Sensitivity manipulation on micro-machined resonant electrometer toward high resolution and large dynamic range

A micro-resonant electrometer with the scheme of sensitivity manipulation is proposed to realize the high resolution and large dynamic range based on a mechanical resonator and actuator. As the key sensing element, the double-ended tuning fork resonator has a quality factor close to 10 000 and low motional resistance below 0.5 MΩ. Electrical and mechanical nonlinear features of the resonator are investigated. The charge sensing functionality based on the axial strain modulation scheme is calibrated with a high resolution of 2.6 fC under 0.46 ppm frequency fluctuation. With the manipulation, the sensitivity is linearized from quadratic and further decreased to extend the dynamic range by 358.47% up to 12.38 pC. Meanwhile, the frequency fluctuation is also stabilized under 70 mHz to enhance the short-term stability of the sensor.