IISc researchers develop tunable coloured films for displays and sensors

NT Correspondent

Bengaluru: Researchers at the Indian Institute of Science (IISc) have developed flexible films that exhibit bright colours purely by virtue of their physical structure, without the need for any pigment.

When stretched, the films exhibit a change in colour as a response to the mechanical deformation, the Bengaluru-based IISc said in a press release on Tuesday.

To design these films, the team devised a novel costeffective and scalable singlestep technique that involves evaporating gallium metal to form nano-sized particles on a flexible substrate.

Their method allows the simultaneous fabrication of multiple structural colours responsive to mechanical stimuli.

The team has also shown how these films can be used for a variety of applications, from smart bandages and movement sensors to reflective displays. the release said.

"This is the first time that a liquid metal like gallium has been used for photonics," says Tapajyoti Das Gupta, Assistant Professor in the Department of Instrumentation and Applied Physics (IAP), and corresponding author of the study published in 'Nature Nanotechnology.'

Some natural objects like gemstones, mollusk shells or peacock feathers are inherently colourful.

Their colours emerge from the interaction of light with micro- or nano-structures arranged periodically, such as tiny silica spheres in opal, calcium carbonate-based platelets in mollusc shells, and segmented ribbons atop cylindrical structures in peacock feathers.