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Department of Electrical and Computer Engineering, Seoul National University, Seoul, Korea
21 July 2017
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In this presentation, an efficient sample preparation process utilizing an ion concentration polarization (ICP) phenomenon would be introduced, especially the simultaneous operation of separation and preconcentration and detailed dynamics of the preconcentrated analytes. ICP is traditional electrochemical ion transportation process and appears as a steep concentration gradient near nanoporous membrane under dc bias [1, 2, 3]. The major function of ICP is an active ion control by an external electric field so that it is significantly useful to study the new ion transportation through nanoporous junction (or membrane) and develop novel engineering applications [4, 5, 6].


Here, we would like to introduce a device as shown in Figure 1 performing selective preconcentration and online collection of charged molecules with different physicochemical properties based on ICP. The device allows subsequent processes of the highly preconcentrated and separated molecules on-chip or off-chip in a single solution. The molecules were highly preconcentrated at each equilibrium position balanced between electroosmotic drag force and electrophoretic force. By the repeated chamber geometry, the ion depletion zone was stabilized and the plugs were well-defined. For subsequent on-chip or off-chip application, pneumatic micro-valve system was integrated. The successive operation of selective preconcentration and valve operation would recover target molecules at the preconcentration factor more than 30 as shown in Figure 2.


Furthermore, we investigated the detailed spatiotemporal dynamics of preconcentrated analytes for multiple analyte mixture. In the case of single-analyte preconcentration, there were two distinct regimes: staking and propagating regime as shown in Figure 3. Meanwhile, the equilibrium position of the plug was shifted in the case of multiple analyte preconcentration due to electrokinetic intermolecular interactions. A critical mobility was extracted for determining the types of preconcentration and it was confirmed both by experiment and numerical simulations as shown in Figure 4.


These results would play a key role in enhancing accuracy of practical ICP applications through elucidating comprehensive preconcentration mechanisms which are critical in analytical systems such as diagnostics, biology researches, and point of care systems.


ion concentration polarization, nanoscale electrokinetics, selective preconcentration, dynamics

Cite this article as

Kim, S. DYNAMICS OF NANOELECTROKINETIC SELECTIVE PRECONCENTRATION . In Proceedings of the Optofluidics 2017, 25–28 July 2017; Singapore; doi:10.3390/optofluidics2017-04156

Author biographies

Sung Jae Kim
Professor Sung Jae Kim received the B.S. and M.S. degree in department of Chemical Engineering of Pohang University of Science and Technology, Pohang, Korea, in 1998 and 2000, respectively. He received his Ph.D. from department of Chemical Engineering and division of Mechanical and Industrial Engineering from the same university in 2005. He joined MIT as a postdoctoral associate in December 2005 and he continued to work as Research Scientist at the same group in MIT. From 2012, he joined Seoul National University as an assistant professor at Department of Electrical and Computer Engineering and promoted to an associate professor in 2016. His current research program focuses to the fundamental nanoscale electrokinetics especially ion concentration polarization phenomenon and its engineering application in the field of energy, environment and bio sector.