Research On Avian Influenza Sensor Based On Long-period Fiber Grating At The Inflection Point Of Dispersion

Since its inception,fiber gratings have attracted the attention of many scientific researchers and have been widely used in the measurement of various physical quantities(refractive index,temperature,strain,bending,vibration,etc.).With the deepening of research,it has also obtained further applications in the field of biosensing.Compared with traditional electrochemical biosensors,fiber grating biosensors have the advantages of miniaturization,compactness,high sensitivity,label-free,anti-electromagnetic interference,and remote monitoring.Among the many fiber grating biosensors,biosensors based on dispersion turning point long-period fiber gratings(DTP-LPFG)are often used for the detection of molecular biomolecules due to their excellent sensing properties.In this paper,based on DTP-LPFG surface-modified nano-titania particles,a bird flu biosensor with high sensitivity and high specificity will be fabricated.The main research contents are as follows:(1)The basic structure and mode coupling theory of fiber grating are introduced.Based on the principle of optical fiber three-layer film waveguide,the phase matching conditions of DTP-LPFG are introduced,and the characteristics of core and cladding mode coupling are analyzed in detail,and then the sensing characteristics of DTP-LPFG such as refractive index,temperature are studied.(2)Research on avian influenza biosensor based on polyacrylic acid(PAA)modified nano-titanium dioxide modified DTP-LPFG.The nanometer titanium dioxide is modified to the surface of DTP-LPFG by covalent bonding;then the avian influenza antibody molecule is used as a specific recognition unit to prepare a biosensor to achieve high-sensitivity detection of avian influenza antigens.The experimental results show that after surface modification,the refractive index sensitivity of DTP-LPFG is increased by 1.05 times,reaching1063.44nm/RIU.It is further applied to the detection of avian influenza.The experimental results show that the detection limit of the avian influenza biosensor is2.7ng/m L,the detection saturation point is 50?g/m L,and the dissociation coefficient and affinity coefficient for AIV are respectively It is 2.80×10^-9M and 3.57×10⁸M^-1.(3)Avian influenza biosensor based on graphene oxide(GO)/PAA modified nano-titanium dioxide modified DTP-LPFG.The GO/PAA is used to modify the nanometer titanium dioxide particles and modified with DTP-LPFG,and then the avian influenza virus biosensor with good specificity is prepared after biofunctionalization.The experimental results show that after surface modification,the refractive index sensitivity of DTP-LPFG is increased by 1.27 times,reaching 1144.67nm/RIU.The results of avian influenza detection experiments show that the sensor has good specificity for avian influenza molecules,the detection limit is 3.4ng/m L,and the detection saturation concentration is 50?g/m L.The Langmuir model is used to analyze the experimental data and calculate the avian influenza The dissociation coefficient of the biosensor for avian influenza antigen molecules is 5.85×10^-9M,and the affinity coefficient is 1.71×10⁸M^-1.Since each modification process of the optical fiber surface is a covalent bonding method,the sensor structure is stable and has further research value.