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 75 g by using various PDMS caps. The measured results are in good agreement with the analytical results.

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► We developed a novel inertial switch which can adjust acceleration thresholds.
► The PDMS cap is used to adjust states of inertial switch.
► The unlatching mechanism is demonstrated by rotating the proof-mass.
► Parylene-C suspension structure can be used to reduce the stiffness of the M-DAC.
► The thresholds can be varied from 40 g to 75 g.