The purpose of this study is to establish an optimal design of the multi-arc hydrodynamic bearing in a centrifugal blood pump for improvement of bearing stiffness and hemolysis level. The multi-arc bearing was designed to fulfill the required specification: (i) ensuring the uniform bearing stiffness against various bearing angles, (ii) ensuring the higher bearing stiffness than the centrifugal force to prevent the impeller whirl, and (iii) adjusting bearing clearance as much as possible to reduce hemolysis. First, we performed the numerical analysis to optimize three design parameters of the multi-arc bearing: number of arc N, bearing clearance C and groove depth H. To validate the accuracy of the numerical analysis, we measured the impeller trajectories. Finally, in vitro hemolysis test was conducted to evaluate the hemolysis level of the multi-arc bearing. As a result of the numerical analysis, the optimal parameter combination of the multi-arc bearing was determined as follows: N of 4, C of 100 μm and H of 100 μm. In the measurements of the impeller trajectory, the optimal parameter combination was found out to be as follows: N of 4, C of 90 μm and H of 100 μm. This result showed high reliability of the numerical analysis. In the hemolysis test, the relative hemolysis level of the multi-arc bearing was 0.8-times higher than that of the cylindrical bearing. It was found that the multi-arc bearing can reduce the hemolysis level. In conclusion, we could optimize the multi-arc bearing for improvement of bearing stiffness and hemolysis level.
