scholarly journals High Sensitive Biosensors Based on the Coupling Between Surface Plasmon Polaritons on Titanium Nitride and a Planar Waveguide Mode

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1784 ◽  
Author(s):  
Junior Asencios ◽  
Ramiro Moro ◽  
Clemente Luyo ◽  
Arturo Talledo

High sensitivity biosensors based on the coupling of surface plasmon polaritons on titanium nitride (TiN) and a planar waveguide mode were built; they were proved by sensing three different media: air, water and dried egg white; sensors described here could be useful for sensing materials with a refractive index between 1.0 and 1.6; in particular, materials of biological interest with a refractive index in the range 1.3–1.6, like those containing biotin and/or streptavidin. They were built by depositing Nb2O5/SiO2/TiN multilayer structures on the flat surface of D-shaped sapphire prisms by using the dc magnetron sputtering technique. Attenuated total reflection (ATR) experiments in the Kretschmann configuration were accomplished for the air/TiN/Prism and S/Nb2O5/SiO2/TiN/Prism structures, S being the sample or sensing medium. ATR spectra for plasmons at the TiN/air interface showed a broad absorption band for angles of incidence between 36 and 85°, with full width at half maximum (FWHM) of approximately 40°. For the S/Nb2O5/SiO2/TiN/Prism structures, ATR spectra showed a sharp reflectivity peak, within the broad plasmonic absorption band, which was associated with Fano resonances. The angular position and FWHM of the Fano resonances strongly depend on the refractive index of the sensing medium. ATR spectra were fitted by using the transfer-matrix method. Additionally, we found that angular sensitivity and figure of merit increase with increasing the refractive index of the sensing medium.

2021 ◽  
Author(s):  
Zhaoyi Chen ◽  
Ke Feng ◽  
Zhibin Chen ◽  
Jinxing Shen ◽  
Huanliang Li

Abstract In this study, we reported a silver sinusoidal nanograting used in microchannels, forming H2O/Ag/NOA heterostructure, and studied the impact of interactions of grating-coupled surface Plasmon polaritons (SPPs) on Surface-enhanced Raman Scattering (SERS). FDTD simulations showed that when the refractive index of NOA is close to that of H2O, there were two modes of odd coupling and even coupling between SPPs. Additionally, the thinner the Ag grating, the stronger the coupling, accompanied by the frequency shift of the two coupling modes. We also estimated the influence of refractive index of the surrounding medium on SPPs coupling by varying the dielectric of the upper and lower layer of Ag grating. Our experimental results were supported by FDTD calculations, which confirmed the importance of the interactions of grating-coupled SPPs in the design of SERS substrate.


2020 ◽  
Vol 28 (10) ◽  
pp. 14536 ◽  
Author(s):  
Mena N. Gadalla ◽  
Kundan Chaudhary ◽  
Christine M. Zgrabik ◽  
Federico Capasso ◽  
Evelyn L. Hu

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