Orientation and deformation of erythrocytes due to flow

Electrical resistivity change and scattering light intensity change of blood due to flow are simultaneously measured. The measurement cell consists of two concentric cylinders. The inner cylinder can rotate in order to create various patterns of Couette flow by stepping motor. On the inner surface of the outer cylinder, electrodes are arranged to measure electrical impedance in circumferential, axial and radial direction. From these experimental results, the orientation and deformation of erythrocytes is discussed. We calculated orientation ratio and deformation of erythrocytes by simplified spheroids model of erythrocyte. The orientation ratio of erythrocytes due to steady flow is calculated. This results show that the fraction of erythrocytes which are orienting their long axis parallel to each orthogonal direction changes with the shear rate of flow.