Aggregation and deformation of red blood cells as probed by a laser light scattering technique in a concentrated suspension: comparison between normal and pathological red blood cells

Changes in aggregability and/or deformability of red blood cells (RBC) can cause severe complications in blood circulation. We use a laser light scattering technique, which can distinguish between normal and pathological RBCs by studying the angular distributions of backscattered and transmitted light of concentrated suspensions of RBCs submitted to a simple shear flow. In order to study the deformation, we induced partial rigidity in the RBC membrane, and showed that the gradients of deformation and the relaxation times of normal and partially rigidified RBC membranes can be quantified using a non-Newtonian rheological model. We observe that blood aggregation of patients with `microcirculatory' diseases, such as diabetes, differs from that of healthy individuals.