High Sensitivity Refractive Index Biosensor Based On Two Dimensional Materials

A lot of biosensors have been researched,with the development of science and business.In these biosensors,optical biosensor has received widespread attention owing to it has high sensitivity,label-free,high detection speed and so on advantages.Surface plasma resonance?SPR?biosensor is one of the optical biosensors,which has faster and more comprehensive development.However,metal which has negative permittivity has been used as excitation element in SPR biosensor,which can enhance the energy loss and reduce the performance of biosensor.A new type of two-dimensional material such as graphene,molybdenum disulfide?MoS₂?,etc.have been used in enhancing the performance of biosensor.On the other hand,to compensate for SPR biosensor limitations,one-dimensional photonic crystal?1D-PC?which energy loss is negligible have been employed to design the Bloch surface wave?BSW?biosensor by researchers.In the study of this thesis,the main research is using the characteristic of two-dimensional material to enhance the performance of SPR biosensor.Besides,high-performance BSW biosensor has been designed for using two-dimensional material and 1D-PC.The main research results are as following:?1?A prism coupling SPR biosensor has been designed,which using two layers of gold and MoS₂ compose waveguide structure to excite SPR phenomenon.Moreover,graphene has been added in the biosensor to enhance the performance and protect the structure of biosensor.In this work,the number of MoS₂ layers and the number of graphene layers have been discussed for the influence of reflectivity curve of biosensor.Through optimization,the greatest sensitivity of biosensor can reach182^o/RIU in four MoS₂ layers and 1 graphene layer,which is higher than the sensitivity of traditional SPR biosensor.This result was published in IEEE Photonics Journal.?2?In the study of the photonic crystal biosensor,it was found that the reflectivity curve of the sensor appeared a peak which was suitable for the detection of biomolecules before the critical angle.So this work has designed a biosensor with1D-PC and graphene/MoS₂.In this structure,we discussed the effect of photonic crystal cycle on reflectivity curve,discussed the influence of the number of graphene/MoS₂ layers on reflectivity curve,and discussed the influence of prism with different refractive index on the performance of biosensor.The conclusion is that MoS₂ can improve the sensitivity of biosensor better than graphene,and the smaller the refractive index of prism,the greater the sensitivity of biosensor.?3?In this work,TiO₂ and SiO₂ have been used to compose 1D-PC,while also adding a few layer graphene designed a high sensitivity BSW biosensor.The stimulation of BSW need to introduce a defect layer in 1D-PC,after optimization the final thickness of the defect layer set to 120nm.Through optimization,the intensity sensitivity of the biosensor can obtain the maximum value of 35000/RIU in two layers of graphene.This value is higher at the order of magnitude than the traditional SPR biosensor and the traditional BSW biosensor.This work was published on IEEE Sensors Journal.