Move over spy movies, smart contact lenses are no longer just a fictional concept. In fact, researchers have been hard at work developing these lenses for various purposes, such as monitoring glucose levels, detecting cancer, and even capturing photos with our eyes, just like in an episode of Black Mirror.
However, one major hurdle in their development has been finding a safe and convenient way to power them. Traditional batteries with metal wires are not suitable for the delicate eye. But fear not, researchers at Nanyang Technological University Singapore have found inspiration in the eye itself to create a biocompatible solution.
“This research began with a simple question,” said lead author Lee Seok Woo. “Could contact lens batteries be recharged with our tears? There were similar examples for self-charging batteries, such as those for wearable technology that are powered by human perspiration.”
The team successfully developed a bio-safe battery that is as thin as the human cornea. By using tears as their inspiration, they coated the battery with an enzyme called glucose oxidase, which reacts with the sodium and chloride ions found in tears. This reaction, known as reduction, generates electricity. The battery also contains water, acting as “circuitry” for the electricity.
“It relies on just glucose and water to generate electricity,” explained Woo. “Both of which are safe for humans and less harmful to the environment when disposed of, compared to conventional batteries.”
To test its functionality, the researchers placed the battery in a simulated eye and used saline solution to mimic tears. It successfully powered up, producing a current of 45 microamperes and a maximum power of 201 microwatts. They also discovered that it could discharge power up to 200 times, only around 100 times less than a typical lithium-ion battery.
With a starting point that already powers a smart contact lens, the team plans to further improve the battery’s electrical current in future research.
So, keep your eyes peeled for more exciting developments in smart contact lens technology.
The study is published in the journal Nano Energy.
