(411j) Partition-Induced Vector Chromatography (PIVC) in Microfluidic Devices: Experiments and Simulations

We study the separation of suspended colloidal particles moving in a slit channel in which the bottom wall presents either parallel gold stripes or nanometer deep trenches. We show that differences in the equilibrium partition coefficient of the suspended particles lead to vector chromatography, in that particles with different partition ratios migrate at different angles when driven by either an external force or a flow field that is at an oblique angle with respect to the stripes. We demonstrate the potential of PIVC by means of macrotransport theory, in the Fick-Jacobs limit, and Brownian Dynamics simulations for a broad range of Peclet numbers. We validate these ideas with experiments separating polystyrene and silica particles of the same and different size in a microfluidic device. PIVC has the potential to become a technique as versatile as field-flow fractionation due to the vast range of physicochemical properties that can be employed to induce partition.