Power supply for a smart contact lens

Abstract

Smart contact lenses with IoT have vast potential in healthcare, sports, and augmented reality, as they evolve with advanced sensors and electronic components. Yet, developing a dependable, compact, biocompatible, long-lasting high energy density power source remains a significant challenge due to the limited space in contact lenses to meet the energy demands of electronic components. Herein, a safe and flexible aqueous battery that operates in tears was fabricated, and the performance were analysed.

Silver (Ag) and Copper Hexacyanoferrate (CuHCFe) were chosen as battery’s anode and cathode were embedded in hydrogel that was UV-polymerized as soft contact lens with lens cleansing tissue in between that acted as ion-permeable separator. The battery was subject to cyclic voltammetry (CV) and galvanostatic cycling with potential limitation (GCPL) electrochemical test in 1M of NaCl to simulate tear fluid environment.

The battery revealed a high coulombic efficiency of 99.3% and specific capacity 46.52 mAh/g. It also exhibits potential of 0.9V and 0.143mA that is adequate for powering a small static random-access memory (SRAM) that can be incorporated into the contact lens. In addition, a test was conducted to assess the viability of using a booster converter to power the Bluetooth module with the battery as the power source, to establish a Bluetooth connection.