Investigate on Characteristics of Gas Film Damping of Capacitive Micro Accelerometers

Abstract

Basing on the rarefied gas dynamics theory and the squeeze film Reynolds equation amended with slip flow boundary condition, the gas film damping effects on the sensitive proof mass, moving along its axial direction, are analyzed for capacitive micro accelerometers. Simplified analysis solutions are obtained for damping force and damping coefficient. Also it shows that gas film damping force is related not only to the accelerometer dimensions and velocity of proof mass, but also to the factors, such as solid wall material, surface roughness, smooth finish, and so on. Finally, it is shown that gas film damping, especially for squeezed-damping, is seriously influenced by Maxwell's reflection coefficient, which needs to be further investigated and analyzed.