(255e) Active Particles Powered By Quincke Rotation Instability in a Bulk Fluid

Dielectric particles suspended in a weakly conducting fluid are known to spontaneously start rotating under the action of a sufficiently strong uniform DC electric field due to the Quincke rotation instability. This rotation can be converted into translation when the particles are placed near a surface providing useful model systems for active matter. Using a combination of numerical simulations and theoretical models, we demonstrate that it is possible to convert the spontaneous Quincke rotation into spontaneous translation even in the absence of surfaces by relying on geometrical asymmetry instead. The resulting novel type of active particle (i) is capable of autonomous self propulsion, i.e. the direction of propulsion is not set and controlled by an external field, (ii) does not require the presence of a surface and (iii) is amenable to theoretical analysis using first principles. Suspensions of randomly-shaped particles under Quincke rotation would thus be expected to perform collective motion by exploring the full three-dimensional space as the swimming direction is unspecified, thereby, opening doors to a potentially new type of active matter.