Enhanced separation of blood components

An apparatus for filtering blood, comprising:

• (a) a first surface of revolution,
• (b) a membrane comprising a second surface of revolution spaced from the first surface and defining therewith a gap of predetermined dimensions and geometry between the surfaces, the membrane containing through openings of nominal cross dimensions in excess of 0.9 microns,
• (c) inlet means for introducing blood into the gap,
• (d) means for rotating one of said surfaces about its axis of revolution relative to the other surface at an angular velocity such that shear stress, uniform over the membrane surface, is imposed on blood in the gap and laminar flow of the suspension in the gap is created whereby plasma is separated from the blood in the gap and passes through the membrane openings, and red cells in the blood are prevented from passing through the openings, and
• (e) first outlet means for collecting fluid passing through the membrane,
• (f) platelet rich plasma being passed through the holes of said membrane,
• (g) a second rotating membrane and a gap at one side thereof to which the platelet rich plasma is supplied,
• (h) the second membrane having holes therethrough of a size to pass plasma but to prevent passage of platelets,
• (i) whereby a platelet concentrate is produced in said gap.

The method of obtaining a platelet concentrate from raw blood, that includes

• (a) providing a first membrane with holes therethrough of a size to pass red blood cells, and supplying blood to one side of that membrane,
• (b) moving the membrane at sufficiently high velocity that shear conditions created in the blood adjacent the membrane cause particles in the blood to move or remain away from the surface of the membrane and from said holes,
• (c) creating a pressure differential across the membrane sufficient to cause plasma to pass through the holes from said one side of the membrane to the opposite side thereof, said plasma being platelet rich,
• (d) providing a second moving membrane and supplying the platelet rich plasma to one side of the second membrane,
• (e) the second membrane having holes therethrough of a size to pass plasma and to prevent passage of platelets,
• (f) whereby a platelet concentrate is produced at said one side of the second membrane.