Stretchable biofuel cells use sweat to power wearable devices

The epidermal biofuel cells, which are claimed to generate 10 times more power per surface area than any existing wearable biofuel cells, are a major breakthrough in the field, which has been struggling to make devices that are stretchable enough and powerful enough.

Engineers from the University of California San Diego were able to achieve this breakthrough thanks to a combination of chemistry, advanced materials and electronic interfaces. This allowed them to build a stretchable electronic foundation by using lithography and by using screen-printing to make 3D carbon nanotube-based cathode and anode arrays.

The biofuel cells are equipped with an enzyme that oxidises the lactic acid present in human sweat to generate current. This turns the sweat into a source of power.

The engineers report their results in Energy & Environmental Science. In the paper, they describe how they connected the biofuel cells to a custom-made circuit board and demonstrated that it was able to power an LED while a person wearing it exercised on a stationary bike.