Squeezed film damping measurements on a parallel-plate MEMS in the free molecule regime

Abstract

This paper provides experimental validation of the predictions by two recent models for squeezed film damping in the free molecule regime. Measurements were carried out using a parallel-plate microstructure with a 2.29 νm gap operated at pressures from 105 to 101 Pa (corresponding to Knudsen numbers from 0.03 to 300). Experiments are in good agreement with the modelling based on molecular dynamics at Knudsen numbers over 10. The result also indicates that modelling based on the modified Reynolds equation including inertia effects underestimates the damping due to end effects; however, it correctly predicts the trend for lower Knudsen numbers. © 2009 IOP Publishing Ltd.