Heavy Metal Detection Based On Optical Fiber SPR

Heavy metals not only pollute the environment,but also harm human health.In recent years,with the development of society,heavy metal pollution has become an urgent problem to be solved.Therefore,detection of heavy metal ions has become a focus of scientific research.Optical fiber surface plasmon resonance(SPR)sensors have attracted extensive attention in recent years because of their high detection sensitivity and real-time monitoring of samples.In this paper,lead ion detection based on optical fiber SPR sensor is studied.The specific work is as follows :Firstly,the principle of surface plasmon resonance and the optical properties of metal for surface plasmon resonance are introduced,as well as the development of SPR sensing technology based on surface plasmon and SPR sensing technology.Then the harm of heavy metals and detection methods of heavy metals are described.The application and development of fiber optical SPR sensing technology in detecting heavy metal ions and the main factors affecting the sensitivity of fiber optic SPR sensing in the detection process are mainly introduced.The main factors affecting the sensitivity of the sensor are the material and thickness of the film coated on the surface of the optical fiber,and the morphology and size of the metal particles.Then we use FDTD simulation analysis of metal nanoparticles structure on the sensitivity of optical fiber SPR sensor.Secondly,the optical fiber SPR sensor modified with gold,platinum and Palladium nanorods is theoretically studied by FDTD.The results show that the sensitivity of the optical fiber SPR sensor sensitized by gold nanorods with a radius of 8 nm and a length of 40 nm is up to 3160.0 nm/RIU.The refractive index sensitivity can reach 6070.0nm/RIU when modified by platinum nanorods with radius of 5 nm and length of 80 nm.The refractive index sensitivity of the modified pd nanorods with radius of 8 nm and length of 60 nm can reach 6210.0 nm/RIU.The physical mechanism of enhanced sensitivity of sensor modified by nanoparticles is analyzed theoretically.Finally,two kinds of optical fiber SPR sensors used to detect the concentration of lead ions were designed and prepared,and an experimental system was built to detect the actual detection experiments.The experimental results show that the optical fiber SPR sensor without gold nanoparticles modification has a detection sensitivity of3485.8 nm/mol,while the optical fiber SPR sensor with gold nanoparticles modification has a higher detection sensitivity of 4623.4 nm/mol for lead ions.The mechanism of improving sensor sensitivity after gold nanoparticle modification is analyzed theoretically.