Student thesis led to conductive thread

​The two master students, Sozan Darabi and Sandra Hultmark, doing their Master thesis in Professor Christian Müller’s research group at Chalmers, developed an electrically conductive thread that they then wove into a keyboard with help from a handicraft association in Gothenburg. Now they publish their results in the magazine Advanced Materials Technologies.

The wire is completely free from metal. It consists of silk dyed with an electrically conductive plastic. The researchers have developed a "dye" for textiles that both dyes fabrics and threads beautifully blue, while at the same time making them electrically conductive. The electrically conductive component is a kind of polymer or plastic which, when dissolved in water, has a low pH which makes it firmly stick on silk. This makes the threads withstand both abrasion and washing after staining.

The textile takes a step closer to smart clothes with built-in features, without metals or other materials that affect the feeling of fabric. The thread could also be used for embroidered circuit boards in fabric.

“With an electrically conductive silk wire comes new possibilities for designing textile electronics, which can be used for, for example,  pulse and movement sensors, fully integrated in clothing. One can also imagine sewing a keyboard that can easily be rolled up and put in the pocket”, says Dr. Anja Lund, who is part of the Christian Müller research group.

In order to successfully weave the thread into a fabric, Chalmers went to the handicraft association Göteborgs Hemslöjdsförening, because of their good looms and great weaving experience.

“The handicraft association has been crucial for this project, since we have had to combine new materials with traditional crafts. We also have machine-embroidered electrically conductive patterns out of the wire, with help from the company ACG Nyström in Borås. It is a very nice thing to be able to use local knowledge in our work, "says Anja Lund.

The researchers now want to move on and combine the conductivity in the thread with their previous research findings, where they developed textiles that generate electricity from heat. Together, this could lead to smart clothes that use the body heat to support the features with electricity.

Text: Mats Tiborn​