A new silicon triaxial resonant micro-accelerometer

We present the design, fabrication, and testing of a new silicon triaxial resonant micro-accelerometer. It is characterized by a biaxial planar resonant micro-accelerometer and a vertical resonant micro-accelerometer based on electrostatic stiffness. The biaxial resonant micro-accelerometer, which is decoupled in two sensitive directions by four pairs of decoupling beams, senses the acceleration by two pairs of tuning fork resonators with an excellent linearity and uniformity. The vertical resonant micro-accelerometer, where the sensing movement of the accelerometer is decoupled with oscillation of the plane resonators, senses the acceleration by electrostatic stiffness. Six analog self-oscillation circuits and a digital frequency measurement circuit based on FPGA are designed to control the triaxial resonant micro-accelerometer. The standard three-mask Deep Dry Silicon on Glass (DDSOG) process is used for fabrication of the triaxial decoupled resonant micro-accelerometer. Experimental results demonstrate a mechanical sensitivity of 52.57Hz/g(x-axis), 51.64 Hz/g(y-axis) and 31.65 Hz/g(z-axis) and a bias stability of 0.294mg(x-axis), 0.278mg(y-axis) and 0.727mg(z-axis).