The role of particle shape in active depletion

Harder, J.M.; Mallory, S. A.; Tung, Clarion; Valeriani, Chantal; Cacciuto, Angelo

doi:10.1063/1.4900720

Cited by 81 publications

(94 citation statements)

References 32 publications

(36 reference statements)

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“…(In analogy with a potential of mean force for equilibrium systems, u ⌧,F (r) can be interpreted as the interaction potential necessary to generate in the undriven system the r-statistics of the driven system. 34 ) As illustrated in Figure 4a, the associated forces are largely attractive and are consistent with the observed segregation. The strength and range of attraction increase with increasing period and amplitude.…”

supporting

confidence: 66%

Exploiting non-equilibrium phase separation for self-assembly

et al. 2016

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Demixing can occur in systems of two or more particle species that experience different driving forces, e.g., mixtures of self-propelled active particles or of oppositely charged colloids subject to an electric field. Here we show with macroscopic experiments and computer simulations that the forces underlying such non-equilibrium segregation can be used to control the self-assembly of particles that lack attractive interactions. We demonstrate that, depending on the direction, amplitude and frequency of a periodic external force acting on one particle species, the structures formed by a second, undriven species can range from compact clusters to elongated, string-like patterns.

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confidence: 66%

Exploiting non-equilibrium phase separation for self-assembly

et al. 2016

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“…(16) are different from those found in the present treatment, based on the Fox approximation, even in the small τ (α) limit, given by Eq. (18). This observation makes sense regarding the nature of the derivation in Appendix A, whereas the UCNA becomes uncontrolled when more than one time scale is involved.…”

Section: A Fox's Approximation For Two Oscillatorsmentioning

confidence: 99%

“…On the other hand, active dopants with a short persistence length were reported to aggregate in cages [14]. On immersing large colloids into a bath * rene.wittmann@unifr.ch of smaller active colloids, the former effectively are rendered active, which becomes manifest through activity-enhanced diffusivities [15,16] and depletion forces [8,[17][18][19]. Employing shape-anisotropic colloids [19][20][21] or manufacturing activity gradients [22], these effects can be used to generate directed motion of the colloids.…”

Section: Introductionmentioning

confidence: 99%

Effective equilibrium states in mixtures of active particles driven by colored noise

et al. 2018

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We consider the steady-state behavior of pairs of active particles having different persistence times and diffusivities. To this purpose we employ the active Ornstein-Uhlenbeck model, where the particles are driven by colored noises with exponential correlation functions whose intensities and correlation times vary from species to species. By extending Fox's theory to many components, we derive by functional calculus an approximate Fokker-Planck equation for the configurational distribution function of the system. After illustrating the predicted distribution in the solvable case of two particles interacting via a harmonic potential, we consider systems of particles repelling through inverse power-law potentials. We compare the analytic predictions to computer simulations for such soft-repulsive interactions in one dimension and show that at linear order in the persistence times the theory is satisfactory. This work provides the toolbox to qualitatively describe many-body phenomena, such as demixing and depletion, by means of effective pair potentials.

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“…Instead, this effect, added to the peculiar non-equilibrium features of the dynamics of the self-propelled particles, generates an effective attractive or repulsive interaction which depends, e.g. on the shape of the passive particles, magnitude of the velocity of the active particles, ratio size between the passive colloids and active particles, and density [21][22][23]. In spite of its distinct nature, we follow the literature and still name here the effective interaction between passive objects in a bath of active particles as depletion interaction, and also name the force on the passive objects due to the active particles as depletion force.…”

Section: Introductionmentioning

confidence: 99%

Depletion forces on circular and elliptical obstacles induced by active matter

et al. 2016

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Depletion forces exerted by self-propelled particles on circular and elliptical passive objects are studied using numerical simulations. We show that a bath of active particles can induce repulsive and attractive forces which are sensitive to the shape and orientation of the passive objects (either horizontal or vertical ellipses). The resultant force on the passive objects due to the active particles is studied as a function of the shape and orientation of the passive objects, magnitude of the angular noise, distance between the passive objects. By increasing the distance between obstacles the magnitude of the repulsive depletion force increases, as long as such a distance is less than one active particle diameter. For longer distances, the magnitude of the force always decrease with increasing distance. We also found that attractive forces may arise for vertical ellipses at high enough area fraction.

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The role of particle shape in active depletion

Cited by 81 publications

References 32 publications

Exploiting non-equilibrium phase separation for self-assembly

Exploiting non-equilibrium phase separation for self-assembly

Effective equilibrium states in mixtures of active particles driven by colored noise

Depletion forces on circular and elliptical obstacles induced by active matter

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