[Journal of Materials Chemistry A] Uni-directional Liquid Spreading Control on Bio-inspired Surface
Uni-directional liquid spreading without energy input has gained much attention due to their potential applications such as microfluidic device and energy field. Recently, continuous uni-directional liquid spreading with fast speed was discovered on the peristome of Nepenthes alata, which possesses superhydrophilic hierarchical microgrooves and duck-billed microcavities with arc-shaped edge and gradient wedge corner. Inspired from the surface structure on peristome, a novel bio-inspired uni-directional liquid spreading surface with various arc curvature and wedge angle was built via two-step inclined UV exposure photolithography. The effect of the surface wettability and structural features, i.e. arc-shaped outline and wedge corner of microcavity, on the anisotropy of liquid spreading was investigated. The underlying mechanisms was made clear by comparing the effects of surface wettability and structural features of microcavity on both liquid spreading ability and liquid pinning ability. Finally, the controlling of anisotropic liquid spreading and thorough uni-directional liquid spreading were realized. This study provides inspiration to design novel uni-directional liquid spreading surface without energy input, and can further expand its applications such as non-powered deliver system, microfluidic devices and self-lubrication in mechanical engineering.
Huawei Chen, Liwen Zhang, Yi Zhang, Pengfei Zhang, Deyuan Zhang and Lei Jiang
J. Mater. Chem. A, 2017, Accepted Manuscript