Study Of Novel Surface Plasmon Resonance Biosensor

Surface plasmon resonance（SPR）technology has been widely used in biosensing research,and plays an important role in food safety,medical diagnosis,and biometric identification because of its non-destructive,real-time monitoring and recording,rapidity,and high sensitivity for biomolecular level detection.The surface plasmon waves（SPW）excited by the Kretschmann configuration is usually very sensitive to the sensing medium,and when the SPW interacts with a small change in the refractive index of the sensing medium,the resonance curve changes significantly.However,conventional SPR biosensors are usually deficient in sensitivity（S）and detection accuracy（DA）,so it is necessary to investigate how to improve the performance of surface plasmon resonance biosensors.In recent years,two-dimensional materials and optical thin films have provided new possibilities for the development of SPR sensors.Numerous theoretical and experimental studies have shown that the addition of two-dimensional materials and optical thin films can significantly improve the performance of SPR biosensors.Therefore,this paper focuses on the role of 2D materials and new optical films in enhancing the performance of SPR biosensors and does the following research work:（1）A SPR biosensor based on metal-BiFeO₃-graphene structure was designed.In this structure,the high refractive index and low loss of BiFeO₃（BFO）optical film can not only enhance the sensitivity but also ensure high detection accuracy,and the addition of graphene helps to adsorb and identify biomolecules.Firstly,the influence of metal layer thickness on SPR effect is analyzed,and the optimal metal layer thickness is selected.Then,the performance of SPR biosensors with different structures were compared,and it was found that the performance of SPR biosensors with metal-BiFeO₃-graphene structure was better than other structures.Then,the influence of BFO thickness and graphene layers on the performance of SPR sensor is analyzed.The results show that the increase of BFO thickness can enhance the sensitivity of SPR biosensor significantly while ensuring the detection accuracy.Finally,the influence of the refractive index of the sensing medium on the SPR biosensor is studied.The results show that the SPR biosensor designed in this paper can work in a large detection range.（2）A new long-range surface plasmon resonance（LRSPR）sensor with low refractive index silica（Si O₂）film is proposed to improve the sensitivity and detection accuracy of the sensor.Adding a certain thickness of Si O₂ on the surface of aluminum layer as a dielectric buffer layer to excite LRSPW.Firstly,we compare the sensitivity and detection accuracy of the conventional SPR sensor with the proposed long-range SPR sensor.The results show that the sensitivity and detection accuracy of the proposed long-range SPR sensor are greatly improved compared with those of the conventional SPR sensor.Then we optimized the thickness of aluminum film and Si O₂ layer,and determined the optimal thickness of Si O₂ layer.Finally,we discussed the influence of TMDs layers on the sensing performance,and found that the sensitivity of LRSPR sensor modified by monolayer WS₂was 35.74 times higher than that of the conventional SPR sensor with monolayer Mo S₂.In addition,in terms of full width at half maximum（FWHM）and figure of merit（FOM）,the performance of LRSPR sensor based on monolayer TMDs are better than that based on multi-layer TMDs.