title: Experimental optimization of flow distributors for pressure-driven separations and reactions in flat-rectangular microchannels.
abstract: We report on the results of an experimental study established to optimize the design of microfabricated flow distributors for use in pressure-driven separations and reactions in flat-rectangular channels. For this purpose, the performance of a wide variety of possible flow distributor designs etched in glass/silicon wafers was compared, using CCD camera detection to study the shape and variance of the bands eluting from them. The best performance was obtained with radially interconnected distributors with a diverging inlet section and filled with diamond-shaped pillars, oriented perpendicular to the main flow direction and with a high transversal over axial aspect ratio. It was found that the best distributor designs start with a diverging section containing some 10-12 subsequent rows of high aspect ratio pillars (with a transversal width making up 10-15% of the final channel width) and with a divergence angle selected such that the sloped side-walls run parallel with the sides of the diamond-shaped pillars. After this zone, one or more regions with pillars with a smaller aspect ratio should be provided to increase the number of exit points. To prevent the formation of dead zones in these subsequent zones, so-called distributor wedges can be used to prevent the formation of any dead zones in the wake of the large aspect ratio pillars of the preceding section.
authors.affiliation: Department of Chemical Engineering (Transport Modelling & Analytical Separation Science-group), Vrije Universiteit Brussel, Brussels, Belgium.
authors.forename: Joris
authors.initials: J
authors.lastname: Vangelooven
authors.forename: Stefan
authors.initials: S
authors.lastname: Schlautman
authors.forename: Frederik
authors.initials: F
authors.lastname: Detobel
authors.forename: Han
authors.initials: H
authors.lastname: Gardeniers
authors.forename: Gert
authors.initials: G
authors.lastname: Desmet