Colloidal squirmers in a nematic liquid crystal

The creation of tiny self-propelled particles is a subject of intense current interest, and control on their direction of motion is critical for applications. We show that metal-dielectric Janus particles in a nematic liquid crystal are self-propelled by converting the energy of an oscillating electric field. They behave like steerable active particles whose direction of motion can be dictated purely by varying the field amplitude and frequency. The underlying mechanism involves the contrasting electrostatic boundary condition, dielectric anisotropy and the defect structure of the liquid crystal. We show that the electrostatic force density around the particle is that of either a puller or pusher force dipole, causing the particle to swim. These findings open unexplored directions for the use of colloids and liquid crystals in controlled transport, assembly, and collective dynamics.

References:

Dinesh Kumar Sahu, Swapnil Kole, Sriram Ramaswamy and Surajit Dhara, Phys. Rev. Res. (Rapid Com.) 2, 032009(R) (2020), 

Dinesh Kumar Sahu and Surajit Dhara, Phys. Rev. Applied. 14, 034004 (2020)