Abstract
We propose and successfully demonstrate a novel microfluidic mixer that takes advantage of field-effect control to dynamically manipulate local flow field to highly enhance mixing effect in microchannel. Theoretical analyses and numerical simulation have been done, including the influences of buffer pH, electrolyte concentration, and radial voltage on the ζ-potential, and the flow field analysis with nonuniform ζ-potential. Experimental results of fluid mixing for our electrokinetic micromixer have been characterized and indicate that over 90% mixing efficiency can be achieve for a 5 mm long microchannel. The velocity profile distortion resulting from nonuniform ζ-potential is also observed. The work reported here is considered as the first time temporal/spatial ζ-potential modulation for microfluidic mixer applications. © 2004 Elsevier B.V. All rights reserved.