Monolithic capacitive transducer

Abstract

A capacitive transducer includes a substrate having a first surface and a second surface. The first surface of the substrate defines a first plane. The substrate has a cavity with an interior peripheral edge. The cavity extends between the first surface and the second surface. A body is provided that has an exterior peripheral edge. The body is parallel to the first plane and at least partially blocking the cavity. The body is connected to the substrate by resilient hinges such that, upon the application of a force, the body moves perpendicular to the first plane. A first set of comb fingers is mounted to the substrate. The first set of comb fingers is connected to a first electrical connection. A second set of comb fingers is mounted to the body and extends past the exterior peripheral edge of the body. The second set of comb fingers is connected to a second electrical connection that is isolated from the first connection. The first set of comb fingers and the second set of comb finger are interdigitated such that as the body moves, the first set of comb fingers and the second set of comb finger maintain a relative spacing. The first set of comb fingers and the second set of comb fingers define a capacitance. The capacitance is related to the relative position of the first set of comb drive fingers and the second set of comb drive fingers.