Patent ID: 8506823

Claim:
A method of separating a biological fluid having multiple components, said method comprising: centrifuging an enclosure having an interior circumferential surface defining a chamber containing a biological fluid having multiple components and a float slideably disposed within the enclosure, the float partitioning the enclosure into a lower volume zone and an upper volume zone and wherein the float comprises an interior isolation chamber defining an intermediate volume zone and an exterior circumferential surface circumferentially spaced from the interior circumferential surface of the enclosure for defining a circumferential gap therebetween; utilizing a first valve means for opening and closing communication of biological fluid from the upper volume zone to the intermediate volume zone defined by the interior isolation chamber within the float; and utilizing a second valve means for opening and closing communication of biological fluid from the intermediate volume zone defined by the interior isolation chamber within the float to the lower volume zone of the enclosure wherein under centrifugation the first valve means and the second valve means control at least one closed loop circulation of biological fluid into the interior isolation chamber from the upper volume zone, out of the interior isolation chamber into the lower volume zone, out of the lower volume zone and through the circumferential gap to the upper volume zone, and back into the interior isolation chamber as a function of a first pressure differential of biological fluid on the first valve means and as a function of a second pressure differential of biological fluid on the second valve means for isolating at least a portion of at least one target component of the multiple components of the biological fluid within the interior isolation chamber of the float during the centrifuging step.