Contact lens biofuel cell tested in a synthetic tear solution

A contact lens biofuel cell was fabricated using buckypaper electrodes cured on a silicone elastomer soft contact lens. The buckypaper anode consisted of poly(methylene green) and a hydrogel matrix containing lactate dehydrogenase and nicotinamide adenine dinucleotide hydrate (NAD+). The buckypaper cathode was modified with 1-pyrenemethyl anthracene-2-carboxylate, and then bilirubin oxidase was immobilized within a polymer. Contact lens biofuel cell testing was performed in a synthetic tear solution at 35 °C. The open circuit voltage was 0.413±0.06 V and the maximum current and power density were 61.3±2.9 µA cm−2 and 8.01±1.4 µW cm−2, respectively. Continuous operation for 17 h revealed anode instability as output current rapidly decreased in the first 4 h and then stabilized for the next 13 h. The contact lens biofuel cell presented here is a step toward achieving self-powered electronic contact lenses and ocular devices with an integrated power source.