Figure 2. Microscopic visualization of liquid droplet evaporation and ice bridging dynamics.

(a) Selected snapshots showing the detailed droplet evaporation and ice bridging dynamics on the hierarchical superhydrophobic surface. All the liquid droplets circled with white dashed line with diameter ranging from ~15 to ~37 μm evaporate (from 0 s to 46 s) without successfully bridging to the invading frost, eventually forming a “depletion zone” at ~62 s. (b) Selected snapshots showing the droplet evaporation and ice bridging dynamics on the nanograssed superhydrophobic surface. Droplet 3 with a S < 1 is successfully frozen by the droplet 5 at the time point of 12 s, whereas droplet 4 with a S > 1 gradually disappears within 34 s without a connection with the droplet 5. (c) Schematic drawing illustrating the dependence of droplet evaporation and ice bridging on the bridging parameter.