Cyphochilus is agenus ofbeetles with unusually brightwhitescales that cover the wholeexoskeleton.Cyphochilus inhabitSoutheast Asia.[1]
Probably the same etymology as the formerCyphochilus orchid: from the Greekkyphos meaning "bent" andcheilos meaning "lip", because of the reflexed lip.[2]
The whiteness of the scales is caused by a thin disorderedphotonic structure (≈7 μm) which scatters light of allwavelengths with the same efficiency, thus resulting in awhite colouration. This is particularly interesting as the beetle's exoskeleton underneath the scales is black, meaning that the scattering events must be very efficient in order to achieve such high opacity.[3]
The white scales are composed ofsclerotin, a modified form of the polymerchitin, and are whiter than paper or any artificial material produced as of 2022. That is they have a scattering mean free path shorter than any natural material thanks to the anisotropy in the spatial architecture of the fibres, which ensures a high packing efficiency whilst preventing optical crowding.[4]
The beetles are believed to have developed white coloration to camouflage themselves among whitefungi. The chitin filaments are just a fewmicrometres thick – far thinner than a very fine sheet of paper. The elements are tightly packed,[5] scattering light efficiently, but still able to keep a degree of disorder in their shape.[6] It has been shown how this strategy is evolutionarily optimised to produce bright whiteness despite the low refractive index ofsclerotin.[7]
Scientists have exploited thetopology of therandom network to fabricate materials of comparable performance for application as ultra-white paints and coatings. For instance, in 2018 Syurik et al. have developed a bioinspiredPMMA-based material that scatters light efficiently and is flexible and switchable in appearance.[8]
Another recent example consists of the use ofcellulose nanofibrils to fabricate ultra-white paper for cosmetics and coatings.[9] Or ceramic for tiles.[10]
In 2023 a durablealumina-based ceramic based onCyphochilus achieved a solar reflectivity of 99.6%, a record high, along with infrared thermal emission of 96.5%. It tolerates ultraviolet light and increases water evaporation and withstands temperatures of over 1,000 °C.[11]
Finally, the researchers also say that the material can be easily mass produced, using common materials like alumina and a two-step process of phase inversion and sintering. And if white is too boring for some houses, the material can apparently be produced in other colors and patterns by adding extra layers.
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