Magnetically levitated motor for rotary blood pumps.

The noncontact rotary pumps under development for use as artificial heart pumps are highly efficient and can prevent thrombus formation. In these pumps magnetic bearings have been widely used to support the rotors to avoid any physical contact. The use of magnetic bearings, however, has led to requirements for the control of a large degree of freedom and for a separate driving motor. This paper introduces 2 types of levitated motors, each of which uses a combination of a rotary motor and a magnetic bearing. These motors are suitable for use in artificial blood pumps because they are small in size and can replace contact components. The radial type levitated motor has the merit of being small in size and capable of controlling the 2 degrees of freedom in the x and y directions. The axial type motor controls only one degree of freedom in the z direction. This paper also introduces the theoretical background of the functions of the motor and magnetic bearing. Experimental results of tests of the proposed motor show a great potential for its application in rotary blood pumps.