Tri-Level Wrinkle-Vein-Sheet Structured Reduced Graphene Oxide/Nanofiber Films for Flexible Piezoresistive Sensors

For practical applications, it is critically necessary to develop piezoresistive sensors with high sensitivity, low detection limit, extensive detection range, short response and recovery time, and good durability. In this paper, a novel high-performance piezoresistive sensor is tactfully fabricated based on a tri-level wrinkled-vein-sheet structured reduced graphene oxide (rGO)/nanofiber film. The rGO/nanofiber film is prepared by a combination of high-conductivity rGO, polyacrylonitrile (PAN) nanofibers, and elastic VHB tape, in which rGO is first coated on short PAN nanofibers to form a flexible film and then combined with the bidirectional prestretching method to build a composite film with a random wrinkled structure. The influence of a short nanofiber addition amount and prestretching ratio on the device performance is investigated in detail. Due to the contribution of nanofibers and wrinkled structures to the contact sites, the obtained piezoresistive sensor shows excellent performance, including an ultrahigh cycling durability of 30,000 s, a wide detection range of 2.83 Pa–23.81 kPa, and a high sensitivity of 318.14 kPa–1 at 0–2.83 kPa. More importantly, the prepared sensor can accurately recognize human activities such as touching, chewing, vocalizing, and fist clenching, which is expected to exhibit significant potential for application in future flexible wearable electronic devices.