Detection of Single Molecules Illuminated by a Light-Emitting Diode

TL;DR

This paper demonstrates the optical detection of single molecules using a standard green LED for illumination, comparing its effectiveness with traditional laser methods, and discusses the factors influencing detection quality.

Contribution

It introduces a novel approach for single-molecule detection using a commercially available LED, expanding the tools available for biological imaging and sensing.

Findings

LED-based illumination achieves comparable detection to laser illumination

Analysis of factors affecting signal-to-noise ratio in LED-based detection

Theoretical and experimental methods to optimize detection parameters

Abstract

Optical detection and spectroscopy of single molecules has become an indispensable tool in biological imaging and sensing. Its success is based on fluorescence of organic dye molecules under carefully engineered laser illumination. In this paper we demonstrate optical detection of single molecules on a wide-field microscope with an illumination based on a commercially available, green light-emitting diode. The results are directly compared with laser illumination in the same experimental configuration. The setup and the limiting factors, such as light transfer to the sample, spectral filtering and the resulting signal-to-noise ratio are discussed. A theoretical and an experimental approach to estimate these parameters are presented. The results can be adapted to other single emitter and illumination schemes.