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. >

[1]  M. R. Wolffenbuttel,et al.  Reactive ion etching (RIE) techniques for micromachining applications , 1994 .

[2]  S. Terry,et al.  Second-order effects in self-testable accelerometers , 1990, IEEE 4th Technical Digest on Solid-State Sensor and Actuator Workshop.

[3]  K. Wise,et al.  A 1024-element high-performance silicon tactile imager , 1988 .

[4]  Reinoud F. Wolffenbuttel,et al.  The read-out characteristics of an integrated charge amplifier for potentially broad-field applications , 1992, [Proceedings] 1992 IEEE International Symposium on Circuits and Systems.