Patent ID: 8877142

Claim:
An assay device comprising a lid and a base, said base comprising a sample addition zone, a reaction zone and an absorbing zone, each of said zones being in fluid connection and component parts of a defined fluid passage leading from the sample addition zone to the absorbing zone, said device further comprising: a) a sample addition well integrated in the lid; b) the absorbing zone comprising an area on an non-porous substrate defining said base, said absorbing zone having projections that are perpendicular relative to said substrate, the area of said absorbing zone being directly covered by a foil in which said foil, said projections and said substrate define a volume which together with the volume of the fluid passage further define a sample volume subjected to the assay device and in which said foil or an adhesive attaching said foil to said projections of said absorbing zone has hydrophilic properties that increase the flow velocity of fluid along said fluid passage; c) each of the zones of said defined fluid passage comprising projections perpendicular relative to said base, said projections commonly having a height, diameter and center to center distance between the projections such that lateral capillary flow of said fluid from said sample addition zone toward said absorbing zone along said defined fluid passage is achieved by said projections; and d) at least one filter disposed between the sample addition well and the sample addition zone, wherein said at least one filter is a hydrophilic polymeric membrane capable of separating red blood cells from plasma, and wherein said at least one filter is in contact with the perpendicular projections in the sample addition zone and in which the flow rate of fluid through said assay device along said defined fluid passage is controlled by selection of the hydrophilic properties of said foil or said adhesive attaching said foil to said projections of said absorbing zone and in which the foil solely covers the absorbing zone of the assay device.