Purdue engineers have developed a new spray/sewing method to transform any conventional cloth items into battery-free wearables that can be cleaned in the washing machine. The researchers published their innovation in Nano Energy.

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"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 professor in Purdue's School of Industrial Engineering and in the Weldon School of Biomedical Engineering in Purdue's College of Engineering. "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 feel uncomfortable after being worn for a few hours, reports Purdue University.

"Thanks to their ultrathin coating, our smart clothes remain as flexible, stretchable, and breathable as conventional cotton T-shirts," Martinez said.

Unlike common wearables, 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.

One example is a battery-free glove that illuminates its fingertips every time the user is near a live cable to warn about the possibility of an electric shock. Another is a miniaturized cardiac monitoring system sewn on a washable sweatband capable of monitoring the health status of the wearer.

"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.

"I envision smart clothes will be able to transmit information about the posture and motion of the wearer to mobile apps, allowing machines to understand human intent without the need for other interfaces, expanding the way we communicate, interact with devices, and play video games."

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This technology can be fabricated in conventional, large-scale sewing facilities, which are expected to accelerate the development and commercialization of future smart clothes.

Martinez and his team have worked with the Purdue Research Foundation Office of Technology Commercialization to protect intellectual property. The innovations are patent pending.