Asymmetry of light backscattering from Couette flow of RBC suspensions: application for biomonitoring of blood samples

Asymmetry of light backscattering from a shear flow of 1 mm thick layer of whole blood was measured. The blood samples from different healthy and diseased individuals were placed in a gap of a cylindrical Couette cell with inner cylinder rotating with variable rates. Probing was performed with a CW He-Ne laser (633 nm). The difference in intensities of backscattered light detected through a transpatent wall of the stationary outer cylinder with a photodetector located at variable distances from the illuminating beam along and opposite to the flow directions depends on the distance between the illuminating and detecting probes, on shear rate, on hematocrit, and on the type of a disease. The experiments conducted with blood samples from patients suffering fram heart disease, bronchial asthma, and reumatoid arthritis showed stable and reproducible difference in the amount of asymmetry. This makes the technique potentially applicable for optical biomonitoring and, also, for the study of rheology of concentrated suspentions of large deformable particles, like erythrocytes.