A centrifugal blood pump assembly according to one aspect of the invention includes a housing, an impeller adapted to rotate within the housing for feeding blood, an impeller position control device, and an impeller rotation torque generating device. The impeller rotates without contacting the inner...http://www.google.co.uk/patents/US5947703?utm_source=gb-gplus-sharePatent US5947703 - Centrifugal blood pump assembly
