A surface with asymmetric microstructures for self-driven directional spreading of liquid has attracted keen interest from researchers in recent years for its great application prospects. Inspired by the jaws of tiny insects, such as ants, a surface textured with novel jaw-like microstructures as micro one-way valves is reported. These microstructures are almost two-dimensional, thus being simple and easy to fabricate. Whereas surfaces with such jaw-like micro one-way valves exhibit amazing rapid and long-distance water droplet unidirectional spreading behaviors. The maximum forward-backward distance ratio of water droplets on surfaces with the optimized microstructures is about 14.5, almost twice those of previous research. The capillary attraction at the location of the mouth of the jaws and the pinning effect brought by the sharp edge of the jaws for the precursor film are analyzed and deduced as the main mechanisms. The findings open a promising avenue for 2D asymmetric microstructure design and effective self-driven liquid unidirectional spreading.
Keywords: bionic surface; self-driven; unidirectional spreading; water droplet.