Experimental investigation of electrokinetically generated in-plane vorticity in a microchannel

Electrokinetic generation of micro-flow patterns has advanced in recent years and received significant attention due to promising applications in biotechnology. Basic flow fields like bi-directional shear and out-of-plane vortices have been generated electrokinetically in microchannel liquid flow using various surface-charge patterns. In-plane vortex flows present a higher challenge since positive and negative charge regions on the same surface are required. Utilizing a newly-developed polymer-coating technology, the fabrication and characterization of microchannel devices with a variety of charge patterns are reported. Pairs of in-plane counter-rotating vortices or serpentine-like vortical motion have been observed depending on the absence or presence of a mean flow. The experimental results have been found to be consistent with CFD computations using a commercial code.