Opto-thermoelectric trapping of Fluorescent Nanodiamonds on Plasmonic Nanostructures

TL;DR

This paper demonstrates a novel opto-thermoelectric trapping method using plasmonic nanostructures to manipulate and analyze fluorescent nanodiamonds with low power and long working distance, advancing biological imaging techniques.

Contribution

It introduces a new nano-optical trapping approach combining thermoplasmonic fields and opto-thermoelectric effects for single nanodiamond manipulation.

Findings

Successfully trapped single FNDs using low power illumination.

Captured spectral signatures of individual FNDs.

Tracked FND dynamics around different plasmonic structures.

Abstract

Deterministic optical manipulation of fluorescent nanodiamonds (FNDs) in fluids has emerged as an experimental challenge in multimodal biological imaging. Designing and developing nano-optical trapping strategies to serve this purpose is an important task. In this letter, we show how chemically-prepared gold nanoparticles and silver nanowires can facilitate Opto-thermoelectric force to trap individual entities of FNDs using a long working distance lens, low power-density illumination (532 nm laser, 12 ${\mu}W/{\mu}m^2$). Our trapping configuration combines the thermoplasmonic fields generated by individual plasmonic nanoparticles and the opto-thermoelectric effect facilitated by the surfactant to realise a nano-optical trap down to a single FND 120 nm in diameter. We utilise the same trapping excitation source to capture the spectral signatures of single FNDs and track their position. By tracking the FND, we observe the differences in the dynamics of FND around different plasmonic structures. We envisage that our drop-casting platform can be extrapolated to perform targeted, low-power trapping, manipulation, and multimodal imaging of FNDs inside biological systems such as cells.