Manipulating chiral microswimmers in a channel

Abstract

We numerically simulate the diffusion of overdampd pointlike Janus particles along narrow two-dimensional periodically corrugated channels with reflecting walls. The self-propulsion velocity of the particle is assumed to rotate subject to an intrinsic bias modeled by a torque. Breaking the mirror symmetry of the channel with respect to its axis suffices to generate a directed particle flow with orientation and magnitude which depend on the channel geometry and the particle swimming properties. This means that chiral microswimmers drift autonomously along a narrow channel under more general asymmetry conditions than previously reported, a property of potential impact on their fabrication and technological applications.

Active Brownian motion in a narrow channel

“…The peak in the curvesv versus for > 1 and constant Ω reported in Fig. 6 can be interpreted in the same way [36].…”

“…The rectification power is proportional to (Ωτ θ ) 2 in the weak chirality regime, i.e., inverse proportional to D For an optimal value of Ω and low noise levels, the particle tends to accumulate against the walls [37,4], with tangential velocities close to ±v 0 . This is the condition of strong chirality, |Ω|τ θ 1, and low noise, v 0 |Ω|/D 0 1, where strong autonomous rectification was first reported [36]. Indeed, as the chiral radius exceeds the compartment dimensions, R Ω x L , a strongly chiral swimmer spends more time drifting between the upper and lower walls than sliding along them, thus weakening the boundary flows.…”

“…The dependence of η on the fluctuation parameters D 0 and D θ is illustrated in Fig. 7, adapeted from [36], and in particular in panel (a). The rectification power is proportional to (Ωτ θ ) 2 in the weak chirality regime, i.e., inverse proportional to D For an optimal value of Ω and low noise levels, the particle tends to accumulate against the walls [37,4], with tangential velocities close to ±v 0 .…”

“…[36] to study the net flow of a levogyre microswimmer with Ω > 0, confined to the periodic channel of boundaries,…”

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

“…The collection of bacteria is able to migrate against the funnel-shaped barriers by creating and maintaining a chemoattractant gradient [26]. Li and coworkers [29] manipulated transport of overdampd pointlike Janus particles in narrow two-dimensional corrugated channels. In addition, the chiral active particles can be rectified and sorted in complex and crowded environments [34,35].…”