Effect of squeeze-film damping on the dynamic behavior of circular and rectangular microplates

The influence of air in MEMS devices can be divided into two categories: slide-film damping and squeeze-film damping, slide-film damping occurs in laterally moving devices (e.g. comb drives), while the squeeze film damping is characteristic for MEMS devices, in which a microstructure moves or bends towards a rigid surface with a thin air film in-between (as in microswitch).For MEMS devices with a plate that moves against a trapped film, squeeze film damping is a very important problem which substantially affects the system frequency response. This phenomenon occurs because when the flexible microplate vibrates, the fluid underneath the plate begins to move outward the medium gap, which is resisted by the viscosity of the air.