Micromachines

18 pages, 29355 KiB

Open AccessArticle

Three-Dimensionally Printed Self-Lock Origami: Design, Fabrication, and Simulation to Improve Performance of Rotational Joint

by Samira Zare, Alex Spaeth, Sandya Suresh and Mircea Teodorescu

Micromachines 2023, 14(8), 1649; https://doi.org/10.3390/mi14081649 - 21 Aug 2023

Cited by 1 | Viewed by 1323

Abstract

Origami structures have made significant contributions to the field of robotics, offering various advantages. One such advantage is their ability to conserve space by transforming the structure into a compact form. Additionally, many origami structures can be fabricated in a flat state to [...] Read more.

Origami structures have made significant contributions to the field of robotics, offering various advantages. One such advantage is their ability to conserve space by transforming the structure into a compact form. Additionally, many origami structures can be fabricated in a flat state to simplify manufacturing, giving them the potential for large-scale and cost-effective production. Rotational joints play a crucial role in the construction of robotic systems, yet origami rotational joints can suffer from a limited range of motion. We previously theoretically proposed the Self-Lock Joint to address this issue, but it is only partially flat-foldable. This paper presents a novel approach to the 3D printing of modular origami joints, such as the Self-Lock Joint, using 3D-printed plates joined with a fabric layer. The compliance of the fabric can improve the joint’s semi flat-foldability or even enable it to achieve complete flat-foldability. Furthermore, the rotational motion of the joint is enhanced, allowing for close to 360 degrees of rotational movement. We assess the physical properties of the joint under both loaded and unloaded conditions in order to identify design trade-offs in the physical properties of the joints. Moreover, as a proof of concept, we construct and demonstrate manipulators utilizing these joints. The increase in rotational movement enabled by this fabrication method, coupled with the compliant joint’s flat-foldability and modular nature, make it a promising candidate for use in a wide range of applications. Full article

(This article belongs to the Special Issue Origami Devices: Design and Application)

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19 pages, 1821 KiB

Open AccessReview

Application of 3D Bioprinting in Liver Diseases

by Wenhui Li, Zhaoyue Liu, Fengwei Tang, Hao Jiang, Zhengyuan Zhou, Xiuqing Hao and Jia Ming Zhang

Micromachines 2023, 14(8), 1648; https://doi.org/10.3390/mi14081648 - 21 Aug 2023

Cited by 4 | Viewed by 2600

Abstract

Liver diseases are the primary reason for morbidity and mortality in the world. Owing to a shortage of organ donors and postoperative immune rejection, patients routinely suffer from liver failure. Unlike 2D cell models, animal models, and organoids, 3D bioprinting can be successfully [...] Read more.

Liver diseases are the primary reason for morbidity and mortality in the world. Owing to a shortage of organ donors and postoperative immune rejection, patients routinely suffer from liver failure. Unlike 2D cell models, animal models, and organoids, 3D bioprinting can be successfully employed to print living tissues and organs that contain blood vessels, bone, and kidney, heart, and liver tissues and so on. 3D bioprinting is mainly classified into four types: inkjet 3D bioprinting, extrusion-based 3D bioprinting, laser-assisted bioprinting (LAB), and vat photopolymerization. Bioinks for 3D bioprinting are composed of hydrogels and cells. For liver 3D bioprinting, hepatic parenchymal cells (hepatocytes) and liver nonparenchymal cells (hepatic stellate cells, hepatic sinusoidal endothelial cells, and Kupffer cells) are commonly used. Compared to conventional scaffold-based approaches, marked by limited functionality and complexity, 3D bioprinting can achieve accurate cell settlement, a high resolution, and more efficient usage of biomaterials, better mimicking the complex microstructures of native tissues. This method will make contributions to disease modeling, drug discovery, and even regenerative medicine. However, the limitations and challenges of this method cannot be ignored. Limitation include the requirement of diverse fabrication technologies, observation of drug dynamic response under perfusion culture, the resolution to reproduce complex hepatic microenvironment, and so on. Despite this, 3D bioprinting is still a promising and innovative biofabrication strategy for the creation of artificial multi-cellular tissues/organs. Full article

(This article belongs to the Special Issue Micro- and Nanoscale Science, Technology and Engineering in Nanjing University of Aeronautics and Astronautics: Celebrating 70th Anniversary)

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12 pages, 3648 KiB

Open AccessArticle

Surface Characteristics Affect the Properties of PLGA Nanoparticles as Photothermal Agents

by Vera L. Kovalenko, Olga A. Kolesnikova, Maxim P. Nikitin, Victoria O. Shipunova and Elena N. Komedchikova

Micromachines 2023, 14(8), 1647; https://doi.org/10.3390/mi14081647 - 21 Aug 2023

Viewed by 1131

Abstract

Photothermal therapy is one of the most promising and rapidly developing fields in modern oncology due to its high efficiency, localized action, and minimal invasiveness. Polymeric nanoparticles (NPs) incorporating low molecular-weight photothermal dyes are capable of delivering therapeutic agents to the tumor site, [...] Read more.

Photothermal therapy is one of the most promising and rapidly developing fields in modern oncology due to its high efficiency, localized action, and minimal invasiveness. Polymeric nanoparticles (NPs) incorporating low molecular-weight photothermal dyes are capable of delivering therapeutic agents to the tumor site, releasing them in a controlled manner, and providing tumor treatment under external light irradiation. The nanoparticle synthesis components are critically important factors that influence the therapeutically significant characteristics of polymeric NPs. Here, we show the impact of stabilizers and solvents used for synthesis on the properties of PLGA NPs for photothermal therapy. We synthesized PLGA nanocarriers using the microemulsion method and varied the nature of the solvent and the concentration of the stabilizer—namely, chitosan oligosaccharide lactate. A phthalocyanine-based photosensitizer, which absorbs light in the NIR window, was encapsulated in the PLGA NPs. When mQ water was used as a solvent and chitosan oligosaccharide lactate was used at a concentration of 1 g/L, the PLGA NPs exhibited highly promising photothermal properties. The final composite of the nanocarriers demonstrated photoinduced cytotoxicity against EMT6/P cells under NIR laser irradiation in vitro and was suitable for bioimaging. Full article

(This article belongs to the Section B3: Nanoparticles in Biomedicine)

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13 pages, 2902 KiB

Open AccessArticle

Customised Implant for Temporomandibular Joint: New Technique to Design and Stress Analysis to Balance the Loading at Both Ends

by Anubhav Tiwari, Ishfaq A. Ahmed, Vijay Kumar Gupta, Rakesh Kumar Haldkar and Ivan A. Parinov

Micromachines 2023, 14(8), 1646; https://doi.org/10.3390/mi14081646 - 20 Aug 2023

Cited by 1 | Viewed by 1173

Abstract

The temporomandibular joint (TMJ) is a critical joint for the opening and closing of the mouth. The generation of customised TMJs according to individuals’ dental anatomy is needed. Currently, the implants available on the market lack consideration of the patient’s dental anatomy. This [...] Read more.

The temporomandibular joint (TMJ) is a critical joint for the opening and closing of the mouth. The generation of customised TMJs according to individuals’ dental anatomy is needed. Currently, the implants available on the market lack consideration of the patient’s dental anatomy. This leads to the creation of an imbalance in the reaction forces on both ends of the TMJ. This requires a slight structural change in the design parameters to give a solution. The purpose of this study is to propose a new design that includes the geometry and materials for a TMJ implant. Stress analysis was carried out on the TMJ to balance the reaction forces at both TMJ ends. A static analysis was performed using ANSYS Workbench, to compare the results of two customised designs of TMJ implants, in order to better balance the reaction forces at both ends. The model in the study showed that the reaction forces for both the patient-specific TMJ implants were nearly balanced. The reaction forces were better balanced, and almost equivalent to the intact conditions. The stresses in the mandible were more uniformly distributed in the customised design of the TMJ implant. The two types of design showed that the custom design took up less space in the patient’s region of surgery, making it a better option compared to a stock TMJ implant. The custom implant would allow faster patient rehabilitation, as the reaction forces would be close to those in intact conditions. Full article

(This article belongs to the Special Issue Structural Analyses and Designs for Flexible/Stretchable Electronics, Volume II)

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18 pages, 8379 KiB

Open AccessArticle

Investigation of a Novel Ultra-Low-Frequency Rotational Energy Harvester Based on a Double-Frequency Up-Conversion Mechanism

by Ning Li, Hu Xia, Chun Yang, Tao Luo and Lifeng Qin

Micromachines 2023, 14(8), 1645; https://doi.org/10.3390/mi14081645 - 20 Aug 2023

Viewed by 1320

Abstract

Due to their lack of pollution and long replacement cycles, piezoelectric energy harvesters have gained increasing attention as emerging power generation devices. However, achieving effective energy harvesting in ultra-low-frequency (<1 Hz) rotational environments remains a challenge. Therefore, a novel rotational energy harvester (REH) [...] Read more.

Due to their lack of pollution and long replacement cycles, piezoelectric energy harvesters have gained increasing attention as emerging power generation devices. However, achieving effective energy harvesting in ultra-low-frequency (<1 Hz) rotational environments remains a challenge. Therefore, a novel rotational energy harvester (REH) with a double-frequency up-conversion mechanism was proposed in this study. It consisted of a hollow cylindrical shell with multiple piezoelectric beams and a ring-shaped slider with multiple paddles. During operation, the relative rotation between the slider and the shell induced the paddles on the slider to strike the piezoelectric beams inside the shell, thereby causing the piezoelectric beams to undergo self-excited oscillation and converting mechanical energy into electrical energy through the piezoelectric effect. Additionally, by adjusting the number of paddles and piezoelectric beams, the frequency of the piezoelectric beam struck by the paddles within one rotation cycle could be increased, further enhancing the output performance of the REH. To validate the output performance of the proposed REH, a prototype was fabricated, and the relationship between the device’s output performance and parameters such as the number of paddles, system rotation speed, and device installation eccentricity was studied. The results showed that the designed REH achieved a single piezoelectric beam output power of up to 2.268 mW, while the REH with three piezoelectric beams reached an output power of 5.392 mW, with a high power density of 4.02 μW/(cm³ Hz) under a rotational excitation of 0.42 Hz, demonstrating excellent energy-harvesting characteristics. Full article

(This article belongs to the Special Issue Energy Harvesters and Self-Powered Sensors for Smart Electronics, 2nd Edition)

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18 pages, 7426 KiB

Open AccessArticle

Towards High Capacitive Performance of Chemically Deposited β-Ni(OH)₂ Nanolamellae Electrode Films

by Kevin Radakishna Moonooswamy and Mohammed Es-Souni

Micromachines 2023, 14(8), 1644; https://doi.org/10.3390/mi14081644 - 20 Aug 2023

Viewed by 820

Abstract

Nickel hydroxide β-Ni(OH)₂ nanolamellae with high aspect ratios were grown via chemical bath deposition (CBD) on both smooth and textured nickel foil. Depending on bath composition and/or the presence of an additive, thin foam-like nanolamellae to stacked lamellae were obtained. The used [...] Read more.

Nickel hydroxide β-Ni(OH)₂ nanolamellae with high aspect ratios were grown via chemical bath deposition (CBD) on both smooth and textured nickel foil. Depending on bath composition and/or the presence of an additive, thin foam-like nanolamellae to stacked lamellae were obtained. The used CBD method is highly cost-effective, as it is faster and requires less chemicals than typical hydrothermal methods, and it is readily implementable for large-scale production. The influence of surface texture on the final morphology and its effect on capacitive performance was investigated. Herein, we show how subtle changes in the concentration can drastically influence the morphology, which, in turn, drastically impacts the supercapacitive performance of the electrode. Also, the use of a textured surface significantly impacts the morphology, with vastly better cycling performance than samples made on a relatively smooth substrate. The measured specific capacitance values of the best sample were 1961 Fg⁻¹ at 5 mVs⁻¹ and 1998 Fg⁻¹ at 1 Ag⁻¹ under potentiostatic and galvanostatic conditions, respectively. This sample also retained 100% of its initial specific capacitance when discharged at a very high current density of 40 Ag⁻¹. These values are substantially enhanced compared to previously reported data using a nearly analogous method (CBD with higher reagent conc.), with our method, cost-wise, offering economic advantages relative to results obtained with similar materials and other methods (e.g., hydrothermal). Full article

(This article belongs to the Special Issue Nanostructures for Application in Electronics and Renewable Energy Sources)

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27 pages, 11327 KiB

Open AccessReview

Biohybrid Soft Robots Powered by Myocyte: Current Progress and Future Perspectives

by Zheng Yuan, Qinghao Guo, Delu Jin, Peifan Zhang and Wenguang Yang

Micromachines 2023, 14(8), 1643; https://doi.org/10.3390/mi14081643 - 20 Aug 2023

Cited by 1 | Viewed by 1582

Abstract

Myocyte-driven robots, a type of biological actuator that combines myocytes with abiotic systems, have gained significant attention due to their high energy efficiency, sensitivity, biocompatibility, and self-healing capabilities. These robots have a unique advantage in simulating the structure and function of human tissues [...] Read more.

Myocyte-driven robots, a type of biological actuator that combines myocytes with abiotic systems, have gained significant attention due to their high energy efficiency, sensitivity, biocompatibility, and self-healing capabilities. These robots have a unique advantage in simulating the structure and function of human tissues and organs. This review covers the research progress in this field, detailing the benefits of myocyte-driven robots over traditional methods, the materials used in their fabrication (including myocytes and extracellular materials), and their properties and manufacturing techniques. Additionally, the review explores various control methods, robot structures, and motion types. Lastly, the potential applications and key challenges faced by myocyte-driven robots are discussed and summarized. Full article

(This article belongs to the Special Issue Fusing Biology and Engineering: Manufacturing, Applications, and Future Trends in Bio-Hybrid Systems)

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20 pages, 3819 KiB

Open AccessArticle

Optimising Surface Roughness and Density in Titanium Fabrication via Laser Powder Bed Fusion

by Hany Hassanin, Mahmoud Ahmed El-Sayed, Mahmoud Ahmadein, Naser A. Alsaleh, Sabbah Ataya, Mohamed M. Z. Ahmed and Khamis Essa

Micromachines 2023, 14(8), 1642; https://doi.org/10.3390/mi14081642 - 20 Aug 2023

Cited by 1 | Viewed by 1220

Abstract

The Ti6Al4V alloy has many advantages, such as being lightweight, formal, and resistant to corrosion. This makes it highly desirable for various applications, especially in the aerospace industry. Laser Powder Bed Fusion (LPBF) is a technique that allows for the production of detailed [...] Read more.

The Ti6Al4V alloy has many advantages, such as being lightweight, formal, and resistant to corrosion. This makes it highly desirable for various applications, especially in the aerospace industry. Laser Powder Bed Fusion (LPBF) is a technique that allows for the production of detailed and unique parts with great flexibility in design. However, there are challenges when it comes to achieving high-quality surfaces and porosity formation in the material, which limits the wider use of LPBF. To tackle these challenges, this study uses statistical techniques called Design of Experiments (DoE) and Analysis of Variance (ANOVA) to investigate and optimise the process parameters of LPBF for making Ti6Al4V components with improved density and surface finish. The parameters examined in this study are laser power, laser scan speed, and hatch space. The optimisation study results show that using specific laser settings, like a laser power of 175 W, a laser scan speed of 1914 mm/s, and a hatch space of 53 µm, produces Ti6Al4V parts with a high relative density of 99.54% and low top and side surface roughness of 2.6 µm and 4.3 µm, respectively. This promising outcome demonstrates the practicality of optimising Ti6Al4V and other metal materials for a wide range of applications, thereby overcoming existing limitations and further expanding the potential of LPBF while minimising inherent process issues. Full article

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

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27 pages, 5555 KiB

Open AccessArticle

A Frequency-Dependent Dynamic Electric–Mechanical Network for Thin-Wafer Piezoelectric Transducers Polarized in the Thickness Direction: Physical Model and Experimental Confirmation

by Lin Fa, Dongning Liu, Hong Gong, Wenhui Chen, Yandong Zhang, Yimei Wang, Rui Liang, Baoni Wang, Guiquan Shi, Xiangrong Fang, Yuxia Li and Meishan Zhao

Micromachines 2023, 14(8), 1641; https://doi.org/10.3390/mi14081641 - 20 Aug 2023

Viewed by 771

Abstract

This paper is concerned with electric–acoustic/acoustic–electric conversions of thin-wafer piezoelectric transducers polarized in the thickness direction. By introducing two mechanical components with frequency-dependent values, i.e., radiation resistance and radiation mass, into the equivalent circuit of the thin-wafer piezoelectric transducer, we established a frequency-dependent [...] Read more.

This paper is concerned with electric–acoustic/acoustic–electric conversions of thin-wafer piezoelectric transducers polarized in the thickness direction. By introducing two mechanical components with frequency-dependent values, i.e., radiation resistance and radiation mass, into the equivalent circuit of the thin-wafer piezoelectric transducer, we established a frequency-dependent dynamic mechanic-electric equivalent network with four terminals for an arbitrary given frequency, an enhancement from the conventional circuit networks. We derived the analytic expressions of its electric–acoustic and acoustic–electric conversion impulse responses using the four-terminal equivalent circuit to replace the traditional six-terminal equivalent circuit for a thin-wafer transducer with harmonic vibrational motion. For multifrequency electrical/acoustic signals acting on the transducer, we established parallel electric–acoustic/acoustic–electric conversion transmission networks. These two transmission network models have simple structures and clear physical and mathematical descriptions of thin-wafer transducers for electric–acoustic/acoustic–electric conversion when excited by a multifrequency electric/acoustic signal wavelet. The calculated results showed that the transducer’s center frequency shift relates to its mechanical load and vibration state. The method reported in this paper can be applied to conventional-sized and small-sized piezoelectric transducers with universal applicability. Full article

(This article belongs to the Special Issue Piezoelectric Actuators and Sensors: Materials, Devices and Applications)

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18 pages, 3642 KiB

Open AccessReview

Multilayered Functional Triboelectric Polymers for Self-Powered Wearable Applications: A Review

by Minsoo P. Kim

Micromachines 2023, 14(8), 1640; https://doi.org/10.3390/mi14081640 - 20 Aug 2023

Cited by 1 | Viewed by 1222

Abstract

Multifunctional wearable devices detect electric signals responsive to various biological stimuli and monitor present body motions or conditions, necessitating flexible materials with high sensitivity and sustainable operation. Although various dielectric polymers have been utilized in self-powered wearable applications in response to multiple external [...] Read more.

Multifunctional wearable devices detect electric signals responsive to various biological stimuli and monitor present body motions or conditions, necessitating flexible materials with high sensitivity and sustainable operation. Although various dielectric polymers have been utilized in self-powered wearable applications in response to multiple external stimuli, their intrinsic limitations hinder further device performance enhancement. Because triboelectric devices comprising dielectric polymers are based on triboelectrification and electrostatic induction, multilayer-stacking structures of dielectric polymers enable significant improvements in device performance owing to enhanced interfacial polarization through dissimilar permittivity and conductivity between each layer, resulting in self-powered high-performance wearable devices. Moreover, novel triboelectric polymers with unique chemical structures or nano-additives can control interfacial polarization, allowing wearable devices to respond to multiple external stimuli. This review summarizes the recent insights into multilayered functional triboelectric polymers, including their fundamental dielectric principles and diverse applications. Full article

(This article belongs to the Special Issue Functional Polymers for Optic/Electronic Applications)

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19 pages, 5576 KiB

Open AccessArticle

A Self-Powered DSSH Circuit with MOSFET Threshold Voltage Management for Piezoelectric Energy Harvesting

by Liao Wu, Xinhui Wang and Minghua Xie

Micromachines 2023, 14(8), 1639; https://doi.org/10.3390/mi14081639 - 20 Aug 2023

Viewed by 921

Abstract

This paper presents a piezoelectric (PE) energy harvesting circuit based on the DSSH (double synchronized switch harvesting) principle. The circuit consisted of a rectifier and a DC–DC circuit, which achieves double synchronized switch operation for the PE transducer in each vibration half-cycle. One [...] Read more.

This paper presents a piezoelectric (PE) energy harvesting circuit based on the DSSH (double synchronized switch harvesting) principle. The circuit consisted of a rectifier and a DC–DC circuit, which achieves double synchronized switch operation for the PE transducer in each vibration half-cycle. One of the main challenges of the DSSH scheme was precisely controlling the switch timing in the second loop of the resonant loops. The proposed circuit included a MOS transistor in the second loop to address this challenge. It utilized its threshold voltage to manage the stored energy in the intermediate capacitor per vibration half-cycle to simplify the controller for the DSSH circuit. The circuit can operate under either the DSSH scheme or the ESSH (enhanced synchronized switch harvesting) scheme, depending on the value of the intermediate capacitor. In the DSSH scheme, the following DC–DC circuit reused the rectifier’s two diodes for a short period. The prototype circuit was implemented using 16 discrete components. The proposed circuit can be self-powered and started up without a battery. The experimental results showed that the proposed circuit increased the power harvested from the PE transducer compared to the full-bridge (FB) rectifier. With two different intermediate capacitors of 100 nF and 320 nF, the proposed circuit achieved power increases of 3.2 and 2.7 times, respectively. The charging efficiency of the proposed circuit was improved by a factor of 5.1 compared to the typical DSSH circuit. Full article

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

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35 pages, 3159 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Flexible and Stretchable Pressure Sensors: From Basic Principles to State-of-the-Art Applications

by Thara Seesaard and Chatchawal Wongchoosuk

Micromachines 2023, 14(8), 1638; https://doi.org/10.3390/mi14081638 - 20 Aug 2023

Cited by 7 | Viewed by 5600

Abstract

Flexible and stretchable electronics have emerged as highly promising technologies for the next generation of electronic devices. These advancements offer numerous advantages, such as flexibility, biocompatibility, bio-integrated circuits, and light weight, enabling new possibilities in diverse applications, including e-textiles, smart lenses, healthcare technologies, [...] Read more.

Flexible and stretchable electronics have emerged as highly promising technologies for the next generation of electronic devices. These advancements offer numerous advantages, such as flexibility, biocompatibility, bio-integrated circuits, and light weight, enabling new possibilities in diverse applications, including e-textiles, smart lenses, healthcare technologies, smart manufacturing, consumer electronics, and smart wearable devices. In recent years, significant attention has been devoted to flexible and stretchable pressure sensors due to their potential integration with medical and healthcare devices for monitoring human activity and biological signals, such as heartbeat, respiratory rate, blood pressure, blood oxygen saturation, and muscle activity. This review comprehensively covers all aspects of recent developments in flexible and stretchable pressure sensors. It encompasses fundamental principles, force/pressure-sensitive materials, fabrication techniques for low-cost and high-performance pressure sensors, investigations of sensing mechanisms (piezoresistivity, capacitance, piezoelectricity), and state-of-the-art applications. Full article

(This article belongs to the Special Issue Feature Reviews in Micromachines 2023)

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32 pages, 7986 KiB

Open AccessReview

Breakthrough in Silicon Photonics Technology in Telecommunications, Biosensing, and Gas Sensing

by Muhammad Shahbaz, Muhammad A. Butt and Ryszard Piramidowicz

Micromachines 2023, 14(8), 1637; https://doi.org/10.3390/mi14081637 - 19 Aug 2023

Cited by 4 | Viewed by 2967

Abstract

Silicon photonics has been an area of active research and development. Researchers have been working on enhancing the integration density and intricacy of silicon photonic circuits. This involves the development of advanced fabrication techniques and novel designs to enable more functionalities on a [...] Read more.

Silicon photonics has been an area of active research and development. Researchers have been working on enhancing the integration density and intricacy of silicon photonic circuits. This involves the development of advanced fabrication techniques and novel designs to enable more functionalities on a single chip, leading to higher performance and more efficient systems. In this review, we aim to provide a brief overview of the recent advancements in silicon photonic devices employed for telecommunication and sensing (biosensing and gas sensing) applications. Full article

(This article belongs to the Special Issue Silicon Photonic Devices and Integration)

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26 pages, 4978 KiB

Open AccessReview

Junction Temperature Optical Sensing Techniques for Power Switching Semiconductors: A Review

by Ridwanullahi Isa, Jawad Mirza, Salman Ghafoor, Mohammed Zahed Mustafa Khan and Khurram Karim Qureshi

Micromachines 2023, 14(8), 1636; https://doi.org/10.3390/mi14081636 - 19 Aug 2023

Cited by 2 | Viewed by 1401

Abstract

Recent advancements in power electronic switches provide effective control and operational stability of power grid systems. Junction temperature is a crucial parameter of power-switching semiconductor devices, which needs monitoring to facilitate reliable operation and thermal control of power electronics circuits and ensure reliable [...] Read more.

Recent advancements in power electronic switches provide effective control and operational stability of power grid systems. Junction temperature is a crucial parameter of power-switching semiconductor devices, which needs monitoring to facilitate reliable operation and thermal control of power electronics circuits and ensure reliable performance. Over the years, various junction temperature measurement techniques have been developed, engaging both non-optical and optical-based methods, highlighting their advancements and challenges. This review focuses on several optical sensing-based junction temperature measuring techniques used for power-switching devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated-gate bipolar transistors (IGBTs). A comprehensive summary of recent developments in infrared camera (IRC), thermal sensitive optical parameter (TSOP), and fiber Bragg grating (FBG) temperature sensing techniques is provided, shedding light on their merits and challenges while providing a few possible future solutions. In addition, calibration methods and remedies for obtaining accurate measurements are discussed, thus providing better insight and directions for future research. Full article

(This article belongs to the Special Issue Optical Sensing and Devices, 2nd Edition)

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16 pages, 9100 KiB

Open AccessArticle

Study on the Effect of Cold Deformation and Heat Treatment on the Properties of Cu-Ag Alloy Wire

by Xuefeng Wu, Hewei Jia, Junling Fan, Jun Cao and Chenghao Su

Micromachines 2023, 14(8), 1635; https://doi.org/10.3390/mi14081635 - 19 Aug 2023

Viewed by 864

Abstract

The effects of various drawing parameters and annealing processes on the structure and properties of Cu-Ag wires, containing 1 wt% silver, were investigated using specialized equipment including fine wire-drawing machines, very fine wire-drawing machines, heat treatment equipment, tensile testing machines, microcomputer-controlled electronic universal [...] Read more.

The effects of various drawing parameters and annealing processes on the structure and properties of Cu-Ag wires, containing 1 wt% silver, were investigated using specialized equipment including fine wire-drawing machines, very fine wire-drawing machines, heat treatment equipment, tensile testing machines, microcomputer-controlled electronic universal testers, resistance testers, and scanning electron microscopes. The results revealed that continuous drawing of Cu-1%Ag alloy wires led to elongation of the grains, resulting in a uniform and tightly fibrous microstructure. Moreover, the tensile strength of the alloy wire increased from 670 MPa to 783.9 MPa after a single pass with a deformation of 14%. Subsequently, when the wire was drawn at a speed of 500 m/min, the tensile strength further increased to 820.1 MPa. After annealing the Փ0.08 mm Cu-1% Ag alloy wire, an increase in annealing temperature up to 500 °C resulted in the wire’s tensile strength decreasing from 820.1 MPa to 377.5 MPa. Simultaneously, the elongation increased from 1.94% to 15.21%, and the resistivity decreased from 1.931 × 10⁻⁸ Ω·m to 1.723 × 10⁻⁸ Ω·m. Additionally, when annealing was conducted at a rate of 80 m/min, the wire resistivity dropped to 1.635 × 10⁻⁸ Ω·m. Full article

(This article belongs to the Special Issue Advanced Packaging for Microsystem Applications, 2nd Edition)

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11 pages, 2420 KiB

Open AccessArticle

A Mechanical Evaluation of a Robot-Assisted Cutting Cornea Based on Force Response

by Qinran Zhang, Jingyu Zhao, Sikai Wang, Shijing Deng and Peng Su

Micromachines 2023, 14(8), 1634; https://doi.org/10.3390/mi14081634 - 19 Aug 2023

Cited by 1 | Viewed by 828

Abstract

The aim of this paper is to propose laws of trephine operation based on a robot-assisted cutting cornea in order to obtain better microsurgical effects for keratoplasty. Using a trephine robot integrated with a microforce sensor and a handheld trephine manipulator, robotic and [...] Read more.

The aim of this paper is to propose laws of trephine operation based on a robot-assisted cutting cornea in order to obtain better microsurgical effects for keratoplasty. Using a trephine robot integrated with a microforce sensor and a handheld trephine manipulator, robotic and manual experiments were performed, with porcine corneas as the test subjects. The effect of trephine operational parameters on the results reflected by the biomechanical response is discussed, and the parameters include linear velocity, rotating angle, and angular velocity. Using probability density functions, the distributions of the manual operational parameters show some randomness, and there is a large fluctuation in the trephine force during the experiments. The biomechanical response shows regular trends in the robotic experiments even under different parameters, and compared to manual trephination, the robot may perform the operation of trephine cornea cutting more stably. Under different operational parameters, the cutting force shows different trends, and the optimal initial parameters that result in better trephine effects can be obtained based on the trends. Based on this derived law, the operational parameters can be set in robotic trephination, and surgeons can also be specially trained to achieve a better microsurgical result. Full article

(This article belongs to the Special Issue Recent Advance in Medical and Rehabilitation Robots)

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17 pages, 3760 KiB

Open AccessArticle

An Analytical Model of Dynamic Power Losses in eGaN HEMT Power Devices

by Jianming Lei, Yangyi Liu, Zhanmin Yang, Yalin Chen, Dunjun Chen, Liang Xu and Jing Yu

Micromachines 2023, 14(8), 1633; https://doi.org/10.3390/mi14081633 - 18 Aug 2023

Viewed by 899

Abstract

In this work, we present an analytical model of dynamic power losses for enhancement-mode AlGaN/GaN high-electron-mobility transistor power devices (eGaN HEMTs). To build this new model, the dynamic on-resistance (R_dson) is first accurately extracted via our extraction circuit based on [...] Read more.

In this work, we present an analytical model of dynamic power losses for enhancement-mode AlGaN/GaN high-electron-mobility transistor power devices (eGaN HEMTs). To build this new model, the dynamic on-resistance (R_dson) is first accurately extracted via our extraction circuit based on a double-diode isolation (DDI) method using a high operating frequency of up to 1 MHz and a large drain voltage of up to 600 V; thus, the unique problem of an increase in the dynamic R_dson is presented. Then, the impact of the current operation mode on the on/off transition time is evaluated via a dual-pulse-current-mode test (DPCT), including a discontinuous conduction mode (DCM) and a continuous conduction mode (CCM); thus, the transition time is revised for different current modes. Afterward, the discrepancy between the drain current and the real channel current is qualitative investigated using an external shunt capacitance (ESC) method; thus, the losses due to device parasitic capacitance are also taken into account. After these improvements, the dynamic model will be more compatible for eGaN HEMTs. Finally, the dynamic power losses calculated via this model are found to be in good agreement with the experimental results. Based on this model, we propose a superior solution with a quasi-resonant mode (QRM) to achieve lossless switching and accelerated switching speeds. Full article

(This article belongs to the Special Issue GaN-Based Semiconductor Devices, Volume II)

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15 pages, 2915 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Simultaneous Hydrostatic and Compressive Loading System for Mimicking the Mechanical Environment of Living Cartilage Tissue

by Minki Chang, Yosuke Takahashi, Kyosuke Miyahira, Yuma Omuro, Kevin Montagne, Ryusei Yamada, Junki Gondo, Yu Kambe, Masashi Yasuno, Noriyasu Masumoto, Takashi Ushida and Katsuko S. Furukawa

Micromachines 2023, 14(8), 1632; https://doi.org/10.3390/mi14081632 - 18 Aug 2023

Viewed by 849

Abstract

In vivo, articular cartilage tissue is surrounded by a cartilage membrane, and hydrostatic pressure (HP) and compressive strain increase simultaneously with the compressive stress. However, it has been impossible to investigate the effects of simultaneous loading in vitro. In this study, a bioreactor [...] Read more.

In vivo, articular cartilage tissue is surrounded by a cartilage membrane, and hydrostatic pressure (HP) and compressive strain increase simultaneously with the compressive stress. However, it has been impossible to investigate the effects of simultaneous loading in vitro. In this study, a bioreactor capable of applying compressive stress under HP was developed to reproduce ex vivo the same physical loading environment found in cartilage. First, a HP stimulation unit was constructed to apply a cyclic HP pressure-resistant chamber by controlling a pump and valve. A compression-loading mechanism that can apply compressive stress using an electromagnetic force was implemented in the chamber. The synchronization between the compression and HP units was evaluated, and the stimulation parameters were quantitatively evaluated. Physiological HP and compressive strain were applied to the chondrocytes encapsulated in alginate and gelatin gels after applying high HP at 25 MPa, which induced damage to the chondrocytes. It was found that compressive stimulation increased the expression of genes related to osteoarthritis. Furthermore, the simultaneous application of compressive strain and HP, which is similar to the physiological environment in cartilage, had an inhibitory effect on the expression of genes related to osteoarthritis. HP alone also suppressed the expression of osteoarthritis-related genes. Therefore, the simultaneous hydrostatic and compressive stress-loading device developed to simulate the mechanical environment in vivo may be an important tool for elucidating the mechanisms of disease onset and homeostasis in cartilage. Full article

(This article belongs to the Topic Materials, Structure Designs and Device Fabrications for Highly Efficient/Long Lifetime Organic Light-Emitting Diodes)

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12 pages, 5009 KiB

Open AccessArticle

A Low-Cost Multibeam Switching Antenna Using Reconfigurable Hybrid Metasurface for Beamforming Applications

by Lili Sheng, Yumei Luo, Gangxin Ning, Liang Meng and Weiping Cao

Micromachines 2023, 14(8), 1631; https://doi.org/10.3390/mi14081631 - 18 Aug 2023

Viewed by 914

Abstract

In this paper, we proposed a multibeam switching antenna based on a low-cost reconfigurable hybrid metasurface applied for beamforming systems. The antenna consists of two parts: a microstrip feed antenna and a transmission hybrid metasurface. The latter is composed of three types of [...] Read more.

In this paper, we proposed a multibeam switching antenna based on a low-cost reconfigurable hybrid metasurface applied for beamforming systems. The antenna consists of two parts: a microstrip feed antenna and a transmission hybrid metasurface. The latter is composed of three types of units with different amplitude and phase responses to electromagnetic waves so as to control the beams of the feed antenna. Sixteen PIN diodes are arranged in the metasurface with a simple bias network. When two different direct-current voltages are applied to the PIN diodes, the antenna can dynamically switch between two beams and four beams. For demonstration, the proposed antenna is fabricated, and the measured results show that the antenna operates at 9.07–9.42 GHz (−10 dB bandwidth) with a total size of 1.80λ₀ × 1.52λ₀ × 0.22λ₀ (λ₀ corresponds to the wavelength of 9.28 GHz in free space). With the merits of a compact structure, low cost and good radiation performance, the proposed design is suitable for beamforming applications. Full article

(This article belongs to the Special Issue Metasurfaces: Design, Fabrication and Applications)

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2 pages, 162 KiB

Open AccessEditorial

Editorial for the Special Issue on Recent Advances in Reactive Ion Etching and Applications of High-Aspect-Ratio Microfabrication

by Lucia Romano and Konstantins Jefimovs

Micromachines 2023, 14(8), 1630; https://doi.org/10.3390/mi14081630 - 18 Aug 2023

Viewed by 687

Abstract

Reactive ion etching (RIE) is the dominating technology for micromachining semiconductors with a high aspect ratio (HAR) [...] Full article

(This article belongs to the Special Issue Recent Advances in Reactive Ion Etching and Applications of High-Aspect-Ratio Microfabrication)

16 pages, 3491 KiB

Open AccessArticle

Adsorption of Preformed Microgel–Enzyme Complexes as a Novel Strategy toward Engineering Microgel-Based Enzymatic Biosensors

by Larisa V. Sigolaeva, Anna A. Shalybkova, Timur Z. Sharifullin and Dmitry V. Pergushov

Micromachines 2023, 14(8), 1629; https://doi.org/10.3390/mi14081629 - 18 Aug 2023

Cited by 1 | Viewed by 1036

Abstract

A novel approach to surface modification, which consists of the adsorption of microgel–enzyme complexes preformed in solution, is highlighted. Accordingly, the microgel–enzyme complexes were formed due to the electrostatic interaction of the oppositely charged interacting components, that is, a cationic poly(N-isopropylacrylamide)-based [...] Read more.

A novel approach to surface modification, which consists of the adsorption of microgel–enzyme complexes preformed in solution, is highlighted. Accordingly, the microgel–enzyme complexes were formed due to the electrostatic interaction of the oppositely charged interacting components, that is, a cationic poly(N-isopropylacrylamide)-based microgel and glucose oxidase taken as a model enzyme. The spontaneous adsorption of the prepared microgel–enzyme complexes, examined by means of quartz crystal microbalance with dissipation monitoring and atomic force microscopy, was observed, resulting in the formation of well-adhered microgel–enzyme coatings. Further, the preformed microgel–enzyme complexes were adsorbed onto the modified graphite-based screen-printed electrodes, and their enzymatic responses were determined by means of amperometry, demonstrating a remarkable analytical performance toward the quantification of β-D-glucose in terms of high sensitivity (0.0162 A × M⁻¹ × cm⁻²), a low limit of detection (1 μM), and an expanded linear range (1–2000 μM). The fabricated microgel–enzyme biosensor constructs were found to be very stable against manifold-repeated measurements. Finally, the pH- or salt-induced release of glucose oxidase from the adsorbed preformed microgel–enzyme complexes was demonstrated. The findings obtained for the microgel–enzyme coatings prepared via adsorption of the preformed microgel–enzyme complexes were compared to those found for the microgel–enzyme coatings fabricated via a previously exploited two-stage sequential adsorption, which includes the adsorption of the microgel first, followed by the electrostatic binding of glucose oxidase by the adsorbed microgel. Full article

(This article belongs to the Special Issue Biosensors for Biomedical and Environmental Applications)

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13 pages, 7339 KiB

Open AccessArticle

Thin-Film Solar Energy Absorber Structure for Window Coatings for Self-Sufficient Futuristic Buildings

by Haitham Alsaif, Jonas Muheki, Naim Ben Ali, Kaouther Ghachem, Jaymit Surve and Shobhit K. Patel

Micromachines 2023, 14(8), 1628; https://doi.org/10.3390/mi14081628 - 17 Aug 2023

Cited by 2 | Viewed by 842

Abstract

Energy-efficient buildings are a new demand in the current era. In this paper, we present a novel metamaterial design aimed at achieving efficient solar energy absorption through a periodic MMA structure composed of a W-GaAs-W. The proposed structure can be implemented as the [...] Read more.

Energy-efficient buildings are a new demand in the current era. In this paper, we present a novel metamaterial design aimed at achieving efficient solar energy absorption through a periodic MMA structure composed of a W-GaAs-W. The proposed structure can be implemented as the window coating and in turn it can absorb the incident solar energy and, then, this energy can be used to fulfill the energy demand of the building. Our results reveal significant improvements, achieving an average absorptance of 96.94% in the spectral range. Furthermore, we explore the influence of the angle of incidence on the absorber’s response, demonstrating its angle-insensitive behavior with high absorption levels (above 90%) for incidence angles up to 60° for TE polarization and 40° for TM polarization. The proposed structure presents a significant advancement in metamaterial-based solar energy absorption. By exploring the effects of structural parameters and incident angles, we have demonstrated the optimized version of our proposed absorber. The potential applications of this metamaterial absorber in self-sufficient futuristic building technologies and self-sustaining systems offer new opportunities for harnessing solar energy and are a valuable contribution to future developments in the fields of metamaterials and renewable energy. Full article

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

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11 pages, 1877 KiB

Open AccessArticle

Digital Microfluidic Multiplex RT-qPCR for SARS-CoV-2 Detection and Variants Discrimination

by Kuan-Lun Ho, Jing Ding, Jia-Shao Fan, Wai Ning Tiffany Tsui, Jianfa Bai and Shih-Kang Fan

Micromachines 2023, 14(8), 1627; https://doi.org/10.3390/mi14081627 - 17 Aug 2023

Viewed by 984

Abstract

Continuous mutations have occurred in the genome of the SARS-CoV-2 virus since the onset of the COVID-19 pandemic. The increased transmissibility of the mutated viruses has not only imposed medical burdens but also prolonged the duration of the pandemic. A point-of-care (POC) platform [...] Read more.

Continuous mutations have occurred in the genome of the SARS-CoV-2 virus since the onset of the COVID-19 pandemic. The increased transmissibility of the mutated viruses has not only imposed medical burdens but also prolonged the duration of the pandemic. A point-of-care (POC) platform that provides multitarget detection will help to track and reduce disease transmissions. Here we detected and discriminated three genotypes of SARS-CoV-2, including the wildtype and two variants of concern (VOCs), the Delta variant and Omicron variant, through reverse transcription quantitative polymerase chain reaction (RT-qPCR) on a digital microfluidics (DMF)-based cartridge. Upon evaluating with the RNA samples of Omicron variant, the DMF RT-qPCR presented a sensitivity of 10 copies/μL and an amplification efficiency of 96.1%, capable for clinical diagnosis. When spiking with SARS-CoV-2 RNA (wildtype, Delta variant, or Omicron variant) and 18S rDNA, the clinical analog samples demonstrated accurate detection and discrimination of different SARS-CoV-2 strains in 49 min. Full article

(This article belongs to the Special Issue Emerging Micro and Nano Technologies in Advanced Point of Care (POC) Innovations)

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17 pages, 10541 KiB

Open AccessArticle

Longitudinal–Torsional Ultrasonic Grinding of GCr15: Development of Longitudinal–Torsional Ultrasonic System and Prediction of Surface Topography

by Huan Zhang, Ying Niu, Xiaofeng Jia, Shuaizhen Chu and Jingjing Niu

Micromachines 2023, 14(8), 1626; https://doi.org/10.3390/mi14081626 - 17 Aug 2023

Viewed by 794

Abstract

The common material of bearing rings is GCr15 bearing steel which is a typical difficult-to-machine material. As an important working surface of the bearing, the inner surface of the raceway plays a vital role in the performance of the bearing. As an important [...] Read more.

The common material of bearing rings is GCr15 bearing steel which is a typical difficult-to-machine material. As an important working surface of the bearing, the inner surface of the raceway plays a vital role in the performance of the bearing. As an important means to solve the high-performance manufacturing of difficult-to-machine materials, longitudinal–torsional ultrasonic processing is widely used in various types of processing. In the presented work, the basic size of the horn is obtained from the wave equation of the forced vibration, and the modal analysis and amplitude test are carried out to verify the rationality of the LUTG structure. Then, according to the probability density function of cutting thickness and the overlapping effect of adjacent abrasive trajectories, the LUTG surface topography prediction model is established by using the height formula of the surface residual material, and the model reliability is verified by using the orthogonal test. The error between the test results and the prediction model is within 13.2%. Finally, based on the response surface method, the optimal process parameters that can meet the requirements of low roughness (Ra) and high material removal rate (MRR) are screened, and the optimal combination of process parameters is obtained as follows:

A

= 4.5 μm,

n

= 6493.3 r/min,

a_{p}

= 28.4 μm, and

v_{f}

= 21.1 mm/min. Full article

(This article belongs to the Special Issue Ultra-Precision Machining of Difficult-to-Machine Materials)

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13 pages, 3276 KiB

Open AccessArticle

Migration Study of Dielectrophoretically Manipulated Red Blood Cells in Tapered Aluminium Microelectrode Array: A Pilot Study

by Muhammad Izzuddin Abd Samad, Darven Raj Ponnuthurai, Syazwani Izrah Badrudin, Mohd Anuar Mohd Ali, Mohd Azhar Abdul Razak, Muhamad Ramdzan Buyong and Rhonira Latif

Micromachines 2023, 14(8), 1625; https://doi.org/10.3390/mi14081625 - 17 Aug 2023

Viewed by 697

Abstract

Dielectrophoresis (DEP) is one of the microfluid-based techniques that can manipulate the red blood cells (RBC) for blood plasma separation, which is used in many medical screening/diagnosis applications. The tapered aluminium microelectrode array (TAMA) is fabricated for potential sensitivity enhancement of RBC manipulation [...] Read more.

Dielectrophoresis (DEP) is one of the microfluid-based techniques that can manipulate the red blood cells (RBC) for blood plasma separation, which is used in many medical screening/diagnosis applications. The tapered aluminium microelectrode array (TAMA) is fabricated for potential sensitivity enhancement of RBC manipulation in lateral and vertical directions. In this paper, the migration properties of dielectrophoretically manipulated RBC in TAMA platform are studied at different peak-to-peak voltage (Vpp) and duration supplied onto the microelectrodes. Positive DEP manipulation is conducted at 440 kHz with the RBC of 4.00 ± 0.2 µm average radius attracted to the higher electric field intensity regions, which are the microelectrodes. High percentage of RBC migration occurred at longer manipulation time and high electrode voltage. During DEP manipulation, the RBC are postulated to levitate upwards, experience the electro-orientation mechanism and form the pearl chains before migrating to the electrodes. The presence of external forces other than the dielectrophoretic force may also affect the migration response of RBC. The safe operating limit of 10 Vpp and manipulation duration of ≤50 s prevent RBC rupture while providing high migration percentage. It is crucial to define the safe working region for TAMA devices that manipulate small RBC volume (~10 µL). Full article

(This article belongs to the Special Issue Micromachines for Dielectrophoresis, 3rd Edition)

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9 pages, 2009 KiB

Open AccessCommunication

Classification-Based Evaluation of Multi-Ingredient Dish Using Graphene-Modified Interdigital Electrodes

by Hongwu Zhu, Yongyuan Xu, Shengkai Liu, Xuchun He and Ning Ding

Micromachines 2023, 14(8), 1624; https://doi.org/10.3390/mi14081624 - 17 Aug 2023

Viewed by 807

Abstract

A taste sensor with global selectivity can be used to discriminate taste of foods and provide evaluations. Interfaces that could interact with broad food ingredients are beneficial for data collection. Here, we prepared electrochemically reduced graphene oxide (ERGO)-modified interdigital electrodes. The interfaces of [...] Read more.

A taste sensor with global selectivity can be used to discriminate taste of foods and provide evaluations. Interfaces that could interact with broad food ingredients are beneficial for data collection. Here, we prepared electrochemically reduced graphene oxide (ERGO)-modified interdigital electrodes. The interfaces of modified electrodes showed good sensitivity towards cooking condiments in mixed multi-ingredients solutions under electrochemical impedance spectroscopy (EIS). A database of EIS of cooking condiments was established. Based on the principal component analysis (PCA), subsets of three taste dimensions were classified, which could distinguish an unknown dish from a standard dish. Further, we demonstrated the effectiveness of the electrodes on a typical dish of scrambled eggs with tomato. Our kind of electronic tongue did not measure the quantitation of each ingredient, instead relying on the database and classification algorithm. This method is facile and offers a universal approach to simultaneously identifying multiple ingredients. Full article

(This article belongs to the Special Issue Functional Nanomaterials: Self-Assembly and Applications)

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14 pages, 4790 KiB

Open AccessArticle

Combined Temperature Compensation Method for Closed-Loop Microelectromechanical System Capacitive Accelerometer

by Guowen Liu, Yu Liu, Zhaohan Li, Zhikang Ma, Xiao Ma, Xuefeng Wang, Xudong Zheng and Zhonghe Jin

Micromachines 2023, 14(8), 1623; https://doi.org/10.3390/mi14081623 - 17 Aug 2023

Viewed by 825

Abstract

This article describes a closed-loop detection MEMS accelerometer for acceleration measurement. This paper analyzes the working principle of MEMS accelerometers in detail and explains the relationship between the accelerometer zero bias, scale factor and voltage reference. Therefore, a combined compensation method is designed [...] Read more.

This article describes a closed-loop detection MEMS accelerometer for acceleration measurement. This paper analyzes the working principle of MEMS accelerometers in detail and explains the relationship between the accelerometer zero bias, scale factor and voltage reference. Therefore, a combined compensation method is designed via reference voltage source compensation and terminal temperature compensation of the accelerometer, which comprehensively improves the performance over a wide temperature range of the accelerometer. The experiment results show that the initial range is reduced from 3679 ppm to 221 ppm with reference voltage source compensation, zero-bias stability of the accelerometer over temperature is increased by 14.3% on average and the scale factor stability over temperature is increased by 88.2% on average. After combined compensation, one accelerometer zero-bias stability over temperature was reduced to 40 μg and the scale factor stability over temperature was reduced to 16 ppm, the average value of the zero-bias stability over temperature was reduced from 1764 μg to 36 μg, the average value of the scale factor stability over temperature was reduced from 2270 ppm to 25 ppm, the average stability of the zero bias was increased by 97.96% and the average stability of the scale factor was increased by 98.90%. Full article

(This article belongs to the Special Issue MEMS Inertial Device)

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18 pages, 7029 KiB

Open AccessArticle

Design and Additive Manufacturing of a Continuous Servo Pneumatic Actuator

by Gabriel Dämmer, Hartmut Bauer, Michael Lackner, Rüdiger Neumann, Alexander Hildebrandt and Zoltán Major

Micromachines 2023, 14(8), 1622; https://doi.org/10.3390/mi14081622 - 17 Aug 2023

Viewed by 1346

Abstract

Despite an emerging interest in soft and rigid pneumatic lightweight robots, the pneumatic rotary actuators available to date either are unsuitable for servo pneumatic applications or provide a limited angular range. This study describes the functional principle, design, and manufacturing of a servo [...] Read more.

Despite an emerging interest in soft and rigid pneumatic lightweight robots, the pneumatic rotary actuators available to date either are unsuitable for servo pneumatic applications or provide a limited angular range. This study describes the functional principle, design, and manufacturing of a servo pneumatic rotary actuator that is suitable for continuous rotary motion and positioning. It contains nine radially arranged linear bellows actuators with rollers that push forward a cam profile. Proportional valves and a rotary encoder are used to control the bellows pressures in relation to the rotation angle. Introducing freely programmable servo pneumatic commutation increases versatility and allows the number of mechanical components to be reduced in comparison to state-of-the-art designs. The actuator presented is designed to be manufacturable using a combination of standard components, selective laser sintering, elastomer molding with novel multi-part cores and basic tools. Having a diameter of 110 mm and a width of 41 mm, our prototype weighs less than 500 g, produces a torque of 0.53 Nm at 1 bar pressure and a static positioning accuracy of 0.31° with no limit of angular motion. By providing a description of design, basic kinematic equations, manufacturing techniques, and a proof of concept, we enable the reader to envision and explore future applications. Full article

(This article belongs to the Special Issue Soft Actuators: Design, Fabrication and Applications)

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13 pages, 4756 KiB

Open AccessArticle

Electrohydrodynamic Printed Ultra-Micro AgNPs Thin Film Temperature Sensors Array for High-Resolution Sensing

by Yingping He, Lanlan Li, Zhixuan Su, Lida Xu, Maocheng Guo, Bowen Duan, Wenxuan Wang, Bo Cheng, Daoheng Sun and Zhenyin Hai

Micromachines 2023, 14(8), 1621; https://doi.org/10.3390/mi14081621 - 17 Aug 2023

Viewed by 1121

Abstract

Current methods for thin film sensors preparation include screen printing, inkjet printing, and MEMS (microelectromechanical systems) techniques. However, their limitations in achieving sub-10 μm line widths hinder high-density sensors array fabrication. Electrohydrodynamic (EHD) printing is a promising alternative due to its ability to [...] Read more.

Current methods for thin film sensors preparation include screen printing, inkjet printing, and MEMS (microelectromechanical systems) techniques. However, their limitations in achieving sub-10 μm line widths hinder high-density sensors array fabrication. Electrohydrodynamic (EHD) printing is a promising alternative due to its ability to print multiple materials and multilayer structures with patterned films less than 10 μm width. In this paper, we innovatively proposed a method using only EHD printing to prepare ultra-micro thin film temperature sensors array. The sensitive layer of the four sensors was compactly integrated within an area measuring 450 μm × 450 μm, featuring a line width of less than 10 μm, and a film thickness ranging from 150 nm to 230 nm. The conductive network of silver nanoparticles exhibited a porosity of 0.86%. After a 17 h temperature-resistance test, significant differences in the performance of the four sensors were observed. Sensor 3 showcased relatively superior performance, boasting a fitted linearity of 0.99994 and a TCR of 937.8 ppm/°C within the temperature range of 20 °C to 120 °C. Moreover, after the 17 h test, a resistance change rate of 0.17% was recorded at 20 °C. Full article

(This article belongs to the Special Issue Flexible and Wearable Sensors, 2nd Edition)

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13 pages, 14259 KiB

Open AccessArticle

Single Event Upset Study of 22 nm Fully Depleted Silicon-on-Insulator Static Random Access Memory with Charge Sharing Effect

by Chenyu Yin, Tianzhi Gao, Hao Wei, Yaolin Chen and Hongxia Liu

Micromachines 2023, 14(8), 1620; https://doi.org/10.3390/mi14081620 - 17 Aug 2023

Viewed by 831

Abstract

In this paper, the single event effect of 6T-SRAM is simulated at circuit level and device level based on a 22 nm fully depleted silicon-on-insulator (FDSOI) process, and the effects of charge sharing and bipolar amplification are considered in device-level simulation. The results [...] Read more.

In this paper, the single event effect of 6T-SRAM is simulated at circuit level and device level based on a 22 nm fully depleted silicon-on-insulator (FDSOI) process, and the effects of charge sharing and bipolar amplification are considered in device-level simulation. The results demonstrate that, under the combined influence of these two effects, the circuit’s upset threshold and critical charge decreased by 15.4% and 23.5%, respectively. This indicates that the charge sharing effect exacerbates the single event effects. By analyzing the incident conditions of two different incident radius particles, it is concluded that the particles with a smaller incident radius have a worse impact on the SRAM circuit, and are more likely to cause the single event upset in the circuit, indicating that the ionization distribution generated by the incident particle affects the charge collection. Full article

(This article belongs to the Section D1: Semiconductor Devices)

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