Air damping of micro bridge resonator vibrating close to a surface with a moderate distance

The vibration of micro resonators is strongly influenced by the hydrodynamics of the surrounding fluid in the vicinity of a rigid wall. While most prior efforts to model this hydrodynamic loading have focused on squeeze film damping with very narrow gaps, in many practical applications, the resonators vibrate close to a surface with a moderate distance. Two recently developed models which deal with this problem are reviewed. Experiments by using a micro bridge resonator with a big range of gaps are performed at controlled gas pressures, and are compared with predictions from these theoretical models. The unsteady Navier–Stokes model yields the best agreement with experiments. (paper)