Interdigitated single crystal piezoelectric actuator

Abstract

Piezoelectric actuators are used as critical units or elements of various electromechanical systems. In this paper, we propose a novel piezoelectric actuator cantilever with double interdigitated electrode patterns. We investigate the possibility of both flexural and longitudinal actuation capabilities of the double interdigitated electrode patterns applied on a piezoelectric cantilever structure. This monomorph structure has the interdigitated electrode patterns top and bottom. The structure also uses single-crystal relaxor ferroelectric material. We separately pattern interdigitated electrodes on the top and bottom surfaces of a PMN-PT single crystal cantilever beam. The interdigitated electrode design on a surface of the cantilever beam results in an electric field gradient. This results in a flapping actuation. Previously, we showed that the vertical field component induced by the interdigitated electrode is dominant over the horizontal component under input bias voltage, and generates subsequent contraction of the surface along the axial direction after poling. In this paper, we show that a contraction on the top surface and an elongation on the bottom leads to upward bending motion because of the differential contraction along the thickness induced by the interdigitated electrode pattern. Similarly, an equivalent elongation on the top and bottom surfaces is shown to lead to longitudinal motion in the double interdigitated electrode sample.