Development of a Novel Axial Blood Pump With a Thrust Force Levitation Technology—Device Design and Levitation Experiments

The durability of a blood pump has been enhanced owing to the development of noncontact bearings. However, hydrodynamic bearings exhibit a risk of blood trauma owing to their narrow gaps, and magnetic bearings exhibit a risk of malfunctioning of their active control system. Therefore, in this study, we developed a blood pump that can levitate an impeller with a large gap without any active control system. In the proposed system, the impeller is levitated using a combination of the thrust force and permanent magnets. The thrust force, which is generated on the impeller as a reaction force to pump blood, changes based on the interaction between the housing geometry and impeller position. By utilizing this characteristic, the thrust force acted as a passive restoring force. A pump prototype was fabricated to verify the levitation. The experimental results showed that the impeller can be passively levitated in the axial direction by balancing the thrust and magnetic force with a gap of as low as 500 μm without active control. The pump head was 33.8 mmHg at 10 000 r/min and 1.5 L/min. The proposed principle is expected to contribute to the development of a blood pump with lower blood trauma and higher reliability.