Bio-inspired inclined nanohair arrays with tunable mechanical properties for effective directional condensed microdroplets self-jumping.

[Display omitted] • Inclined nanohair arrays show excellent directional microdrop self-jumping. • The structure fabricated by nanoimprinting followed by oriented template removal. • Modulus and hardness influence the directional microdrop self-jumping. • Directional jumping is ascribed to the unbalanced lateral force. Anisotropic surfaces comprised of organized asymmetric nanostructures have provided the basis for diverse functions due to their direction-dependent properties, such as directional liquid self-transportation by condensed microdroplet self-jumping (CMDSJ). However, it is still a challenge to facile fabricate the organized asymmetric nanostructures to realize the directional CMDSJ. On the other hand, mechanical properties of the nanosurface is a key factor influencing the CMDSJ, which is always ignored. Here, inspired by the inclined tapered setae on the leg of water striders, inclined nanohair arrays which form a ratchet structure is facilely fabricated at low cost and large area by nanoimprinting followed by directional template removing. Microdroplets with diameter larger than 10 µm show directional CMDSJ on this surface whose mechanical properties (hardness and modulus) are strengthened by depositing silica nanoparticles. This is because the moving droplet suffers less lateral force which prevents the movement of the droplet as moving along the inclined direction of the nanohair than that moving along the opposite direction. The simulation result is corresponding to the experiment well. This work shows a facile way to obtain anisotropic structure with directional CMDSJ property and has a deep insight into how mechanical properties of the nanostructure influence the CMDSJ. [ABSTRACT FROM AUTHOR]