Leveraging collective effects in externally driven colloidal suspensions: experiments and simulations

Driscoll, Michelle; Delmotte, Blaise

doi:10.1016/j.cocis.2018.10.002

Cited by 62 publications

(48 citation statements)

References 183 publications

(278 reference statements)

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“…Turbulent-like flows in bacteria and sperm suspensions [6][7][8][9], and phase synchronization between flagella [10] are illustrative examples in natural systems. Colloidal particles have been designed to mimic the behavior of natural systems at both the individual and collective level [11,12], and also to explore alternative ways to mix the surrounding fluid or to transport particles at low Reynolds number [13][14][15]. In particular, recent experiments and simulations have shown that suspensions of torque-driven particles above a floor could self-assemble into stable motile structures, called "critters", that have no analog in natural systems [16], see Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Hydrodynamically bound states of a pair of microrollers: A dynamical system insight

Delmotte

2019

Phys. Rev. Fluids

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Recent work has identified persistent cluster states which were shown to be assembled and held together by hydrodynamic interactions alone [Driscoll et al. (2017) Nature Physics, 13(4), 375]. These states were seen in systems of colloidal microrollers; microrollers are colloidal particles which rotate about an axis parallel to the floor and generate strong, slowly decaying, advective flows. To understand these bound states, we study a simple, yet rich, model system of two microrollers. Here we show that pairs of microrollers can exhibit hydrodynamic bound states whose nature depends on a dimensionless number, denoted B, that compares the relative strength of gravitational forces and external torques. Using a dynamical system framework, we characterize these various states in phase space and analyze the bifurcations of the system as B varies. In particular, we show that there is a critical value, B * , above which active flows can beat gravity and lead to stable motile orbiting, or "leapfrog", trajectories, reminiscent of the self-assembled motile structures, called "critters", observed by Driscoll et al. We identify the conditions for the emergence of these trajectories and study their basin of attraction. This work shows that a wide variety of stable bound states can be obtained with only two particles. Our results aid in understanding the mechanisms that lead to spontaneous self-assembly in hydrodynamic systems, such as microroller suspensions, as well as how to optimize these systems for particle transport. * blaise.delmotte@ladhyx.polytechnique.fr arXiv:1811.05168v4 [physics.flu-dyn]

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Section: Introductionmentioning

confidence: 99%

“…The physics of torque-driven colloidal particles (called microrotors) have recently attracted significant attention [13,15,17]. Microrotors can be driven with an external rotating magnetic field [16,18], or by using a Quincke-like instability under the action of an electric [19] or magnetic field [20].…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamically bound states of a pair of microrollers: A dynamical system insight

Delmotte

2019

Phys. Rev. Fluids

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“…The resulting overdamped dynamics can therefore be adequately described within the framework of linear hydrodynamics [93,94]. Accordingly, the translational velocity of the membrane particles V i is linearly coupled to the forces acting on their surfaces via the hydrodynamic mobility functions [95][96][97][98]. The latter are second-order tensors, which simply reduce to scalar quantities when considering motion in an unbounded medium and neglecting the fluid-mediated hydrodynamic interactions between the particles.…”

Section: System Setupmentioning

confidence: 99%

Theory of active particle penetration through a planar elastic membrane

et al. 2019

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With the rapid advent of biomedical and biotechnological innovations, a deep understanding of the nature of interaction between nanomaterials and cell membranes, tissues, and organs, has become increasingly important. Active penetration of nanoparticles through cell membranes is a fascinating phenomenon that may have important implications in various biomedical and clinical applications. Using a fully analytical theory supplemented by particle-based computer simulations, the penetration process of an active particle through a planar two-dimensional elastic membrane is studied. The membrane is modeled as a selfassembled sheet of particles, uniformly arranged on a square lattice. A coarse-grained model is introduced to describe the mutual interactions between the membrane particles. The active penetrating particle is assumed to interact sterically with the membrane particles. State diagrams are presented to fully characterize the system behavior as functions of the relevant control parameters governing the transition between different dynamical states. Three distinct scenarios are identified. These compromise trapping of the active particle, penetration through the membrane with subsequent self-healing, in addition to penetration with permanent disruption of the membrane. The latter scenario may be accompanied by a partial fragmentation of the membrane into bunches of isolated or clustered particles and creation of a hole of a size exceeding the interaction range of the membrane components. It is further demonstrated that the capability of penetration is strongly influenced by the size of the approaching particle relative to that of the membrane particles. Accordingly, active particles with larger size are more likely to remain trapped at the membrane for the same propulsion speed. Such behavior is in line with experimental observations. Our analytical theory is based on a combination of a perturbative expansion technique and a discrete-tocontinuum formulation. It well describes the system behavior in the small-deformation regime. Particularly, the theory allows to determine the membrane displacement of the particles in the trapping state. Our approach might be helpful for the prediction of the transition threshold between the trapping and penetration in real-space experiments involving motile swimming bacteria or artificial active particles.

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“…1 Introducing colloidal suspensions into such structures introduces an extra level of complexity, and is also of high technological relevance in filtration, separation, or assisted concentration of colloids. 2 Examples of this can be found in fields ranging from oil recovery 3 to food processing. 4 The interaction between channel walls and the (often charged) colloidal particles (CPs) initiates a range of multi-scale processes, 5 complicating the rational design of fluid processing and lab-on-chip devices.…”

Section: Introductionmentioning

confidence: 99%

Regulating the aggregation of colloidal particles in an electro-osmotic micropump

Zhang

Graaf²,

Faez³

2020

Soft Matter

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Leveraging collective effects in externally driven colloidal suspensions: experiments and simulations

Cited by 62 publications

References 183 publications

Hydrodynamically bound states of a pair of microrollers: A dynamical system insight

Hydrodynamically bound states of a pair of microrollers: A dynamical system insight

Theory of active particle penetration through a planar elastic membrane

Regulating the aggregation of colloidal particles in an electro-osmotic micropump

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