Figure 1. Design and fabrication of highly selective vapour sensors inspired by Morpho butterflies.

(a) Schematic of the tree-like tapered structure of natural butterfly scales with its chemical gradient of surface polarity. (b) Schematic of the fabricated nanostructure and design criteria for vapour-selectivity control. (c,d) Scanning electron microscopy (SEM) images of Morpho sulkowskyi scales and fabricated six-lamellae nanostructures. (e,f) Iridescent colouration of M. sulkowskyi scales and fabricated nanostructures. Shown in (f) are six regions of nanostructures that were fabricated with and without lamella; each region was 2 × 2 mm. On illumination with a white light, three replicate regions of nanostructures with lamella reflected blue light while three other replicate regions of nanostructures without lamella (with only ridges) reflected red light.