Sample concentration in a microfluidic paper-based analytical device using ion concentration polarization

We report a low-cost approach for sample concentration in a microfluidic paper-based analytical device using ion concentration polarization. This device platform can attain liquid sample filling by capillary suction through the microporous paper and ion selective transport through a nanoporous polymer matrix under DC electric field. The device demonstrated a fast depletion of fluorescent dye samples and can serve as an effective microfluidic concentrator of fluorescent dye with 60-fold concentration enhancement achieved within 200 s. The device fabrication is simply based on paper cutting and lamination without the need of lithography and printing of hydrophobic material such as wax. The lamination approach presented in this paper has the potential to be transferred to a large-scale production of paper-based analytical devices.