Shell-in-Shell (SiS): 3D Shell Resonator with 3D Conformal Shell Electrodes

This paper reports the design, fabrication technology and initial testing results of an all fused-silica 3D shell (hemispherical) resonator and capacitive drive/sense electrodes made from a second shell, for use in high-performance gyroscopes. A single fused-silica shell is patterned to form multiple electrodes that follow the curvature of the shell resonator. 10 mm diameter Shell resonator is then integrated inside a larger Shell electrode (SiS). Our approach enables, for the first time, the fabrication of curved electrodes at the micro-scale. The SiS device provides large overlap area and nearly uniform gap with large capacitance for better frequency tuning capability, reduced operating voltages, improved capacitive sensitivity and reduced temperature sensitivity as compared to other electrode architectures. Successful fabrication and testing of two prototype SiS devices are demonstrated. Quality factor as high as of 0.4 Million and frequency split as low as 1.3 Hz is obtained at operating frequency of ~ 6000 Hz.