Tracking Single Particles using Surface Plasmon Leakage Radiation Speckle

TL;DR

This paper introduces a novel, label-free method for tracking tiny biological particles using surface plasmon leakage radiation speckle, combining interferometric detection and surface plasmon confinement for high accuracy.

Contribution

The paper presents a new technique that enhances particle tracking sensitivity by leveraging surface plasmon interference with speckle fields, enabling sub-wavelength precision.

Findings

Method achieves sub-wavelength tracking accuracy.

Robustness to noise demonstrated via simulations.

Analytic framework supports experimental feasibility.

Abstract

Label free tracking of small bio-particles such as proteins or viruses is of great utility in the study of biological processes, however such experiments are frequently hindered by weak signal strengths and a susceptibility to scattering impurities. To overcome these problems we here propose a novel technique leveraging the enhanced sensitivity of both interferometric detection and the strong field confinement of surface plasmons. Specifically, we show that interference between the field scattered by an analyte particle and a speckle reference field, derived from random scattering of surface plasmons propagating on a rough metal film, enables particle tracking with sub-wavelength accuracy. We present the analytic framework of our technique and verify its robustness to noise through Monte Carlo simulations.