Figure 2.

Illustration of the experimental setup. (A) Front view, (B) top view, and (C) front view of the Al cover with glass windows and a small opening with 2 mm diameter at the top for inserting dosing needle. A Peltier element under the Al plate, two temperature sensors, and a temperature controller guarantee a homogeneous temperature contribution. For water droplet evaporation process, the Al cover (black dash line in A) is removed to achieve atmospheric humidity and allowing droplet evaporation. For soaking experiments to investigate the effect of water adsorption on WCA, the groove integrated in the Al base plate is filled with water to create an atmosphere of saturated humidity (blue dash line in A and details seen in B), and the Al cover is placed to maintain the saturated humidity inside the chamber.