A Fibre-Optic Platform for Sensing Nitrate Using Conducting Polymers

Sensors

Heike Ebendorff-Heidepriem¹  Drew Evans²  Soroush Shahnia³  Shahraam Afshar³ 

[1] ARC Centre of Excellence for Nanoscale Biophotonics, Institute for Photonics and Advanced Sensing, The University of Adelaide, Adelaide, SA 5000, Australia;Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia;Laser Physics and Photonic Devices Laboratories, UniSA STEM, University of South Australia, Mawson Lakes, SA 5095, Australia;

关键词: nitrate sensing;    optical fibre;    PEDOT;    conducting polymer;   

DOI  :  10.3390/s21010138

来源: DOAJ

【 摘 要 】

Monitoring nitrate ions is essential in agriculture, food industry, health sector and aquatic ecosystem. We show that a conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), can be used for nitrate sensing through a process in which nitrate ion uptake leads to oxidation of PEDOT and change of its optical properties. In this study, a new platform is developed in which a single-mode fibre coated at the tip with PEDOT is used for nitrate sensing. A crucial step towards this goal is introduction of carbonate exposure to chemically reduced PEDOT to a baseline value. The proposed platform exhibits the change in optical behaviour of the PEDOT layer at the tip of the fibre as it undergoes chemical oxidation and reduction (redox). The change in optical properties due to redox switching varies with the intensity of light back reflected by the fibre coated with PEDOT. The proposed platform during oxidation demonstrates linear response for the uptake of nitrate ions in concentrations ranging between 0.2 and 40 parts per million (ppm), with a regression coefficient $R^2=0.97$ and a detection limit of 6.7 ppm. The procedure for redox switching is repeatable as the back reflection light intensity reaches $\pm 1.5\%$ of the initial value after reduction.

【 授权许可】

Unknown