| Nanodroplets on a solid surface (i.e. surface nanodroplets) have practical implications for high-throughput chemical and biological analysis, lubrications, laboratory-on-chip devices, and near-field imaging techniques. Oil nanodroplets can be produced on a solid–liquid interface in a simple step of solvent exchange in which a good solvent of oil is displaced by a poor solvent. In this work, we experimentally and theoretically investigate the formation of nanodroplets by the solvent exchange process under well-controlled flow conditions. We find significant effects from the flow rate and the flow geometry on the droplet size. We develop a theoretical framework to account for these effects. The talk will further discuss a basic principle for the symmetrical arrangement of surface nanodroplets during their growth under simple flow conditions. In our model system, nanodroplets nucleate at the rim of spherical cap microstructures on a substrate. We find that, while growing, the nanodroplets self-organise into highly symmetric arrangements, with respect to position, size, and mutual distance. We show and explain how the nanodroplets acquire the symmetrical spatial arrangement during their competitive growth and why and how the competition enhances the overall growth rate of the nucleated nanodroplets. This mechanism behind the nanodroplet self-organisation promises a simple approach for the location control of droplets with a volume down to attoliters.
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| Prof. Xuehua Zhang is now an associate professor in Royal Melbourne Institute of Technology (RMIT) University, Australia. She is an Australian Research Council Future Fellow and Guest Professor of University of Twente, The Netherlands. Her research interest includes colloid and interface science and nanomaterials. She has published more than 80 peer reviewed scientific papers including PNAS, PRL, JACS, ANGEW CHEM INT EDIT, ACS Nano etc (Total citations > 2350; h-index = 24). Prof. Zhang serves as an associate editor of The European Physical Journal E.
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