Self-propelled motion of a fluid droplet under chemical reaction

Yabunaka, Shunsuke; Ohta, Takao; Yoshinaga, Natsuhiko

doi:10.1063/1.3685805

Cited by 62 publications

(106 citation statements)

References 26 publications

(24 reference statements)

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“…By such a procedure, we can derive the normal form of the bifurcation [27]. The expansion for the shape or deformation is rather complicated for higher orders of .…”

Section: -3mentioning

confidence: 99%

Spontaneous motion of an elliptic camphor particle

2013

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The coupling between deformation and motion in a self-propelled system has attracted broader interest. In the present study, we consider an elliptic camphor particle for investigating the effect of particle shape on spontaneous motion. It is concluded that the symmetric spatial distribution of camphor molecules at the water surface becomes unstable first in the direction of a short axis, which induces the camphor disk motion in this direction. Experimental results also support the theoretical analysis. From the present results, we suggest that when an elliptic particle supplies surface-active molecules to the water surface, the particle can exhibit translational motion only in the short-axis direction. Spontaneous motion in nonequilibrium systems has long attracted the interest of scientists because it is related to the motion of living organisms. In particular, the coupling between deformation and spontaneous motion has been actively investigated and several important and interesting studies, both experimental and theoretical, have been reported. For example, Ohta et al. proposed a generic model for the coupling between deformation and spontaneous motion by analyzing such coupling from the viewpoint of the bifurcation theory of dynamical systems [1][2][3]. Teramoto et al. studied the coupling between deformation and motion in pulse propagation in a reaction-diffusion system [4]. In experiments, cell motion is analyzed in relation to cell shape [5][6][7], and mathematical models have also been proposed for such cell deformation [8,9].For investigating the coupling between motion and deformation, one approach is to decouple them; i.e., we consider the effect of particle shape on motion. For this purpose, we chose a camphor-water system, in which a camphor particle exhibits spontaneous motion but not deformation. The camphor-water system was first reported in the 19th century [10,11]. As a camphor particle is placed on pure water, it exhibits spontaneous motion. The mechanism of the motion is briefly described as follows [12,13]: Camphor molecules escape from the camphor particle to the water surface. Since camphor has a surface activity, the camphor molecules at the water surface reduce the surface tension. It should be noted that the camphor molecules sublimate to the air, so that the profile of the surface concentration of camphor molecules at the water surface can reach a steady state. If the camphor particle is circular and does not move, the profile of the surface concentration of camphor molecules should be symmetric with respect to the center of the camphor particle. However, it is known that such a steady state can become unstable by an infinitesimal fluctuation. In such a case, motion in a certain direction at a constant velocity is stabilized and realized. Consequently, the profile of * Corresponding author: kitahata@physics.s.chiba-u.ac.jp the surface concentration becomes asymmetric [14][15][16]. This camphor-water system has attracted attention since it exhibits interesting and complicated phenomena ...

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“…By such a procedure, we can derive the normal form of the bifurcation [27]. The expansion for the shape or deformation is rather complicated for higher orders of .…”

Section: -3mentioning

confidence: 99%

Spontaneous motion of an elliptic camphor particle

2013

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“…The latter often take the form of Janus-like colloids [12], named after the twofaced Roman god, because their motion originates from the asymmetry of their surface properties [9,10,13]. An alternative design of artificial swimmers consists of active droplets, either on interfaces [14,15] or in bulk fluid [16][17][18][19]. Droplets are particularly interesting systems since they are extensively used in microfluidic devices as (bio-)chemical reactors [20,21].…”

Section: Pacs Numbersmentioning

confidence: 99%

Self-Propulsion of Pure Water Droplets by Spontaneous Marangoni-Stress-Driven Motion

et al. 2014

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We report spontaneous motion in a fully bio-compatible system consisting of pure water droplets in an oil-surfactant medium of squalane and monoolein. Water from the droplet is solubilized by the reverse micellar solution, creating a concentration gradient of swollen reverse micelles around each droplet. The strong advection and weak diffusion conditions allow for the first experimental realization of spontaneous motion in a system of isotropic particles at sufficiently large Péclet number according to a straightforward generalization of a recently proposed mechanism [1, 2] Experiments with a highly concentrated solution of salt instead of water, and tetradecane instead of squalane, confirm the above mechanism. The present swimming droplets are able to carry external bodies such as large colloids, salt crystals, and even cells.

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“…Spontaneous motion driven by inhomogeneity in interfacial tension is an area of study relating to active matter. [5][6][7][8][9][10][11][12][13][14][15][16] For example, alcohol droplets placed on water move spontaneously while exhibiting deformations to their shape. 17,18 Since such systems are relatively simple, it is possible to perform experiments under a broad parameter space; therefore, such a setting provides a preferable experimental framework for investigations of general aspects.…”

Section: Introductionmentioning

confidence: 99%

Mathematical model for self-propelled droplets driven by interfacial tension

Nagai

Tachibana

Tobe

et al. 2016

The Journal of Chemical Physics

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Articles you may be interested inNumerical study on the effects of non-dimensional parameters on drop-on-demand droplet formation dynamics and printability range in the up-scaled model Phys. Fluids 24, 082103 (2012) We propose a model for the spontaneous motion of a droplet induced by inhomogeneity in interfacial tension. The model is derived from a variation of the Lagrangian of the system and we use a time-discretized Morse flow scheme to perform its numerical simulations. Our model can naturally simulate the dynamics of a single droplet, as well as that of multiple droplets, where the volume of each droplet is conserved. We reproduced the ballistic motion and fission of a droplet, and the collision of two droplets was also examined numerically. C 2016 AIP Publishing LLC. [http://dx

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Self-propelled motion of a fluid droplet under chemical reaction

Cited by 62 publications

References 26 publications

Spontaneous motion of an elliptic camphor particle

Spontaneous motion of an elliptic camphor particle

Self-Propulsion of Pure Water Droplets by Spontaneous Marangoni-Stress-Driven Motion

Mathematical model for self-propelled droplets driven by interfacial tension

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