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

Abstract

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.

Design of a microfluidic chip consisting of micropillars and its use for the enrichment of nasopharyngeal cancer cells

“…2 illustrates that in an staggered arrangement, the fluid flowed through the centre of the array, and little fluid flowed around the columns. The majority of the fluid was concentrated around the staggered column, the so-called ‘flow around the column’ phenomenon (21). Therefore, the staggered arrangement was superior to that of the aligned arrangement of columns for fluid flow through the microchip.…”