서강대학교

초록/요약

Here, we suggest a novel paper-based flow bifurcation system for preconcentration and field-flow separation based on hydrodynamic analysis. We present the results of a combined experimental and theoretical investigation of water imbibition through paper channels with wax boundaries to analyze the resistances of paper channels. Our model explains how hydrophobic channel boundaries affect the imbibition dynamics in the channels. To split a single flow stream stably, we design a straight paper channel connected with an expanded zone, which has a negligible hydrodynamic resistance compared with that of the straight channel, so we can make steady flow through the straight channel. By controlling the hydrodynamic resistances of channels, the fluid flow is bifurcated with the flow rate ratio up to 30 for 10 min. Such stable flow fractionation allows us to rebuild continuous-flow preconcentrator by ion concentration polarization (ICP) and field-flow separator. The continuous-flow preconcentrator successfully preconcentrates a fluorescent dye up to 33-fold. In addition, field-flow separator is demonstrated by dividing two different dyes depending on their surface charges. Our flow bifurcation systems expand the application of paper-based devices for point-of-care diagnostics, including preconcentration, and separation.