Project Info

Active Motion of Colloids under AC Electric Fields

Ning Wu | mailto:ningwu@mines.edu

The objective of this collaborative proposal is to answer a fundamental question: how does the electrohydrodynamics (EHD) of asymmetric particle influence their active behavior ranging from single particle motion to small cluster formation to emergent collective dynamics? Our recent experiments revealed a new type of lateral motion for colloids under a perpendicular AC electric field. Although our results hold the promise for on-demand control of intelligent micro-machines, current electrokinetic theory cannot consistently explain them. Our flow tracing experiments strongly suggest an unbalanced EHD flow surrounding the particles. Therefore, we will perform experiments to elucidate the EHD propulsion mechanisms of dielectric particles at low frequency and probe a potentially new mechanism for their motion reversal at high frequency. We will also quantify the impacts of particle properties, field parameters, and solvent conditions that control the propulsion direction and speed of individual particles.

More Information

“Change the Collective Behaviors of Colloidal Motors by Tuning Electrohydrodynamic Flow at the Subparticle Level”, X Yang, N Wu, Langmuir 34 (3), 952-960 (2018)

“Inducing Propulsion of Colloidal Dimers by Breaking the Symmetry in Electrohydrodynamic Flow”, F Ma, X Yang, H Zhao, N Wu, Physical Review Letters 115, 208302 (2015)

“Electric-field–induced assembly and propulsion of chiral colloidal clusters”, F Ma, S Wang, DT Wu, N Wu, Proceedings of the National Academy of Sciences 112 (20), 6307–6312 (2015)

Grand Engineering: –