Washable, breathable and stretchable cloths developed at Purdue University are paving the way for battery-free clothes powered by Wi-Fi.
First there were smart devices, now comes cloths that will make clothes smart. Engineers from Purdue University have developed a method to transform pieces of cloth into battery-free wearables that won’t break down in the laundry.
The commercial development of smart garments is currently hindered by significant challenges, such as dependence on batteries, reduced washability and difficult incorporation into existing large-scale textile manufacturing technologies.
The cloths the Purdue engineers have developed are powered wirelessly through a flexible, silk-based coil sewn on the textile, the university said. This will pave the way for clothes to become smart.
With miniaturized electronic circuits and sensors, these smart cloths will outperform conventional passive garments and will allow a wearer to seamlessly communicate with their phone, computer, car and other machines, according to the university.
“This smart clothing will not only make you more productive but also check on your health status and even call for help if you suffer an accident,” the university said.
One issue that has hindered the widespread deployment of smart clothing is that the fabrication of smart clothing “is quite challenging, as clothes need to be periodically washed–and electronics despise water,” according to Purdue.
However, “by spray-coating smart clothes with highly hydrophobic molecules, we are able to render them repellent to water, oil and mud,” said Ramses Martinez, an assistant engineering professor at Purdue, in a statement. “These smart clothes are almost impossible to stain and can be used underwater and washed in conventional washing machines without damaging the electronic components sewn on their surface.”
The rigidity of typical waterproof garments and their reduced breathability make them uncomfortable to wear after a few hours, he said.
“Thanks to their ultrathin coating, our smart clothes remain as flexible, stretchable and breathable as conventional cotton T-shirts,” Martinez said.
Unlike common wearables, the Purdue smart clothes do not require batteries for powering. By simply harvesting energy from Wi-Fi or radio waves in the environment, the clothes are capable of powering the circuitry sewn on the textile, he said.
For example, a battery-free glove that illuminates its fingertips every time the user is near a live cable warns about the possibility of an electric shock. Another example is a miniaturized cardiac monitoring system sewn on a washable sweatband capable of monitoring the health status of the wearer, according to Martinez.
“Such wearable devices, powered by ubiquitous Wi-Fi signals, will make us not only think of clothing as just a garment that keeps us warm but also as wearable tools designed to help us in our daily life, monitor our health and protect us from accidents,” Martinez said.
Eventually, he said he envisions smart clothes being able to transmit information about the wearer’s posture and motion to mobile apps, allowing machines to understand human intent without the need for other interfaces. This will expand “the way we communicate, interact with devices, and play video games.”
How it works
The engineers are using conventional fabrics and wirelessly powering them with omniphobic silk-based coils. OSCs are stretchable and lightweight power-receiving coils that can be easily sewn onto any textile, enabling the safe wireless powering of wearable electronics via magnetic resonance coupling, without compromising the comfort of the user, according to Purdue.
OSCs are composed of microfibers made of a novel silk-nanocarbon composite that benefits from the stretchability of silk fibroin and the high conductivity of multiwall carbon nanotubes and chitin carbon nanoflakes, the university said.
“OSC-powered e-textiles can be fabricated at a low cost using scalable manufacturing processes, paving the way toward the rapid development and commercialization of machine-washable and battery-free smart clothing and reusable wearable electrophysiological devices,” Purdue said.
The innovations are patent pending.