Piezoresistive laser-induced graphene as a low-cost strain sensor for composite structures
Xue Chen, Khong Wui Gan, Suan Hui Pu, Meisam Jalalvand, Andrew Hamilton
Abstract
Laser-induced graphene (LIG) has emerged as a versatile material with significant potential across diverse sensing applications owing to its excellent electrical conductivity and ease of synthesis. This study investigates the piezoresistive characteristics of LIG when embedded within glass fiber-reinforced composites as a low-cost strain sensor. Cyclic tensile tests were performed across varying strain ranges, revealing the presence of a critical strain point beyond which physical changes or damage in the internal conductive network of the LIG start to become significant. At low strains up to 0.2%, the electrical resistance change in LIG shows a linear relationship with the applied strain, achieving a gauge factor up to 133. Further monotonic tensile tests at high strains revealed highly nonlinear behavior in piezoresistivity, which can be attributed to developed damage within the LIG microstructure. The nonlinear piezoresistivity can be approximated by a phenomenological model integrating geometric changes in the LIG and the random void model for describing the developed damage within the LIG network. The model provides insights into the piezoresistivity of the embedded LIG in a composite laminate and serves as a design tool for LIG strain sensors, underscoring its potential for structural health monitoring in composite materials.