Tsugito Nakazeki

Recent Development of a Centrifugal Blood Pump with a Magnetically Suspended Impeller

To overcome the problem of shaft seal in conventional centrifugal pumps, a second prototype centrifugal blood pump with a magnetically suspended impeller has been developed, following the first prototype. The fluid dynamic design of this second prototype leads to elimination of the axial force and unbalanced radial force acting in the impeller. Consequently, three-component control systems are sufficient to position the impeller. Moreover, the impeller is suspended magnetically by the null-power system with a pair of permanent magnets and a controlled electromagnet. The impeller rotates via the magnetic coupling with permanent magnets embedded in the rotator of the motor. The performance of this pump is such that it can function as a blood pump. The fluid dynamic tests at present indicate that a combination of an impeller with radial blades and a diffuser with medially wide volute has the best pump performance.