Fano resonance in Al nano-dolmen plasmonic structure for enhanced biosensing

•We systematically studied the Fano characteristics of Al nano-dolmen and achieved the continuously turning the Fano dips in visible ranges.•The Fano dips were significantly changed through varying the arm length and aspect ratios of the designed dolmen structure.•We showed that our designed nanostructures exhibit a remarkable spectral plasmonic sensitivity to the tiny refractive index change of the local dielectric environment.•Al dolmen LSP sensors are abundant, meanwhile possess simple, visible distinct and high sensitivity characters that make them owns the potential to product low cost sensing device and play an important role in the field of biosensing and detecting.

Aluminum nanoparticles or nanolayers are low cost and high quality materials for plasmonic sensing. Here we systematically studied the Fano characteristics of Al nano-dolmen and achieved the continuously turning the Fano dips in visible ranges. The Fano dips were significantly changed through varying the arm length of the designed dolmen structure. To further optimize and characterize the Fano resonance of Al nano-dolmen, an intuitive coupling function is used to fit the Fano line shape. More importantly, we showed that our designed nanostructures exhibit a remarkable spectral plasmonic sensitivity to the tiny refractive index change of the local dielectric environment. The refractive index changes that we measured from 1.0 to 1.4 covered most of the ranges that induced by the general molecular bindings like single-stranded DNAs and antibody-antigens.