Passive flow switching valves on a centrifugal microfluidic platform

In this paper we present two different methods for a passive flow switching valve on a centrifugal microfluidic platform, which controls the direction of a flowing liquid at a junction where a common inlet and two outlet channels meet. Switching of the flow can be performed either by relying on the Coriolis force that changes its pointing direction, perpendicular to the flow direction, with the rotational direction of a disk in a double layered arrangement at a symmetrical junction, or by means of the fluidic capacitance of an air pocket trapped between two fluids at a non-symmetric junction. This flow-switching valve, when combined with affinity-based separation techniques (e.g., adsorption of DNA on a silica matrix, followed by elution), has great potential in rapid bioassays and biomedical diagnostic applications that require the extraction of specific target biomoleclues. (C) 2007 Published by Elsevier B.V.