
Self-healing and eco-friendly devices that generate electricity from body heat could power wearable gadgets, such as a heart monitor for runners.
Jianliang Xiao at the University of Colorado, Boulder, and his colleagues created devices based on thermoelectric generators, which convert heat into electricity. The team embedded a number of these generators in a thin film made from a flexible polymer called polyimine and wired them together with a liquid gallium-indium alloy to create stretchable bands that can be worn on arms, legs and fingers. The device costs less than $10 to produce.
The team tested a wrist-worn version of the device by asking someone to wear it while both sitting and walking. The increased body heat during walking generated enough power – 12.5 microwatts – to power small sensors such as a heart monitor or motion tracker, says the team.
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The liquid metal and polyimine make the device self-healing – the team could cut it then place the two halves next to each other, and within a couple of hours it would repair with no hit to performance. “This would extend the life of the devices,” says Xiao.
This also means the device is easy to recycle. Xiao’s team soaked one in an alcohol-based solution to break down the polyimine, freeing the generators and liquid metal. The group then created a new polyimine film from the solution and recombined it with the components from the old device to create a new one with comparable performance. “This can lead to mass production of recycled electronics and reduce electronic waste from wearable devices,” says Xiao.
Science Advances