| Summary: | The monitoring of heavy metal ions content has positive significance for water resources quality monitoring and environmental protection. Herein, a tapered microfiber sensor functionalized polydopamine/4-mercaptopyridine (PDA/4-MPY) film for detection of trace mercury ion (Hg2+) concentration in water is proposed and demonstrated. The microfiber interferometer has excellent sensing performance including a refractive index (RI) sensitivity response of 1146 nm/RIU and a low-cross temperature response of −0.03 nm/℃. Hg2+ heavy metal ion is captured by the surface functional film to affect the RI of the microfiber surface, which lead to the wavelength shift of the interference spectrum. Experiments demonstrate that the sensor has an obvious regular response to Hg2+ in the range of 0–100 nM, in which the sensitivity reaches 1.015 nm/nM in the range of 0–10 nM with a high reliability (R2 = 0.99). This sensor has high sensitivity response and strong specific recognition to trace Hg2+ concentration under the advantages of simple fabrication and low cost. Furthermore, the success of the proposed sensor also indicates that the combination of microfiber and nanomaterial has a bright prospect in the field of optical detection.
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