Researchers from the university of Surrey, UK have devised a new method to characterise the internal structures of natural materials, a capability they say could enable the engineering of complex optical functionalities in new materials. In Nature, the researchers demonstrated this intuition by fabricating 3D-printed ceramics that exhibit similar optical properties as seen on the wings of a butterfly.
The ceramic structures produced via 3D printing exhibited similar optical properties to those seen in the wings of the Pseudolycaena marsyas butterfly (Credit: University of Surrey)
The study revealed a direct relationship between the uniformity of a natural material’s internal structure and its ability to diffuse, absorb, reflect and transmit particular wavelengths of light. With this knowledge, the team were able to devise a new mathematical metric known as ‘local self-uniformity’ (LSU) to measure which structures best control the propagation of light.
‘Here we develop LSU as a measure of a random network’s internal structural similarity, ranking networks on a continuous scale from crystalline, through glassy intermediate states, to chaotic configurations,’ the team explained in the Nature publication.
The researchers demonstrated that structures with complete photonic bandgaps possess substantial LSU, and were able to produce the first ever amorphous gyroid (triamond) structure with bandgaps via ceramic 3D printing. They then showed that this particular stucturing can be found in the wings of the Pseudolycaena marsyas butterfly, 'demonstrating the subtle order achieved by evolutionary optimisation and the possibility of an amorphous gyroid’s self-assembly,’ as explained in the publication.
‘It is truly amazing that what we thought was an artificial design could naturally be present in nature,’ said lead author Dr Marian Florescu from the University of Surrey.
As with natural structures possessing amorphous gyroid characteristics, the man-made ceramic structures were able to reflect and absorb light, sound and heat wavelengths. This could lead to the design of new materials with different functionalities, according to the researchers, and the creation of heat-rejecting window films and paints to improve the energy efficiency of buildings and vehicles.
‘This discovery will impact how we design materials in the future to manipulate their interaction with light, heat and sound,’ Dr Florescu concluded.