Apparatus and method for separating cells from biological fluids

Abstract

A centrifugal rotor for separating plasma from whole blood includes a plurality of internal chambers and passages for combining the plasma with one or more reagents and distributing the plasma to a plurality of individual test wells. The chambers and passages necessary for separating the whole blood into plasma are located on a first, upper level within the rotor and include a measuring chamber, an overflow chamber, a separation chamber, and a reagent chamber. The measuring chamber and overflow chamber have capillary dimensions so that an initial volume of whole blood partitions therebetween, with the measuring chamber filling first to provide a preselected volume. The separation chamber is located radially outward from both the measuring chamber and the reagent chamber to that spinning of the rotor causes both the reagent and the measured blood volume to flow outward into the separation chamber. The separation chamber includes a radially-outward cell trap and a radially-inward drainage port so that spinning of the rotor causes the cellular components of the whole blood to enter the cell trap, while cessation of spinning allows the separated plasma to flow downward through the drainage port. A collection chamber is formed at a lower level than the rotor to receive the plasma through the drainage port. Further spinning of the rotor causes the plasma to flow radially outward into a plurality of test wells formed around the periphery of the collection chamber. Testing of the separated plasma volumes may be performed without removing the plasma from the rotor.