Delicate butterfly wings replicated

A team of researchers have developed a technique to replicate biological structures, such as butterfly wings, on a nano scale and say the resulting biomaterial could be used to make optically active structures, such as solar panels

Replicating the nanostructure of butterfly wings could give us new solar panels

Insects' colours and their iridescence (the ability to change colours depending on the angle) or their ability to appear metallic are determined by tiny nano-sized photonic structures which can be found in their cuticle. The team from the US focused on these biostructures to develop devices with light emitting properties.

“This technique was developed at the Materials Research Institute of the State University of Pennsylvania and it enables replicas of biological structures to be made on a nanometric scale,” said Raúl J. Martín-Palma lead author of the paper in the journal Bioinspiration & Biomimetics.

The researchers have created free-standing replicas of fragile, laminar, chitinous biotemplates - that is, copies of the nano structures of butterfly wings. The appearance of these appendices usually depends more on their periodical nanometric structure - which determines the "physical" colour - than on the pigments in the wings - which establish the "chemical" colour.

In order to create new biomaterial, the team used compounds based on Germanium, Selenium and Stibium (GeSeSb) and employed a technique called Conformal-Evaporated-Film-by-Rotation (CEFR), which combines thermal evaporation and substrate rotation in a low pressure chamber. They also used immersion in an aqueous orthophosphoric acid solution to dissolve the chitin.

Martín-Palma points out that the structures resulting from replicating the biotemplate of butterfly wings could be used to make various optically active structures, such as optical diffusers or coverings that maximise solar cell light absorption, or other types of devices. "Furthermore, the technique can be used to replicate other biological structures, such as beetle shells or the compound eyes of flies, bees and wasps," the researcher says.