Research News
[Prof. Seung Hwan Ko] Biomimetic reconstruction of butterfly wing scale nanostructures for radiative cooling and structural col
Author
김민아
Date
2024-04-29
Views
133
Abstract
A great number of butterfly species in the warmer climate have evolved to exhibit fascinating optical properties on their wing scales which can both regulate the wing temperature and exhibit structural coloring in order to increase their chances of survival. In particular, the Archaeoprepona demophon dorsal wing demonstrates notable radiative cooling performance and iridescent colors based on the nanostructure of the wing scale that can be characterized by the nanoporous matrix with the periodic nanograting structure on the top matrix surface. Inspired by the natural species, we demonstrate a multifunctional biomimetic film that reconstructs the nanostructure of the Archaeoprepona demophon wing scales to replicate the radiative cooling and structural coloring functionalities. We resorted to the SiO2 sacrificial template-based solution process to mimic the random porous structure and laser-interference lithography to reproduce the nanograting architecture of the butterfly wing scale. As a result, the biomimetic structure of the nanograted surface on top of the porous film demonstrated desirable heat transfer and optical properties for outstanding radiative cooling performance and iridescent structural coloring. In this regard, the film is capable of inducing the maximum temperature drop of 8.45 °C, and the color gamut of the biomimetic film can cover 91.8% of the standardized color profile (sRGB).
Conclusions
Inspired by the biological source, we developed a multifunctional biofilm that imitates the nanostructure of the Archaeoprepona demophon wing scale that exhibits radiative cooling and structural coloring functionalities by modulating the infrared absorbance and visible reflection level. We devised two different, cost-effective fabrication strategies for ridge and porous structures and integrated them to artificially reconstruct the butterfly wing scale. For the porous structure, we used a solution-based process that removes SiO2 nanospheres of different sizes to make an inverse opal structure. Coupled with the radiative cooling material property of PVDF-HFP, the random multi-porous structure plays a dominant role in maximizing the radiative cooling performance of butterfly species. On the other hand, for the ridge structure, we resorted to laser interference lithography to fabricate a periodic nanograting surface on which a soft elastomer can be imprinted to mimic the ridge structure of Archaeoprepona demophon. The ridge structure serves to generate structural coloring that mimics the visual appearance of the butterfly wing scale. Integration of porous and ridge structures resulted in radiative cooling and structural coloring functionalities of the butterfly wing scale, as it recorded the maximum radiative cooling temperature of 8.45 °C, while we imprinted the ridge structure with different grating distance so that each region with a different imprint generates distinctive color. Overall, we expect that the biomimetic film developed herein would not only offer us a clearer experimental insight into the structure–functionality relationship of the Archaeoprepona demophon wing scale, but it would also make substantial contributions to the state-of-the-art radiative cooling technologies that have the potential to address climate change.More Information : Biomimetic reconstruction of butterfly wing scale nanostructures for radiative cooling and structural coloration - Nanoscale Horizons (RSC Publishing)
