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Open AccessArticle

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

1
Facultad de Ciencias, Universidad Nacional de Ingeniería, Lima 15333, Peru
2
Tianjin International Center for Nano Particles and Nano Systems, Tianjin University, Tianjin 300072, China
*
Author to whom correspondence should be addressed.
Sensors 2020, 20(6), 1784; https://doi.org/10.3390/s20061784
Received: 16 February 2020 / Revised: 20 March 2020 / Accepted: 20 March 2020 / Published: 23 March 2020
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. View Full-Text
Keywords: surface plasmon polaritons; plane waveguide; Fano resonance surface plasmon polaritons; plane waveguide; Fano resonance
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MDPI and ACS Style

Asencios, J.; Moro, R.; Luyo, C.; Talledo, A. High Sensitive Biosensors Based on the Coupling Between Surface Plasmon Polaritons on Titanium Nitride and a Planar Waveguide Mode. Sensors 2020, 20, 1784.

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