The Influence of Working Fluid Viscosity on Pumping and Levitation Performance at Maglev Ventricular Assist Device

We have developed a small, thin, maglev ventricular assist device that can be implanted under the thorax muscle layer like a pacemaker. A radial type self-bearing motor and a cascade pump which has inlet and outlet ports in the same plane are integrated. The radial position of a levitated impeller and its rotation are actively controlled by the radial type self-bearing motor. Axial position and tilt motion are stabilized passively with characteristics of permanent magnets. In this paper, the pump characteristics and vibration due to the difference of two working fluid. The slope of the HQ characteristic and the damping ratio are affected by the viscosity of the working fluid．Oscillation amplitude of the levitated impeller in passive stabilized axes with 3 mPa･s working fluid decreases by 30 % compared with it in 1 mPa･s working fluid.