This invention relates to an apparatus for separating platelets from blood samples by subjecting the blood sample to centrifugal force in the chamber while displacing the platelets from the blood sample by injecting a relatively small volume of saline into the centrifugally outer end of the chamber....http://www.google.ca/patents/US4268393?utm_source=gb-gplus-sharePatent US4268393 - Apparatus for centrifugal separation of platelet-rich plasma
