The motion of passive stability axes of levitated impeller at thin maglev ventricular assist device

We have developed a small, thin, maglev ventricular assist device (VAD), which can be implanted under the thorax muscle layer like a pacemaker. Radial position of a levitated impeller and its rotation are actively controlled by radial type self-bearing motor. An Axial position and tilt motion, stabilized passively with self-restoring characteristics of permanent magnets, are measured by using the three laser displacement sensors to evaluate the performance of the passive stability. Irregular motion of axial position and tilt angle of the levitated impeller caused by irregular hydrodynamic force are observed in higher flow rate condition and shut off condition. The impeller posture aligned in horizontally with increasing rotational speed due to the gyroscopic effect.