Nylon might seem the obvious go-to material for electronic textiles—not only is there an established textiles industry based on nylon, but it conveniently has a crystalline phase that is piezoelectric—tap it and you get a build-up of charge perfect for pressure sensing and harvesting energy from ambient motion.
Unfortunately, forming nylon into fibers while getting it to take on the crystal structure that has a piezoelectric response is not straightforward. “This has been a challenge for almost half a century,” explains Kamal Asadi, a researcher at the Max-Planck Institute for Polymer Research, Germany, and professor at the University of Bath, U.K. In a recent Advanced Functional Materials report, he and his collaborators describe how they have now finally overcome this.
The piezoelectric phase of nylon holds appeal not just for electronic textiles but all kinds of electronic devices, particularly where there is demand for something less brittle than the conventional piezoelectric ceramics. However, for decades, the only way to produce nylon with the crystalline phase that has a strong piezoelectric response has been to melt it, rapidly cool it and then stretch it so that it sets into a smectic δ’ phase. This produces slabs typically tens of micrometers thick—far too thick for applications in electronic devices or electronic textiles.
