Accurate Single-Nanoparticle Sizing down to 3 nm with an Optofluidic Microcavity

Area of Science:

• Nanoscience and nanotechnology
• Analytical chemistry
• Physical chemistry

Background:

• Single-nanoparticle characterization is crucial for advanced applications.
• Existing label-free detection methods often lack sufficient bandwidth or quantitative data.
• There is a need for high-bandwidth, sensitive techniques for analyzing nanoparticle diffusion.

Purpose of the Study:

• To present a cavity-based dispersive sensing method for label-free single-nanoparticle detection and sizing.
• To achieve high bandwidth and sensitivity for capturing translational diffusion dynamics.
• To enable quantitative analysis of single-particle properties, including size.

Main Methods:

• Development of a cavity-based dispersive sensing platform.
• Implementation of a standing-wave sensing geometry.
• Creation of an analytical model for particle diffusion autocorrelation functions.
• Methodology to handle transient single-particle signals.

Main Results:

• Demonstration of label-free detection and sizing of single nanoparticles down to 3 nm in diameter.
• Achieved high bandwidth to capture translational diffusion time scales.
• Quantitative particle sizing with high precision and accuracy.

Conclusions:

• The developed cavity-based sensing method provides a sensitive and high-bandwidth tool for single-nanoparticle analysis.
• This technique enables quantitative sizing and diffusion analysis of nanoparticles.
• It represents a significant advancement in nanoparticle characterization.