Detection And Analysis Of Mixed Liquid Components Based On SPR Technology

Nowadays,environmental issues are paid attention to.The safety of drinking water is the top priority.Excessive heavy metal ions in drinking water will cause serious harm to human health.Therefore,the detection and analysis of the composition and concentration of drinking water is very important.The analysis method based on surface plasmon resonance（SPR）technology has great advantages in the field of liquid analysis because it does not require marking and can be measured on site.Aiming at the limitation that traditional SPR equipment can only detect and analyze the concentration of one component,and the expensive cost of using antigen and antibody to achieve multiple detection,this paper establishes a scheme for measuring the concentration of the mixed solution component based on SPR technology.Three aspects of theoretical research,software simulation and experiment have conducted in-depth research on the SPR phenomenon,and the feasibility of the scheme has been proved through experiments,and finally the measurement and analysis of the concentration of the mixed solution has been achieved.In terms of theoretical research,this paper starts with the theory of electromagnetic wave transmission and studies the interaction between light and metal media.The principle of SPR phenomenon is that the constrained electrons on the metal surface resonate due to the absorption of light energy.And summarizes the three conditions that produce SPR phenomenon:total reflection,suitable metal interface and P polarized light.And on this basis,the SPR reflectivity model is established.Furthermore,based on the theory of the electronic cloud conductor model,a refractive index model of a ternary mixed solution is obtained.This model corresponds the composition and concentration of the mixed solution to the macroscopic parameter of refractive index.And the analytical calculation method based on the refractive index-concentration model is established.In terms of software simulation,this paper validates the reflectivity model of the prism SPR sensor through Matlab simulation.In addition,the factors that affect the SPR phenomenon（resonance angle and absorption peak depth）are also studied:the wavelength of the incident light and the thickness of the metal film only affect the depth of the SPR absorption peak,and the material of the SPR sensor and the concentration of the sample will significantly affect the position of the resonance angle.The best SPR sensor structure is calculated by Matlab software:BK7 glass and Ag film with a thickness of 46nm.Finally,the relationship between the refractive index of the sample and the resonance angle of the SPR is analyzed by simulation.When the refractive index of the sample changes in a small range,the resonance angle of the SPR changes linearly.In terms of experiments,a space optical path system was built,and experiments were conducted with aluminum ionsAl^3（10）and copper ionsCu^2（10）as the components to be measured.The measurement accuracy of the system is10^-5～10^-4RUI.When the sample concentration changes in a small range,the resonance angle changes linearly with a linearity of 0.9969.After measurement and analysis,the relative error of the concentration of the mixed solution is at least 0.87%,and with the increase of the concentration,the relative error of the maximum error reaches 3.71%,which verifies the feasibility of the scheme proposed in this paper.