Embedded MXene-coated glass fibres for impact damage detection in GFRP laminates: electrical real-time sensing and Thermal–THz diagnostics

In this work, an embedded Ti 3 C 2 T x MXene-coated glass fibre sensing architecture is developed to enable real-time detection and through-thickness assessment of impact damage in glass fibre-reinforced polymer (GFRP) laminates subjected to barely visible impact damage. Dual MXene-coated sensing layers were integrated near the top and bottom plies and subjected to low-velocity impacts, while electrical resistance changes were continuously monitored and correlated with mechanical response and damage mechanisms. The MXene-coated layers exhibited large irreversible piezoresistive responses, enabling discrimination between elastic deformation and damage-dominated behaviour. An asymmetry between the top and bottom sensing layers revealed penetration of damage through the laminate thickness, with the upper layer showing enhanced sensitivity to matrix cracking and delamination. To complement electrical monitoring, infrared thermography and terahertz (THz) time-domain spectroscopy were employed as diagnostic tools. Infrared thermography enabled visualisation of disrupted conductive pathways, while THz spectroscopy provided non-contact, depth-dependent characterisation of the embedded MXene layers and damaged regions, including improved detectability at higher impact energies. By integrating electrical sensing with thermal and THz diagnostics within an MXene-enabled composite system, this study establishes a multifunctional framework for impact damage detection and through-thickness assessment, offering a scalable pathway toward structural health monitoring of composite structures.