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Experimental Characterization of Electrostatic MEMS Resonators for Sensing Applications
Alattar, Basil Yousef Ahmad
Alattar, Basil Yousef Ahmad
Date
2023-04
Author
Advisor
Type
Thesis
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Description
A Master of Science thesis in Mechatronics Engineering by Basil Yousef Ahmad Alattar entitled, “Experimental Characterization of Electrostatic MEMS Resonators for Sensing Applications”, submitted in April 2023. Thesis advisor is Dr. Mehdi Ghommem. Soft copy is available (Thesis, Completion Certificate, Approval Signatures, and AUS Archives Consent Form).
Abstract
In this Thesis, we present an experimental technique to detect the onset of bifurcation and measure the extent of hysteresis in electrostatic MEMS resonators. The device- under-test comprises a microcantilever beam actuated via a side electrode placed inside a vacuum chamber to control the squeeze-film damping. The beam vibrations result in varying the resonator’s capacitance, therefore inducing a current that can be measured and used for characterization and performance analysis. The motion-induced current is measured, and its harmonics are extracted using a lock-in amplifier. Locking on the third harmonic of the induced current enables us to bypass parasitic capacitance and extract a signal directly related to the resonator motions. We show that this signal can be used to investigate the nonlinear dynamic behaviour of MEMS resonators undergoing large motions. Specifically, our experiments demonstrate our technique's ability to detect various bifurcations, to track the onset of hysteresis, and to measure the hysteresis bandwidth. We also use our technique to analyse the quantitative relationships between the actuation voltage, the location of the bifurcation point, and the hysteretic bandwidth. We show that our technique can be used to generate the calibration curves for inertial MEMS sensors. Finally, we compare the use of two measurement techniques for the nonlinear analysis of electrostatic MEMS resonators: optical vibrometry and motion-induced current. We demonstrate the capability of the two approaches to detect nonlinear features in the motions of the resonator when subjected to high excitation voltages. We also show that the measurements obtained from both techniques for the onset of multivaluedness, cyclic-fold bifurcations, and hysteresis are in close agreement.