Design and Development of the MEMS-Based High-g Acceleration Threshold Switch

The paper describes the design, simulation and fabrication of a micro-electromechanical system (MEMS) based acceleration threshold switch with an independent angled latching mechanism. The switch is designed to operate in critical applications wherein power cannot be applied. It is a passive device that does not require power for retention of its mechanical state and mechanical memory. The switch consists of a serpentine spring-mass system with an independent angled latching mechanism and multiple contacts. Stoppers were used to limit displacement in the lateral direction and provide a guided path in the line of action to the proof mass. A transient analysis was performed to study non-linear behaviour of the switch. The latching threshold value was determined analytically based on the geometry of the switch. The switch was fabricated on an SOI (silicon-on-insulator) wafer having 25 mu m thick device layer and 400 mu m handle wafer. The switch was given a static mechanical shock of 3500g to observe its behaviour under shock. Contact resistance of the switch was approximately 2 Omega in the ON position and more than 100 M Omega in OFF position. The theoretical and simulated results were in good agreement with the experimental results.