Resistance-type strain sensor based on carbon nanofiber/polypyrrole composite membrane with high sensitivity

Carbon nanofibers have been widely studied as one of the promising materials for fabricating flexible electronic strain sensors. Surface modification of carbon nanofibers by conducting polymers is a simple yet effective approach to constructing strain sensors with good conductivity and sensitivity. In this work, composite nanofiber membranes composed of carbon nanofiber and conducting polymer are developed via in situ polymerization of pyrrole, aniline, and thiophene respectively on the surface of the carbon nanofiber which serves as a substrate. Different composite membranes, CNF@PANI, CNF/Ppy, and CNF@PTh, are successfully manufactured. The conducting polymer-carbon nanofiber composite membranes exhibit improved conductivity as well as response sensitivity compared to pristine carbon nanofiber membranes. Among different composite membranes being studied, CNF/Ppy demonstrates the highest strain-sensing performance. It shows good sensitivity, reproducibility, and stability in detecting both subtle (strain = 0.1%) and large (strain = 25%) deformation. The excellent strain-sensing performance of CNF/Ppy endows the composite membrane with great potential for applications in wearable electronics. Highlights Adding PANI, Ppy, and PTh could improve the conductivity of the CNF sensor. Ppy doping has a good effect on the performance of the CNF strain sensor. CNF/Ppy strain sensor has high sensitivity, stability, and durability. CNF/Ppy sensors can detect deformation caused by human movement. CP-CNF composite material has good flexibility and mechanical properties.