Fuel classification and adulteration detection using a highly sensitive plasmonic sensor

Abstract

In this paper, a plasmonic refractive index sensor is proposed based on a square ring-type resonator with gratings, which is coupled with a straight metal-insulator-metal (MIM) waveguide that has two triangular stubs. The adulteration of fuel may have detrimental effects on a variety of systems, including automobiles, people's health, and even the environment, in addition to reducing fuel economy. That is why this sensor has been designed for classifying different types of fuels and detecting the extent of adulteration in fuel. The finite element method (FEM) has been applied for numerical analysis of the structure. The sensor monitors the changes in the resonant wavelength and how light passes through the resonator to figure out the unknown material's refractive index. The sensor exhibits high sensitivity, and the maximum achievable sensitivity is 3270.3 nm/RIU with a figure of merit (FOM) of 31.154, when the refractive index of the dielectric is 1.01 and the sensor is functioning in mode-4. For mode-1, both the FOM and the quality factor are found to have their highest values, 45.28 and 46.508, respectively. According to the simulation results for different ranges of refractive index, when analyzing values between 1.3 and 1.4, the sensitivity reached its peak at 3138.8 nm/RIU. This means that while operating in mode-4, it is suitable for use in bio-sensing applications. Furthermore, our new sensor can detect change in the temperature in a broad spectral range using the wavelength-dependent refractive index of ethanol with a maximum achievable temperature sensitivity of 1.159 nm/°C.