A joint research project between scientists at the University of Adelaide and RMIT University has yielded a stretchable nano-scale device which can filter specific colours, while still being transparent.
This degree of light manipulation is possible because of tiny artificial crystals called "dielectric resonators", which measure just a fraction of the wavelength of light: at 100 to 200 nanometres, these crystals are over 500 times thinner than a human hair.
This technology could one day allow the engineering of high-tech lenses that can filter out harmful optical radiation without interfering with vision. As the technology advances, it may be possible to create smart contact lenses that are able to transmit data and gather live vital, or even show information like a head-up display.
The research combined the University of Adelaide researchers’ expertise in interaction of light with artificial materials with the materials science and nanofabrication expertise at RMIT University.
According to Dr Withawat Withayachumnankul, from the University of Adelaide’s School of Electrical and Electronic Engineering, manipulation of light using these artificial crystals required precise engineering.
"With advanced techniques to control the properties of surfaces, we can dynamically control their filter properties, which allow us to potentially create devices for high data-rate optical communication or smart contact lenses," he said.
"The current challenge is that dielectric resonators only work for specific colours, but with our flexible surface we can adjust the operation range simply by stretching it."
The devices were made on a rubber-like material, the same which is used for contact lenses. The researchers embedded precisely-controlled crystals of titanium oxide, which is a common ingredient in sunscreen, in the material.
Because both materials are bio-compatible, the resulting nano-scale devices are ideally suited as wearable optical devices.
By engineering the shape of these common materials, the researchers created a device that changes properties when stretched, modifying the way the light interacts with and travels through the device: stretching the material would changes its colours and light interactivity.
The research was also a breakthrough in materials engineering: a major scientific hurdle was combining high temperature processed titanium dioxide with the rubber-like material, and achieving nano-scale features.