A novel inertial switch with an adjustable acceleration threshold using an MEMS digital-to-analog converter
This study presents the development of an inertial switch that uses an MEMS digital-to-analog converter (M-DAC) to adjust acceleration thresholds. The proposed device consists of an M-DAC layer with a proof-mass, latching layer, and PDMS cap. Various PDMS caps can be used to push the selected adjusting plates of the M-DAC layer, generating specific displacement states of the proof-mass, thereby enabling the adjustment of the acceleration thresholds. When an applied acceleration exceeds the specified acceleration threshold, the proof-mass moves up and latches onto the latching layer to record the inertia impact. In addition, the unlatching of the device can be easily achieved by rotating the proof-mass of the M-DAC layer using needles. The suspensions of the M-DAC layer are fabricated with parylene-C to achieve a low stiffness. The latching layer is fabricated using simple KOH etching with corner compensation. The PDMS cap is constructed using SU-8 molds. The acceleration thresholds can be varied from 40 to 75g by using various PDMS caps. The measured results are in good agreement with the analytical results.
inertial switch mems digital-to-analog converter koh etching parylene