Current Research: Hemorheology in Microchannels

Red blood cell size, deformability, and aggregation behavior vary significantly across vertebrate species.  Unlike mammals, oviparous vertebrates (birds, reptiles, amphibians) have nucleated red blood cells.  Data from: (1) Gulliver, G. Proceedings of the Zoological Society of London 1862: 91-103 and (2) Arikan, H., and C. Kerim. Northwestern Journal of Zoology 2014 10(1):190-209.

Red blood cell size, deformability, and aggregation behavior vary significantly across vertebrate species.  Unlike mammals, oviparous vertebrates (birds, reptiles, amphibians) have nucleated red blood cells.  Data from: (1) Gulliver, G. Proceedings of the Zoological Society of London 1862: 91-103 and (2) Arikan, H., and C. Kerim. Northwestern Journal of Zoology 2014 10(1):190-209.

We often consider the flexible, biconcave human erythrocyte (red blood cell) as "perfectly" suited for the variety of flow conditions it will encounter in vivo, from Reynolds number of ~2000 near the heart  to contorting through capillaries nearly half the cell's diameter.  However, current fluid dynamics literature largely ignores both the significant variation in erythrocyte size across mammalian species (~4-12 microns) as well the shape variation seen in oviparous vertebrates.  In addition, within channel diameters of 10-300 microns, blood exhibits unique behaviors via the Fahraeus and Fahraeus-Lindqvist effects.  We seek to understand  the role of erythrocyte size and shape within the context of these effects with the goal of better control and manipulation of blood flow in microfluidic devices.

Optical micrographs of blood samples used in our pressure drop experiments.  Blood samples are treated with K2 EDTA as an anticoagulant.  Note the differences in red blood cell aggregation (clumping and formation of rouleaux) across species - this is one factor affecting whole blood viscosity at low shear rates.

Optical micrographs of blood samples used in our pressure drop experiments.  Blood samples are treated with K2 EDTA as an anticoagulant.  Note the differences in red blood cell aggregation (clumping and formation of rouleaux) across species - this is one factor affecting whole blood viscosity at low shear rates.