Patent ID: 7223346

Claim:
A blood platelet collection device comprising a centrifugal spin-separator container having a cavity with a longitudinal inner surface, the spin-separator container enclosing a flexible inner tube; the flexible inner tube having an inner surface; a float positioned within the flexible inner tube; the float having an outer surface in sealing engagement with the inner surface of the flexible tube in a neutral pressure condition, the sealing engagement preventing movement of fluid between the outer surface of the float and the inner surface of the flexible tube in a neutral pressure condition; the outer surface of the float disengaging from contact with the inner surface of the flexible tube in an elevated pressure condition, thus enabling movement of fluid between the outer surface of the float and the inner surface of the flexible tube in the elevated pressure condition and movement of the float within the flexible inner tube; the float having a density less than the density of erythrocytes and greater than the density of plasma; the float having a platelet receptor cavity with a platelet collection surface positioned immediately below the level of the platelet layer in separated blood after centrifugation; and the float having a channel communicating with the platelet receptor cavity for removing separated platelets after centrifugation.