High-Sensitivity CO2 Sensor Based on a Graphene Oxide Coated Long-Period Fiber Grating.

This study presents the development and characterization of a novel carbon dioxide (CO2) sensor based on graphene oxide (GO)-coated long-period fiber grating (LPFG). The structural and chemical properties of GO were analyzed using Raman spectroscopy and scanning electron microscopy (SEM), revealing a defective structure with a high degree of oxidation and significant surface roughness, which enhances gas adsorption capabilities, making it highly suitable for CO2 detection. The sensor's performance was evaluated across CO2 concentrations ranging from 5 to 65%. The operational principle of the sensor is based on changes in the resonance wavelength induced by variations in the refractive index of the GO coating as it interacts with CO2 molecules. Results indicate a notable sensitivity of 0.0643 nm/% and low hysteresis during adsorption and desorption processes, affirming its stability and reliability. Additionally, the sensor demonstrated a strong linear fit of approximately 96% in adsorption and desorption cycles (5-65 and 65-5%). These findings underscore the significant potential of the GO-coated LPFG sensor for practical CO2 sensing applications, offering advantages such as immunity to electromagnetic interference and ease of integration into remote sensing technologies.