Scientists at Nanyang Technological University in Singapore (NTU) and Tsinghua University have developed a stretchable and waterproof ‘fabric’ that turns energy generated from body movements into electrical energy. The fabric contains 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.
The team showed that tapping on a 3cm by 4cm piece of the new fabric generated enough electrical energy to light up 100 LEDs. The fabric can withstand washing, folding and crumpling without 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.
The electricity-generating fabric developed by the team is an energy harvesting device that turns vibrations produced from the smallest body movements in everyday
life into electricity.
The prototype fabric produces electricity in two ways: when it is pressed or squashed (piezoelectricity), and when it comes into contact or is in friction with other materials, such as skin or rubber gloves (triboelectric effect).
To fabricate the prototype, the scientists first made a stretchable electrode by screen-printing an ‘ink’ comprising silver and styrene-ethylene-butylene-styrene (SEBS), a
rubber-like material found in teethers and handlebar grips to make it more stretchable and waterproof. This stretchable electrode is then attached to a piece of nanofiber fabric that is made up of two main components: poly(vinylidene fluoride)-co-hexafluoropropylene (PVDFHPF), a polymer that produces an electrical charge when compressed, bent, or stretched; and lead-free perovskites.
NTU PhD student Jiang Feng, who is part of the research team, explained: “Embedding perovskites in PVDF-HPF increases the prototype’s electrical output. In our study, we opted for lead-free perovskites as a more environmentally friendly option. While perovskites are brittle by nature, integrating them into PVDF-HPF gives the perovskites exceptional mechanical durability and flexibility. The PVDF-HPF also acts an extra layer of protection to the perovskites, adding to its mechanical property and
stability.”
The result is a prototype fabric that generates 2.34 watts per square meter of electricity – enough to power small electronic devices, such as LEDs and commercial capacitors.
NTU professor, Lee Pooi See, 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.”
