Design Simulations of MEMS Micropump by 3D Fluid-Structure Interaction Analysis J. Johari * and B. Y. Majlis ** * Faculty of Electrical Engineering, Universiti Teknologi MARA Selangor, Malaysia, julia893@salam.uitm.edu.my ** Institute of Microengineering and Nanoelectronics, IMEN Universiti Kebangsaan Malaysia, Selangor, Malaysia, burhan@vlsi.eng.ukm.my ABSTRACT In this study, a three-way approach in designing a piezoelectrically actuated valveless micropump based on MEMS bulk micromachining fabrication process has been presented. The designed piezoelectrically actuated valveless micropump (PAVM) is analyzed using the fluid-structure interaction method to accurately predict the working behavior of the micropump based on the fluid, structural and piezoelectric equations. The fluid-structure dynamic effects should be taken into account in detail, since it is not enough to understand the intended functions individually due to the increasing demands for accuracy. In view of that, a coupled-field electro-mechanical-fluidic model of the PAVM has been simulated using MemFSI TM , a fluid- structure interaction (FSI) solver available in CoventorWare TM software package. Results obtained from the simulations are compared with analytical studies for verification purposes. Keywords: piezoelectrically actuated valveless micropump, fluid-structure interaction 1 INTRODUCTION Micropumps are essential microfludics devices. The applications of such devices range from controlling and delivering tiny amounts of fluids from one point to another on a microfluidics system. Given the market potential for applications in microfluidics and drug delivery especially, micropumps are of considerable interest to researchers and industrial consumptions [1, 2]. Van de Pol and Van Lintel presented the first silicon micropump based on piezoelectric or thermopneumatic actuation of a thin membrane. Many micropumps have since been developed in the last few years based on different actuating principles and fabrication technologies. However, pump output characteristics and affecting factors have not been investigated thoroughly [3, 4]. Mechanical reciprocating displacement micropumps with vibrating membrane have generated the most interest among other type of micropumps. Even though various actuating principles of membrane micropumps have been developed such as piezoelectric, pneumatic, thermal, pneumatic, electrostatic, and electromagnetic, the piezoelectric type has been widely used. Because piezoelectrically actuated valveless micropump (PAVM) has simple structure and no internal moving parts, there is less risk of clogging the valves, when it pumps fluid containing particles. Also, they can respond quickly and have obvious advantages over other kinds of micropumps. See the review by Gong et al for more details [5]. Figure 1 shows the working principle of a PAVM, driven by a piezoelectric patch bonded to a diaphragm, which forces fluid through a small chamber. (a) Diaphragm bends up (b) Diaphragm bends down Figure 1: The working principle of a PAVM. In parallel flow, the flow rate through the diffuser is less than that through the diffuser because the resistance in the nozzle is higher than the resistance in the diffuser. Piezoelectric actuator Diffuser Nozzle Diffuser Piezoelectric actuator Nozzle Net flow direction NSTI-Nanotech 2010, www.nsti.org, ISBN 978-1-4398-3402-2 Vol. 2, 2010 677