Imaging and investigation of function(s) and efficiency of ordered cuticular nanostructures (an entomological study)

Abstract

Atomic force and electron microscopy, together with the measurement of frictional and adhesive properties, have been used to determine the function(s) and efficiencies of periodic nano-structures on the surface of cicada wings. The structures consist of hexagonal close-packed protrusions with a lateral spacing of ca. 200 nm and height of ca. 225 nm. The structures are reminiscent of protrusions discovered on the corneal surface of some moths [Bernhard el al. 1963]. In that early investigation protrusions have been ascribed to evolutionary adaptation and survival value as camouflage against predators. Our study demonstrates multiple functions of the arrays. Not only do the structures confer survival value by virtue of camouflage, but they also serve as promoters of super-hydrophobicity. Both effects have been demonstrated by AFM-induced surface alteration, which show that anti-reflection and super-hydrophobicity are directly related to the geometry and chemistry of the structures.