Self-Moisturizing Smart Contact Lens Employing Electroosmosis

Contact lenses (CLs) can be a cause of dry eye syndrome that can lead to corneal wounds and inflammation as well as a feeling of discomfort. To prevent the dry eye, it is important to keep the lens moist and maintain tears between the CL and the ocular surface. Here, the use of electroosmotic flow (EOF) in a CL is reported as a novel mechanism for antidehydration. A CL made from a charged hydrogel has served as the fluid conduit for EOF generation. The charge density of the gel is optimized by varying the composition ratio of anionic monomer having carboxyl group, by taking into account the efficiency of EOF generation and the mechanical strength of the hydrogels. By in situ monitoring of conductance and by microscope observations, it is successfully demonstrated that the upward EOF within CL is effective to maintain a moist lens. Biocompatible batteries (Mg/O-2 battery and fructose/O-2 enzymatic battery) are mounted on the CL to demonstrate the feasibility of a smart CL with a built-in power source for EOF-based self-moisturization.