Cell exclusion in couette flow:evaluation through flow visualisation and mechanical forces


Cell exclusion is the phenomenon whereby the hematocrit and viscosity of blood decrease in areas of high stress. While this is well known in naturally occurring Poiseuille flow in the human body, it has never previously been shown in Couette flow, which occurs in implantable devices including blood pumps. The high-shear stresses that occur in the gap between the boundaries in Couette flow are known to cause hemolysis in erythrocytes. We propose to mitigate this damage by initiating cell exclusion through the use of a spiral-groove bearing (SGB) that will provide escape routes by which the cells may separate themselves from the plasma and the high stresses in the gap. The force between two bearings (one being the SGB) in Couette flow was measured. Stained erythrocytes, along with silver spheres of similar diameter to erythrocytes, were visualized across a transparent SGB at various gap heights. A reduction in the force across the bearing for human blood, compared with fluids of comparable viscosity, was found. This indicates a reduction in the viscosity of the fluid across the bearing due to a lowered hematocrit because of cell exclusion. The corresponding images clearly show both cells and spheres being excluded from the gap by entering the grooves. This is the first time the phenomenon of cell exclusion has been shown in Couette flow. It not only furthers our understanding of how blood responds to different flows but could also lead to improvements in the future design of medical devices.

Publication DOI: https://doi.org/10.1111/j.1525-1594.2012.01561.x
Divisions: College of Engineering & Physical Sciences > School of Engineering and Technology > Mechanical, Biomedical & Design
College of Engineering & Physical Sciences
College of Health & Life Sciences > School of Biosciences
College of Health & Life Sciences > Chronic and Communicable Conditions
College of Health & Life Sciences
College of Health & Life Sciences > School of Biosciences > Cellular and Molecular Biomedicine
Additional Information: Leslie, L. J., Marshall, L. J., Devitt, A., Hilton, A., & Tansley, G. D. (2013). Cell exclusion in couette flow: evaluation through flow visualisation and mechanical forces. Artificial organs, 37(3), 267-275., which has been published in final form at http://dx.doi.org/10.1111/j.1525-1594.2012.01561.x © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.
Uncontrolled Keywords: erythrocytes,hemolysis,hemorrheology,packed red-cell volume,ventricular assist device,Biomaterials,Biomedical Engineering,Bioengineering,Medicine (miscellaneous)
Publication ISSN: 1525-1594
Last Modified: 27 May 2024 07:10
Date Deposited: 04 Mar 2015 14:15
Full Text Link: http://onlineli ... 1561.x/abstract
Related URLs: http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2013-03
Published Online Date: 2013-01-29
Authors: Leslie, Laura J. (ORCID Profile 0000-0002-7925-9589)
Marshall, Lindsay J. (ORCID Profile 0000-0001-7281-7974)
Devitt, Andrew (ORCID Profile 0000-0002-4651-6761)
Hilton, Andrew
Tansley, Geoff D.



Version: Accepted Version

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