A MEMS inertial switch with a single circular mass for universal sensitivity

A novel micro-electro-mechanical systems (MEMS) inertial switch with universal sensitivity was investigated in this paper. Using a single circular mass, the switch was able to detect accelerations in all of the radial directions of a hemisphere. Four suspended springs with 90 degrees symmetry were employed to be compliant in all directions, and flexible stationary electrodes were used to allow for long-duration contact. More than forty switch prototypes were produced using a microfabrication process. Dynamic finite element analysis and shock table experiment were carried out to study the behavior of the proposed switch. The results indicated that universal sensitivity was successfully achieved by the new design. Agreement was achieved between the numerical predictions and actual test results for the acceleration thresholds in the different sensitive directions of a hemisphere.