The device, described in the journal Science Advances, is stretchy enough that you can wear it like a ring, a bracelet or any other accessory that touches your skin. It also taps into a person’s natural heat—employing thermoelectric generators to convert the body’s internal temperature into electricity. 

This devices can generate about 1 volt of energy for every square centimeter of skin space—less voltage per area than what most existing batteries provide but still enough to power electronics like watches or fitness trackers.

Scientists have previously experimented with similar thermoelectric wearable devices, but this time, the wearable  is stretchy, can heal itself when damaged and is fully recyclable—making it a cleaner alternative to traditional electronics.

Until now, the latest innovation begins with a base made out of a stretchy material called polyimine. The scientists then stick a series of thin thermoelectric chips into that base, connecting them all with liquid metal wires. The final product looks like a cross between a plastic bracelet and a miniature computer motherboard or maybe a techy diamond ring. 

Just pretend that you’re out for a jog. As you exercise, your body heats up, and that heat will radiate out to the cool air around you. This device captures that flow of energy rather than letting it go to waste.

According to SciTech Daily