Selective preconcentration and online collection of charged molecules using ion concentration polarization

Abstract

A multilayer micro/nanofluidic device was presented for the selective preconcentration and online collection of charged molecules with different physicochemical properties based on ion concentration polarization phenomena. With a balance of electroosmotic drag force and electrophoretic force on the molecules, a sample mixture of sulforhodamine B and Alexa Fluor 488 could be highly preconcentrated and separated simultaneously. A repeated microchamber structure was employed to capture each dye at a desirable position. For subsequent on-chip or off-chip application, pneumatic microvalves were integrated and selectively collected the target dyes with cyclic valve operations. Using the integrated system, Alexa Fluor 488 was solely collected (with a separation resolution of 1.75) out of the mixture at a 30-fold preconcentration ratio. This integrated device would be a key component for lab on a chip applications.