Improved nanobubble immobility induced by surface structures on hydrophobic surfaces

Area of Science:

• Surface Science
• Fluid Dynamics
• Materials Science

Background:

• Boundary slip at solid-liquid interfaces, driven by surface nanobubbles, is key to reducing drag in micro/nanofluidics.
• Nanobubble mobility poses challenges for stable slip boundary conditions.
• Improving nanobubble immobility is critical for practical applications.

Purpose of the Study:

• To investigate methods for enhancing nanobubble immobility on hydrophobic surfaces.
• To understand the role of surface structures in nanobubble stabilization.
• To develop a model explaining the mechanisms behind improved nanobubble immobility.

Main Methods:

• Experimental study of nanobubble immobility on continuously and partially coated polystyrene films.
• Surface characterization using nanoindentation analysis.
• Development of a theoretical model based on contact angle hysteresis and surface tension.

Main Results:

• Significantly improved nanobubble immobility was observed on both continuously and partially coated surfaces.
• Nanoindents formed on the surfaces and island-like structures on partially coated films were identified as key factors.
• The developed model confirmed that these structures increase the force required to initiate nanobubble movement.

Conclusions:

• Surface modifications, specifically nanoindents and island structures, effectively enhance nanobubble immobility.
• These findings provide a pathway to more stable and controllable boundary slip in micro/nanofluidic devices.
• The study highlights the importance of surface topography in managing nanobubble behavior for fluid flow applications.