Measuring microchannel electroosmotic mobility and zeta potential by the current monitoring method

Abstract

Electroosmotic flow (EOF) is an electrokinetic flow control technique widely used in micro fluidic systems for applications including direct electrokinetic pumping, hydrodynamic pressure generation, and counter flow for micro fluidic separations. During EOF, an electric fi eld is applied along the length of a microchannel containing an electrolyte, with mobile ions near the charged microchannel walls experiencing a Coulomb force due to electrostatic interactions with the applied electric fi eld that leads to bulk solution movement. The goal of this laboratory is to experimentally determine the fi xed channel surface charge (zeta potential) and electroosmotic mobility associated with a given microchannel substrate material and buffer solution, using a simple current monitoring method to measure the average flow velocity within the microchannel. It is a straightforward experiment designed to help students understand EOF physics while gaining hands-on experience with basic world-To-chip interfacing. It is well suited to a 90-min laboratory session for up to 12 students with minimal infrastructure requirements. © Springer Science+Business Media, LLC 2013.