What happens turning a 250-μm-thin piezo-stack sideways?

Abstract

Usually when piezoelectric membrane actuators are mentioned, one classically thinks of a passive membrane with a piezoelectric actuator on top. In this paper omitting the passive membrane will be suggested. Therefore, the piezoelectric actuator will not be commonly designed as plate capacitor structure, such as that the piezoelectric material sitting between two plate electrodes. Rather will the actuation be caused by structured surface electrodes on only one side of the piezoelectric material, leaving the opposite side free of potential. Several surface electrode designs, starting with interdigital parallel structures, known from surface acoustic wave transducers, spiral and ring structures, ending with star-shaped structures, are tested. The main advantage of this actuation principle is that with the varying electrode design it became possible to also generate an upward movement, i.e., in the direction of electrode side of the membrane. This upward movement has not been achieved with any piezoelectric membrane actuator so far.

Thin PZT materials for large deformation interdigitated acutators: Simulation & experimental validation

“…The deformation is directed downwards (a concave with respect to the electrodes side) and this is consistent with what is found in literature for PZT thin films and 250 µm thick PZT materials [1,2,3,4]. The deformation has a maximum value of -3.9 µm at the center of the actuator.…”

“…One of the most commonly used piezoelectric materials is the Lead-Zirconate-Titanate (PZT) family which are suited for actuators due to their large piezoelectric coefficients (d ij ). In literature, the functionality of piezoelectric actuators driven by interdigitated electrodes has been demonstrated for PZT thin films [1,2] and for 250 µm thick PZT substrates [3,4].…”

Piezoelectric Bulk Material for the Fabrication of Membrane Actuators Using Surface Electrodes for Actuation

“…Those electrode layouts were polarized and characterized. The most uniform symmetric deformation was obtained with the ring layout, which showed a downward deflection diametric to the electrode surface [1,3]. Those deflections were comparable to those obtained with common piezoelectric membrane actuators, capacitor or stack assemblies, of the same dimensions.…”