Research On Fiber Optic PH Sensor Based On F-P Interference And SPR Principle

pH is an important parameter in biomedicine,environment,chemistry and agricultural production.At present,p H measurement methods include indicator method,p H test strip method,p H meter method,electrode method,etc.,the above methods have low accuracy,large error,environmental pollution,long detection time,expensive equipment and other problems.Therefore,there is an urgent need for p H monitoring technology with high sensitivity,good biocompatibility,fast response speed and low cost.In recent years,p H-sensitive gels have greatly improved the sensitivity and response speed of p H detection due to their unique sensitizing effect.In this paper,p H-sensitive hydrogels are combined with fiber optic sensors to design and produce three different structures of fiber optic p H sensors,the main contents of which are.Firstly,the research status of optical fiber p H sensors based on p H-sensitive gels was extensively investigated.The working principle of hydrogel,the principle of optical fiber F-P sensor,and the sensitization principle of optical cursor effect based on parallel F-P cavity structure are introduced.Secondly,the p H sensing characteristics of optical fiber based on the F-P interference principle are studied,and the influence of gel cavity length on the interference spectrum is simulated and analyzed by using the gel as the F-P interference cavity,and the relationship between cavity length and end face reflectance and interference spectrum is studied.On this basis,the F-P cavity sensor of parallel structure is designed,and the sensitization characteristics of the structure are analyzed and calculated.Thirdly,a fiber p H sensor based on the F-P interference principle was made,the sensing structure was designed,the gel film was prepared,and an experimental system was established to verify the sensitivity and stability of the sensor.On this basis,a parallel double F-P cavity structure optical fiber p H sensor is designed,and an experimental system is established to test the sensitization performance of the sensor by the vernier effect.Finally,the p H sensing characteristics of optical fiber based on SPR principle are studied,and the effects of metal film type,thickness and refractive index on sensor performance are simulated and analyzed.The structure of the "MSM" sensor was prepared,and the magnetron sputtering technology was used to coat the coating,and an experimental system was established to verify the possibility of p H value change of the sensor.In this paper,the fiber optic p H sensor prepared based on the F-P interference principle and SPR principle has the advantages of high sensitivity,simple structure and strong anti-interference ability,which provides an experimental basis for the development of fiber optic pH sensor.