Swift detection of heavy metals in water by encoded graphene–gold-metasurface sensor

This paper presents a graphene–gold-metasurface sensor designed for rapid and precise detection of heavy metals, particularly Cu²⁺ and Mg²⁺ ions, in water samples. By employing COMSOL simulations, the sensor’s performance across various cases was comprehensively analyzed. The sensor demonstrates an optimized sensitivity of 1140 GHz/RIU for Cu²⁺ detection and 1149 GHz/RIU for Mg²⁺ detection. Furthermore, this sensor achieves minimum figure of merit (FOM) of 2.781 RIU⁻¹ and 2.855 RIU⁻¹ for Cu²⁺and Mg²⁺ detection, respectively, showcasing its superior performance in sensing these metal ions. Also the highest quality factors (Q factors) of 11.244 for Cu²⁺ detection and Q factor 11.247 for Mg²⁺ detection are attained. The proposed sensor structure additionally demonstrates very low detection limits- which is 0.466 for Cu²⁺ and 0.485 for Mg²⁺ detection-and this implies it can detect trace amounts without any difficulty. The excellent promising features of this sensor position it as a self directed candidate for detection of Cu²⁺ and Mg²⁺ ions with high accuracy and sensitivity. These solid applications act as the gateway to the monitoring of environmental cleanliness among other applications. Additionally,the proposed sensor can also be used as a 2-bit encoder.