Sweat powered smartwatches:Engineers at the University of Glasgow have developed a new type of flexible supercapacitor, which stores energy, replacing the electrolytes found in conventional batteries with sweat.
It can be fully charged with as little as 20 microlitres of fluid and is robust enough to survive 4,000 cycles of the types of flexes and bends it might encounter in use.
The device works by coating polyester cellulose cloth in a thin layer of a polymer, which acts as the supercapacitor’s electrode.
As the cloth absorbs its wearer’s sweat, the positive and negative ions in the sweat interact with the polymer’s surface, creating an electrochemical reaction which generates energy.
"Conventional batteries are cheaper and more plentiful than ever before but they are often built using unsustainable materials which are harmful to the environment," says Professor Ravinder Dahiya, head of the Bendable Electronics and Sensing Technologies (Best) group, based at the University of Glasgow’s James Watt School of Engineering.
“That makes them challenging to dispose of safely and potentially harmful in wearable devices, where a broken battery could spill toxic fluids on to skin.
“What we’ve been able to do for the first time is show that human sweat provides a real opportunity to do away with those toxic materials entirely, with excellent charging and discharging performance.
