Is this Light-Up Fiber the Future of Smart Clothing?

Yang Weifeng places an ordinary-looking thread in water, then watches as it lights up like an electrified fluorescent tube. When woven into a fabric, the entire swatch illuminates at a touch, as though his finger were a magic wand.

But Yang’s glowing cloth isn’t magic; it’s the product of a concerted effort by researchers at the Advanced Functional Materials Group (AFMG), part of Donghua University in Shanghai. The results, which were published in Science this April, represent a potentially significant step toward wearable computers.

The paper was also a major achievement for Donghua, which had been trying for years to get one of its researchers published in the pages of a top-two scientific journal. But Yang, a doctoral student at the school’s College of Materials Science and Engineering, seems uncomfortable with his sudden rise to on-campus fame. Soft-spoken and slightly awkward, he seems to hail from grad student central casting. According to his own description, he was never even all that interested in materials science.

So how did he find himself published in the pages of one of its most prestigious journals?

As Yang tells it, materials science was his fallback major — an alternative to the medical training preferred by his parents. Although he excelled at his undergraduate program at Wuhan University of Science and Technology in central China, he failed the postgraduate entrance interview at Fudan — one of China’s top-ranked universities — landing at Donghua instead.

Once there, he applied to study silicon-based solar cells, in part because he believed the field offered better job prospects after graduation. Once again, however, he was disappointed: the school assigned him to its Advanced Functional Materials Group, one of 10 research groups at Donghua aligned with national research priorities, some of which consist of over 100 doctoral and master’s students under the guidance of a handful of experienced scholars.

This utilitarian approach to student placement is common at Chinese schools, says Hou Chengyi, a researcher at Donghua, advisor to the AFMG, and one of Yang’s coauthors. “If a student expresses dislike for their assigned direction, we usually ask them to persevere,” Hou tells Sixth Tone. “Just because you don’t like it doesn’t mean the direction is not good, and the fact that you don’t like it now doesn’t mean you won’t like it in the future.”

Working with his advisers, Yang quickly published a number of papers in prestigious journals including Nature Communications and Advanced Materials. “He is very meticulous and diligent,” says Yang’s doctoral supervisor, Zhang Qinghong.

In 2021, Yang Weifeng began work on an experimental light-emitting fiber. The idea was to connect an AC signal to a conductive layer of the fiber, then place another electrode on the fiber’s surface to create an electric field between them, causing the fiber to emit light.

But when the electrode clip accidentally fell off during an experiment, Yang noticed that touching the fiber would still cause it to emit light. Yang repeated the experiment several times, and the phenomenon persisted.

But why?

Yang brought this question to AFMG’s next meeting — held every three weeks, where all the mentors and students convene to exchange their results and talk over any challenges they face.

After some analysis, his mentors arrived at a preliminary conclusion: the absence of a physical connection allows for a low-impedance pathway for dissipating electromagnetic energy, illuminating the fiber.

They saw additional value in Yang’s accidental discovery. The ubiquity of electromagnetic fields and waves represents a wealth of untapped energy. Leveraging the human body’s heightened relative conductivity compared to air, it could serve as a conduit for harvesting and utilizing this otherwise dissipated electromagnetic energy.

A specialized research team was formed to harness the potential of what they called “human coupling.” If it worked, it could result in smart clothing without the need for charging or batteries, powered solely by the wearer’s own body.

Key to the project was selecting the right materials. Although he was the lone graduate student on the research team, Yang spearheaded most of the experimental work. Finally, after three years of trial and error, they found their answer: a smart fiber with a three-layer sheath-core structure. The fiber’s core layer serves as an antenna, detecting alternating electromagnetic fields, while the middle layer — a dielectric composite resin — bolsters the electromagnetic coupling capacity. Finally, an outer layer of electric field-sensitive luminescent material allows the fiber to glow.

Arguably the most important implication of Yang’s discovery is in the field of smart wearables, as it paves the way for clothes that aren’t just “battery-free,” but also “chip-free.”

According to Wang Hongzhi, a member of the research team, contemporary smart clothing predominantly uses silicon-based chips to process information and oversee an array of devices attached to the clothes. “As more components converge into a single garment, however, its comfort diminishes significantly,” Wang says. “Moreover, as demands for additional functions surge, the burden on the garment escalates. You end up lugging around a hefty circuit board, rendering the clothing impractical for daily wear.”

The team’s newly developed smart fiber opens up new possibilities. Liberating fibers from chips, batteries, or other electronics can greatly simplify their architecture and allow them to be washed.

Currently, their fiber is only capable of emitting light. Nonetheless, the research team sees it as a monumental leap; with the foundational principle established, future applications can now be explored.

According to Zhang, smart clothing could be the future of public transportation, allowing passengers to signal for a stop by performing a gesture instead of hitting a button. To Wang, they offer the potential to monitor bodily function in real time, like a smartwatch: “If your body is inflamed, your clothes could sound the alarm, based on a chemical analysis of your sweat.”

As for Yang, despite being the study’s lead author, he is the most reluctant to speculate on the future of his invention, saying only that his paper has made it easier for him to find a postdoctoral position. As for what he will do during his postdoc and afterward? “We’ll see,” he says.

(Header image: Visuals from Yang Weifeng, reedited by Sixth Tone)

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