Amoeboid Swimming: A Generic Self-Propulsion of Cells in Fluids by Means of Membrane Deformations

Farutin, Alexander; Rafaı̈, Salima; Dysthe, Dag Kristian; Duperray, Alain; Peyla, Philippe; Misbah, Chaouqi

doi:10.1103/physrevlett.111.228102

Cited by 70 publications

(93 citation statements)

References 24 publications

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“…According to Purcell's theorem [25], this cyclic motion should not be reversible in time owing to the invariance of the Stokes equations upon time reversal. Based on our first study on amoeboid motion [33] we shall make a simple choice for time dependence…”

Section: B the Choice Of The Active Forcesmentioning

confidence: 99%

“…Several models of directed self-propulsion by large shape deformation have been explored in the literature [26][27][28][29][30][31][32][33][34]. In two recent studies we introduced a model in which [33,34] the swimmer is considered as made of an inextensible membrane enclosing a constant volume of liquid and exerting a set of normal forces leading to deformations of the swimmer and to propulsion.…”

Section: Introductionmentioning

confidence: 99%

“…In two recent studies we introduced a model in which [33,34] the swimmer is considered as made of an inextensible membrane enclosing a constant volume of liquid and exerting a set of normal forces leading to deformations of the swimmer and to propulsion. The first study [33] dealt with purely unconfined three dimensional (3D) geometry; the more recent work was dedicated to a confined swimmer in two dimensions (2D) [34], a situation revealing several puzzling phenomena which we will look at later. Here we report on several new issues emerging for a confined amoeboid swimmer.…”

Section: Introductionmentioning

confidence: 99%

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Amoeboid swimming in a channel

Farutin

et al. 2016

Soft Matter

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Several micro-organisms, such as bacteria, algae, or spermatozoa, use flagellar or ciliary activity to swim in a fluid, while many other micro-organisms instead use ample shape deformation, described as amoeboid, to propel themselves by either crawling on a substrate or swimming. Many eukaryotic cells were believed to require an underlying substratum to migrate (crawl) by using membrane deformation (like blebbing or generation of lamellipodia) but there is now increasing evidence that a large variety of cells (including those of the immune system) can migrate without the assistance of focal adhesion, allowing them to swim as efficiently as they can crawl. This paper details the analysis of amoeboid swimming in a confined fluid by modeling the swimmer as an inextensible membrane deploying local active forces (with zero total force and torque). The swimmer displays a rich behavior: it may settle into a straight trajectory in the channel or navigate from one wall to the other depending on its confinement. The nature of the swimmer is also found to be affected by confinement: the swimmer can behave, on the average over one swimming cycle, as a pusher at low confinement, and becomes a puller at higher confinement, or vice versa. The swimmer's nature is thus not an intrinsic property. The scaling of the swimmer velocity V with the force amplitude A is analyzed in detail showing that at small enough A, V ∼ A 2 /η 2 (where η is the viscosity of the ambient fluid), whereas at large enough A, V is independent of the force and is determined solely by the stroke cycle frequency and swimmer size. This finding starkly contrasts with currently known results found from swimming models where motion is based on ciliary and flagellar activity, where V ∼ A/η. To conclude, two definitions of efficiency as put forward in the literature are analyzed with distinct outcomes. We find that one type of efficiency has an optimum as a function of confinement while the other does not. Future perspectives are outlined.

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Section: B the Choice Of The Active Forcesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Amoeboid swimming in a channel

Farutin

et al. 2016

Soft Matter

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“…Comprehensive studies aim to identify the efficient strategies for small scale displacement in liquids [1][2][3][4][5][6][7], which can possibly be exploited for the conception of synthetic microswimmers. Sticking to the strict definition of swimming as performing a displacement induced by body deformation, quite a few realizations of synthetic microswimmers can be found in literature [8][9][10][11][12].…”

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confidence: 99%

Buckling Instability Causes Inertial Thrust for Spherical Swimmers at All Scales

et al. 2017

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Microswimmers, and among them aspirant microrobots, generally have to cope with flows where viscous forces are dominant, characterized by a low Reynolds number (Re). This implies constraints on the possible sequences of body motion, which have to be nonreciprocal. Furthermore, the presence of a strong drag limits the range of resulting velocities. Here, we propose a swimming mechanism, which uses the buckling instability triggered by pressure waves to propel a spherical, hollow shell. With a macroscopic experimental model, we show that a net displacement is produced at all Re regimes. An optimal displacement caused by non-trivial history effects is reached at intermediate Re. We show that, due to the fast activation induced by the instability, this regime is reachable by microscopic shells. The rapid dynamics would also allow high frequency excitation with standard traveling ultrasonic waves. Scale considerations predict a swimming velocity of order 1 cm/s for a remote-controlled microrobot, a suitable value for biological applications such as drug delivery.Besides their playful aspect, artificial microswimmers present undeniable fundamental and practical interests, mostly driven by a constant race toward increasing miniaturization with potential applications such as targeted drug delivery. Comprehensive studies aim to identify the efficient strategies for small scale displacement in liquids [1][2][3][4][5][6][7], which can possibly be exploited for the conception of synthetic microswimmers. Sticking to the strict definition of swimming as performing a displacement induced by body deformation, quite a few realizations of synthetic microswimmers can be found in literature [8][9][10][11][12]. A growing attention toward the simplicity of their fabrication [13][14][15] opens possibilities for transfer in the industrial arena. The two main external sources of power are magnetic [10,11,13] and acoustic [12,14,15] fields, which are probably more suitable for medical applications and less expensive. The major conceptual difficulty lies in the low Reynolds flows usually associated with microscopic scales; the scallop theorem [16] then imposes that a non zero displacement may only occur via a nonreciprocal succession of shapes. Except in chiral systems [10,11], this necessary condition requires at least two degrees of freedom, which commonly implies two control parameters. Such heavy double steering could indeed be bypassed if flow rates can be rendered high enough so that inertia cannot be neglected anymore, or if any hysteresis in the deformation "naturally" prevents reciprocity.We suggest fulfilling these two conditions together with simple spherical colloidal shells full of air that are microscopic objects quite easy to manufacture [17,18]. Deflation from a spherical geometry occurs via buckling, which is a subcritical instability, likely to provide both swiftness and hysteresis during a deflation-re-inflation cycle driven by a single scalar control parameter : pressure. We investigate the swimming that results from t...

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“…90 The immersed boundary method is especially suited for objects immersed in a single fluid, e.g., for vesicles or for swimming deformable bodies. 92 For crawling cells, however, the motility-induced viscous drag outside is typically small compared with the substrate-based propulsion forces and the viscous dissipation inside the cell.…”

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confidence: 99%

Computational approaches to substrate-based cell motility

Ziebert

Aranson

2016

npj Comput Mater

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Substrate-based crawling motility of eukaryotic cells is essential for many biological functions, both in developing and mature organisms. Motility dysfunctions are involved in several life-threatening pathologies such as cancer and metastasis. Motile cells are also a natural realisation of active, self-propelled 'particles', a popular research topic in nonequilibrium physics. Finally, from the materials perspective, assemblies of motile cells and evolving tissues constitute a class of adaptive self-healing materials that respond to the topography, elasticity and surface chemistry of the environment and react to external stimuli. Although a comprehensive understanding of substrate-based cell motility remains elusive, progress has been achieved recently in its modelling on the whole-cell level. Here we survey the most recent advances in computational approaches to cell movement and demonstrate how these models improve our understanding of complex self-organised systems such as living cells.

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Amoeboid Swimming: A Generic Self-Propulsion of Cells in Fluids by Means of Membrane Deformations

Cited by 70 publications

References 24 publications

Amoeboid swimming in a channel

Amoeboid swimming in a channel

Buckling Instability Causes Inertial Thrust for Spherical Swimmers at All Scales

Computational approaches to substrate-based cell motility

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