In situ SEM studies on strain sensing mechanisms of PPy-coated electrically conducting fabrics

This paper studies a flexible fabric strain sensor from PPy-coated fabrics prepared by a chemical vapor deposition method under low temperature, placing an emphasis on mechanisms of its strain sensing behavior. In situ tensile tests in a scanning electron microscope (SEM) were conducted for PPy-coated electrically conducting yarns, which were prepared by the same procedure as that for the PPy-coated fabrics, enabling it possible to observe in situ the phenomena that occurred on the fiber surface during fabric deformation. The investigation revealed that the PPy-coated nylon/polyurethane fabrics exhibited a high strain sensitivity of over 400 and very large workable strain range greater than 50%, which mainly attributes to the high conductivity and crack-opening and crack-closing mechanisms of PPy-coated polyurethane yarn, as well as the excellent properties of knitted fabric structure.