Research on a fiber sensing system for metal ion detection based on SPF-PCF-SPF structure and coated LPFG

In order to provide a method for accurately detecting the concentration and types of heavy metal ions in water, a fluid ion detection system is designed. It consists of a side-polished fiber-assisted fluid structure and a long-period fiber grating (LPFG) coated with a metal chelating agent membrane. In this study, both theoretical and experimental investigations are conducted to examine the sensing characteristics of the system towards copper ion and iron ion solutions. The results demonstrate that under the premise of ensuring solution flow, the system can achieve specific identification of different types of heavy metal ions. Furthermore, it exhibits concentration sensing sensitivities of 9.23×10 4 mL·nm/mol and 7.13×10 4 mL·nm/mol for copper sulfate (CuSO 4 ) and ferric chloride (FeCl 3 ) solutions, respectively. Therefore, this sensing system offers the potential for real-time detection of metal ions.