Sensing of Organic Vapors with Plasmonic Distributed Bragg Reflectors

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Sensing

Background:

• Advancements in air quality monitoring rely on diverse sensor technologies.
• Polymer-based Distributed Bragg Reflectors (DBRs) show promise for cost-effective, portable volatile organic compound (VOC) sensors.
• A key challenge is achieving sufficient refractive index contrast in polymer DBR fabrication.

Purpose of the Study:

• To fabricate plasmonic DBR sensors using low-temperature plasma techniques.
• To investigate their potential for detecting VOCs.
• To develop an optical model linking sensor properties, microstructure, and performance.

Main Methods:

• Synthesized silver (Ag) nanoparticles via gas aggregation and embedded them into poly(lactic acid) (PLA) layers to form nanocomposites.
• Fabricated a 6-bilayer plasmonic DBR by alternating plain PLA and Ag-PLA nanocomposite layers.
• Utilized a generalized Maxwell-Garnett approach for optical modeling.

Main Results:

• Achieved a plasmonic DBR with 77% reflectance at 570 nm.
• Demonstrated sensor response to ethanol vapors, causing a red-shift in reflection peak to 640 nm and color change due to polymer swelling.
• The developed model accurately reproduced DBR spectra, accounting for structural changes and nanoparticle behavior.

Conclusions:

• Plasmonic DBRs offer a promising route for low-cost, real-time VOC sensing.
• The fabricated sensors exhibit optical changes upon exposure to VOCs, indicating sensing capability.
• The optical model provides accurate prediction of sensor performance and degradation effects.