Collective dynamics of self-propelled sphere-dimer motors

Abstract

The collective dynamics of ensembles of chemically powered sphere dimer motors is investigated. Sphere dimers are self-propelled nanomotors built from linked catalytic and noncatalytic spheres. They consume fuel in the environment and utilize the resulting self-generated concentration gradients to produce directed motion along their internuclear axes. In collections of such motors, the individual motors interact through forces that arise from concentration gradients, hydrodynamic coupling, and direct intermolecular forces. Under nonequilibrium conditions it is found that the sphere dimer motors self-assemble into transient aggregates with distinctive structural correlations and exhibit swarming where the aggregates propagate through the system. The mean square displacement of a dimer motor in the ensemble displays short-time ballistic and long-time diffusive regimes and, for ensembles containing many motors, an increasingly prominent intermediate regime. The self-diffusion coefficient of a motor in a many-motor system behaves differently from that of an isolated motor, and the decay of orientational correlations is a nonmonotonic function of the number of motors. The results presented here illustrate the phenomena to be expected in applications, such as cargo transport, where many motors may act in consort.

Hydrodynamic simulations of self-phoretic microswimmers

“…an external laser, which creates a local temperature gradient. The investigations performed by computer simulations have * Electronic address: mcyang@iphy.ac.cn † Electronic address: m.ripoll@fz-juelich.de mostly considered dimer structures composed of two connected beads instead of Janus particles [17][18][19][20]. This is motivated by the simplicity of the structure which can be approached by a two beads model.…”

Catalytically powered dynamic assembly of rod-shaped nanomotors and passive tracer particles

“…Hydrophobicity and hydrodynamic interactions can also drive the assembly of nanomotors (31,32). Although theoretical models and numerical simulations have furthered our understanding of these systems (33)(34)(35)(36)(37), there is still a lack of information on the pairwise interactions of particles that result in emergent behavior. Quantifying these interactions at the level of individual microparticles should lead to better understanding of active matter (whether it is composed of synthetic and biological micromotors) and may ultimately enable the prediction, design, and application of collective behavior.…”

Autonomous movement of a chemically powered vesicle

“…The solvent transport coefficient can be calculated analytically for MPC dynamics 15 , giving τ D ≈ 600 for vesicle with N v = 110. For short times (t τ D ) MSD is shown to exhibit ballistic regime 40 where ∆L 2 (t) ∼ V z 2 t 2 , while for long times t τ R it exhibits a linear behaviour as Fig.…”

“…For the other route the propulsion rely on asymmetric chemical reactivity instead of asymmetric conformational dynamics. The most widely studied example of this type of motors are bimetallic nanorods 10,11 , Janus particles 12 , sphere dimer motors [13][14][15] , polymers 16 The above cited example of physically asymmetric selfproplled objects assume that the particle shape is unchanged during the motion. However, in reality many self-propelled objects may change their shape depending on the velocity, environment or interaction with other objects.…”