‘Smart’ clothing could turn body movements into electricity that charges phones on the go

BATH, United Kingdom — Plenty of people have experienced that moment when they remember they haven’t charged their phone all day and now it’s out of power. A recent study reveals there could be a way to charge your smartphone just by walking to the store. Researchers at the University of Bath say clothing “smart” enough to turn gentle body movements into electricity could keep our phones charged while on the move, according to a new study.

Scientists say nylon fibers, which produce electricity from simple body movements known as “swirl power,” could be useful at powering sensors and mobile devices. The piezoelectric nylons generate a charge when touched which can then be harnessed and stored in a battery. Even the simplest movement, like swinging your arms, while wearing smart clothing would be enough to produce electricity.

“There’s growing demand for smart, electronic textiles, but finding cheap and readily available fibers of electronic materials that are suitable for modern-day garments is a challenge for the textile industry,” says study lead author Professor Kamal Asadi in a university release.

smart clothing
When woven into clothes, piezoelectric fibers will transform mechanical energy into electric energy every time a person moves. (Credit: Katharina Maisenbacher, Max Planck Institute)

“Piezoelectric materials make good candidates for energy harvesting from mechanical vibrations, such as body motion, but most of these materials are ceramic and contain lead, which is toxic and makes their integration in wearable electronics or clothes challenging,” Asadi adds.

The difficult road to making smart clothing

Scientists have known about nylon’s piezoelectric properties since the 1980’s. They were keen to experiment with it as it does not contain any toxic materials. However, the manmade fabric — common in cheap T-shirts and women’s stockings — is “very difficult” to handle. Nylon, in its raw form, is a white powder that can be blended with materials before being molded into products. It can make anything from car parts to toothbrush bristles.

The study finds that when nylon is turned into a “particular” crystal form, on the other hand, it becomes piezoelectric. For this to happen, it must be melted, rapidly cooled, and then stretched. This produces thick slabs, or films, which are piezoelectric but not suitable for making battery-charging clothes.

Most research in this area ground to a halt during the 1990’s as the challenge of producing thin piezoelectric nylon was thought to be insurmountable. Adopting a completely different approach, the researchers dissolved the nylon powder in acid rather than melting it. While it produced thinner nylon, the finished product contained solvent molecules which prevented it from becoming piezoelectric.

“The challenge is to prepare nylon fibers that retain their piezoelectric properties,” Prof. Asadi explains. “We needed to find a way to remove the acid to make the nylon useable.”

Creating the future of charging fabrics

The researchers mixed the acid solution with acetone, a chemical commonly connected to paint thinners or nail varnish removers. Study authors discovered a nylon piezoelectric film could then be produced by extracting the acid.

“The acetone bonds very strongly to the acid molecules, so when the acetone is evaporated from nylon solution, it takes the acid with it,” Asadi adds. “What you’re left with is nylon in its piezoelectric crystalline phase. The next step is to turn nylon into yarns and then integrate it into fabrics.”

The findings could pave the way towards electronic textiles and smart clothing, which could power wearable electronics and portable devices.

“The goal is to integrate electronic elements, such as sensors, in a fabric, and to generate power while we’re on the move,” the professor in Bath’s Department of Physics says. “Most likely, the electricity harvested from the fibers of piezoelectric clothing would be stored in a battery nestled in a pocket. This battery would then connect to a device either via a cable or wirelessly. In years to come, we could be using our T-shirts to power a device such as our mobile phone as we walk in the woods, or for monitoring our health.”

The findings appear in the journal Advanced Functional Materials.

SWNS writer Tom Campbell contributed to this report.

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