NTU Singapore scientists have developed paper-thin biodegradable zinc batteries that could one day become an environmentally sustainable option for powering flexible and wearable electronic systems. These zinc batteries are made up of electrodes (through which the electrical current leaves or enters the battery) screenprinted on to both sides of a piece of cellulose paper that has been reinforced with hydrogel. Once the battery has been expended, it can be buried in soil, where it breaks down ...