Polypyrrole-Coated Graphene Oxide-Doped Polyacrylonitrile Nanofibers for Stretchable Strain Sensors

Stretchable yarn strain sensors demonstrate incomparable advantages for application in wearable electronic devices, such as health monitors, interfaces for human–computer interactions, and flexible robots, because of their good flexibility and ease of integration with other components and fabrics. In this study, a graphene oxide (GO)-doped polyacrylonitrile nanofiber-coated hybrid yarn with a uniformly wavy structure was used as the elastic substrate, and an in situ polymerized polypyrrole conductive polymer was applied to the nanofiber surface to construct a highly stretchable yarn strain sensor. The obtained sensor exhibited an advantageous wavy structure, which endowed it with a wide monitoring range of 0–500%. The large number of nanofibers in the wave also provided a large contact area, which endowed the sensor with an outstanding resistance change of 173.13 under stretching. In addition, the sensor could monitor the bending deformation; the bending sensitivity was 16.6 at a bending degree of 4 cm. Meanwhile, the sensor exhibited stable cycle durability, and only a small sensitivity loss rate was evident after 10,000 cycles during stretching and bending. In addition, the sensor exhibited ideal weaveability and integration and could be easily woven into any fabric. Significantly, it could monitor human muscle vibration and body movement, indicating its high potential for application in wearable electronic devices.