Effect of Flow Around Three-Dimensional Micro-Geometric Structures on Adhesion Phenomena

Abstract

Thrombus formation on biomaterial surfaces with microstructures is complicated and not fully understood. We assumed that the micro-stagnation generated around microstructures is one factor to enhance thrombus formation. In our prediction, the micro-flow around microstructures causes blood components to adhere physically in a low Reynolds number region. The objective of this study is to investigate the micro-flow around three-dimensional micro-geometric structures and the aspects of physical adhesion affected by the micro-flow. Flow simulation and quantitative assessment of adhesion rates around micro-columns was conducted as a basic study. The particle pathlines and average shear rate around a column were calculated through computational fluid dynamics analysis. The simulation showed that low shear rate distribution caused by flow-stagnation is generated around a column, even if it is in micro-flow in a low Reynolds number region. Physical adhesion tests using micro-beads showed that the average adhesion rate around the column was higher than that in the neighboring plane area. A low shear rate region generated by microstructures may increase the potential for adhesion of substances, which enhances thrombus formation even when the scale of flow is of the order of micrometers.

Analysis of the effect of the size of three-dimensional micro-geometric structures on physical adhesion phenomena using microprint technique

“…In our previous study, we reported on the relationship between micro-flow and physical adhesion based on a hypothesis that the micro-flow around a microstructure enhances the physical adhesion phenomenon of a particle in fluid. 12 Our results showed that the microvortex generated at the upstream side of a micro-column has the possibility to enhance the physical adhesion phenomena around the column. The purpose of this study is to investigate the effect of micro-column size on the adhesion phenomena and show the quantitative relationship between the micro-secondary flow and physical adhesion phenomena around microstructures of various sizes.…”

“…The fluid in the perfusion chamber exhibited a plane Poiseuille flow. 12 The test piece was set in an 11-mm square pocket in the perfusion chamber. The test equipment was assembled as a closed circuit with the perfusion chamber, as shown in Figure 1(f).…”