|AVS 54th International Symposium|
|MEMS and NEMS||Tuesday Sessions|
|Session:||MEMS and NEMS Poster Session|
|Presenter:||L.A. Oropeza-Ramos, University of California, Santa Barbara|
|Authors:||L.A. Oropeza-Ramos, University of California, Santa Barbara
C.B. Burgner, University of California, Santa Barbara
C. Olroyd, University of California, Santa Barbara
K.L. Turner, University of California, Santa Barbara
|Correspondent:||Click to Email|
We present a novel scheme for a robust micro gyroscope which is actuated parametrically and is less sensitive to parameter variations. We experimentally demonstrate that using a parametric resonance based actuator, the drive mode signal has rich dynamic behavior with a large response in a large bandwidth. In this way the system is able to induce oscillations in the sense mode due to Coriolis force, despite that there is a clear disparity on the drive and sense natural frequencies. Thus we propose a scheme that reduces the sensitivity loss due to mismatching in the drive and the sense natural frequencies, which is a common problem in micro gyroscopes based on harmonic oscillators, and also increases significantly the range of frequencies where the gyroscope can operate due to its inherent dynamical properties. Rate table characterization is given. Extensive effort has been applied to gyroscopic structures based on two or more degree of freedom (DOF) harmonic oscillator.1 For the 2 DOF type, the drive and the sense resonant modes are tuned to be equal (or nearly equal) in most cases, in such a way that the output is amplified by the quality factor Q, resulting in high sensitivities. Due to the current fabrication processes, structural asymmetries are inevitably present; therefore matching of frequencies commonly requires external trimming or implementation of control schemes. In this paper we present the realization of a novel Micro Electro Mechanical Gyroscope actuated by a set of noninterdigitated comb fingers which generate a force with time and displacement dependent stiffness coefficients. Thus, parametric resonance excitation amplifies the drive mode response over a wide set of frequencies. In this way, differences in drive and sense natural frequencies do not compromise the sensitivity in 1kHz range. The 2 DOF micro gyroscope is fabricated using the standard SOI process flow and rate table characterization is presented under 50 mTorr pressure. The sensor response is detected with a capacitive readout hybrid wire bonded to the gyroscope on a chip. Our device has demonstrated a scale factor nonlinearity of 0.8% within ±150 °/sec. Thus, in this demonstration the micro gyroscope is robust to parameter variations.
1Yazdi, N., et.al., IEEE Proceedings, Vol.86, No.8, 1998.