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18 pages, 7229 KiB

Open AccessArticle

Design and Algorithm Integration of High-Precision Adaptive Underwater Detection System Based on MEMS Vector Hydrophone

by Yan Liu, Boyuan Jing, Guojun Zhang, Jiayu Pei, Li Jia, Yanan Geng, Zhengyu Bai, Jie Zhang, Zimeng Guo, Jiangjiang Wang, Yuhao Huang, Lele Xu, Guochang Liu and Wendong Zhang

Micromachines 2024, 15(4), 514; https://doi.org/10.3390/mi15040514 - 12 Apr 2024

Viewed by 691

Abstract

Real-time DOA (direction of arrival) estimation of surface or underwater targets is of great significance to the research of marine environment and national security protection. When conducting real-time DOA estimation of underwater targets, it can be difficult to extract the prior characteristics of [...] Read more.

Real-time DOA (direction of arrival) estimation of surface or underwater targets is of great significance to the research of marine environment and national security protection. When conducting real-time DOA estimation of underwater targets, it can be difficult to extract the prior characteristics of noise due to the complexity and variability of the marine environment. Therefore, the accuracy of target orientation in the absence of a known noise is significantly reduced, thereby presenting an additional challenge for the DOA estimation of the marine targets in real-time. Aiming at the problem of real-time DOA estimation of acoustic targets in complex environments, this paper applies the MEMS vector hydrophone with a small size and high sensitivity to sense the conditions of the ocean environment and change the structural parameters in the adaptive adjustments system itself to obtain the desired target signal, proposes a signal processing method when the prior characteristics of noise are unknown. Theoretical analysis and experimental verification show that the method can achieve accurate real-time DOA estimation of the target, achieve an error within 3.1° under the SNR (signal-to-noise ratio) of the X channel of −17 dB, and maintain a stable value when the SNR continues to decrease. The results show that this method has a very broad application prospect in the field of ocean monitoring. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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14 pages, 5713 KiB

Open AccessArticle

Design of a Biaxial High-G Piezoresistive Accelerometer with a Tension–Compression Structure

by Peng Wang, Yujun Yang, Manlong Chen, Changming Zhang, Nan Wang, Fan Yang, Chunlei Peng, Jike Han and Yuqiang Dai

Micromachines 2023, 14(8), 1492; https://doi.org/10.3390/mi14081492 - 25 Jul 2023

Viewed by 895

Abstract

To meet the measurement needs of multidimensional high-g acceleration in fields such as weapon penetration, aerospace, and explosive shock, a biaxial piezoresistive accelerometer incorporating tension–compression is meticulously designed. This study begins by thoroughly examining the tension–compression measurement mechanism and designing the sensor’s sensitive [...] Read more.

To meet the measurement needs of multidimensional high-g acceleration in fields such as weapon penetration, aerospace, and explosive shock, a biaxial piezoresistive accelerometer incorporating tension–compression is meticulously designed. This study begins by thoroughly examining the tension–compression measurement mechanism and designing the sensor’s sensitive structure. A signal test circuit is developed to effectively mitigate cross-interference, taking into account the stress variation characteristics of the cantilever beam. Subsequently, the signal test circuit of anti-cross-interference is designed according to the stress variation characteristics of the cantilever beam. Next, the finite element method is applied to analyze the structure and obtain the performance indices of the range, vibration modes, and sensitivity of the sensor. Finally, the process flow and packaging scheme of the chip are analyzed. The results show that the sensor has a full range of 200,000 g, a sensitivity of 1.39 µV/g in the X direction and 1.42 µV/g in the Y direction, and natural frequencies of 509.8 kHz and 510.2 kHz in the X and Y directions, respectively. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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11 pages, 4389 KiB

Open AccessArticle

Through-Holes Design for Ideal LiNbO₃ A1 Resonators

by Shu-Mao Wu, Chen-Bei Hao, Zhen-Hui Qin, Yong Wang, Hua-Yang Chen, Si-Yuan Yu and Yan-Feng Chen

Micromachines 2023, 14(7), 1341; https://doi.org/10.3390/mi14071341 - 30 Jun 2023

Cited by 2 | Viewed by 1200

Abstract

This paper proposes a method to realize ideal lithium niobate (LiNbO₃) A1 resonators. By introducing subwavelength through-holes between the interdigital transducer (IDT) electrodes on the LiNbO₃ surface, all unfavorable spurious modes of the resonators can be suppressed completely. It is [...] Read more.

This paper proposes a method to realize ideal lithium niobate (LiNbO₃) A1 resonators. By introducing subwavelength through-holes between the interdigital transducer (IDT) electrodes on the LiNbO₃ surface, all unfavorable spurious modes of the resonators can be suppressed completely. It is convenient and valid for various IDT electrode parameters and different LiNbO₃ thicknesses. Also, this method does not require additional device fabrication steps. At the same time, these through-holes can greatly reduce the suspended area of the LiNbO₃ thin film, thus significantly improving the design flexibility, compactness, mechanical stability, temperature stability, and power tolerance of the resonators (and subsequent filters). It is expected to become an important means to promote the practical application of LiNbO₃ A1 filters and even all Lamb waves filters. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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9 pages, 13440 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Design of an Intelligent MEMS Safety and Arming Device with a Condition Feedback Function

by Kexin Wang, Tengjiang Hu, Yulong Zhao, Wei Ren and Yifei Wang

Micromachines 2023, 14(6), 1130; https://doi.org/10.3390/mi14061130 - 27 May 2023

Cited by 1 | Viewed by 1373

Abstract

A safety and arming device with a condition feedback function has been designed in this article to improve the intelligence and safety of ignition devices. The device achieves active control and recoverability by virtue of four groups of bistable mechanisms which consist of [...] Read more.

A safety and arming device with a condition feedback function has been designed in this article to improve the intelligence and safety of ignition devices. The device achieves active control and recoverability by virtue of four groups of bistable mechanisms which consist of two electrothermal actuators to drive a semi-circular barrier and a pawl. According to a specific operation sequence, the barrier is engaged by the pawl at the safety or the arming position. The four groups of bistable mechanisms are connected in parallel, and the device detects the contact resistance generated by the engagement of the barrier and pawl by the voltage division of an external resistor to determine the parallel number of the mechanism and give feedback on the device’s condition. The pawl as a safety lock can restrain the in-plane deformation of the barrier in the safety condition to improve the safety function of the device. An igniter (a NiCr bridge foil covered with different thicknesses of Al/CuO films) and boron/potassium nitrate (B/KNO₃, BPN) are assembled on both sides of the S&A device to verify the safety of the barrier. The test results show that the S&A device with a safety lock can realize the safety and arming functions when the thickness of the Al/CuO film is set to 80 μm and 100 μm. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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14 pages, 4297 KiB

Open AccessArticle

Design and Fabrication of a High-Temperature SOI Pressure Sensor with Optimized Crossbeam Membrane

by Le Hao, Cun Li, Lukang Wang, Bing Bai, Yulong Zhao and Chao Luo

Micromachines 2023, 14(5), 1045; https://doi.org/10.3390/mi14051045 - 12 May 2023

Cited by 4 | Viewed by 1636

Abstract

This paper presents a SOI piezoresistive pressure sensor with the crossbeam membrane. The roots of the crossbeam were widened, which solved the problem of the poor dynamic performance of small-range pressure sensors working at a high temperature of 200 °C. A theoretical model [...] Read more.

This paper presents a SOI piezoresistive pressure sensor with the crossbeam membrane. The roots of the crossbeam were widened, which solved the problem of the poor dynamic performance of small-range pressure sensors working at a high temperature of 200 °C. A theoretical model was established to optimize the proposed structure, which combined the finite element and the curve fitting. Using the theoretical model, the structural dimensions were optimized to obtain the optimal sensitivity. During optimization, the sensor nonlinearity was also taken into consideration. The sensor chip was fabricated by MEMS bulk-micromachining technology, and Ti/Pt/Au metal leads were prepared to improve the sensor ability of high-temperature resistance over a long time. The sensor chip was packaged and tested, and the experimental results show the sensor achieved an accuracy of 0.241% FS, nonlinearity of 0.180% FS, hysteresis of 0.086% FS and repeatability of 0.137% FS at the high temperature. Given the good reliability and performance at the high temperature, the proposed sensor provides a suitable alternative for the measurement of pressure at high temperatures. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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13 pages, 3788 KiB

Open AccessArticle

Polymer Ring–Flexure–Membrane Suspended Gate FET Gas Sensor: Design, Modelling and Simulation

by Joel Zacharias, Pramod Martha and V. Seena

Micromachines 2023, 14(5), 944; https://doi.org/10.3390/mi14050944 - 26 Apr 2023

Viewed by 1613

Abstract

This work reports the design, modelling, and simulation of a novel polymer MEMS gas sensor platform called a ring–flexure–membrane (RFM) suspended gate field effect transistor (SGFET). The sensor consists of a suspended polymer (SU-8) MEMS based RFM structure holding the gate of the [...] Read more.

This work reports the design, modelling, and simulation of a novel polymer MEMS gas sensor platform called a ring–flexure–membrane (RFM) suspended gate field effect transistor (SGFET). The sensor consists of a suspended polymer (SU-8) MEMS based RFM structure holding the gate of the SGFET with the gas sensing layer on top of the outer ring. During gas adsorption, the polymer ring–flexure–membrane architecture ensures a constant gate capacitance change throughout the gate area of the SGFET. This leads to efficient transduction of the gas adsorption-induced nanomechanical motion input to the change in the output current of the SGFET, thus improving the sensitivity. The sensor performance has been evaluated for sensing hydrogen gas using the finite element method (FEM) and TCAD simulation tools. The MEMS design and simulation of the RFM structure is carried out using CoventorWare 10.3, and the design, modelling, and simulation of the SGFET array is carried out using the Synopsis Sentaurus TCAD. A differential amplifier circuit using RFM-SGFET is designed and simulated in Cadence Virtuoso using the lookup table (LUT) of the RFM-SGFET. The differential amplifier exhibits a sensitivity of 2.8 mV/MPa for a gate bias of 3 V and a maximum detection range of up to 1% hydrogen gas concentration. This work also presents a detailed fabrication process integration plan to realize the RFM-SGFET sensor using a tailored self-aligned CMOS process adopting the surface micromachining process. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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13 pages, 4858 KiB

Open AccessArticle

On the Investigation of Frequency Characteristics of a Novel Inductive Debris Sensor

by Xianwei Wu, Hairui Liu, Zhi Qian, Zhenghua Qian, Dianzi Liu, Kun Li and Guoshuai Wang

Micromachines 2023, 14(3), 669; https://doi.org/10.3390/mi14030669 - 17 Mar 2023

Cited by 2 | Viewed by 1044

Abstract

Lubricants have the ability to reduce frictions, prevent wear, convey metal debris particles and increase the efficiency of heat transfer; therefore, they have been widely used in mechanical systems. To assess the safety and reliability of the machine under operational conditions, the development [...] Read more.

Lubricants have the ability to reduce frictions, prevent wear, convey metal debris particles and increase the efficiency of heat transfer; therefore, they have been widely used in mechanical systems. To assess the safety and reliability of the machine under operational conditions, the development of inductive debris sensors for the online monitoring of debris particles in lubricants has received more attention from researchers. To achieve a high-precision, high-efficiency sensor for accurate prediction on the degree of wear, the equivalent circuit model of the sensor coil has been established, and its equations discovering the relationship between the induced voltage and excitation frequency have been derived. Furthermore, the influence of excitation frequencies and metal debris on the magnetic flux density has been analyzed throughout the simulations to determine the sensor magnetic field. In order to identify a frequency range suitable for detecting both ferrous and non-ferrous materials with a high level of sensitivity, the analytical analysis and experiments have been conducted to investigate the frequency characteristics of the developed inductive debris sensor prototype and its improved inspection capability. Moreover, the developed inductive debris sensor with the noticeable frequency characteristics has been assessed and its theoretical model has been also validated throughout experimental tests. Results have shown that the detection sensitivity of non-ferrous debris by the developed sensor increases with the excitation frequency in the range of 50 kHz to 250 kHz, while more complex results for the detection of ferrous debris have been observed. The detection sensitivity decreases as the excitation frequency increases from 50 kHz to 300 kHz, and then increases with the excitation frequency from 300 kHz to 370 kHz. This leads to the effective selection of the excitation frequency in the process of inspection. In summary, the investigation into the frequency characteristics of the proposed novel inductive debris sensor has enabled its broad applications and also provided a theoretical basis and valuable insights into the development of inductive debris sensors with improved detection sensitivity. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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13 pages, 4909 KiB

Open AccessArticle

Femtosecond Laser Processing Assisted SiC High-Temperature Pressure Sensor Fabrication and Performance Test

by You Zhao, Yulong Zhao, Lukang Wang, Yu Yang and Yabing Wang

Micromachines 2023, 14(3), 587; https://doi.org/10.3390/mi14030587 - 28 Feb 2023

Cited by 4 | Viewed by 1502

Abstract

Due to material plastic deformation and current leakage at high temperatures, SOI (silicon-on-insulator) and SOS (silicon-on-sapphire) pressure sensors have difficulty working over 500 °C. Silicon carbide (SiC) is a promising sensor material to solve this problem because of its stable mechanical and electrical [...] Read more.

Due to material plastic deformation and current leakage at high temperatures, SOI (silicon-on-insulator) and SOS (silicon-on-sapphire) pressure sensors have difficulty working over 500 °C. Silicon carbide (SiC) is a promising sensor material to solve this problem because of its stable mechanical and electrical properties at high temperatures. However, SiC is difficult to process which hinders its application as a high-temperature pressure sensor. This study proposes a piezoresistive SiC pressure sensor fabrication method to overcome the difficulties in SiC processing, especially deep etching. The sensor was processed by a combination of ICP (inductive coupled plasma) dry etching, high-temperature rapid annealing and femtosecond laser deep etching. Static and dynamic calibration tests show that the accuracy error of the fabricated sensor can reach 0.33%FS, and the dynamic signal response time is 1.2 μs. High and low temperature test results show that the developed sensor is able to work at temperatures from −50 °C to 600 °C, which demonstrates the feasibility of the proposed sensor fabrication method. Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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Review

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34 pages, 6074 KiB

Open AccessReview

A Review of Fingerprint Sensors: Mechanism, Characteristics, and Applications

by Yirong Yu, Qiming Niu, Xuyang Li, Jianshe Xue, Weiguo Liu and Dabin Lin

Micromachines 2023, 14(6), 1253; https://doi.org/10.3390/mi14061253 - 14 Jun 2023

Cited by 6 | Viewed by 7998

Abstract

Identification technology based on biometrics is a branch of research that employs the unique individual traits of humans to authenticate identity, which is the most secure method of identification based on its exceptional high dependability and stability of human biometrics. Common biometric identifiers [...] Read more.

Identification technology based on biometrics is a branch of research that employs the unique individual traits of humans to authenticate identity, which is the most secure method of identification based on its exceptional high dependability and stability of human biometrics. Common biometric identifiers include fingerprints, irises, and facial sounds, among others. In the realm of biometric recognition, fingerprint recognition has gained success with its convenient operation and fast identif ication speed. Different fingerprint collecting techniques, which supply fingerprint information for fingerprint identification systems, have attracted a significant deal of interest in authentication technology regarding fingerprint identification systems. This work presents several fingerprint acquisition techniques, such as optical capacitive and ultrasonic, and analyzes acquisition types and structures. In addition, the pros and drawbacks of various sensor types, as well as the limits and benefits of optical, capacitive, and ultrasonic kinds, are discussed. It is the necessary stage for the application of the Internet of Things (IoT). Full article

(This article belongs to the Special Issue MEMS/NEMS Sensors and Actuators, 2nd Edition)

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