In this work, MEMS inertial switches intended to be triggered at multiple acceleration thresholds in two directions were implemented and proven effective. The switches consume virtually no power in their open switching state. Multiple acceleration thresholds can be beneficial in triggering different actions for different acceleration events. Low power consumption can aid in their use for portable applications such as in cycling helmets. The developed designs rely mainly on a suspended shuttle mass, which is used to implement one of two methods of actuation. The first relies on simple contact between the moving shuttle mass and a flexible electrode. In the second, the pull-in instability is induced by applying a voltage between a cantilever and an electrode, and then having the shuttle mass force the cantilever moving towards the electrode as it moves under the applied acceleration. Ten designs varying in their actuation method, suspension design, intended acceleration thresholds, and dimensions were modeled using a finite element model, fabricated, through the SOIMUMPs process, and then electrically and mechanically tested. Mechanical testing has been conducted using Drop-table tests and mechanical shakers. The simple contact devices were proven effective through shock test results showing triggering at two acceleration thresholds in two directions. Initial results also were promising for the pull-in based devices showing switching by moving their shuttle mass with a probe while applying appropriate voltage and observing under a microscope.
|Date made available
|KAUST Research Repository