The hollow fiber membrane bundle is the functional component of artificial lungs, transferring oxygen to and carbon dioxide from the blood. It is also the primary location of blood clot formation and propagation in these devices. The geometric design of fiber bundles is defined by a narrow set of parameters that determine gas exchange efficiency and blood flow resistance, principally: fiber packing density, path length, and frontal area. These same parameters also affect thrombosis. This study investigated the effect of these parameters on clot formation using 3D printed flow chambers that mimic the geometry and blood flow patterns of fiber bundles. Hollow fibers were represented by an array of vertical micro‐rods (380 μm diameter) arranged with three packing densities (40%, 50%, and 60%) and two path lengths (2 and 4 cm). Blood was pumped through these devices corresponding to three mean blood flow velocities (16, 20, and 25 cm/min). Results showed that (1) clot formation decreases dramatically with decreasing packing density and increasing blood flow velocity, (2) clot formation at the outlet of the fiber bundle enhances deposition upstream, and consequently (3) greater path length provides greater clot‐free fiber surface area for gas exchange than a shorter path length. These results can help guide the design of less thrombogenic, more efficient artificial lung designs.

中文翻译：

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人工肺纤维束几何设计对微观和宏观尺度凝块形成的影响


中空纤维膜束是人工肺的功能部件，将氧气输送到血液中，并从血液中输送二氧化碳。它也是这些设备中血凝块形成和传播的主要位置。纤维束的几何设计由一组狭窄的参数定义，这些参数决定了气体交换效率和血流阻力，主要是：纤维堆积密度、光程长度和正面面积。这些相同的参数也会影响血栓形成。本研究使用模拟纤维束几何形状和血流模式的 3D 打印流动室调查了这些参数对凝块形成的影响。中空纤维由一系列垂直微棒（直径 380 μm）表示，这些微棒具有三种填充密度（40%、50% 和 60%）和两种光程（2 和 4 cm）。血液通过这些设备泵送，对应于三个平均血流速度（16、20 和 25 cm/min）。结果表明，（1） 凝块形成随着堆积密度的降低和血流速度的增加而急剧减少，（2） 纤维束出口处的凝块形成增强了上游的沉积，因此 （3） 与较短的路径长度相比，较大的光程长度为气体交换提供了更大的无凝块纤维表面积。这些结果可以帮助指导设计血栓形成率更低、效率更高的人工肺设计。