Gold asymmetric split ring resonators (A-SRRs) for nano sensing of estradiol

Abstract

Recent advances have seen asymmetric split ring resonators (A-SRRs) developed as sensing elements to record a shift in their peaks when there is a corresponding change in the surrounding environment. These studies have led to the investigation of Fano resonances associated with the coupling of the resonances of the A-SRRs with the molecular resonances of the analyte. The hormone estradiol (E2) was dissolved in ethanol and evaporated, leaving thickness of a few hundreds of nanometres on top of gold A-SRRs on a silica substrate. The reflectance was measured and a red shift is recorded from the resonators plasmonic peaks. The geometric sizes of the ASRRs are calculated to tune the plasmonic resonances near the molecular resonance of the C-H stretch at nominally 3.33 microns. Corresponding Lumerical modelling of the experimental data is performed using only the intensity and wavelength to match the Fano resonance at modified wavelengths of 3.42 and 3.49 microns.