A Novel Low-g MEMS Bistable Inertial Switch With Self-Locking and Reverse-Unlocking Functions

Abstract

Based on a bistable mechanism, a novel low-g MEMS inertial switch with dual functions of self-locking and reverse-unlocking is presented, along with its fabrication and verification. This MEMS switch is fabricated on a Silicon-On-Insulator (SOI) wafer by using deep reactive ion etching (DRIE), Bosch processing, and wafer bonding technologies. A two-level system is proposed to realize dual functions of this switch, which mainly consists of a spring-mass-damping system as the first level and a bistable structure as the second level. According to the finite element analysis (FEA), the theoretical formula of the bistable structure has been successfully verified to deduce the static mechanical properties. Under positive and negative acceleration excitations, the dynamic response characteristics of the switch has been systematically simulated further. Furthermore, this inertial switch has been tested by using a centrifugal acceleration turntable, and its self-locking threshold and reverse unlocking threshold are 8 g and 105 g, respectively. Finally, the contact resistance of this MEMS switch is measured about 0.75 Ω by a probe station.