OPTIMAL DESIGN FOR THE MAGNETIC SUSPENDED CENTRIFUGAL BLOOD PUMP

Abstract

An optimal design method for the maglev system is devised to develop a miniature and high performance maglev pump. There are trade-off problems on the maglev artificial heart design. For example, the device should be small enough for implantation. But, the small device has limited performance for force generation to suspend an impeller with the magnetic circuit. For another example, the gap between the levitated impeller and a pump casing is a main factor to determine the efficiency of the magnetic system. Narrow gap is suitable for the efficiency, but is not good for hemolysis property. For optimal design, a theoretical design model for a maglev centrifugal blood pump with a self-bearing motor is constructed based on the magnetic circuit theory. The self-bearing motor consists of the magnetic stator at the center of the pump, outer rotor ring with an impeller at the circumferential space of the stator. Relationships among model parameters are defined as restriction conditions. The thickness of magnets, the diameter of the stator and the turn number of electromagnet coils are optimized to achieve the small size and high efficient performance with pre-determined stiffness. As a result, the diameter of the stator could be reduced from 60 mm to 55 mm with no deterioration of the generated force. Also, the energy consumption was reduced from 16 W to 11 W against a head of 100 mm Hg with a flow rate of 5 L/min. Developed design method is useful to optimize the maglev pump and the optimized pump indicated sufficient performance as a ventricular assist device.