Crack detection of metal structures is an important procedure to ensure the safe operation of metal structures. In this work, a metal crack sensor based on a highly conductive flexible graphene film is proposed. The sensor is designed based on conformal microstrip antenna composed of a flexible graphene film radiation patch and a flexible dielectric substrate. The prepared sensor exhibited a detection sensitivity of 36.82 MHz/mm demonstrated by both experimental and simulation results. Moreover, benefiting from the flexible nature of the graphene film, the proposed sensor shows good conformality which makes up the shortcoming of the traditional rigid crack detection device.

In this paper, a conformal CSRR derived sensor array with two resonant frequency based on graphene assembled film (GAF) is proposed to detect and determine the direction of submillimeter cracks on aluminum plates. The GAF sensor array consists of a microstrip line, a dielectric substrate and a reference ground with two CSRR derived resonant structure. The GAF sensor array has a high sensitivity of 270 MHz for the curved aluminum plate with a crack width of 0.2 mm. In addition, the CSRR derived resonant structure array of GAF sensor is effectively detect the direction of crack.