Design of a label-free multiplexed biosensing platform based on an ultracompact plasmonic resonant cavity

A multi-analyte biosensing platform for the selective label-free detection of protein biomarkers has been designed through a three-dimensional model based on the finite element method. The sensing element of the platform is a planar plasmonic nanocavity, consisting of a one-dimensional periodic structure (Bragg grating) in gold, with a defect, placed on the buried oxide of a silicon-on-insulator substrate. The footprint of this sensing element, which has a good chemical stability, is only 1.57 μm2. The sensor has a detection limit of 128 pg/mm2 and a surface sensitivity of 1.8 nm/nm.