MEMS Sensors and Resonators

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Applied Sciences applsci	2.5	5.3	2011	18.4 Days	CHF 2400
Electronics electronics	2.6	5.3	2012	16.4 Days	CHF 2400
Eng eng	-	2.1	2020	21.5 Days	CHF 1200
Micromachines micromachines	3.0	5.2	2010	16.2 Days	CHF 2100
Sensors sensors	3.4	7.3	2001	18.6 Days	CHF 2600

12 pages, 4635 KiB

Open AccessArticle

A High-Reliability RF MEMS Metal-Contact Switch Based on Al-Sc Alloy

by Zhongxuan Hou, Yongkang Zhang, Chaowei Si, Guowei Han, Yongmei Zhao, Xiaorui Lu, Jiahui Liu, Jin Ning and Tongbo Wei

Micromachines 2023, 14(6), 1098; https://doi.org/10.3390/mi14061098 - 23 May 2023

Cited by 5 | Viewed by 3932

Abstract

This paper presents a new metal-contact RF MEMS switch based on an Al-Sc alloy. The use of an Al-Sc alloy is intended to replace the traditional Au-Au contact, which can greatly improve the hardness of the contact, and thus improve the reliability of [...] Read more.

This paper presents a new metal-contact RF MEMS switch based on an Al-Sc alloy. The use of an Al-Sc alloy is intended to replace the traditional Au-Au contact, which can greatly improve the hardness of the contact, and thus improve the reliability of the switch. The multi-layer stack structure is adopted to achieve the low switch line resistance and hard contact surface. The polyimide sacrificial layer process is developed and optimized, and the RF switches are fabricated and tested for pull-in voltage, S-parameters, and switching time. The switch shows high isolation of more than 24 dB and a low insertion loss of less than 0.9 dB in the frequency range of 0.1–6 GHz. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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15 pages, 5711 KiB

Open AccessArticle

Wide Temperature Range and Low Temperature Drift Eddy Current Displacement Sensor Using Digital Correlation Demodulation

by Tianxiang Ma, Yuting Han, Yongsen Xu, Pengzhang Dai, Honghai Shen and Yunqing Liu

Sensors 2023, 23(10), 4895; https://doi.org/10.3390/s23104895 - 19 May 2023

Cited by 5 | Viewed by 2588

Abstract

Conventional eddy-current sensors have the advantages of being contactless and having high bandwidth and high sensitivity. They are widely used in micro-displacement measurement, micro-angle measurement, and rotational speed measurement. However, they are based on the principle of impedance measurement, so the influence of [...] Read more.

Conventional eddy-current sensors have the advantages of being contactless and having high bandwidth and high sensitivity. They are widely used in micro-displacement measurement, micro-angle measurement, and rotational speed measurement. However, they are based on the principle of impedance measurement, so the influence of temperature drift on sensor accuracy is difficult to overcome. A differential digital demodulation eddy current sensor system was designed to reduce the influence of temperature drift on the output accuracy of the eddy current sensor. The differential sensor probe was used to eliminate common-mode interference caused by temperature, and the differential analog carrier signal was digitized by a high-speed ADC. In the FPGA, the amplitude information is resolved using the double correlation demodulation method. The main sources of system errors were determined, and a test device was designed using a laser autocollimator. Tests were conducted to measure various aspects of sensor performance. Testing showed the following metrics for the differential digital demodulation eddy current sensor: nonlinearity 0.68% in the range of ±2.5 mm, resolution 760 nm, maximum bandwidth 25 kHz, and significant suppression in the temperature drift compared to analog demodulation methods. The tests show that the sensor has high precision, low temperature drift and great flexibility, and it can instead of conventional sensors in applications with large temperature variability. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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11 pages, 6329 KiB

Open AccessArticle

A Single-Side Micromachined MPa-Scale High-Temperature Pressure Sensor

by Peng Li, Wei Li, Changnan Chen, Sheng Wu, Pichao Pan, Ke Sun, Min Liu, Jiachou Wang and Xinxin Li

Micromachines 2023, 14(5), 981; https://doi.org/10.3390/mi14050981 - 29 Apr 2023

Cited by 3 | Viewed by 2420

Abstract

This paper proposes a piezoresistive high-temperature absolute pressure sensor based on (100)/(111) hybrid SOI (silicon-on-insulator) silicon wafers, where the active layer is (100) silicon and the handle layer is (111) silicon. The 1.5 MPa ranged sensor chips are designed with the size as [...] Read more.

This paper proposes a piezoresistive high-temperature absolute pressure sensor based on (100)/(111) hybrid SOI (silicon-on-insulator) silicon wafers, where the active layer is (100) silicon and the handle layer is (111) silicon. The 1.5 MPa ranged sensor chips are designed with the size as tiny as 0.5 × 0.5 mm, and the chips are fabricated only from the front side of the wafer for simple, high-yield and low-cost batch production. Herein, the (100) active layer is specifically used to form high-performance piezoresistors for high-temperature pressure sensing, while the (111) handle layer is used to single-side construct the pressure-sensing diaphragm and the pressure-reference cavity beneath the diaphragm. Benefitting from front-sided shallow dry etching and self-stop lateral wet etching inside the (111)-silicon substrate, the thickness of the pressure-sensing diaphragm is uniform and controllable, and the pressure-reference cavity is embedded into the handle layer of (111) silicon. Without the conventionally used double-sided etching, wafer bonding and cavity-SOI manufacturing, a very small sensor chip size of 0.5 × 0.5 mm is achieved. The measured performance of the 1.5 MPa ranged pressure sensor exhibits a full-scale output of approximately 59.55 mV/1500 kPa/3.3 VDC in room temperature and a high overall accuracy (combined with hysteresis, non-linearity and repeatability) of 0.17%FS within the temperature range of −55 °C to 350 °C. In addition, the thermal hysteresis is also evaluated as approximately 0.15%FS at 350 °C. The tiny-sized high temperature pressure sensors are promising in various industrial automatic control applications and wind tunnel testing systems. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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14 pages, 4413 KiB

Open AccessArticle

An In-Situ Tester for Extracting Piezoresistive Coefficients

by Fengyang Li, Runze Yu and Dacheng Zhang

Micromachines 2023, 14(4), 885; https://doi.org/10.3390/mi14040885 - 20 Apr 2023

Viewed by 1792

Abstract

In this study, an electrostatic force-driven on-chip tester consisting of a mass with four guided cantilever beams was employed to extract the process-related bending stiffness and piezoresistive coefficient in-situ for the first time. The tester was manufactured using the standard bulk silicon piezoresistance [...] Read more.

In this study, an electrostatic force-driven on-chip tester consisting of a mass with four guided cantilever beams was employed to extract the process-related bending stiffness and piezoresistive coefficient in-situ for the first time. The tester was manufactured using the standard bulk silicon piezoresistance process of Peking University, and was tested on-chip without additional handling. In order to reduce the deviation from process effects, the process-related bending stiffness was first extracted as an intermediate value, namely, 3590.74 N/m, which is 1.66% lower than the theoretical value. Then, the value was used to extract the piezoresistive coefficient using a finite element method (FEM) simulation. The extracted piezoresistive coefficient was 9.851 × 10⁻¹⁰ Pa⁻¹, which essentially matched the average piezoresistive coefficient of the computational model based on the doping profile we first proposed. Compared with traditional extraction methods, such as the four-point bending method, this test method is on-chip, achieving automatic loading and precise control of the driving force, so it has high reliability and repeatability. Because the tester is manufactured together with the MEMS device, it has the potential to be used for process quality evaluation and monitoring on MEMS sensor production lines. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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13 pages, 6366 KiB

Open AccessArticle

A GHz Silicon-Based Width Extensional Mode MEMS Resonator with Q over 10,000

by Wenli Liu, Yujie Lu, Zeji Chen, Qianqian Jia, Junyuan Zhao, Bo Niu, Wei Wang, Yalu Hao, Yinfang Zhu, Jinling Yang and Fuhua Yang

Sensors 2023, 23(8), 3808; https://doi.org/10.3390/s23083808 - 7 Apr 2023

Cited by 7 | Viewed by 2645

Abstract

This work presents a silicon-based capacitively transduced width extensional mode (WEM) MEMS rectangular plate resonator with quality factor (Q) of over 10,000 at a frequency of greater than 1 GHz. The Q value, determined by various loss mechanisms, was analyzed and [...] Read more.

This work presents a silicon-based capacitively transduced width extensional mode (WEM) MEMS rectangular plate resonator with quality factor (Q) of over 10,000 at a frequency of greater than 1 GHz. The Q value, determined by various loss mechanisms, was analyzed and quantified via numerical calculation and simulation. The energy loss of high order WEMs is dominated by anchor loss and phonon-phonon interaction dissipation (PPID). High-order resonators possess high effective stiffness, resulting in large motional impedance. To suppress anchor loss and reduce motional impedance, a novel combined tether was designed and comprehensively optimized. The resonators were batch fabricated based on a reliable and simple silicon-on-insulator (SOI)-based fabrication process. The combined tether experimentally contributes to low anchor loss and motional impedance. Especially in the 4th WEM, the resonator with a resonance frequency of 1.1 GHz and a Q of 10,920 was demonstrated, corresponding to the promising f × Q product of 1.2 × 10¹³. By using combined tether, the motional impedance decreases by 33% and 20% in 3rd and 4th modes, respectively. The WEM resonator proposed in this work has potential application for high-frequency wireless communication systems. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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11 pages, 15821 KiB

Open AccessArticle

Detection of In-Plane Movement in Electrically Actuated Microelectromechanical Systems Using a Scanning Electron Microscope

by Tarmo Nieminen, Nikhilendu Tiwary, Glenn Ross and Mervi Paulasto-Kröckel

Micromachines 2023, 14(3), 698; https://doi.org/10.3390/mi14030698 - 22 Mar 2023

Cited by 3 | Viewed by 2362

Abstract

The measurement of in-plane motion in microelectromechanical systems (MEMS) is a challenge for existing measurement techniques due to the small size of the moving devices and the low amplitude of motion. This paper studied the possibility of using images obtained using a scanning [...] Read more.

The measurement of in-plane motion in microelectromechanical systems (MEMS) is a challenge for existing measurement techniques due to the small size of the moving devices and the low amplitude of motion. This paper studied the possibility of using images obtained using a scanning electron microscope (SEM) together with existing motion detection algorithms to characterize the motion of MEMS. SEM imaging has previously been used to detect motion in MEMS device. However, the differences in how SEM imaging and optical imaging capture motion, together with possible interference caused by electrical actuation, create doubts about how accurately motion could be detected in a SEM. In this work, it is shown that existing motion detection algorithms can be used to detect movement with an amplitude of 69 nm. In addition, the properties of SEM images, such as bright edges, complement these algorithms. Electrical actuation was found to cause error in the measurement, however, the error was limited to regions that were electrically connected to the actuating probes and minimal error could be detected in regions that were electrically insulated from the probes. These results show that an SEM is a powerful tool for characterizing low amplitude motion and electrical contacts in MEMS and allow for the detection of motion under 100 nm in amplitude. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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15 pages, 5288 KiB

Open AccessArticle

Stiffness Considerations for a MEMS-Based Weighing Cell

by Karin Wedrich, Valeriya Cherkasova, Vivien Platl, Thomas Fröhlich and Steffen Strehle

Sensors 2023, 23(6), 3342; https://doi.org/10.3390/s23063342 - 22 Mar 2023

Cited by 7 | Viewed by 2290

Abstract

In this paper, a miniaturized weighing cell that is based on a micro-electro-mechanical-system (MEMS) is discussed. The MEMS-based weighing cell is inspired by macroscopic electromagnetic force compensation (EMFC) weighing cells and one of the crucial system parameters, the stiffness, is analyzed. The system [...] Read more.

In this paper, a miniaturized weighing cell that is based on a micro-electro-mechanical-system (MEMS) is discussed. The MEMS-based weighing cell is inspired by macroscopic electromagnetic force compensation (EMFC) weighing cells and one of the crucial system parameters, the stiffness, is analyzed. The system stiffness in the direction of motion is first analytically evaluated using a rigid body approach and then also numerically modeled using the finite element method for comparison purposes. First prototypes of MEMS-based weighing cells were successfully microfabricated and the occurring fabrication-based system characteristics were considered in the overall system evaluation. The stiffness of the MEMS-based weighing cells was experimentally determined by using a static approach based on force-displacement measurements. Considering the geometry parameters of the microfabricated weighing cells, the measured stiffness values fit to the calculated stiffness values with a deviation from −6.7 to 3.8% depending on the microsystem under test. Based on our results, we demonstrate that MEMS-based weighing cells can be successfully fabricated with the proposed process and in principle be used for high-precision force measurements in the future. Nevertheless, improved system designs and read-out strategies are still required. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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18 pages, 3772 KiB

Open AccessArticle

Study of the Performance Enhancement of Sc-Doped AlN Super High Frequency Cross-Sectional Lamé Mode Resonators

by Meruyert Assylbekova, Michele Pirro, Xuanyi Zhao, Giuseppe Michetti, Pietro Simeoni and Matteo Rinaldi

Micromachines 2023, 14(3), 515; https://doi.org/10.3390/mi14030515 - 23 Feb 2023

Cited by 8 | Viewed by 2706

Abstract

The increasing use of mobile broadband requires new acoustic filtering technologies that can operate efficiently at frequencies above 6 GHz. Previous research has shown that AlN Super High Frequency (SHF) Cross-Sectional Lamé Mode resonators (CLMRs) can address this challenge, but their performance is [...] Read more.

The increasing use of mobile broadband requires new acoustic filtering technologies that can operate efficiently at frequencies above 6 GHz. Previous research has shown that AlN Super High Frequency (SHF) Cross-Sectional Lamé Mode resonators (CLMRs) can address this challenge, but their performance is limited by the piezoelectric strength of AlN. In this work, we explore the use of substitutional doping of Al in AlN with Sc to enhance the

k_{t}^{2}

values of SHF CLMRs. Our results showed that the measured

k_{t}^{2}

·

Q_{m}

product of Al

_{72}

Sc

_{28}

N CLMRs was four times greater than that of AlN CLMRs operating at the same frequency. Additionally, the measured fractional bandwidth (FWB) of Al

_{72}

Sc

_{28}

N 2nd order ladder filters was 4.13%, a fourfold improvement over AlN filters with the same design. We also discuss other aspects of the technology, such as power handling, losses, and spurious mode suppression, and identify potential areas for future research. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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17 pages, 5571 KiB

Open AccessArticle

Boosting the Electrostatic MEMS Converter Output Power by Applying Three Effective Performance-Enhancing Techniques

by Mona S. Salem, Abdelhalim Zekry, Mohamed Abouelatta, Ahmed Shaker, Marwa S. Salem, Christian Gontrand and Ahmed Saeed

Micromachines 2023, 14(2), 485; https://doi.org/10.3390/mi14020485 - 19 Feb 2023

Cited by 2 | Viewed by 2044

Abstract

This current study aims to enhance the electrostatic MEMS converter performance mainly by boosting its output power. Three different techniques are applied to accomplish such performance enhancement. Firstly, the power is boosted by scaling up the technology of the converter CMOS accompanied circuit, [...] Read more.

This current study aims to enhance the electrostatic MEMS converter performance mainly by boosting its output power. Three different techniques are applied to accomplish such performance enhancement. Firstly, the power is boosted by scaling up the technology of the converter CMOS accompanied circuit, the power conditioning, and power controlling circuits, from 0.35 µm to 0.6 µm CMOS technology. As the converter area is in the range of mm², there are no restrictions concerning the scaling up of the accompanied converter CMOS circuits. As a result, the maximum voltage of the system for harvesting energy, V_max, which is the most effective system constraint that greatly affects the converter’s output power, increases from 8 V to 30 V. The output power of the designed and simulated converter based on the 0.6 µm technology increases from 2.1 mW to 4.5 mW. Secondly, the converter power increases by optimizing its technological parameters, the converter thickness and the converter finger width and length. Such optimization causes the converter output power to increase from 4.5 mW to 11.2 mW. Finally, the converter structure is optimized to maximize its finger length by using its wasted shuttle mass area which does not contribute to its capacitances and output power. The proposed structure increases the converter output power from 11.2 mW to 14.29 mW. Thus, the three applied performance enhancement techniques boosted the converter output power by 12.19 mW, which is a considerable enhancement in the converter performance. All simulations are carried out using COMSOL Multiphysics 5.4. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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9 pages, 2994 KiB

Open AccessArticle

An All-Silicon Resonant Pressure Microsensor Based on Eutectic Bonding

by Siyuan Chen, Jiaxin Qin, Yulan Lu, Bo Xie, Junbo Wang, Deyong Chen and Jian Chen

Micromachines 2023, 14(2), 441; https://doi.org/10.3390/mi14020441 - 13 Feb 2023

Cited by 7 | Viewed by 2214

Abstract

In this paper, an all-Si resonant pressure microsensor based on eutectic bonding was developed, which can eliminate thermal expansion coefficient mismatches and residual thermal stresses during the bonding process. More specifically, the resonant pressure microsensor included an SOI wafer with a pressure-sensitive film [...] Read more.

In this paper, an all-Si resonant pressure microsensor based on eutectic bonding was developed, which can eliminate thermal expansion coefficient mismatches and residual thermal stresses during the bonding process. More specifically, the resonant pressure microsensor included an SOI wafer with a pressure-sensitive film embedded with resonators, which was eutectically bonded with a silicon cap for vacuum encapsulation. The all-Si resonant pressure microsensor was carefully designed and simulated numerically, where the use of the silicon cap was shown to effectively address temperature disturbances of the microsensor. The microsensor was then fabricated based on MEMS processes where eutectic bonding was adopted to link the SOI wafer and the silicon cap. The characterization results showed that the temperature disturbances of the resonant pressure microsensor encapsulated with the silicon cap were quantified as −0.82 Hz/°C of the central resonator and −2.36 Hz/°C of the side resonator within a temperature range from −40 °C to 80 °C, which were at least eight times lower than that of the microsensor encapsulated with the glass cap. Compared with the microsensor using the glass cap, the all-silicon microsensor demonstrated an accuracy improvement from 0.03% FS to 0.01% FS and a reduction in short-term frequency fluctuations from 3.2 Hz to 1.5 Hz. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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25 pages, 9226 KiB

Open AccessReview

Concepts and Key Technologies of Microelectromechanical Systems Resonators

by Tianren Feng, Quan Yuan, Duli Yu, Bo Wu and Hui Wang

Micromachines 2022, 13(12), 2195; https://doi.org/10.3390/mi13122195 - 11 Dec 2022

Cited by 14 | Viewed by 5221

Abstract

In this paper, the basic concepts of the equivalent model, vibration modes, and conduction mechanisms of MEMS resonators are described. By reviewing the existing representative results, the performance parameters and key technologies, such as quality factor, frequency accuracy, and temperature stability of MEMS [...] Read more.

In this paper, the basic concepts of the equivalent model, vibration modes, and conduction mechanisms of MEMS resonators are described. By reviewing the existing representative results, the performance parameters and key technologies, such as quality factor, frequency accuracy, and temperature stability of MEMS resonators, are summarized. Finally, the development status, existing challenges and future trend of MEMS resonators are summarized. As a typical research field of vibration engineering, MEMS resonators have shown great potential to replace quartz resonators in timing, frequency, and resonant sensor applications. However, because of the limitations of practical applications, there are still many aspects of the MEMS resonators that could be improved. This paper aims to provide scientific and technical support for the improvement of MEMS resonators in timing, frequency, and resonant sensor applications. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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12 pages, 2765 KiB

Open AccessArticle

Fabrication of Vertical MEMS Actuator with Hollow Square Electrode for SPR Sensing Applications

by Kihyun Kim, Yeonsu Lee, Ignacio Llamas-Garro and Jung-Mu Kim

Sensors 2022, 22(23), 9490; https://doi.org/10.3390/s22239490 - 5 Dec 2022

Cited by 1 | Viewed by 2538

Abstract

In this study, an electrostatically driven vertical MEMS actuator was designed using a hollow square electrode. To attain vertical actuation, a hollow square-shaped electrode was designed on the glass substrate. The silicon proof mass, containing a step, was utilized to realize analogue actuation [...] Read more.

In this study, an electrostatically driven vertical MEMS actuator was designed using a hollow square electrode. To attain vertical actuation, a hollow square-shaped electrode was designed on the glass substrate. The silicon proof mass, containing a step, was utilized to realize analogue actuation without pull-in. The vertical MEMS actuator was fabricated using the SiOG (Silicon on Glass) process and the total actuator size was 8.3 mm × 8.3 mm. The fabricated proof mass was freestanding due to eight serpentine springs with 30 μm width. The vertical movement of the MEMS actuator was successfully controlled electrostatically. The measured vertical movement was 5.6 µm for a voltage of 40 V, applied between the top silicon structure and the hollow square electrode. The results shown here confirm that the proposed MEMS actuator was able to control the vertical displacement using an applied voltage. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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8 pages, 1852 KiB

Open AccessArticle

Thermal-Resistance Effect of Graphene at High Temperatures in Nanoelectromechanical Temperature Sensors

by Shuai Lei, Ningning Su and Mengwei Li

Micromachines 2022, 13(12), 2078; https://doi.org/10.3390/mi13122078 - 26 Nov 2022

Cited by 12 | Viewed by 2925

Abstract

Graphene membranes act as temperature sensors in nanoelectromechanical devices due to their excellent thermal and high-temperature resistance properties. Experimentally, reports on the sensing performance of graphene mainly focus on the temperature interval under 400 K. To explore the sensing performance of graphene temperature [...] Read more.

Graphene membranes act as temperature sensors in nanoelectromechanical devices due to their excellent thermal and high-temperature resistance properties. Experimentally, reports on the sensing performance of graphene mainly focus on the temperature interval under 400 K. To explore the sensing performance of graphene temperature sensors at higher temperature intervals, micro-fabricated single-layer graphene on a SiN_X substrate is presented as temperature sensors by semiconductor technology and its electrical properties were measured. The results show that the temperature coefficient of the resistance value is 2.07 × 10⁻³ in the temperature range of 300–450 K and 2.39 × 10⁻³ in the temperature range of 450–575 K. From room temperature to high temperature, the “metal” characteristics are presented, and the higher TCR obtained at higher temperature interval is described and analyzed by combining Boltzmann transport equation and thermal expansion theory. These investigations provide further insight into the temperature characteristics of graphene. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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14 pages, 5599 KiB

Open AccessArticle

A Novel Packaged Ultra-High Q Silicon MEMS Butterfly Vibratory Gyroscope

by Lu Jia, Guowei Han, Zhenyu Wei, Chaowei Si, Jin Ning, Fuhua Yang and Weihua Han

Micromachines 2022, 13(11), 1967; https://doi.org/10.3390/mi13111967 - 13 Nov 2022

Cited by 3 | Viewed by 2605

Abstract

A novel three-dimensional (3D) wafer-level sandwich packaging technology is here applied in the dual mass MEMS butterfly vibratory gyroscope (BFVG) to achieve ultra-high Q factor. A GIS (glass in silicon) composite substrate with glass as the main body and low-resistance silicon column as [...] Read more.

A novel three-dimensional (3D) wafer-level sandwich packaging technology is here applied in the dual mass MEMS butterfly vibratory gyroscope (BFVG) to achieve ultra-high Q factor. A GIS (glass in silicon) composite substrate with glass as the main body and low-resistance silicon column as the vertical lead is processed by glass reflow technology, which effectively avoids air leakage caused by thermal stress mismatch. Sputter getter material is used on the glass cap to further improve the vacuum degree. The Silicon-On-Insulator (SOI) gyroscope structure is sandwiched between the composite substrate and glass cap to realize vertical electrical interconnection by high-vacuum anodic bonding. The Q factors of drive and sense modes in BFVG measured by the self-developed double closed-loop circuit system are significantly improved to 8.628 times and 2.779 times higher than those of the traditional ceramic shell package. The experimental results of the processed gyroscope also demonstrate a high resolution of 0.1°/s, the scale factor of 1.302 mV/(°/s), and nonlinearity of 558 ppm in the full-scale range of ±1800°/s. By calculating the Allen variance, we obtained the angular random walk (ARW) of 1.281°/√h and low bias instability (BI) of 9.789°/h. The process error makes the actual drive and sense frequency of the gyroscope deviate by 8.989% and 5.367% compared with the simulation. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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36 pages, 8024 KiB

Open AccessReview

A Review of MEMS Vibrating Gyroscopes and Their Reliability Issues in Harsh Environments

by Waqas Amin Gill, Ian Howard, Ilyas Mazhar and Kristoffer McKee

Sensors 2022, 22(19), 7405; https://doi.org/10.3390/s22197405 - 29 Sep 2022

Cited by 48 | Viewed by 21567

Abstract

Micro-electromechanical systems (MEMS) vibrating gyroscopes have gained a lot of attention over the last two decades because of their low power consumption, easy integration, and low fabrication cost. The usage of the gyroscope equipped with an inertial measurement unit has increased tremendously, with [...] Read more.

Micro-electromechanical systems (MEMS) vibrating gyroscopes have gained a lot of attention over the last two decades because of their low power consumption, easy integration, and low fabrication cost. The usage of the gyroscope equipped with an inertial measurement unit has increased tremendously, with applications ranging from household devices to smart electronics to military equipment. However, reliability issues are still a concern when operating this inertial sensor in harsh environments, such as to control the movement and alignment of mini-satellites in space, tracking firefighters at an elevated temperature, and assisting aircraft navigation in gusty turbulent air. This review paper focuses on the key fundamentals of the MEMS vibrating gyroscopes, first discussing popular designs including the tuning fork, gimbal, vibrating ring, and multi-axis gyroscopes. It further investigates how bias stability, angle random walk, scale factor, and other performance parameters are affected in harsh environments and then discusses the reliability issues of the gyroscopes. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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14 pages, 2920 KiB

Open AccessArticle

Liquid Metal-Based Flexible and Wearable Sensor for Functional Human–Machine Interface

by Ye Tao, Feiyang Han, Changrui Shi, Ruizhe Yang, Yixing Chen and Yukun Ren

Micromachines 2022, 13(9), 1429; https://doi.org/10.3390/mi13091429 - 29 Aug 2022

Cited by 10 | Viewed by 3848

Abstract

Rigid sensors are a mature type of sensor, but their poor deformation and flexibility limit their application range. The appearance and development of flexible sensors provide an opportunity to solve this problem. In this paper, a resistive flexible sensor utilizes gallium−based liquid metal [...] Read more.

Rigid sensors are a mature type of sensor, but their poor deformation and flexibility limit their application range. The appearance and development of flexible sensors provide an opportunity to solve this problem. In this paper, a resistive flexible sensor utilizes gallium−based liquid metal (eutectic gallium indium alloy, EGaIn) and poly(dimethylsiloxane) (PDMS) and is fabricated using an injecting thin−line patterning technique based on soft lithography. Combining the scalable fabrication process and unique wire−shaped liquid metal design enables sensitive multifunctional measurement under stretching and bending loads. Furthermore, the flexible sensor is combined with the glove to demonstrate the application of the wearable sensor glove in the detection of finger joint angle and gesture control, which offers the ability of integration and multifunctional sensing of all−soft wearable physical microsystems for human–machine interfaces. It shows its application potential in medical rehabilitation, intelligent control, and so on. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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12 pages, 6959 KiB

Open AccessCommunication

A Study on the Design of Isolator and the Mounting Method for Reducing the Pyro-Shock of a MEMS IMU

by Kyungdon Ryu, ByungSu Park, Hyungsub Lee, Kyungjun Han and Sangwoo Lee

Sensors 2022, 22(13), 5037; https://doi.org/10.3390/s22135037 - 4 Jul 2022

Cited by 1 | Viewed by 4498

Abstract

In this paper, we proposed two methods for reducing the pyro-shock of the MEMS Inertial Measurement Unit (IMU). First, we designed the vibration isolator for reducing the pyro-shock inside the IMU. However, it turned out that there is a limit to reducing the [...] Read more.

In this paper, we proposed two methods for reducing the pyro-shock of the MEMS Inertial Measurement Unit (IMU). First, we designed the vibration isolator for reducing the pyro-shock inside the IMU. However, it turned out that there is a limit to reducing the pyro-shock with only the vibration isolator. Therefore, we improved the pyro-shock reduction performance by changing the method of mounting on the flight vehicle. Four mounting options were tested and one of them was adopted. The results showed the best reduction performance when we designed the vibration isolator with an aluminum integrated structure. When mounting, two methods were applied. One was to insert a bracket with a different material between the mounting surface and IMU and the other was to insert a set of three washers that was stacked in a PEEK-metal-PEEK order at each part of the screw connections. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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11 pages, 3377 KiB

Open AccessArticle

Novel Surface Acoustic Wave Temperature–Strain Sensor Based on LiNbO₃ for Structural Health Monitoring

by Xiangrong Li, Qiulin Tan, Li Qin, Xiawen Yan and Xiaorui Liang

Micromachines 2022, 13(6), 912; https://doi.org/10.3390/mi13060912 - 9 Jun 2022

Cited by 12 | Viewed by 2781

Abstract

In this paper, we present the design of an integrated temperature and strain dual-parameter sensor based on surface acoustic waves (SAWs). First, the COMSOL Multiphysics simulation software is used to determine separate frequencies for multiple sensors to avoid interference from their frequency offsets [...] Read more.

In this paper, we present the design of an integrated temperature and strain dual-parameter sensor based on surface acoustic waves (SAWs). First, the COMSOL Multiphysics simulation software is used to determine separate frequencies for multiple sensors to avoid interference from their frequency offsets caused by external physical quantity changes. The sensor consists of two parts, a temperature-sensitive unit and strain-sensitive unit, with frequencies of 94.97 MHz and 90.05 MHz, respectively. We use standard photolithography and ion beam etching technology to fabricate the SAW temperature–strain dual-parameter sensor. The sensing performance is tested in the ranges 0–250 °C and 0–700 μԑ. The temperature sensor monitors the ambient temperature in real time, and the strain sensor detects both strain and temperature. By testing the response of the strain sensor at different temperatures, the strain and temperature are decoupled through the polynomial fitting of the intercept and slope. The relationship between the strain and the frequency of the strain-sensitive unit is linear, the linear correlation is 0.98842, and the sensitivity is 100 Hz/μԑ at room temperature in the range of 0–700 μԑ. The relationship between the temperature and the frequency of the temperature-sensitive unit is linear, the linearity of the fitting curve is 0.99716, and the sensitivity is 7.62 kHz/°C in the range of 25–250 °C. This sensor has potential for use in closed environments such as natural gas or oil pipelines. Full article

(This article belongs to the Topic MEMS Sensors and Resonators)

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