Design and simulation of bidirectional impact sensors array with optimized air damped response

This paper developed an array of bidirectional impact switches for low threshold acceleration. The theory of shock and rarefied air damping is described and based on that an optimized damped design is presented. The analytical response of the system is in good agreement with finite element simulation results. The response time of the system for 30 g impact level is about 0.5 ms and the settling time below 2.5 ms shows a fast and accurate response of the system which makes the sensor appropriate in applications such as cars side door air bag deployment. The miniature array of eight sensors consists of four threshold acceleration in two axes with readout contacts and pull in test electrodes placed in a die within 2 mm x 2 mm dimensions. The height of the structure has no effects on the displacement and frequency of the system, therefore the desired damping ratio could be achieved easily.