The method involves injecting a suspension (30) i.e. blood, on a circulation duct (10) with straight and curved sections (11, 12), and extracting a liquid enriched fraction (31) e.g. plasma enriched blood fraction, from the suspension. A suspension injected flow rate and a geometry of the duct are chosen, so that lift forces causes a concentration of blood cell enriched blood fraction (32) in a ring (42) around an longitudinal axis of the duct, in the section (11), and deanol secondary flows deform the ring and cause a spatial separation between the fractions (31, 32), in the section (12). An independent claim is also included for a microfluidic device for extracting a liquid phase from suspension comprising a circulation duct.
