Prediction of Gap Asymmetry in Differential Micro Accelerometers

Sensors

Wu Zhou²  Baili Li³  Bei Peng²  Wei Su¹ 

[1] Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China; E-Mails:;School of Mechatronics Engineering, University of Electronic Technology and Science of China, Chengdu 611731, China; E-Mail:;School of Mechanical Engineering, University of Southwest Jiaotong University, Chengdu 610031, China; E-Mail:

关键词: MEMS;    accelerometer;    asymmetry;    analytical method;   

DOI  :  10.3390/s120606857

来源: mdpi

【 摘 要 】

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.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland