The Research Of Optical Fiber And Sers Sensors Based On Several Two-dimensional Materials Enhancement Characteristics

The two-dimensional material was presented with the successful separation of graphene from the single-atom layer by the Geim team at the University of Manchester in 2004.The outstanding characteristic of graphene is single atomic layer two-dimensional honeycomb lattice structure of the carbon material,high carrier mobility(10⁶ cm²V^-1s^-1)and linear spectrum,high strength and high specific surface area(2630 m²g^-1),in both theoretical research and application fields,graphene has aroused people's great interest.Graphene oxide?GO?is the natural crystal graphite with strong oxidizer in oxidation stripping,a material which introduce a large number of oxygen containing functional groups on the edge of the surface of graphene structure.And graphene oxide has excellent biocompatibility and chemical stability.As a kind of graphene materials,molybdenum disulphide has obvious similarities with graphene,consists of three atomic layer,each S atomic bonding with 3 Mo atoms,each Mo atoms and 6 S atomic bonding,also has a large specific surface area,in the fields of nano-electronics,photoelectric materials,energy collection and other fields,it shows great potential of application.Compare with graphene,MoS₂ can be easier bio-modifed,which make it more widely used in biosensor.MoS₂,possessing the advantages of high light transmission,chemical stability,biomolecular affnity and low-temperature synthesis.This paper is based on the unique sensing properties of molybdenum disulfide,graphene and graphene oxide,we have fabricated evanescent wave absorption sensor based on U-bent tapered multimode fiber covered by MoS₂,LSPR sensor based on U-bent plastic optical fibre?U-POF?with PVA,AgNPs,graphene and a layer of discontinuous Ag film and?SERS?substrate based on graphene oxide/silver nanoparticles/copper film covered silicon pyramid arrays.?1?In this work,we presented a novel evanescent wave absorption sensor based on U-bent tapered multimode fiber covered by molybdenum disulfde?MoS₂?film?MoS₂@TU fiber EWA sensor?.The multimode fiber was manufactured by the fused tapered fiber machine,and then heated using a butane candle flame and bent into a U-bent structure.MoS₂ was grown on the fiber directly by thermally decomposing the precursor of?NH₄?₂MoS₄.We have demonstrated that the MoS₂ can be applied in the fled of EWA sensor,and the EWA sensor based on U-bent tapered multimode fiber?TU fiber?possessed higher sensitivity than that based on U-bent fiber.The sensitivity??A/?C?of the developed EWA sensor is 0.34 in detection of ethanol solution.It shows good sensitivity,linearity,repeatability and stability in detection.And the developed EWA sensor also shows good performance in detection of the adenosine solution,this work shows that the developed EWA sensor may have promising applications in biosensing.?2?In this work,we have presented a novel local surface plasmon resonance?LSPR?sensor based on the U-bent plastic optical fiber?U-POF?.Firstly,a layer of discontinuous silver?Ag?thin film was deposited on the U-POF and then the Ag film was covered by a layer of cladding synthesized by polyvinyl alcohol?PVA?,graphene and silver nanoparticles forming the PVA/G/AgNPs@Ag film.The normalized transmittance spectrum of the LSPR sensor have been collected in a range of the refractive index?RI?from 1.330 to 1.3657 in ethanol solution,and 700.3 nm/RIU sensitivity of the developed LSPR sensor has been demonstrated.By experiments,we demonstrated that the graphene could improve the sensitivity of the LSPR sensor and delay the oxidation process of the AgNPs effectively to keep the stability of the LSPR sensor.The LSPR sensor also exhibited good sensitivity and linearity in the detection of glucose solutions.This work shows that the developed LSPR sensor may have promising applications in biosensing.?3?We present a novel surface-enhanced Raman scattering?SERS?substrate based on grapheneoxide/silvernanoparticles/copperfilmcoveredsiliconpyramidarrays?GO/AgNPs/PCu@Si?by a low-cost and simple method.Graphene oxide?GO?has superior bio-compatibility and chemical stability due to the active oxygen sites,which can notably enhance the graphene-metal/molecule binding,depress the fluorescence background,and increase the Raman/fluorescence signal-to-noise ratio.The GO/AgNPs/PCu@Si substrate presents high sensitivity,good homogeneity and well stability with R6G molecules as a probe.The detected concentration of Rhodamine 6G?R6G?is as low as 10^-1515 M.These sensitive SERS behaviors are also confirmed in theory via a commercial COMSOL software,the electric feld enhancement is not only formed between the AgNPs,but also formed between the AgNPs and Cu film.And the GO/AgNPs/PCu@Si substrates also present good property on practical application for the detection of methylene blue?MB?and crystal violet?CV?.This work may offer a novel and practical method to facilitate the SERS applications in areas of medicine,food safety and biotechnology.