A contact lens with integrated micro solar cells

We report the design, construction, characterization and in vivo testing of contact lenses incorporating solar cells. A fabrication process is outlined yielding free-standing 500 × 500 × 10 μm³ single crystal silicon solar cells which are subsequently integrated into a contact lens. Collections of micrometer-scale solar cells are interconnected on the contact lens in order to maintain flexibility, cover the proper area, and take advantage of crystalline materials. The solar cells show maximum efficiency at wavelength 725 nm with conversion efficiency of 1.24% at 310 mV. The contact lenses were tested on live rabbits and no adverse effects were detected. Contact lenses equipped with solar cells can harvest usable power from the environment and pave the way for the deployment of stand-alone contact lens systems that can be used for health-status monitoring.