THE ACCURATE MEASUREMENT OF A MICROMECHANICAL FORCE USING FORCE-SENSITIVE CAPACITANCES

A sensor for the precise and accurate measurement of micromechanical f orces is presented. The sensor is based on the capacitive detection of force-induced deflection of a microstructure and integrated charge re adout. The mechanical performance of the sensor is evaluated and verif ied with experiments. The structure has been designed to enable the se paration of the force-to-deflection and deflection measurements in ord er to result in a sensor structure in which the response is linear wit h force and little affected by fringe fields. The sensor is 0.25 mm(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/mu N, and a resolution that correspon ds to a capacitance variation of 2 fF.