Switchable Elastocapillarity of High-Aspect-Ratio Topographically Structured Surfaces

Area of Science:

• Physics
• Materials Science
• Fluid Dynamics

Background:

• Elastocapillarity, the interaction of elastic and capillary forces, is crucial in microfluidics, biotechnology, and robotics.
• Understanding surface-droplet interactions is key for designing advanced microdevices and controlling fluid behavior.

Purpose of the Study:

• Investigate elastocapillarity on surfaces with switchable, cantilever-like vertical lamellae.
• Analyze the influence of lamellar flexibility and substrate adhesion on water droplet sliding dynamics.
• Determine how water droplets deform lamellae based on their mechanical properties and adhesion.

Main Methods:

• Fabrication of lamellae with varying mechanical properties and adhesion to a substrate (strong, intermediate, weak).
• Observation and analysis of water droplet sliding behavior on these lamellar surfaces.
• Characterization of lamellar deformation in response to droplet interaction.

Main Results:

• Lamellar material and substrate type do not significantly affect droplet sliding.
• Freely moving lamellae facilitate the fastest droplet sliding due to capillary forces.
• Rigid lamellae with strong/intermediate adhesion resist droplet-induced deformation.
• Soft lamellae with strong/intermediate adhesion deform at the upper parts.
• Both rigid and soft lamellae with weak adhesion are deformed by sliding droplets.

Conclusions:

• Lamellar flexibility and adhesion critically influence droplet sliding speed and droplet-induced deformation.
• Weak adhesion conditions allow for significant lamellar deformation by sliding droplets.
• The findings offer insights into designing surfaces for controlled microfluidic and biotechnological applications.