Light-powered active colloids from monodisperse and highly tunable microspheres with a thin TiO₂ shell.

Area of Science:

• Materials Science
• Soft Matter Physics
• Colloid Science

Background:

• Active matter and active colloids are rapidly developing fields.
• There is a need for uniform, tunable model systems for studying moving entities.
• Existing model systems often lack sufficient control over properties.

Purpose of the Study:

• To introduce novel core-shell SiO2-TiO2 microspheres as advanced model systems.
• To demonstrate the tunability and advantages of these core-shell structures.
• To showcase their potential in active matter research.

Main Methods:

• Fabrication of core-shell SiO2-TiO2 microspheres via chemical coating.
• Characterization of microsphere size monodispersity and shape regularity.
• Preparation of Janus TiO2-Pt active colloids using the core-shell spheres.

Main Results:

• Highly monodisperse (4.1% polydispersity) and regular (0.93 circularity) microspheres were produced.
• Janus TiO2-Pt active colloids exhibited enhanced speed and clearer interfaces compared to traditional methods.
• Demonstrated tunability in colloid size, shell thickness, and core particle type.
• Showcased magnetic manipulation and UV-induced collective behavior.

Conclusions:

• Core-shell SiO2-TiO2 microspheres offer significant advantages as model systems for active colloids.
• The developed technique provides a highly tunable platform for active matter research.
• These microspheres present a promising alternative to existing active colloid models, opening new research avenues.