Fig. 3.

Fabrication process from the original templates of butterfly wings to the SiO₂ negative replica. a 3D nanostructured model of the original butterfly wings. b The precursor solution filled the space left between the micro-ridges with a micropipettor. c The precursor solution became solidified through heating process. d The solid negative replica was obtained after the original bio-templates were etched away and cooled at room temperature