Transparent butterfly wings could inspire low-reflectivity displays

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The wings of the glasswing butterfly reflect hardly any light (Image: KIT/ Radwanul Hasan Siddique)

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Researchers from the Karlsruhe Institute of Technology (KIT) in Germany have studied the wings of glasswing butterflies in an effort to determine what causes their low-reflective nature. It's believed that the findings of the study could lead to less reflective screens on mobile phones, tablets and other devices.

A flat pane of glass will reflect between eight and 100 percent of light that falls upon it, often making content difficult to view on glass-fronted displays such as those found on smartphones and tablets. The need for less reflective display technology will be readily apparent to anyone who has attempted to use a glossy-screened device in direct sunlight.

Increasingly, scientists have been turning to nature in an attempt to solve the issue. The transparent surfaces on certain animals, such as the eyes of a moth, have been found to reflect significantly less light than glossy man-made surfaces, but only when the viewing angle is vertical to the surface.

By contrast, the wings of a glasswing butterfly reflect between two and five percent of light, regardless of the viewing angle of the observer. The surface of the wings exhibits a low reflection of both visible light, as well as infrared and ultraviolet spectrums visible to certain animals. This makes the butterflies more difficult to track during flight, allowing them to better avoid the clutches of predators.

The KIT researchers set out to solve the mystery of this unstudied phenomenon, scanning the butterfly's wings via an electron microscope.

Previous studies have revealed that a series of regular pillar-like nanosctructures are responsible for the low reflective nature of transparent surfaces on animals, and similar structures were found during the KIT observations. However, unlike the uniform pillars previously observed, those found in the butterfly's wings were of varying height (between 400 and 600 nanometers) and randomly spaced, some 100 to 140 nanometers apart.

Following the observations, the researchers mathematically modeled the irregular nanopillar arrangement, with the findings matching up perfectly with the behavior of the observed light.

"In contrast to other natural phenomena, where regularity is of top priority, the glasswing butterfly uses an apparent chaos to reach effects that are also fascinating for us humans." says doctoral student and team member Radwanul Hasan Siddique.

Having solved the mystery, the team believes that the findings of the study could lead to the development of less reflective surfaces for mobile phones displays, glass lenses and more.

The results of the research have been published in the journal Nature Communications.

Source: KIT

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