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First isolated in 2004, graphene has become one of the world’s most notorious nanomaterials to scientists and non-scientists alike. The use of graphene is continuing to grow with new applications emerging all the time, including in smart contact lens coatings.
Graphene is arguably one of the most versatile materials being used today as it possesses a large number of beneficial properties, many of which can be utilized simultaneously. There are also a number of different graphene forms available, which make it a plausible material for a number of applications.
Finally, there is a lot of interest in using graphene by scientists and end-user companies, meaning that more graphene products and applications are currently being developed than any other material.
Using Graphene in Coatings
One of the more common and longstanding applications of graphene is coatings. Graphene is useful in this application because it is possible to add a small amount of graphene into a coating medium to get added benefits. At the time when graphene was more expensive, this was a way to use graphene at a reduced cost. Graphene can also be used as a single-layer nanocoating without being immersed in a medium.
Over the years, different coatings have been devised using single-layer graphene, graphene nanoplatelets, and graphene oxide materials. Most coatings have focused around providing barrier properties that protect against different stimuli. Such coatings utilize the high stability of graphene in many areas such as ship hulls.
There have also been a number of electrically conductive and thermally conductive (or thermally dissipating) coatings for electronics and textiles, respectively, which utilize the highly conductive properties of graphene.
Another use is in optical coatings, which utilize the optical transparency of single-layered graphene sheets for a number of electronic-based applications.
Graphene-Based Smart Lenses
New graphene coating applications are always emerging, including in smart lenses. There are not that many areas where graphene is used within the medical field, but it is slowly growing as researchers find new and innovative ways to use and integrate graphene so that it poses no health risk to the user.
The use of graphene in smart contact lenses first started with implementing graphene sensors into contact lenses. As it is very thin, it has a very active surface area that is ideal for sensing (alongside its electrical conductivity for active detection). Such sensors have been implemented into contact lenses to detect infrared light waves, which, in turn, could enable the user to see better in the dark, acting as night-vision contact lenses.
Graphene as a conductive coating in contact lenses
Research over the last few years has investigated other areas in which graphene could be used within contact lenses, namely as a conductive coating. Among the many different properties it possesses, graphene has electromagnetic interference shielding (EMI) properties, which help to protect the eyes against electromagnetic waves, reducing the chance of cataracts occurring. Given graphene’s flexibility and high tensile strength, it can be implemented on complex and curved surfaces, such as those found on the eyeball, and the contact lenses that sit above the eye.
Preventing eye dehydration using graphene-coated contact lenses
As well as to protect against electromagnetic waves, these contact lenses have also been used to prevent the dehydration that contact lenses often cause by keeping in moisture from tear fluid.
The contact lenses were rigorously tested using egg whites as model eyeballs, and they were subjected to an extensive amount of microwave radiation. The tests found that the graphene coating absorbed a lot of the microwaves and dissipated it in the form of thermal radiation. This minimized the damage to the egg white underneath the contact lens. It was found that such properties of the graphene coating persisted in wet environments and the coatings had good biocompatibility, making them suitable for human use.
The Future of Graphene Coatings in Smart Lenses
While such contact lenses are not available to the general public and are still in the infancy of development, graphene coatings in smart contact lenses offer a way of protecting users’ eyes in the future. As well as being used for humans, it is thought that such smart contact lenses could also be used within display and sensor applications.
Click here for more information on equipment used to study graphene properties
References and Further Reading
The Gadgeteer: https://the-gadgeteer.com/2020/02/28/are-smart-contact-lenses-going-to-be-the-next-big-wearable-of-the-future/
“Smart Contact Lenses with Graphene Coating for Electromagnetic Interference Shielding and Dehydration Protection”- Hong B. H. et al, ACS Nano, DOI: 10.1021/acsnano.7b00370
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