A Disposable Magnetically Levitated Centrifugal Blood Pump for Extracorporeal Circulation Support

A disposable magnetically levitated centrifugal blood pump, which aims to be used for from a few days to a few months, has been developed. An impeller is levitated and rotated without contact using a two-degree-of-freedom radial magnetic bearing and a magnetic coupling. Due to ‘out-of-step’ of the magnetic coupling caused by its insufficient transmittable torque, a previous prototype pump could not yield the required pressure-flow characteristics of 5 L/min against 106 kPa (800 mmHg). The magnetic coupling was redesigned in order to increase the transmittable torque. The stability of the impeller levitation against impact was evaluated through a base excitation test simulating animal experiment and practical use. Applying an impulse excitation of an acceleration of 200 m/s2, the impeller could keep contactless levitation both in the controlled direction and in the passively supported directions. Finally, the animal experiments for one to two weeks showed that no damage and no thrombus formation were found in the pump heads.