Analytical modeling, simulations and experimental studies of a PZT actuated planar valveless PDMS micropump

This paper presents analytical modeling, 3-D electro-fluid-structural simulations, fabrication and test of a piezoelectrically actuated PDMS based planar valveless micropump. The analytical model considers force balance in the nozzle-diffuser elements and at the fluid-membrane interface to predict the natural frequency and flow rate performance of the proposed micropump. The numerical model employs two-way fluid-structure coupling to represent fluid-structure interaction (FSI) between the membrane and working fluid by mapping displacement data from the membrane to the fluid and force data from the fluid to the surface of the membrane. Also, electro-structure coupling between deformation of a piezoelectric disk due to an applied voltage and resulting displacement of the membrane is considered. Based on the simulations, the circular shape of the chamber used in conventional micropump designs is modified to include a taper at the outlet, which provides a significant improvement (∼28%) in the flow rate. Numerical simulations are performed to study the effects of the nozzle-diffuser angle and size, chamber diameter and height and membrane diameter and thickness on the flow rate. Using simulation results, a suitable design of the micropump is identified and the proposed micropump is fabricated. Experiments are performed to study the effect of frequency and voltage on the flow rate and pressure-flow characteristics. The predictions of the analytical model and numerical simulations in terms of flow rate versus frequency and voltage and pressure-flow characteristics compare well with the corresponding experimental data (within 20%). Using a peak-to-peak voltage of 30 V, the micropump delivers a maximum flow rate of 20 μL/min and back pressure of 220 Pa. The proposed micropump is polymer based and thus suitable for low-cost and disposable applications.