Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump
Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump
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DOI：
10.1243/09544119jeim352
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发表时间：
2008-05-01
期刊：
影响因子：
1.8
通讯作者：
Kameneva, M. V.
中科院分区：
文献类型：
--
作者：
Antaki, J. F.;Diao, C-G;Kameneva, M. V.
主要流道与辅助流道空间尺度的巨大差异是涡轮动力血泵定量化设计面临的一个长期挑战。叶尖内和叶尖附近的流体通道通常是几个血细胞的尺度，混淆了宏观连续体模型的应用。然而，正是在这些区域存在最大的剪切应力，这是最容易造成细胞损伤。这种差异促使这些微观研究可视化血细胞在微型涡轮动力血泵的小间隙内的运动学。制备了一个透明的微型离心泵模型，该模型具有可调的叶顶间隙（50-200 μ m），用于直接光学可视化叶轮叶顶与固定壳体之间的区域。通过显微镜可视化系统获得血细胞的同步图像，该系统由装有长工作距离物镜（40倍）的倒置显微镜、水银灯和由叶轮旋转电子触发的高分辨率电荷耦合器件相机组成。7 μ m荧光粒子实验揭示了间隙尺寸对叶片厚度轨迹的影响。与200 μ m间隙相比，50 μ m间隙中速度的横向分量（垂直于叶片）显著增强，从而缩短了暴露时间。用稀释的牛血液（Ht = 0.5%）进行的研究表明，当叶尖间隙从200 μ m减小到50 μ m时，穿过间隙的细胞浓度也显著降低（30%）。这些结果激发了对涡轮动力血泵内细胞损伤的微流体现象的进一步研究。
A persistent challenge facing the quantitative design of turbodynamic blood pumps is the great disparity of spatial scales between the primary and auxiliary flow paths. Fluid passages within journals and adjacent to the blade tips are often on the scale of several blood cells, confounding the application of macroscopic continuum models. Yet, precisely in these regions there exists the highest shear stress, which is most likely to cause cellular trauma. This disparity has motivated these microscopic studies to visualize the kinematics of the blood cells within the small clearances of a miniature turbodynamic blood pump.A transparent model of a miniature centrifugal pump having an adjustable tip clearance (50-200 mu m) was prepared for direct optical visualization of the region between the impeller blade tip and the stationary housing. Synchronized images of the blood cells were obtained by a microscopic visualization system, consisting of an inverted microscope fitted with long-working-distance objective lens (40x), mercury lamp, and high-resolution charge-coupled device camera electronically triggered by the rotation of the impeller.Experiments with 7 mu m fluorescent particles revealed the influence of the gap dimension on the trajectory across the blade thickness. The lateral component of velocity (perpendicular to the blade) was dramatically enhanced in the 50 mu m gap compared with the 200 mu m gap, thereby reducing the exposure time. Studies with diluted bovine blood (Ht = 0.5 per cent) showed that the concentration of cells traversing the gap is also reduced dramatically (30 per cent) as the blade tip clearance is reduced from 200 mu m to 50 pm. These results motivate further investigation into the microfluidic phenomena responsible for cellular trauma within turbodynamic blood pumps.