A U-shaped microfiber ring laser sensor for ultrasensitive detection of Ni2+ ions

Shi Qiu; Bengang Chang; Liang Chai; Wenjia Nie; Lijiao Zu; Yutao Liu; Ying Han; Wei Wang; Xinghu Fu; Jinhui Yuan; Qiang Wu

doi:10.1016/j.talanta.2025.128547

A U-shaped microfiber ring laser sensor for ultrasensitive detection of Ni²⁺ ions

Talanta. 2025 Jul 3;297(Pt A):128547. doi: 10.1016/j.talanta.2025.128547. Online ahead of print.

Authors

Shi Qiu¹, Bengang Chang², Liang Chai², Wenjia Nie², Lijiao Zu², Yutao Liu², Ying Han², Wei Wang², Xinghu Fu², Jinhui Yuan³, Qiang Wu⁴

Affiliations

¹ School of Information Science and Engineering, the Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao, 066004, China. Electronic address: qiushi325@ysu.edu.cn.
² School of Information Science and Engineering, the Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province, Yanshan University, Qinhuangdao, 066004, China.
³ State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing, 100876, China.
⁴ Faculty of Engineering and Environment, Northumbria University, Newcastle upon Tyne, NE1 8ST, United Kingdom. Electronic address: qiang.wu@northumbria.ac.uk.

PMID: 40617020
DOI: 10.1016/j.talanta.2025.128547

Abstract

As a common heavy metal pollutant, Ni²⁺ necessitates a rapid, sensitive, and accurate detection method to mitigate its impact on human health and the environment. This study developed a U-shaped single mode-tapered four core-single mode (STFS) based fiber ring laser (FRL) sensor coated with Ni²⁺ ion-imprinted chitosan (Ni²⁺-II-CS) for Ni²⁺ detection. Experimental results demonstrate that the average spectral stability in deionized water is 0.016 nm over 60 min. The detection time for Ni²⁺ is less than 8 min, with a limit of detection (LoD) as low as 1 nM. The proposed U-shaped STFS-based FRL sensors also show good selectivity, displaying limited cross-reactivity to other common heavy metal ions, including Cu²⁺, Cr²⁺, Pb²⁺, and Cd²⁺. Additionally, the analytical findings from pond and tap water specimens demonstrate wavelength shifts of -23.30 % and -27.06 %, respectively, when compared with measurements in deionized water. These findings indicate that the proposed microfiber sensor may have potential applications in heavy metal ion detection and environmental monitoring.

Keywords: Environmental monitoring; Fiber ring laser sensor; Ion imprinting technology; Ni(2+) detection; U-shaped microfiber sensor.