Damping Ratio Analysis of a Silicon Capacitive Micromechanical Accelerometer
- 1 Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, China
- 2 Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, China
- 3 Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, China
- 4 Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, China
- 5 Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang, China
Abstract
In most MEMS devices, the moving micro-structures are surrounded by air which significantly affects their dynamics behaviors. The correct prediction of the squeeze-film air damping ratio is essential in MEMS (Micro-Electro-Mechanical System) devices design. In the paper, a static test is proposed to measure the squeeze-film air damping ratios of capacitive MEMS accelerometer under different pressures. The unsealed chip of capacitive accelerometer is placed in vacuum extraction equipment and an open loop circuit is developed to apply step signal in the test. By charging the pressure and measuring the overshoot M p and the settling time t s from the time response of the system, the damping ratio ξ under different pressures can be calculated. Finite element method (FEM) based on the modified Reynolds equation is utilized to simulate the transient response of the micro-structure. Good correlation between experiment and FEM analysis is obtained. The proposed static test in this paper provides a new method to more easily measure the dynamic performances of micro-structures under various pressures.
- Newell, W. (1968) Miniaturization of Tuning Forks. Science, 161, 1320-1326. https://doi.org/10.1126/science.161.3848.1320
- Chen, C.-S. and Kuo, W.-J. (2003) Squeeze and Viscous Dampings in Micro Electrostatic Comb Drives. Sensors and Actuators A, 107, 193-203.
- Mehner, I., Billep, D., et al. (1998) Simulation of Gas Damping in Microstructures with Nontrivial Geometries. Proceedings of the 11th Annual International Workshop on Micro Mechanical Systems, Heidelberg, 25-29 January 1998, 172-177. https://doi.org/10.1109/memsys.1998.659749
- Hutcherson, S.M. (2004) Theoretical and Numerical Studies of the Air Damping of Micro-Resonators in the Non-Continuum Regime. Dissertation, G. W. Woodru School of Mechanical Engineering, Georgia Institute of Technology.
- Moeenfard, H. (2015) Analytical Modeling of Squeeze Film Damping in Dual Axis Torsion Microactuators. Surface Review and Letters, 22, 1550006-1-1550006-8. https://doi.org/10.1142/S0218625X15500067
- Brugdorfer, A. (1959) The Influence of the Molecular Mean Free Path on the Performance of Hydrodynamic Gas Lubricated Bearings. Journal of Basic Engineering, 81, 94-99.
- Hsia, Y.T. and Domoto, G.A. (1983) An Experimental Investigation of Molecular Rarefaction Effects in Gas Lubricated Bearings at Ultra Low Clearance. Journal of Lubrication Technology, 105, 130-130.
- Mitsuya, Y. (1993) Modified Reynolds Equation for Ultra-Thin Film Gas Lubrication Using 1.5-Order Slip-Flow Model and Considering Surface Accommodation Coefficient. Journal of Tribology, 115, 289-294. https://doi.org/10.1115/1.2921004
- Tan, Y., Lv, Y. and Pan, Z. (2012) The Analysis and Simulation of Squeeze Film Damping Characteristics of Low Air Pressure MEMS Accelerometer. IEE International Conference on Oxide Materials for Electronic Engineering, 351-354.
- Zhou, Z. and Wang, X. (2011) Analysis of Squeeze-Film Air Damping of Thick Perforated Plate in MEMS Device. Proceedings of the 6th IEEE International Conference on Nana/Micro Engineering and Molecular Systems, Kaohsiung, 20-23 February 2011, 131-133. https://doi.org/10.1109/nems.2011.6017312
- Kim, E.-S., Cho, Y.-H. and Kim, M.-U. (1999) Effect of Holes and Edges on the Squeeze Film Damping of Perforated Micromechanical Structures. 12th IEEE International Conference on Micro Electro Mechanical Systems, Orlando, FL, 21 January 1999, 296-301.
- Darling, R., Hivick, C. and Xu, J. (1998) Compact Analytical Modeling of Squeeze Film Damping with Arbitrary Venting Conditions Using a Greens Function Approach. Sensors and Actuators A, 70, 32-41.