Design of Divergence Beam‐Based Surface Plasmon Resonance Sensor With High Measurement Performance for Petrol Adulteration Using TiO2/Ag/ZnTe Multilayers
Jordan Hakim Hossea, Athuman Omary Mfinanga, Vitalis John MwinyiABSTRACT
Detection of petrol adulteration at low concentration (5%) with high sensitivity is challenging. We propose a multilayer surface plasmon resonance (SPR) sensor (BK7/TiO 2 /Ag/ZnTe) optimised for petrol adulteration detection. At a silver thickness of 37 nm, the sensor achieves sensitivity = 491.30°/RIU, figure of merit = 116.42 and Detection Accuracy (DA) = 0.2370 at 40% kerosene concentration; and sensitivity = 330.43°/RIU, FOM = 63.94, DA = 0.1634 at 5% kerosene concentration. The optical energy coupling efficiency of 98.58% at 37 nm silver thickness is 39.4%, 68.5%, 101.7% and 177.6% higher than at 40, 45, 50 and 55 nm, respectively. Again, with 37 nm of Ag, the highest electric field along x interacts with the measured sample as compared to the traditional thickness (40–55 nm). A divergence beam reflected onto a 3648‐pixel CCD with 12‐bit ADC yields an angular resolution of 6.694 × 10 − 8 ° Δ θ res (99.98% improvement over mechanical scanning at 0.001° resolution) and a refractive index resolution of 7 × 10 − 10 RIU. Sensitivity and detection accuracy show improvements of 18% and 5.61%, respectively, over recently published SPR petrol adulteration sensors.