An Optical Interferometry Based MEMS Accelerometer Applicable to Seismic-Grade Measurement
Cheng Li, Bo Yang, Xiang Zheng, Zhenyu Sun, Luqiang Zhou, Xin Huang, Xin Guo
Abstract
Traditional seismometers and gravimeters normally have large volumes and entail high manufacturing costs. Aiming at the miniaturization of such geophysical instruments, a portable Micro-electro-mechanical Systems (MEMS) accelerometer applicable to seismic-grade measurements is fabricated and characterized in this work. This accelerometer is operating on the deformable grating-based MEMS interferometer, where a new MEMS out-of-plane sensing chip employing double layers of 10 μm-thickness spring is first proposed. The simulation results show that this geometry has a low natural frequency of 52.23 Hz and undergoes a low stress of 26.94 Mpa under the gravitational acceleration. The test of the fabricated prototype is implemented in a quiet environment for tracking the inherent micro seismic peaks of Earth. The evaluation results demonstrate that the fabricated prototype has achieved a voltage sensitivity of 510.6 V/g. Furthermore, the noise estimation indicates that the self-noise of this sensor has reached 20 ng/√<i>Hz</i> from 0.3 Hz to 20 Hz, and a bias stability of 235.4 ng is obtainable at room temperature. Combined with the compact package size of 40.5 cm<sup>3</sup>, the proposed device exhibits a promising prospect in the seismic-grade applications.