Hydrous Ethanol Detection Using a Graphene Oxide-Coated Fresnel Reflection Sensor

Ethanol accounts for approximately half of all biomass fuel production, being one of the most important renewable fuel sources. To meet the requirements for ethanol concentration monitoring, we propose a graphene oxide (GO)-coated fiber optic (FO) sensor. The ethanol concentration is derived from the Fresnel reflection intensities from the interface between the sensor head and surrounding hydrous ethanol. The molecular enrichment properties of GO improved the sensitivity and concentration measurement range of the sensor. We observed fast linear responses with an average sensitivity of 0.08 dB/% in all the 0-100% concentration range, satisfying the requirements for hydrous ethanol monitoring.