High Sensitivity Surface Wave Sensor Based On Two-dimensional Material And Its Application In Heavy Metal Detection

In recent years,researches on various types of biosensors have been carried out in order to meet the practical application needs of the scientific research and commercial markets.Among them,the research of optical biosensors has received extensive attention.Compared with other types of biosensors,optical biosensors have the advantages of fast response,high sensitivity,and high stability.At present,surface plasmon resonance(SPR)biosensor based on Kretschmann structure is widely used in different applications such as life science,electrochemistry,environmental safety and medical diagnosis due to its label-free and real-time detection characteristics.Surface plasmon polaritons(SPP)presented on the surface of the metal medium forms a surface plasmon wave(SPW)by the coupling prism and the excitation of the polarized beam,and this surface wave is extremely sensitive to changes in the refractive index of the external environment.The change in the refractive index of the sensing layer can ultimately be translated into a significant change in the optical quantity of the reflected spectrum to detect the analytes.The traditional SPR biosensor based on precious metals has poor biomolecular binding ability,which greatly limits the sensitivity and figure of merit.Therefore,designing a new type of highly sensitive biosensor has become an important issue.With the rapid development of materials science,the method to enhance the sensitivity of biosensors is usually to combine sensing technology with functional two-dimensional materials such as Graphene,Black phosphorus,and transition metal compounds(TMDCs)and so on.Secondly,strong coupling between modes of different structures can also improve sensitivity.The combination of the two methods offers more possibilities for the development of biosensors.The paper mainly studies the sensitivity performance of a series of sensor chips composed of new two-dimensional materials and different mode structures.The research results are as follows:(1)An SPR refractive index biosensor based on topological insulator,bismuth telluride(Bi₂Te₃)is designed.Under the angle modulation and wavelength modulation,by optimizing the thickness of Bi₂Te₃ to select the optimum thickness value,the angular sensitivity and wavelength sensitivity of the sensor can be both improved,and the highest angular sensitivity can reach 175°/RIU.Related research results are published in Results in physics.(2)A special waveguide mode,a kind of graphene-based lossy mode resonance(LMR)biosensor,is designed.Among them,the upper surface of graphene covers the cytop layer,a low-loss fluoropolymer that is easy to form a film.The larger surface area of graphene can enhance the adsorption with biomolecules,improve the detection sensitivity and quality factor.And the resonance intensity under different modes can be changed by selecting appropriate optimized value of graphene thickness.Compared with SPR sensors,this kind of LMR biosensor can excite resonance in the transverse electric(TE)and transverse magnetic(TM)modes,and the figure of merit is greatly improved,nearly ten times that of ordinary SPR sensor.The results is published in Plasmonics.(3)An SPR biosensor based on two-dimensional material of germanium selenide(Ge Se)semiconductor is proposed.By spin coating different layers of selenium telluride on gold sheets,the detection sensitivity of ethylene glycol solution with different refractive index gradually increases,and then it goes down.The quality factor is 14.37RIU^-1,and the best detection sensitivity is 3581nm/RIU when the coating is rotated four times,which improves nearly 80%on the basis of the traditional gold-based SPR sensor.At the same time,the sensitivity and resolution of the sensor for metal lead ion detection are greatly improved.The research is published in Nanophotonics.