Plasmonic Au islands on polymer nanopillars

Area of Science:

• Nanotechnology
• Materials Science
• Optics

Background:

• Localized surface plasmon resonance (LSPR) sensors offer high sensitivity for detecting analytes.
• Improving LSPR sensor sensitivity often involves optimizing the geometry and environment of plasmonic nanoparticles.
• Current methods for fabricating nanostructured plasmonic substrates can be complex and costly.

Purpose of the Study:

• To develop a simple and versatile method for fabricating plasmonic gold (Au) islands on polymer nanopillars.
• To investigate the effect of nanopillar height on the optical properties of supported Au islands.
• To demonstrate the fabrication of flexible plasmonic substrates using this technique.

Main Methods:

• Colloidal lithography was employed to create polymer nanopillars.
• The height of polymer nanopillars was controlled by adjusting the initial polymer film thickness.
• Gold (Au) nanoparticles were deposited onto the polymer nanopillars to form plasmonic islands.

Main Results:

• Fabrication of plasmonic Au islands on polymer nanopillars was successfully achieved.
• Increased nanopillar height led to a blue shift in the absorption spectrum of Au islands, attributed to a reduced effective refractive index.
• A plateau in the blue shift was observed for pillar heights above approximately 40 nm, consistent with electromagnetic field decay lengths.
• Pillar-supported Au islands were demonstrated on flexible polymer foil.

Conclusions:

• The described colloidal lithography method is effective for fabricating plasmonic Au islands on polymer nanopillars.
• Nanopillar height is a critical parameter for tuning the optical response of LSPR sensors.
• The technique shows promise for developing flexible plasmonic substrates for various sensing applications.