Researchers at Seoul National University, Graphene Square and Interojo have shown that graphene-coated contact lenses could protect eyes from electromagnetic radiation and dehydration and be used in various healthcare and wearable technologies. The researchers began by synthesising a graphene layer on a copper foil using CVD. They then transferred the carbon sheet onto the surface of a contact lens with the help of a polymer layer after etching the copper.
"Thanks to its outstanding flexibility, graphene can be coated on the convex lens surface and conform to it," explains the team. The team tested the EM wave-shielding properties of the coated lens by testing it out on egg whites exposed to strong EM waves inside a microwave oven. The results showed that the EM energy is absorbed by the graphene layer and dissipated as heat throughout it so that damage to the egg white is minimised.
"When the graphene is exposed to EM waves, the electrons in orbital motion induce oscillating magnetic moments in response to the external magnetic field, which efficiently absorbs the EM energy and disperses it as thermal energy," explain the researchers.
"We can thus evaluate the material's EM absorption efficiency by monitoring the heat produced in the graphene-coated contact lens. We did this by using an IR camera to obtain thermal infrared images after applying EM radiation (of 120 W) on the samples inside a microwave oven for 20 seconds and found that the temperature of the graphene-coated contact lens rapidly increased to more than 45°C, while a normal lens hardly increased in temperature."
The team believes that such a lens could make for a new healthcare platform for wearable technologies in the future. "For diabetes diagnosis, for example, we are now planning to integrate an active circuit with graphene-based sensors and electrodes for real-time wireless monitoring of glucose concentration in tears in collaboration with a contact lens company", said the team.