Preparation And Sensing Properties Research Of Polymer Micro/nanofiber

With the rapid development of optical fiber sensing technology and micro/nanometer technology,it is promising to develop optical fiber sensor with more miniature,functional and compact by combining this two technologies.This paper focuses on the preparation of polymer micro/nanometer fibers and research on their refractive index sensing properties.The polymer micro/nanofiber and palladium nanoparticles was combined to sense the hydrogen concentration based on the specific absorption characteristics of palladium-hydrogen.This composite polymer micro/nanofiber hydrogen sensor has the advantages of low cost,high sensitivity,small size,convenient preparation and potential practical value compared with other method by coating Pd film on the surface of common optical fiber.The main contents are listed as follows:(1)The domestic and international development of polymer micro/nanofiber concluded and reviewed.In addition,the advantages and disadvantages of polymer micro/nanometer fiber,as well as the different kinds of preparation methods of polymer micro/nanofiber were analyzed and compared with that of ordinary fiber.Finally,the prepared polymer micro/nanometer fiber has been demonstrated sensing the refractive index of surrounding environment.(2)The advantages and disadvantages of several kinds of fiber coupling methods,and the factors have been concluded and analyzed.The corresponding affect on the coupling efficiency of the evanescent wave were analyzed.Based on the model analysis of single mode fiber cones and polymer micro/nanometer fiber,the sensing mechanism of polymer micro/nanometer fiber was described.(3)A high sensitive refractive index sensor based on composite fiber was designed,which was mainly comprised by the polymer micro/nanometer fiber fabricated by directly drawing method from poly(methyl methacrylate)colloid.Through the evanescent wave coupling method,the whole sensing system was built by means of micro-manipulation under microscope.The dip wavelength in the measured spectrum caused by the models interference shifted obviously when the surrounding refractive index changed.The approximate linear relationship between surrounding refractive index and dip wavelength shift was obtained experimentally.The measurement sensitivity have been demonstrated up to 1490 nm/RIU with the surrounding refractive index ranging from 1.3333 to 1.3403 by using the polymer micro/nanometer fiber with a diameter of 6.6?m.Finally,the refractive index sensing properties of PMMA micro/nanometer fiber with different diameters,as well as that of the PMMA micro/nanometer fiber and single mode fiber taper were compared.(4)The experimental platform for sensing hydrogen concentration was designed and built using the polymer micro/nanometer fiber embedded with palladium nanoparticles.The measurement sensitivity and the resolution were demonstrated as 4.5×10-4nm/ppm and 44.44ppm respectively,with the hydrogen concentration ranging from 0%to 1%by using the doped PMMA micro/nanometer fiber with a sensing length and diameter of 473?m and 28?m respectively.Finally,the sensing length impact of the doping palladium nanoparticles on the hydrogen sensing perfromance has been explored.the hydrogen sensing properties of the palladium nanoparticles doped and pure PMMA micro/nanometer fiber were compared.