Patent ID: 7828709

Claim:
A method separating fluid components comprising: rotating a separation chamber about a central rotation axis; flowing fluid components out of said separation chamber; regulating fluid flow in said separation chamber using at least one pump; passing light through said separation chamber; detecting an intensity of light from at least two regions in said separation chamber; comparing said intensities in said at least two regions; distinguishing incipient spill over changes in fluid flow in said separation chamber as a function of said intensities of transmitted light received from said at least two regions; regulating the speed of said at least one pump or the speed of said separation chamber in response to signals from a computational apparatus to avoid spill over of cellular components from said separation chamber; wherein said regions comprise a plasma region and a red blood cell region, said regions being placed such that, under normal circumstances, said plasma region observes primarily plasma and said red blood cell region observes primarily red blood cells; computing a first intensity ratio of intensity of said plasma region to intensity of said red blood cell region; and declaring a state of testing for possible spill over whenever said first intensity ratio exceeds a pre-determined value.