Dynamic Performance Improving of MEMS Sensor By Gas Damping Structure

For MEMS sensors with movable planar components, the gas damping structure can be used to reduce the oscillation of sensing structure and tune the quality factor of the dynamic system, furtherly improve the performance of these sensors. This paper deals with the application of two main gas damping structure: parallel plate and perforated plate in MEMS sensors. The dynamic behavior prediction of such two damping structure based on Reynolds´ govern equation has been introduced accordingly to control the dynamic performance of sensing system. The parallel damping plates are the basic structures which are able to reduce vibration and increase the quality factors of micro sensors such as accelerometers and gyroscope and so on. The gas damping effects of parallel plate can be predicted by means of conventional Reynolds´ equation. The perforated damping plates are another structures which can reduce the squeeze-film effects furtherly. Although perforating holes in microstructures can reduce the damping effects caused by horizontal air flow, the air flow escaping through perforated holes adds new viscous resistance. Therefore, the conventional Reynolds´ equation for determining squeeze-film damping effects of non-perforated planar structures is no longer applicable. The modified Reynolds´ equation (MRE) can be employed to analyze gas damping effects of perforated plates for small amplitude vibration.