Efficient Microparticle Trapping with Plasmonic Annular Apertures Arrays

TL;DR

This paper presents a novel plasmonic tweezers system using annular aperture arrays to trap and transport microparticles efficiently with low laser power, supported by simulations and experimental validation.

Contribution

It introduces a new plasmonic trapping method based on annular aperture arrays, combining theoretical modeling with experimental demonstration of particle trapping and transport.

Findings

Successful trapping of 0.5 um and 1 um particles.

Low laser power (<1.5 mW/um2) used for trapping.

Simulation results match experimental observations.

Abstract

In this work, we demonstrate trapping of microparticles using a plasmonic tweezers based on arrays of annular apertures. The transmission spectra and the E- field distribution are simulated to calibrate the arrays. Theoretically, we observe sharp peaks in the transmission spectra for dipole resonance modes and these are redshifted as the size of the annular aperture is reduced. We also expect an absorption peak at approximately 1,115 um for the localised plasmon resonance. Using a laser frequency between the two resonances, multiple plasmonic hotspots are created and used to trap and transport micron and submicron particles. Experimentally, we demonstrate trapping of individual 0.5 um and 1 um polystyrene particles and particle transportation over the surface of the annular apertures using less than 1.5 mW/um2 incident laser intensity at 980 nm.