Figure 4. Water absorption phenomenon on the BGL and SFG.

(a) Environmental Scanning Electron Microscope (E-SEM) observation of water absorption on the SFG. In the initial stage, there are many small water droplets generated environmentally. As the water droplet growing with time, the lots water droplets in the red-dot circle are absorbed into the SFG. (b) Water droplet at the interface between a water droplet and the junction of the SFG. As the water droplet reducing with time, the wetted junction of the SFG can be observed in the red-dot circle. This triple line movement shows pinning characteristics and it means the wetted junction exhibits hydrophilic property.