Graphene Biosensors Based On Surface Plasmon Resonance

On the basis of surface plasmon resonance(SPR), SPR biosensor is widely used in biochemical engineering, clinical diagnosis, pharmaceutical engineering, food security, environmental inspection, because it has the advantages of high sensitivity detection, no sample purification and no molecule label. Graphene is two-dimensional crystal material that is composed of honeycomb lattice structure with six-membered carbocycle. As a new type material, it has attracted many scientists. For its unique structure and physical property, it can significantly improve sensor performance when it is combined with SPR sensor, and opened up a new way to further develop and research SPR sensor. Compared with traditional SPR biosensor, graphene SPR biosensor has greater application areas.First of all, the concept, classification and application area of SPR sensor is shortly introduced in this paper, then the research progress of graphene SPR sensor is summarized, the basic characteristics of surface plasmon polariton(SPP)and numerical computation method of SPR sensor are introduced detailedly at last. The main purpose of this article is to improve the sensitivity of the sensor, three different types of graphene SPR biosensor models are designed, and the parameters and performances of structures are analyzed systematically using simulation software of FDTD Solutions.Firstly, one structure of graphene sensor with SiO2 is presented, SiO2 harmonizes with the contradictions that grapheme not only increases sensitivity but also reduces accuracy. The sensitivity of this model is 74°/RIU, it increases by 1 times compared with the conventional SPR sensor.Air layer and bilateral grapheme are added in the second structure. Air layer can harmonize with contradictions between sensitivity and accuracy, grapheme can protect metal and improve sensitivity. The sensitivity of this model is 78°/RIU, it increases by 81% compared with the existing grapheme SPR sensor.The third structure is guided wave SPR structure added PbS. PbS has high refractive index that can enhance field intensity and propagation distance of surface plasmon wave(SPW) at the interface between grapheme and sample, then can improve sensitivity. The sensitivity of this model is148°/RIU, it increases by 243% compared with the current grapheme SPR sensor.