title: Electroosmotic capillary flow with nonuniform zeta potential
abstract: The present work is an analytical and experimental study of electroosmotic flow (EOF) in cylindrical capillaries with nonuniform wall surface charge (zeta-potential) distributions. In particular, this study investigates perturbations of electroosmotic flow in open capillaries that are due to induced pressure gradients resulting from axial variations in the wall zeta-potential. The experimental inquiry focuses on electroosmotic flow under a uniform applied field in capillaries with an EOF-suppressing polymer adsorbed onto various fractions of the total capillary length. This fractional EOF suppression was achieved by coupling capillaries with substantially different zeta-potentials. The resulting flow fields were imaged with a nonintrusive, caged-fluorescence imaging technique. Simple analytical models for the velocity field and rate of sample dispersion in capillaries with axial zeta-potential variations are presented. The resulting induced pressure gradients and the associated band-broadening effects are of particular importance to the performance of chemical and biochemical analysis systems such as capillary electrokinetic chromatography and capillary zone electrophoresis.
authors.affiliation: Stanford University, California 94305-4021, USA. aeh@leland.stanford.edu
authors.initials: AE
authors.lastname: Herr
authors.initials: JI
authors.lastname: Molho
authors.initials: JG
authors.lastname: Santiago
authors.initials: MG
authors.lastname: Mungal
authors.initials: TW
authors.lastname: Kenny
authors.initials: MG
authors.lastname: Garguilo