Design Of Accelerometer Research Articles

Thermo-Structural Coupled Topology Optimization of Micro-Capacitive Accelerometer

In order to enhance the working performance of micro-capacitive accelerometer in high temperature environment, the structure topology optimization of a micro-capacitive accelerometer is proposed. After the study of thermo-structural coupled governing equations and sensitivity analysis, the mass-block and elastic-beam structure of comb micro-capacitive accelerometer topology optimization model is established. Then the optimal topology forms of mass-block and elastic-beam structure are obtained with the MMA (method of moving asymptotes) method. At last, the calculating results indicate that the maximum deformation at acceleration detection direction is only 22nm at the operating temperature range of 0~300°C, which less than the maximum deformation of the limit value (25nm), and provides a reliable way for innovative design of micro-capacitive accelerometer.

Development of multiple performance indices and system parameter study for the design of a MEMS accelerometer

For the design of a MEMS accelerometer, proper performance indices should be defined and employed. Performance indices are obtained using either an experimental method or a numerical method. In the present study, a vibration analysis model of a MEMS accelerometer is introduced to calculate three performance indices: sensitivity, measurable acceleration range, and measurable frequency range. The accuracy of the vibration analysis model is first validated by comparing its modal and transient results with those of a commercial finite element code. Measurable acceleration and frequency ranges versus allowable errors for electrical and mechanical sensitivities are obtained and the effects of system parameter variations on the three performance indices are investigated.

Design of MEMS accelerometer based acceleration measurement system for automobiles

Design of an acceleration measurement system using a MEMS accelerometer to measure acceleration of automobiles in all the three axes is presented. Electronic stability control and anti-lock breaking systems in automobiles use the acceleration measurements to offer safety in driving. The system uses an ARM microcontroller to quantize the outputs of accelerometer and save the measurement data on a microSD card. A LabVIEW program has been developed to analyze the longitudinal acceleration measurement data and test the measurement system. Random noises generated and added with measurement data during measurement are filtered by a Kalman filter implemented in LabVIEW. Longitudinal velocity of the vehicle is computed from the measurement data and displayed on a graphical chart. Typical measurement of velocity of a vehicle at different accelerations and decelerations is presented.

Design, fabrication and testing of a high performance silicon piezoresistive Z-axis accelerometer with proof mass-edge-aligned-flexures

This paper presents design, fabrication and testing of a quad beam silicon piezoresistive Z-axis accelerometer with very low cross-axis sensitivity. The accelerometer device proposed in the present work consists of a thick proof mass supported by four thin beams (also called as flexures) that are connected to an outer supporting rim. Cross-axis sensitivity in piezoresistive accelerometers is an important issue particularly for high performance applications. In the present study, low cross-axis sensitivity is achieved by improving the device stability by placing the four flexures in line with the proof mass edges. Various modules of a finite element method based software called CoventorWare™ was used for design optimization. Based on the simulation results, a flexure thickness of 30 μm and a diffused resistor doping concentration of 5 × 1018 atoms/cm3 were fixed to achieve a high prime-axis sensitivity of 122 μV/Vg, low cross-axis sensitivity of 27 ppm and a relatively higher bandwidth of 2.89 kHz. The designed accelerometer was realized by a complementary metal oxide semiconductor compatible bulk micromachining process using a dual doped tetra methyl ammonium hydroxide etching solution. The fabricated accelerometer devices were tested up to 13 g static acceleration using a rate table. Test results of fabricated devices with 30 μm flexure thickness show an average prime axis sensitivity of 111 μV/Vg with very low cross-axis sensitivities of 0.652 and 0.688 μV/Vg along X-axis and Y-axis, respectively.

Design and Analysis of a Piezoresistive Accelerometer with the Film-Island Structure

In this paper, we propose a piezoresistive accelerometer with the film- island structure, whose working range is up to 100,000g. Compared with the beam-island structure, the film-island structure has some advantages. With the film squeezed, the damping and the stiffness increase whereas the transverse sensitivity decreases. The fragmentation can be avoided in the overload situation. The damping characteristics, which are crucial for this accelerometer design, are theoretically analyzed in depth, and are verified by FEM simulation with ANSYS.

Design of an Accelerometer-Controlled Myoelectric Human Computer Interface

The purpose of this study is to develop an alternate in-air input device which is intended to make interaction with computers easier for amputees. This paper proposes the design and utility of accelerometer controlled Myoelectric Human Computer Interface (HCI). This device can function as a PC mouse. The two dimensional position control of the mouse cursor is done by an accelerometer-based method. The left click and right click and other extra functions of this device are controlled by the Electromyographic (EMG) signals. Artificial Neural Networks (ANNs) are used to decode the intended movements during run-time. ANN is a pattern recognition based classification. An amputee can control it using phantom wrist gestures or finger movements.

Design of Double T-Shape Accelerometer Based on MEMS

A novel structure is proposed to design accelerometer, that is, two parallel cantilever beams are selected instead of single-beam, which would effectively improve accelerometer’s sensitivity. The novel structure can be integrated fabricated, which is suit for lot manufacturing. The characteristic parameters of the microstructure are analyzed by ANSYS. It can be concluded that the sensitivity is, anti-overload capacity is 1e5g, measuring range is±20g.The microstructure is manufactured by means of the silicon-on-insulator craft and the thickness of the beam is 20 um, the length is 3500 um. The test results show that the resonance frequency is 1840Hz, which is consistent with the results of the calculation and simulation.

RFID-Based Thermal Bubble Non-Floating Type Accelerometer with Semi-Cylindrical Chamber and Filled with Xenon Gas

This research proposes a wireless RFID-based thermal bubble accelerometer design, and relates more particularly for the technology to manufacture and package it on a flexible substrate. The key technology is to integrate both a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for fabrication and usage. In this paper the heaters as well as the thermal sensors are directly adhering on the surface of the flexible substrate without the traditional floating structure. Thus the structure is much simpler and cheaper for manufacturing, and much more reliable in large acceleration impact condition without broken. Furthermore, the molecular weight of xenon gas is much larger than carbon dioxide, thus the performance of the accelerometer will be increased. In addition, the shape of the chamber is changed as a semi-cylindrical one instead of the conventional rectangular type. Comparisons of sensitivity and response time are also made; one can see the performances of the proposed new design with either semi-cylindrical chamber or filled with xenon gas are better.

An in-plane SiGe differential capacitive accelerometer for above-IC integration

MEMS above-IC monolithic integration can yield a very compact device with good cost-effectiveness. One of the major challenges for this technology is to protect the CMOS from the heat introduced by the MEMS fabrication. In this paper, we present the design and fabrication of a novel lateral capacitive accelerometer, utilizing a low thermal budget SiGe MEMS technology. The accelerometer features a 4 µm SiGe structural layer thickness with a shock protector gap of 500 nm. Benefiting from the low temperature (∼450 °C) SiGe MEMS technology, this inertial device demonstrates the achievability of fabricating above-IC mechanical sensors by 3D stacking. In this paper, the accelerometer design will be introduced first, followed by the introduction of the low thermal budget SiGe MEMS fabrication process. The fabricated devices have been characterized with a network/spectrum analyzer. Both a frequency sweep and a dc voltage sweep have been conducted. These electrostatic characterization results will be analyzed and compared with the design model.

Numerical prototyping methods in microsystem accelerometers design

The authors of this research would like to present the numerical prototyping methods in reference to design of microsystem silicon accelerometer. As an example device the capacitive accelerometer was taken into account. The accelerometer was prepared as a FEM parametric model. The model was then processed by the numerical optimization algorithms in order to find the optimal design parameters. For this purpose, the so-called numerical multi-objective optimization process was carried out. The idea was to find the optimal solution in reference to more than one optimizing criterion. As a result the set of optimal solutions was obtained and this method seems to be promising for similar purposes.

Wireless RFID-Based Thermal Bubble Type Accelerometer and Monitor System Design

This research proposes a wireless RFID-based thermal bubble accelerometer design, and relates more particularly for the technology to manufacture it on a flexible substrate. The key technology is to integrate both a thermal bubble accelerometer and a wireless RFID antenna on the same substrate, such that the accelerometer is very convenient for usage. In this paper we use xenon inert gas in the chamber with heavier molecular weight to increase the acceleration sensitivity instead of traditional air or carbon dioxide. On the other hand, the specific heat of xenon gas is also lower so that the bandwidth of the proposed accelerometer is larger and the power consumption is lower. In addition, the inner shape of the chamber is changed as hemisphere instead of rectangular type, comparisons are also made. We have seen that the sensitivity of the proposed design is better.

Modal Analysis of a Six-Axis Accelerometer

The undamping differential vibration equation of a six-axis accelerometer was derived based on the Lagrange equation. The theory of matrix iteration was introduced to solve the inherent frequencies and corresponding mode shapes of the six-axis accelerometer, and the theory can also avoid solving high-order differential equation which will happen in the traditional theories. The steps of matrix iteration were described in detail. It was found that every element of the system inertial matrix and stiff matrix is the function of the structure parameters in the calculation. For expanding the measuring range of the accelerometer and increasing the basic frequency, the relationship figures between the basic frequency and the structure parameters of the accelerometer were plotted by means of programming, which supplies the theoretical basis for the structure parameter optimization design of a six-axis accelerometer.

Design of an SOI-MEMS high resolution capacitive type single axis accelerometer

In recent years, high resolution micro accelerometers are increasingly finding various applications in different segments of life. The current work deals with the design of a high resolution single axis accelerometer based on SOI-MEMS technology. Accordingly two different approaches for designing comb type, capacitive, SOI-MEMS accelerometer is presented. Initially a system level approach using a simulation platform from SABER is carried out to obtain the basic design. Later, a device level design is carried out by building three dimensional (3D) geometric models using finite element (FE) simulations through CoventorWare software. Different design parameters like mechanical and electrical sensitivity, capacitance values, resonant frequency, etc. are obtained in either of the cases and compared. The design is optimized based on the overall sensitivity and the system noise level both electrical and mechanical, respectively. The complete design is worked out in accordance with the silicon on insulator based multiuser MEMS fabrication processes (MUMPs) technology from MEMSCAP foundry.

An automated CAE system for multidisciplinary structural design: its application to micro accelerometer

This paper describes a new computer-aided engineering system for multidisciplinary structural design. An automatic finite element mesh generation technique, based on fuzzy knowledge processing and computational geometry, is incorporated into the system, together with one of the commercial finite element analysis codes. A bubble is generated if its distance from existing bubble points is similar to the bubble-spacing function at the point. The bubble-spacing function is well controlled by fuzzy knowledge processing. The Delaunay method is employed as a basic tool for element generation. Automatic finite element generation for three-dimensional MEMS holds great benefits for analyses. An optimum design solution or satisfactory solutions will be automatically searched using the genetic algorithms modified for real search space, together with the automated finite element analysis system. A novel CAE system was developed, and successfully applied to the shape design of a micro accelerometer based on a tunneling current concept.

Design and analysis of SOI special gigh-g MEMS accelerometer

Design and analysis of SOI special gigh-g MEMS accelerometer

Optical accelerometer based on high-order diffraction beam interference

We design and fabricate a novel optical accelerometer based on high-order diffraction beam interference with a built-in phase-generated carrier modulator. A proof-of-concept prototype is tested and achieves a resolution of 96 ng/√Hz with a dynamic range of 60 g. By employing optical interference between ±1 order diffraction beams from a grating translating perpendicular to an optical beam for acceleration sensing, the accelerometer realizes a wide dynamic range, while maintaining a high resolution. Compared with prior optical accelerometers, the interference in this structure is free from the effect of short coherence length or beam divergence, and a greater than ordinary dynamic range is obtained. The proposed design is also applicable to a MOEMS platform, offering a new thought in the design of high-performance MOEMS accelerometers.

New capacitive low-g triaxial accelerometer with low cross-axis sensitivity

This work describes a compact accelerometer, which integrates three spring-proof mass systems into a single structure to sense triaxial motion. It has a size of 1.3 × 1.28 mm2 and an operating range of ±1 g. Silicon-on-glass (SOG) micromachining and deep reactive-ion etching (DRIE)-based process are adopted to fabricate this accelerometer with a high-aspect-ratio sensing structure. The accelerometer has an excellent z-axis output sensitivity of 1.434 V g−1 and a high resolution of 49 µg Hz−1/2. The sensitivity and minimum cross-axis sensitivity of the x-axis in-plane accelerometer are 1.442 V g−1 and 0.03% and those of the y-axis accelerometer are 1.241 V g−1 and 0.21%, respectively. The new in-plane and out-of-plane accelerometer design exhibits high cross-axis sensitivity immunity, high sensitivity and high linearity suggesting that the triaxial accelerometer has the potential for use in future applications in consumer goods and the cellular phone market.

Formulation of stiffness constant and effective mass for a folded beam

Stiffness constant and effective mass are two important parameters in the performance analysis of an accelerometer. Their values depend mostly on the structural design of the comb finger-type accelerometer, especially its suspension beam design. In this study, the formulation of the stiffness constant and effective mass is derived successfully from theoretical analysis. The performance of the accelerometer can be analyzed using common designs of its suspension beam. The results obtained are comparable with other published results and those obtained from the finite element (FE) analysis.

A miniature in-plane piezoresistive MEMS accelerometer for detection of slider off-track motion in hard disk drives

A miniature in-plane pizoresistive MEMS accelerometer was designed, fabricated and characterized for detection of slider off-track motion in hard disk drives. The structure of the accelerometer consists of a central supporting beam and two stress-magnifying sensing beams. Under geometric constraints imposed by the trailing side of a pico slider, the accelerometer design was optimized to achieve approximately pure axial deformation in the sensing beams and a maximum sensitivity with a specified natural frequency of 300 kHz. Fabricated on a silicon-on-insulator (SOI) wafer, the accelerometer with a half Wheatstone bridge was wirebonded to external pads and interfaced with an amplifier circuit on a printed circuit board (PCB). The noise level, sensitivity, nonlinearity were characterized with vibration testing on a shaker. The miniature accelerometer (1 × 0.3 × 0.3 mm3) with a weight of only 0.2 mg offers a much higher resonant frequency with a comparable sensitivity compared with those in previous work.

Design and characterization of a CMOS compatible poly-SiGe lowg capacitive accelerometer

This paper presents the design and characterization of a CMOS compatible low-g capacitive accelerometer, fabricated in a low thermal budget poly-SiGe MEMS technology. The out-of-plane single axial device features a large effective capacitive surface, low cross talk and a robust beam suspension. The structural layer thickness of the accelerometer is 4 μm. First, the accelerometer design is described, followed by an overview of the fabrication and characterization process. The released devices have been electro-statically analyzed, with an impedance analyzing system, in order to verify the DC responses of the devices to bias voltage sweeps. Then, the devices are encapsulated in a DIL (Dual-in Line) package for the vibration and angular characterizations. The dynamic responses of the poly-SiGe devices are compared to those of a piezoelectric reference accelerometer. The results demonstrate for the first time the achievability of fabricating large sensing area, low g accelerometers with the above-CMOS poly-SiGe technology.