Fig. 5.

Effect of plasma treatment duration on double emulsion generation. Short plasma treatment times result in channels with intermediate wettability that are unable to form double emulsions (10 s), while longer treatment times yield more hydrophilic channels that yield small, monodisperse double emulsions (60 s). While the 60 s plasma treatment wears off after ~30 min, the 180 s treatment is stable for ~3 hrs, providing longer useful operation time. Flow rates used are the same for all conditions: 80, 80 and 250 μL/hr for inner, middle and outer phases, respectively.