Prediction of Squeeze-Film Damping Effects on a Rectangular Micro-Plate in the Free Molecule Regime Due to Modified Reynolds Equation

Damping in microelectromechanical systems (MEMS) is critical for device design, simulation and material properties. Oscillating MEMS devices include a plate like structure that oscillates out of plane and generally normal to fixed substrate. These structures have a trapped film between the structure and the fixed substrate either by design or by partial vacuum packing. Thetrapped air behaves as squeeze-film which results from the reciprocal normal movement of two parallel solids. This paper proposes prediction of squeeze-film damping effects on a rectangular micro-plate in the free molecule regime due to modified Reynolds equation. The validity of the free molecule regime depends on the Knudsen number (Kn), which is haracterized as the ratio of the mean free path of the gas molecule to the characteristic length of the flow. Moreover, the experimental results are compared to analytical models for calculating the damping coefficient in different pressure. The final results exhibit that the proposed experimental results are reliable for simulating a rectangular micro-plate in the free molecule regime. In addition, results demonstrate that the present model has a good agreement with analytical models for receiving damping coefficient of the micro-structure.

Keywords:

Micro-Electro-Mechanical Systems (MEMS) , Squeeze-film damping , Reynoldsequation , Analytical models , micro-plate , Damping coefficient