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14 pages, 5663 KiB

Open AccessArticle

An L-Slot Frequency Reconfigurable Antenna Based on MEMS Technology

by Yu Chen, Honglei Guo, Yanfei Liu, Jing Li, Yongxin Zhan, Qiannan Wu and Mengwei Li

Micromachines 2023, 14(10), 1945; https://doi.org/10.3390/mi14101945 - 18 Oct 2023

Viewed by 941

Given the shortage of spectrum resources and the demand for communication systems of diminutive size, multi-function, and adaptive characteristics, this paper proposes an L-slot frequency reconfigurable antenna based on the MEMS switch. The antenna size is 4.07 × 5.27 mm² and is [...] Read more.

Given the shortage of spectrum resources and the demand for communication systems of diminutive size, multi-function, and adaptive characteristics, this paper proposes an L-slot frequency reconfigurable antenna based on the MEMS switch. The antenna size is 4.07 × 5.27 mm² and is suitable for the U-band. The antenna structure consists of two RF MEMS switches, a Rogers RT5880 dielectric substrate, an L-slot patch, and a full-coverage ground. The switch is of a series contact structure and is arranged at the corner of an L-slot. By controlling the on and off state of the switch, the antenna can switch between four states of 42.36, 47.65, 53.13, and 56.72 GHz. According to the simulation results in CST STUDIO SUITE 2018, the maximum gain of the antenna is 7.90 dB, the impedance bandwidth of each state is above 1 GHz, and the direction is mainly consistent. The antenna can meet the demand for multi-frequency millimeter wave communication. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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15 pages, 1652 KiB

Open AccessArticle

Static and Eigenvalue Analysis of Electrostatically Coupled and Tunable Shallow Micro-Arches for Sensing-Based Applications

by Hassen M. Ouakad and Ayman M. Alneamy

Micromachines 2023, 14(5), 903; https://doi.org/10.3390/mi14050903 - 23 Apr 2023

Cited by 3 | Viewed by 968

Abstract

This paper investigated the mechanical performance of an electrostatically tunable microbeams-based resonators. The resonator was designed based on two initially-curved microbeams that are electrostatically coupled, offering the potential for improved performance compared to single-beam based resonators. Analytical models and simulation tools were developed [...] Read more.

This paper investigated the mechanical performance of an electrostatically tunable microbeams-based resonators. The resonator was designed based on two initially-curved microbeams that are electrostatically coupled, offering the potential for improved performance compared to single-beam based resonators. Analytical models and simulation tools were developed to optimize the resonator design dimensions and to predict its performance, including its fundamental frequency and motional characteristics. The results show that the electrostatically-coupled resonator exhibits multiple nonlinear phenomena including mode veering and snap-through motion. A coexistence of two stable branches of solutions for a straight beam case was even obtained due to the direct effect of the coupling electrostatic force with the other curved beam. Indeed, the results are promising for the better performance of coupled resonators compared to single-beam resonators and offer a platform for future MEMS applications including mode-localized based micro-sensors. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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16 pages, 6277 KiB

Open AccessArticle

An Engineering Method for Resonant Microcantilever Using Double-Channel Excitation and Signal Acquisition Based on LabVIEW

by Shanlai Wang, Zhi Cao, Xiaoyang Zhang, Haitao Yu and Lei Yao

Micromachines 2023, 14(4), 823; https://doi.org/10.3390/mi14040823 - 07 Apr 2023

Viewed by 1379

Abstract

Resonant microcantilevers have the advantages of ultra-high heating rates, analysis speed, ultra-low power consumption, temperature programming, and trace sample analysis when applied in TGA. However, the current single-channel testing system for resonant microcantilevers can only detect one sample at a time, and need [...] Read more.

Resonant microcantilevers have the advantages of ultra-high heating rates, analysis speed, ultra-low power consumption, temperature programming, and trace sample analysis when applied in TGA. However, the current single-channel testing system for resonant microcantilevers can only detect one sample at a time, and need two program heating tests to obtain the thermogravimetric curve of a sample. In many cases, it is desirable to obtain the thermogravimetric curve of a sample with a single-program heating test and to simultaneously detect multiple microcantilevers for testing multiple samples. To address this issue, this paper proposes a dual-channel testing method, where a microcantilever is used as a control group and another microcantilever is used as an experimental group, to obtain the thermal weight curve of the sample in a single program temperature ramp test. With the help of the LabVIEW’s convenient parallel running method, the functionality of simultaneously detecting two microcantilevers is achieved. Experimental validation showed that this dual-channel testing system can obtain the thermogravimetric curve of a sample with a single program heating test and detect two types of samples simultaneously. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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15 pages, 3984 KiB

Open AccessArticle

Sensitivity Enhancement of Tube-Integrated MEMS Flow Sensor Using Flexible Copper on Polyimide Substrate

by Tsuyoshi Tsukada, Ryusei Takigawa, Yoshihiro Hasegawa, Muhammad Salman Al Farisi and Mitsuhiro Shikida

Micromachines 2023, 14(1), 42; https://doi.org/10.3390/mi14010042 - 24 Dec 2022

Cited by 3 | Viewed by 1890

Abstract

A tube-integrated flow sensor is proposed in this study by integrating a micro-electro mechanical systems (MEMS) flow-sensing element and electrical wiring structure on the same copper on polyimide (COP) substrate. The substrate was rolled into a circular tube with the flow-sensing element installed [...] Read more.

A tube-integrated flow sensor is proposed in this study by integrating a micro-electro mechanical systems (MEMS) flow-sensing element and electrical wiring structure on the same copper on polyimide (COP) substrate. The substrate was rolled into a circular tube with the flow-sensing element installed at the center of the tube. The signal lines were simultaneously formed and connected to the Cu layer of the substrate during the fabrication of the sensing structure, thus simplifying the electrical connection process. Finally, by rolling the fabricated sensor substrate, the flow sensor device itself was transformed into a circular tube structure, which defined the airflow region. By implementing several slits on the substrate, the sensing element was successfully placed at the center of the tube where the flow velocity is maximum. Compared to the conventional sensor structure in which the sensor was placed on the inner wall surface of the tube, the sensitivity of the sensor was doubled. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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16 pages, 5642 KiB

Open AccessArticle

Research on Temperature Compensation of Multi-Channel Pressure Scanner Based on an Improved Cuckoo Search Optimizing a BP Neural Network

by Huan Wang, Qinghua Zeng, Zongyu Zhang and Hongfu Wang

Micromachines 2022, 13(8), 1351; https://doi.org/10.3390/mi13081351 - 19 Aug 2022

Cited by 7 | Viewed by 1637

Abstract

A multi-channel pressure scanner is an essential tool for measuring and acquiring various pressure parameters in aerospace applications. It is important to note, however, that the pressure sensor of each of these channels will drift significantly with the increase in the temperature range [...] Read more.

A multi-channel pressure scanner is an essential tool for measuring and acquiring various pressure parameters in aerospace applications. It is important to note, however, that the pressure sensor of each of these channels will drift significantly with the increase in the temperature range of the pressure measurement, and the output voltage of each of these channels will show nonlinear characteristics, which will constrain the improvements in the accuracy of the measurement. In the regression fitting process, it is difficult to fit nonlinear data with the traditional least-squares method, which leaves pressure measurement accuracy unsatisfactory. A temperature compensation method based on an improved cuckoo search optimizing a BP neural network for a multi-channel pressure scanner is proposed in this paper to improve pressure measurement accuracy in a wide temperature range. Using the chaotic simplex algorithm, we first improved the cuckoo search algorithm, then optimized the connection weights and thresholds of the BP neural network, and finally constructed an experimental calibration system to investigate the temperature compensation of the multi-channel pressure scanning valves in the −40 °C to 60 °C temperature range. The compensation test results show that the algorithm has a better compensation effect and is more suitable for the temperature compensation of multi-channel pressure scanners than the traditional least-squares method and the standard RBF and BP neural networks. The maximum full-scale error of all 32 channels is 0.02% FS (full-scale error) and below, which realizes its high-accuracy multi-point pressure measurement in a wide temperature range. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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20 pages, 12672 KiB

Open AccessArticle

Research on Gradient-Descent Extended Kalman Attitude Estimation Method for Low-Cost MARG

by Ning Liu, Wenhao Qi, Zhong Su, Qunzhuo Feng and Chaojie Yuan

Micromachines 2022, 13(8), 1283; https://doi.org/10.3390/mi13081283 - 09 Aug 2022

Cited by 1 | Viewed by 1310

Abstract

Aiming at the problem of the weak dynamic performance of the gradient descent method in the attitude and heading reference system, the susceptibility to the interference of accelerometers and magnetometers, and the complex calculation of the nonlinear Kalman Filter method, an extended Kalman [...] Read more.

Aiming at the problem of the weak dynamic performance of the gradient descent method in the attitude and heading reference system, the susceptibility to the interference of accelerometers and magnetometers, and the complex calculation of the nonlinear Kalman Filter method, an extended Kalman filter suitable for a low-cost magnetic, angular rate, and gravity (MARG) sensor system is proposed. The method proposed in this paper is a combination of a two-stage gradient descent algorithm and the extended Kalman filter (GDEKF). First, the accelerometer and magnetometer are used to correct the attitude angle according to the two-stage gradient descent algorithm. The obtained attitude quaternion is combined with the gyroscope measurement value as the observation vector of EKF and the calculated attitude of the gyroscope and the bias of the gyroscope are corrected. The elimination of the bias of the gyroscope can further improve the stability of the attitude observation results. Finally, the MARG sensor system was designed for mathematical model simulation and hardware-in-the-loop simulation to verify the performance of the filter. The results show that compared with the gradient descent method, it has better anti-interference performance and dynamic performance, and better measurement accuracy than the extended Kalman filter. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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15 pages, 8925 KiB

Open AccessArticle

Facile Fabrication of a Highly Sensitive and Robust Flexible Pressure Sensor with Batten Microstructures

by Xuefeng Zhang, Sheng Chang and Zhixue Tong

Micromachines 2022, 13(8), 1164; https://doi.org/10.3390/mi13081164 - 23 Jul 2022

Cited by 5 | Viewed by 1599

Abstract

As the foremost component of wearable devices, flexible pressure sensors require high sensitivity, wide operating ranges, and great stability. In this paper, a pressure sensor comprising a regular batten microstructure active layer is presented. First, the influences of the dimensional parameters of the [...] Read more.

As the foremost component of wearable devices, flexible pressure sensors require high sensitivity, wide operating ranges, and great stability. In this paper, a pressure sensor comprising a regular batten microstructure active layer is presented. First, the influences of the dimensional parameters of the microstructures on the performances of the sensors were investigated by the mechanical finite element method (FEM). Then, parameters were optimized and determined based on the results of this investigation. Next, active layers were prepared by molding multiwalled carbon nanotube/polyurethane (MWCNT/PU) conductive composite using a printed circuit board template. Finally, a resistive flexible pressure sensor was fabricated by combining an active layer and an interdigital electrode. With advantages in terms of the structure and materials, the sensor exhibited a sensitivity of up to 46.66 kPa⁻¹ in the range of 0–1.5 kPa and up to 6.67 kPa⁻¹ in the range of 1.5–7.5 kPa. The results of the experiments show that the designed flexible pressure sensor can accurately measure small pressures and realize real-time human physiological monitoring. Furthermore, the preparation method has the advantages of a low cost, simple design, and high consistency. Thus, it has potential to promote the development of flexible sensors, wearable devices, and other related devices. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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Review

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25 pages, 6125 KiB

Open AccessReview

Structural Engineering in Piezoresistive Micropressure Sensors: A Focused Review

by Yan Liu, Xin Jiang, Haotian Yang, Hongbo Qin and Weidong Wang

Micromachines 2023, 14(8), 1507; https://doi.org/10.3390/mi14081507 - 27 Jul 2023

Cited by 1 | Viewed by 1598

Abstract

The longstanding demands for micropressure detection in commercial and industrial applications have led to the rapid development of relevant sensors. As a type of long-term favored device based on microelectromechanical system technology, the piezoresistive micropressure sensor has become a powerful measuring platform owing [...] Read more.

The longstanding demands for micropressure detection in commercial and industrial applications have led to the rapid development of relevant sensors. As a type of long-term favored device based on microelectromechanical system technology, the piezoresistive micropressure sensor has become a powerful measuring platform owing to its simple operational principle, favorable sensitivity and accuracy, mature fabrication, and low cost. Structural engineering in the sensing diaphragm and piezoresistor serves as a core issue in the construction of the micropressure sensor and undertakes the task of promoting the overall performance for the device. This paper focuses on the representative structural engineering in the development of the piezoresistive micropressure sensor, largely concerning the trade-off between measurement sensitivity and nonlinearity. Functional elements on the top and bottom layers of the diaphragm are summarized, and the influences of the shapes and arrangements of the piezoresistors are also discussed. The addition of new materials endows the research with possible solutions for applications in harsh environments. A prediction for future tends is presented, including emerging advances in materials science and micromachining techniques that will help the sensor become a stronger participant for the upcoming sensor epoch. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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40 pages, 27383 KiB

Open AccessReview

A Focused Review on the Flexible Wearable Sensors for Sports: From Kinematics to Physiologies

by Lei Liu and Xuefeng Zhang

Micromachines 2022, 13(8), 1356; https://doi.org/10.3390/mi13081356 - 20 Aug 2022

Cited by 11 | Viewed by 3841

Abstract

As an important branch of wearable electronics, highly flexible and wearable sensors are gaining huge attention due to their emerging applications. In recent years, the participation of wearable devices in sports has revolutionized the way to capture the kinematical and physiological status of [...] Read more.

As an important branch of wearable electronics, highly flexible and wearable sensors are gaining huge attention due to their emerging applications. In recent years, the participation of wearable devices in sports has revolutionized the way to capture the kinematical and physiological status of athletes. This review focuses on the rapid development of flexible and wearable sensor technologies for sports. We identify and discuss the indicators that reveal the performance and physical condition of players. The kinematical indicators are mentioned according to the relevant body parts, and the physiological indicators are classified into vital signs and metabolisms. Additionally, the available wearable devices and their significant applications in monitoring these kinematical and physiological parameters are described with emphasis. The potential challenges and prospects for the future developments of wearable sensors in sports are discussed comprehensively. This review paper will assist both athletic individuals and researchers to have a comprehensive glimpse of the wearable techniques applied in different sports. Full article

(This article belongs to the Special Issue MEMS/NEMS for Sensing: Array, Integration, Intelligence and Application)

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