BACKGROUND:In the blood flow through microvessels, platelets exhibit enhanced concentrations in the layer free of red blood cells (cell-free layer) adjacent to the vessel wall. The motion of platelets in the cell-free layer plays an essential role in their interaction with the vessel wall, and hence it affects their functions of hemostasis and thrombosis. OBJECTIVE:We aimed at estimating the diffusivity of platelet-sized particles in the transverse direction (the direction of vorticity) across the channel width in the cell-free layer, by in vitro experiments for the microchannel flow of red blood cell (RBC) suspensions containing platelet-sized particles. METHODS:Fluorescence microscope observation was performed to measure the transverse distribution of spherical particles immersed in RBC suspension flows through a Y-shaped bifurcating microchannel. We examined the development of the particle concentration profiles along the flow direction in the daughter channels, starting from asymmetric distributions with low concentrations on the inner side of the bifurcation at the inlet of the daughter channels. RESULTS:In the daughter channels of 40 μm width, the reconstruction of the particle margination to achieve a symmetric concentration profile was completed in ∼30 mm from the bifurcation, independent of flow rate. CONCLUSIONS:We presented experimental evidence of particle margination developing in the bifurcating flow channel, and the diffusivity of 2.9-μm diameter particles was estimated to be ∼40 μm2/s at the shear rate of 1000 s−1 and hematocrit of 0.2.

中文翻译：

---

悬浮在红细胞悬液中的血小板大小颗粒边缘流经 Y 形分叉微通道的发展

背景：在通过微血管的血流中，血小板在靠近血管壁的无红细胞层（无细胞层）中表现出更高的浓度。血小板在无细胞层中的运动在它们与血管壁的相互作用中起重要作用，因此它影响它们的止血和血栓形成功能。目的：我们旨在通过红细胞 (RBC) 悬浮液微通道流动的体外实验，估计血小板大小颗粒在无细胞层中通道宽度的横向（涡旋方向）扩散率含有血小板大小的颗粒。方法：进行荧光显微镜观察以测量浸没在 RBC 悬浮液中的球形颗粒的横向分布，流经 Y 形分叉微通道。我们检查了沿子通道流动方向的粒子浓度分布的发展，从子通道入口分叉内侧的低浓度不对称分布开始。结果：在 40 μm 宽度的子通道中，实现对称浓度分布的颗粒边缘重构在距分叉处约 30 mm 内完成，与流速无关。结论：我们提供了在分叉流道中形成颗粒边缘的实验证据，以及 2 的扩散率。