Quincke rotation is defined as the spontaneous steady rotation of a dielectric particle immersed in a dielectric solvent under a steady and uniform electric field. Electro-hydrodynamically driven active particles based on Quincke rotation are a significant model system for emergent collective behavior in non-equilibrium colloidal systems. Quincke rollers are intrinsically nonmagnetic and therefore magnetic fields cannot be used to regulate their complex dynamics.
In a new report published in Science Advances, Ricardo Reyes Garza and a research team in applied physics, Aalto University School of Science, Finland, developed magnetic Quincke rollers via silica particles doped with superparamagnetic iron oxide nanoparticles. This magnetic nature allowed the application of external forces and torques that can be regulated at high space-time precision. Applications include tunable interparticle interactions with potential landscapes, and advanced programmable and teleoperated behaviors.
Active matter systems are based on many individual agents that absorb energy from their environment to convert it to mechanical forces and motion. Recently, researchers have shown increased attention to artificial active systems such as Janus particles, vibrated polar disks and Quincke rollers. Quincke rollers are significant due to their rich, collective dynamics and a range of emergent states observed with solid non-deformable Quincke rollers and deformable liquid droplets. The emergent states include polar liquids, vortices, and active emulsions of liquid rollers.
The dynamics of these states are fast and depend on the same electric field to influence Quincke rotation. Magnetic forces and torques can be applied to successfully regulate the dynamics of soft materials ranging from individual macromolecules to solid particles, and bulk liquids. They can be used to energize systems in the form of oscillating magnetic fields, to steer or activate passive particles.
This work detailed the development of broadly tunable Quincke rollers by using magnetic forces and torques. The system contained spherical silicon dioxide particles doped with superparamagnetic iron oxide nanoparticles immersed in a slightly conductive liquid medium, containing n-dodecane with sodium bis (2-ethylhexyl) sulfosuccinate.
2023-07-25 05:24:02
Original from phys.org
