A self-diagnostic airbag accelerometer with skew-symmetric proof-mass

Abstract

This paper describes the design, fabrication and testing of a piezoresistive cantilever-beam microaccelerometer for automobile airbag applications. Fabricated devices show a resonant frequency of 2.07kHz, a sensitivity of 65pVIglV with a nonlinearity of 4% over f50g ranges. Flat amplitude response and frequency-proportional phase response indicate that 70% of critical damping level has been accurately achieved in the fabricatcd devices. Novel aspects of this work include: a skewsymmetric proof-mass design for self-diagnostic capability and zero transverse sensitivity; a multi-step anisotropic etching process for beam thickness control and fillet-rounding formation; the use of UV-curing paste for silicon-to-glass bonding. It is shown that the new aspects of this work are used to yield a simple, practical and effective mean for improving the performance, reliability, robusmess, process simplicity as well as the reproducibility of the accelerometers.