A prototype smart textile is now capable of harvesting biomechanical energy to self-power wearables through body movement and more importantly is flexible, breathable with excellent water resistance and air permeability to provide comfort and convenience in practical application.
Proof-of-concept: In a proof-of-concept experiment reported in the scientific journal Advanced Materials, the scientists working on the project said that the prototype fabric generates 2.34 watts per square metre of electricity—enough to power small electronic devices, such as LEDs and commercial capacitors.
- A crucial component in the fabric is a polymer that, when pressed or squeezed, converts mechanical stress into electrical energy. It is also made with stretchable spandex as a base layer and integrated with a rubber-like material to keep it strong, flexible, and waterproof.
- Washing, folding, and crumpling the fabric did not cause any performance degradation, and it could maintain stable electrical output for up to five months, demonstrating its potential for use as a smart textile and wearable power source.
Harvesting an alternative source of energy: A team from the Technological University (NTU) Singapore led by Materials scientist and NTU Associate Provost (Graduate Education) Professor Lee Pooi See said experiments on a 3cm by 4cm piece of a new polymer fabric generated enough electrical energy to light up 100 LEDs, and that crumpling, folding or washing did not degrade the performance. Besides, it could maintain stable electrical output for up to five months. This work provides a practical strategy to design multifunctional self-powered wearable electronic devices.
“There have been many attempts to develop fabric or garments that can harvest energy from movement, but a big challenge has been to develop something that does not degrade in function after being washed, and at the same time retains excellent electrical output. In our study, we demonstrated that our prototype continues to function well after washing and crumpling. We think it could be woven into t-shirts or integrated into soles of shoes to collect energy from the body’s smallest movements, piping electricity to mobile devices,” he said.
The prototype fabric generates electricity when it is pressed or squashed (piezoelectricity), and when it comes into contact or is in friction with other materials, like skin or rubber gloves (triboelectric effect).
Harnessing energy: To demonstrate how their prototype fabric could work, the NTU scientists showed how a hand tapping on a 3cm by 4cm piece of the fabric continuously could light up 100 LEDs, or charge several capacitors. The electricity-generating fabric thus is an energy harvesting device that turns vibrations produced from the smallest body movements in everyday life into electricity.
- The scientists showed that their fabric could harness energy from a range of human movements by attaching it to the arm, leg, hand, and elbow, as well as to the insoles of shoes, and did so without impacting on the movements.
- This fabric-based energy harvesting prototype builds on the NTU team’s body of work that looks at how energy generated in the environment could be scavenged. For instance, the team recently developed a type of film that could potentially be mounted on roofs or walls to harness the energy produced from wind or raindrops falling onto the film.
The team is now looking at how the same fabric could be adapted to harvest different forms of energy.
What they said:
Despite improved battery capacity and reduced power demand, power sources for wearable devices still require frequent battery replacements. Our results show that our energy harvesting prototype fabric can harness vibration energy from a human to potentially extend the lifetime of a battery or even to build self-powered systems. To our knowledge, this is the first hybrid perovskite-based energy device that is stable, stretchable, breathable, waterproof, and at the same time capable of delivering outstanding electrical output performance.
— Lee Pooi See
Materials scientist and NTU Associate Provost
Nanyang Technological University
