Detection of heavy metal ions Hg2+ and Pb2+ based on surface plasmon resonance technique with enhanced sensitivity

In this study, we present a high-performance surface plasmon resonance (SPR)-based metal-ion sensor employing a BK7 glass prism/BaTiO₃/gold (Au) hybrid structure. The BaTiO₃ layer, characterized by its high real dielectric constant, is strategically incorporated to enhance light–matter interaction at the metal–dielectric interface. Using the angular interrogation method, key sensing performance parameters-sensitivity (S), detection accuracy (DA), quality parameter (QP) and electric field intensity enhancement factor (EFIEF)-are systematically analyzed. The strong dielectric response of BaTiO₃, when coupled with the plasmonic properties of gold, significantly improves the confinement of the evanescent field, thereby enhancing the sensing capability of the device. For Hg²⁺ ion detection, the proposed structure demonstrates a sensitivity of 1410 RIU⁻¹, a detection accuracy of 0.178, and a quality parameter of 23.77 RIU⁻¹. In the case of Pb²⁺ ion detection, the achieved sensitivity, detection accuracy, and quality parameter are 1390.43 RIU⁻¹, 0.166, and 23.51 RIU⁻¹, respectively. These values indicate notable improvement over several reported SPR-based metal-ion sensors, highlighting the effectiveness of incorporating BaTiO₃ as a functional dielectric layer. Overall, the results confirm that the BK7/BaTiO₃/Au hybrid configuration offers enhanced plasmonic field confinement and superior sensing performance, making it a promising candidate for the rapid and highly accurate detection of hazardous metal ions in environmental and biochemical applications.