Reshaping sub-millimetre bubbles from spheres to tori

Area of Science:

• Soft Matter Physics
• Materials Science
• Surface Mechanics

Background:

• Shape-changing materials are crucial for advanced applications in acoustics and robotics.
• Controlling the topology of materials, in addition to their shape, presents unique challenges and opportunities.

Purpose of the Study:

• To report the creation of sub-millimetre bubbles capable of reversible topological transformations.
• To investigate the mechanism enabling rapid shape and topological changes in these bubbles.
• To explore potential applications in materials science and surface mechanics.

Main Methods:

• Fabrication of sub-millimetre bubbles stabilized by a solid-like protein nanoparticle film.
• Application of controlled pressure treatments to induce shape and topological changes.
• Microscopic observation and analysis of bubble morphology and protein expulsion.

Main Results:

• Demonstrated reversible transitions between spherical and toroidal topological classes in the bubbles.
• Observed stable toroidal bubble forms persisting for several days, often matching Clifford torus dimensions.
• Identified protein expulsion as the key mechanism for enabling rapid topological class crossing.

Conclusions:

• Sub-millimetre protein-stabilized bubbles can rapidly and reversibly change topological class via pressure treatment.
• This rapid topological transformation capability offers advantages over existing methods for studying surface mechanics.
• The findings suggest novel pathways for developing lightweight materials with high surface areas.