Organic electrochromic timer for enzymatic skin patches

Abstract A totally organic and disposable electrochromic timer integrated with an enzymatic electrode and powered by biofuel cells is developed. The cathode of the self-powered electrochromic timer consists of a composite electrochromic film of poly(3,4-ethylenedioxythiophene) (PEDOT) and polyurethane (PU), while the anode is made up of a fructose dehydrogenase (FDH) enzymatic electrode. The electrochromic changes over time (up to 100 min) can be displayed in the device, and the speed of color change can be controlled by changing the resistance between the anode and the cathode. Automatic activation of the timer after placement on a skin is achieved by integrating a porous microneedle array. The electrochromic timer would be used along with a skin patch as a time-lapse display of medical and cosmetic treatments.