A Low-g MEMS Inertial Switch Based on Direct Contact Sensing Method

A microelectromechanical systems (MEMS) low-g inertial switch is typically used for linearly increased/decreased acceleration signal sensing. In this paper, we introduce a novel design concept of MEMS inertial switch based on direct contact sensing method to eliminate the bouncing effect of the output signal. The switch was designed with a threshold value of 12 g and composed by a proof mass, suspended by six Z-shaped flexure beams. The fabrication was carried out on a silicon-on-insulator (SOI) wafer with standard silicon micromachining. Two glass wafers were used to encapsulate the switch and establish a direct connection between the movable electrode and the detection circuits. According to the centrifugal experiment results, the measured threshold value is around 11.8 g, which is in good agreement with the designed value. The comparison of contact behavior between direct and indirect contact switches was also carried out. The results showed that the direct contact switch could eliminate the output signal bouncing effect, especially when the applied acceleration signal was approximate to the threshold value of the switch.