Radial Field Piezoelectric Diaphragms

Abstract

A series of active piezoelectric diaphragms were fabricated and patterned with several geometrically defined Inter-Circulating Electrodes “ICE” and Interdigitated Ring Electrodes “IRE”. When a voltage potential is applied to the electrodes, the result is a radially distributed electric field that mechanically strains the piezo-ceramic along the Z-axis (perpendicular to the applied electric field). Unlike piezoelectric bender actuators, the Radial Field Diaphragm (RFD) strains concentrically yet affords high displacements without any appreciable XY-strain beyond its perimeter, as both the radial and tangential strain field approach zero at the boundary independent of actuator movement. The result is a Z-axis deflection that has a conical profile. This article covers the fabrication and characterization of these RFDs as a function of poling field strength, ceramic thickness and geometry, electrode type, line spacing, surface topography, the resulting localized strain field and displacement as a function of applied voltage at low frequencies. The unique features of these RFDs are the ability to be clamped about their perimeter with little or no change in displacement, the environmentally insulated packaging and a highly repeatable fabrication process that uses commodity materials.