Additive manufacturing of digitally programmable hierarchical biomimetic surfaces for hydrodynamic informatics

Abstract

Herein, combinatorial biomimetic hierarchical micro/nanoscale structures (HMNSs) inspired by lotus leaves and rose petals are realized on a single copper (Cu) substrate via laser-induced reductive clustering (LRC) of copper (II) oxide nanoparticles. Cu spike structures are constructed via mild LRC to imitate microscale papillae of the lotus leaf surface. Subsequently, the LRC-treated specimen is immersed in a 1H,1H,2H,2H-perfluorooctyltrichlorosilane (PFOTS) solution for emulating the high-density nanopillars on the conical microcells of the lotus leaf. The microscale surface texture for achieving the rose-petal effect is realized by forming a microporous Cuchain structure via intense LRC based on prolonged laser heating. By soaking the microporous Cu-chain structure in a PFOTS solution, the rose petal-inspired HMNS is demonstrated. The created lotus leaf- and rose petal-inspired HMNSs exhibit water rolling and droplet-pinning wetting characteristics, respectively. These HMNSs are selectively patterned and customized in a digitally programmable manner on a single Cu plate for fabricating a hydrodynamic memory device that can save and display digital data. Owing to its additive manufacturing feature, the developed LRC method could be applied to a wide spectrum of substrates ranging from glass to flexible plastics.