A research team developed a thread made of conductive cellulose that offers practical possibilities for electronic textiles. Sewing the electrically conductive cellulose threads into a fabric using a standard household sewing machine, the researchers produced a thermoelectric textile that generates a small amount of electricity when it is heated on one side by a person's body heat. At a temperature difference of 37 °C, the textile can generate around 0.2 microwatts of electricity.
The thread was made conductive by dyeing it with an electrically conductive polymeric material. Measurements show that the dyeing process gives the cellulose thread high conductivity that can be increased even further through the addition of silver nanowires. In tests, the conductivity was maintained after several washes.
Applications for electronic textiles include healthcare, where functions such as regulating, monitoring, and measuring various health metrics could be beneficial. In the wider textile industry, where conversion to sustainable raw materials is a vital ongoing question, natural materials and fibers have become an increasingly common choice to replace synthetics. Electrically conductive cellulose threads could have a significant role to play.
The electrically conductive yarn is produced in a layer-on-layer coating process with an ink based on the biocompatible polymer polyelectrolyte complex poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS). The e-textile thread measures high conductivity for cellulose thread in relation to volume of 36 S/cm-, which can be increased to 181 S/cm by adding silver nanowires. The thread coated with PEDOT:PSS can handle at least five machine washes without losing its conductivity. By integrating the cellulose yarn into an electrochemical transistor, the researchers have also been able to demonstrate its electrochemical function.