Novel material gives nod to 'invisibility cloak'

(Tania Zbrodko)

Physicists in Scotland said on Thursday they had devised a flexible material that manipulates light, marking a small step towards "invisibility" clothing beloved of science fiction writers and Harry Potter.

The work is in the domain of metamaterials, or compounds with a surface that interacts with light thanks to a tiny, nano-level structure.

As a result, light flows around the object - rather like water that bends around a rock in a stream - as opposed to being absorbed by it.

Metamaterials are still in the prototype stage and enact their apparent shielding effect in specific wavelengths, or colours, of the light spectrum.

They have traditionally been made from rigid substances, not flexible materials, and this is a limiter on their potential use.

The research team, led by Andrea di Falco of the University of St. Andrews, made the novel material using an elaborate technique based on a commercially available polymer and a silicon support.

The invention, dubbed Metaflex, interacts with light at wavelengths of around 620 nanometres, according to the research, published in Britain's New Journal of Physics.

Visible light, for humans, has wavelengths ranging from 400 nanometres, where the perceived colours are violet and purple, to 700 nanometres, which is deep red.

In a demonstration of the substance's flexibility, the scientists placed a layer of Metaflex onto ordinary contact lenses. Just a tiny amount of the substance has been made, in order to prove the theory that a flexible metamaterial can be made.

"Metamaterials give us the ultimate handle on manipulating the behaviour of light," Di Falco said.

Metaflex could have a wide use in optics as well as smart clothing, he added.

Previous work in flexible metamaterials has yielded success in the terahertz and near-infrared parts of the electromagnetic spectrum, but this is is not light that is visible to humans.