Smart graphene contact lenses bring wearable electronics to the eye
(Nanowerk Spotlight) Several research projects are working on reinventing the contact lens as a smart electronic device that, for instance, works as a self-powered biosensor for various point-of-care monitoring and wireless biomedical sensing, which may detect in real time the pathogen, bacteria, glucose, and infectious keratitis present in tear fluid. One example is a recently developed sensor for diabetic and glaucoma diagnosis.
In addition to sensors, researchers are devising numerous applications for smart contact lenses, ranging from drug delivery systems to protection from electromagnetic wave damage.
Smart contact lens. Schematics of fully passive, transparent, and conformal all-graphene harmonic sensor designed for various point-of-care monitoring and wireless biomedical sensing. The right panel illustrates an eye-wearable device (smart contact lens) based on the all-graphene harmonic sensor, which may detect in real time the pathogen, bacteria, glucose, and infectious keratitis. (Image: Pai-Yen Chen's research group, Wayne State University) (click on image to enlarge)
An application closer to contact lenses' original function, graphene can change the focal length of a polymeric soft contact lens in order to adjust near- and farsightedness. That means a single contact lens could be multifocal because an active graphene membrane can change its curvature reversibly from flat to a concave or convex shape under an electrical bias.
Due to the mass impermeability of a pristine graphene lattice, graphene also can mitigate ocular dehydration.
An electromagnetic interference (EMI) shielding effect is a promising feature of graphene use in a smart contact lens. In order to facilitate data communication and power charge, a wireless antenna interacting with electromagnetic waves is likely essential for the smart lens; however, continuous exposure to electromagnetic waves may harm eyeballs by low-temperature burns or dehydration (in an experiment, researchers showed that that egg white underneath a normal soft contact lens was damaged in a microwave oven).
"In the future, smart contact lenses could be widely used to monitor and to diagnose diseases continuously," the authors conclude. "If equipped with actuator functions, they could also be adapted in therapeutics such as an ocular drug-delivery platforms. Furthermore, lenses equipped with a display application will be able to provide augmented reality as the on-demand information will be projected directly in the field of view."