The study, published in Bioinspiration & Biomimetics (doi: 10.1088/1748-3182/4/3/034001), could have many applications, such as in optical diffusers and coverings that maximize solar cell light absorption, as well as in fabrics, textiles and surfaces based on the nanoscale photonic structures responsible for the vibrant colors in many butterfly wings. It could also be possible to have swatches of fabrics that would sense such things as magnetic fields and temperature changes.
Insects' colours and their ability to change colours depending on the angle, or their ability to appear metallic, are determined by tiny nano-sized photonic structures that can be found in their cuticle. The research has focused on these biostructures to develop devices with light-emitting properties. The team of Akhlesh Lakhtakia, Raúl Martín-Palma, Michael Motyka and Carlo Pantano, studied successful natural systems with the aim of deriving the essential design elements, and hence improve man-made systems.
As Lakhtakia points out, there is the possibility of “replicating highly convoluted surfaces down to the smallest feature size, thereby reproducing some of their most desired optical, electronic, mechanical and chemical functionalities.”
Up to now, the few methods that can be used to replicate biostructures on a nanometric scale often damage the original biostructure, because they are used in corrosive atmospheres or at high temperatures. This new technique overcomes these problems, as it is employed at room temperature and does not require the use of toxic substances.
In order to create new biomaterial, the team employed a technique called conformal-evaporated-film-by-rotation (CEFR), which combines thermal evaporation and substrate rotation in a low-pressure chamber to replicate the surface, and used immersion in an aqueous orthophosphoric acid solution to dissolve the chitin.
As well as butterfly wings, the compound eyes of insects such as flies, bees and wasps are also possible sources for a range of new applications, including miniature cameras and optical sensors installed in cars, mobile telephones and displays. There is also potential for use in surgical procedures and the security industry. The scientists are confident that the technique can also be used to replicate other biological structures, such as beetle shells.
The researchers admit that only bio-replication that could be scaled up and not deplete natural populations of the species whose surfaces are being replicated is going to be industrially viable, humane and ethical. However, they are confident that they can achieve this through the further study of biostructures.