Detection of biofuel adulterants using an optical fiber-based refractive index sensor

Abstract

This study presents a Lossy Mode Resonance (LMR) based on fiber optic sensor for detecting biofuel adulteration. Tin Oxide (SnO2), coated over the clad removed portion of the optical fiber using the Radio Frequency Magnetron sputtering technique, was utilized as the sensing layer. The fabricated sensor probe was analyzed with various concentrations of the analytes that include methanol in ethanol, ethanol in methanol, methanol in water, ethanol in water, water in methanol, and water in ethanol. The absorption spectra of the fabricated sensor probe revealed two LMR peaks namely, LMR1 and LMR2 that exhibited wavelength shift under varying concentration of the analytes. The maximum sensor responses for the above combinations of the analytes were 4.95%, 3.30%, 3.00%, 3.56%, 2.91% and 3.57%, respectively. The sensitivities of the sensor probe towards these analytes were 0.46 nm/vol%, 0.17 nm/vol%, 0.49 nm/vol%, 0.58 nm/vol%, 0.08 nm/vol%, and 0.4 nm/vol%, respectively. The real time sample were examined using metal oxides coated sensors. The result exhibits SnO2 coated probe is sensitive than other probes.