Maximizing the Surface Sensitivity of LSPR Biosensors through Plasmon Coupling-Interparticle Gap Optimization for...

Area of Science:

• Plasmonics
• Nanotechnology
• Biosensing

Background:

• Localized Surface Plasmon Resonance (LSPR) biosensors rely on optical properties of nanoparticles.
• Coupling between plasmonic nanoparticles can enhance sensor sensitivity.

Purpose of the Study:

• To investigate the bulk and surface refractive index sensitivities of coupled plasmonic nanosphere and nano-ellipsoid dimers.
• To quantify the effect of plasmonic coupling on LSPR biosensor sensitivity.

Main Methods:

• Simulations using the boundary element method (BEM).
• Quantification of enhancement factor based on plasmon extinction peak shifts.
• Modeling bulk sensitivity by changing the dielectric medium.
• Modeling surface sensitivity by depositing dielectric layers.

Main Results:

• Optimized interparticle gaps utilize up to 80% of the optical response range.
• Plasmonic coupling enhances sensitivity by ~3-4 times compared to single particles.
• Surface sensitivity enhancement is significantly higher than bulk refractive index sensitivity (RIS) enhancement.

Conclusions:

• Plasmonic coupling is crucial for optimizing nanoparticle arrangements in biosensor applications.
• Tailoring interparticle gaps to molecule size maximizes molecular sensitivity.
• The presented methodology aids in optimizing biosensor fabrication technologies.