Research Of Optical Fiber SPR Gas Sensor Based On Graphene

Gas spreads rapidly and is difficult to identify by human senses relative to the liquid and solid.So,inflammable and explosive gas detection is effective to avoid and prevent accident happening.With the development of science and technology,the demand of gas concentration detection is higher and higher,detection limit is lower and lower,sensitivity is higher and higher in the production and life.In the numerous optical fiber sensing structures,optical 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,on-line real-time measurement,small size,and suitable for long distance measurement,etc.Optical fiber SPR sensors combined with gas sensitive material in gas concentration measurement has become a hotspot of gas sensor.Graphene,which was discovered in 2004 by the 2010 Nobel Prize winner Geim and Novoselov,is a kind of 2D material arranged into a honeycomb structure by single carbon atoms.Graphene not only has excellent photoelectric properties,but also has the ability of adsorption molecules and is sensitive to environment change,even the single gas molecules.This topic put forward a kind of optical fiber SPR gas sensor based on graphene,which is graphene combined with optical fiber SPR sensor,grapheme-optical fiber SPR sensor.Refractive index and adsorption characteristics of grapheme-optical fiber sensor have been analyzed,production method of sensor has been researched and the experimental system was designed and tested,the work of the following contents have completed:(1)Overview of the development of optical fiber SPR sensor technology and research status,and the present situation of the application of graphene in the field of optical fiber gas sensor,mainly using graphene adsorption characteristics.On the basis of these,the research content and research significance of this topic were puts forward.(2)Analyzing the principle and properties of optical fiber SPR sensor and establish four layer membrane structure optical fiber SPR sensor model.Exploring optical properties of grapheme and gas adsorption performance,and simulation calculation graphene refractive index variation due to molecules adsorbed.Finally put forward the sensor structure,simulate and optimize sensor structure by the MATLAB.(3)Exploring preparation method of silver film on optical fiber SPR sensing probe by chemical method,which greatly simplifies coating method and reduces cost,and verify the quality and optimal thickness of silver film by simple experiments at the same time.Then,study the preparation method of graphene,and transfer method of graphene to complete graphene-optical fiber SPR sensing probe.(4)Verifing graphene enhancement optical fiber SPR sensor refractive index and gas sensing characteristics,the building method and experimental steps of the experiment system were introduced in this paper.Good experimental results have been got,the sensitivity of graphene-optical fiber SPR sensor is 3898 nm/RIU in 1.333?1.374 and standard deviation of refractive index single point measurement is less than 10-3,which is higher than the sensor without graphene 2643nm/RIU.The concentration of ammonia gas was measured by the graphene-fiber SPR sensor,the minimum ammonia concentration can be detected to 3ppm by the graphene-optical fiber SPR sensor,maximum sensitivity up to 333pm/ppm.And the feasibility of measuring microscale gas by graphene-fiber SPR sensor is verified.