A Planar Electroosmotic Micropump for Lab-on-Microchip Applications

Abstract

AbstractThe scope of the paper is to provide a theoretical and experimental treatment allowing to optimize critical design parameters for planar electroosmotic micropumps. The suggested design with a vertical arrangement of multiple narrow polymer pumping microchannels reduces the pump area to 1/10 compared to planar micropumps with widened shallow pumping channels. This design allows the fabrication of the channel system in only one process step, compatible with post-CMOS processing and suitable for monolithical integration on labchips. A simple analytical model has been developed to characterize the flow rate in a field free pressure-driven section of the channel. It is shown that the micropump with optimized dimensions of rib structures makes possible high pressure low voltage pumping. For high pressure capacity the distance between the ribs must be on the order of 0.5-1 µm with an aspect ratio of 10-20. The electroosmotic micropump with microchannels of SU-8 and polyacrylamide gel electrodes has been fabricated and tested. The pumping rate is bidirectionally linear and reached 10 nl/min at applied voltage of 40 V in 1 cm long pressure-driven channel, which corresponds to zero-flow pressure of 65 Pa.