Pressure-dependent damping characteristics of microsilicon beam resonators for different resonant modes

This paper is to investigate (experimentally and model-based) the resonant-mode dependence of microcantilevers\´ damping characteristics and how this dependence changes for different pressure ranges: air pressure (100Torr and higher), high vacuum (~ 1mTorr) and pressures in between. In air pressure, we focus on the damping caused by the fluid drag force. A frequency dependent fluid damping model is proposed and experimentally validated. At high vacuum, thermo-elastic damping (TED) is demonstrated to be the main damping source experimentally, for frequency range from 10Khz to 2MHz and up to 6 resonant modes. By proper design we are able to tell that the "effective" viscous damping is dominant in the transition pressure regime