Investigation of a complete squeeze-film damping model for MEMS devices

Abstract

Dynamic performance has long been critical for micro-electro-mechanical system (MEMS) devices and is significantly affected by damping. Different structural vibration conditions lead to different damping effects, including border and amplitude effects, which represent the effect of gas flowing around a complicated boundary of a moving plate and the effect of a large vibration amplitude, respectively. Conventional models still lack a complete understanding of damping and cannot offer a reasonably good estimate of the damping coefficient for a case with both effects. Expensive efforts have been undertaken to consider these two effects, yet a complete model has remained elusive. This paper investigates the dynamic performance of vibrated structures via theoretical and numerical methods simultaneously, establishing a complete model in consideration of both effects in which the analytical expression is given, and demonstrates a deviation of at least threefold lower than current studies by simulation and experimental results. This complete model is proven to successfully characterize the squeeze-film damping and dynamic performance of oscillators under comprehensive conditions. Moreover, a series of simulation models with different dimensions and vibration statuses are introduced to obtain a quick-calculating factor of the damping coefficient, thus offering a previously unattainable damping design guide for MEMS devices.

Design and Implementation of Low-Voltage Tunable Capacitive Micro-Machined Transducers (CMUT) for Portable Applications

“…Air squeeze-film damping is produced when a DC voltage is combined with an AC signal across the electrodes of the CMUT, which leads to the membrane (piston) vibrating at the frequency of the AC excitation [ 23 ]. Squeeze-film damping is dominant in MEMS devices, and its influence becomes significant with decreasing device dimensions [ 24 ] as well as with lower resonance frequency devices [ 25 , 26 ]. A thin film-damping boundary condition was applied on the bottom side of the vibrating-membrane model, with the distance to the base selected as the electrode gap.…”

Built-In Packaging for Single Terminal Devices

“…The actuation voltage is limited by the function generator. Although decreasing the air gap between the resonator and actuation electrode increases the electrostatic force, it could introduce additional squeezed film damping, , in Equation (4) [ 50 ]. …”

Thermoelastic damping in MEMS gyroscopes at high frequencies

“…However, to the authors' knowledge, there has been no exhaustive research on the damping of high-frequency modes in MEMS gyroscopes. Known damping mechanisms that can contribute to the quality factors of MEMS resonators are gas damping, thermoelastic damping (TED), anchor losses, surface losses, material losses and Akhiezer damping [8][9][10][11][12][13][14][15][16] . The first three are usually considered as the dominant mechanisms in polysilicon MEMS resonators.…”