Concentration-Tunable Liquid Graphene Oxide Magneto-Optical Sensor for Smart Grid Current Monitoring

Current sensors based on solid-state materials often suffer from magnetic saturation and stress-induced birefringence, limiting their performance in high-current applications. To address these issues, this paper proposes a tunable liquid-phase magneto-optical sensing scheme utilizing the Faraday effect in Graphene Oxide (GO) dispersions. A transmission-mode detection system utilizing a "Differential Baseline Subtraction" algorithm was constructed to isolate intrinsic magneto-optical characteristics from parasitic solvent interferences. Experimental results demonstrate a giant specific Verdet constant of 1.72×〖10〗^4 rad/(T∙m) in the ultra-dilute regime, confirming superior intrinsic efficiency. Through a comprehensive trade-off analysis between sensitivity and stability, 0.008 wt% was identified as the optimal engineering concentration. This configuration achieves a sensitivity of -0.00391 mV/mT and high linearity (R^2>0.98), while suppressing hysteresis error to 6.57%, thereby effectively mitigating the instability observed at the lower concentrations. Furthermore, the mechanisms of "Concentration Quenching" and "Structural Locking" are elucidated to explain non-linear responses at higher densities. This research validates the feasibility of GO dispersions for high-fidelity, range-configurable current monitoring in Smart Grids.