Soon, the “battery” powering your watch or fitness tracker could be your body. University of Colorado Boulder researchers invented a low-cost wearable apparatus that turns the human body into a biological battery.
You can wear this stretchy device like a bracelet, a ring, or any accessory that touches your skin. It will generate unlimited power, so long as you keep it on.
Study senior author Jianliang Xiao, an associate professor at CU Boulder, said:
In the future, we want to be able to power your wearable electronics without having to include a battery.
It works by using your body heat. Thermoelectric generators convert your internal temperature into electricity.
Usually, your body heat radiates out and is lost to the air. Xiao’s device captures that flow of energy, so it doesn’t go to waste.
He said:
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.
The device can generate approximately one volt of energy per square centimeter of skin. Most existing batteries provide more voltage per area, but it’s enough to power small wearable electronics, and it’ll never need to be replaced.
Xiao said:
Whenever you use a battery, you’re depleting that battery and will, eventually, need to replace it. The nice thing about our thermoelectric device is that you can wear it, and it provides you with constant power.
Thermoelectric devices to harness body heat aren’t new. However, Xiao’s is unique because it can heal itself when damaged.
Plus, it’s fully recyclable, so it’s an eco-friendly alternative to traditional electronics. When it reaches the end of its lifecycle, it can be submerged in a solution that dissolves the polyimine base, leaving the electronic components undamaged to be separated and reused. The dissolved polyimine can also be reused.
Xiao said:
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 and his colleagues have been working on projects focused on melding humans with robots for a while now. Their previous experiment involved designing “electronic skin” – wearable devices that behave and look like natural human skin. However, that android epidermis had to be linked to an external power source to function. The new invention changes everything – no external power source is needed because the human body is the power source!
The stretchy material (polyimine) – used for the electronic skin and the thermoelectric generator – is as resilient as biological tissue. If the device tears, all you have to do is pinch the broken ends together, and they’ll seal back up within minutes.
The team’s latest innovation consists of a base made of polyimine with a series of thin thermoelectric chips stuck into it and connected with liquid metal wires.
Xiao said:
Our design makes the whole system stretchable without introducing much strain to the thermoelectric material, which can be really brittle.
He notes that the design is scalable. To boost a device’s power output all, you’d have to do is add more blocks of generators – like Legos.
He said:
What I can do is combine these smaller units to get a bigger unit. 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.
A ring size device might only generate one volt of electricity, but a bracelet could yield much more. The team calculated that a person taking a brisk walk wearing a sports wristband-sized device could generate approximately five volts of electricity. That’s more than most watch batteries can muster.
Xiao said there are still kinks in the design to work out, but he expects the device to be market-ready within five to ten years.
Similar projects include a tattoo that turns your body into a touchpad by Saarland University researchers and technology that allows wearable devices to be powered by sweat instead of batteries by University of Glasgow researchers.
