Electrostatic Twisting Of Core-Shell Nanofibers For Strain Sensing Applications

Stretchable strain sensors are increasingly needed in emerging fields of wearable electronics and smart textiles for applications ranging from human motion detection to health monitoring. Nanofibers made from conductive materials or composites of polymers and conductive nanoparticles exhibit strong sensitivities but are difficult to be utilized because of their small dimensions. In the present article we report on a technique for producing core-shell nanofibers and their in situ twisting using a rotating electric field. The process produces sensitive threads that can be handled easily and used, for instance, in smart textile applications. The core-shell nanofibers utilized poly(vinylidene fluoride) as the structural polymer, and multiwalled carbon nanotubes were used to make the core electrically conductive. The structure of nanofibers was studied through a set of analytical methods. The fibers exhibit strong piezoresistive responses and can be utilized in various strain sensing applications. The mechanical properties of fabricated submicron fiber yarns are compared with nontwisted fibers, and improvement of their stretchability has been demonstrated. Furthermore, the sensitivity of fiber threads to different directions of stretching depending on the way of their knitting into fabric has been compared.