An electrokinetic device for selective preconcentration and online collection based on ion concentration polarization

This paper reports a micro/nanofluidic device performing selective preconcentration and collection of two different charged molecules with different physicochemical properties using ion concentration polarization (ICP). By the balance between electroosmotic drag force and electrophoretic force on the molecules, two different dyes were highly preconcentrated and separated simultaneously. With the repeated geometry, ion depletion zone was stabilized and the selectively preconcentrated plug was well-defined. For subsequent on-chip or off-chip applications, pneumatic microvalve system was integrated and helped to collect the selectively preconcentrated plug into another location in a single solution. Alexa Fluor 488 was collected more than 30-fold within 30 minutes from the original sample mixture of Sulforhodamine B and Alexa Fluor 488 without further diffusion or dispersions. This integrated device provided the potential of selective preconcentration system to be used for online analytical system such as point-of-care applications.