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. 2018 Jul 23;90(16):9813–9820. doi: 10.1021/acs.analchem.8b01759

Figure 2.

Figure 2

Size uniformity of droplets generated by PTE. (a) While microfluidically prepared emulsions are monodispersed, untemplated vortexed emulsions are not. (b) For certain conditions, vortexing with particle templates allows generation of monodispersed emulsions. To identify the best conditions, we test different particle compositions and aqueous-soluble surfactants. The fraction of droplets containing a single hydrogel particle is determined by image analysis (bar graphs on right). PAA and PEG-templated emulsions with Triton yield 98.8% (n = 433) and 99.1% (n = 683) single-particle droplets, respectively. (c) We quantify the monodispersity of the resultant emulsions by image analysis, plotting as histograms. Untemplated vortexing yields polydispersed emulsions, with 4.3% of diameters between 35–40 μm (n = 561), while microfluidic generation yields monodispersed emulsions, with 95.7% of droplet diameters between 35–38 μm (n = 816). PTE droplets contain either a single hydrogel core (58%, 35–40 μm) or no hydrogel particle (42%, <35 μm). The no-particle droplets, however, due to their small sizes, contribute to <5% of the total sample volume (n = 1421).