Effect of suspended particles on the drying process of a carrier-fluid droplet sitting on a solid surface.

We focus on an evaporation process of a volatile droplet on a temperature-controlled solid substrate. The process is strongly affected by suspending tiny particles inside the droplet, resulting in a well-known phenomenon called the "coffee stain problem." The target systems in this study are (1) the water-hydrophilic particle and (2) the water-ethanol mixture-hydrophilic particle.