Ring droplet formation during evaporation of a sessile water droplet on a biphilic surface

Numerous studies have investigated droplet evaporation on surfaces with different roughness and wettability values. However, most studies have focused on droplet evaporation from homogeneous surfaces at low surface temperatures (below 100 °C). In this study, we conducted droplet evaporation experiments on biphilic surfaces with different ring pattern sizes fabricated by a hybrid method consisting of the sol-gel approach and a picosecond laser system. This study investigated the droplet evaporation boiling phenomenon on these biphilic surfaces under superheated conditions. Changes in droplet geometry and inner bubble dynamics during evaporation were analyzed using a high-speed camera. A ring-shaped droplet formed during the final evaporation period. The formation of the ring enhanced the droplet evaporation efficiency. Furthermore, the experimental results from this study work were compared with the theoretical model proposed in the literature.