Ion-Imprinted Chitosan-Based Interferometric Sensor for Selective Detection of Heavy Metal Ions

• Published in: Journal of lightwave technology 2019-06, Vol.37 (11), p.2778-2783
• Main Authors: Ravikumar, Raghunandhan, Li Han Chen, Hui, Melissa Meow Xin, Chi Chiu Chan
• Format: Article
• Language: English
• Subjects: Calcium ions; Chitosan; Copper; Crosslinking; Crystal fibers; Epichlorohydrin; fiber-optic interferometric sensor; heavy metal ion sensor; Heavy metals; Interferometry; ion imprinting; Ions; Metal ions; Nickel; Optical fiber sensors; photonic crystal fiber (PCF); Photonic crystals; Refractive index; Sensitivity; Sensitivity analysis; Sensors; Splicing; Surface treatment
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2018.2874171

A photonic crystal fiber (PCF)-based Mach-Zehnder interferometric sensor using ion-imprinted chitosan for the detection of Ni 2+ ions is proposed and experimentally demonstrated. The sensor was fabricated by splicing a small section of the PCF between single-mode fibers. Nickel-adsorbed chitosan was crosslinked with epichlorohydrin (ECH) to increase its mechanical strength, and thereby, to improve the sensor stability and was subsequently imprinted with Ni 2+ ions. The sensor was coated with nickel ion imprinted chitosan and was examined with test solutions of various Ni 2+ concentrations. The sensor exhibits a Ni 2+ detection sensitivity of 0.0632 nm/μM (nanometer per micromolar) in the linear range and a limit of detection of 0.57 μM. The cross sensitivity of the sensor was evaluated to other metal ions like Cu 2+ , Ca 2+ , and Na + and also by comparing its performance to a sensor using nonimprinted chitosan. Results have shown better sensor response to Ni 2+ ions over other metal ions and an improvement in performance over a nonimprinted chitosan sensor. Investigation was also carried out to examine the effect of crosslinking on the sensor performance by varying the ECH to the chitosan molar ratio (5:1, 10:1, and 15:1) and the sensor achieved its best performance when the molar ratio was 10:1.