An April 2024 report in the journal
Science suggests that “smart” or “intelligent” textiles are a step closer to making the leap from the lab to real life
[1],
[2]. The study details an innovative fiber that gathers energy from the environment and uses it to send electrical signals and create light, without the need for batteries or chips. The advance yields textiles that can directly respond to users’ touch, opening new avenues for intelligent interaction between people and their environments, in addition to enabling potential medical, industrial, and consumer applications.
“This is a remarkable piece of work,” said Theodore Hughes-Riley, an associate professor in electronic textiles at the Nottingham Trent University in Nottingham, UK. “I have not seen a wireless system that can light up.”
Woven or cloth creations with an electronic component have been around for several decades. First-generation electronic textiles (e-textiles) have conductive wiring and circuitry between or on the outside of textile layers, like a heated blanket, and are controlled by devices affixed to the cloth. Second-generation e-textiles have electronic elements woven into the textile, like a heartrate-monitoring chest band, but still require separate components (with chips) and a power source, frequently batteries.
The newest generation of smart textiles are made of functional yarn woven into a cloth that can transmit signals, allowing them to sense, store, process, and communicate data between the fiber and the wearer
[3],
[4]. Because smart textiles integrate the electronics directly into soft, flexible fibers with typical fabric properties, they are permeable to air and water and do not excessively heat or cool, offering breathability and comfort while wearing
[5]. As e-textiles get smarter, the market for these wearable technologies could reach more than 21 billion USD by 2030, according to Grand View Research, a San Francisco, CA, USA-based market research and consulting firm
[6].
“Research into smart fibers and textiles has accelerated significantly since the 1990s,” said the Science paper’s first author Weifeng Yang, a doctoral candidate in materials science and engineering at Donghua University in Shanghai, China. “Recent advancements have led to the development of smart textiles that can perform tasks such as energy generation, temperature regulation, and even color changing based on environmental conditions.”
Uniquely, however, Yang and his colleagues’ work showcases smart fibers that harvest energy from the human body, eliminating the need for batteries
[1]. Their “i-fibers” collect electromagnetic energy from the environment by forming an energy circuit between the human body and the Earth. Also uniquely, the fibers directly convert this energy into radio frequency signals and visible light (
Fig. 1), without the chips that perform this function in other e-textiles. “Our chip-less e-textile system integrates specific functionalities directly into individual fibers,” Yang said. “This not only enhances the practicality of smart apparel in terms of distribution, comfort, and maintenance, but also improves its washability.”
The initial discovery that led to the i-fiber was an accident
[7]. In 2021, Yang began developing a light-emitting fiber intended to be powered by an alternating current signal. At one point the electrode fell off and Yang noticed that the fiber still glowed, suggesting that, surprisingly, a low-impedance energy path still existed despite the loss of a physical connection for ambient energy. “The energy-driven luminescent phenomena appear to occur spontaneously, as if by magic,” he said.
The environment is awash in electromagnetic fields created by wires delivering power to appliances, mobile phones, and other electronics. These fields exist, essentially, anywhere electricity flows. The researchers hypothesized that its novel fibers could serve as conduits for extracting and utilizing this untapped energy source, by leveraging the human body’s heightened relative conductivity compared to air.
The team’s i-fibers contain three layers. A silver-plated nylon inner layer acts as an antenna, inducing alternating electromagnetic fields. The middle layer—a dielectric composite resin composed of BaTiO
3—bolsters the electromagnetic coupling capacity. Finally, the outer layer consists of a luminescent ZnS composite resin that glows in the presence of electric fields
[1]. The i-fiber’s layers act together to convert electromagnetic energy from the environment into light and electrical signals that can be changed by adjusting the amount of fiber in contact with the body or the fiber diameter
[1]. An external sensing coil can pick up the signals and decode them into commands.
The i-fibers are thin and fine, Yang said, and when woven resemble commercial cotton fabrics. Because of the soft feel of the woven i-fiber, it has many potential uses and can be integrated into everyday items like clothing and home decor. “The textiles would be suitable in a wide range of applications, including consumer electronics and medical devices,” Yang said.
In one demonstration, the researchers created a haptic carpet that glows and transmits wireless signals when stepped on, a signal that could be used to, for example, turn on ambient lighting
[1]. The researchers also created clothing with an illuminated display to show words and patterns, with an interface allowing the wearer to write with their fingers on the cloth to update the display in real time, an innovation they speculated could help people with impaired hearing to communicate. They also used the technology for real-time control of virtual games. “We have used the wireless electrical signals generated by touching these fibers to invent a textile controller,” Yang said. “It controls game actions in real time, providing a breakthrough method of interacting with in-game content by simply touching a soft and lightweight fabric.”
The team additionally posits its i-fibers could be used to create garments that emit a glowing signal when the wearer nears or enters a potentially hazardous environment. The i-fiber is durable enough for use in harsh environments, Yang said, including vacuum, high pressure, extreme temperatures, and strong radiation. Its “ruggedness” makes the i-fiber particularly well-suited for deep space and deep-sea exploration. Yang said that it could be used in spacesuits, aerospace vehicles, and deep-sea probes, enabling such equipment to sense electromagnetic radiation, high-energy particle radiation, pressure, temperature, vibration, friction, collision, and other parameters.
Another potential use could be integration into robots and robotic prosthetics to collect comprehensive information on how humans and the objects around them interact. Such data, heretofore quite difficult to collect, could help in training robots to sense the environment and interact appropriately
[2].
Other researchers are working on using smart textiles in athletic, healthcare, and military applications. They can already capture biometrics in athletes such as heart rate and body temperature to track and enhance performance
[7]. Some groups are developing textiles that monitor body temperature and automatically adjust warmth
[7]. Smart textiles could also eventually enable monitoring of numerous health parameters, including body movement or levels of nutrients and biomarkers through the analysis of sweat
[5]. The US government has invested 22 million USD in a SMART ePANTS initiative to create clothing capable of recording audio, video, and location, garments intended to enhance the awareness of military and intelligence personnel in dangerous situations
[8].
While there are many exciting potential applications for smart textiles, there are still some challenges to their becoming a practical reality
[9],
[10]. Power is always an issue for anything mobile, and Yang et al.
[1] admit that the i-fiber’s energy-harvesting capability does not provide enough power for many applications, and that supplemental background electromagnetic fields may be needed. In addition, there is the problem of fluctuating power, which may ultimately mean that the steady energy supplied by batteries will be necessary.
Another big hurdle is automated manufacturing at scale, which remains largely an unknown. While manufacturing of complex materials like smart textiles would typically be expected to translate to high costs, this barrier may be lower for i-fibers. “The i-fiber materials do not require complicated synthesis steps, and the source materials are commercially available and inexpensive,” Yang said. “We have already mass-produced them.” The essential textile characteristics of i-fibers also make them compatible with industrial-scale manufacturing processes such as batch weaving and manipulation by digital sewing and embroidery machines (
Fig. 2)
[1],
[2]. They can even be dyed in different colors (
Fig. 3)
[1].
The Shanghai group’s work “should inspire the development of functional fibers and application of intelligent textiles across divergent fields. It also highlights applications to ubiquitous computing with sensing, displaying, and communication components weaved into the fabric of everyday life,” wrote Yunzhu Li and Yiyue Luo, assistant professors of computer science at the University of Illinois Urbana-Champaign, Urbana, IL, USA and electrical engineering and computer science at the University of Washington in Seattle, WA, USA, respectively, in an editorial accompanying the Yang et al. report
[2]. “There is great promise for intelligent textiles to transform the way humans live, work, and interact with the world.”
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