Characterisation of microparticle transport driven by ionic current conditions in electrically polarised aqueous solutions

Abstract

Molecular transport technology is one of the hottest topics in micro- and nanofluidics. Target molecules are often transported by electric forces, e.g. capillary electrophoresis (EP), gel EP, biological and artificial nanopores. On the other hand, such methods are sometimes disturbed by surrounding environments because the surface effects tend to be prominent. The surface charges on the channel walls cause peculiar liquid flows in micro- and nanochannels. Thus, the isolation of electrophoretic transport from the fluidic effects is important to achieve the precise control of targets in confined spaces. In this study, a novel technique to control the transport of microparticles is proposed, where a liquid flow is involved by applying electric body forces. The direction of electrically charged microparticles is controlled by the electric forces not only on the particle but also in the liquid. Herein, an electrohydrodynamic flow is applied by preparing electrically polarised solutions. In this setup, the transport direction of particles can be changed depending on the electric forces by excessive ions, which is estimated by measuring electric conductivity.