In this paper, design of biosensor structure based on localized surface plasmon (LSPR) of plasmonic nanostructures is presented. Change in refrective index at boundary of metal-dielectric lead to a shift in resonance peak of LSPR structures. Plasmonic nano­structurs are very sensitive to changes of surrounding environment. Increasing refractive index of surrounding environment cause a red shift in LSPR spectrum of these structures. Thus with this feature we can distinguish absorption or connection of molecules to the surface without prelabeling (Label Free). In this article we introduced a new dumbbell shape nanoparticle and its ability in biosensing is investigated. Numerical simulations show that a high sensitivity of 1323nm/RIU for refractive index changes of surrounding the suspended gold nanostructure with a figure of merit (FOM) of 5.6.

Keywords: optical biosensing, localized surface plasmon resonance, biosensor, nono structure

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