The accurate measurement of a micromechanical force using force-sensitive capacitances

A sensor for the precise and accurate measurement of micromechanical forces is presented. The sensor is based on the capacitive detection of force-induced deflection of a microstructure and integrated charge readout. The mechanical performance of the sensor is evaluated and verified with experiments. The structure has been designed to enable the separation of the force-to-deflection and deflection measurements in order to result in a sensor structure in which the response is linear with force and little affected by fringe fields. The sensor is 0.25 mm/sup 2/ in size and has a force range of 0.2 mN, a zero-force capacitance of 0.5 pF, a sensitivity of 1-5 fF//spl mu/N, and a resolution that corresponds to a capacitance variation of 2 fF.<
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