Accurate single-nanoparticle sizing down to 3 nm with an optofluidic microcavity

TL;DR

This paper introduces a cavity-based dispersive sensing technique capable of detecting and accurately sizing single nanoparticles as small as 3 nm, providing a high-bandwidth, label-free method for detailed nanoparticle analysis.

Contribution

The authors develop a novel analytical model and sensing approach that enables high-precision, quantitative sizing of individual nanoparticles down to 3 nm in diameter.

Findings

Achieved detection and sizing of particles as small as 3 nm

Developed an analytical model for autocorrelation in standing-wave geometry

Provided a high-bandwidth, label-free nanoparticle sensing method

Abstract

Nanoparticles are ubiquitous, and methods that reveal insights into single-particle properties are highly desired to enable their advanced characterization. Techniques that achieve label-free single-nanoparticle detection often lack bandwidth or do not provide quantitative information. Here, we present a cavity-based dispersive sensing method that achieves a high bandwidth to capture all relevant timescales of translational diffusion, and a sensitivity to detect and size single particles with diameters down to 3 nm. We develop an analytical model describing the autocorrelation function for particle diffusion in a standing-wave sensing geometry and propose a method to address the challenges posed by the transient nature of single-particle signals. With this, we achieve quantitative particle sizing with high precision and accuracy, and provide an important tool to analyze single-particle diffusion.