Unidirectional Rotation And Diffusion Of Soft Vesicles/rigid Circles Driven By Chiral Active Particles

Active matter systems move actively by gaining energy from an external source under non-equilibrium conditions.Competition between random fluctuations and self-propulsion makes them enter a state far from equilibrium.Therefore,their behavior can only be explained and understood within the framework of unbalanced statistical physics,and the further study of them can also provide an ideal model system.In the biological world,many cells play the role of self-propelled particles,such as some eukaryotic cells,which can move directionally in a fluid environment in different ways.Active particles with suitably designed constructions are able to convert energy into desired control of function,which have wide potential applications in a diversity of fields,such as physics,chemistry and medicine.By employing the overdamped Langevin dynamics simulations,we explore the dynamics of two-dimensional soft vesicles/rigid circles filled with chiral active particles,and the unidirectional rotation is observed.For soft vesicles,rotational angular velocity of vesicle depends mainly on the angular velocity(ω)and area fraction(p)of chiral active particles,and there exists an optimal value of ω at which the rotational angular velocity of vesicle takes its maximal value.The shape properties of vesicle are abundant,which mainly rely on the area fraction and angular velocity of chiral active particles as well as the size of vesicle(L).Interestingly,at low concentrations the continuity of curvature is destroyed seriously by chiral active particles with large ω,and at high concentrations the chiral active particles cover the vesicle almost uniformly,resulting in fairly homogeneous curvature and nearly circular vesicle shape.For rigid circles,the rotational angular vecocity relies mainly on the length(1),number(nB),and tilt angle(y)of boards,and angular velocity(ω)and area fraction(p)of chiral active particles.In addition,the center-of-mass mean square displacement for soft vesicles or rigid circles is accompanied by oscillations at short timescales,and the oscillation period of diffusion is consistent with the rotation period of chiral active particles.Studying the non-equilibrium dynamics of self-propelled particles,we can understand interesting natural phenomena from macro to micro such as bird groups,colonies,tissue repair and cytoskeleton.Our research provides an optimization for nanofabricated devices that can be driven in a unidirectional rotation by chiral active particles.