Microelectromechanical Systems-Based Electrochemical Seismic Sensors With Insulating Spacers Integrated Electrodes for Planetary Exploration

This paper presents a microelectromechanical system (MEMS)-based electrochemical seismic sensor for a planetary exploration. An insulating spacer and an electrode of the device are fabricated on one silicon wafer, thus decreasing the number of wafers, facilitating wafer-level alignment and enabling the fabrication of thin insulating spacers (50
$\mu \text{m}$
). The proposed device achieves a sensitivity of 1978.2 V/(m/s) (
$f = 1$
Hz) and a noise level of 100 (nm/s)/Hz
$^{\mathrm {1/2}}$
(3.2 ng/Hz
$^{\mathrm {1/2}}$
,
$f = 0.02$
Hz). Side-by-side random vibration experiment shows that the prosed devices have a correlation coefficient of 0.955±0.029 (
$n = 7$
), indicating a high repeatability. Moreover, the proposed devices located in Beijing can effectively record the seismic motion signal of the Nepal earthquake (over 3000 km away), suggesting a capability of detecting remote quake events.