The wearable device turns the touch of a finger into a source of power for small electronics and sensors. It can be used in any daily activity involving touch; for example, things a person would normally do while at work, at home, while watching TV, or eating.
A thin, flexible strip can be worn on a fingertip to generate small amounts of electricity when a person’s finger sweats or presses on it. It generates power even while the wearer is asleep or sitting still, requiring no exercise or physical input. The wearable energy harvester generates extra power from light finger presses — activities such as typing, texting, or playing the piano become sources of energy. A padding of carbon foam electrodes absorbs sweat and converts it into electrical energy. The electrodes are equipped with enzymes that trigger chemical reactions between lactate and oxygen molecules in sweat to generate electricity. Underneath the electrodes is a chip made of piezoelectric material that generates additional electrical energy when pressed. As the wearer sweats or presses on the strip, the electrical energy gets stored in a small capacitor and is discharged to other devices when needed.
University of California, San Diego
The wrap could serve as a power source anytime, anywhere, without the limitations of solar cells, which only work under sunlight, or thermoelectric generators, which only work when there’s a large temperature difference between the device and the surroundings. From 10 hours of sleep, the device collected almost 400 millijoules of energy — enough to power an electronic wristwatch for 24 hours. Putting the wraps on all ten fingertips would generate 10 times more energy.
The team is making further improvements to the device so that it is more efficient and durable. Future studies will include combining it with other types of energy harvesters to create a new generation of self-powered wearable systems.