2024 Postdoctoral Fellow Poster Award

Morphology, repulsion, and ordering of red blood cells in viscoelastic confined flows

1. Recktenwald, Steffen M. (Okinawa Institute of Science and Technology Graduate Univers, Micro,Bio,Nanofluidics Unit)
2. Rashidi, Yazdan (Saarland University, Department of Experimental Physics)
3. Graham, Ian (University of Pennsylvania, Department of Mechanical Engineering and Applied Mechanics)
4. Arratia, Paulo E. (University of Pennsylvania, Mechanical Engineering and Applied Mechanics)
5. Del Giudice, Francesco (Swansea University, Department of Chemical Engineering)
6. Wagner, Christian (Saarland University)

Abstract

Blood is mainly comprised of red blood cells (RBCs) that determine the unique flow properties of blood in the circulatory system. RBCs, the primary carrier of oxygen in the body, also play a crucial role across several biomedical applications while also being an essential model system of a deformable object in the microfluidics and soft matter fields. However, RBC behavior in viscoelastic liquids, which holds promise in enhancing microfluidic diagnostic applications, remains poorly studied. In this study, we show that using viscoelastic polymer solutions as a suspending carrier causes changes in the clustering and shape of flowing RBC in microfluidic flows compared to a standard Newtonian suspending liquid. Additionally, when the local RBC concentration increases to a point where hydrodynamic interactions take place, we observe the formation of equally-spaced RBC structures, resembling the viscoelasticity-driven ordered particles observed previously in the literature, thus providing the first experimental evidence of viscoelasticity-driven cell ordering. The observed RBC ordering, unaffected by polymer molecular architecture, persists as long as the surrounding medium exhibits shear-thinning, viscoelastic properties. Complementary numerical simulations reveal that viscoelasticity-induced repulsion between RBCs leads to equidistant structures, with shear-thinning modulating this effect. Our results open the way for developing new biomedical technologies using viscoelastic liquids while also clarifying fundamental aspects related to multibody hydrodynamic interactions in viscoelastic microfluidic flows.