Researchers from Chalmers University of Technology in Sweden have made a significant breakthrough in textile technology, presenting a silk thread coated with a conductive plastic that could transform everyday garments into power sources for health monitoring and electronic devices. This innovation addresses the challenge of finding materials that are both stable conductors of electricity and suitable for textile applications.

The new thermoelectric textiles harness temperature differences—such as that between the human body and the surrounding air—to generate electrical potential. This technology promises to eliminate the need for batteries in sensors that monitor various health metrics like movement and heart rate, offering a practical solution for powering devices worn close to the body.

The silk thread is coated with a conducting polymer, a type of plastic known for its electrical conductivity and compatibility with textiles. "The polymers we utilize are flexible, lightweight, and can be easily manipulated in both liquid and solid forms, while also being non-toxic," explains Mariavittoria Craighero, a doctoral student at Chalmers and the study's first author.

Through innovative methods, the researchers have developed a new type of electrically conductive thread with improved stability and conductivity. This advancement eliminates the need for metals, commonly used in previous studies, which can be affected by air exposure. "We discovered a newly identified polymer that performs excellently in air contact while maintaining strong electrical conductivity," Craighero notes.

To demonstrate practical applications, the researchers created two thermoelectric generators: a button sewn with the thread and a textile embedded with conductive threads. When placed between hot and cold surfaces, the generators displayed increasing voltage correlated to the temperature difference and conductive material amount. For instance, a larger textile piece generated about 6 millivolts at a 30-degree Celsius temperature difference, suggesting potential for charging portable electronics via a USB connector when combined with a voltage converter. Remarkably, the thread maintained its performance for at least a year and proved machine washable, retaining two-thirds of its conductive properties after seven washes.

However, the production of these thermoelectric textiles is still limited to laboratory conditions, requiring extensive manual sewing that takes several days. Yet, researchers remain optimistic about the thread's potential for automation and scalability in manufacturing processes. Professor Christian Müller, research leader of the study, states, "We have demonstrated the feasibility of producing conductive organic materials that fulfill the necessary functions for these textiles. This represents a significant advancement with enormous potential benefits for society."

Interest in organic electronics, particularly those utilizing conjugated polymers, has surged in recent years. These conducting polymers exhibit electrical properties akin to silicon while possessing the flexibility of plastics, making them ideal for a variety of applications, including solar cells, the Internet of Things (IoT), augmented reality (AR), and robotics. Chalmers University houses multiple research groups focused on this promising field.