CO2 sensing at room temperature using carbon nanotubes coated core fiber Bragg grating

• Published in: Review of scientific instruments Vol. 84; no. 6; p. 065002
• Main Authors: Shivananju, B N, Yamdagni, S, Fazuldeen, R, Sarin Kumar, A K, Hegde, G M, Varma, M M, Asokan, S
• Format: Journal Article
• Language: English
• Published: United States 01.06.2013
• ISSN: 1089-7623
• DOI: 10.1063/1.4810016

The sensing of carbon dioxide (CO2) at room temperature, which has potential applications in environmental monitoring, healthcare, mining, biotechnology, food industry, etc., is a challenge for the scientific community due to the relative inertness of CO2. Here, we propose a novel gas sensor based on clad-etched Fiber Bragg Grating (FBG) with polyallylamine-amino-carbon nanotube coated on the surface of the core for detecting the concentrations of CO2 gas at room temperature, in ppm levels over a wide range (1000 ppm-4000 ppm). The limit of detection observed in polyallylamine-amino-carbon nanotube coated core-FBG has been found to be about 75 ppm. In this approach, when CO2 gas molecules interact with the polyallylamine-amino-carbon nanotube coated FBG, the effective refractive index of the fiber core changes, resulting in a shift in Bragg wavelength. The experimental data show a linear response of Bragg wavelength shift for increase in concentration of CO2 gas. Besides being reproducible and repeatable, the technique is fast, compact, and highly sensitive.