The Design of a Glycerol Concentration Sensor Based on an LRSPP Hybrid Photonic Biosensor

Area of Science:

• Photonics and Plasmonics
• Nanotechnology
• Biosensing

Background:

• Surface plasmon polariton (SPP) sensors offer high sensitivity for refractive index (RI) detection.
• On-chip integration of plasmonic sensors is crucial for miniaturization and point-of-care applications.
• Silicon nitride (Si3N4) waveguides provide a robust platform for integrated photonic devices.

Purpose of the Study:

• To theoretically design and optimize an on-chip silicon nitride ridge waveguide sensor utilizing long-range surface plasmon polaritons (LRSPPs).
• To evaluate the sensor's performance for refractive index sensing applications.
• To assess the potential of the proposed sensor for point-of-care diagnostics.

Main Methods:

• Theoretical design and optimization of a Si3N4 ridge waveguide coupled with a gold (Au) film on a Cytop polymer layer.
• Finite Element Method (FEM) for geometric parameter optimization at a 633 nm optical wavelength.
• Transfer Matrix Method (TMM) for spectral performance evaluation across a 580–680 nm range.

Main Results:

• The sensor design utilizes a gold film for plasmonic resonance on a Cytop polymer layer.
• An increasing analyte refractive index causes a redshift in the interference spectrum.
• Achieved sensitivities of 6313 dB/cm/RIU and 251.82 nm/RIU with a 400 nm wide and 25 nm thick Au layer.

Conclusions:

• The proposed on-chip Si3N4 waveguide LRSPP sensor demonstrates high sensitivity for refractive index detection.
• The sensor's compact and simple construction holds significant potential for point-of-care applications.
• This integrated photonic approach offers a promising platform for future biosensing technologies.