Authors: K.M. Harish, B.J. Gallacher, J.S. Burdess and J.A. Neasham
Affilation: University of Newcastle upon Tyne, United Kingdom
Pages: 25 - 28
Keywords: parametric, resonance, MEMS gyroscopes, harmonic balance
This paper reports experimental results for a parametrically excited micro-ring resonator. Actuation and sensing are performed electrostatically thus making the scheme suitable for many vibratory sensors. The equation of motion for the electrostatically actuated MEMS ring resonator is shown to be of the form of an inhomogeneous Hill's equation. The electrostatic force contains a stiffness modulating term which, when modulated at a frequency near twice a natural frequency of the resonator, results in parametric resonance. Frequency sweeps, centered around twice the measured natural frequency of the device, were performed at various voltages and the parametric resonance was observed electrically at half the excitation frequency. This data was used to map the 'boundary curve’, demarcating the regions of stability and instability and was compared with theoretical predictions. Ultimately, the parametric excitation will be combined with harmonic forcing in order to increase the Q-factor of the ring resonator by at least two orders of magnitude. It is proposed that this excitation method will vastly reduce electrical “feed-through”. Two important applications benefiting from this excitation scheme will be in the area of near inertial grade MEMS gyroscopes and bio-MEMS.
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