Surface Micro Machined Actuators on Piezoelectric Bulk Material

Abstract

Using circular discs of piezoelectric material an easy adaptation to well-known silicon surface micro machining technologies is possible. Thus, several interdigitated electrodes layouts have been positioned on a planar lead-zirconate-titanate disc via lift off processes. Because of an inhomogeneous electric field distribution the actuated areas on the disc conduct a symmetric deformation of the bulk material without any need of a further passive membrane, as is necessary regarding common piezoelectric membrane actuators. The most interesting deformation was shown by star shaped interdigitated electrodes. It was an overall downward movement (i.e. the side opposite the electrodes) of the actuated area and a center movement in the opposite direction about 25% of the downward movement. This phenomenon is further investigated, especially with regard to increasing the upward movement. Therefore, the behavior of the actuated area has been more thoroughly tested, using laser vibrometry, speckle imaging and white light interferometry. Based on the thus salvaged data, those actuators have been investigated especially concerning their deformation behavior in various clamping modes either during polarization and/or during actuation.