Thermally and electrically conductive multifunctional sensor based on epoxy/graphene composite

Flexible electronics is expected to be one of the most active research areas in the next decade. In this study, a mechanically strong and flexible epoxy/GnP composite film was fabricated having percolation threshold of electrical conductivity at 1.08 vol% GnPs and high thermal conductivity as 1.07 W m-1 K-1 at 10 vol% GnPs. The composite film shows high mechanical performance: Young's modulus and tensile strength were improved by 1344% and 66.7%, respectively at 10 vol%. The film has demonstrated high sensitivity to various mechanical loads: (i) it has gauge factors of 2 at strain range 0–7% and 6 at range 7–10% (ii) it gives good electrical response with bending and twisting angles up to 180o; and (iii) it displays a good compressive load response up to 2N where the absolute value of electrical resistance change increased by 71%. Furthermore, the film has showed an excellent reliability up to 5.5×103 cycles with minor zero-point error. Above 20 oC, the film solely acts as a temperature sensor; upon cyclic temperature testing, the film demonstrated a stable resistive response in the range of 30 −75 oC with a temperature sensitivity coefficient of 0.0063℃-1. This flexible composite film has remarkable properties that enable it to be used as a full-fledged sensor for universal applications in aerospace, automotive and civil engineering.