Ms. Hyekyung Lee

Ph.D. candidate

Seoul National University

Miss Hyekyung Lee received her BS from Pusan National University, and her master in Chemical Engineering from Seoul National University(SNU). She is currently a PhD candidate in Electrical Engineering, SNU. Her research interests include microfluidics, fluid dynamics and application of nonlinear electrokinetic transport. Her Ph.D. research focus on the fundamental of electrokinetics. She really eager to conduct research that can be applied to actual industries, not just at the laboratory level.

Overlimiting current in non-uniform arrays of microchannels

Overlimiting current (OLC) through electrolytes interfaced with perm-selective membranes has been extensively researched in recent years. Identified mechanisms responsible for OLC include surface conduction (SC), convection by electro-osmotic flow (EOF), and electro-osmotic instability (EOI). In each system, the dominant mechanism depends on input parameters such as surface charge and geometric constrictions. This work studies how a network of microchannels in a non-uniform array can induce OLC. To this end, micro/nanofluidic devices were fabricated with arrays of parallel microchannels with either uniform or non-uniform size distributions. All cases maintained the same fixed surface and bulk conduction. The current-voltage measurement demonstrated that OLC increased with increasing size non-uniformity up to a certain threshold. A visualization of internal flows indicates that parallel channels with non-uniform size induce flow loops across the network enhancing advective transport. These results can provide an understanding about ion transport in natural micro/nanoporous materials with random geometric structures.