Department of Biomedical Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
Department of Mechanical and Aerospace Engineering, Rutgers, The State University of New Jersey, Piscataway, NJ, USA.
Artif Organs. 2021 Sep;45(9):1083-1096. doi: 10.1111/aor.13941. Epub 2021 Apr 8.
There is a long history of research examining red blood cell (RBC) partitioning in microvasculature bifurcations. These studies commonly report results describing partitioning that exists as either regular partitioning, which occurs when the RBC flux ratio is greater than the bulk fluid flowrate ratio, or reverse partitioning when the RBC flux ratio is less than or equal to that of the bulk fluid flowrate. This paper presents a study of RBC partitioning in a single bifurcating microchannel with dimensions of 6 to 16 μm, investigating the effects of hematocrit, channel width, daughter channel flowrate ratio, and bifurcation angle. The erythrocyte flux ratio, N*, manifests itself as either regular or reverse partitioning, and time-dependent partitioning is much more dynamic, occurring as both regular and reverse partitioning. We report a significant reduction in the well-known sigmoidal variation of the erythrocyte flux ratio (N*) versus the volumetric flowrate ratio (Q*), partitioning behavior with increasing hematocrit in microchannels when the channel dimensions are comparable with cell size. RBCs "lingering" or jamming at the bifurcation were also observed and quantified in vitro. Results from trajectory analyses suggest that the RBC position in the feeder channel strongly affects both partitioning and lingering frequency of RBCs, with both being significantly reduced when RBCs flow on streamlines near the edge of the channel as opposed to the center of the channel. Furthermore, our experiments suggest that even at low Reynolds number, partitioning is affected by the bifurcation angle by increasing cell-cell interactions. The presented results provide further insight into RBC partitioning as well as perfusion throughout the microvasculature.
在微血管分叉处的红细胞（RBC）分配研究方面有着悠久的历史。这些研究通常报告描述分配的结果，存在规则分配和反向分配两种情况。当 RBC 通量比大于主体流体流速比时发生规则分配，而当 RBC 通量比小于或等于主体流体流速比时发生反向分配。本文研究了在尺寸为 6 到 16μm 的单个分叉微通道中 RBC 的分配情况，考察了血细胞比容、通道宽度、子通道流量比和分叉角的影响。红细胞通量比 N表现为规则或反向分配，而时变分配则更为动态，既可以是规则分配也可以是反向分配。我们报告了红细胞通量比（N）与体积流速比（Q*）之间的著名的类正弦变化显著减少，当通道尺寸与细胞尺寸相当且血细胞比容增加时，微通道中的分配行为。还观察到并量化了 RBC 在分叉处的“滞留”或堵塞现象。轨迹分析结果表明，RBC 在进料通道中的位置强烈影响分配和 RBC 的滞留频率，当 RBC 沿通道边缘的流线流动而不是沿通道中心流动时，这两种情况都会显著减少。此外，我们的实验表明，即使在低雷诺数下，分叉角也会通过增加细胞间相互作用来影响分配。所呈现的结果为 RBC 分配以及整个微血管中的灌注提供了更深入的了解。
