Robust Superelastic, Metallic Amplification Unit for Piezoelectric Microactuators C. Bolzmacher* a , K. Bauer a , U. Schmid b , M. Hafez c , H. Seidel d a EADS Innovation Works Germany, 81663 Munich, Germany; b Vienna University of Technology, Institute of Sensor and Actuator Systems, Department for Microsystems Technology, 1040 Vienna, Austria; c CEA LIST, Sensory Interfaces Laboratory, 92265 Fontenay-aux-Roses, France; d Saarland University, Chair of Micromechanics, Microfluidics/Microactuators, 66041 Saarbruecken, Germany; ABSTRACT In this work, a robust metallic amplification unit for piezoelectric microactuators is presented. The mechanism which is implemented with a sliced membrane structure made from a superelastic nickel titanium alloy is based on a mechanical lever in order to amplify the small piezoelectrically induced deformation. Therefore, increased stroke can be provided up to high frequencies. The fabrication process using laser ablation, the assembly process, the static and dynamic simulations and experimental measurements are reported. An amplification factor of 9 has been achieved for a specific load transmission point position. The dynamic response shows a quality factor of 25 at 11.97 kHz for the first mode. Compared to silicon, nickel titanium shows enhanced properties against failure and facilitates the integration process. Keywords: piezoelectric microactuator, amplification unit, superelastic NiTi alloy 1. INTRODUCTION The main source of drag on an airplane is caused by viscous drag in the turbulent boundary layer. In contrast to the turbulent boundary layer, the drag caused by the laminar boundary layer is only one tenth at equal Reynolds numbers [1]. Hence, a significant amount of drag reduction on aircraft wings could be achieved by delaying the laminar-turbulent transition. The manipulation of instabilities using small actuators may stabilize the boundary layer to some extent. An application example is the delay of laminar-turbulent transition, applying active wave cancellation by the superimposition of artificially generated counter waves [2,3]. Actuators for that purpose are required to provide high stroke amplitudes and relatively high operational frequencies between 1 kHz and 25 kHz when operated at high Reynolds numbers as encountered on airfoils at cruise conditions. In addition, low overall power consumption is mandatory. MEMS-based actuators are the best candidates to fulfill these requirements [4]. Many actuation technologies have been proposed for MEMS devices in fluidic applications, including piezoelectric [5], electro-static [6], thermo pneumatic [7], electrochemical [8], shape memory alloy [9], and electromagnetic [10,11] principles. For the application in high-speed aerodynamics requiring a large frequency range, electrostatic and electromagnetic actuation principles do not provide enough stroke amplitude. Electrochemical, thermopneumatic, and shape memory alloy based devices work well in lower frequency domains. Piezoelectrics provide only small inherent stroke amplitudes, but cover a very large frequency range requested for high-speed aerodynamics. To reach larger displacements, external amplification mechanisms can be used to convert the high-force, limited stroke output into an increased stroke [12]. Furthermore, enough reserves can be provided to compensate varying load conditions during flight. *Christian.bolzmacher@eads.net; phone +49 89 607 28938; fax +49 89 607 24001; www.eads.com Smart Sensors, Actuators, and MEMS IV, edited by Ulrich Schmid, Carles Cané, Herbert Shea Proc. of SPIE Vol. 7362, 73620M · © 2009 SPIE · CCC code: 0277-786X/09/$18 · doi: 10.1117/12.821727 Proc. of SPIE Vol. 7362 73620M-1