In early 2017 BotFactory was contacted by a group of researchers with the North Carolina State University Fiber and Polymer Science Program, expressing interest and eventually acquiring one of our Squink PCB Printers. Roughly two years later they published an fantastic paper detailing how they managed to create high quality traces using reactive, particle-free inks on woven fabrics.
As they state, "The particle-free functional ink can conformally coat individual fibers to create a conductive network within the textile structure without changing the feel, texture, durability, and mechanical behavior of the textile.". Furthermore, the conductivity of the traces was equivalent to what is typically achieved using our FR-4 or Kapton sheets, reaching "0.2 ± 0.025 and 0.9 ± 0.02 Ω/□ on polyester woven and polyester knit fabrics is achieved, respectively."
Unlike other materials that have been tried, their described method is surprisingly durable. "There is no significant increase or change of the resistance observed over 10000 bending cycles, which is unprecedented for printed conductive textiles." Strain up to and above 100% of the fabric did not affect conductivitiy. However, multiple washcycles were not ideal for the fabric, increasing the sheet resistance to >1k/sq, although selecting a "tighter structure (less porous) can result in reduced sheet resistance and wash durability".
This breakthrough in wearable electronics is the kind of thing that makes BotFactory Squink or SV2 such a fantastic tool for researchers. For those companies and colleges considering work on smart fabrics, contact us to learn if we're the right fit for you. To read the original paper, click here. If you are interested in gaining full access, contact the original authors here.