Analysis of Local Viscosity in Alginate Gel via Bead-based Diffusometry

In this study, we evaluated the microscopic viscosity of sol-gel films by observing the diffusion behavior (particle diffusivity) of fluorescent particles dispersed in colloids such as sols and gels. The dynamic viscosity was compared with the particle diffusivity for several alginate solutions of different concentrations, and it was found that the particle diffusivity and solution viscosity were correlated. Localized analysis of the inside of a gel thin film suggested that material phase changes can be evaluated by observing changes in particle diffusivity. Because the diffusion behavior of fluorescent particles was observed by microscopy, it was possible to obtain arbitrary local viscosity information from inside the material. Spatially and temporally continuous characterization of the inside of thin films made of polymeric materials can be performed by a very simple method.