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Research On Optical Fiber SPR Sensor For Refractive Index Measurement With Temperature Compensation

Posted on:2016-03-04Degree:MasterType:Thesis
Country:ChinaCandidate:Z Q DengFull Text:PDF
GTID:2428330542989566Subject:Detection Technology and Automation
Abstract/Summary:PDF Full Text Request
Liquid refractive index mainly depends on its molarity.Nevertheless,variation of liquid temperature also has effect on liquid refractive index.With the rapid development of science technology,the accuracy of liquid refractive index measurement is much higher than before.The resolution of liquid refractive index measurement has reached higher than 10-6RIU.1?fluctuation of liquid temperature will lead to 10-5RIU variation to liquid refractive index,which indicates that temperature variation has significant influence on refractive index measurement.Therefore,a liquid refractive index sensor with temperature compensation is indispensable for high accuracy refractive index measurement.Fiber Surface Plasmon Resonance(SPR)sensor has been widely applied to biomolecule detection and liquid refractive index measurement for its high sensitivity,label-free,pollution-free and on-line real-time measurement.However,most of researches about fiber SPR sensor are focus on single parameter measurement,particularly liquid refractive index.Fiber SPR sensors for temperature measurement have been proposed before,but the sensitivity of those temperature sensors is not high enough.Combining fiber SPR with Fiber Bragg Grating(FBG),a fiber SPR sensor based on Multi-mode Fiber-Fiber Bragg Grating-Multi-mode Fiber(MFM)structure has been proposed in this thesis.This proposed sensor is named as "fiber MFM-SPR sensor" for short,and it can detect temperature while measuring liquid refractive index.The main contents in this thesis are listed as follows:Firstly,different types of fiber liquid refractive index sensor are introduced,as well as their research status.Especially the origins of the fiber SPR sensor and its research status at home and abroad are reviewed.As the fiber SPR sensor is sensitive to the temperature,a fiber SPR refractive index sensor with temperature compensation is proposed.Secondly,the sensing principle and property of fiber SPR sensor are discussed.Based on the principle of surface plasmon resonance,a three-layer media SPR model is built,which is applied to build the fiber SPR model after modifying.The structure parameters of fiber SPR sensor,including sensing metal type,thickness of metal layer and sensing length are optimized by MATLAB.Thirdly,the fiber MFM-SPR sensor is designed and fabricated,and the fiber MFM-SPR sensing system is established.Two basic experiments are conducted to confirm that the fiber MFM-SPR sensor can measure liquid refractive and detect temperature respectively.According to the optimized parameters through simulation,the fiber MFM-SPR sensor is fabricated with chemical coating method.Fourth,liquid refractive index measurement experiment and temperature detection experiment of fiber MFM-SPR sensor are conducted.In the liquid refractive index range of 1.33?1.38,the sensitivity is 3159.4nm/RIU.The relative standard deviation(RSD)of single-point refractive index measurement is within 10"3.In the temperature range of 33 ??50?,the temperature sensitivity of fiber MFM-SPR sensor is 10pm/? with good accuracy and repeatability.The proposed fiber MFM-SPR sensor in this thesis improves the accuracy of liquid refractive index measurement by introducing FBG to serve the purpose of temperature compensation.The chemical method is used for coating fiber SPR sensor for the first time,which simplifies the coating process and reduces cost.However,the repeatability of refractive index measurement of fiber MFM-SPR sensor is not favorable enough.Consequently,the antioxidant and fastness of metal layer should be improved,and the packaging process of the sensor needs a further research.
Keywords/Search Tags:Optical Fiber SPR Sensor, Fiber Bragg Grating, Refractive Index Measurement, Temperature Compensation
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