Development of solid–liquid birefringence method targeting dynamic stress interactions between vascular phantom and blood analogue

The primary objective of this study is to enhance the understanding of hemodynamics by developing innovative experimental techniques that elucidate the interactions between solid and liquid stresses within circular vascular phantoms and their blood analogues. The non-Newtonian behavior of blood, coupled with the elastic properties of vascular structures, creates a complex fluid–structure interaction that poses challenges for the comprehensive analysis of stress fields using conventional numerical and experimental methods. To experimentally investigate the dynamic stress interactions between solids and liquids, we propose a novel noncontact, unsteady optical system for measuring dynamic stress fields. This system leverages a dynamic birefringence field measurement method that incorporates a high-speed polarization camera, as refined in our previous studies. Based on the stress-optic law, the measured birefringence field exhibited a spatial intensity distribution that mirrored that of the stress field. The validity of this relationship in fluids was confirmed by fluid birefringence field measurements taken using a rigid circular channel. This innovative approach enables the quantitative assessment of solid–liquid birefringence interactions within a birefringent polymer gel channel and a birefringent nanocellulose dispersion, simulating the elasticity of vascular walls and the shear-thinning behavior of blood, respectively. Moreover, the proposed method successfully visualizes dynamic birefringence fields within vascular phantoms and blood analogues under cardiac cycle-mimicking pulsatile flow, demonstrating its potential for unsteady stress measurements in solid–liquid systems. By overcoming the previously daunting challenge of visualizing dynamic stress interactions between solids and liquids, the proposed technique holds immense promise for advancing our understanding of hemodynamic phenomena.