There are many potential applications for conductive "smart fabrics," but typically, specialized fibers are not as soft and flexible as those made from common materials. However, an experimental new double-sided fiber is both soft and conductive. The fiber, developed by a team of scientists at Washington State University, is made from two substances: cotton cellulose extracted from recycled T-shirts and an existing conductive synthetic polymer called polyaniline.
The single-strand fiber combines the flexibility of cotton with the conductivity of a polymer called polyaniline. Shows good potential in wearable electronic textiles. Researchers at Washington State University detailed their findings in the journal Carbohydrate Polymers.
Polyaniline is too brittle when combined with cotton cellulose to form a usable fiber on its own. That is, the two materials are not simply mixed into a homogeneous mixture. If so, the polyaniline would be diluted to the point where it loses its conductivity.
To solve this problem, researchers at Western Sydney University dissolved cotton cellulose extracted from recycled T-shirts into one solution and conductive polymers into a separate solution. The two solutions are then combined side by side and the material is extruded to create a fiber.
In this study, the WSU team worked to overcome the challenges of mixing conductive polymers with cotton cellulose. A polymer is a large molecule with a repeating pattern. In this case, the researchers used polyaniline (also known as PANI), a synthetic polymer with conductive properties that is already used in applications such as printed circuit board manufacturing. The results showed that the interface was well bonded, meaning molecules from different materials stayed together during stretching and bending.
"We split a fiber into two parts: one side is traditional cotton: flexible and strong enough for daily use, while the other side is a conductive material," said Liu Hang, the study's corresponding author and a textiles researcher at Western Sydney University. "The cotton supports the conductive material, which provides the desired functionality."
Although more development work is needed, the researchers' idea is to integrate such fibers into clothing as sensor patches with flexible circuits. The patches could become part of the uniforms of firefighters, soldiers or workers handling chemicals to detect exposure to dangerous substances. Other applications include health monitoring or sports shirts that can do more than current fitness monitors.
A research paper led by Associate Professor Liu Hang was recently published in the journal Carbohydrate Polymers. Other authors of the study include first author Liu Wangcheng, Zhao Zihui, Liang Dan, Zhong Weihong and Zhang Jinwen. This research was supported by programs from the National Science Foundation and the Walmart Foundation.
Liu said: "There are already some smart wearable devices, such as smart watches that can track your movements and human vital signs, but we hope that in the future your daily clothing can also implement these functions. Fashion is not just about color and style as many people think, fashion is science."