Gold cauldrons as efficient candidates for plasmonic tweezers

Abstract

In this report, gold cauldrons are proposed and proved as efficient candidates for plasmonic tweezers. Gold cauldrons benefit from high field localization in the vicinity of their apertures, leading to particle trapping by a reasonably low power source. The plasmonic trapping capability of a single gold cauldron and a cauldrons cluster are studied by investigating the plasmon-induced variations of the optical trap stiffness in a conventional optical tweezers configuration. This study shows that the localized plasmonic fields and the consequent plasmonic forces lead to enhanced trap stiffness in the vicinity of the cauldrons. This observation is pronounced for the cauldrons cluster, due to the additive plasmonic fields of the neighboring cauldrons. Strong direct plasmonic tweezing by the gold cauldrons cluster is also investigated and confirmed by our simulations and experimental results. In addition to the presented plasmonic trapping behavior, gold cauldrons benefit from a low cost and simple fabrication process with acceptable controllability over the structural average dimensions and plasmonic behavior, making them attractive for emerging lab-on-a-chip optophoresis applications.

Plasmonic Optical Tweezers for Particle Manipulation: Principles, Methods, and Applications

“…Isolated plasmonic structures, including nanoarray without near-field interaction, , are commonly used to manipulate micro- and nanoparticles in optical plasmonic tweezers. Different structures have been applied, which range from simple shapes, such as nanodisk, nanowire, , and nanopillar, to complex configurations, like nanodiabolo, nanobowtie ring, and microcauldrons . When illuminated by light of the corresponding resonance wavelength, a strong field enhancement (| E / E 0 | 2 ) is expected.…”

“…Different structures have been applied, which range from simple shapes, such as nanodisk, 100 nanowire, 101,102 and nanopillar, 103 to complex configurations, like nanodiabolo, 104 nanobowtie ring, 83 and microcauldrons. 105 When illuminated by light of the corresponding resonance wavelength, a strong field enhancement (|E/E 0 | 2 ) is expected. In the case of silver nanorods, this enhancement could be as high as 3500.…”

Tunable plasmonic tweezers based on nanocavity structure for multi-site trapping

“…In addition, plasmonic nanocavity structures can also be used as nanovials to store solution and analyte, the opens up the possibility to obtain the full-band SERS spectrum of macromolecules [24,25]. Therefore, the nanocavity structure with possesses excellent electromagnetic field enhancement performance is a promising strategy to achieve stable trapping, which has attracted more and more attention from researchers [26][27][28][29]. Such as Khosravi et al investigated the plasmonic trapping ability of single gold cauldron and cauldron clusters to polystyrene microspheres with a radius of 500 nm [26].…”

Anisotropic optical response of gold-silver alloys

“…In the last decade, the rapid progress of the plasmonic field occurred due to the advance of new techniques of fabrication and characterization of pure metallic structures 4,8 . More recently, a change of paradigm driven by the maturing of nanofabrication methods and the systematic analysis of alloyed nanostructured systems [9][10][11] resulted in the rise of applications of this novel system as plasmonic tweezers 12 , hydrogen sensors 13 , photocatalystis 14 , and bio-sensors 15 .…”