Effects of shear rate and suspending medium viscosity on elongation of red cells tank-treading in shear flow

摘要

Elongation measurements of red cells subjected to simple shear flow are usually performed using a single suspending medium (viscosity η_0) and varying the mean shear rate γ?. Such data are often plotted versus the shear stress τ η_0γ? suggesting that the elongation scales with τ In this work, normal blood samples were tested in a rheoscope varying both η_0 and γ?. The ranges of γ? were chosen to restrict the elongation of the red cells to low values where the behavior is dominated by their intrinsic properties. It was found that the elongation scales with η_0~sγ? with s decreasing from two at η_0 = 20 mPas to unity at η_0 = 70 mPas. Above η_0 = 70 mPas, the elongation is therefore essentially determined by the membrane elasticity alone. A side observation was a large variation of the elongation both intraindividually and interindividually.