Special Issue "MEMS Accelerometers"

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "A:Physics".

Deadline for manuscript submissions: closed (31 July 2018).

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A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Mahmoud Rasras
E-Mail Website
Guest Editor
Electrical and Computer Engineering, New York University, Abu Dhabi 129188, United Arab Emirates
Interests: photonics; optoelectronics; broadband circuits; sensors; opto-MEMS
Prof. Ibrahim (Abe) M. Elfadel
E-Mail Website
Guest Editor
Department of Electrical and Computer Engineering, Masdar Institute, Khalifa University of Science and Technology, Abu Dhabi, UAE
Interests: nano-scale integrated circuits and systems; MEMS-CMOS co-design; sensor array processing; micro power sources; photonics CAD
Prof. Dr. Ha Duong Ngo
E-Mail Website
Guest Editor
Hochschule für Technik und Wirtschaft Berlin, University of Applied Sciences, Treskowallee 8, 10318 Berlin, Germany
Interests: microsystems; piezoresistive sensor; sensor for harsh environments; SOI and SiC-based sensor; accelerometers; gas sensor; design and simulation of microsystems; graphene; material research; graphene-based sensors; biosensors; printed sensors; 2D sensors; technologies
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Special Issue Information

Dear Colleagues,

Micro-Electro-Mechanical Systems (MEMS) devices are widely used for inertia, pressure, and ultrasound sensing applications. Research on integrated MEMS technology has undergone extensive development driven by the requirement of compact footprint, low cost, and increased functionality. Accelerometers are among the most widely used sensors implemented in MEMS technology. MEMS Accelerometers are showing a growing presence in almost all industries ranging from automotive to medical. A traditional MEMS Accelerometer employs a proof mass suspended to springs, which displaces in response to an external acceleration.  A single proof mass can be used for one- or multi-axis sensing. A variety of transduction mechanisms have been used to detect the displacement. They include: capacitive, piezoelectric, thermal, tunneling, and optical. Capacitive accelerometers are widely used due to their DC measurement interface, thermal stability, reliability, and low-cost. However, they are sensitive to electromagnetic field interferences and have poor performance for high-end applications (e.g., precise attitude control for the satellite). Over the past three decades, steady progress has been made in the area of optical accelerometers for high-performance and high-sensitivity applications but several challenges are still to be tackled by researchers and engineers to fully realize Opto-Mechanical Accelerometers, such as chip-scale integration, scaling, low bandwidth, etc.

This Special Issue on "MEMS Accelerometers" seeks to highlight research papers, short communications, and review articles that focus on:

  1. Novel designs, fabrication platform, characterization, optimization, and modeling of MEMS accelerometers.
  2. Alternative transduction techniques with special emphasis on opto-mechanical sensing.
  3. Novel applications employing MEMS Accelerometers for consumer electronics, industries, medicine, entertainment, and navigation, etc.
  4. Multi-physics design tools and methodologies, including MEMS-electronics co-design.
  5. Novel accelerometer technologies and 9DoF IMU integration.
  6. Multi-accelerometer platforms and their data fusion.

Prof. Mahmoud Rasras
Prof. Ibrahim (Abe) M. Elfadel
Prof. Dr. Ha Duong Ngo
Guest Editors

Manuscript Submission Information

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Keywords

  • Inertial sensors
  • MEMS accelerometers
  • Optical accelerometers
  • Novel Fabrication Platforms
  • Micromachining
  • Multi-axis Accelerometers
  • MEMS accelerometer applications
  • MEMS accelerometer multi-physics modeling

Published Papers (17 papers)

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Editorial

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Editorial
Editorial for the Special Issue on MEMS Accelerometers
Micromachines 2019, 10(5), 290; https://doi.org/10.3390/mi10050290 - 29 Apr 2019
Viewed by 949
Abstract
Micro-Electro-Mechanical Systems (MEMS) devices are widely used for motion, pressure, light, and ultrasound sensing applications [...] Full article
(This article belongs to the Special Issue MEMS Accelerometers)

Research

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Article
Fabrication and Characteristics of a SOI Three-Axis Acceleration Sensor Based on MEMS Technology
Micromachines 2019, 10(4), 238; https://doi.org/10.3390/mi10040238 - 09 Apr 2019
Cited by 7 | Viewed by 1330
Abstract
A silicon-on-insulator (SOI) piezoresistive three-axis acceleration sensor, consisting of four L-shaped beams, two intermediate double beams, two masses, and twelve piezoresistors, was presented in this work. To detect the acceleration vector (ax, ay, and az) along [...] Read more.
A silicon-on-insulator (SOI) piezoresistive three-axis acceleration sensor, consisting of four L-shaped beams, two intermediate double beams, two masses, and twelve piezoresistors, was presented in this work. To detect the acceleration vector (ax, ay, and az) along three directions, twelve piezoresistors were designed on four L-shaped beams and two intermediate beams to form three detecting Wheatstone bridges. A sensitive element simulation model was built using ANSYS finite element simulation software to investigate the cross-interference of sensitivity for the proposed sensor. Based on that, the sensor chip was fabricated on a SOI wafer by using microelectromechanical system (MEMS) technology and packaged on a printed circuit board (PCB). At room temperature and VDD = 5.0 V, the sensitivities of the sensor along x-axis, y-axis, and z-axis were 0.255 mV/g, 0.131 mV/g, and 0.404 mV/g, respectively. The experimental results show that the proposed sensor can realize the detection of acceleration along three directions. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Analysis of Kerr Noise in Angular-Rate Sensing Based on Mode Splitting in a Whispering-Gallery-Mode Microresonator
Micromachines 2019, 10(2), 150; https://doi.org/10.3390/mi10020150 - 23 Feb 2019
Cited by 2 | Viewed by 1266
Abstract
Whispering-gallery-mode (WGM) microresonators have shown their potential in high-precision gyroscopes because of their small volume and high-quality factors. However, Kerr noise can always be the limit of accuracy. Angular-rate sensing based on mode splitting treats backscattering as a measured signal, which can induce [...] Read more.
Whispering-gallery-mode (WGM) microresonators have shown their potential in high-precision gyroscopes because of their small volume and high-quality factors. However, Kerr noise can always be the limit of accuracy. Angular-rate sensing based on mode splitting treats backscattering as a measured signal, which can induce mode splitting, while it is considered as a main source of noise in conventional resonator optical gyroscopes. Meanwhile, mode splitting also provides superior noise suppression owing to its self-reference scheme. Kerr noise in this scheme has not been defined and solved yet. Here, the mechanism of the Kerr noise in the measurement is analyzed and the mathematical expressions are derived, indicating the relationship between the Kerr noise and the output of the system. The influence caused by Kerr noise on the output is simulated and discussed. Simulations show that the deviation of the splitting caused by Kerr noise is 1.913 × 10−5 Hz at an angular rate of 5 × 106 °/s and the corresponding deviation of the angular rate is 9.26 × 10−9 °/s. It has been proven that angular-rate sensing based on mode splitting offers good suppression of Kerr noise. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
A Novel Fault-Tolerant Navigation and Positioning Method with Stereo-Camera/Micro Electro Mechanical Systems Inertial Measurement Unit (MEMS-IMU) in Hostile Environment
Micromachines 2018, 9(12), 626; https://doi.org/10.3390/mi9120626 - 27 Nov 2018
Cited by 6 | Viewed by 1634
Abstract
Visual odometry (VO) is a new navigation and positioning method that estimates the ego-motion of vehicles from images. However, VO with unsatisfactory performance can fail severely in hostile environment because of the less feature, fast angular motions, or illumination change. Thus, enhancing the [...] Read more.
Visual odometry (VO) is a new navigation and positioning method that estimates the ego-motion of vehicles from images. However, VO with unsatisfactory performance can fail severely in hostile environment because of the less feature, fast angular motions, or illumination change. Thus, enhancing the robustness of VO in hostile environment has become a popular research topic. In this paper, a novel fault-tolerant visual-inertial odometry (VIO) navigation and positioning method framework is presented. The micro electro mechanical systems inertial measurement unit (MEMS-IMU) is used to aid the stereo-camera, for a robust pose estimation in hostile environment. In the algorithm, the MEMS-IMU pre-integration is deployed to improve the motion estimation accuracy and robustness in the cases of similar or few feature points. Besides, a dramatic change detector and an adaptive observation noise factor are introduced, tolerating and decreasing the estimation error that is caused by large angular motion or wrong matching. Experiments in hostile environment showing that the presented method can achieve better position estimation when compared with the traditional VO and VIO method. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Design and Analysis of the Elastic-Beam Delaying Mechanism in a Micro-Electro-Mechanical Systems Device
Micromachines 2018, 9(11), 567; https://doi.org/10.3390/mi9110567 - 02 Nov 2018
Cited by 8 | Viewed by 1549
Abstract
The delaying mechanism is an important part of micro-electro-mechanical systems (MEMS) devices. However, very few mechanical delaying mechanisms are available. In this paper, an elastic-beam delaying mechanism has been proposed innovatively through establishing a three-dimensional model of an elastic-beam delay mechanism, establishing the [...] Read more.
The delaying mechanism is an important part of micro-electro-mechanical systems (MEMS) devices. However, very few mechanical delaying mechanisms are available. In this paper, an elastic-beam delaying mechanism has been proposed innovatively through establishing a three-dimensional model of an elastic-beam delay mechanism, establishing the force and the parameters of an elastic-beam delay mechanism, deriving the mathematical model according to the rigid dynamic mechanics theory, establishing the finite element model by using Ls-dyna solver of the Ansys software, and carrying out the centrifugal test. Simulation and test results match theoretical results quite well. It is believed that the elastic-beam delaying mechanism is quite effective and useful to slow the speed of the movable part in MEMS devices. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
A Novel, Hybrid-Integrated, High-Precision, Vacuum Microelectronic Accelerometer with Nano-Field Emission Tips
Micromachines 2018, 9(10), 481; https://doi.org/10.3390/mi9100481 - 20 Sep 2018
Cited by 4 | Viewed by 1598
Abstract
In this paper, a novel, hybrid-integrated, high-precision, vacuum microelectronic accelerometer is put forward, based on the theory of field emission; the accelerometer consists of a sensitive structure and an ASIC interface (application-specific integrated circuit). The sensitive structure has a cathode cone tip array, [...] Read more.
In this paper, a novel, hybrid-integrated, high-precision, vacuum microelectronic accelerometer is put forward, based on the theory of field emission; the accelerometer consists of a sensitive structure and an ASIC interface (application-specific integrated circuit). The sensitive structure has a cathode cone tip array, a folded beam, an emitter electrode, and a feedback electrode. The sensor is fabricated on a double-sided polished (1 0 0) N-type silicon wafer; the tip array of the cathode is shaped by wet etching with HNA (HNO3, HF, and CH3COOH) and metalized by TiW/Au thin film. The structure of the sensor is finally released by the ICP (inductively coupled plasma) process. The ASIC interface was designed and fabricated based on the P-JFET (Positive-Junction Field Effect Transistor) high-voltage bipolar process. The accelerometer was tested through a static field rollover test, and the test results show that the hybrid-integrated vacuum microelectronic accelerometer has good performance, with a sensitivity of 3.081 V/g, the non-linearity is 0.84% in the measuring range of −1 g~1 g, the average noise spectrum density value is 36.7 μV/ Hz in the frequency range of 0–200 Hz, the resolution of the vacuum microelectronic accelerometer can reach 1.1 × 10−5 g, and the zero stability reaches 0.18 mg in 24 h. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
LSS-RM: Using Multi-Mounted Devices to Construct a Lightweight Site-Survey Radio Map for WiFi Positioning
Micromachines 2018, 9(9), 458; https://doi.org/10.3390/mi9090458 - 12 Sep 2018
Cited by 3 | Viewed by 1568
Abstract
A WiFi-received signal strength index (RSSI) fingerprinting-based indoor positioning system (WiFi-RSSI IPS) is widely studied due to advantages of low cost and high accuracy, especially in a complex indoor environment where performance of the ranging method is limited. The key drawback that limits [...] Read more.
A WiFi-received signal strength index (RSSI) fingerprinting-based indoor positioning system (WiFi-RSSI IPS) is widely studied due to advantages of low cost and high accuracy, especially in a complex indoor environment where performance of the ranging method is limited. The key drawback that limits the large-scale deployment of WiFi-RSSI IPS is time-consuming offline site surveys. To solve this problem, we developed a method using multi-mounted devices to construct a lightweight site-survey radio map (LSS-RM) for WiFi positioning. A smartphone was mounted on the foot (Phone-F) and another on the waist (Phone-W) to scan WiFi-RSSI and simultaneously sample microelectromechanical system inertial measurement-unit (MEMS-IMU) readings, including triaxial accelerometer, gyroscope, and magnetometer measurements. The offline site-survey phase in LSS-RM is a client–server model of a data collection and preprocessing process, and a post calibration process. Reference-point (RP) coordinates were estimated using the pedestrian dead-reckoning algorithm. The heading was calculated with a corner detected by Phone-W and the preassigned site-survey trajectory. Step number and stride length were estimated using Phone-F based on the stance-phase detection algorithm. Finally, the WiFi-RSSI radio map was constructed with the RP coordinates and timestamps of each stance phase. Experimental results show that our LSS-RM method can reduce the time consumption of constructing a WiFi-RSSI radio map from 54 min to 7.6 min compared with the manual site-survey method. The average positioning error was below 2.5 m with three rounds along the preassigned site-survey trajectory. LSS-RM aims to reduce offline site-survey time consumption, which would cut down on manpower. It can be used in the large-scale implementation of WiFi-RSSI IPS, such as shopping malls, hospitals, and parking lots. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Activity Monitoring with a Wrist-Worn, Accelerometer-Based Device
Micromachines 2018, 9(9), 450; https://doi.org/10.3390/mi9090450 - 10 Sep 2018
Cited by 14 | Viewed by 2205
Abstract
This study condenses huge amount of raw data measured from a MEMS accelerometer-based, wrist-worn device on different levels of physical activities (PAs) for subjects wearing the device 24 h a day continuously. In this study, we have employed the device to build up [...] Read more.
This study condenses huge amount of raw data measured from a MEMS accelerometer-based, wrist-worn device on different levels of physical activities (PAs) for subjects wearing the device 24 h a day continuously. In this study, we have employed the device to build up assessment models for quantifying activities, to develop an algorithm for sleep duration detection and to assess the regularity of activity of daily living (ADL) quantitatively. A new parameter, the activity index (AI), has been proposed to represent the quantity of activities and can be used to categorize different PAs into 5 levels, namely, rest/sleep, sedentary, light, moderate, and vigorous activity states. Another new parameter, the regularity index (RI), was calculated to represent the degree of regularity for ADL. The methods proposed in this study have been used to monitor a subject’s daily PA status and to access sleep quality, along with the quantitative assessment of the regularity of activity of daily living (ADL) with the 24-h continuously recorded data over several months to develop activity-based evaluation models for different medical-care applications. This work provides simple models for activity monitoring based on the accelerometer-based, wrist-worn device without trying to identify the details of types of activity and that are suitable for further applications combined with cloud computing services. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
A ΣΔ Closed-Loop Interface for a MEMS Accelerometer with Digital Built-In Self-Test Function
Micromachines 2018, 9(9), 444; https://doi.org/10.3390/mi9090444 - 06 Sep 2018
Cited by 4 | Viewed by 1620
Abstract
Sigma-delta (ΣΔ) closed-loop operation is the best candidate for realizing the interface circuit of MEMS accelerometers. However, stability and reliability problems are still the main obstacles hindering its further development for high-end applications. In situ self-testing and calibration is an alternative way to [...] Read more.
Sigma-delta (ΣΔ) closed-loop operation is the best candidate for realizing the interface circuit of MEMS accelerometers. However, stability and reliability problems are still the main obstacles hindering its further development for high-end applications. In situ self-testing and calibration is an alternative way to solve these problems in the current process condition, and thus, has received a lot of attention in recent years. However, circuit methods for self-testing of ΣΔ closed-loop accelerometers are rarely reported. In this paper, we propose a fifth-order ΣΔ closed-loop interface for a capacitive MEMS accelerometer. The nonlinearity problem of the system is detailed discussed, the source of it is analyzed, and the solutions are given. Furthermore, a built-in self-test (BIST) unit is integrated on-chip for in situ self-testing of the loop distortion. In BIST mode, a digital electrostatic excitation is generated by an on-chip digital resonator, which is also ΣΔ modulated. By single-bit ΣΔ-modulation, the noise and linearity of excitation is effectively improved, and a higher detection level for distortion is easily achieved, as opposed to the physical excitation generated by the motion of laboratory equipment. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
MEMS Inertial Sensors Based Gait Analysis for Rehabilitation Assessment via Multi-Sensor Fusion
Micromachines 2018, 9(9), 442; https://doi.org/10.3390/mi9090442 - 03 Sep 2018
Cited by 31 | Viewed by 2619
Abstract
Gait and posture are regular activities which are fully controlled by the sensorimotor cortex. In this study, fluctuations of joint angle and asymmetry of foot elevation in human walking stride records are analyzed to assess gait in healthy adults and patients affected with [...] Read more.
Gait and posture are regular activities which are fully controlled by the sensorimotor cortex. In this study, fluctuations of joint angle and asymmetry of foot elevation in human walking stride records are analyzed to assess gait in healthy adults and patients affected with gait disorders. This paper aims to build a low-cost, intelligent and lightweight wearable gait analysis platform based on the emerging body sensor networks, which can be used for rehabilitation assessment of patients with gait impairments. A calibration method for accelerometer and magnetometer was proposed to deal with ubiquitous orthoronal error and magnetic disturbance. Proportional integral controller based complementary filter and error correction of gait parameters have been defined with a multi-sensor data fusion algorithm. The purpose of the current work is to investigate the effectiveness of obtained gait data in differentiating healthy subjects and patients with gait impairments. Preliminary clinical gait experiments results showed that the proposed system can be effective in auxiliary diagnosis and rehabilitation plan formulation compared to existing methods, which indicated that the proposed method has great potential as an auxiliary for medical rehabilitation assessment. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Design of Ensemble Stacked Auto-Encoder for Classification of Horse Gaits with MEMS Inertial Sensor Technology
Micromachines 2018, 9(8), 411; https://doi.org/10.3390/mi9080411 - 17 Aug 2018
Cited by 4 | Viewed by 1611
Abstract
This paper discusses the classification of horse gaits for self-coaching using an ensemble stacked auto-encoder (ESAE) based on wavelet packets from the motion data of the horse rider. For this purpose, we built an ESAE and used probability values at the end of [...] Read more.
This paper discusses the classification of horse gaits for self-coaching using an ensemble stacked auto-encoder (ESAE) based on wavelet packets from the motion data of the horse rider. For this purpose, we built an ESAE and used probability values at the end of the softmax classifier. First, we initialized variables such as hidden nodes, weight, and max epoch using the options of the auto-encoder (AE). Second, the ESAE model is trained by feedforward, back propagation, and gradient calculation. Next, the parameters are updated by a gradient descent mechanism as new parameters. Finally, once the error value is satisfied, the algorithm terminates. The experiments were performed to classify horse gaits for self-coaching. We constructed the motion data of a horse rider. For the experiment, an expert horse rider of the national team wore a suit containing 16 inertial sensors based on a wireless network. To improve and quantify the performance of the classification, we used three methods (wavelet packet, statistical value, and ensemble model), as well as cross entropy with mean squared error. The experimental results revealed that the proposed method showed good performance when compared with conventional algorithms such as the support vector machine (SVM). Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Multi-axis Response of a Thermal Convection-based Accelerometer
Micromachines 2018, 9(7), 329; https://doi.org/10.3390/mi9070329 - 29 Jun 2018
Cited by 3 | Viewed by 1233
Abstract
A thermal convection-based accelerometer was fabricated, and its characteristics were analyzed in this study. To understand the thermal convection of the accelerometer, the Grashof and Prandtl number equations were analyzed. This study conducted experiments to improve not only the sensitivity, but also the [...] Read more.
A thermal convection-based accelerometer was fabricated, and its characteristics were analyzed in this study. To understand the thermal convection of the accelerometer, the Grashof and Prandtl number equations were analyzed. This study conducted experiments to improve not only the sensitivity, but also the frequency band. An accelerometer with a more voluminous cavity showed better sensitivity. In addition, when the accelerometer used a gas medium with a large density and small viscosity, its sensitivity also improved. On the other hand, the accelerometer with a narrow volume cavity that used a gas medium with a small density and large thermal diffusivity displayed a larger frequency band. In particular, this paper focused on a Z-axis response to extend the performance of the accelerometer. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Design and Performance Test of an Ocean Turbulent Kinetic Energy Dissipation Rate Measurement Probe
Micromachines 2018, 9(6), 311; https://doi.org/10.3390/mi9060311 - 20 Jun 2018
Cited by 2 | Viewed by 1540
Abstract
Ocean turbulent kinetic energy dissipation rate is an essential parameter in marine environmental monitoring. Numerous probes have been designed to measure the turbulent kinetic energy dissipation rate in the past, and most of them utilize piezoelectric ceramics as the sensing element. In this [...] Read more.
Ocean turbulent kinetic energy dissipation rate is an essential parameter in marine environmental monitoring. Numerous probes have been designed to measure the turbulent kinetic energy dissipation rate in the past, and most of them utilize piezoelectric ceramics as the sensing element. In this paper, an ocean turbulent kinetic energy dissipation rate measurement probe utilizing a microelectromechanical systems (MEMS) piezoresistor as the sensing element has been designed and tested. The triangle cantilever beam and piezoresistive sensor chip are the core components of the designed probe. The triangle cantilever beam acts as a velocity-force signal transfer element, the piezoresistive sensor chip acts as a force-electrical signal transfer element, and the piezoresistive sensor chip is bonded on the triangle cantilever beam. One end of the triangle cantilever beam is a nylon sensing head which contacts with fluid directly, and the other end of it is a printed circuit board which processes the electrical signal. A finite element method has been used to study the effect of the cantilever beam on probe performance. The Taguchi optimization methodology is applied to optimize the structure parameters of the cantilever beam. An orthogonal array, signal-to-noise ratio, and analysis of variance are studied to analyze the effect of these parameters. Through the use of the designed probe, we can acquire the fluid flow velocity, and to obtain the ocean turbulent dissipation rate, an attached signal processing system has been designed. To verify the performance of the designed probe, tests in the laboratory and in the Bohai Sea are designed and implemented. The test results show that the designed probe has a measurement range of 10−8–10−4 W/kg and a sensitivity of 3.91 × 10−4 (Vms2)/kg. The power spectrum calculated from the measured velocities shows good agreement with the Nasmyth spectrum. The comparative analysis between the designed probe in this paper and the commonly used PNS probe has also been completed. The designed probe can be a strong candidate in marine environmental monitoring. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Design and Application of a High-G Piezoresistive Acceleration Sensor for High-Impact Application
Micromachines 2018, 9(6), 266; https://doi.org/10.3390/mi9060266 - 28 May 2018
Cited by 6 | Viewed by 2296
Abstract
In this paper, we present our work developing a family of silicon-on-insulator (SOI)–based high-g micro-electro-mechanical systems (MEMS) piezoresistive sensors for measurement of accelerations up to 60,000 g. This paper presents the design, simulation, and manufacturing stages. The high-acceleration sensor is realized with one [...] Read more.
In this paper, we present our work developing a family of silicon-on-insulator (SOI)–based high-g micro-electro-mechanical systems (MEMS) piezoresistive sensors for measurement of accelerations up to 60,000 g. This paper presents the design, simulation, and manufacturing stages. The high-acceleration sensor is realized with one double-clamped beam carrying one transversal and one longitudinal piezoresistor on each end of the beam. The four piezoresistors are connected to a Wheatstone bridge. The piezoresistors are defined to 4400 Ω, which results in a width-to-depth geometry of the pn-junction of 14 μm × 1.8 μm. A finite element method (FEM) simulation model is used to determine the beam length, which complies with the resonance frequency and sensitivity. The geometry of the realized high-g sensor element is 3 × 2 × 1 mm3. To demonstrate the performance of the sensor, a shock wave bar is used to test the sensor, and a Polytec vibrometer is used as an acceleration reference. The sensor wave form tracks the laser signal very well up to 60,000 g. The sensor can be utilized in aerospace applications or in the control and detection of impact levels. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Method of Measuring the Mismatch of Parasitic Capacitance in MEMS Accelerometer Based on Regulating Electrostatic Stiffness
Micromachines 2018, 9(3), 128; https://doi.org/10.3390/mi9030128 - 15 Mar 2018
Cited by 10 | Viewed by 1808
Abstract
For the MEMS capacitive accelerometer, parasitic capacitance is a serious problem. Its mismatch will deteriorate the performance of accelerometer. Obtaining the mismatch of the parasitic capacitance precisely is helpful for improving the performance of bias and scale. Currently, the method of measuring the [...] Read more.
For the MEMS capacitive accelerometer, parasitic capacitance is a serious problem. Its mismatch will deteriorate the performance of accelerometer. Obtaining the mismatch of the parasitic capacitance precisely is helpful for improving the performance of bias and scale. Currently, the method of measuring the mismatch is limited in the direct measuring using the instrument. This traditional method has low accuracy for it would lead in extra parasitic capacitive and have other problems. This paper presents a novel method based on the mechanism of a closed-loop accelerometer. The strongly linear relationship between the output of electric force and the square of pre-load voltage is obtained through theoretical derivation and validated by experiment. Based on this relationship, the mismatch of parasitic capacitance can be obtained precisely through regulating electrostatic stiffness without other equipment. The results can be applied in the design of decreasing the mismatch and electrical adjusting for eliminating the influence of the mismatch. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Article
Design, Fabrication, and Performance Characterization of LTCC-Based Capacitive Accelerometers
Micromachines 2018, 9(3), 120; https://doi.org/10.3390/mi9030120 - 09 Mar 2018
Cited by 9 | Viewed by 2862
Abstract
In this paper, two versions of capacitive accelerometers based on low-temperature co-fired ceramic (LTCC) technology are developed, different with respect to the detection technique, as well as the mechanical structure. Fabrication of the key structure, a heavy proof mass with thin beams embedded [...] Read more.
In this paper, two versions of capacitive accelerometers based on low-temperature co-fired ceramic (LTCC) technology are developed, different with respect to the detection technique, as well as the mechanical structure. Fabrication of the key structure, a heavy proof mass with thin beams embedded in a large cavity, which is extremely difficult for the conventional LTCC process, is successfully completed by the optimized process. The LC resonant accelerometer, using coupling resonance frequency sensing which is first applied to LTCC accelerometer and may facilitate application in harsh environments, demonstrates a sensitivity of 375 KHz/g over the full scale range 1 g, with nonlinearity less than 6%, and the telemetry distance is 5 mm. The differential capacitive accelerometer adopting differential capacitive sensing presents a larger full scale range 10 g and lower nonlinearity less than 1%, and the sensitivity is 30.27 mV/g. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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Review

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Review
Monolithic Multi Degree of Freedom (MDoF) Capacitive MEMS Accelerometers
Micromachines 2018, 9(11), 602; https://doi.org/10.3390/mi9110602 - 16 Nov 2018
Cited by 31 | Viewed by 2438
Abstract
With the continuous advancements in microelectromechanical systems (MEMS) fabrication technology, inertial sensors like accelerometers and gyroscopes can be designed and manufactured with smaller footprint and lower power consumption. In the literature, there are several reported accelerometer designs based on MEMS technology and utilizing [...] Read more.
With the continuous advancements in microelectromechanical systems (MEMS) fabrication technology, inertial sensors like accelerometers and gyroscopes can be designed and manufactured with smaller footprint and lower power consumption. In the literature, there are several reported accelerometer designs based on MEMS technology and utilizing various transductions like capacitive, piezoelectric, optical, thermal, among several others. In particular, capacitive accelerometers are the most popular and highly researched due to several advantages like high sensitivity, low noise, low temperature sensitivity, linearity, and small footprint. Accelerometers can be designed to sense acceleration in all the three directions (X, Y, and Z-axis). Single-axis accelerometers are the most common and are often integrated orthogonally and combined as multiple-degree-of-freedom (MDoF) packages for sensing acceleration in the three directions. This type of MDoF increases the overall device footprint and cost. It also causes calibration errors and may require expensive compensations. Another type of MDoF accelerometers is based on monolithic integration and is proving to be effective in solving the footprint and calibration problems. There are mainly two classes of such monolithic MDoF accelerometers, depending on the number of proof masses used. The first class uses multiple proof masses with the main advantage being zero calibration issues. The second class uses a single proof mass, which results in compact device with a reduced noise floor. The latter class, however, suffers from high cross-axis sensitivity. It also requires very innovative layout designs, owing to the complicated mechanical structures and electrical contact placement. The performance complications due to nonlinearity, post fabrication process, and readout electronics affects both classes of accelerometers. In order to effectively compare them, we have used metrics such as sensitivity per unit area and noise-area product. This paper is devoted to an in-depth review of monolithic multi-axis capacitive MEMS accelerometers, including a detailed analysis of recent advancements aimed at solving their problems such as size, noise floor, cross-axis sensitivity, and process aware modeling. Full article
(This article belongs to the Special Issue MEMS Accelerometers)
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