New oil derivative refractive index sensor using ribbon of multi-walled carbon nanotubes

Abstract

In this work, we propose a new liquid refractive index (RI) sensor based on one-dimensional (1D) regular array of multi-walled carbon nanotubes (MWCNTs) for sensing oil derivatives (ODs), for the first time. The proposed sensor is a ribbon consisting of 10 MWCNTs grown inside an AAO (Al2O3) template as the host material, which can sense the change of host material RI with high precision up to △n = 0.0015 corresponding to the sensitivity S = 930 nm/RIU. Replacing the host material with ODs changes the reflection in the range of visible wavelengths. The reflection spectrum of sensor is calculated for the RI range of 1.3888–1.5306 belonging to various ODs. The RI difference △n = 0.1418 between Butanol (C4H10O) and Nitrobenzene (C6H5NO2) host materials results in 130 nm wavelength shift. By removing one or two cylinders of MWCNTs and creating a point defect within the sensor structure, whereas ODs are injected into the defect area, we achieved a sensitivity up to 430 nm/RIU. The proposed sensor with un-reactive nature of MWCNTs can be used in environments with high temperature and pressure such as oil refinery industry.