A novel approach to analysis of electroosmotic pumping through rectangular-shaped microchannels

Abstract

In this paper, a simple but accurate modeling method for obtaining analytical solutions for the fundamental characteristics of electroosmotic flow through rectangular pumping channels without the Debye–Hückel approximation is presented. The Poisson–Boltzmann equation without the Debye–Hückel approximation for the electric potential distribution and the momentum equation for the velocity profile are averaged and solved analytically. To validate the modeling method proposed in the present work, electroosmotic flows through a rectangular capillary whose side is 50 μm are experimentally investigated. The zeta potential at the silica–potassium phosphate buffered saline interface is measured by the streaming potential technique. The pressure driven flow characteristics of and the maximum electroosmotic flow rate through the capillary are measured. By comparing these experimental data and numerical solutions for original governing equations with the analytical solutions, the present analytical method is validated. It is found that the present modeling method is applicable when the ratio of a half of the channel width to the electric double layer thickness is larger than 3. From a parametric study for various configurations of the pumping channel based on the analytical solutions, it is shown that the pumping power can be increased by one order of magnitude with decreasing channel width.