Development of High-Speed Birefringence Measurement System for Investigating Fluid-Structure Interaction in Hemodynamics*

Elucidation of the stress interaction between blood and blood vessels is important for understanding the phenomena of cerebral vascular diseases. One of the factors contributing to the pathogenesis is wall shear stress (WSS) induced by hydrodynamic stress of blood flowing in blood vessels. Numerical analysis for investigating WSS has been performed mainly with computational fluid dynamics (CFD), such as fluid-structure interaction (FSI). However, it is difficult to reproduce the complex phenomena of blood and blood vessels exactly in CFD. Therefore, we have developed a birefringence measurement method with a high-speed polarization camera to experimentally understand the stress interaction between blood and blood vessels. Birefringence is the physical quantity of polarized light and is proportional to stress. In the present study, the stress fields of solid (elastic channel) and liquid (working fluid) which simulate the elasticity of blood vessels and shear-thinning characteristics of blood, respectively, were visualized. Moreover, the visualization of WSS interaction between the simulated blood and blood vessels based on the birefringence data was performed.