10.1063/1.4895779.5

Abstract

The study of wetting characteristics of low-energy (e.g., superhydrophobic) liquid-repellent surfaces is of great importance towards optimal design of such micro/nano-engineered surfaces. The most common technique to accomplish this involves bringing a drop generated at the needle-tip close to the characterizing substrate with a goal to deposit it on the substrate, which often becomes a challenge when the surface energy of the drop-substrate combination is comparable to the needle-drop system. In this paper, we proposed a new “needle-free” drop deposition technique, which overcomes this challenge for characterization the low-energy substrates. This is achieved by placing an additional low-energy substrate above the characterizing substrate and allowing the drop-needle combination to impact on this additional substrate. This technique is not only independent of the wetting properties of the needle and the characterizing substrate but is also independent of the liquid drop properties, thereby making it a very universal technique for characterizing substrate in air medium.