Capacitive slanted-beam three-axis accelerometer: I. Modelling and design

Three-axis accelerometers based on four separate seismic masses, each one suspended on a slanted beam, have previously been shown to have identical resolution and frequency responses in all directions. Here, a new and in-depth model of such accelerometers is presented. The theoretical model incorporates non-ideal effects such as the finite aspect ratio of the beam and the frequency-dependent squeezed gas-film damping. Sensitivity, resolution, transverse sensitivity and process errors are discussed. Prototype devices have been fabricated in a straightforward silicon process.