Development and Sensitivity Analysis of rGO-TiO₂ Coated eFBG Sensor for the Detection of Ethanol in Petrochemicals

In this article, a newly developed reduced Graphene Oxide (rGO) – Titanium Dioxide (TiO ₂ ) coated on a Fiber Bragg grating (FBG) based sensor is presented for the detection of ethanol in Petrochemicals i.e., Petrol and Diesel are reported. An experimental procedure has been carried out to find the adulteration level of ethanol in petrochemicals. Initially, the FBGs were etched using 40% concentrated hydrofluoric acid to interact with the outer medium and then coated with an optically active thin film to enhance the sensing abilities. Furthermore, the addition of rGO layer served as a large surface area due to which a significant further shift in the Bragg wavelength was observed. The sensitivity calculation of the proposed sensor is found to be better than the etched FBG (eFBG) and TiO ₂ -coated eFBG sensor. The final sensitivities achieved are 5.91 nm/RIU and 6.32 nm/RIU with the increment of 9% and 13% in petrol and diesel, respectively. Also, the proposed sensor is temperature insensitive due to the double coated layer of thin film and the Limit of Detection (LOD) of the sensor is found to be ${2.19}\times {10} ^{\text {-3}}$ RIU for petrol and ${2.05}\times {10} ^{\text {-3}}$ RIU for diesel, respectively. The characterizations of the sensor are also done using XRD, FESEM, Raman Spectroscopy, UV-VIS-NIR Spectroscopy, and 3D Optical profiler. This work will significantly improve the petrochemical industry’s ability to detect adulteration using eFBG-based fiber optic sensors.