Displacement amplification of piezoelectric microactuators with a micromachined leverage unit

One of the so-called Aero-MEMS applications is the drag reduction on airfoils by using an array of dedicated microactuators. When applying active wave cancellation principles in thin transitional boundary layers, these actuators need to exhibit relatively large stroke at relatively high operational frequencies. For this purpose, a novel micromachined mechanical amplification unit for increasing the stroke of piezoelectric microactuators up to high frequencies is presented in this paper. The mechanical lever is provided by a silicon membrane, sliced in a cake-like fashion. The fabrication and assembly process as well as results of dynamic simulations and experimental measurements are reported. For frequencies from quasi-static up to 15 kHz and for varying spacer positions, an amplification ratio of 5–13 is obtained when comparing displacements at the piezoelement and at the lever tip. Results from finite element simulations were found to be in good agreement with experiments. Finally, the application of these microactuators on airfoils for manipulating the transition point between laminar and turbulent flow conditions is discussed.