The coalescence and guided transport of droplet have many applications in micro-fluidics, printing, oil-water separation, atmospheric water harvesting, heat transfer, and anti-icing. Though studies of macrodroplets transport have been reported in previous literatures, there is still a research vacancy about guided transport of micordroplet without any external forces. 

Institute of Chemistry of the Chinese Academy of Sciences (ICCAS) research group headed by Prof. WANG Jianjun made a progress in the guided self-propelled transport of microdroplets. By introducing anisotropic micropatterns on a superhydrophobic surface, they demonstrated for the first time that water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction. This work was published on Angew. Chem. Int. Ed. 2016, 55, 4265-4269. 

The micro-anisotropic structures give rise to an asymmetric work of adhesion on the superhydrophobic surface, which works as a steering force for leaping microdroplets. The capability of guided leaping of microdroplets is mainly determined by the geometric parameters of micro-structure and the droplet size. 

Due to the periodic anisotropic work of adhesion, the designed surface demonstrated a cumulative effect on guiding droplet. According to this, researchers have achieved relatively long-distance transport of microdroplets by “relay” coalescence-induced leaping. This also indicates that the designed surfaces would have potential applications on effective self-sustained micro-carrier and much enhanced performance for heat, mass and energy transfer. 

This work is financially supported by the 973 Program and the National Natural Science Foundation of China. 

Water microdroplets can coalesce and leap over the surface spontaneously along a prescribed direction by introducing anisotropic micro-patterns on superhydrophobic surfaces. Self-powered, and relatively long-distance transport of microdroplets by “relay” coalescence-induced leaping. （Image by Prof. WANG Jianjun） 

Contact: 

Prof. WANG Jianjun 

Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, 

Email: wangj220@iccas.ac.cn