LIGHT-SCATTERING TECHNIQUE FOR THE STUDY OF ORIENTATION AND DEFORMATION OF RED-BLOOD-CELLS IN A CONCENTRATED SUSPENSION

The backscattered and transmitted diagrams of He-Ne laser light illumi nating a concentrated suspension of red blood cells (RBC's) are invest igated. The shapes of these diagrams are closely related to the state of the suspension (at rest or submitted to a simple shear flow) and to the parameters that govern the non-Newtonian behavior of the blood su spension (such as the viscosity of the suspending medium and the volum e concentration of the cells). An asymmetry in the backscattering diag ram, which is absent on transmitted diagrams, is observed when the sus pension is in a simple shear flow. This asymmetry is related to the de formation and orientation of the RBC's. The propagation of light throu gh the suspension is modeled and a set of Monte Carlo simulations is p erformed to substantiate the inference that the relative variation of the backscattered flux is proportional to the gradients of deformation of the RBC's, and that such gradients must be known in order to apply a rheological model describing the non-Newtonian behavior of RBC memb ranes.