Label-Free Highly Sensitive Hybrid Plasmonic Biosensor for the Detection of DNA Hybridization

A highly sensitive hybrid plasmonic slot-waveguide (HPSW) biosensor based on silicon-on-insulator is proposed and analyzed for DNA hybridization detection. The reported design is based on increasing the light interaction with the sensing region by using slot waveguide with plasmonic material. Due to the high index contrast and plasmonic effect, an ultrahigh optical confinement is achieved in the low-index regions, which enables the detection of the smallest change in the analyte refractive index with high sensitivity. The normalized power confinement, power density, and effective index of the supported modes by the HPSW are analyzed to achieve high-power confinement through the suggested biosensor and hence high sensitivity can be obtained. The HPSW is also incorporated with straight slotted resonator to calculate the sensitivity of the proposed design. The simulation results are calculated using full vectorial finite element method. The reported biosensor has high sensitivity of 1890.4 nm/RIU (refractive index unit), which is the highest in the literature to the best of our knowledge with a detection limit of 2.65 × 10-6RIU.