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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. [ABSTRACT FROM AUTHOR]

In this work, amplification units made of robust metallic nickel titanium (NiTi) and single crystal silicon are compared and evaluated for the application in miniaturized piezoelectric actuators for flow control purposes. The amplification mechanism with a sliced membrane structure is based on a mechanical lever in order to amplify the low piezoelectrically induced deformation. Therefore, an enhanced output stroke can be provided up to high frequencies. The different membrane fabrication processes using laser ablation for the NiTi alloy and deep reactive ion etching for the silicon substrate, as well as the results of finite element simulations and experimental measurements are reported. An amplification factor of 9 has been achieved for an optimized load transmission point position. The dynamic response shows a quality factor of 25 and 494 at the first fundamental mode for NiTi and silicon membranes, respectively. Compared to silicon, NiTi shows enhanced properties against failure and facilitates the integration process. [ABSTRACT FROM AUTHOR]