We demonstrate the realization of (laterally) optically bounded colloidal structures on a liquid-liquid interface of an emulsion droplet. We use DNA tethers to graft the particles to the droplet surface, effectively confining them to a quasi-2D plane with minimum constraints on the lateral movement even when optically trapped in a common single-beam configuration. We show that relatively weak interactions such as depletion can be measured in the optically bounded crystals by video-microscopy imaging and analysis. This illustrates the possible use of our system as template to study optically controlled quasi two-dimensional colloidal assembly on liquid-liquid interfaces.
@article{arxiv.1703.08210,
title = {Optical trapping of colloids at a liquid-liquid interface},
author = {Alessio Caciagli and Darshana Joshi and Jurij Kotar and Erika Eiser},
journal= {arXiv preprint arXiv:1703.08210},
year = {2017}
}