A New Free Molecular Model for Squeeze-Film Damping of Flexible Microbeam in Low Vacuum

Predicting air damping is crucial in the design of high Q microelectromechanical systems. In the past, squeezefilm damping in low vacuum is usually estimated using the free molecular model proposed by Bao (J.Micromech.Microeng, 2002,12: 341-346). However, the Bao's model neglected the deflection of the plate; thus the model is only suitable for rigid plate. This paper presents a new free molecular model to describe squeeze-film damping of flexible microbeam in low vacuum. An energy-transfer model is used to study the effect of a moving microbeam on changing the kinetic energy of the gas molecules. Compared with the previous models, the present model accounts for the flexibility of microbeam based on using the modal analysis techniques. The accuracy of the present model is verified by comparing its results with the experimental results available in the literature.