Nafion-film-based micro-nanofluidic device for concurrent DNA preconcentration and separation in free solution

This paper presents a Nafion-film-based micro-nanofluidic device for concurrent DNA preconcentration and separation. The principle of the device is based on the combination of (a) ion concentration polarization phenomenon at the junction of the microchannel and the nanochannels in the Nafion film to form opposing electrophoretic and electroosmotic forces acting on the DNAs and (b) end-labeled-free solution electrophoresis to harness the charge-to-mass ratio for molecular differentiation. The experiments successfully demonstrated concurrent preconcentration and separation of DNA mixture in free solution within 240 s, yielding concentration ratios up to 1,150x and separation resolution of 1.85. The effect of applied electric field on the concentration and separation performance was also investigated. The device can be used as a key sample preparation element in conjunction with micro- or nano-fluidic sensors for microTAS functionality.