Architecture of conductive fibers in pigtails for high‐sensitivity monitoring of structural health in fiber‐reinforced composites

Abstract Structural health monitoring is vital for improving the safety and reliability of fiber‐reinforced composites. However, it is still challenging to achieve high sensing performance without changing the overall properties of composites. In this work, conductive fibers were braided into pigtails to achieve high sensing sensitivity and maintain low electrical resistance. Conductive pigtails with hierarchical and critically connected percolation networks were integrated with basalt fabric by an embroidery technique to realize self‐diagnosis of composites. After being embedded in epoxy composites, the material exhibited low electrical resistance (128.8 kΩ) and excellent sensing performance, demonstrating a high Gauge factor of 8.1, good linearity (R² > 99%) and stability. The experimental results also showed that conductive pigtails can sensitively inform crack initiation and growth inside composites, which is extremely important for warning of the risk of material fractures. In addition, the mechanical strength of the material was almost unchanged before and after the pigtails were embedded. All these results indicate that conductive pigtails could be used as highly sensitive sensors for realizing structural health monitoring in fiber‐reinforced composites. Highlights CBs/TPU pigtails with hierarchical conductive paths were fabricated and firmly integrated with basalt fabric by the embroidery technique. There is a good interface between the pigtails and the matrix, resulting in the embedding of the pigtails with little change in the mechanical properties of the composites. Pigtails can sensitively detect crack initiation and growth in composites, demonstrating the potential for self‐diagnosis of fiber‐reinforced composites.