A study of functional micro/nano structural surfaces in bionic applications

Increasing research attentions have been paid to the bionic structures and functional materials in recent years. In order to gain the insights into functional micro/nano-structures and hence form the theoretical basis for design and fabrication of such micro/nano-structural surfaces, this paper conducts a preliminary research study on functional micro/nano structural surfaces. A short review is firstly undertaken for the existing functional micro/nano structures in bionics, and then an analytical model for the Nepenthes Alata's peristome surface is proposed, as an example, which is applicable for production by ultra-precision machining technology. In the short review, existing functional structural surfaces are classified into three categories: structural surfaces with anti-adhesive properties, environmental adaptability structural surfaces, and biological structures with other specific functions. Research work for the above three categories are reviewed: (a) The structural surface with anti-adhesive properties. Super-hydrophobic self-cleaning surface inspired by lotus effect, low friction surface inspired by shark skin, as examples, are introduced and explained. Such structural surfaces have wide and promising applications in the fields of transportation, self-cleaning materials, biomedicine and so on. This has gained intensive interest from research and industry; (b) Environmental adaptability structural surface. The formation mechanism and its application of biological colors with broad military application prospects are reviewed and introduced; (c) Biological structure with specific functions. The latest research progress of insect compound eyes, desert beetle back surface, spider silk, peristome surface of Nepenthes alata and other structures are reviewed in this part. After that, the mechanism of unidirectional liquid spreading without extra energy input on the peristome surface of Nepenthes alata was further investigated, and the structures are also designed to improve the functions based on the existing research which is on the structures of the Nepenthes with one of the typical structures having the function of directional transport without extra power supply. Furthermore, a bionic design model was proposed and the model parameters were analyzed and optimized to achieve better functional performance. Future study for functional micro/nano structural surfaces is also suggested in the end of the paper.