A two-in-one superhydrophobic and anti-reflective nanodevice in the grey cicada $\textit{Cicada orni}$ (Hemiptera)

TL;DR

This study uncovers a nanostructure on the grey cicada's wings that provides both superhydrophobicity and anti-reflective properties, combining experimental, imaging, and modeling techniques.

Contribution

It identifies and characterizes the dual-function nanostructure on cicada wings, demonstrating its roles through experiments and simulations.

Findings

Nanostructure responsible for superhydrophobicity

Nanostructure enhances anti-reflective behavior

Refractive index of wing material determined

Abstract

Two separated levels of functionality are identified in the nanostructure which covers the wings of the grey cicada $\textit{Cicada orni}$ (Hemiptera). The upper level is responsible for superhydrophobic character of the wing while the lower level enhances its anti-reflective behavior. Extensive wetting experiments with various chemical species and optical measurements were performed in order to assess the bi-functionality. Scanning electron microscopy imaging was used to identify the nanostructure morphology. Numerical optical simulations and analytical wetting models were used to prove the roles of both levels of the nanostructure. In addition, the complex refractive index of the chitinous material of the wing was determined from measurements.