Homopolar Magnetic Levitation Motor for Total Artificial Heart

In this paper, we report a prototype of a total artificial heart with a homopolar type of magnetic levitation motor.This motor's outer diameter and height are 50 mm.A rotor with an outer diameter of 14 mm is placed inside a stator with an inner diameter of 18 mm, and the radial position and radial tilt are actively controlled through a clearance of 2 mm.The axial position is passively supported by the magnetic system's stability.We introduce a mechanism that adjusts left-right blood flow balance by MR fluid transmission, utilizing axial displacement due to the left-right atrial pressure difference.By preload response test, a displacement performance is 0.07 mm with a 5-mmHg pressure difference.To reach a target axial displacement of 0.5 mm, we conducted 3D magnetic field analysis and propose a method for reducing the magnetic system's restoring force when the impeller is axially displaced.