Optothermal Trapping of Fluorescent Nanodiamonds using a Drop-casted Gold Nanoparticle

Abstract

Deterministic optical manipulation of fluorescent nanodiamonds (FNDs) in a fluid environment has emerged as an experimental challenge in multimodal biological imaging. The design and development of nano-optical trapping strategies to serve this purpose is an important task. In this letter, we show how a drop-casted gold nanoparticle (Au np) can facilitate optothermal potential to trap individual entities of FNDs using a low power density illumination (532nm laser, 0.1 mW/µm 2 ). We utilize the same trapping excitation source to capture the spectral signatures of single FNDs and track their position. Furthermore, by tracking the dynamics of FND, we measure the trapping stiffness as a function of laser power and surfactant concentration and emphasize their relevance as vital parameters for nano-manipulation. Our trapping configuration combines the thermoplasmonic fields generated by individual gold nanoparticles and the optothermoelectric effect facilitated by surfactants to realize a nano-optical trap down