Detecting single viruses and nanoparticles using whispering gallery microlasers

TL;DR

This paper introduces a highly sensitive, label-free detection method using whispering gallery microlasers capable of identifying individual nanoparticles and viruses with resolutions down to 10-15 nm, suitable for real-time applications.

Contribution

It presents a novel detection technique leveraging ultra-narrow linewidth microlasers with frequency splitting for single nanoparticle and virus detection, surpassing existing photonic device limits.

Findings

Detected nanoparticles as small as 10-15 nm in radius.

Achieved real-time, label-free detection in air and aqueous environments.

Demonstrated detection of Influenza A virions.

Abstract

Detection and characterization of individual nano-scale particles, virions, and pathogens are of paramount importance to human health, homeland security, diagnostic and environmental monitoring[1]. There is a strong demand for high-resolution, portable, and cost-effective systems to make label-free detection and measurement of individual nanoparticles, molecules, and viruses [2-6]. Here, we report an easily accessible, real-time and label-free detection method with single nanoparticle resolution that surpasses detection limit of existing micro- and nano-photonic devices. This is achieved by using an ultra-narrow linewidth whispering gallery microlaser, whose lasing line undergoes frequency splitting upon the binding of individual nano-objects. We demonstrate detection of polystyrene and gold nanoparticles as small as 15 nm and 10 nm in radius, respectively, and Influenza A virions by monitoring changes in self-heterodyning beat note of the split lasing modes. Experiments are performed in both air and aqueous environment. The built-in self-heterodyne interferometric method achieved in a microlaser provides a self-reference scheme with extraordinary sensitivity [7,8], and paves the way for detection and spectroscopy of nano-scale objects using micro- and nano-lasers.