# Plasmonic Gas Sensing based on Cavity-Coupled Metallic Nanoparticles

## TL;DR

This study demonstrates a reversible, high-sensitivity gas sensor using cavity-coupled gold nanoparticles that detect humidity changes through variations in scattering intensity, offering a simple and effective approach for gas sensing.

## Contribution

It introduces a lithography-free, cavity-coupled nanoparticle system for humidity sensing with high sensitivity and reversibility, advancing gas sensing technology.

## Key findings

- Sensitivity of 0.12 dB/% RH over 45-75% RH
- Resolution better than 0.5% RH
- Full reversibility with minimal hysteresis

## Abstract

Here we demonstrate the gas sensing ability of cavity-coupled metallic nanoparticle systems, comprising gold nanoparticles separated from a gold mirror with a polymer spacer. An increase in relative humidity (RH) causes the spacer to expand, which induces a significant reduction of nanoparticle scattering intensity, as the scattering is highly dependent on the cavity-nanoparticle coupling that closely relates to the nanoparticle-mirror distance. This lithography-free structure enables a remarkable averaging sensitivity at 0.12 dB/% RH and 0.25 dB/% RH over RH range (45-75%), possessing an estimated resolution better than 0.5% RH with full reversibility and almost zero-hysteresis, exhibiting notable gas sensing potentials.

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Source: https://tomesphere.com/paper/1703.08276