Nano-gap electrode dielectrophoresis for tether-free trapping and interferometric-scattering detection of single 20 nm particles

TL;DR

This paper introduces a combined dielectrophoresis and interferometric scattering method for label-free detection and manipulation of 20 nm nanoparticles, enhancing detection sensitivity and enabling new nanotechnology applications.

Contribution

The study presents a novel integrated approach that combines DEP trapping with iSCAT detection, achieving high-sensitivity, label-free nanoparticle detection and manipulation at the nanoscale.

Findings

Successfully trapped and detected 20 nm polystyrene nanoparticles.

Achieved up to 20-fold signal-to-noise ratio enhancement using digital lock-in detection.

Demonstrated potential applications in nanoparticle assembly and nanofluidic devices.

Abstract

Accurate detection and characterization of nanoparticles within confined spaces is crucial for applications ranging from nanofluidics to biotechnology. We present a novel approach that combines interferometric scattering (iSCAT) detection with trapping by dielectrophoresis (DEP) to achieve label-free detection of nanoparticles that are trapped and/or actuated between nano-gap electrodes. DEP utilizes the interaction between the induced dipole of the particle and the applied electric field to create a trapping potential. We demonstrate our method by trapping and label-free detection of down to 20 nm polystyrene nanoparticles. Additionally, we demonstrate that the signal-to-noise ratio of our detection can be boosted up to 20-fold by periodic actuation of the nanoparticle in the trap. This is done by a digital lock-in detection scheme on the modulated scattering signal. Our method holds promise for various applications, including assembly of nanoparticles, single-particle property analysis, and nanofluidic devices.