A biofilm that sticks to the skin like a Band-Aid to harness sweat for electricity that could power wearable devices. The biofilm is made using a bacteria that converts energy from evaporation into electricity, making use of the moisture on a person's skin as it turns into vapour.

According to the researchers, evaporation is a "huge, untapped source of energy".

In its current form the biofilm produces enough energy to power small devices such as medical sensors or personal electronics, but the team also plans to explore larger films that can power even more sophisticated devices. At an even larger scale, they hope the biofilm could be used to make more use of the untapped energy from evaporation, pointing to research that shows around 50 per cent of the solar energy reaching earth is spent on the process.