Effects of hydrodynamic interactions on rectified transport of self-propelled particles

Abstract

Directed transport of self-propelled particles is numerically investigated in a three-dimensional asymmetric potential. Beside the steric repulsive forces, hydrodynamic interactions between particles have been taken into account in an approximate way. From numerical simulations, we find that hydrodynamic interactions can strongly affect the rectified transport of self-propelled particles. Hydrodynamic interactions enhance the performance of the rectified transport when particles can easily pass across the barrier of the potential, and reduce the rectified transport when particles are mainly trapped in the potential well.

Activated barrier crossing dynamics of a Janus particle carrying cargo

“…Thanks to selfpropulsion, Janus particles can diffuse orders of magnitude faster than a normal Brownian particles of the same size (e.g., a silica sphere of radius 2.13 mm, half-coated with 20 nm thick gold caps, diffuses 7.84 µm 2 per second when the particle is exposed to a laser pulse of intensity 161 nW per micro meter square , where as a silica sphere of the same size (without gold coating) has diffusivity of 0.03 µm 2 per second [10]). Transport properties of Janus particles are unusual as well as very interesting, e.g., they can exhibit autonomous motion when they encounter potential (due to interaction with substrate) or confinement of asymmetric and periodic nature [15][16][17][18], in some special non-equilibrium situations JPs can move opposite to the driving force [25], JPs can transiently drift towards the high fuel density or intense light [26][27][28][29]. All these features fascinate researchers to learn more precisely about motion of the particle so that they can be used in targeted drug delivery and other purposes in medical sciences.…”

Directed transport of a deformable particle in confined periodic structures

“…In general, ratchet effect can occur when system is out of thermodynamical equilibrium and the symmetries of the system are broken. Depending on the type of the nonequilibrium driving, ratchet devices fall into four categories : (1) rocking ratchet [12][13][14][15][16][17] in which the transient time asymmetry of the system is caused by the unbiased external force. (2) Flashing ratchet [18][19][20][21][22], where the asymmetric potential field of the particle randomly transfers between two or more states or adopts the time modulation of the potential to form a directed motion.…”

“…(3) Correlation ratchet [23][24][25][26][27][28] which mainly considers the influence of color noise on rectification. (4) Self-propelled ratchets [29][30][31][32][33][34][35][36][37][38][39][40][41], where active particles interact with an asymmetric substrate, and a net directed motion can arise even without external driving. In these ratchet systems, the nonequilibrium driving can break thermodynamical equilibrium and induce the directed transport.…”

Collective transport of polar active particles on the surface of a corrugated tube

“…The problem of rectifying motion in random environments is a long-standing issue, which has many theoretical and practical implications [37,38]. Active matter can be rectified on the asymmetric substrates without external driving, which may open a wealth of possibilities such as cargo transport, sorting, or micromachine construction [39][40][41][42][43][44][45]. Rectification of active matter confined to a surface has been mainly studied on planar surfaces.…”