Structural design of torsional micro-gyroscope having robust drive and sense modes

This paper reports a structural design of a torsional micro-gyroscope having robust drive and sense modes. The structure achieves robustness by utilizing dynamic amplification of torsional vibrations in both the drive and sense resonators. The frequency response of both the drive and sense resonators, which are 2-degree-of-freedom (DOF) resonators, has two resonance peaks and a flat region between the peaks, where the amplitude is less sensitive to the ambient damping resulting in the robust drive and sense modes. The flat regions of the drive and sense modes are designed to overlap, which helps in reducing the effects of change in geometry and material properties of the device, due to fabrication imperfections, on the device performance. The robust drive and sense modes also relax the requirement of a closed loop circuit for either actuating the device at resonance or sensing the capacitance change at resonance and hence, eventually reduce the circuit complexity. The device is modeled using the concepts of anti-resonance and zero-phase frequencies. The fabrication of the device is carried out using an SU-8 based ultraviolet-lithographie, galvanoformung, abformung (UV-LIGA) process. The developed prototype is tested for amplitude and phase spectral responses using a laser Doppler vibrometer (LDV).