Copper nanoparticle-doped laser-induced graphene based microwave acetone sensor

Traditional microwave sensors often suffer from limited sensitivity and high signal attenuation due to the insufficient conductivity of sensing materials. To address these challenges, we proposed a high-performance room-temperature acetone sensor based on a synergistic material-structure design strategy. The design process centers on the synthesis of a copper nanoparticle-doped laser-induced graphene (LIG-Cu) composite via a precise in-situ secondary laser-induced thermal reduction method. This approach ensures the uniform anchoring of metallic copper nanoparticles onto the three-dimensional porous graphene skeleton. The primary advantage of this design is that the copper doping effectively bridges the graphene flakes, significantly mitigating the inherent ohmic losses of pristine LIG and enhancing the resonator’s quality factor (Q-factor). Concurrently, a square-nested split-ring resonator (SNSRR) architecture was optimized to concentrate electromagnetic energy within the sensing gap, thereby maximizing the interaction between the analyte gas and the sensing film. Experimental results in the 20–100 ppm acetone concentration range reveal a significant resonant frequency shift of 0.759 MHz and a magnitude variation of 2.474 dB. The sensor exhibits a high sensitivity of 0.0282 dB/ppm with excellent linearity (R² = 0.97256), rapid response/recovery times, and remarkable 30-day stability. This work provides an efficient and scalable solution for high-sensitivity VOC detection at room temperature.