Serum/plasma separators with centrifugal valves

Claim 1

A self-contained fluid separator assembly, capable of separating blood into its component parts of plasma or serum and cellular portion, comprising: a. a container having at least one open end which is adapted to receive blood for subsequent separation into a light phase ans a heavy phase; b. a closure sealing the open end of the container, the closure being formed of a self-sealing elastomeric material which is penetrable by a cannula through which blood to be separated is conducted into the container; c. a piston having a specific gravity relatively greater than the cellular portion of the blood and slidably mounted in the upper portion of the container and having means on an outer surface in sealing engagement with an inner surface of the container; d. centrifugally actuated valve means associated with said piston, said valve means being in the form of a downwardly projecting substantially dome-shaped concave diaphragm having a specific gravity greater than blood and having a slit therein openable when subjected to substantial centrifugal force, said valve means being normally closed, so that when said container is subjected to moderate centrifugal force the blood separates into its light phase and heavy phase with the piston staying in the upper portion of the container, and subsequently when increased centrifugal force is used on the valve means automatically opens with the light phase passing up through the valve means enabling the piston to move down through the light phase while retaining sealing engagement with the inner surfaces of the container, said valve means remaining open until termination of the substantial centrifugal force; and mechanical stop means on the container whereby the piston when moving through the light phase will stop a predetermined distance from one of the ends of the container followed by termination of substantial centrifugal force which permits the vlave means to automatically shift from an open position to a closed position to provide an impervious barrier between the separated light phase and heavy phase of the blood.