Non-additive polymer matrix coated rGO/MXene inks for embedding sensors in prepreg enhancing smart FRP composites

Two-dimensional (2D) nanosheets are promising nanomaterials that can be used as sensing elements in numerous applications such as wearable devices, machine tools, and aircraft; however, challenges remain in achieving high sensitivity, wide frequency sensing range, and reliability after long cyclic loading. Suitable ink formulations and preparation parameters for embedded sensors while retaining the structural integrity of the host structure should be determined. In this work, we demonstrated a synergistic combination of L-cysteinereduced graphene oxide and MXene (LGM) inks in the absence of an additional polymer matrix to establish noninvasive conditions for embedding sensors in prepreg fiberglass/epoxy for smart composites with sensing capabilities. This sensor offers a high gauge factor of 47-1400 in different tensile strain ranges, with unnoticeable changes in the outstanding mechanical properties of the host glass fiber-reinforced polymer (GFRP) laminate. Long-term fatigue three-point bending tests were performed at different frequencies and bending angles, demonstrating excellent durability and stability. The corresponding sensors can also capture vibration signals in the low-high-frequency ranges. The nonintrusive embedment of sensors in GFRP laminates using the new coated non-additive polymer matrix LGM ink successfully preserves the mechanical properties of the host, including its structural integrity, with outstanding sensing performance for low-to-high-frequency signals.