Design of an integrated piezoelectric micro-flapper based on bionic principles

We present a novel micromachined piezoelectric actuator structure, which effects directed large area fluid transport on chip-level and is supposed to be used for venting or cooling applications. The design of the actuator is inspired by the bionic principle of fish locomotion and the flight characteristics of small insects. An intricate superposition of translatory and rotatory motion of a fin- or wing-like structure leads to an undulatory motion of the mechanical structure. This, in turn, induces vortices in the surrounding fluid, which overlap and eventually form a chain of vortices (so-called wake) that generates a strong axial jet stream pointing away from the vibrating flap. The momentum transfer effected thereby on the fluid results in directed flow of mass and convective heat. For the technological realization of this concept, we selected an existing industrial piezoelectric thin film process as material basis and designed a twin-cantilever actuator element with large lateral areas featuring large deflections. Coupled energy domain (“multiphysics”) FEM analysis has been carried out with a view to specifying the over-all geometry and the extension, location, and shape of the electrodes. The bundle of design variants derived from the theoretical analysis and the results of the finite element calculations are currently on their way to be cast in hardware.