Abstract
The dynamic behavior of microelectromechanical systems (MEMS) devices is closely related to their energy losses during their operations. As MEMS devices operate at atmospheric pressure, air damping is the dominant factor for energy loss. Therefore, it is very important to study the fluid-structure interaction effect of microstructures to evaluate their dynamic responses, and it is of useful to tune their quality factors to further control their dynamic performances. Firstly, this study presents a review of current research on the mechanisms of dynamic energy dissipation in MEMS devices. Then, this study employs experimental methods to investigate the air damping of micro-cantilevers in free space to validate numerical approach and existing approximate models. Based on the experimental results, the study proposes a modified model which can precisely predict the quality factors of the micro-cantilevers in a free air space. Finally, this study experimentally investigates the effect of hydrodynamic coupling of a micro-cantilever array on the dynamic response of a micro-cantilever. The micro-cantilever array consists of three harmonically driven micro-cantilevers dynamically coupled through air flow. The right cantilever and left cantilever (auxiliary-cantilevers) adjacent to the middle cantilever (operating-cantilever) are exploited to generate hydrodynamic force to change the air damping of operating-cantilever. Thus, the quality factor of operating-cantilever can be controlled by changing the phase and magnitude of excitation force on auxiliary-cantilevers, and varying the gap between auxiliary-cantilevers and operating-cantilever.