Research Of Fiber Surface Plasmon Resonance Sensor Based On Graphene And Metal Composites

At the metal-substrate interface,when the wave vector of the evanescent wave and the wave vector of the surface plasma wave are equal,the surface plasmon resonance(SPR)is excited.Based on the characteristics of SPR,the use of optical fiber as the sensing substrate makes the optical fiber SPR sensor come into being.The optical fiber SPR sensor is used to detect the refractive index of outside environment.The detection principle of the optical fiber SPR sensor is to use the SPR occurring at the interface between the metal and the fiber to detect the interaction between external molecules and the sensor surface.When the external molecular concentration information changes,it will cause the refractive index change near the fiber optic sensor,which will cause a certain change in the propagation constant around the sensor,and the resonance peak will be changed.By analyzing the changed in the spectral information,the detection of external molecules can be realized.The optical fiber sensor has high sensitivity,good flexibility,and simple operation,and has wide application prospects in the fields of biological analysis,chemical detection,and environmental monitoring.Optical fiber SPR sensors mostly use metal materials such as gold and silver as the sensing layer.In order to improve the performance of sensor,many methods have been proposed to improve the sensing material layer.Among them,compounding two-dimensional materials with metal can not only improve the sensitivity of the sensor,but also better adsorb external molecules,thereby achieving high-quality detection.The two-dimensional material graphene has a stable lattice structure,has a large specific surface area,superior spectral properties and excellent biocompatibility.Its appearance has brought gospel to researchers.Graphene and metal composite can not only serve as a protective layer of metal and act as an ideal molecular enrichment agent,but also enhance the interaction between light and matter.The charge transfer between graphene and metal canalso enhance the surrounding electric field and improve the sensitivity of the sensor,creating unlimited possibilities for the research of optical fiber SPR sensors.Based on the advantages of graphene and metal composites,and combining it with optical fiber sensing technology,this paper proposes a graphene composite gold film D-type plastic optical fiber sensor,and conducts in-depth experimental research on it.The specific work is as follows:(1)The principle,common structure and the research actuality of fiber SPR sensor are introduced.The application prospects of fiber SPR sensors in biological analysis,clinical applications,food safety and other fields are introduced.The advantages of graphene and metal composite materials were expounded.The research significance of graphene and metal composite materials D-type fiber sensors is discussed.(2)The preparation method of graphene composite gold film D-type plastic optical fiber sensor is introduced in detail,including the preparation process of D-type plastic optical fiber and the preparation process of graphene.The traditional transfer method of graphene is introduced,and a new kind of graphene transfer method — direct transfer is proposed.The feasibility of direct transfer of graphene is verified by Raman characterization and fluorescence detection experiments.(3)The experiment of graphene composite gold film D-type plastic optical fiber sensor was designed.It was verified by comparison experiments that graphene and metal composite materials are more beneficial to improve the sensitivity of the sensor than single metal.The designed sensor was applied to the field of bioanalysis,which implements dopamine detection and specific detection,and provides an attractive solution for biological analysis and clinical application.