Laser-induced graphene fibre sensors for structural health monitoring of polymeric composites

Laser-induced graphene (LIG) technology has offered an innovative and convenient approach to produce porous graphene structures through a one-step laser scribing process from some polymer precursors. In this paper, continuous and freestanding graphene fibres were fabricated from micron-sized polyimide (PI) single filaments by laser irradiation. The morphology and microstructure of laser-induced graphene fibres (LIGFs) were characterized by scanning electron microscopy (SEM), Raman spectroscopy and transmission electron microscopy (TEM). The sensing properties of the freestanding LIGF sensor was evaluated by electromechanical coupling tensile test and shown excellent gauge sensitivity with a gauge factor of ∼5.5. With embedding the sensor into fiberglass prepreg laminates, only by the measurement of the electrical resistance, its use for multipurpose sensing in life-long (from manufacturing to failure) structural health monitoring (SHM) of high-performance polymeric composites was demonstrated. In the resin curing process, the resistance change of the embedded sensor provides valuable resin curing information. After integrated curing, the same sensor is able to map the strain/stress states and detect the failure of the host composite. In addition, the embedded sensor also is capable of monitor the damage accumulation in the fatigue loading.