A wearable device was developed that taps into a person’s natural heat, employing thermoelectric generators to convert the body’s internal temperature into electricity. In the future, wearable electronics could be powered without having to include a battery.
The device 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.
The thermoelectric wearable device can heal itself when damaged and is fully recyclable, making it a cleaner alternative to traditional electronics. It consists of a base made out of a stretchy material called polyimine. The team then sticks 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. The design makes the system stretchable without introducing much strain to the thermoelectric material, which can be very brittle.
As the wearer exercises and the body heats up, the heat radiates out to the cool outside air. The wearable device captures that flow of energy rather than letting it go to waste. The team calculated that a person taking a brisk walk could use a device the size of a typical sports wristband to generate about 5 volts of electricity, which is more than what many watch batteries can muster.
The device is as resilient as biological tissue. If the device tears, for example, the broken ends can be pinched and they will seal back up in a few minutes. When done with the device, it can be dunked into a special solution that will separate out the electronic components and dissolve the polyimine base — each one of those ingredients can then be reused.