title: Separation mechanisms underlying vector chromatography in microlithographic arrays.
abstract: Micropatterned chips possessing an asymmetric, spatially periodic array of obstacles enable the vector (directional) chromatographic separation of charged particles animated by an external electric field. We apply a network theory to analyze the chip-scale (L-scale) transport of finite-size Brownian particles in such devices and identify those factors that break the symmetry of the chip-scale particle mobility tensor, most importantly the hydrodynamic wall effects between the particles and the obstacle surfaces. Our analysis contrasts with prevailing separation theories, which are limited to effectively point-size particles, for which wall effects are negligible. These theories require a biasing of obstacle-scale (l-scale; l<<L) bifurcation branches within the network. Such bifurcations are shown to constitute but one factor in modeling the vector chromatography of finite-size particles, and not necessarily the dominant factor.
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Dorfman
authors.forename: Howard
authors.initials: H
authors.lastname: Brenner