Analysis of different self-propulsion types of oil droplets based on electrostatic interaction effects

Noguchi, Mika; Yamada, Masato; Sawada, Hideyuki

doi:10.1039/d2ra02076a

Cited by 2 publications

(2 citation statements)

References 32 publications

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“…Their complex structures and structural flexibilities have been explored as synthetic active materials, and they have biological characteristics that possess dynamic properties along with chemical reactivity. For example, biological cells [7][8][9], microorganisms [8,9], camphor [10][11][12], and self-propelled droplets [13][14][15][16][17][18][19][20][21][22][23][24] have mechanisms for converting chemical energy into kinetic energy. Droplets have been studied in many research fields, including physical chemistry, chemical engineering and fluid mechanics [25,26].…”

Section: Introductionmentioning

confidence: 99%

Analysis of convection flow of a self-propelled alcohol droplet in an exoskeleton frame

Suzuki,

Sawada

2024

Robomech J

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This study aims to analyze the convection flow of a self-propelled 1-pentanol droplet. The droplets move spontaneously when 1-pentanol droplets are dropped into an aqueous 1-pentanol solution. This self-propulsion is due to the interfacial tension gradient caused by the concentration differences. The shape of the droplet is closely related to its behavior because the shape of the droplet changes the interfacial tension gradient. In this study, an exoskeleton is used to fix the droplet shape. In our preliminary experiments, we observed Marangoni convection in droplets dropped in exoskeleton frames with boomerang and round holes. The results showed that a large difference in surface tension was necessary to control the self-propulsion of the 1-pentanol droplets. Herein, we prepared two exoskeletons with different holes, an elongated symmetrical elliptical shape, and an asymmetrical shape to fix the shape of the droplet. The droplets were then dropped into each exoskeleton, and the droplet behavior, Marangoni convection inside the droplet, and convection in the aqueous phase were analyzed. We found that the direction of the self-propulsion of the droplet was determined by these exoskeletons, particularly in the case of the asymmetrical exoskeleton, and the direction of self-propulsion was fixed in one direction. Marangoni convection was observed in the droplet from the direction of lower surface tension to that of higher surface tension. In the aqueous phase, two convections were generated from the aqueous phase to the droplet because of the diffusion of 1-pentanol. In particular, when an asymmetrical exoskeleton was used, two convections of different sizes and velocities were observed in the aqueous phase. Based on these experimental results, the relationship between droplet behavior and convection is discussed.

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Section: Introductionmentioning

confidence: 99%

Analysis of convection flow of a self-propelled alcohol droplet in an exoskeleton frame

Suzuki,

Sawada

2024

Robomech J

Self Cite

View full text Add to dashboard Cite

show abstract

“…Their complex structures and structural flexibility have been explored as synthetic active materials, and they have biological characteristics that possess dynamic properties along with chemical reactivity. For example, biological cells [7][8][9], microorganisms [8,9], camphor [10][11][12], and self-propelled droplets [13][14][15][16][17][18][19][20][21][22][23][24] have mechanisms to convert chemical energy to kinetic energy. Droplets have been studied in a variety of areas, such as physical chemistry, chemical engineering, fluid mechanics [25].…”

mentioning

confidence: 99%

Analysis of self-propulsion of alcohol droplets under the effect of surface tension differences and convection flow

Suzuki,

Sawada

2023

Preprint

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This study aims to control the self-propulsion of 1-pentanol droplets. When 1-pentanol droplets are dropped in an aqueous 1-pentanol solution, droplets move spontaneously. This self-propulsion is due to interfacial tension gradient caused by concentration differences. The shape of the droplet is deeply related to droplet behavior because the shape of the droplet changes the interfacial tension gradient. In this study, an exoskeleton is introduced to fix the droplet shape. In our preliminary experiments, we observed Marangoni convection in droplets dropped in exoskeleton frames with boomerang and round shapes holes. The results showed that a large surface tension difference was necessary to control the self-propulsion of 1-pentanol droplets. In this study, we prepared two exoskeletons having different holes, which have an elongated symmetrical elliptical shape and an asymmetrical shape to fix the shape of the droplet. Then, we dropped droplets into each exoskeleton, and observed the droplet behavior, Marangoni convection inside the droplet, and the convection in the aqueous phase. We found that the direction of self-propulsion of the droplet was determined by these exoskeletons, especially in the case of the asymmetrical exoskeleton, and the direction of self-propulsion was fixed in one direction. Marangoni convection was observed in the droplet from the direction of lower surface tension to that of higher surface tension. In the aqueous phase, two convections were generated from the aqueous phase to the droplet because of the diffusion of 1-pentanol. Especially, when an asymmetrical exoskeleton was used, two convections with different sizes and velocities in aqueous phase were observed. From these experimental results, the relationship between droplet behavior and convection will be discussed.

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Analysis of different self-propulsion types of oil droplets based on electrostatic interaction effects

Abstract: We found that the correlated motion of two oil droplets was classified into three self-propelled motions (follow-up motion, parallel motion, and repulsive motion) depending on the pH of the aqueous solution.

Cited by 2 publications

References 32 publications

Analysis of convection flow of a self-propelled alcohol droplet in an exoskeleton frame

Analysis of convection flow of a self-propelled alcohol droplet in an exoskeleton frame

Analysis of self-propulsion of alcohol droplets under the effect of surface tension differences and convection flow

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