Active Propulsion of Patchy Ellipsoids

Active colloids are a class of microparticles that ‘propel’ through fluids by breaking the symmetry of the force distribution on their surfaces. Our ability to direct these particles along complex trajectories in 3D space requires strategies to encode the desired forces and torques at the single particle level. Here, we show that ellipsoids with metal patches can be directed along non-linear trajectories when powered remotely by alternating current (AC) electric fields. In particular, we demonstrate that the trajectory of patchy ellipsoid can be manipulated by the symmetry of metal patch and the aspect ratio of ellipsoids. We show that the properties of the particle trajectory are tunable by applied field strength, frequency, and added electrolyte. The observed motion trajectories of the particles include cylindrical helices, non-linear shuttling, and self-repeating periodic motion along curvilinear paths. We further demonstrate the critical role of non-linear trajectory of the particle in enhancing its transport through porous media with important implications for the design of microrobots that can navigate complex environments.