Sewing Thermoelectronics into Regular Textile - hero image

Cellulose thread could lead to sustainable electronic textiles

Image credit: Anna-Lena Lundqvist/Chalmers University of Technology

A research team in Sweden has developed a thread made of renewable conductive cellulose, which they say could provide a range of practical possibilities for the production of sustainable electronic textiles.

Electronic textiles offer revolutionary new opportunities in various fields, in particular healthcare. But to be sustainable, they need to be made from renewable and natural materials. The cellulose thread, created by a research team led by the Chalmers University of Technology, could offer huge potential as a material for electronic textiles in a range of applications while using non-toxic, renewable, and natural materials in the production process.

“Miniature, wearable, electronic gadgets are ever more common in our daily lives. But currently, they often depend on rare, or sometimes toxic, materials. They are also leading to a gradual build-up of great mountains of electronic waste. There is a real need for organic, renewable materials for use in electronic textiles,” said Sozan Darabi, a doctoral student at the Department of Chemistry and Chemical Engineering at Chalmers.

Together with Anja Lund, a researcher in the same group, Darabi has been working with electrically conductive fibres for electronic textiles for several years. They initially focused on using silk, but now the researchers have taken further discoveries through the use of cellulose.

Sewing the electrically conductive cellulose threads into a fabric using a standard household sewing machine, the researchers developed a thermoelectric textile that produces a small amount of electricity when heated on one side – for example, by a person’s body heat.

Renewable Cellulose Textile with Thermoelectronic Properties - inline image

The dark yarn is the cellulose yarn and the lighter one is a commercially available silver-plated yarn, both of which are electrically conductive. The researchers have sewn the two threads separately into the fabric, in a special way that gives the fabric its thermoelectronic properties.

Image credit: Anna-Lena Lundqvist/Chalmers University of Technology

They found that at a temperature difference of 37°C, the textile can generate around 0.2 microwatts of electricity. “This cellulose thread could lead to garments with built-in electronic, smart functions, made from non-toxic, renewable, and natural materials,” Darabi said.

The researchers developed the production process for the cellulose thread with the help of co-authors from Aalto University in Finland. And in a subsequent process, the Chalmers researchers made the thread conductive by dyeing it with an electrically conductive polymeric material.

The researchers’ measurements from this showed that the dyeing process gives the cellulose thread a record-high conductivity – silver nanowires were also found to increase this conductivity even further. In tests, the thread maintained conductivity after several washes.

According to experts, electronic textiles could improve our lives in several ways. One important area is healthcare, where functions such as regulating, monitoring, and measuring various health metrics could be hugely beneficial.

Close up of the Conductive Cellulose Yarn - inline image

The cellulose thread is a renewable and non-toxic electrically conductive material for electronic textiles that can be sewn in an ordinary household sewing machine. It has a record-high conductivity for cellulose yarn and can handle at least five washes without losing its conductivity.

Image credit: Anna-Lena Lundqvist/Chalmers University of Technology

In the wider textile industry, where conversion to sustainable raw materials is a vital ongoing question, natural materials and fibres have become an increasingly common choice to replace synthetics. Electrically conductive cellulose threads could have a significant role to play here too, the researchers said.

Christian Müller, research leader for the study, said: “Cellulose is a fantastic material that can be sustainably extracted and recycled, and we will see it used more and more in the future. And when products are made of uniform material or as few materials as possible, the recycling process becomes much easier and more effective.

“This is another perspective from which cellulose thread is very promising for the development of e-textiles,” explained Müller, who is also a professor at the Department of Chemistry and Chemical Engineering at Chalmers.

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