High-resolution and large dynamic range electrometer with adjustable sensitivity based on micro resonator and electrostatic actuator

This paper reports a novel resonant electrometer with resolution of sub-1 femto coulomb, in which scheme of adjustable sensitivity is firstly proposed to realize both high resolution and large dynamic range. A double-ended tuning fork resonator is utilized as the charge sensing element, and an electrostatic comb-drive actuator is used to adjust sensitivity. The maximum sensitivity of the electrometer was found to be 1.03×10
^-2
Hz/fC
²
. The adjustable capacitance will increase 9.7 fF when 40 V DC voltage is added on the electrostatic actuator. As a result, the sensitivity can be adjusted by 91.6%. Electrostatic spring softening and nonlinear feature of the resonator are also investigated.