SLIDE FILM DAMPING IN LATERALLY DRIVEN MICROSTRUCTURES

Slide film damping occurs when two parallel plates are in relative tan gential motion. Viscous energy dissipation in the fluid between the tw o plates becomes a representative damping mechanism in laterally drive n microdevices. In this paper, we investigate the slide film damping b oth theoretically and experimentally. A new physical model has been pr oposed for the characterization of slide film damping. Dynamic charact eristics of a fluid film have been described in terms of velocity prof iles, damping mechanisms, and levels of viscous energy dissipation. Si mplified analytical damping formulae have been developed for practical Q estimation. The theoretical Q compares well with the experimental Q . Data reported by previous investigators are also analyzed and compar ed with the Q value estimated in the present study. It is concluded th at our theoretical model offers simple and reasonably good quantitativ e prediction of Q. Possible sources of error in the theoretical Q pred iction are discussed. The effects of fluid-film thickness and microstr ucture geometry on Q are investigated, so that the results can be used in the damping design for laterally driven microtransducers.