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Cardin K, Cabrera-Booman F, Cal RB. Droplet jump from a particle bed. SOFT MATTER 2024; 20:2887-2891. [PMID: 38421305 DOI: 10.1039/d3sm01501g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
Drop tower experiments have been performed to study droplet jump from a particle bed across a wide range of fluid viscosities. Here the droplet jumps from the particle bed in response to the apparent step reduction from terrestrial gravity to microgravity when the experiment is dropped and enters free fall. The presence of a particle layer has been found to affect contact line dissipation and the overall jumping behavior of droplets. Additionally, the study has identified the impact of the Ohnesorge number (Oh) on droplet morphology. The investigation has yielded results that not only validate a modified version of the spring-mass-damper model for droplet rebound [Jha et al., Soft Matter, 2020, 16, 7270] but also extend its applicability to previously unexplored initial conditions. In particular, the model predicts droplet jump time and velocity. Moreover, the presence of particle layers has been found to effectively eliminate contact line dissipation without introducing substantial additional forms of dissipation. Experiments have been conducted at the Dryden Drop Tower facility at Portland State University. Particle beds have been constructed using polyethylene and polystyrene poly-dispersed spheres with diameters ranging from 125-150 μm and 600-1000 μm, respectively. The beds have been created by depositing a thin layer of particles on a glass substrate. The experimental conditions have allowed the exploration of a large parameter space of Bo0 1.8-8.6, We 0.05-1.40, and Oh 0.001-1.900.
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Affiliation(s)
- Karl Cardin
- Department of Mechanical & Materials Engineering, Portland State University, Portland, OR 97201, USA.
| | - Facundo Cabrera-Booman
- Department of Mechanical & Materials Engineering, Portland State University, Portland, OR 97201, USA.
| | - Raúl Bayoán Cal
- Department of Mechanical & Materials Engineering, Portland State University, Portland, OR 97201, USA.
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Sneha Ravi A, Dalvi S. Liquid Marbles and Drops on Superhydrophobic Surfaces: Interfacial Aspects and Dynamics of Formation: A Review. ACS OMEGA 2024; 9:12307-12330. [PMID: 38524492 PMCID: PMC10956110 DOI: 10.1021/acsomega.3c07657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 02/12/2024] [Accepted: 02/14/2024] [Indexed: 03/26/2024]
Abstract
Liquid marbles (LMs) are droplets encapsulated with powders presenting varied roughness and wettability. These LMs have garnered a lot of attention due to their dual properties of leakage-free and quick transport on both solid and liquid surfaces. These droplets are in a Cassie-Baxter wetting state sitting on both roughness and air pockets existing between particles. They are also reminiscent of the state of a drop on a superhydrophobic (SH) surface. In this review, LMs and bare droplets on SH surfaces are comparatively investigated in terms of two aspects: interfacial and dynamical. LMs present a fascinating class of soft matter due to their superior interfacial activity and their remarkable stability. Inherently hydrophobic powders form stable LMs by simple rolling; however, particles with defined morphologies and chemistries contribute to the varied stability of LMs. The factors contributing to this interesting robustness with respect to bare droplets are then identified by tests of stability such as evaporation and compression. Next, the dynamics of the impact of a drop on a hydrophobic powder bed to form LMs is studied vis-à̀-vis that of drop impact on flat surfaces. The knowledge from drop impact phenomena on flat surfaces is used to build and complement insights to that of drop impact on powder surfaces. The maximum spread of the drop is empirically understood in terms of dimensionless numbers, and their drawbacks are highlighted. Various stages of drop impact-spreading, retraction and rebound, splashing, and final outcome-are systematically explored on both solid and hard surfaces. The implications of crater formation and energy dissipations are discussed in the case of granular beds. While the drop impact on solid surfaces is extensively reviewed, deep interpretation of the drop impact on granular surfaces needs to be improved. Additionally, the applications of each step in the sequence of drop impact phenomena on both substrates are also identified. Next, the criterion for the formation of peculiar jammed LMs was examined. Finally, the challenges and possible future perspectives are envisaged.
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Affiliation(s)
- Apoorva Sneha Ravi
- Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382055, Gujarat, India
| | - Sameer Dalvi
- Chemical Engineering, Indian Institute of Technology Gandhinagar, Palaj, Gandhinagar 382055, Gujarat, India
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3
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Lathia R, Dey Modak C, Sen P. Suppression of droplet pinch-off by early onset of interfacial instability. J Colloid Interface Sci 2023; 646:606-615. [PMID: 37210908 DOI: 10.1016/j.jcis.2023.05.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 05/05/2023] [Accepted: 05/10/2023] [Indexed: 05/23/2023]
Abstract
HYPOTHESIS Interfacial instabilities cause undesirable droplet breakage during impact. Such breakage affects many applications, such as printing, spraying, etc. Particle coating over a droplet can significantly change the impact process and stabilize it against breakage. This work investigates the impact dynamics of particle-coated droplets, which mostly remains unexplored. EXPERIMENTS Particle-coated droplets of different mass loading were formed using volume addition. The prepared droplets were impacted on superhydrophobic surfaces, and their dynamics were recorded using a high-speed camera. FINDINGS We report an intriguing phenomenon where an interfacial fingering instability helps suppress pinch-off in particle-coated droplets. This island of breakage suppression, where the droplet maintains its intactness upon impact, appears in a regime of Weber numbers where bare droplet breakage is inevitable. The onset of fingering instability in particle-coated droplets is observed at much lower impact energy, around two times less than the bare droplet. The instability is characterized and explained using the rim Bond number. The instability suppresses pinch-off because of the higher losses associated with the formation of stable fingers. Such instability can also be seen in dust/pollen-covered surfaces, making it useful in many applications related to cooling, self-cleaning, anti-icing etc.
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Affiliation(s)
- Rutvik Lathia
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Chandantaru Dey Modak
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India
| | - Prosenjit Sen
- Centre for Nano Science and Engineering, Indian Institute of Science, Bangalore 560012, India.
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Mazur R, Ryżak M, Sochan A, Beczek M, Polakowski C, Bieganowski A. Soil Deformation after Water Drop Impact-A Review of the Measurement Methods. SENSORS (BASEL, SWITZERLAND) 2022; 23:121. [PMID: 36616719 PMCID: PMC9823695 DOI: 10.3390/s23010121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
Water erosion is an unfavorable phenomenon causing soil degradation. One of the factors causing water erosion is heavy or prolonged rainfall, the first effect of which is the deformation of the soil surface and the formation of microcraters. This paper presents an overview of research methods allowing the study of microcraters as well as the process of their formation. A tabular summary of work on the measurements of various quantities describing the craters is presented. The said quantities are divided into three groups: (i) static quantities, (ii) dynamic quantities, and (iii) dimensionless parameters. The most important measurement methods used to study crater properties, such as (i) basic manual measurement methods, (ii) photography, (iii) high-speed imaging, (iv) profilometers, (v) 3D surface modelling, and (vi) computed tomography (CT) and its possibilities and limitations are discussed. The main challenges and prospects of research on soil surface deformation are also presented.
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Affiliation(s)
| | - Magdalena Ryżak
- Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
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5
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Operating limits and parametric sensitivity of laboratory device for continuous production of liquid marbles. POWDER TECHNOL 2022. [DOI: 10.1016/j.powtec.2022.117944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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6
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Lekshmi BS, Varanakkottu SN. Droplet-Impact Driven Formation of Ultralow Volume Liquid Marbles with Enhanced Mechanical Stability and Sensing Ability. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:11743-11752. [PMID: 36109337 DOI: 10.1021/acs.langmuir.2c01880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Liquid marbles (LMs), droplets encapsulated with micro/nanoparticles, have attracted significant attention owing to their potential applications in various fields, ranging from microbioreactors to sensors. The volume of the LMs is a key parameter determining their mechanical stability and gas sensing ability. It is ideal to work with small volumes because of their better mechanical stability and gas sensing power compared to the larger LMs. Though many methods exist for producing LMs in the volume range above 2 μL, no reliable method exists to prepare fully coated submicroliter LMs with tunable volume. The situation becomes even more difficult when one attempts to produce tiny Janus Liquid Marbles (JLMs). This paper presents a simple, single-step, and efficient strategy for obtaining both the pristine LMs and JLMs in the volume range 200 nL to 18 μL. The core idea relies on the impact of a liquid drop on a particle bed at a Weber number of ∼55 to produce two daughter droplets and to convert these droplets into LMs/JLMs. The whole process takes only a few tens of milliseconds (∼50 ms). We have rendered the experimental schemes so that both the JLMs and pristine LMs can be produced in a single step, with control over their volume. The mechanical stability analysis of the prepared marbles indicates that 200 nL is 5 times more stable than 10 μL of LMs. The 0.72 μL LMs prepared with a 0.5 v/v % phenolphthalein indicator solution showed 3 times faster response time to ammonia gas sensing than 10 μL of LMs. The results presented in this work open up a new route for the rapid and reliable production of both multilayered LMs and JLMs with tunable volume in a wide range (200 nL to 18 μL).
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Affiliation(s)
- Bindhu Sunilkumar Lekshmi
- Optofluidics and Interface Science Laboratory, Department of Physics, National Institute of Technology Calicut, Kozhikode, Kerala India, 673601
| | - Subramanyan Namboodiri Varanakkottu
- Optofluidics and Interface Science Laboratory, Department of Physics, National Institute of Technology Calicut, Kozhikode, Kerala India, 673601
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Zhang Y, Cui H, Binks BP, Shum HC. Liquid Marbles under Electric Fields: New Capabilities for Non-wetting Droplet Manipulation and Beyond. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:9721-9740. [PMID: 35918302 DOI: 10.1021/acs.langmuir.2c01127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The study of liquid marbles (LMs) composed of stabilizing liquid droplets with solid particles in a gaseous environment has matured into an established area in surface and colloid science. The minimized "solid-liquid-air" triphase interface enables LMs to drastically reduce adhesion to a solid substrate, making them unique non-wetting droplets transportable with limited energy. The small volume, enclosed environment, and simple preparation render them suitable microreactors in industrial applications and processes such as cell culture, material synthesis, and blood coagulation. Extensive application contexts request precise and highly efficient manipulations of these non-wetting droplets. Many external fields, including magnetic, acoustic, photothermal, and pH, have emerged to prepare, deform, actuate, coalesce, mix, and disrupt these non-wetting droplets. Electric fields are rising among these external stimuli as an efficient source for manipulating the LMs with high controllability and a significant ability to contribute further to proposed applications. This Feature Article attempts to outline the recent developments related to LMs with the aid of electric fields. The effects of electric fields on the preparation and manipulation of LMs with intricate interfacial processes are discussed in detail. We highlight a wealth of novel electric field-involved LM-based applications and beyond while also envisaging the challenges, opportunities, and new directions for future development in this emerging research area.
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Affiliation(s)
- Yage Zhang
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam 999077, Hong Kong, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin 999077, Hong Kong, China
| | - Huanqing Cui
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam 999077, Hong Kong, China
| | - Bernard P Binks
- Department of Chemistry, University of Hull, Hull HU6 7RX, United Kingdom
| | - Ho Cheung Shum
- Department of Mechanical Engineering, The University of Hong Kong, Pokfulam 999077, Hong Kong, China
- Advanced Biomedical Instrumentation Centre, Hong Kong Science Park, Shatin 999077, Hong Kong, China
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Sun Y, Zheng Y, Liu C, Zhang Y, Wen S, Song L, Zhao M. Liquid marbles, floating droplets: preparations, properties, operations and applications. RSC Adv 2022; 12:15296-15315. [PMID: 35693225 PMCID: PMC9118372 DOI: 10.1039/d2ra00735e] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 04/21/2022] [Indexed: 12/20/2022] Open
Abstract
Liquid marbles (LMs) are non-wettable droplets formed with a coating of hydrophobic particles. They can move easily across either solid or liquid surfaces since the hydrophobic particles protect the internal liquid from contacting the substrate. In recent years, mainly due to their simple preparation, abundant materials, non-wetting/non-adhesive properties, elasticities and stabilities, LMs have been applied in many fields such as microfluidics, sensors and biological incubators. In this review, the recent advances in the preparation, physical properties and applications of liquid marbles, especially operations and floating abilities, are summarized. Moreover, the challenges to achieve uniformity, slow volatilization and stronger stability are pointed out. Various applications generated by LMs’ structural characteristics are also expected. The recent advances in the preparation, physical properties and applications of liquid marbles, especially operations and floating abilities, are summarized.![]()
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Affiliation(s)
- Yukai Sun
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
| | - Yelong Zheng
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
| | - Chuntian Liu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
| | - Yihan Zhang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
| | - Shiying Wen
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
| | - Le Song
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
| | - Meirong Zhao
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University Tianjin China
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Dedovets D, Li Q, Leclercq L, Nardello‐Rataj V, Leng J, Zhao S, Pera‐Titus M. Multiphase Microreactors Based on Liquid–Liquid and Gas–Liquid Dispersions Stabilized by Colloidal Catalytic Particles. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202107537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Dmytro Dedovets
- Eco-Efficient Products and Processes Laboratory (E2P2L) UMI 3464 CNRS-Solvay 3966 Jin Du Road, Xin Zhuang Ind Zone 201108 Shanghai China
- Laboratoire du Futur (LOF) UMR 5258, CNRS-Solvay-Universite Bordeaux 1 178 Av Dr Albert Schweitzer 33608 Pessac Cedex France
| | - Qingyuan Li
- Eco-Efficient Products and Processes Laboratory (E2P2L) UMI 3464 CNRS-Solvay 3966 Jin Du Road, Xin Zhuang Ind Zone 201108 Shanghai China
| | - Loïc Leclercq
- Univ Lille CNRS Centrale Lille Univ Artois UMR 8181 UCCS F-59000 Lille France
| | | | - Jacques Leng
- Laboratoire du Futur (LOF) UMR 5258, CNRS-Solvay-Universite Bordeaux 1 178 Av Dr Albert Schweitzer 33608 Pessac Cedex France
| | - Shuangliang Zhao
- Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology School of Chemistry and Chemical Engineering Guangxi University 530004 Nanning China
| | - Marc Pera‐Titus
- Eco-Efficient Products and Processes Laboratory (E2P2L) UMI 3464 CNRS-Solvay 3966 Jin Du Road, Xin Zhuang Ind Zone 201108 Shanghai China
- Cardiff Catalysis Institute School of Chemistry Cardiff University Main Building, Park Place Cardiff CF10 3AT UK
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10
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Dedovets D, Li Q, Leclercq L, Nardello-Rataj V, Leng J, Zhao S, Pera-Titus M. Multiphase Microreactors Based on Liquid-Liquid and Gas-Liquid Dispersions Stabilized by Colloidal Catalytic Particles. Angew Chem Int Ed Engl 2021; 61:e202107537. [PMID: 34528366 PMCID: PMC9293096 DOI: 10.1002/anie.202107537] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Indexed: 01/08/2023]
Abstract
Pickering emulsions, foams, bubbles, and marbles are dispersions of two immiscible liquids or of a liquid and a gas stabilized by surface‐active colloidal particles. These systems can be used for engineering liquid–liquid–solid and gas–liquid–solid microreactors for multiphase reactions. They constitute original platforms for reengineering multiphase reactors towards a higher degree of sustainability. This Review provides a systematic overview on the recent progress of liquid–liquid and gas–liquid dispersions stabilized by solid particles as microreactors for engineering eco‐efficient reactions, with emphasis on biobased reagents. Physicochemical driving parameters, challenges, and strategies to (de)stabilize dispersions for product recovery/catalyst recycling are discussed. Advanced concepts such as cascade and continuous flow reactions, compartmentalization of incompatible reagents, and multiscale computational methods for accelerating particle discovery are also addressed.
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Affiliation(s)
- Dmytro Dedovets
- Eco-Efficient Products and Processes Laboratory (E2P2L), UMI 3464 CNRS-Solvay, 3966 Jin Du Road, Xin Zhuang Ind Zone, 201108, Shanghai, China.,Laboratoire du Futur (LOF), UMR 5258, CNRS-Solvay-Universite Bordeaux 1, 178 Av Dr Albert Schweitzer, 33608, Pessac Cedex, France
| | - Qingyuan Li
- Eco-Efficient Products and Processes Laboratory (E2P2L), UMI 3464 CNRS-Solvay, 3966 Jin Du Road, Xin Zhuang Ind Zone, 201108, Shanghai, China
| | - Loïc Leclercq
- Univ Lille, CNRS, Centrale Lille, Univ Artois, UMR 8181 UCCS, F-59000, Lille, France
| | | | - Jacques Leng
- Laboratoire du Futur (LOF), UMR 5258, CNRS-Solvay-Universite Bordeaux 1, 178 Av Dr Albert Schweitzer, 33608, Pessac Cedex, France
| | - Shuangliang Zhao
- Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology, School of Chemistry and Chemical Engineering, Guangxi University, 530004, Nanning, China
| | - Marc Pera-Titus
- Eco-Efficient Products and Processes Laboratory (E2P2L), UMI 3464 CNRS-Solvay, 3966 Jin Du Road, Xin Zhuang Ind Zone, 201108, Shanghai, China.,Cardiff Catalysis Institute, School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff, CF10 3AT, UK
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11
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Lekshmi BS, Yadav AS, Ranganathan P, Varanakkottu SN. Simple and Continuous Fabrication of Janus Liquid Marbles with Tunable Particle Coverage Based on Controlled Droplet Impact. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15396-15402. [PMID: 33306396 DOI: 10.1021/acs.langmuir.0c02988] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Liquid marbles are gaining increased attention because of their added advantages such as low evaporation rates, less friction, and ease of manipulation over the pristine liquid drop. Their functionalities could be further enhanced by incorporating different types of particles (size, hydrophobicity, chemical properties, etc.), commonly called Janus liquid marbles (JLMs). However, their fabrication process remains a challenge, especially when we require continuous production. Here, we present a simple and fast approach for the fabrication of JLMs covered with nano- and microparticles in an additive-free environment based on the controlled impact of a water drop over the particle beds. The fabrication process involves collection of polyvinylidene difluoride particles (PVDF, particle type 1) by a water drop followed by its impact over an uncompressed bed of black toner particles (BTP, particle type 2). The whole process takes a time of approximately 30 ms only. The drop impact and the condition of the JLM formation were explained based on the Weber number (We) and maximum spread (βm) analysis. A theoretical model based on the energy balance analysis is performed to calculate the maximum spreading (βm), and the experimental and theoretical analyses are found to be in good agreement. Tunability in particle coverage is demonstrated by varying the droplet volume in the range of 5-15 μL. We further extend this strategy for the fast and continuous production of nearly identical JLMs, which could enhance the capabilities of open-surface microfluidic applications.
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Affiliation(s)
- Bindhu Sunilkumar Lekshmi
- Optofluidics and Interface Science Laboratory, Department of Physics, National Institute of Technology Calicut, Kozhikode 673601, India
| | - Ajeet Singh Yadav
- Optofluidics and Interface Science Laboratory, Department of Physics, National Institute of Technology Calicut, Kozhikode 673601, India
| | - Panneerselvam Ranganathan
- Department of Chemical Engineering, National Institute of Technology Calicut, Kozhikode 673601, India
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13
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Mozhi Devan Padmanathan A, Sneha Ravi A, Choudhary H, Varanakkottu SN, Dalvi SV. Predictive Framework for the Spreading of Liquid Drops and the Formation of Liquid Marbles on Hydrophobic Particle Bed. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:6657-6668. [PMID: 31039316 DOI: 10.1021/acs.langmuir.9b00698] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In this work, we have developed a model to describe the behavior of liquid drops upon impaction on hydrophobic particle bed and verified it experimentally. Poly(tetrafluoroethylene) (PTFE) particles were used to coat drops of water, aqueous solutions of glycerol (20, 40, and 60% v/v), and ethanol (5 and 12% v/v). The experiments were conducted for Weber number ( We) ranging from 8 to 130 and Reynolds number ( Re) ranging from 370 to 4460. The bed porosity was varied from 0.8 to 0.6. The experimental values of βmax (ratio of the diameter at the maximum spreading condition to the initial drop diameter) were estimated from the time-lapsed images captured using a high-speed camera. The theoretical βmax was estimated by making energy balances on the liquid drop. The proposed model accounts for the energy losses due to viscous dissipation and crater formation along with a change in kinetic energy and surface energy. A good agreement was obtained between the experimental βmax and the estimated theoretical βmax. The proposed model yielded a least % absolute average relative deviation (% AARD) of 5.5 ± 4.3 compared to other models available in the literature. Further, it was found that the liquid drops impacting on particle bed are completely coated with PTFE particles with βmax values greater than 2.
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Affiliation(s)
| | - Apoorva Sneha Ravi
- Chemical Engineering , Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355 , Gujarat , India
| | - Hema Choudhary
- Chemical Engineering , Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355 , Gujarat , India
| | | | - Sameer V Dalvi
- Chemical Engineering , Indian Institute of Technology Gandhinagar , Palaj, Gandhinagar 382355 , Gujarat , India
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Gao T, Singaravelu ASS, Oka S, Ramachandran R, Štepánek F, Chawla N, Emady HN. Granule formation and structure from single drop impact on heterogeneous powder beds. Int J Pharm 2018; 552:56-66. [DOI: 10.1016/j.ijpharm.2018.09.036] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 09/11/2018] [Accepted: 09/17/2018] [Indexed: 11/15/2022]
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Li C, Simmons JA, Moradiafrapoli M, Marston JO. Direct visualization of particle attachment to a pendant drop. SOFT MATTER 2017; 13:1444-1454. [PMID: 28124711 DOI: 10.1039/c6sm02495e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An experimental investigation is carried out into the attachment of a single particle to a liquid drop. High-speed videography is used to directly visualize the so-called 'snap-in' effect which occurs rapidly over sub-millisecond timescales. Using high-magnification, the evolution of the contact line around the particle is tracked and dynamic features such as the contact angle, wetted radius and force are extracted from these images to help build a fundamental understanding of the process. By examining the wetted length in terms of an arc angle, ϕ, it is shown that the early wetting stage is an inertial-dominated process and best described by a power law relation, i.e. ϕ ∼ (t/τ)α, where τ is an inertial timescale. For the subsequent lift-off stage, the initial particle displacement is matched with that predicted using a simple balance between particle weight and capillary force with reasonable agreement. The lift-off force is shown to be on the order of 1-100 μN, whilst the force of impacting droplets is known to be on the order of 10-1000 mN. This explains the ease in which liquid marbles are formed during impact experiments.
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Affiliation(s)
- C Li
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
| | - J A Simmons
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
| | - M Moradiafrapoli
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
| | - J O Marston
- Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA.
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Supakar T, Kumar A, Marston JO. Impact dynamics of particle-coated droplets. Phys Rev E 2017; 95:013106. [PMID: 28208334 DOI: 10.1103/physreve.95.013106] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Indexed: 06/06/2023]
Abstract
We present findings from an experimental study of the impact of liquid marbles onto solid surfaces. Using dual-view high-speed imaging, we reveal details of the impact dynamics previously not reported. During the spreading stage it is observed that particles at the surface flow rapidly to the periphery of the drop, i.e., the lamella. We characterize the spreading with the maximum spread diameter, comparing to impacts of pure liquid droplets. The principal result is a power-law scaling for the normalized maximum spread in terms of the impact Weber number, D_{max}/D_{0}∼We^{α}, with α≈1/3. However, the best description of the spreading is obtained by considering a total energy balance, in a similar fashion to Pasandideh-Fard et al. [Phys. Fluids 8, 650 (1996)]PHFLE61070-663110.1063/1.868850. By using hydrophilic target surfaces, the marble integrity is lost even for moderate impact speeds as the particles at the surface separate and allow liquid-solid contact to occur. Remarkably, however, we observe no significant difference in the maximum spread between hydrophobic and hydrophilic targets, which is rationalized by the presence of the particles. Finally, for the finest particles used, we observe the formation of nonspherical arrested shapes after retraction and rebound from hydrophobic surfaces, which is quantified by a circularity measurement of the side profiles.
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Affiliation(s)
- T Supakar
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, USA
| | - A Kumar
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, USA
| | - J O Marston
- Department of Chemical Engineering, Texas Tech University, Lubbock, Texas 79409, USA
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