Mapping micrometer-scale wetting properties of superhydrophobic surfaces

Area of Science:

• Materials Science
• Surface Science
• Nanotechnology

Background:

• Superrepellent surfaces are crucial for antifouling and heat-transfer applications.
• Traditional characterization relies on indirect contact angle measurements, which lack quantitative resolution.
• Existing methods cannot resolve microscale wetting variations on surfaces.

Purpose of the Study:

• To develop a direct, high-resolution method for measuring wetting forces on superrepellent surfaces.
• To overcome the limitations of semiquantitative contact angle measurements.
• To spatially map micrometer-scale wetting properties and analyze droplet dynamics.

Main Methods:

• Attaching a micrometric-sized droplet to an atomic force microscope (AFM) cantilever.
• Directly measuring adhesion and friction forces with nanonewton resolution.
• Spatially mapping wetting properties and observing time-resolved pinning-depinning dynamics.

Main Results:

• Direct measurement of adhesion and friction forces at the micrometer scale.
• High-resolution spatial mapping of superhydrophobic surface wetting properties.
• Observation of time-resolved droplet pinning-depinning dynamics during detachment and movement.

Conclusions:

• AFM-based force measurements provide direct, quantitative insights into wetting phenomena.
• This method surpasses traditional contact angle measurements in resolving microscale wetting variations.
• The technique enables detailed characterization of superrepellent surfaces for advanced applications.