Sung Jae Kim

Abstract Ion concentration polarization (ICP) is a fundamental electrokinetic process that occurs near a perm-selective membrane under dc bias. Overall process highly depends on the current transportation mechanisms such as electro-convection, surface conduction and diffusioosmosis and the fundamental characteristics can be significantly altered by external parameters, once the permselectivity was fixed. In this work, a new ICP device with a bifurcated current path as for the enhancement of the

A perm-selective nanochannel could initiate concentration polarization near the nanochannel, significantly decreasing (increasing) the ion concentration in the anodic (cathodic) end of the nanochannel. Such strong concentration polarization can be induced even at moderate buffer concentrations because of local ion depletion (therefore thicker local Debye layer) near the nanochannel. In addition, fast fluid vortices were generated at the anodic side of the nanochannel due to the nonequilibrium el

Recently, a new type of electrokinetic concentration devices has been developed in a microfluidic chip format, which allows efficient trapping and concentration of biomolecules by utilizing ion concentration polarization near nanofluidic structures. These devices have drawn much attention not only due to their potential application in biomolecule sensing, but also due to the rich scientific content related to ion concentration polarization, the underlying physical phenomenon for the operation of

Ion concentration polarization is the fundamental transport phenomenon that occurs near ion-selective membranes, but this important membrane phenomenon has been poorly understood due to theoretical and experimental challenges. Here, we report the first direct measurements of detailed flow and electric potential profiles within and near the depletion region. This work is an important step toward a full characterization of this coupled transport problem. Using microfabricated electrodes integrated

We developed a reliable but simple integration method of polymeric nanostructure in a poly(dimethylsiloxane) (PDMS)-based microfluidic channel, for nanofluidic applications. The Nafion polymer junction was creased by infiltrating polymer solution between the gaps created by mechanical cutting, without any photolithography or etching processes. The PDMS can seal itself with the heterogeneous polymeric nanoporous material between the PDMS/PDMS gap due to its flexibility without any (covalent) bond

In this work, we investigated multiple vortical flows inside the ion concentration polarization (ICP) layer that forms due to a coupling of applied electric fields and the semipermeable nanoporous junction between microchannels. While only a primary vortex near perm-selective membrane is traditionally known to lead to electrokinetic instability, multiple vortexes induced by the primary vortex were found to play a major role in the electrokinetic instability. The existence of multiple vortexes wa

In this work, we experimentally investigated an effect of the hydrodynamic convective flow on ion transport through a nanoporous membrane in a micro/nanofluidic modeled system. The convective motion of ions in an ion concentration polarization (ICP) layer was controlled by external hydrodynamic inflows adjacent to the nanoporous membrane. The ion depletion region, which is regarded as a high electrical resistance, was spatially confined to a triangular shape with the additional hydrodynamic conv

Ion concentration polarization (ICP) has been extensively researched concerning new fundamentals in nanoscale electrokinetics and novel engineering applications. While biomedical and environmental ICP applications have a number of advantages compared to conventional methods, the technique has suffered from the critical limitation of low processing capacity because it has been usually presented in a micro/nanofluidic platform. In this paper, we devised micro fin structures inside a macroscale hig

Ionic current through a microchannel has drawn significant attention not only for fundamental electrokinetic research but also for the development of novel micro/nanofluidic applications. Among various ion transport mechanisms, surface conduction, which is a predominant mechanism in micro/nanofluidic devices, has been theoretically characterized based on two-dimensional analysis. However, its infinite axis assumption has become a barrier for direct application in practical micro/nanochannel netw

The ability of developing countries to cope with emerging standards in food and agricultural products is influenced by their institutional capacity. This paper develops original measures of four dimensions of standards-related, institutional capacity: information, conformity, enforcement, and international standard-setting. These measures are incorporated into a gravity model to investigate whether these capacities offset the negative effects of Aflatoxin B1 standards on food and agricultural pr

Solid-state nanopore is an ionic current-based biosensing platform, which would be a top candidate for next-generation DNA sequencing and a high-throughput drug-screening tool at single-molecular-scale resolution. There have been several approaches to enhance the sensitivity and reliability of biomolecule detection using the nanopores particularly in two aspects: signal-to-noise ratio (SNR) and translocation dwell time. In this study, an additional nano-well of 100-150 nm diameter and the aspect

Transition-metal-based layered triple hydroxides (LTHs) are evolving as potential positrode candidates for high-performance supercapacitors; however, their phase stabilization is still critical. Alongside, the availability of limited negatrodes pushes research toward exploring novel alternatives in order to minimize performance limitation issues in the fabricated supercapacitors. Herein, a facile strategy for stabilizing freestanding MnCuCo-LTH-based positrode possessing intermingled nanodisk-ne