Interconnected concentric ring resonator-based plasmonic sensor for ethanol blending detection in fuels

Abstract

A concentric circular ring resonator with a dual stub-based plasmonic sensor configured in Metal Insulator Metal arrangement is investigated in this article. While many recent studies have achieved high sensitivity at the expense of reduced figure of merit (FOM), the proposed sensor is optimized to attain high sensitivity as well as an excellent FOM also. The numerical analysis initially reveals a maximum sensitivity of 1725 nm /RIU and an FOM of 25.7. However, by optimization of geometric parameters, such as mutual gap between the concentric ring (MG), gap between the waveguide and resonator (WG), and stub thickness, the sensor achieves a sensitivity of 1336 nm/RIU with a FOM of 61 in near- infrared region at shorter wavelengths. This optimization offers valuable insights into how these parameters influence its sensing characteristics. The excellent sensing parameters enable the sensor to detect even minimal changes in refractive index, making it suitable for biosensing applications. The sensor demonstrates its ability to identify various types of fuels through refractive index sensing. The sensor further highlights its potential by precisely detecting the concentration of ethanol in ethanol-blended petrol (EBP) and ethanol–diesel (E-diesel), both of which are emerging as promising sustainable alternatives to traditional fossil fuels.