Plasma separator-hydrostatic pressure type

Claim 2

A PISTON ADAPTED FOR USE FOR SEPARATING THE LIGHT PHASE OF BLOOD FROM THE CELLULAR OR HEAVY PHASE OF ANTI-COAGULANT TREATED BLOOD DISPOSED IN A SEPARATOR ASSEMBLY INCLUDING A BLOOD COLLECTION CONTAINER COMPRISING: A PISTON HAVING AN AVERAGE SPECIFIC GRAVITY HEAVIER THAN THE LIGHT PHASE OF BLOOD BUT LIGHTER THAN THE HEAVY PHASE SO THAT WHEN THE BLOOD IS SEPARATED INTO ITS COMPONENT PHASES THE PISTON WILL MIGRATE TO THE LIGHT PHASE-HEAVY PHASE INTERFACE SAID PISTON COMPRISING, A BODYPORTION WHICH IS GENERALLY CYLINDRICAL AND HAS A DIAMETER LESS THAN THE INTERNAL DIAMETER OF THE BLOOD COLLECTION CONTAINER A SUBSTANTIALLY NON-POROUS FLEXIBLE SLEEVE MEMBER MOUNTED AROUND SAID BODY PORTION AND SEALED AROUND THE TOP AND BOTTOM ENDS THEREOF THEREBY FORMING AN ANNULAR SPACE THEREBETWEEN SAID SPACE HAVING A GAS THEREIN SAID GAS HAVING A PRESSURE GREATER THAN ATMOSPHERIC PRESSURE AND SELECTED SO AS TO EXPAND THE FLEXIBLE BARRIER MEANS TO FORM A LIQUID-TIGHT SEAL WHEN MOUNTED WITHIN THE CONTAINER ANDD SAID GAS BEING COMPRESSIBLE WHEN SUBJECTING TO INCREASED HYDROSTATIC FORCE SO THAT THE FLEXIBLE BARRIER MEANS WILL MOVE AWAY FROM THE INNER WALLS OF THE CONTAINER TO BREAK THE SEAL AND PERMIT

Claim 3

The piston of claim 1 wherein the piston is formed of polystyrene having a specific gravity of substantially 1.06.

Claim 4

A blood separator assembly capable of separating anti-coagulant treated blood into its component parts of light phase and heavy phase comprising: a container having at least one open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase; 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; a piston having an average specific gravity lighter than the heavy phase but heavier than the light phase; said piston having a body portion which is generally cylindrical and has a diameter less than the internal diameter of the blood collection container; a compressible sleeve mounted on the interior walls of the container, so as to form a seal with said piston when said piston is positioned within said sleeve and said sleeve is uncompressed, the sleeve being made of closed cell elastomeric material having a smooth surface and said sleeve is responsive to hydrostatic forces whereby when said sleeve is compressed by subjugation to hydrostatic forces, said piston no longer forms a seal with said sleeve, thereby providing a passage for the light phase and heavy phase of the blood to move past the piston.

Claim 5

A blood separator assembly capable of separating anti-coagulant treated blood into its component parts of light phase and heavy phase comprising: a container having at least one open end which is adapted to receive blood for subsequent separation into a light phase and a heavy phase; 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; a piston having an average specific gravity lighter than the heavy phase but heavier than the light phase; said piston having a body portion which is generally cylindrical and has a diameter less than the internal diameter of the blood collection container; a compressible sleeve mounted on the interior walls of the container, so as to form a seal with said piston when said piston is positioned within said sleeve and said sleeve is uncompressed, the sleeve being made of closed cell elastomeric material having a smooth surface and said sleeve is responsive to hydrostatic forces whereby when said sleeve is compressed by subjugation to hydrostatic forces, said piston no longer forms a seal with said sleeve, thereby providing a passage for the light phase and heavy phase of the blood to move past the piston.

Claim 6

The assembly of claim 3 wherein the piston is formed of polystyrene having a specific gravity of substantially 1.06.

Claim 7

The assembly of claim 3 wherein said compressible sleeve is made of closed-cell elastomeric sponge material having a smooth surface.