Ultrasounds to probe the microstructure of sheared suspensions of Red Blood Cells

Over the past decade, it has been shown that dense (>8%) suspensions of spherical particles in single shear flow exhibit anisotropic microstructure along the flow direction due to particle roughness. We prove that ultrasound can measure this anisotropy. For deformable and anisotropic particles such as red blood cells, this microstructure is still poorly understood.

First, using ultrasound measurements coupled with numerical simulations, I will show first results on the microstructure of disaggregated red blood cells in a simple shear flow for volume fractions up to (physiological volume fraction of) 40%.

Then, also thanks to ultrasonic measurements, I will present the characterization of blood aggregation (aggregate size, polydispersity...). Indeed, aggregation is more representative of what happens in our body in the presence of the fibrinogen protein. The clinical application is to estimate the rate of aggregation in the blood and (in the much longer term) to allow a pre-diagnosis.

Third, using optical measurements in a microfluidic channel, I will present preliminary results on the influence of RBC properties (deformability) on their microstructure and dynamics.