Research On SPR Sensor Based On Two Dimensional Materials

The Surface Plasmons as a special physical phenomenon,is a kind of a longitudinal electromagnetic wave.There is a strong local characteristic of the surface plasmons,which is very sensitive to the changes of the environment.Based on this characteristic,Surface Plasmons Resonance?SPR?sensing detection technology has been discovered and studied by people.And SPRsensing detection technology has been widely applied in biological sensing,chemical analysis,drug research and development,food safety,medical diagnosis and so on.The Surface Plasmons Resonance sensor is a sensing structure based on the principle of surface plasmon resonance.SPR sensor with high sensitivity and high quality has been the goal pursued by people.The two-dimensional?2D?materials,such as graphene,have the advantages of high response rate,high electron mobility,excellent absorption and emission characteristics.After discovered,two dimensional materials have aroused widespread concern and provided infinite possibilities for the development of SPR sensors.Theoretical and experimental studies have demonstrated that two-dimensional materials used in SPR sensors can greatly improve the performance of SPR sensors.Based on the superiority of dimensional materials in SPR sensor and the wide application of SPR sensors,Graphene-WS₂-Au-Ag and AgNF/BP/ZnO SPR sensor are designed in theory,and we simulate and analyze the influence of its composition on the performance of SPR sensor,such as size,structure and so on.The details of the work are as follows:?1?The design of SPR sensor based on Graphene-WS₂-Au-Ag.On the basis of bimetallic layer,we use graphene,WS₂ and MoS₂ three kinds of two-dimensional materials to improve the performance of bimetallic sensing structure.The final calculation results show that compared with graphene and MoS₂,the sensitivity of SPR sensor with WS₂ increases greatly and the best number layer of WS₂ is 1.On this basis,the graphene layer is covered,and the trend of sensitivity is to rise first and then drop with the increasing of the number of graphene,but the FWHM will rise.When the number of graphene is 1,the sensitivity?182.5Deg/RIU?will be higher than the pure Au sensor,and the FWHM?5.4 Deg?is obviously lower than the pure Au sensor.When the number of graphene is 4,the sensitivity can reach the maximum?192.5 Deg/RIU?,which is obviously higher than the sensitivity of the SPR sensor based on pure Ag film.Compared with the pure Au layer,the FWHM?7.3 Deg?of the SPR sensor at this time is slightly smaller.In addition,the sensitivity and FWHM of other composite structures of bimetallic layer are also analyzed.It is concluded that SPR sensor with high sensitivity and high resolution can be achieved with the best thickness range of silver and gold is 26-32 nm and 11-16 nm respectively.?2?The sensitivity of the SPR sensor with Ag is low and Ag is extremely easy to be oxidized.In view of the defects,a small layer of BP and the Zinc Oxide?ZnO?layer are used to improve the sensitivity of the SPR sensor.The relationship between sensitivity and thicknesses of Ag layer ZnO is calculated and analyzed.The results show,the sensitivity of SPR sensor with AgNF/BP/ZnO hybrid nanostructure can reach its maximum value?370Deg/RIU?when the thicknesses of AgNF,BP,ZnO are respectively 48,5 and 11 nm.And we find that the enhanced factors of sensitivity are 3.2,2.8,2.04,1.31 compared with SPR sensors based on AgNF only,AgNF/ZnO,AgNF/BP and AgNF/BP/WSe₂ respectively.