A Novel Micro-Machined Out-of-Plane Resonant Accelerometer with Differential Structure of Different-Height Resonant Beams

A novel micro-machined out-of-plane resonant accelerometer with a differential structure is presented. The micro-machined accelerometer consists of two identical torsional structures with asymmetric mass distribution, torsion beam and two different-height resonant beams. Due to the asymmetric mass distribution, the two mirror-symmetrical-placed torsional structures turn an angle under an out-of-plane acceleration, which makes the different-height resonant beam connected to the structures bear different axial stresses, outputting a differential resonant frequency shift. A multi-layer mask etching process based on silicon-on-glass micro-machined technology was employed to fabricate the differential structure and the different-height resonant beams. Primary experiment shows the differential sensitivity of out-of-plane acceleration is 32Hz/g at the resonant frequency of 21.41 kHz.