Self-Rotation-Induced Propulsion of a Leidenfrost Drop on a Ratchet

Mrinal, Manjarik; Wang, Xiang; Luo, Cheng

doi:10.1021/acs.langmuir.7b01420

Cited by 34 publications

(19 citation statements)

References 19 publications

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“…Subsequently, the values of λ are 2.5 mm and 1.5 mm, respectively, for water and IPA. According to Relation (12), with t ~1 mm and g = 9.8 m/s 2 , ejection speeds of both water and IPA drops have the order of 10 cm/s, which is in the same order as those reported on ratchets 17 – 19 , 29 . If t is an order higher than 1 mm, then, by Relation (12), the ejection speeds should be an order lower than 10 cm/s.…”

Section: Ejection Speed and Moving Distancesupporting

confidence: 63%

“…A Leidenfrost drop has a directional movement on a ratchet, due to the propulsion of the ratchet’s reaction forces that are induced by self-rotation of the drop 29 . The driving mechanism is different here.…”

Section: Moving Conditionsmentioning

confidence: 99%

“…This temperature difference results in a gradient of surface tension, generating the Marangoni flow that circulates inside the drop 30 , 35 . For both water and IPA, the flow speed has an order of 10 cm/s 4 , 29 . Given that an ejected drop’s center of mass has a translational speed with this order as well, the resultant speed of a point in the drop, u 0 , should also have an order of 10 cm/s.…”

Section: Effects Of Dynamic and Friction Forcesmentioning

confidence: 99%

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Self-propulsion of Leidenfrost Drops between Non-Parallel Structures

Luo

Mrinal

Wang

2017

Sci Rep

Self Cite

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In this work, we explored self-propulsion of a Leidenfrost drop between non-parallel structures. A theoretical model was first developed to determine conditions for liquid drops to start moving away from the corner of two non-parallel plates. These conditions were then simplified for the case of a Leidenfrost drop. Furthermore, ejection speeds and travel distances of Leidenfrost drops were derived using a scaling law. Subsequently, the theoretical models were validated by experiments. Finally, three new devices have been developed to manipulate Leidenfrost drops in different ways.

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Section: Ejection Speed and Moving Distancesupporting

confidence: 63%

Section: Moving Conditionsmentioning

confidence: 99%

Section: Effects Of Dynamic and Friction Forcesmentioning

confidence: 99%

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Self-propulsion of Leidenfrost Drops between Non-Parallel Structures

Luo

Mrinal

Wang

2017

Sci Rep

Self Cite

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“…In the literature, several mechanisms have been suggested to explain the self-propulsion of droplets due to substrate asymmetry, such as a jet-thrust effect [13], thermal creep flows [15], temperature-difference-induced Marangoni flows [16], and vapor rectification by the substrate geometry [9,10,12]. However, previous experimental [12,17,18] and numerical [10][11][12]17,18] works have demonstrated that the viscous-stress-induced propulsion due to vapor rectification is dominant.…”

Section: B the Model For Droplet Motion Driven By The Ratchet Portiomentioning

confidence: 99%

“…The use of such locally symmetric tooth profile negates the effect of any gradients induced due to thermal creep or Marangoni flows. Although Marangoni-driven flows have also been highlighted as a possible self-propulsion mechanism [16,19], recent studies have shown that internal flows homogenize the temperature in the drop [20]. Therefore, rotation due to Marangoni flows might be present but has a marginal role in self-propulsion.…”

Section: B the Model For Droplet Motion Driven By The Ratchet Portiomentioning

confidence: 99%

Low-Friction Self-Centering Droplet Propulsion and Transport Using a Leidenfrost Herringbone-Ratchet Structure

et al. 2019

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A fundamental limitation to the ability to transport sessile droplets is frictional forces arising from surface adhesion. This can be overcome by using the Leidenfrost effect on a heated substrate to levitate the droplet on a cushion of vapor. By structuring the surface under the droplet, the flow of vapor below the droplet can be controlled and this can be used to induce preferential droplet propulsion in a particular direction. However, while propulsion can be induced, the dramatic reduction in frictional forces leads to instability and it is difficult to control droplet motion when transporting droplets along a defined path. Here, we present a self-propulsion and self-centering concept using the principles of negative feedback to enable a droplet to be transported along a defined path. In our implementation, we use a combined herringbone and ratchet design, which provides the ability to control droplet position without compromising on speed. This intrinsic self-centering and correction via negative feedback offers the potential to design paths and tracks for droplets to follow, without the need for walls.

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Omni‐Liquid Droplet Manipulation Platform

Guo

Wang

Sun

et al. 2019

Adv Materials Inter

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Droplet manipulation is of importance in a wide range of applications in biomedicine, chemical analysis, and synthesis, among other fields. Over the past decade, extensive efforts are made to develop different strategies of transporting droplets by using various external stimuli. However, these methods could fail to manipulate some complex liquids with a low surface tension, high viscosity, or corrosivity. Herein, a magnetic digital microfluidics platform (MDMP) that is capable of manipulating almost all liquid droplets is described. The MDMP is designed by combining a magnet‐controlled deformable substrate and a slippery liquid‐infused surface. Such a structure allows creating a site‐specific gravitational potential gradient to propel droplets under different conditions. It is demonstrated that this MDMP can rapidly and reversibly transport various liquids for specimen sorting, chemical reactions, and accelerating mixing. It is envisioned that this universal droplet manipulation device will lay the foundation to achieve a wide variety of autonomous open channel fluidic device applications.

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Self-Rotation-Induced Propulsion of a Leidenfrost Drop on a Ratchet

Cited by 34 publications

References 19 publications

Self-propulsion of Leidenfrost Drops between Non-Parallel Structures

Self-propulsion of Leidenfrost Drops between Non-Parallel Structures

Low-Friction Self-Centering Droplet Propulsion and Transport Using a Leidenfrost Herringbone-Ratchet Structure

Omni‐Liquid Droplet Manipulation Platform

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