Abstract
This paper presents a micromachined micro-g capacitive accelerometer with a silicon-based spring-mass sensing element. The displacement changes of the proof mass are sensed by an area-variation-based capacitive displacement transducer that is formed by the matching electrodes on both the movable proof mass die and the glass cover plate through the flip-chip packaging. In order to implement a high-performance accelerometer, several technologies are applied: the through-silicon-wafer-etching process is used to increase the weight of proof mass for lower thermal noise, connection beams are used to reduce the cross-sensitivity, and the periodic array area-variation capacitive displacement transducer is applied to increase the displacement-to-capacitance gain. The accelerometer prototype is fabricated and characterized, demonstrating a scale factor of 510 mV/g, a noise floor of 2 µg/Hz1/2 at 100 Hz, and a bias instability of 4 µg at an averaging time of 1 s. Experimental results suggest that the proposed MEMS capacitive accelerometer is promising to be used for inertial navigation, structural health monitoring, and tilt measurement applications.
Highlights
Microelectromechanical systems (MEMS) accelerometers have been widely used in various application fields, such as consumer electronics, automobiles, medical, structural health monitoring, and inertial navigation [1,2,3,4]
According to the displacement or force transduction mechanisms, MEMS accelerometers can be categorized as different types, including piezoelectric [5,6], capacitive [7,8], piezoresistive [9,10], tunneling [11,12], resonant [13,14,15,16], optical [17,18], thermal [19,20], and electromagnetic [21,22] accelerometers
Several experiments, including the tilt table calibration, the noise floor evaluation, and Allan deviation assessment, were conducted and the results showed that the proposed MEMS accelerometer had a scale factor of 510 mV/g, a noise floor of 2 μg/Hz1/2 at 100 Hz, and a bias instability of 4 μg at an averaging time of 1 s
Summary
Microelectromechanical systems (MEMS) accelerometers have been widely used in various application fields, such as consumer electronics, automobiles, medical, structural health monitoring, and inertial navigation [1,2,3,4]. Capacitive transduction is one of the most commonly used technologies for high-performance MEMS accelerometers since it takes advantage of simple structure, low noise, low power consumption, cost-effectiveness, and reliability [4]. Most of the state-of-the-art capacitive MEMS accelerometers use sandwich [23] or comb-finger [24] gap-variation based capacitive displacement transducers. Due to the nonlinear capacitance-to-displacement relationship [25] and pull-in effect [26], gap-variation based capacitive accelerometers generally require closed-loop control, which increases circuit complexity and power consumption. Even though area-variation based capacitive displacement transducers have intrinsically good capacitance-to-displacement linearity and large travel range for open-loop operation, the MEMS inertial sensors based on area-variation
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