- Thrust–Magnetic Hybrid Levitation Ventricular Assist Device -
Overview
The artificial heart is an implantable medical device that circulates blood by rotating an impeller, and is used in the treatment of patients with severe heart failure. In the latest artificial heart models, the impeller is levitated using magnetic bearings or hydrodynamic bearings, achieving both hemocompatibility and high durability.
This impeller levitation technology has enabled long-term home treatment (Destination Therapy) for patients with implanted artificial hearts. In this research, we aim to develop an artificial heart equipped with a thrust–magnetic hybrid levitation mechanism that combines the advantages of magnetic bearings (large-gap levitation) and hydrodynamic bearings (passive levitation without active control).
A New Passive Levitation Method Combining Two Forces
According to Earnshaw’s theorem, it is impossible to stably levitate an object in all degrees of freedom using only the static magnetic fields of permanent magnets.
Levitation can be achieved by actively controlling displacement feedback with electromagnets, but this requires sensors and computation systems.
In this study, we propose a new passive levitation method in which the impeller spontaneously levitates during rotation by combining thrust and magnetic forces, without the need for feedback control.
When the impeller rotates, it pushes blood forward, and the reaction force from the blood acts as thrust—similar to how propulsion works in ships. We apply this principle to the artificial heart, enabling the impeller to levitate as if it were “swimming” inside the pump.
Challenge Toward Fully Passive Levitation
To stably levitate a rotating body by combining thrust and magnetic forces, it is essential to balance the two forces appropriately.
In this research, we are developing design methods to improve performance by combining computational fluid dynamics (CFD) analysis and magnetic field analysis with experimental design techniques and 3D printing.
No previous study has ever achieved impeller levitation using this approach. Our goal is to realize the world’s first artificial heart equipped with this novel levitation method.
