Serum/plasma separator assembly with interface-seeking piston having coarse and fine band filters

Claim 1

A SEPARATOR ASSEMBLY CAPABLE OF SEPARATING BLOOD INTO A PLASMA/SERUM OR LIGHT PHASE AND A CELLULAR OR HEAVY PHASE COMPRISING: A CONTAINER HAVING AT 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, AN INTERFACE-SEEKING PISTON HAVING A SPECIFIC GRAVITY GREATER THAN BLOOD AND SLIDABLY MOUNTED IN THE CONTAINER AND HAVING MEANS ON AN OUTER SURFACE FOR PROVIDING SEALING ENGAGEMENT WITH AN INNER SURFACE OF THE CONTAINER, SAID MEANS INCLUDING AT LEAST TWO RADIALLY EXTENDING DEFORMABLE SEAL RINGS MOUNTED ON THE PISTON AND DISPOSED AT THE LOWER AND UPPER ENDS THEREOF AND A NOTCHED RADIALLY EXTENDING RING DISPOSED BETWEEN SAID UPPER AND LOWER SEAL RINGS, SAID SEAL RING BEING CAPABLE OF BEING DEFORMED TO OPEN A PATH AROUND SAID PISTON WHEN SAID ASSEMBLY IS SUBJECTED TO CENTRIFUGAL FORCE, A FILTER ASSEMBLY MOUNTED ON SAID PISTON AND POSITIONED BETWEEN SAID UPPER AND LOWER SEAL RINGS AND BEING IN SLIDABLY SEALING ENGAGEMENT WITH THE INNER SURFACE OF THE CONTAINER SO THAT SEPARATED PLASMA/SERUM IS FILTERED WHEN SAID ASSEMBLY IS CENTRIFUGED, SAID FILTER ASSEMBLY INCLUDING A FIRST FILTER ELEMENT LOCATED ADDJACENT TO SAID UPPER SEAL RING AND HAVING AN AVERAGE PORE SIZE SMALLER THAN SAID HEAVY PHASE AND A SECOND FILTER ELEMENT LOCATED ADJACENT TO AID LOWER SEAL RING AND HAVING AN AVERAGE PORE SIZE GREATER THAN SAID HEAVY PHASE AND SAID FILTER ASSEMBLY PROVIDING PISTON STOP MEANS WHEN SAID PISTON IS AT THE PLASMA/SERUM-CELLULAR INTERFACE WHEREBY THE CELLULAR PHASE CLOG SAID FIRST FILTER ELEMENT PREVENT THE UPWARD FLOW OF PLASMA/SERUM THERETHROUGH SO THAT THE PISTON AUTOMATICALLY STOPS AT SAID INTERFACE.