Carbon nanomaterials based films for strain sensing application - a review

Abstract

Strain sensors have been increasingly pervasive in modern life, owing to their ability to detect, respond and convert mechanical motion into an electrical signal, which can be measured in terms of electrical resistance. Novel strain sensing applications have broadened the technology scope and allow us to monitor the changes in the surroundings in distinctive ways we could barely imagine. In recent years, the development of carbon nanomaterials (CNMs) based films for sensing applications has been growing at an astounding pace, owing to their outstanding electrical and mechanical properties. Specifically, the fabrication of CNMs-based films provide groundbreaking approaches for the realization of highly flexible and sensitive strain sensors. In fact, strain sensors based on carbon nanomaterials (CNMs) (e.g., carbon nanotubes, graphene, carbon black, carbon nanofibers) can overcome the limitations of conventional metallic strain gauges, such as low sensitivity (GF ∼ 2), poor stretchability (ε<5%), fragile, geometrical and functional restrictions. This comprehensive article critically reviews the state-or-the-art CNMs-based strain sensors, with special emphasis on their fabrication techniques and performances (sensitivity and maximum strain) of strain sensor produced. The performances of each type of CNMs strain sensor are reviewed to determine the type of CNMs-based films, type of polymer substrate and fabrication technique best suited for producing flexible strain sensors with high sensitivity. Finally, the challenges that impair the commercialization of CNMs-based strain sensor, along with possible solutions and their future outlook are addressed.