Enhanced Goos-Hänchen Shift of SPR Sensor with TMDCs and Doped PANI/Chitosan Composites for Heavy Metal Ions Detection in Aquatic Environment

Abstract

Abstract A novel surface plasmon resonance (SPR) sensor with transition metal dichalcogenides (TMDCs) and polyaniline (PANI)/chitosan composite for detection of heavy metal ions in an aquatic environment is proposed and analyzed. The Goos-Hänchen (GH) shift is employed as an important method for analyzing the performance of the SPR sensor. It is theoretically shown that the GH shift can be significantly enhanced in the SPR structure silver (Ag) coated with a TMDCs and PANI/CS heterostructure. When the incident light wavelength is 632.8nm, the refractive index of Cu2+ ion is 1.3516. Through comparison and optimization analysis, when the thickness of MoSe2 and PANI/chitosan is monolayer and 123 nm, respectively, the maximum GH shift is -2067λ at resonance angle 69.19°. When different Cu2+ ion concentrations are added into the sample layer, the refractive index of the sample and GH shift of the SPR sensor will change. The maximum sensitivity of 2.425×106 λ/RIU is obtained by Ag-WSe2-PANI/chitosan structure, which is 463.42 times higher than the traditional SPR Ag film and 112.84 times higher than Ag-PANI/chitosan structure. The discovery of the Kretschmann structure SPR sensor with 2D material provides a new development direction for the detection of heavy metal ions in an aquatic environment.