An Axial-beam Piezoresistive Accelerometer for High-performance Crash Detection of Automotive Industry

A high-performance piezoresistive accelerometer is developed for crash assessment of automobiles. For meeting the technical requirements, a novel sensor scheme is used that features both high sensitivity and high dynamic characteristics (including high resonant frequency and precise damping ratio). A three-beam seismic mass structure is proposed with the combination of a comb damper. Considering the demand in low-cost volume production, standard silicon wafers (instead of SOI wafers) are used here for micro-fabrication of the sensors. Double-sided deep RIE is processed for the micromechanical structure that is combined with the piezoresistive integration process. Test results show that the normalized sensitivity of the accelerometer is measured as 0.11 mV/g/5V within the full-range of 2000 g. The resonance frequency is 31 KHz, with the band of plusmn5% variation in sensitivity wider than 5 kHz 15000 g shocking test has been implemented to the packaged device, resulting in safe survival.