Hybrid Electrochemical-Surface Plasmon Resonance Microfiber Sensor for Pb2+ Detection

High-sensitivity detection of heavy metal ions in solution is critical for environmental monitoring. In this paper, a dual-mode method namely hybrid electrochemical-surface plasmon resonance (SPR) microfiber sensor, is proposed for the detection of Pb ²⁺ . Gold-coated indium tin oxide (ITO) is used as a working electrode, and a gold nanofilm-coated microfiber is attached to the ITO electrode to monitor the electrochemical reaction process in real time. The microfiber-based SPR sensor is sensitive to slight refractive index changes on the surface and can monitor the electrochemical deposition process and striping process on the electrode. It is shown that a broad dynamic detection range changing from 10 ^-12 to 10 ^-6 M can be achieved, and the limit of detection can reach to the order of pM. The proposed dual-modal detection can provide voltage, current, and optical information simultaneously, making the detection of heavy metal ions more accurate and intuitive. Additionally, the proposed hybrid electrochemical-SPR detection method has the advantages of small size, flexible shape, and cost-effectiveness, which can be potentially used for hazard and hard-to-reach environments.