Figure 4.

Directional liquid transport on biomimetic planar surfaces. (a) Liquid unidirectional transportation on peristome-mimic surface with surface tensions ranging from 9.5 to 72.0 mN m⁻¹; (b) Transformation of liquid transport direction on the V-shaped prisms. The moving directions of liquid reverse with varying arrangements of the V-shaped prisms on the elastic film; (c) Directional water transport on planar surface with a periodic Janus gradient structure inspired from the Janus wettability surface of desert beetle, the geometry gradient of cactus spines, and the periodic microcavities of Nepenthes alata; (d) The variation of the ratio between the spreading length and the spreading width as a function of spreading time. Reproduced with permission from Refs. [59,65,69,80].