Microdroplet self-driven transport on the surface with a bionic coupled cone-gradient groove

Abstract

Due to the illegal discharge of organic wastewater, the amount of oil-containing water is increasing. Therefore, how to quickly and effectively carry out oil–water separation has become an urgent problem. Inspired by the gutter structure of ginkgo leaves and the conical structure of pine needles, we fabricated a bionic coupled cone-gradient groove (BCGG) using micro–nano precision 3D printing technology. Under the combined effect of Laplace pressure and capillary force, the surface can perform oil–water separation spontaneously, efficiently and rapidly, with the maximum transport speed reaching 55.2 mm s⁻¹, which is approximately 11 times that of the traditional conical structure. The structure can perform anti-gravity transport of oil droplets in different environments such as gas phase, liquid phase and gas–liquid phase, while maintaining excellent transport performance for large volumes of oil droplets. This study has certain reference significance for microdroplet manipulation, liquid separation and transportation.