a higher oxide growth rate and a deeper structure can be achieved. On the other hand, to obtain pores of the same depth, the reaction can be performed in a shorter time. Full article
(This article belongs to the Special Issue Advance in Energy Conversion and Storage: Material, Design and Application)
►▼ Show Figures

Figure 1

13 pages, 2580 KiB  
Article
A Novel Cortisol Immunosensor Based on a Hafnium Oxide/Silicon Structure for Heart Failure Diagnosis
by Hamdi Ben Halima, Nadia Zine, Joan Bausells, Nicole Jaffrezic-Renault and Abdelhamid Errachid
Micromachines 2022, 13(12), 2235; https://doi.org/10.3390/mi13122235 - 16 Dec 2022
Cited by 3 | Viewed by 1363
Abstract
Assessing cortisol levels in human bodies has become essential to diagnose heart failure (HF). In this work, we propose a salivary cortisol detection strategy as part of an easily integrable lab-on-a-chip for detection of HF biomarkers. Our developed capacitive immunosensor based on hafnium [...] Read more.
Assessing cortisol levels in human bodies has become essential to diagnose heart failure (HF). In this work, we propose a salivary cortisol detection strategy as part of an easily integrable lab-on-a-chip for detection of HF biomarkers. Our developed capacitive immunosensor based on hafnium oxide (HfO2)/silicon structure showed good linearity between increasing cortisol concentration and the charge-transfer resistance/capacitance. Moreover, the developed biosensor was demonstrated to be highly selective toward cortisol compared to other HF biomarkers such as tumor necrosis factor (TNF-α) and N-terminal pro-brain natriuretic peptide (NT-proBNP). The precision of our developed biosensor was evaluated, and the difference between the determined cortisol concentration in saliva and its expected one is <18%. Full article
(This article belongs to the Special Issue Biosensors for Diagnostic and Detection Applications)
►▼ Show Figures

Figure 1

9 pages, 2735 KiB  
Article
Flower-Shaped CoS-Co2O3/G-C3N4 Nanocomposite for Two-Symmetric-Electrodes Supercapacitor of High Capacitance Efficiency Examined in Basic and Acidic Mediums
by Mohamed Rabia, Doaa Essam, Fatemah H. Alkallas, Mohamed Shaban, Samira Elaissi and Amira Ben Gouider Trabelsi
Micromachines 2022, 13(12), 2234; https://doi.org/10.3390/mi13122234 - 16 Dec 2022
Cited by 21 | Viewed by 1777
Abstract
Graphitic carbon nitride (G-C3N4) was synthesized through the direct combustion of urea in the air. The CoS-Co2O3/G-C3N4 composite was synthesized via the hydrothermal method of G-C3N4 using cobalt salts. The morphological and chemical structures were determined through XRD, XPS, [...] Read more.
Graphitic carbon nitride (G-C3N4) was synthesized through the direct combustion of urea in the air. The CoS-Co2O3/G-C3N4 composite was synthesized via the hydrothermal method of G-C3N4 using cobalt salts. The morphological and chemical structures were determined through XRD, XPS, SEM, and TEM. XRD and XPS analyses confirmed the chemical structure, function groups, and elements percentage of the prepared nanocomposite. SEM measurements illustrated the formation of G-C3N4 sheets, as well as the flower shape of the CoS-Co2O3/G-C3N4 composite, evidenced through the formation of nano appendages over G-C3N4 sheets. TEM confirmed the 2D nanosheets of G-C3N4 with an average width and length of 80 nm and 170 nm, respectively. Two symmetric electrodes for the supercapacitor from the CoS-Co2O3/G-C3N4 composite. Electrochemical measurements were carried out to determine the charge/discharge, cyclic voltammetry, stability, and impedance of the prepared supercapacitor. The measurements were carried out under acid (0.5 M HCL) and basic (6.0 M NaOH) mediums. The charge and discharge lifetime values in the acid and base medium were 85 and 456 s, respectively. The cyclic voltammetry behavior was rectangular in a base medium for the pseudocapacitance feature. The supercapacitor had 100% stability retention up to 600 cycles; then, the stability decreased to 98.5% after 1000 cycles. The supercapacitor displayed a specific capacitance (CS) of 361 and 92 F/g, and an energy density equal to 28.7 and 30.2 W h kg−1 in the basic and acidic mediums, respectively. Our findings demonstrate the capabilities of supercapacitors to become an alternative solution to batteries, owing to their easy and low-cost manufacturing technique. Full article
(This article belongs to the Special Issue Graphene-Nanocomposite-Based Flexible Supercapacitors)
►▼ Show Figures

Figure 1

10 pages, 2522 KiB  
Article
Time-Modulated Antenna Arrays for Ultra-Wideband 5G Applications
by Gonzalo Maldonado, Alberto Reyna Maldonado, Luz I. Balderas and Marco A. Panduro
Micromachines 2022, 13(12), 2233; https://doi.org/10.3390/mi13122233 - 16 Dec 2022
Cited by 1 | Viewed by 1715
Abstract
This research presents the design of time-modulated antenna arrays with UWB performance. The antenna arrays consider a linear topology with eight UWB disk-notch patch antennas. The technological problem is to find out the optimum antenna positions and/or time sequences to reduce the side [...] Read more.
This research presents the design of time-modulated antenna arrays with UWB performance. The antenna arrays consider a linear topology with eight UWB disk-notch patch antennas. The technological problem is to find out the optimum antenna positions and/or time sequences to reduce the side lobes and the sidebands in all of the UWB frequency ranges. The design process is formulated as a bacterial foraging optimization. The results show that the uniform array generates a better SLL performance whereas the non-uniform array obtains a wider bandwidth. The uniform array obtains an SLL < −20 dB from 3.37 GHz to 4.8 GHz and the non-uniform array generates an SLL < −7 dB from 2.97 GHz to 5.26 GHz. The sideband levels are very similar for both cases with a value of around −17 dB. Full article
(This article belongs to the Special Issue Microwave Antennas: From Fundamental Research to Applications)
►▼ Show Figures

Figure 1

11 pages, 3886 KiB  
Article
A Nitrocellulose Paper-Based Multi-Well Plate for Point-of-Care ELISA
by Zhen Qin, Zongjie Huang, Peng Pan, Yueyue Pan, Runze Zuo, Yu Sun and Xinyu Liu
Micromachines 2022, 13(12), 2232; https://doi.org/10.3390/mi13122232 - 16 Dec 2022
Cited by 6 | Viewed by 2448
Abstract
Low-cost diagnostic tools for point-of-care immunoassays, such as the paper-based enzyme-linked immunoassay (ELISA), have become increasingly important, especially so in the recent COVID-19 pandemic. ELISA is the gold-standard antibody/antigen sensing method. This paper reports an easy-to-fabricate nitrocellulose (NC) paper plate, coupled with a [...] Read more.
Low-cost diagnostic tools for point-of-care immunoassays, such as the paper-based enzyme-linked immunoassay (ELISA), have become increasingly important, especially so in the recent COVID-19 pandemic. ELISA is the gold-standard antibody/antigen sensing method. This paper reports an easy-to-fabricate nitrocellulose (NC) paper plate, coupled with a desktop scanner for ELISA, which provides a higher protein immobilization efficiency than the conventional cellulose paper-based ELISA platforms. The experiments were performed using spiked samples for the direct ELISA of rabbit IgG with a limit of detection (LOD) of 1.016 μg/mL, in a measurement range of 10 ng/mL to 1 mg/mL, and for the sandwich ELISA of sperm protein (SP-10) with an LOD of 88.8 ng/mL, in a measurement range of 1 ng/mL to 100 μg/mL. The described fabrication method, based on laser-cutting, is a highly flexible one-step laser micromachining process, which enables the rapid production of low-cost NC paper-based multi-well plates with different sizes for the ELISA measurements. Full article
(This article belongs to the Topic Advances in Microfluidics and Lab on a Chip Technology)
►▼ Show Figures

Figure 1

15 pages, 6312 KiB  
Article
Predicting the Optimal Input Parameters for the Desired Print Quality Using Machine Learning
by Rajalakshmi Ratnavel, Shreya Viswanath, Jeyanthi Subramanian, Vinoth Kumar Selvaraj, Valarmathi Prahasam and Sanjay Siddharth
Micromachines 2022, 13(12), 2231; https://doi.org/10.3390/mi13122231 - 16 Dec 2022
Cited by 2 | Viewed by 1822
Abstract
3D printing is a growing technology being incorporated into almost every industry. Although it has obvious advantages, such as precision and less fabrication time, it has many shortcomings. Although several attempts were made to monitor the errors, many have not been able to [...] Read more.
3D printing is a growing technology being incorporated into almost every industry. Although it has obvious advantages, such as precision and less fabrication time, it has many shortcomings. Although several attempts were made to monitor the errors, many have not been able to thoroughly address them, like stringing, over-extrusion, layer shifting, and overheating. This paper proposes a study using machine learning to identify the optimal process parameters such as infill structure and density, material (ABS, PLA, Nylon, PVA, and PETG), wall and layer thickness, count, and temperature. The result thus obtained was used to train a machine learning algorithm. Four different network architectures (CNN, Resnet152, MobileNet, and Inception V3) were used to build the algorithm. The algorithm was able to predict the parameters for a given requirement. It was also able to detect any errors. The algorithm was trained to pause the print immediately in case of a mistake. Upon comparison, it was found that the algorithm built with Inception V3 achieved the best accuracy of 97%. The applications include saving the material from being wasted due to print time errors in the manufacturing industry. Full article
(This article belongs to the Special Issue Machine Learning for Advanced Manufacturing)
►▼ Show Figures

Figure 1

Show export options expand_more Show export options expand_less
Select all
Export citation of selected articles as:
 
Displaying articles 1-224
Previous Issue
Next Issue
Back to TopTop