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

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.