Squeeze film damping effect on a MEMS torsion mirror

In this paper we discuss the dynamical characteristics of a torsion mirror in microelectromechanical systems. The squeeze film is modeled using the so-called modified molecular gas film lubrication (MMGL) equation with the coupling effects of surface roughness and gas rarefaction. The MMGL equation is linearized and then a simple mapping method is utilized to obtain the analytical solution of the transformed two-dimensional diffusion equation. From the numerical analyses, it is shown that the surface roughness parameter (Peklenik number), the gas rarefaction parameter (inverse Knudsen number) and squeeze film damping frequencies significantly affect the dynamic characteristics (spring and damping coefficients) of the torsion mirror.