Fabrication and characterization of a silicon capacitive structure for simultaneous detection of acceleration and angular rate

Monitoring motion parameters is increasingly important in automotive applications and robotics. A silicon micromachined structure 1 cm × 2 cm in size has been designed and fabricated, which can detect linear acceleration g and angular rate ω simultaneously and independently. This is accomplished by capacitive detection of (a) the displacement due to acceleration and (b) the tilt due to centrifugal forces of two seismic masses symmetrically suspended by torsion bars. The ratio of the respective sensitivities to acceleration g and angular rate ω can be adjusted through the dimensions and the shape of the torsion bars.