Fig. 3.

(A) Electrical measurements of the average oil film thickness between noncoalescing water droplets for substrates infused with hexadecane (○) at room temperature (22 °C), 50 cSt silicone oil (Δ) cooled to the dew point (17 °C), or 350 cSt silicone oil (□) cooled to the dew point (now 7 °C due to change in humidity). Multiple trials for each oil are denoted by different colors, and the final data point for each trial indicates film collapse and coalescence. The drainage rates were in good agreement with the model (Eq. 6) as denoted by the dotted trend lines; see SI Appendix, Table S3 for the values used in Eq. 6. The initial film thickness increased with viscosity and could also be increased by adding more excess oil to the substrate, as demonstrated here with 50 cSt silicone oil. (B and C) Side-view and top-down photographs of noncoalescing water droplets with inserted electrodes.