Screen-printed SWCNT/epoxy resin sensors with ultra-low SWCNT doping content: health monitoring of composite structures

Carbon nanocomposite sensors have great potential in structural health monitoring research for protecting material integrity and maintaining stable performance. However, the application of carbon nanocomposite sensors is limited by the poor dispersion of carbon nanotubes (CNTs), which results in high CNT penetration threshold and low processability of carbon nanocomposite sensors. Therefore, there is an urgent requirement for improving the dispersibility of CNTs to achieve efficient enhancement of carbon nanocomposite sensors. This work reports a highly sensitive and linear single-walled carbon nanotube (SWCNT)/epoxy resin (EP) sensor for structural health monitoring of composite materials using screen-printing process. Based on the favorable dispersibility of SWCNTs, the percolation threshold of SWCNTs in the sensor is merely 0.022 wt%, which is substantially lower than that in other studies. Moreover, the sensing properties are superior to those of other investigations. The sensor exhibits a remarkably high Gauge Factor (GF) of 17.3, indicating its exceptional reliability and consistency. Furthermore, the response/recovery times of 166/210 ms, respectively, under micro strain (ε<2 %), demonstrating its outstanding performance under minimal stress conditions. It also demonstrates a high linear response to temperature (R 2  = 0.99) and a GF of −5.0 × 10 −4  °C −1 . Impact tests on the sensor array of aircraft wall panels have validated the feasibility of SWCNT/EP sensors for impact localization and damage monitoring. These SWCNT/EP sensors with ultra-low SWCNT content hold great potential and broad application prospects in structural health monitoring, being anticipated to accurately conduct material damage assessment and structural integrity evaluation.