Viscoelasticity of the Cell Membrane Dictates Cross Stream Migration of Red Blood Cells in Micro-Confined Shear Flow

Red blood cells (RBCs) deform uniquely in human body microvasculature, enabling their dynamic evolution in complex physiological fluidic pathways. While these deformation characteristics are linked with certain diseased conditions, the explicit role of viscoelasticity of the RBC membrane remains unclear. Here, we employ a 3D lattice-Boltzmann model for elucidating the role of membrane rheology towards dictating its migration in a micro-confined shear flow, mediated by a balance between hydrodynamic forces due to tumbling and wall-induced lift forces. For a stiffer and less fluidic membrane, the RBC is observed to attain a centerline equilibrium position due to the dominance of tank-treading over tumbling kinematics, resulting in substantial wall-induced lift forces. We demarcate the parametric boundaries between centerline and off-center equilibrium configurations and highlight their implications in microvasculature flow dynamics. These results are expected to open up novel paradigms of exclusive mapping of the viscoelastic properties of RBC membrane with various physiological disorders using patient-specific data.