Microengineered silicon double-ended tuning fork resonators

Micromachined silicon sensors employing resonant sensing offer many potential performance benefits over alternative piezoresistive and capacitive techniques. Resonant devices are, however inherently more complicated to design and fabricate. This article provides a brief overview of the principles of resonant sensing and describes a design study involving double-ended tuning-fork (DETF) resonant structures that overcome many practical difficulties due to their dynamically balanced design and mode of operation. The optimum mode is a lateral vibration in the plane of the wafer and this paper also reports a simple method for exciting and detecting lateral vibrations without compromising the degree of dynamic balance of the structure. Test devices have been fabricated in single-crystal silicon