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This paper provides the first experimental validation of the predictions by two recently introduced models for free molecule squeezed film damping. Measurements were carried out using a parallel-plate microstructure with a 2.29 µm gap operated at air pressures from 105 down to 101 Pa (corresponding to Knudsen numbers from 0.03 to 300). Experiments are in good agreement with the modeling based on molecular dynamics at low pressures. The results also indicate that modeling based on the modified Reynolds equation including inertia effects underestimates the damping due to end effects, but correctly predicts the trend at lower Knudsen numbers reaching into the transitional regime.

Squeeze-film damping is highly inadequate in low-pressure systems or in systems where air pressure and/or gap dimensions are poorly defined. Input shaping has been used to circumvent the oscillations typically associated with under-damped mass-spring-damper systems and drastically decrease the settling time. The proposed method does not rely on feedback but solely on the system dynamics. The required input signal is derived analytically from the differential equation describing the system. The resulting device response is simulated and experimentally verified on an electrostatically actuated microstructure. Settling occurs even faster than for an equivalent critically damped system.