Tear-Based Battery Embedded with Prussian Blue Analogues and Silver Nanoparticles for Smart Contact Lenses

Smart contact lenses coupled with electronic components have vast potential for healthcare applications, as such advanced technology enables continuous and noninvasive monitoring of vital signs and disease diagnosis. However, stringent safety and nontoxicity requirements for ocular devices restrict the applications of flexible batteries fabricated by conventional methods. Here, we design a safe and flexible tear-based aqueous battery composed of Prussian blue analogues and silver nanoparticle films for cathode and anode, respectively. The battery exhibited satisfying cyclic electrochemical performance, with a discharge capacity of 195.37 μAh in a tear-like solution with interferences at 34.5 °C within the voltage ranges from 0.2 to 1.0 V. The power and voltage were sufficient to enable a temperature sensor. In addition, the rate capability, mechanical stability, and biocompatibility of the battery have been demonstrated as well.