Design and analysis of micro inertial switch with magnetic latch and adjustable threshold

In this paper, a novel microelectromechanical system (MEMS) inertial switch with self-latching mechanism and adjustable acceleration threshold is proposed. The switch consisted of a proof mass suspended by flexible springs. Permanent magnets, ferromagnets and planer coils were integrated in the device to realize the latching and threshold tuning mechanism. The centrifugal experiment and laser based position measurement have been conducted to measure the acceleration threshold and the stiffness of the spring respectively. The inertial threshold value and the spring stiffness were measured as 5.27 g and 163.12 N/m. The discrepancy between measured acceleration threshold results (5.27 g) and the analytical acceleration threshold results (5 g) is mainly due to the dimension errors during device fabrication. By applying a reverse current of 0.1 A, the switch can be unlatched from its 'on-state'. Experiment also demonstrates that by applying a current varying from - 0.5 A to 0.5 A, the threshold value can be adjusted from 6 g to 3.75 g.