Scientists use 3D printing to produce butterflies in all colors of the visible spectrum

Researchers at ETH Zurich have created artificial pigments by 3D printing certain butterfly-inspired nanostructures. This principle can later be used to make color screens.

For their new technology,
biology
Scientists in the group of chemical engineering professor Andrew deMello took inspiration from butterflies. The Cynandra opis species native to tropical Africa has brilliantly colored wings. These result from extremely complex regular surface structures in the visible wavelength range. By deflecting light, these structures can amplify or cancel out the light’s individual color components. Led by deMello, the researchers successfully replicated the surface structure of Cynandra opis as well as other modifications using nano-3D printing technology. In this way, they created an easy-to-use principle for producing structures that produce structural color.

There are many examples of this type of structural coloration in nature, including irregular surface structures – found, for example, in other butterfly species. “However, the regular nanostructures on the wings of Cynandra opis are particularly suitable for use3D printingreconstruction,” explains Xiaobao Cao, a former doctoral student in deMello’s group and lead author of the study. The Cynandra opis structure consists of two grid layers stacked perpendicular to each other, with a lattice spacing of about 1/2 to 1 micrometer.

By varying this lattice spacing and the height of the lattice rods in the range of 250 nanometers to 1.2 micrometers, the ETH researchers were able to produce 3D printed structures capable of generating all colors of the visible spectrum. Many of these colors do not appear in the natural model (the butterfly) on which their structure is based.
The researchers successfully produced the surface using different materials, including transparent polymers. “This makes it possible to illuminate the structure from behind to present the color,” explains Stavros Stavrakis, a senior scientist in deMello’s group and co-author of the study. “This is the first time we’ve managed to generate all the colors of the visible spectrum as structural colors in a translucent material.”

As part of the research, the scientists created a tiny image of multi-tone structural color pixels measuring 2 x 2 microns. These tiny images could one day be used as security features on banknotes and other documents. Because color can be produced from transparent materials, color filters for optical technology can also be produced. This fits very well with the main research activity of the group of ETH professor deMello, which develops microfluidic systems – miniaturized systems for chemical and biological experiments.

Large-scale production of nanostructures is also conceivable, the researchers said. Negative structures can be 3D printed as templates, allowing the production of large numbers of replicas. This means that the principle may be suitable for making high-resolution color displays, such as bendable thin screens. Finally, scientists point out that structural colors could replace pigments used in printing and painting today. Structural colors have certain advantages over traditional pigments: they last longer because they don’t fade in light, and in most cases they have a better environmental footprint.

(responsible editor: admin)