THREE DIMENSIONAL DYNAMIC ANALYSIS OF A PIEZOELECTRIC VALVELESS MICROPUMP: EFFECTS OF WORKING FLUID

Coupled structural and fluid flow analysis of a piezoelectric valveless micropump is carried out for liquid transport applications. The valveless micropump consists of trapezoidal prism inlet/outlet elements; the pump chamber, a thin structural layer (Pyrex glass) and a piezoelectric element (PZT-5A), as the actuator. Two-way coupling of forces and displacements between the solid and the liquid domains in the systems are considered where actuator deflection and motion causes fluid flow and vice-versa. Flow contraction and expansion (through the trapezoidal.prism inlet and outlet respectively) generates net fluid flow. The pressure, velocity, flow rate and pump membrane deflections of the micropump are investigated for six different working fluids (acetone, methanol, ethanol, water, and two hypothetical fluids). For the compressible flow formulation, an isothermal equation of state for the working fluid is employed. Three-dimensional governing equations for the flow fields and the structuralpiezoelectric bi-layer membrane motions are considered. Comparison of the pumping characteristics of the micropumps operating with different working fluids can be utilized to optimize the design of MEMS based micropumps in drug delivery and biomedical applications.