Patent ID: 6899692

Claim:
A filter device for being implanted in a blood vessel for carrying out in-vivo plasma separation comprising: one or more elongated hollow tubes and a plurality of elongated microporous fibers having an interior lumen extending along the length thereof, each fiber having a first and second end secured to one or more of said elongated hollow tubes, wherein the interior lumen of each of the fibers communicates with the interior of one or more of the hollow tubes, and wherein each of the elongated microporous fibers have an asymmetrical fiber wall morphology between the inner wall surface extending along the interior fiber lumen and the outer wall surface, said fiber wall having a higher mass density zone adjacent to the outer wall surface and a lower mass density zone adjacent to the inner wall surface, said higher mass density zone having a smaller average nominal pore size than the average nominal pore size in the lower mass density zone and wherein said fibers are capable of separating plasma from whole blood by passing plasma through said fiber wall from the outer wall surface to the inner wall surface and to said interior lumen thereof.