Transferred and embedded patterns of laser-induced graphene for broadband and load-bearing radar absorbing structures

초록

Conventional frequency-selective surface (FSS)-based radar-absorbing structures (RAS) are commonly fabricated using filler-loaded polymers or metal-patterning processes, which can restrict pattern design flexibility, scalability, and structural integration. This study presents a transferred laser-induced graphene (LIG) FSS for glass fiber-reinforced polymer (GFRP)-based RAS. LIG was formed on polyimide film by CO2 laser direct lasing and transferred onto GFRP prepregs using a roll-transfer process. The transferred patterns were then embedded in the GFRP laminate. Ridge and groove regions produced by overlapping laser pulses showed different graphitic characteristics, leading to an anisotropic conductive pathway. Sheet resistance measurements confirmed that the LIG network was more connected along the laser-scan path, resulting in lower sheet resistance parallel to the scan path than perpendicular to it. The sheet resistance decreased with increasing areal energy density and followed an inverse power-law relationship. An indirect method was used to estimate the effective sheet resistance of embedded LIG after curing, and the extracted values were used to design the RAS. The fabricated RAS had a thin profile of 2.91 mm and achieved more than 90% absorption across the X-band. Different resonance peaks under 0° and 90° polarizations were attributed to the anisotropic sheet resistance of LIG. Short-beam shear tests showed that the GFRP-based RAS retained interlaminar shear strength comparable to pristine GFRP. These results show that transferred LIG-FSS patterns provide a scalable route for fabricating thin, broadband, and load-bearing GFRP-based RAS, while expanding LIG from surface conductive layers to embedded metasurface layers in structural composites. © 2026 Elsevier Ltd

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