Design, modeling, and testing of a bidirectional multi-threshold MEMS inertial switch

We present a MEMS inertial switch with multiple, non-latching acceleration thresholds in two directions, that consumes no power in its inactive state. The design implements a suspended proof mass, with stationary electrodes placed at different positions in its sensitive direction so that different shock-induced displacements of the proof mass will result in contact/actuation at the stationary electrodes corresponding to the applied acceleration levels. This allows for automatic acceleration-based action, as a switch, or categorization for acceleration as a binary sensor. The designs were modeled using a finite-element simulation. The device was fabricated through SOIMUMPS and then tested using a drop-table shock system. The experimental results were close to the performed simulations with acceleration thresholds of 69 g and 121 g.