Visualization Studies on Drying Patterns of Hydrogel Droplets

The phenomenon of droplet dynamics is widely seen in both natural and industrial contexts, including but not limited to spray painting, fuel injection, printing industries, and forensics. However, a deeper understanding of the governing factors is necessary in order to comprehend the various characteristics displayed by droplets in different applications. In the context of bio-applications, the natural drying process is distinguished by the physiochemical parameters of the fluid, including density, viscosity, and the presence of additives. The relationship between viscosity and applied shear rate, as well as surface properties, is particularly noteworthy in the context of complicated fluids. This study used two distinct additives, namely CaSo4 and Xanthan gum, to investigate the wetting and drying mechanisms of multicomponent fluids. The earlier is a simple bi-component solution that results in the formation of amorphous powder. In contrast, the Xanthan gum-based complex fluids exhibit shear-thinning behaviour and display distinct drying patterns. The drying patterns are found to be influenced by Marangoni effects, which arise as a consequence of mass transfer. The experimental findings indicate that the drying patterns, ranging from the formation of a coffee ring pattern to complete wetting, are influenced by the composition of the solution. Furthermore, rheological studies are necessary to understand the response features of additives in the drying behaviour of shear-thinning fluids.