Sub-10e Charge Resolution for Room Temperature Electrometry

We report a micromachined electrometer with a charge resolution of 7 e/radicHz operating in room temperature and ambient pressure. The electrometer performance is approximately 4 orders of magnitude better than the best commercial instruments. The charge sensing element is comprised of a MEMS resonator functioning as a modulated capacitor, wherein an input DC charge is converted to an AC voltage output. We show that sub-electron resolution at room temperature can be achieved with realistic enhancements in system integration based on the device principles described herein