Electrochromic soft contact lenses with built-in non-interfering, high-efficient dual-band wireless power transfer system

Color contact lenses attracts considerable attention for vision management and cosmetic applications nowadays. However, they require a wired power supply system because positive and negative voltages need to be applied for color modulation of electrochromic coating on the lens. This study demonstrates a wireless-powered electrochromic soft contact lens that modulates color using a dual-band wireless power transfer (WPT) system. The stretchable and conductive electrochromic film is the result of fabrication by spin-coating a mixed solution comprising PEDOT:PSS for the electrical conductor, polyurethane for the stretchable supportive layer, ethylene glycol, and dodecylbenzene sulfonic acid as conductivity enhancers. The dual-band system for negative voltage at 13.56 MHz and positive voltage at 28.4 MHz consists of two resonators using semi-loop antennas connected in parallel with capacitors. The dual-band resonators and electrochromic films are electrochemically bonded onto a commercially available soft contact lens. The proposed lens is capable of reversibly and wirelessly modulating the color from transparent to dark blue for several tens of seconds and usable as wireless color filters and Morse code transmitters.