A two degrees of freedom comb capacitive-type accelerometer with low cross-axis sensitivity

  • M. N. Nguyen International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No1 Dai Co Viet Road, Hai Ba Trung, Hanoi, Vietnam, Phone: +84-24-38680786.
  • L. Q. Nguyen International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No1 Dai Co Viet Road, Hai Ba Trung, Hanoi, Vietnam, Phone: +84-24-38680786.
  • H. M. Chu International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No1 Dai Co Viet Road, Hai Ba Trung, Hanoi, Vietnam, Phone: +84-24-38680786.
  • H. N. Vu International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No1 Dai Co Viet Road, Hai Ba Trung, Hanoi, Vietnam, Phone: +84-24-38680786.
Keywords: Comb capacitive-type accelerometer, SOI-micromachining, folded-beam spring, cross-axis sensitivity

Abstract

In this paper, we report on a SOI-based comb capacitive-type accelerometer that senses acceleration in two lateral directions. The structure of the accelerometer was designed using a proof mass connected by four folded-beam springs, which are compliant to inertial displacement causing by attached acceleration in the two lateral directions. At the same time, the folded-beam springs enabled to suppress cross-talk causing by mechanical coupling from parasitic vibration modes. The differential capacitor sense structure was employed to eliminate common mode effects. The design of gap between comb fingers was also analyzed to find an optimally sensing comb electrode structure. The design of the accelerometer was carried out using the finite element analysis. The fabrication of the device was based on SOI-micromachining. The characteristics of the accelerometer have been investigated by a fully differential capacitive bridge interface using a sub-fF switched-capacitor integrator circuit. The sensitivities of the accelerometer in the two lateral directions were determined to be 6 and 5.5 fF/g, respectively. The cross-axis sensitivities of the accelerometer were less than 5%, which shows that the accelerometer can be used for measuring precisely acceleration in the two lateral directions. The accelerometer operates linearly in the range of investigated acceleration from 0 to 4g. The proposed accelerometer is expected for low-g applications.

Published
2019-09-27
How to Cite
Nguyen, M. N., Nguyen, L. Q., Chu, H. M., & Vu, H. N. (2019). A two degrees of freedom comb capacitive-type accelerometer with low cross-axis sensitivity. Journal of Mechanical Engineering and Sciences, 13(3), 5334 - 5346. https://doi.org/10.15282/jmes.13.3.2019.09.0435