Self-Propelled Janus Particles in a Ratchet: Numerical Simulations

Abstract

Brownian transport of self-propelled overdamped microswimmers (like Janus particles) in a two-dimensional periodically compartmentalized channel is numerically investigated for different compartment geometries, boundary collisional dynamics, and particle rotational diffusion. The resulting time-correlated active Brownian motion is subject to rectification in the presence of spatial asymmetry. We prove that ratcheting of Janus particles can be orders of magnitude stronger than for ordinary thermal potential ratchets and thus experimentally accessible. In particular, autonomous pumping of a large mixture of passive particles can be induced by just adding a small fraction of Janus particles.

Modeling crawling cell movement on soft engineered substrates

“…inside blood vessels or tissue) has inspired the studies of microswimmers moving through array of obstacles, 20 for the purpose of sorting and separation, 21 for rectication in ratchet-like channels or pumping uid. 22 This task is more complex for crawling cells. To emphasize the usefulness of our approach, we discuss cell motion on so synthetic substrates, where the focus lies on substrates with engineered elastic properties.…”

Dynamics of self-propelled particles under strong confinement

“…When the persistence length of active motion becomes comparable to the mean free path, uniquely active effects arise that transcend the thermodynamically allowed behaviors of equilibrium systems, including giant number fluctuations and spontaneous flow [3,14,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Importantly, a sufficient active persistence length is the only requirement for macroscopic manifestations of activity, as revealed by athermal phase separation of nonaligning, repulsive self-propelled particles [31][32][33][34][35][36][37][38][39][40][41].When boundaries and obstacles are patterned on the scale of the active correlation length, they dramatically alter the dynamics of the system, and striking macroscopic properties emerge [42][43][44][45][46][47][48][49]; for example, ratchets and funnels drive spontaneous flow in active fluids [42][43][44][45][46]. This effect has been used to direct bacterial motion [50] and harness bacterial power to propel microscopic gears …”

The Transport Performance of Feedback Coupled Brownian Ratchets

“…In recent years, the directed transport properties of Brownian ratchets attract the widespread attention of scholars [1,2] Only when the systems meet the spatio-temporal symmetry-breaking feature can produce the directed transport. The Brownian ratchets satisfy this condition, and that can take advantage of noise as it converts random fluctuations into directed motion without external force [3][4][5] Some properties of directed transport can be obtained through this interesting phenomenon, such as the center-of-mass mean velocity, the energy conversion efficiency, etc.…”