Preconcentration of lipid vesicles using concentration polarization in a microfluidic chip

This paper presents the first lipid vesicle preconcentrator using concentration polarization in a microfluidic chip. Concentration polarization is a well-known electrokinetic phenomenon, occurring near a micro/nanochannel interface. The preconcentrator is composed of a straight microchannel and a nanoporous membrane (Nafion strip) in it, which serves as a preconcentrating zone. We visualized the concentrated lipid vesicles near the Nafion strip and characterized the concentrating performance for different applied voltages. The maximum performance is the concentration ratio of 160 with 100 V in 10 min. This performance is at least comparable with the previous work and we believe that it has the advantages of lab-on-a-chip system compatibility and a relatively easy fabrication. Our concentration polarization platform on a PDMS chip is versatile so that the same device can be applied to other biomolecule preconcentration.