Theoretical and experimental study of fluid behavior of a peristaltic micropump

Abstract

An embedded PZT actuated peristaltic micropump that is a part of an implantable medical drug delivery system was designed and fabricated using Microelectromechanical Systems (MEMS) technology. Three embedded PZT actuators drive the three micropump chambers in a peristaltic motion. Static deflection data of the micropump chamber actuated by the PZT was measured using Atomic Force Microscope (AFM). The deflection data are linear below 90 volts and initiate a slightly non-linear behavior above 90 volts to 130 volts that is the maximum voltage we drive our micropump. In order to obtain linear response between driving voltage and pumping performance, it is recommended to drive the embedded PZT to actuate the peristaltic micropump below 90 volts. Volumetric flow rate and maximum pumping pressure data of the peristaltic micropump for four different driving frequencies (0.5 Hz, 1 Hz, 2 Hz, and 4 Hz) at 90 volts were tested. Volumetric flow rate and maximum pumping pressure data of the peristaltic micropump for four different driving frequencies (0.5 Hz, 1 Hz, 2 Hz, and 4 Hz) at 130 volts were tested. The overall efficiency of the micropump for two driving voltages (90 volts and 130 volts) was calculated. For a volumetric flowrate of 6 /spl mu/L/min, the overall efficiency for the micropump driven at 90 volts was achieved at 0.015%. If our desired volumetric flowrate of the micropump is 10 /spl mu/L/min, the overall efficiency for the micropump driven at 90 volts will be even lower. This low overall efficiency tendency for the micropump is due to the more input power to increase the pumping performance. For the same volumetric flowrate of 6 /spl mu/L/min, the overall efficiency for the micropump driven at 130 volts was achieved at 0.060%, which is four times of the overall efficiency for the micropump driven at 90 volts. To improve the overall efficiency for the micropump that is for implanted) medical drug delivery systems, we recommend driving the micropump at a higher voltage than 90 volts. A theoretical model of the fluid behavior of the micropump was also developed with the assumption that the peristaltic micropump is working in a steady state flow. The fluid static behaviors (deflection, flowrate, and pumping pressure) from this model were compared with our experiment data. The experimental data meet with our theoretical model well.