New conductive, cotton-based fiber developed for smart textiles

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A single strand of fiber developed at Washington State University has the flexibility of cotton and the electrical conductivity of a polymer called polyene.

The newly developed material showed good potential for wearable e-textiles. The WSU researchers tested the fibers with a system that drives LED light and another system that senses ammonia gas. Journal of Carbohydrate Polymers.

„We have a fiber in two sections: one side is regular cotton: flexible and strong enough for everyday use, and the other side is a conductive material,” said Hong Liu, a WSU textile researcher and corresponding author of the study. „Cotton can support a conductive material that can provide the desired functionality.”

Although more development is needed, such fibers should be integrated into clothing with flexible circuits as sensor attachments. These patches can be part of uniforms for firefighters, soldiers, or workers who handle chemicals to detect hazardous exposures. Other applications include health tracking or fitness shirts that can do more than current fitness monitors.

„We have some smart wearables like smart watches that can track your movement and human vital signs, but we believe that in the future your everyday clothes can also perform these functions,” Liu said. „Fashion is not only about color and style, as many people think about it: fashion is science.”

In this study, the WSU team worked to overcome the challenges of blending the conductive polymer with cotton cellulose. Polymers are substances consisting of very large molecules that have repeating patterns. In this case, the researchers used polyaniline, also known as PANI, a synthetic polymer with conductive properties already used in applications such as printed circuit board manufacturing.

Inherent conductivity makes polyaniline brittle and cannot, by itself, be made into a textile fiber. To solve this, the WSU researchers dissolved cotton cellulose from recycled T-shirts into one solution and a conductive polymer into another separate solution. These two solutions are combined and the material is extruded to form a filament.

The result showed good interfacial bonding, meaning molecules from different materials held together through stretching and bending.

Achieving the right composition at the interface of cotton cellulose and polyaniline is a delicate balance, Liu said.

„We wanted these two solutions to work so that when the cotton and conductive polymer come into contact with each other they mix with a certain amount of glue, but we don’t want them to mix too much, otherwise the conductivity will be reduced,” she said.

Note: Liu W, Liu H, Zhao Z, Liang D, Zhong WH, Zhang J. A novel structural design of cellulose-based conductive composite fibers for wearable e-textiles. Carbohydrate polymn. 2023;321:121308. doi: 10.1016/j.carbpol.2023.121308

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