Reviewed by Lexie CornerNov 1 2024
A research team led by Chalmers University of Technology in Sweden has presented a common silk thread coated with a conductive plastic material that exhibits promising properties for converting textiles into electrical generators, according to a study published in Advanced Science.
A research group led by Chalmers University of Technology in Sweden presents an ordinary silk thread coated with a conductive plastic material that shows promising properties for turning textiles into electricity generators. Here, a button is sewn with the new thread. Image Credit: Hanna Magnusson
Imagine a sweater that charges a cell phone while running or powers devices to monitor health. The development of such textiles is challenging due to a lack of materials that are both suitable for clothing and reliably conductive.
Thermoelectric textiles can harness temperature differences—such as those between our bodies and the surrounding air—to generate electrical potential. This technology offers significant benefits for both society and daily life. By connecting these textiles to sensors, they can power devices without batteries, enabling functions like heartbeat monitoring or movement tracking.
To be worn close to the body, the materials must meet strict safety and flexibility standards. The researchers tested silk thread coated with a conductive polymer, a plastic material with a chemical structure that makes it both electrically conductive and suitable for textile applications.
The polymers that we use are bendable, lightweight and are easy to use in both liquid and solid form. They are also non-toxic.
Mariavittoria Craighero, Study First Author and Doctoral Student, Department of Chemistry and Chemical Engineering, Chalmers University of Technology
Enhanced Stability and Conductivity
The electrically conductive thread was developed using techniques from previous studies within the same project. Initially, metals were incorporated into the thread to maintain stability when exposed to air. Since then, researchers have progressed toward creating the thread using only organic (carbon-based) polymers. In this latest study, they have developed a new type of thread with enhanced electrical conductivity and improved stability.
Craighero added, “We found the missing piece of the puzzle to make an optimal thread – a type of polymer that had recently been discovered. It has outstanding performance stability in contact with air, while at the same time having a very good ability to conduct electricity. By using polymers, we don't need any rare earth metals, which are common in electronics.”
To demonstrate the practical application of the new thread, the researchers created two thermoelectric generators: a button sewn with the thread and a piece of fabric with threads sewn in. When placed between a hot and a cold surface, the voltage on the measuring device increased, indicating energy generation from the temperature difference.
The results varied depending on the amount of conductive material in the textile and the temperature difference. For example, with a 30-degree Celsius difference, the larger fabric piece generated around six millivolts.
Theoretically, with a voltage converter, this setup could be used to charge portable devices via USB. The researchers also demonstrated that the thread maintains its performance for at least a year and is machine washable.
“After seven washes, the thread retained two-thirds of its conducting properties. This is a very good result, although it needs to be improved significantly before it becomes commercially interesting,” Craighero added.
Can Meet Functions That These Textiles Require
Producing the thermoelectric fabric and button is only possible in a lab setting, as the material must be crafted and sewn by hand, a time-intensive process. For example, sewing the demonstrated fabric took four days of meticulous needlework. However, the researchers are optimistic about the thread's potential and believe that scaling up production and developing an automated manufacturing process is achievable.
We have now shown that it is possible to produce conductive organic materials that can meet the functions and properties that these textiles require. This is an important step forward. There are fantastic opportunities in thermoelectric textiles, and this research can be of great benefit to society.
Christian Müller, Study Research Leader and Professor, Department of Chemistry and Chemical Engineering, Chalmers University of Technology
More About the Study
Mariavittoria Craighero, Qifan Li, Zijin Zeng, Chunghyeon Choi, Youngseok Kim, Hyungsub Yoon, Tiefeng Liu, Przemysław Sowiński, Shuichi Haraguchi, Byungil Hwang, Besira Mihiretia, Simone Fabiano and Christian Müller are the study authors.
The researchers work at Chung-Ang University, Linköping University, and Chalmers University of Technology in Seoul, South Korea.
The research was funded by the EU’s Horizon 2020 research and innovation program through the Marie Skłodowska-Curie project HORATES, the Knut and Alice Wallenberg Foundation, the European Research Council (ERC), the Swedish Research Council, and Linköping University.
Journal Reference:
Craighero, M. et. al. (2024) Poly(benzodifurandione) Coated Silk Yarn for Thermoelectric Textiles. Advanced Science. doi.org/10.1002/advs.202406770