Flow field characterisation of aggregating human blood in bifurcating microchannels

Abstract

Erythrocyte aggregation is a shear dependent physiological phenomenon that modifies local properties of blood flow. Blood flow characteristics in microvascular bifurcations are dependent on many parameters; however the influence of erythrocyte aggregation has not been investigated previously in vitro. In the present study, micro-PIV is used to provide high spatial resolution velocity data for both erythrocytes and suspending medium for aggregating and non-aggregating human blood samples in a microchannel with a T-bifurcation geometry on the scale of the microcirculation. Simultaneous hematocrit distributions are inferred from brightfield images. Full field shear distributions are described for an evenly split flow and single flow rate. Velocity profiles of cells upstream of the bifurcation are found to be less blunt than those of the suspended particles. Daughter branch velocity profiles downstream of the bifurcation are skewed towards the wall closest to the parent branch, and non-aggregating cell velocities are significantly less blunted than those of the aggregating case. The local hematocrit is increased at the channel wall opposite the parent branch and a cell-depleted layer is observed near the channel wall closest to the parent branch. Thus, it is shown that aggregation influences both hematocrit and velocity distributions around and downstream of a bifurcation.