Devices, Research, Technology

New smart contact lens design solves hydration problem

A new smart contact lens design capable of preventing dry eye has the potential to solve a significant problem associated with the emerging technology.

The design from Tohoku University promises to make wearing so-called smart contact lenses, which companies and research institutions are currently racing to develop for a variety of applications, for longer periods of time possible.

“Although there have been many recent advancements in new functions for smart contact lenses, there has been little progress in solving the drawbacks associated with wearing contact lenses day to day,” Professor Matsuhiko Nishizawa, engineer at Tohoku University, said.

According to the team behind the project, a system based on electroosmotic flow (EOF) is capable of keeping the eye sufficiently moistened. EOF is the phenomenon that causes liquid to flow across a charged surface when voltage is applied.

In the novel mechanism described by the researchers, an electrical current applied to a hydrogel lens causes fluid from the wearer’s temporary tear reservoir behind the lower eyelid to flow up and over the eye’s surface. This keeps a layer of fluid between the contact lens and eye, avoiding the symptoms of dry eye syndrome that typically accompanies prolonged contact lens wear.

“This is the first demonstration that EOF in a soft contact lens can keep the lens moist,” Nishizawa said.

As with many smart contact lens prototypes, power and batteries continue to be a challenge. The researchers behind the project tested two types of batteries known to be safe and non-toxic: a magnesium-oxygen battery and an enzymatic fructose-oxygen fuel cell. Both biobatteries were successful at powering the device, and also capable of being mounted directly on the charged contact lens.

The team now plans to work on expanding this technology to further applications, as well as developing contact lenses that are tougher and able to operate at smaller currents.

A paper detailing the technology was in the journal Advanced Materials Technologies.

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