Oota-Ishigaki Akiko, Masuzawa Toru, Nagayama Kazuaki
1 Department of Mechanical Engineering, Ibaraki University, Ibaraki, Japan.
2 Department of Intelligent Systems Engineering, Ibaraki University, Ibaraki, Japan.
Int J Artif Organs. 2018 May;41(5):277-283. doi: 10.1177/0391398818763264. Epub 2018 Mar 15.
Thrombus formation on biomaterial surfaces with microstructures is complex and not fully understood. We have studied the micro-secondary flow around microstructures that causes components of blood to adhere physically in a low Reynolds number region. The purpose of this study was to investigate the effect of micro-column size on the adhesion phenomena and show a quantitative relationship between the micro-secondary flow and physical adhesion phenomena, considering microstructures of various sizes. The flow simulation and quantitative assessment of adhesion rates around micro-columns was conducted using four sizes of micro-columns. This study also calculated the vectors of micro-secondary flow and average shear rate around a micro-column using a computational fluid dynamics analysis. The simulation showed the micro-secondary flow toward the bottom surface at upstream side and low shear rate distribution generated around a micro-column. Furthermore, physical adhesion tests were conducted using microbeads and a perfusion circuit to examine the size effect of the micro-columns on the physical adhesion. The results showed that the average adhesion rate around the micro-column increases with the associated size increase of the micro-column. Our results indicate that quantification of micro-secondary flow on a material surface with microstructures of several sizes and shapes (such as in a rough surface) is important for the evaluation of the adhesion phenomenon even though the surface roughness value on the material surface is small.
生物材料表面带有微结构时的血栓形成过程很复杂，目前尚未完全了解。我们研究了微结构周围的微二次流，这种微二次流会使血液成分在低雷诺数区域发生物理粘附。本研究的目的是研究微柱尺寸对粘附现象的影响，并在考虑各种尺寸微结构的情况下，揭示微二次流与物理粘附现象之间的定量关系。使用四种尺寸的微柱对微柱周围的流动进行模拟，并对粘附率进行定量评估。本研究还通过计算流体动力学分析计算了微柱周围微二次流的矢量和平均剪切率。模拟结果显示，在上游侧微二次流向底面流动，且微柱周围产生低剪切率分布。此外，使用微珠和灌注回路进行了物理粘附测试，以研究微柱尺寸对物理粘附的影响。结果表明，微柱周围的平均粘附率随微柱尺寸的增加而增加。我们的结果表明，即使材料表面的粗糙度值很小，对具有多种尺寸和形状微结构（如粗糙表面）的材料表面上的微二次流进行量化，对于评估粘附现象也很重要。
