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Prediction of Gap Asymmetry in Differential Micro Accelerometers
School of Mechatronics Engineering, University of Electronic Technology and Science of China, Chengdu 611731, China
School of Mechanical Engineering, University of Southwest Jiaotong University, Chengdu 610031, China
Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China
* Author to whom correspondence should be addressed.
Received: 16 April 2012; in revised form: 13 May 2012 / Accepted: 22 May 2012 / Published: 25 May 2012
Abstract: Gap asymmetry in differential capacitors is the primary source of the zero bias output of force-balanced micro accelerometers. It is also used to evaluate the applicability of differential structures in MEMS manufacturing. Therefore, determining the asymmetry level has considerable significance for the design of MEMS devices. This paper proposes an experimental-theoretical method for predicting gap asymmetry in differential sensing capacitors of micro accelerometers. The method involves three processes: first, bi-directional measurement, which can sharply reduce the influence of the feedback circuit on bias output, is proposed. Experiments are then carried out on a centrifuge to obtain the input and output data of an accelerometer. Second, the analytical input-output relationship of the accelerometer with gap asymmetry and circuit error is theoretically derived. Finally, the prediction methodology combines the measurement results and analytical derivation to identify the asymmetric error of 30 accelerometers fabricated by DRIE. Results indicate that the level of asymmetry induced by fabrication uncertainty is about ±5 × 10−2, and that the absolute error is about ±0.2 µm under a 4 µm gap.
Keywords: MEMS; accelerometer; asymmetry; analytical method
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MDPI and ACS Style
Zhou, W.; Li, B.; Peng, B.; Su, W.; He, X. Prediction of Gap Asymmetry in Differential Micro Accelerometers. Sensors 2012, 12, 6857-6868.
Zhou W, Li B, Peng B, Su W, He X. Prediction of Gap Asymmetry in Differential Micro Accelerometers. Sensors. 2012; 12(6):6857-6868.
Zhou, Wu; Li, Baili; Peng, Bei; Su, Wei; He, Xiaoping. 2012. "Prediction of Gap Asymmetry in Differential Micro Accelerometers." Sensors 12, no. 6: 6857-6868.