Bio-inspired slippery surfaces with a hierarchical groove structure for efficient fog collection at low temperature

Many biological surfaces with hierarchical microstructures have been demonstrated to have the ability of fog collection. However, most of the current fog collection is achieved through a single structure, and the fabrication of hierarchical structures is mostly achieved through stepwise preparation. Besides, it is inevitable for the fog collector to work at low temperature environment. In this contribution, we fabricated a series of hierarchical slippery groove surfaces inspired by the surface structure of Sarracenia trichomes for efficient fog collection at low temperature, and the sample showed slippery properties after fluorination and oil injection treatments. Moreover, we evaluated the fog collection abilities of the surfaces for the condition of low temperature (0 degrees C). The results showed that the hierarchical groove surface showed better fog collection ability than the flat surface, and the oil film can hinder the heat transfer between droplet and surface, so as to prevent the droplets from freezing on the surface. So the injection of oil was essential for water transport and fog collection capabilities at low temperature. The proposed research is pioneering work in the area of functional surface towards the realization of fog collection at low temperature, one significant step towards fog collector to work under extreme condition.