Handbook of Silicon Based MEMS Materials and Technologies

Chapter Fourteen. Gas Damping in Vibrating MEMS Structures

14.1. Introduction

MEMS structures are surrounded usually by gas, e.g., air, and when they move or vibrate, the structures interact with the surrounding gas. The most dominant effect of the gas is the damping force acting on the vibrating structure, but also spring forces and inertial forces may be important for the operation of the MEMS device. MEMS devices affected by the gas interaction are many: accelerometers [1–3], torsion micromirrors [4–6], optical and capacitive switches [7–11], and generally various resonator structures [12–14].

Generally, the gas motion is a 3D phenomenon and not very easy to analyze. Fortunately, the gas effects are the strongest when the flow takes place ...