Special Issue "Smart Sensor 2021"

A special issue of Micromachines (ISSN 2072-666X).

Deadline for manuscript submissions: closed (31 May 2022) | Viewed by 8689

Special Issue Editors

Prof. Dr. Yuan-Jen Chang
E-Mail Website
Guest Editor
Department of Mechanical Engineering, National Yunlin University of Science and Technology, Douliou, Yunlin 64002, Taiwan
Interests: micro-/nanosystem design; micro-/nanofabrication; nonconventional machining; nanoimprint; laser micromachining
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Chih-Ting Lin
E-Mail Website
Guest Editor
Department of Electrical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan
Interests: bio-NEMS; biochip; nanofabrication; biomolecular detection technology

Special Issue Information

Dear Colleagues,

The 2021 International Conference on Smart Sensors (ICSS) will be held on 5–6 July, 2021, at the GIS NTU Convention Center, Taipei, Taiwan (https://icss2021.azurewebsites.net/). The conference is a joint event of the 26th Symposium of Association for Chemical Sensors in Taiwan and the 24th Nano Engineering and Microsystem Technology Conference.

This Special Issue will publish both selected papers from ICSS 2021 and external papers. The topics to be covered include but are not limited to:

  1. sensing materials, processing, and fabrications;
  2. physical sensors and microsystems;
  3. chemical sensors and microsystems;
  4. optical and acoustic sensors;
  5. biosensors including in vitro diagnoses;
  6. wearable and in vivo medical microsystems;
  7. RF MEMS and resonators;
  8. microfluidic technologies;
  9. actuators and microsystems;
  10. power and energy management of sensor systems;
  11. sensor systems: interface and data processing;
  12. applications of sensor and actuator systems: IoT and networks;
  13. Others.

We encourage both original research papers and comprehensive review articles to be submitted to this Special Issue.

Prof. Dr. Yuan-Jen Chang
Prof. Dr. Chih-Ting Lin
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Micromachines is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (8 papers)

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Research

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Communication
Real-Time Micro-Monitoring of Surface Temperature and Strain of Magnesium Hydrogen Tank through Self-Made Two-In-One Flexible High-Temperature Micro-Sensor
Micromachines 2022, 13(9), 1370; https://doi.org/10.3390/mi13091370 - 23 Aug 2022
Viewed by 552
Abstract
The adsorption and desorption of hydrogen in the magnesium powder hydrogen tank should take place in an environment with a temperature higher than 250 °C. High temperature and high strain will lead to reactive hydrogen leakage from the magnesium hydrogen tank due to [...] Read more.
The adsorption and desorption of hydrogen in the magnesium powder hydrogen tank should take place in an environment with a temperature higher than 250 °C. High temperature and high strain will lead to reactive hydrogen leakage from the magnesium hydrogen tank due to tank rupture. Therefore, it is very important to monitor in real time the volume expansion, temperature change, and strain change on the surface of the magnesium hydrogen tank. In this study, the micro-electro-mechanical systems (MEMS) technology was used to innovatively integrate the micro-temperature sensor and the micro-strain sensor into a two-in-one flexible high-temperature micro-sensor with a small size and high sensitivity. It can be placed on the surface of the magnesium hydrogen tank for real-time micro-monitoring of the effect of hydrogen pressure and powder hydrogen absorption expansion on the strain of the hydrogen storage tank. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Article
Flexible, Multifunctional Micro-Sensor Applied to Internal Measurement and Diagnosis of Vanadium Flow Battery
Micromachines 2022, 13(8), 1193; https://doi.org/10.3390/mi13081193 - 28 Jul 2022
Cited by 1 | Viewed by 530
Abstract
The vanadium redox flow battery (VRFB) system is an emerging energy storage technology with many advantages, such as high efficiency, long life, and high safety. However, during the power-generation process, if local high temperature is generated, the rate of ions passing through the [...] Read more.
The vanadium redox flow battery (VRFB) system is an emerging energy storage technology with many advantages, such as high efficiency, long life, and high safety. However, during the power-generation process, if local high temperature is generated, the rate of ions passing through the membrane will increase. In addition, it will also cause vanadium pentoxide molecules (V2O5) to exist in the solid state. Once the solid is formed, it will affect the flow of the vanadium electrolyte, which will eventually cause the temperature of the VRFB to continue to rise. According to the various physical parameters of VRFB shown in the literature, they have a significant impact on the efficiency and life of VRFB. Therefore, this research proposes to develop flexible multifunction (voltage, current, temperature, and flow) micro-sensors using micro-electro-mechanical systems (MEMS) technology to meet the need for real-time micro-diagnosis in the VRFB. The device is embedded in the VRFB of real-time microscopic sensing and diagnosis. Its technical advantages are: (1) it can simultaneously locally measure four physical quantities of voltage, current, temperature, and flow; (2) due to its mall size it can be accurately embedded; (3) the high accuracy and sensitivity provides it with a fast response time; and (4) it possesses extreme environment resistance. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Article
Microwave-Assisted Solvent Bonding for Polymethyl Methacrylate Microfluidic Device
Micromachines 2022, 13(7), 1131; https://doi.org/10.3390/mi13071131 - 17 Jul 2022
Viewed by 769
Abstract
This paper demonstrated a microwave-assisted solvent bonding method that uses organic solvent to seal the thermoplastic substrates with microwave assistance. This direct bonding is a simple and straightforward process that starts with solvent application followed by microwave irradiation without the need for expensive [...] Read more.
This paper demonstrated a microwave-assisted solvent bonding method that uses organic solvent to seal the thermoplastic substrates with microwave assistance. This direct bonding is a simple and straightforward process that starts with solvent application followed by microwave irradiation without the need for expensive facilities or complex procedures. The organic solvent applied at the bonding interface is used in dissolving and dielectric heating of the thermoplastic surfaces to seal the thermoplastic substrates under microwave assistance. We evaluated acetone and ethanol to seal the polymethyl methacrylate (PMMA) microfluidic device. The bonding performance, such as bonding coverage, geometry stability, and bonding strength (tensile) were observed and compared with the oven-heating and non-heating control experiments under the same force applications. Results showed that the microwave-assisted solvent bonding method presents a high bonding yield (maximum > 99%) and bonding strength (maximum ~2.77 MPa) without microchannel distortion, which can be used for various microfluidic applications. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Article
Contactless Micro-Droplet Manipulation of Liquid Released from a Parallel Plate to an Open Region in Electrowetting-on-Dielectric Platform
Micromachines 2022, 13(6), 898; https://doi.org/10.3390/mi13060898 - 06 Jun 2022
Viewed by 718
Abstract
In electrowetting-on-dielectric (EWOD) platform, the transfer of droplets from the EWOD boundary region (top plate and bottom plate) to the open region is challenging. The challenge is due to the resistance-like surface tension, friction from the top-plate edge, and the so-called boundary. For [...] Read more.
In electrowetting-on-dielectric (EWOD) platform, the transfer of droplets from the EWOD boundary region (top plate and bottom plate) to the open region is challenging. The challenge is due to the resistance-like surface tension, friction from the top-plate edge, and the so-called boundary. For this purpose, we designed the top plate to minimize the friction resistance at the boundary. The experiment focused on Gibb’s formula and successfully transferred the liquid droplet between the top plate and bottom plate boundary region under a high voltage environment. The threshold voltage for the successful transportation of the droplet between the boundary is 250 V which provides strong pressure to drive the droplet. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Article
Process Parameter Prediction and Modeling of Laser Percussion Drilling by Artificial Neural Networks
Micromachines 2022, 13(4), 529; https://doi.org/10.3390/mi13040529 - 27 Mar 2022
Cited by 2 | Viewed by 1110
Abstract
Finding process parameters for laser-drilled blind holes often relies on an engineer’s experience and the trial-and-error method. However, determining such parameters should be possible using methodical calculations. Studies have already begun to examine the use of neural networks to improve the efficiency of [...] Read more.
Finding process parameters for laser-drilled blind holes often relies on an engineer’s experience and the trial-and-error method. However, determining such parameters should be possible using methodical calculations. Studies have already begun to examine the use of neural networks to improve the efficiency of this situation. This study extends the field of research by applying artificial neural networks (ANNs) to predict the required parameters for drilling stainless steel with a certain depth and diameter of blind holes, and it also pre-simulates the drilling result of these predicted parameters before actual laser processing. The pre-simulated drilling results were also compared with real-world observations after drilling the stainless steel. These experimental findings confirmed that the proposed method can be used to accurately select laser drilling parameters and predict results in advance. Being able to make these predictions successfully reduces time spent, manpower, and the number of trial-and-error shots required in the pre-processing phase. In addition to providing specific data for engineers to use, this method could also be used to develop a set of reference parameters, greatly simplifying the laser drilling process. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Article
Flexible Temperature Sensor Utilizing MWCNT Doped PEG-PU Copolymer Nanocomposites
Micromachines 2022, 13(2), 197; https://doi.org/10.3390/mi13020197 - 27 Jan 2022
Cited by 4 | Viewed by 1595
Abstract
In this study, polyethylene glycol (PEG) and polyurethane (PU)-based shape-stabilized copolymer nanocomposites were synthesized and utilized for developing low-cost and flexible temperature sensors. PU was utilized as a flexible structural material for loading a thermosensitive phase change PEG polymer by means of physical [...] Read more.
In this study, polyethylene glycol (PEG) and polyurethane (PU)-based shape-stabilized copolymer nanocomposites were synthesized and utilized for developing low-cost and flexible temperature sensors. PU was utilized as a flexible structural material for loading a thermosensitive phase change PEG polymer by means of physical mixing and chemical crosslinking. Furthermore, the introduction of multi-walled carbon nanotubes (MWCNT) as a conductive filler in the PEG-PU copolymer resulted in a nanocomposite with thermoresistive properties. MWCNT loading concentrations from 2 wt.% to 10 wt.% were investigated, to attain the optimum conductivity of the nanocomposite. Additionally, the effect of MWCNT loading concentration on the thermosensitive behavior of the nanocomposite was analyzed in the temperature range 25 °C to 50 °C. The thermosensitive properties of the physically mixed and crosslinked polymeric nanocomposites were compared by spin coating the respective nanocomposites on screen printed interdigitated (IDT) electrodes, to fabricate the temperature sensor. The chemically crosslinked MWCNT-PEG-PU polymeric nanocomposite showed an improved thermosensitive behavior in the range 25 °C to 50 °C, compared to the physically mixed nanocomposite. The detailed structural, morphological, thermal, and phase transition properties of the nanocomposites were investigated using XRD, FTIR, and DSC analysis. XRD and FTIR were used to analyze the crystallinity and PEG-PU bonding of the copolymer nanocomposite, respectively; while the dual phase (solid–liquid) transition of PEG was analyzed using DSC. The proposed nanocomposite-based flexible temperature sensor demonstrated excellent sensitivity, reliability and shows promise for a wide range of bio-robotic and healthcare applications. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Article
Low-Temperature Flexible Micro Hydrogen Sensor Embedded in a Proton Battery for Real-Time Microscopic Diagnosis
Micromachines 2021, 12(10), 1215; https://doi.org/10.3390/mi12101215 - 05 Oct 2021
Viewed by 1039
Abstract
The proton battery is a very novel emerging research area with practicability. The proton battery has charging and discharging functions. It not only electrolyzes water: the electrolyzed protons can be stored but also released, which are combined with oxygen to generate electricity, and [...] Read more.
The proton battery is a very novel emerging research area with practicability. The proton battery has charging and discharging functions. It not only electrolyzes water: the electrolyzed protons can be stored but also released, which are combined with oxygen to generate electricity, and the hydrogen is not required; the hydrogen ions will be released from the battery. According to the latest document, the multiple important physical parameters (e.g., hydrogen, voltage, current, temperature, humidity, and flow) inside the proton battery are unlikely to be obtained accurately and the multiple important physical parameters mutually influence the data; they have critical effects on the performance, life, and health status of the proton battery. At present, the proton battery is measured only from the outside to indirectly diagnose the health status of battery; the actual situation inside the proton battery cannot be obtained instantly and accurately. This study uses micro-electro-mechanical systems (MEMS) technology to develop a low-temperature micro hydrogen sensor, which is used for monitoring the internal condition of the proton battery and judging whether or not there is hydrogen leakage, so as to enhance the safety. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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Review

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Review
Review-Hysteresis in Carbon Nano-Structure Field Effect Transistor
Micromachines 2022, 13(4), 509; https://doi.org/10.3390/mi13040509 - 25 Mar 2022
Cited by 1 | Viewed by 1460
Abstract
In recent decades, the research of nano-structure devices (e.g., carbon nanotube and graphene) has experienced rapid growth. These materials have supreme electronic, thermal, optical and mechanical properties and have received widespread concern in different fields. It is worth noting that gate hysteresis behavior [...] Read more.
In recent decades, the research of nano-structure devices (e.g., carbon nanotube and graphene) has experienced rapid growth. These materials have supreme electronic, thermal, optical and mechanical properties and have received widespread concern in different fields. It is worth noting that gate hysteresis behavior of field effect transistors can always be found in ambient conditions, which may influence the transmission appearance. Many researchers have put forward various views on this question. Here, we summarize and discuss the mechanisms behind hysteresis, different influencing factors and improvement methods which help decrease or eliminate unevenness and asymmetry. Full article
(This article belongs to the Special Issue Smart Sensor 2021)
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