Chemically functionalised suspended-core fibre for ammonia gas detection

Liu, Liangliang; Tang, Zijuan; He, Chenyang; Korposh, Serhiy; Lou, Shuqin; Morgan, Stephen P.

Abstract

An optical fibre ammonia gas sensor utilising a functionalised four-leaf-clover-shaped suspended-core fibre (SCF) is demonstrated. The fibre is functionalised by depositing a thin layer of an ammonia sensitive dye (tetraphenylporphyrin tetrasulfonic acid hydrate) on the wall of the inner cavities of the SCF through capillary action. An in-line fibre sensing structure is designed for light transmission through the SCF and also allows gas exchange with the atmosphere through two porous polyethylene housings. The sensing structure exhibits a temperature-dependent transmission due to the thermal expansion of the housings. A ratiometric method is applied for signal processing which is demonstrated to reduce significantly the effect of temperature change in the tested range (20-30 C). The sensor is tested in ammonia concentration ranges from 0-10 ppm and demonstrates capability of detecting ammonia at ppb levels. The minimum tested concentration is 150 ppb in the experiment with a calculated limit of detection of 20 ppb. The sensor response time (T10-90%) is 160 s and it is demonstrated to be reusable after treatment with hydrogen chloride vapour. Numerical simulation of evanescent absorption features of such an SCF indicates that approximately 0.02% of the optical power exists in the air holes for the fundamental propagation mode. Distinctive absorption bands observed in the transmission spectrum of the fabricated sensor can also be observed in the simulated model after adding the TPPS absorption layer in the holes.

Citation

Liu, L., Tang, Z., He, C., Korposh, S., Lou, S., & Morgan, S. P. (2021). Chemically functionalised suspended-core fibre for ammonia gas detection. Journal of Lightwave Technology, 39(15), 5197-5205. https://doi.org/10.1109/JLT.2021.3083094

• Journal Article Type: Article
• Acceptance Date: May 20, 2021
• Online Publication Date: May 25, 2021
• Publication Date: Aug 1, 2021
• Deposit Date: May 24, 2021
• Publicly Available Date: May 25, 2021
• Journal: Journal of Lightwave Technology
• Print ISSN: 0733-8724
• Electronic ISSN: 1558-2213
• Publisher: Institute of Electrical and Electronics Engineers
• Peer Reviewed: Peer Reviewed
• Volume: 39
• Issue: 15
• Pages: 5197-5205
• DOI: https://doi.org/10.1109/JLT.2021.3083094
• Public URL: https://nottingham-repository.worktribe.com/output/5569370
• Publisher URL: https://ieeexplore.ieee.org/document/9439950
• Additional Information: © 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works