Esfandiari Meisam, Jarchi Saughar, Nasiri-Shehni Paria, Ghaffari-Miab Mohsen
Appl Opt. 2021 Feb 10;60(5):1201-1208. doi: 10.1364/AO.411974.
A biosensor platform based on the plasmonic resonance of graphene in the terahertz (THz) range (0.1 to 10 THz) is designed and investigated. The initial design is to create a nanofluidic channel as a sensing layer in the substrate of a biosensor grounded by metal. The sensor consists of a rectangular graphene patch over the substrate, which can be fed by either an external near-field source or an antenna. The presence of molecules in the nanosensing layer causes small changes in the channel's properties, detectable through the scattering parameters of the designed biosensor. Since biomolecules are poorly absorbed in the initial biosensor, it can be grounded by a graphene sheet that is the same size as the graphene sheet over the substrate, which results in a performance improvement of the biosensor. It is shown that, by increasing the number of graphene sheets between the ground and the patch, high absorption occurs that enhances the sensitivity of the initial surface plasmon resonance THz biosensor. With varying refractive index of the sensing layer (Ns) in the range of 1.3-1.6, the proposed biosensors are investigated and compared with the initial biosensor. It is shown that by applying a graphene sheet between the two graphene sheets in the substrate, a maximum sensitivity of 8470 nm/RIU is achieved, which is a significant improvement, and also a sensitivity improvement of 4130 nm/RIU is achieved at =1.3. In the final section, it is shown that changing the substrate material from silicon (Si) to silica () brings a significant sensitivity enhancement in the proposed biosensor with three graphene sheets, which accounts for 15410 nm/RIU in the best scenario.
设计并研究了一种基于太赫兹（THz，0.1至10 THz）范围内石墨烯等离子体共振的生物传感器平台。初始设计是在由金属接地的生物传感器基板中创建一个纳米流体通道作为传感层。该传感器由基板上方的矩形石墨烯贴片组成，可由外部近场源或天线馈电。纳米传感层中分子的存在会导致通道特性发生微小变化，可通过设计的生物传感器的散射参数检测到。由于生物分子在初始生物传感器中的吸收较差，它可以由与基板上方石墨烯片大小相同的石墨烯片接地，这会提高生物传感器的性能。结果表明，通过增加接地层与贴片之间的石墨烯片数量，会出现高吸收现象，从而提高初始表面等离子体共振太赫兹生物传感器的灵敏度。在传感层折射率（Ns）在1.3 - 1.6范围内变化时，对所提出的生物传感器进行了研究，并与初始生物传感器进行了比较。结果表明，通过在基板中的两个石墨烯片之间应用一个石墨烯片，可实现8470 nm/RIU的最大灵敏度，这是一个显著的改进，并且在Ns = 1.3时灵敏度提高了4130 nm/RIU。在最后一部分，结果表明将基板材料从硅（Si）改为二氧化硅（）会使具有三个石墨烯片的所提出的生物传感器的灵敏度显著提高 , 在最佳情况下可达15410 nm/RIU 。
