Frequency dependent fluid damping of micro/nano flexural resonators: Experiment, model and analysis

This research systematically investigates the fluid damping for micromachined beam-type resonators with high resonant frequencies. The work is aimed to find a general fluid damping law which can quantitatively be used as a design tool for the resonance-based micro sensors by accurately predicting the quality factor for resonators operated in air or liquid. Micro-cantilevers with different dimensions are fabricated and tested in order to extract the damping characteristics. Combined with dimensional analysis, a novel linear fluid damping model is proposed, considering the effects from both device's dimension and the resonant frequency. Further by numerical analysis, the model is generalized to resonators with differently shaped cross-sections. Also the proposed fluid damping model provides an attractive way to use simple beam-type resonators as fluid viscosity sensors and air pressure sensors.