Magnetically locked Janus particle clusters with orientation-dependent motion in AC electric fields

Area of Science:

• Physics, Materials Science, Nanotechnology

Background:

• Active particles, or micromotors, use local energy dissipation for locomotion at small scales.
• Particle trajectory is typically fixed by geometry and composition, limiting tunability.
• Conventional fabrication methods pose challenges for customizing micromotor movement.

Purpose of the Study:

• To develop a simple, bottom-up method for creating tunable micromotors.
• To assemble gold-coated polystyrene Janus particles into magnetically locked clusters.
• To investigate diverse locomotion trajectories of these clusters under AC electric fields.

Main Methods:

• Bottom-up magnetic assembly of gold-coated polystyrene Janus particles into clusters.
• Stimulation of assembled clusters using AC electric fields.
• Modeling the system using a simplified rigid beads model.

Main Results:

• Achieved magnetically assembled Janus particle clusters with tunable locomotion.
• Observed diverse trajectory modes including translational, rotational, trochoidal, helical, and orbital motion.
• Demonstrated qualitative agreement between experimental observations and theoretical models.

Conclusions:

• A facile and scalable method for creating micromotors with diverse, well-defined motions from discrete building blocks was developed.
• The orientation of particles within clusters dictates distinct locomotion modes.
• This approach offers a promising route for designing sophisticated micro-robots with controllable movement.