A micromechanical structure eliminating lateral effect of silicon accelerometer

A novel two-mass micromechanical structure for a silicon accelerometer is described. In this structure, each mass is attached to the rim by two beams and a fifth beam bridges the two masses at the central area of the structure. An acceleration normal to the device plane can bring about significant stress in the central beam area while any lateral acceleration in a direction in the device plane has very little effect on the stress to the first order of approximation. As the stresses in the central beam area are of a single sign and change very little on position, four piezoresistors can be located on the central beam area to form a Wheatstone bridge or a single-element Hall-type strain gauge can be used to sense the normal acceleration with little interference by lateral accelerations. Preliminary results on the device are presented.<
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