A casein-based biodegradable and sustainable capacitive sensor

The production of electrical and electronic equipment is increasing worldwide with a dramatic increase of electronic waste. Sustainable materials to produce sensors may thus positively impact on the environment. Casein is a milk protein that was used to fabricate a non-cytotoxic and biodegradable capacitive sensor by a green chemical process adding glycerol and trehalose. The casein-based film was characterized by means of thermal (TGA and EGA-MS) and spectroscopic (FTIR-ATR and Dielectric Spectroscopy) techniques. Contact angle, water vapour transmission rate, cytotoxicity and biodegradability were also assessed. A PEDOT:PSS/reduced graphene oxide ink was produced and screen-printed onto the film surface to obtain electrically conductive electrodes. The dielectric properties of the casein-based film allowed for the fabrication of a capacitive sensor that proved sensitive to pH changes.