High g MEMS inertial switch capable of direction detection

Abstract

This paper proposed a novel microelectromechanical system (MEMS) inertial switch, which can not only capture an acceleration threshold, but also detect the impact direction in a hemisphere. The device includes a single sensitive mass-spring system as movable electrode, and 4 radial and 1 axial flexible stationary electrodes, it is essentially made of five individual electrical switches. The impact loads in different directions can make contact (switch-on) between the mass and one or several stationary electrodes, the acceleration direction intervals can be determined by identifying which electrode contacts with the mass. By dynamic finite element analysis and tests, the mass contacted to the electrodes under high g impact loads were determined to the corresponding acceleration direction intervals. The results of the dynamic tests were in good agreement with the numerical predictions, thus the proposed MEMS inertial switch can be used not only to sense the acceleration threshold, but also to detect the acceleration direction in a 3D space.