The new battery is a nano-composite paper made by growing carbon nanotubes on a silicon substrate and impregnating the gaps between the tubes with cellulose, which is essentially paper.
The carbon nanotubes act as electrodes allowing the device to conduct electricity while maintaining its flexibility. The cellulose means that it can be activated by the natural electrolytes found in bodily fluids like blood and sweat.
The design allows the battery to maintain its integrity despite being bent, folded or even cut into pieces.
Ian Williams, Boffins patent paper battery