title: Enhancing cell-free layer thickness by bypass channels in a wall.
abstract: When blood flows near a wall, red blood cells (RBCs) drift away from the wall and a cell-free layer (CFL) is formed adjacent to the wall. Controlling the CFL thickness is important for preventing adhesion of cells in the design of biomedical devices. In this study, a novel wall configuration with stenoses and bypass channels is proposed to increase the CFL thickness. We found that the presence of bypass channels modified the spatial distribution of cells and substantially increased the CFL downstream of the stenosis. A single-bypass geometry with 5% hematocrit (Hct) blood flow showed a 1.7μm increase in CFL thickness compared to without the bypass. In the case of three bypass channels, a 3μm increase in CFL thickness was observed. The CFL enhancement was observed up to 10% Hct, but no significant enhancement of CFL was indicated for 20% Hct blood flow. The mechanism of the CFL enhancement was investigated using a numerical simulation of the flow field. The results showed that the distance between each streamline and the corner of the stenosis compared with size of RBC was important parameter in regulating CFL thickness. These results show the potential of the proposed mechanism to prevent adhesion of cells to biomedical devices.
authors.affiliation: Department of Bioengineering and Robotics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan. Electronic address: m.saadatmand@pfsl.mech.tohoku.ac.jp.
authors.forename: M
authors.initials: M
authors.lastname: Saadatmand
authors.affiliation: Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimogonya
authors.affiliation: Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Department of Bioengineering and Robotics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan; Department of Biomedical Engineering, Graduate School of Biomedical Engineering, Tohoku University, Sendai 980-8579, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ishikawa
mesh_terms: D000328:Adult; D003251:Constriction, Pathologic; D004912:Erythrocytes / Q000502:physiology*; D006400:Hematocrit; D006439:Hemodynamics; D006801:Humans; D008297:Male
keywords: Biofluid mechanics; Blood; Cell-free layer; Microfluidic device