Dynamic characteristics of a micro-mechanical-resonator with squeeze film damping

Electrostatically actuated micromechanical resonators with advantages of high frequency, low-power consumption and small size are widely used in chemical sensors and sensors of biological species, these sensors work in air or liquid. The air damping as surface effects and the cubic nonlinear static electrical stiffness can significantly affect the dynamic response characteristics of a micromechanical resonator. Here, via the squeeze-film damping theory, the effects of air damping caused by ambient pressure during free vibration and cubic nonlinear static electrical stiffness on the patterns of movement and response performance of a mirco beam fixed at both ends were investigated in detail. The relationships between the dynamic characteristics of the resonator and ambient pressure as well as nonlinear static electrical stiffness were found. The results indicated that the resonance frequencies of the micromechanical resonator increase with increase in ambient pressure, while the vibration amplitudes and the resonance drift decline with increase in ambient pressure; the cubic nonlinear static electrical stiffness makes the resonators exhibit softening or hardening nonlinear characteristics, they can not be ignored in amplitude-frequency curves of the resonaters' small amplitude vibration. ©, 2015, Chinese Vibration Engineering Society. All right reserved.