Analysis of Cyclic Deformation of Erythrocyte in Couette Type of Pulsatile Shear Field

The cyclic deformation of an erythrocyte has been measured microscopically in the pulsatile shear field to detect dynamic deformability of an erythrocyte in vitro. A rheoscope system has been manufactured to observe deformation of suspended erythrocytes in the shear flow. The rheoscope consists of a pair of parallel disks and an inverted phase-contrast microscope. The human erythrocytes were suspended in the dextran aqueous solution, which has high viscosity. Erythrocytes are sheared in the Couette flow between the pair of counter rotating disks. The rotating speed varies sinusoidally to make the pulsatile shear field. Deformation of each erythrocyte was measured at the video image of the rheoscope. The experimental results show that the system is available to measure the following behavior of an erythrocyte. The ellipsoidal shape of each erythrocyte varies cyclically to follow the pulsatile cyclic shear field. The phase of deformation of each erythrocyte in the cycle delays from the sinusoidal fluctuation of the shear field according to its own dynamic deformability.