Moth eye technology could help you read your smartphone in the sun

Smartphones often aren't easy to read outside
Smartphones often aren't easy to read outside Credit: David Rose

A stealth trick used by moths to avoid predators could lead to smartphones and tablets that are easier to read outside.

Moths' eyes are covered with tiny structures that prevent them reflecting light and alerting night-time hunters looking for a meal. They also help the insects see in the dark. 

Scientists have copied the moth nanotechnology to produce an anti-reflective film that allows words and images to show up clearly on mobile devices even in bright sunlight.

A moth
A moth Credit: Visuals Unlimited/Corbis

The film reflects just 0.23% of the light falling on it, far less than the 4.4% reflected from the surface of an iPhone.

Strong light bouncing off a screen washes out the display, making it necessary to run for shade to check your emails.

US lead researcher Dr Shin-Tson Wu, from the College of Optics and Photonics at the University of Central Florida, said: "Using our flexible anti-reflection film on smartphones and tablets will make the screen bright and sharp, even when viewed outside.

"In addition to exhibiting low reflection, our nature-inspired film is also scratch resistant and self-cleaning, which would protect touch screens from dust and fingerprints."

The technology is described in latest issue of the journal Optica.

To get round the reflection problem, many smartphones use a sensor to detect bright ambient light and boost screen brightness.

While this improves readability, it also drains battery power.

Looking for a better solution, the researchers sought lessons from nature. Mimicking the moth eye, the new film contains tiny dimples, each 100 nanometres across - about 1,000th the width of a human hair - which cut down reflection.

A self-assembly technique developed by the scientists was used to produce the nanospheres with the required high level of precision.

Co-author Guanjan Tan, another member of the Florida team, said: "Although it is known that moth-eye structures can reduce surface reflection, it is relatively difficult to fabricate an anti-reflection film with this nanostructure that is large enough to use on a mobile phone or tablet.

"Because the structures are so small, a high-resolution and high-precision fabrication technique is necessary."

Tests showed that viewed in sunlight, glass covered with the film exhibited a more than four-fold improvement in "contrast ratio" - the different between the brightest white and darkest black.

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