Colorado researchers create wearable device that turns the body into a battery

An innovative wearable device that “transforms the human body into a biological battery” has been invented by researchers at the University of Colorado Boulder. By using a series of thin thermoelectric generators, the device converts internal body heat into electricity. The polyimine base makes for a lightweight, stretchy device that can be worn like a ring or bracelet. It’s also able to fix itself after damage and is fully recyclable —  making the device a greener alternative to traditional electronics.

A high-tech accessory

When you go out running, for example, your body temperature increases and heat flows out into the surrounding air. Rather than allow that heat to dissipate, it’s captured by the device. “The thermoelectric generators are in close contact with the human body, and they can use the heat that would normally be dissipated into the environment,” said Jianliang Xiao, lead researcher and associate professor in the Paul M. Rady Department of Mechanical Engineering at CU Boulder. The device generates around 1 volt of energy per square centimeter of skin — not as much as most typical batteries, but able to power devices like watches, health monitors, and fitness trackers. “Whenever you use a battery, you’re depleting that battery and will, eventually, need to replace it,” Xiao said. “The nice thing about our thermoelectric device is that you can wear it, and it provides you with constant power. In the future, we want to be able to power your wearable electronics without having to include a battery”.

Extra power

However, extra thermoelectric chips can be simply added to the device to enhance its power. “What I can do is combine these smaller units to get a bigger unit,” Xiao said. “It’s like putting together a bunch of small Lego pieces to make a large structure. It gives you a lot of options for customization.” So, a person wearing the device the size of a standard sports wristband could generate about five volts of electricity on a brisk walk — much more than most watch batteries. Moreover, performance-enhancing agents can also be used to help people get the most out of exercise; however, more research is needed in this area.

Resilient design

The device is also designed to be as durable as biological tissue. For instance, a tear can be simply pinched together and the ends will seal within a couple of minutes. And, if you submerge the device in a special solution, the polyimine base will completely dissolve while the thermoelectric chips separate, so they can be reused.
“We’re trying to make our devices as cheap and reliable as possible, while also having as close to zero impact on the environment as possible,” Xiao said. Although the design is yet to be finalized, Xiao hopes it will launch on the market within the next five to ten years.