Category: TECHNOLOGY AND INNOVATION
Country: Sweden
08th March, 2025.
By StudyFinds Staff
Reviewed by Steve Fink
Research led by Christian Müller, Chalmers University of Technology
In a nutshell
-Scientists finally cracked the code on making fabric that can generate electricity from body heat by creating a special polymer coating for silk that stays stable for over a year—previously, similar materials would degrade within days when exposed to air.
-This isn’t just lab-perfect technology—the coated silk yarn can survive through seven rounds in the washing machine while still keeping most of its electrical properties, and it can stretch quite a bit without breaking.
-While we’re not charging smartphones with our t-shirts just yet (the power output is still very low), this breakthrough could realistically power small sensors embedded in clothing, like health monitors that wouldn’t need battery changes or charging.
GOTHENBURG, Sweden -Forget to bring your charger with you on vacation? What if your clothing could generate electricity from the heat your body naturally produces? This futuristic concept is now approaching reality thanks to scientists at Chalmers University of Technology in Sweden and Linköping University.
Researchers say the remarkable new textile technology converts body heat into electricity through thermoelectric effects, potentially powering wearable devices from your clothing. The innovation, described in an Advanced Science paper, centers on a newly developed polymer called poly(benzodifurandione), or PBFDO, which serves as a coating for ordinary silk yarn.
“The polymers that we use are bendable, lightweight and are easy to use in both liquid and solid form. They are also non-toxic,” says study first author Mariavittoria Craighero, a doctoral student at the Department of Chemistry and Chemical Engineering at Chalmers, in a statement.
Unlike previous attempts at creating thermoelectric textiles, this breakthrough addresses a critical barrier that has long hampered progress: the lack of air-stable n-type polymers. These materials are characterized by their ability to move negative charges and are essential counterparts to the more common p-type polymers in creating efficient thermoelectric devices.
“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,” explains Craighero.
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. (Credit: Chalmers University of Technology | Hanna Magnusson)
Thermoelectric generators work by converting temperature differences into electrical energy. When one side of a thermoelectric material is warmer than the other, electrons move from the hot side to the cold side, generating an electrical current. The human body continuously generates heat, creating natural temperature gradients between the skin and the surrounding environment.
For efficient thermoelectric generation, both p-type (positive) and n-type (negative) materials must work together. While p-type materials have been well-established in previous research, creating stable n-type materials has been a persistent challenge. Most n-type organic materials degrade rapidly when exposed to oxygen in the air, often becoming ineffective within days.
What makes this development particularly exciting is the remarkable stability of PBFDO-coated silk. Unlike similar materials that degrade within days when exposed to air, these new thermoelectric yarns maintain their performance for over 14 months under normal conditions without any protective coating. The researchers project a half-life of 3.2 years for these materials – an unprecedented achievement for this type of organic conductor.
Beyond electrical performance, the mechanical properties of the PBFDO-coated silk are equally impressive. The coated yarn can stretch up to 14% before breaking and, more importantly for everyday use, it can withstand machine washing.
“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,” states Craighero.
The material also demonstrates remarkable temperature resilience. During testing, the researchers found that PBFDO remains flexible even when cooled with liquid nitrogen to extremely low temperatures. This exceptional mechanical stability allows the material to withstand various environmental conditions and physical stresses that would be encountered in real-world use.
SEM micrographs of a) the cross section of neat and b) a side view of PBFDO coated silk yarn sputtered with gold, and c,d) the cross section of silk yarn coated with PBFDO (no gold sputtering). (Credit: Advanced Sciences)
To showcase the technology’s potential, the research team created two different thermoelectric textile devices: a thermoelectric button and a larger textile generator with multiple thermoelectric legs.
The thermoelectric button demonstrated an output of about 6 millivolts at a temperature difference of 30 degrees Celsius. Meanwhile, the larger textile generator achieved an open-circuit voltage of 17 millivolts at a temperature difference of 70 degrees Celsius.
With a voltage converter, this could help power ultra-low-energy devices, such as certain types of sensors. However, the current power output—0.67 microWatts at a 70-degree temperature difference—is far below what would be required for USB charging of standard electronics.
While these power outputs mark a major step forward in thermoelectric textiles, it’s important to note that the temperature differences used in lab tests—up to 70 degrees Celsius—are significantly higher than what would typically be experienced in everyday clothing. This means real-world performance may be lower than laboratory results suggest.
Despite current limitations in power output, the technology shows particular promise for healthcare applications. Small sensors that monitor vital signs like heart rate, body temperature, or movement patterns could potentially operate using this technology, eliminating the need for battery changes or recharging.
For patients with chronic conditions requiring continuous monitoring, self-powered sensors embedded in clothing could provide valuable data without the hassle of managing battery life. Similarly, fitness enthusiasts could benefit from wearables that never need charging, seamlessly tracking performance metrics during activities.
Beyond health monitoring, the technology could eventually support other low-power functions in smart clothing, such as environmental sensing, location tracking, or simple LED indicators. As power conversion efficiency improves, applications could expand to include more power-hungry features.
Currently, the production process is time-intensive and not suitable for commercial manufacturing, with the demonstrated fabric requiring four days of manual needlework to produce.
“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,” says Christian Müller, Professor at the Department of Chemistry and Chemical Engineering at Chalmers University of Technology and research leader of the study.
One key challenge identified through computer simulations is the electrical contact resistance between components. Reducing this resistance could potentially increase power output by three times or more. The researchers also investigated how factors like thermoelectric leg length and thread count affect performance, providing valuable insights for future designs.
Interest in these types of conducting polymers has grown significantly in recent years. They have a chemical structure that allows them to conduct electricity similar to silicon while maintaining the physical properties of plastic materials, making them flexible. Research on conducting polymers is ongoing in many areas such as solar cells, Internet of Things devices, augmented reality, robotics, and various types of portable electronics.
Imagine your clothing one day being capable of keeping your smartphone charged as you move.
(AI-generated image created by StudyFinds)
What’s clear is that there is a viable pathway toward practical thermoelectric textiles that can function reliably in everyday conditions. By addressing both the electrical and mechanical requirements for textile integration, this work bridges the gap between laboratory demonstrations and potential real-world applications.
The development of these polymers also aligns with sustainability goals by eliminating the need for rare earth metals commonly used in electronics. With further refinement and scaling of the manufacturing process, this technology could eventually lead to clothing that powers our devices using nothing but our body heat.
For widespread adoption, researchers will need to develop automated production methods that can efficiently coat and assemble the thermoelectric textiles at scale. Additionally, improving power output while maintaining stability remains a critical goal for future research.
The researchers coated ordinary silk thread with PBFDO polymer by dipping it into a specially formulated ink and drying it multiple times. They constructed two test devices: a button sewn onto wool fabric and a larger generator with 16 thermoelectric legs sewn through felt wool. Performance was measured by placing these devices between surfaces of different temperatures and recording the electricity generated.
The PBFDO-coated silk achieved impressive stability, maintaining conductivity for over 14 months in normal conditions with a projected half-life of 3.2 years. It withstood stretching up to 14% and survived seven machine washings while retaining two-thirds of its conductivity. The larger textile generator produced 0.67 microwatts at a 70K temperature difference, while computer simulations suggested that optimizing electrical contacts could significantly boost performance.
Power output remains low, suitable only for very low-power devices. Lab testing used temperature differences (up to 70K) much higher than typical real-world conditions, meaning actual performance would likely be lower. Production is currently time-intensive, requiring four days of manual work for a single demonstration piece. While stability is impressive compared to other similar materials, some degradation still occurs over time, particularly after washing.
This research represents a breakthrough in creating stable n-type materials for thermoelectric textiles, potentially enabling practical applications in wearable technology. The work provides valuable insights for optimizing future designs, particularly regarding electrical contact resistance. By eliminating the need for rare earth metals, these organic materials also support sustainability goals. While commercial products are still years away, this development represents a significant step toward self-powered electronic textiles.
The research was supported by the European Union’s Horizon 2020 program (Marie Skłodowska-Curie grant), the Knut and Alice Wallenberg Foundation, the European Research Council, the Swedish Research Council, and Linköping University. Author Simone Fabiano is disclosed as a co-founder and chief scientific officer of n-ink, a company with potential interests in the technology.
Published in Advanced Science (2024) as “Poly(benzodifurandione) Coated Silk Yarn for Thermoelectric Textiles” by researchers from Chalmers University of Technology, Linköping University, and Chung-Ang University. Available as an open-access paper under Creative Commons Attribution License.
Research led by Christian Müller, Chalmers University of Technology.
Courtesy: studyfinds.org
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