Study On Sensing Characteristics Of Metal/metal-Oxide Coated Microfiber

With the rapid development of industrialization,it is very necessary to monitor the flammable,explosive,toxic,harmful and other dangerous environment.Metal and metal oxides have the advantages of simple preparation,low cost and can be safely and effectively used in high pressure,high temperature,corrosion or other harsh environments.Therefore,metal and metal oxide sensors have been widely used in various industries and fields.The structure not only has the advantages of small volume,high sensitivity and anti-electromagnetic interference,but also can improve the sensitivity and selectivity of the sensor.The design of optical fiber sensor structure based on metal coating becomes the focus of research.In this paper,metal material and optical fiber sensor are combined to enhance the sensitivity of optical fiber sensor to gas and refractive index.First of all,Fe₂O₃ nanotubes and WO₃ nanorods are prepared by a simple hydrothermal method.In the experiment,we can control the quality of reactants,the temperature,the length of reaction time and the pH value of the mixed solution to prepare oxide nanomaterials with different morphology and different components.The composition analysis and morphology observation of the prepared metal oxide materials are carried out by means of the scanning electron microscope and X-ray diffractometer.Secondly,the optical fiber sensor is fabricated by flame melting taper technology,and the metal oxide material is coated on the surface of the sensor to detect the gas with a different concentration.The experimental results show that the structure of the Fe₂O₃ coated sensor has good adsorption performance for ammonia molecules,which is 11.80 times more sensitive than that of the sensor without Fe₂O₃ coated.Compared with the detection of methanol,ethanol,acetone and other gases,the sensor has obvious selectivity for ammonia gas.The wavelength shift of the optical fiber structure coated with WO₃ nanorods is 54.10 times that of the structure without WO₃ nanorods.The sensor has good recoverability,selectivity and repeatability.Therefore,the combination of metal oxide material and optical fiber sensor structure can greatly improve the response characteristics of the sensor to ammonia gas,and enhance the sensitivity and selectivity of the sensor.Finally,the refractive index response characteristics of the optical fiber SPR sensor based on metal coating are simulated by the finite element method,optimize the parameters and improve the detection sensitivity of the sensor.The simulation results show that based on the structure of the polished PCF-SPR sensor coated with gold and WO₃ material,the maximum sensitivity of the sensor can reach 11381.67 nm/RIU.The maximum sensitivity of the optical fiber SPR refractive index sensor based on the elliptical analysis hole is 6163.17 nm/RIU.In conclusion,the combination of microstructure optical fiber and metal material can produce an optical fiber gas sensor with high sensitivity and selectivity.The optical fiber SPR refractive index sensor model based on the finite element method provides a reliable theoretical support for experimental research.