Scientists develop ultra-thin battery for smart contact lenses that could possibly be charged by tears

The super-thin battery that could power smart contact lenses

Scientist Lee Seok Woo said a scene from the movie “Mission Impossible” inspired his latest invention: batteries for smart contact lenses.

In the fourth film within the series, an agent wears contact lenses that enable facial recognition and eye tracking. Lee desired to make this lens a reality.

“I asked myself, 'How can I work in the field of smart contact lenses?'” the associate professor within the Department of Electrical and Electronic Engineering at Nanyang Technological University told CNBC's “The Edge.”

Lee's expertise in battery components served as a start line for his foray into wearable technology. He realized that smart contact lenses would require secure and compact batteries, which can be critical to the continued development of those devices.

Contact lenses themselves are extremely thin at 0.5mm, so the dimensions and adaptability of those batteries are crucial to avoid discomfort for the user.

“The thickness of our battery is about 0.2 mm, which is about twice the thickness of a human hair,” Lee said.

Lee and his team have invented a battery that will be powered by a biocompatible saline solution as an alternative choice to lithium-ion batteries that contain flammable materials.

This recent battery will be charged using a standard wire method or a chemical method. The battery is coated with glucose and when immersed in a salt solution, the glucose reacts with the sodium and chloride ions and charges it.

After eight hours of chemical charging, the battery can reach 80% of its full capability. It can then be used for several hours through the day.

However, there’s one other unusual technique to power the battery.

“Tear solution also contains glucose, which means your tears can charge the battery even while you're wearing the contact lens,” Lee said.

“If you cry more, you can recharge your battery more.”

Currently, the capability and voltage of the battery are still very low. Using the 2 methods, the battery can only produce a voltage of about 0.3V – 0.6V. The standard voltage for an AA battery is 1.5V.

At this point, this power just isn’t enough to power data storage or a web connection, however the team is working on developing battery specifications.

Lee has identified a possible partner within the healthcare sector.

“We use glucose as biofuel. There are many diabetics who check their glucose levels daily,” Lee said.

“We investigated how we could measure glucose levels while the user is wearing the contact lens.”

Despite the potential promise of such innovation, Lee believes costs ought to be kept low given the capability of the batteries.

“Once the product is in serious commercial use, the cost of the battery should be only a few dollars.”

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