Paper Number
BF22 

Session
Biomaterials and Bio-fluid Dynamics

Title
Aggregation and break up of red blood cell aggregates in (complex) flow

Presentation Date and Time
October 11, 2022 (Tuesday) 5:05

Track / Room
Track 4 / Michigan AB

Authors (Click on name to view author profile)

  1. Lettinga, Minne P. (Leuven)
  2. Korculanin, Olivera (Forschungszentrum Jülich, IBI-4)
  3. Babaki, Mehrnaz (Forschungszentrum Jülich, IBI-4)
  4. Gholivand, Amirezza (forschungszantrum Jülich, IBI-4)

Author and Affiliation Lines (in printed abstract book)
Minne P. Lettinga1, Olivera Korculanin2, Mehrnaz Babaki2 and Amirezza Gholivand2
1Leuven, Leuven, Belgium; 2IBI-4, Forschungszentrum Jülich, Jülich, Germany

Speaker / Presenter 
Lettinga, Minne P.

Keywords
experimental methods; bio-fluids; biomaterials; rheometry techniques

Text of Abstract
The flow of blood through the microvasculature of our brain is complex due to two main reasons: the complex geometry and the aggregation of Red Blood Cells (RBCs) into connecting stacks of RBCs, causing a strong shear thinning behavior. A bottom-up understanding of blood flow thus requires that the complexity is reduced. We first discuss the breakup of aggregates consisting of two RBCs (a doublet) under shear flow. To induce aggregation, we replace the traditionally used dextran by filamentous fd bacteriophage, which acts as an ideal rod-like depletant agents, contrary to dextran that also causes bridging. Sheared doublets are visualized by combining a home-build counter-rotating cone-plate shear cell with microscopy imaging. With increasing interaction forces, i.e. at high concentration of fd, full-contact flow states dominate, such as rolling and tumbling. We show that the RBC doublets can only undergo separation during tumbling, but the time window in which separation should take place reduces with increasing shear rates. As a result, we observed that doublets do not break up at high shear rates and infer that full break up can only occur in complex geometries [1]. Therefore, we produced novel 3-D microfluidic channels with two sequential bifurcations where the second bifurcation is in the same plane or out of the plane of the first bifurcation. To this end we use a novel technique, Selective Laser-induced Etching (SLE), which can produce 3D structures in glass with any desirable shape. Thus, we replace traditionally used 2D channels with more physiological geometries. The flow senses the orientation of downstream bifurcations, as witnessed by a shift in maximum velocity, but only in presence of aggregation. Though we do see break up at physiological rates, the geometry is not complex enough to guarantee full disaggregation. [1] Korculanin et al, Competition Between Red Blood Cell Aggregation and Breakup: Depletion Force due to Filamentous Viruses vs. Shear Flow, Front Phys-Lausanne, 2021 9.