Fig. 1: Individual particle dynamics of pear-shaped Quincke rollers.
From: Reconfigurable emergent patterns in active chiral fluids
a Schematics of the experiment: pear-shaped particles are confined in a cylindrical well. A uniform DC electric field is applied normal to the bottom surface of the cell. b Rolling velocity of the pear-shaped particles as a function of the electric field strength E. Shaded area is a crossover region between two different modes of particles rolling. The red dash line is a fit of the high field part of the curve to \(| v| \sim \sqrt{{(E/{E}_{{\rm{c}}})}^{2}-1}\) dependence typical for spherical rollers. Ec = 1.96 V μm−1. Insert, ∣v∣2 versus E2. Error bars are standard deviation of the absolute values of velocities. c Three rolling modes of a pear-shaped particle: α (θ > 0), β (θ = 0) and γ (θ < 0). Blue dash lines illustrate corresponding trajectories. d Trajectory curvature parameter, κ, as a function of the electric field strength. Two distinctive modes of rolling correspond to α mode-‘heads-out’ (κ < 0) and γ mode-‘heads-in’ (κ >  0) regimes of particles propulsion. e Time evolution of the mean square displacement of pear-shaped Quincke rollers shown for a set of driving electric field strengths. f Mean square angular displacements of pear-shaped rollers. In e–f black solid line has a slope of 1 and black dash lines have slopes of 2. In b, e–f area fractions of rollers are 0.001.
