Yamane T, Nishida M, Asztalos B, Tsutsui T, Jikuya T
Department of Material Science & Bioengineering, Mechanical Engineering Laboratory, MITI, Tsukuba, Japan.
ASAIO J. 1997 Sep-Oct;43(5):M635-8.
A monopivot magnetic suspension blood pump is a centrifugal pump under development with a magnetic suspension and a ceramic pivot to support the impeller with minimum contact. The pump size has been reduced by implementing a direct impeller drive mechanism in place of a magnetic coupling and motor. Flow visualization studies revealed that high shear, which seems to be closely related to hemolysis, concentrates in boundary layers near the walls. This implies that fluid dynamic shear can be reduced not by widening the gap, but by reducing the impeller velocity. Therefore, compared with the results of the previous semi-open curved vane impeller model, impeller velocity was reduced by 30% with a closed impeller having radial straight vanes, and smaller impeller/housing gaps. The volute shape around the impeller tip was also changed such that the outflow from the impeller enters along the center plane of the volute. To examine the effect of the improvements, hemolysis testing was conducted and found that the newly developed closed impeller model generated a lower level of hemolysis than the previous semi-open impeller model.
单枢轴磁悬浮血泵是一种正在研发的离心泵，采用磁悬浮和陶瓷枢轴以最小接触支撑叶轮。通过采用直接叶轮驱动机构取代磁耦合和电机，减小了泵的尺寸。流动可视化研究表明，似乎与溶血密切相关的高剪切力集中在壁面附近的边界层中。这意味着流体动力剪切力的降低不是通过扩大间隙，而是通过降低叶轮速度来实现。因此，与之前的半开式弯曲叶片叶轮模型的结果相比，采用径向直叶片的封闭式叶轮且叶轮/泵壳间隙更小时，叶轮速度降低了30%。叶轮尖端周围的蜗壳形状也进行了改变，使得叶轮流出的液体沿蜗壳的中心平面进入。为了检验改进效果，进行了溶血测试，结果发现新开发的封闭式叶轮模型产生的溶血水平低于之前的半开式叶轮模型。
