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Barrio-Zhang H, Ruiz-Gutiérrez É, Orejon D, Wells GG, Ledesma-Aguilar R. Droplet motion driven by humidity gradients during evaporation and condensation. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2024; 47:32. [PMID: 38735905 PMCID: PMC11089009 DOI: 10.1140/epje/s10189-024-00426-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 04/15/2024] [Indexed: 05/14/2024]
Abstract
The motion of droplets on solid surfaces in response to an external gradient is a fundamental problem with a broad range of applications, including water harvesting, heat exchange, mixing and printing. Here we study the motion of droplets driven by a humidity gradient, i.e. a variation in concentration of their own vapour in the surrounding gas phase. Using lattice-Boltzmann simulations of a diffuse-interface hydrodynamic model to account for the liquid and gas phases, we demonstrate that the droplet migrates towards the region of higher vapour concentration. This effect holds in situations where the ambient gradient drives either the evaporation or the condensation of the droplet, or both simultaneously. We identify two main mechanisms responsible for the observed motion: a difference in surface wettability, which we measure in terms of the Young stress, and a variation in surface tension, which drives a Marangoni flow. Our results are relevant in advancing our knowledge of the interplay between gas and liquid phases out of thermodynamic equilibrium, as well as for applications involving the control of droplet motion.
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Affiliation(s)
- Hernán Barrio-Zhang
- Institute for Multiscale Thermofluids, School of Engineering, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh, EH9 3FB, UK.
| | - Élfego Ruiz-Gutiérrez
- School of Engineering, Newcastle University, Claremont Road, Newcastle upon Tyne, NE1 7RU, UK
| | - Daniel Orejon
- Institute for Multiscale Thermofluids, School of Engineering, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh, EH9 3FB, UK
| | - Gary G Wells
- Institute for Multiscale Thermofluids, School of Engineering, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh, EH9 3FB, UK
| | - Rodrigo Ledesma-Aguilar
- Institute for Multiscale Thermofluids, School of Engineering, University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh, EH9 3FB, UK
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Li W, Li D, Zhu X, Ye D, Yang Y, Wang H, Chen R, Liao Q. Light-manipulated binary droplet transport on a high-energy surface. LAB ON A CHIP 2023; 23:4287-4301. [PMID: 37682034 DOI: 10.1039/d3lc00582h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/09/2023]
Abstract
Flexible and precise manipulation of droplet transport is of significance for scientific and engineering applications, but real-time and on-demand droplet manipulation remains a challenge. Herein, we report a strategy using light for the outstanding manipulation of binary droplet motion on a high-energy surface and reveal the underlying mechanism. Upon irradiation to a substrate by a focused light beam, the substrate can provide a localized heating source via photothermal conversion, and a binary droplet can be flexibly transported on a high-energy surface with free contact-line pinning, exhibiting light-propelled droplet transport. We theoretically showed that the surface tension gradient across the droplet interface resulting from the localized photothermal effect is responsible for actuating droplet transport. Remarkably, the high reconfigurability and flexibility of light allowed for binary droplet transport with dynamically tunable velocity and direction as well as arbitrary trajectory assisted by 2D channels on a high-energy surface. Complex droplet transportation, controllable droplet coalescence, and anti-gravity motion were realized. The promising applicability of this light-fueled droplet platform was also demonstrated by directional transport of biosample droplets containing DNA molecules and cells, as well as successional microreactions.
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Affiliation(s)
- Wei Li
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Dongliang Li
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Xun Zhu
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Dingding Ye
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Yang Yang
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Hong Wang
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Rong Chen
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
| | - Qiang Liao
- Key Laboratory of Low-grade Energy Utilization Technologies and Systems (Chongqing University), Ministry of Education, Chongqing 400030, China.
- Institute of Engineering Thermophysics, School of Energy and Power Engineering, Chongqing University, Chongqing 400030, China
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Takamatsu Y, Yamato C, Kuwahara M, Saito Y, Saiki T. All-Optical Rapid Formation, Transport, and Sustenance of a Sessile Droplet in a Two-Dimensional Slit with Few-Micrometer Separation. MICROMACHINES 2023; 14:1460. [PMID: 37512771 PMCID: PMC10383034 DOI: 10.3390/mi14071460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/01/2023] [Accepted: 07/15/2023] [Indexed: 07/30/2023]
Abstract
We present a sessile droplet manipulation platform that enables the formation and transport of a droplet on a light-absorbing surface via local laser-beam irradiation. The mechanism relies on solutocapillary Marangoni flow arising from a concentration gradient in a binary mixture liquid. Because the mixture is strongly confined in a two-dimensional slit with a spacing of a few micrometers, the wetting film is stably sustained, enabling the rapid formation, deformation, and transport of a sessile droplet. In addition, to sustain the droplet in the absence of laser irradiation, we developed a method to bridge the droplet between the top and bottom walls of the slit. The bridge is stably sustained because of the hydrophilicity of the slit wall. Splitting and merging of the droplet bridges are also demonstrated.
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Affiliation(s)
- Yuka Takamatsu
- Graduate School of Science and Technology, Keio University, Yokohama 223-8522, Kanagawa, Japan
| | - Chizuru Yamato
- Graduate School of Science and Technology, Keio University, Yokohama 223-8522, Kanagawa, Japan
| | - Masashi Kuwahara
- National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8560, Ibaraki, Japan
| | - Yuta Saito
- National Institute of Advanced Industrial Science and Technology, Tsukuba 305-8560, Ibaraki, Japan
| | - Toshiharu Saiki
- Graduate School of Science and Technology, Keio University, Yokohama 223-8522, Kanagawa, Japan
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Near-infrared-laser-navigated dancing bubble within water via a thermally conductive interface. Nat Commun 2022; 13:5749. [PMID: 36180429 PMCID: PMC9525293 DOI: 10.1038/s41467-022-33424-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 09/16/2022] [Indexed: 11/23/2022] Open
Abstract
Precise manipulation of droplets or bubbles hosts a broad range of applications for microfluidic devices, drug delivery, and soft robotics. Generally the existing approaches via passively designing structured surfaces or actively applying external stimuli, inherently confine their motions within the planar or curved geometry at a slow speed. Consequently the realization of 3D manipulation, such as of the underwater bubbles, remains challenging. Here, during the near-infrared-laser impacting on water, by simply introducing a thermally conductive interface, we unexpectedly observe a spontaneously bouncing bubble with hundreds-of-micrometer diameter at tens-of-Hertz frequency. The unique formation of temperature inversion layer in our system generates the depth-dependent thermal Marangoni force responsible for the bouncing behavior. Both the scaling analysis and numerical simulation agree with observations quantitatively. Furthermore, by controlling the navigation speed of the laser beam, the bubble not only shows excellent steerability with velocity up to 40 mm/s, but also exhibits distinctive behaviors from bouncing to dancing within water. We demonstrate the potential applications by steering the bubble within water to specifically interact with tiny objects, shedding light on the fabrication of bubble-based compositions in materials science and contamination removal in water treatment. Precise manipulation of droplets or bubbles hosts a broad range of applications for microfluidic devices, drug delivery, and soft robotics. Here, Hu et al. show the manipulation of Marangoni-driven dancing bubbles on water using a near-infrared-laser in a frequency of tens-of-Hertz.
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Abstract
The interplay between phase separation and wetting of multicomponent mixtures is ubiquitous in nature and technology and recently gained significant attention across scientific disciplines, due to the discovery of biomolecular condensates. It is well understood that sessile droplets, undergoing phase separation in a static wetting configuration, exhibit microdroplet nucleation at their contact lines, forming an oil ring during later stages. However, very little is known about the dynamic counterpart, when phase separation occurs in a nonequilibrium wetting configuration, i.e., spreading droplets. Here we show that liquid-liquid phase separation strongly couples to the spreading motion of three-phase contact lines. Thus, the classical Cox-Voinov law is not applicable anymore, because phase separation adds an active spreading force beyond the capillary driving. Intriguingly, we observe that spreading starts well before any visible nucleation of microdroplets in the main droplet. Using high-speed ellipsometry, we further demonstrate that the evaporation-induced enrichment, together with surface forces, causes an even earlier nucleation in the wetting precursor film around the droplet, initiating the observed wetting transition. We expect our findings to improve the fundamental understanding of phase separation processes that involve dynamical contact lines and/or surface forces, with implications in a wide range of applications, from oil recovery or inkjet printing to material synthesis and biomolecular condensates.
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Yang Y, Chen R, Zhu X, Ye D, Yang Y, Li W, Li D, Li H, Liao Q. Light-Fueled Submarine-Like Droplet. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2201341. [PMID: 35596606 PMCID: PMC9313504 DOI: 10.1002/advs.202201341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 04/25/2022] [Indexed: 06/15/2023]
Abstract
Flexibly and precisely manipulating 3D droplet transportation is a fundamental challenge for broad implications in diagnostics, drug delivery, bioengineering, etc. Herein, a light method is developed for manipulating a droplet to make it behave like a submarine. This light method enables flexible 3D transportation, stable suspension, and floating of a droplet, which can be freely altered. It is demonstrated that the localized photothermal effect induced thermocapillary flow in the water droplet/oil phase is responsible for energizing and manipulating the droplet. With such remarkable motility, the light-fueled submarine-like droplet successfully realizes various functions such as the acid-base detection, particle capture and transportation, and target crystal collection, dissolution and transportation. It is demonstrated that the light-fueled submarine-like droplet shows promising perspective for long-sought precise droplet manipulation in various applications.
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Affiliation(s)
- Yijing Yang
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Rong Chen
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Xun Zhu
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Dingding Ye
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Yang Yang
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Wei Li
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Dongliang Li
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Haonan Li
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
| | - Qiang Liao
- Key Laboratory of Low‐Grade Energy Utilization Technologies and Systems (Chongqing University)Ministry of EducationChongqing400030China
- Institute of Engineering ThermophysicsSchool of Energy and Power EngineeringChongqing UniversityChongqing400030China
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Liu C, Liu X, Tang Q, Zhou W, Ma Y, Gong Z, Chen J, Zheng H, Joo SW. Three-Dimensional Droplet Manipulation with Electrostatic Levitation. Anal Chem 2022; 94:8217-8225. [PMID: 35622947 DOI: 10.1021/acs.analchem.2c00178] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An active and precise method for three-dimensional (3D) droplet manipulation is introduced. By modulating the local electrostatic force acting on droplets in carrier oil between needle plate electrodes, the vertical motion of droplets can be controlled, including the droplet levitation at the interface between the carrier oil and the air. Levitated droplets can be translated horizontally with high efficiency by the motion of the needle electrode. With controllable local deformation on the flexible plate electrode, selective manipulation can be realized for multiple droplets. Applying the manipulation method proposed, a platform is built and various droplet handling, such as transport, merging, and mixing, is performed effectively. Complex droplet transport trajectories are achieved by moving the needle electrode. The droplet transport velocity can reach up to 37 mm/s. The introduced method has fundamental advantages of avoiding cross-contamination between droplets, enhancing the flexibility, eliminating the transport track constraint, and lowering costs with straightforward and precise droplet manipulation.
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Affiliation(s)
- Chang Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Xiaofeng Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Qiang Tang
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Wenhao Zhou
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Yan Ma
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Zheng Gong
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Junhao Chen
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Huai Zheng
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China.,The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Sang Woo Joo
- School of Mechanical Engineering, Yeungnam University, Gyeongsan 38541, South Korea
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Ryu J, Ko HS, Kim H. Vapor Absorption and Marangoni Flows in Evaporating Drops. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:2185-2191. [PMID: 35148120 DOI: 10.1021/acs.langmuir.1c01765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
We experimentally and analytically studied vapor-driven solutal Marangoni flow by varying volatile liquid sources on top of the water droplet. We checked and compared the effects of solubility and vapor pressures of volatile liquids on the internal flow pattern using particle image velocimetry (PIV) and the droplet shape using shadowgraphy experiments. To explain the internal flow, we explored the absorption and evaporation mechanism of the vapors and we found that Henry's constant of the volatile liquid is the primary factor. Based on the scaling arguments, we developed theoretical models to explain how much vapor is absorbed into the water droplet, and how the flow pattern occurs and evolves. The scaling models show that there is a good agreement with the experimental results. We believe that understanding this phenomenon is useful for microfluidics applications and fundamental liquid-gas interface problems where vapors can be absorbed into another liquid.
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Affiliation(s)
- Junil Ryu
- Department of Mechanical Engineering, KAIST, Daejeon 34141, South Korea
| | - Han Seo Ko
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, South Korea
| | - Hyoungsoo Kim
- Department of Mechanical Engineering, KAIST, Daejeon 34141, South Korea
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Tang Q, Liu X, Cui X, Su Z, Zheng H, Tang J, Joo SW. Contactless Discharge-Driven Droplet Motion on a Nonslippery Polymer Surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:14697-14702. [PMID: 34894688 DOI: 10.1021/acs.langmuir.1c02462] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Droplet manipulation is the cornerstone of many modern technologies. It is still challenging to drive the droplet motion on nonslippery surfaces flexibly. We present a droplet manipulation method on nonslippery polymer surfaces based on the corona discharge. With the corona discharge of two-needle electrodes with opposite polarities, the droplet's charge polarity can be switched, which results in the directionally droplet transport on a charged polymer surface with the oscillation. Here, such droplet behaviors are presented in detail. Dependence of the motion on the critical distance and driving distance between the droplet and the needle electrode is revealed. The driving mechanism is verified by experiments and simulations. This work enriches the droplet manipulation techniques on nonslippery surfaces for various applications, such as combinatory chemistry, biochemical, and medical detection.
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Affiliation(s)
- Qiang Tang
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Xiaofeng Liu
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Xiaxia Cui
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Zhenpeng Su
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Huai Zheng
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
- School of Power and Mechanical Engineering, Wuhan University, Wuhan 430072, China
| | - Jau Tang
- The Institute of Technological Sciences, Wuhan University, Wuhan 430072, China
| | - Sang Woo Joo
- School of Mechanical Engineering, Yeungnam University, Gyeongsan 38541, South Korea
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