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Li Z, Liu B, Guo Y, Bi L, Hu H, Zeng T, Li R, Theodorakis PE. Evaporation Dynamics of Macro- and Nanodroplets on Heated Hydrophilic Rough Substrates: The Effect of Roughness and Scale. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024. [PMID: 38321753 DOI: 10.1021/acs.langmuir.3c03147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Droplet evaporation on rough substrates plays an essential role in cooling and micro/nanoparticle assembly. Currently, there are numerous macroscopic experiments and theoretical models to investigate the droplet evaporation behavior on rough substrates. However, due to the complexity of this phenomenon, understanding its mechanisms solely through macroscale studies is difficult. To this end, molecular dynamics simulations of the models with distinct roughness factors are performed, and the obtained results are compared with those of relevant experiments of droplet evaporation on three hydrophilic substrates with different roughness average of 0.1, 0.15, and 0.2 μm, respectively. In this way, we assess the evaporation on these rough systems and the effect of scale on macro- and nanodroplets, which allows us to explore deeper the mechanism of droplet evaporation on rough hydrophilic substrates. In particular, we find that in the case of macroscale droplets, the evaporation mode remains the same with increasing roughness, pointing to a combined mixed and constant-contact-radius (CCR) mode. In the case of nanoscale droplets, the evaporation model is the constant-contact-angle mode when the roughness factor r = 1, while the mixed and CCR modes are found for r = 1.5 and 2, respectively. The scale effect has significant influence on the evaporation pattern of droplets on rough hydrophilic substrates. Moreover, it is also found that increasing the roughness of substrates expands the substrate-droplet contact area on both the macro- and nanoscale, which in turn enhances the heat transfer from the substrate toward the droplet. We anticipate that this first systematic analysis of scale effects provides further insights into the evaporation dynamics of droplets on rough hydrophilic substrates and has significant implications for the advancement of nanotechnology.
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Affiliation(s)
- Zhuorui Li
- Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China
| | - Bin Liu
- Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China
- International Centre in Fundamental and Engineering Thermophysics, Tianjin University of Commerce, Tianjin 300134, China
- Key Lab of Agricultural Products Low Carbon Cold Chain of Ministry of Agriculture and Rural Affairs, Tianjin University of Commerce, Tianjin 300134, China
| | - Yali Guo
- Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education, Dalian University of Technology, Dalian 116024, China
| | - Lisen Bi
- Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China
| | - Hengxiang Hu
- Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China
| | - Tao Zeng
- Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China
| | - Rui Li
- Tianjin Key Laboratory of Refrigeration Technology, Tianjin University of Commerce, Tianjin 300134, China
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Hou H, Wu X, Hu Z, Gao S, Yuan Z. Coalescence-Induced Droplet Jumping on Superhydrophobic Surfaces with Annular Wedge-Shaped Micropillar Arrays. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:18825-18833. [PMID: 38096374 DOI: 10.1021/acs.langmuir.3c02534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
The coalescence-induced droplet jumping on superhydrophobic surfaces has extensive application potential in water harvesting, thermal management of electronic devices, and microfluidics. The rational design of the surface structure can influence the interaction between the droplet and the surface, thereby controlling the velocity and direction of the droplet's jumping. In this study, we fabricate the superhydrophobic surface with annular wedge-shaped micropillar arrays, examine the dynamic behavior of condensate droplets on the surface, and measure the temporal and spatial variations of droplet density, average radius, and surface coverage with wedge-shaped micropillars of varying sizes. In addition, the energy analysis of the coalescence-induced droplet jumping reveals that the two primary factors influencing the jumping are the relative size and position of the droplets and micropillars. Further numerical simulations find that the wedge-shaped micropillars cause an asymmetric distribution of pressure within the droplet and at the solid-liquid contact surface, which generates an unbalanced force driving the droplet in the gradient direction of the wedge-shaped micropillar, causing the droplet to jump off the surface with both vertical and gradient-direction velocities. The capacity of the wedge-shaped micropillar surface to transport droplets in the gradient direction increases and then decreases as the relative size of the droplets and micropillars increases. The relative position of the droplet center-of-mass line perpendicular to the bottom edge of the wedge micropillars' trapezoidal shape is more favorable for droplet transport. This work reveals the influence mechanism of surface structure on the velocity and direction of droplet jumping, and the results can guide the microstructure design of superhydrophobic surfaces, which has significant implications for the application of droplet jumping.
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Affiliation(s)
- Huimin Hou
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Xiaomin Wu
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Zhifeng Hu
- Research Center of Solar Power and Refrigeration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Sihang Gao
- Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Energy and Power Engineering, Tsinghua University, Beijing 100084, China
| | - Zhiping Yuan
- Department of Energy and Power Engineering, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
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Sinha Mahapatra P, Ganguly R, Ghosh A, Chatterjee S, Lowrey S, Sommers AD, Megaridis CM. Patterning Wettability for Open-Surface Fluidic Manipulation: Fundamentals and Applications. Chem Rev 2022; 122:16752-16801. [PMID: 36195098 DOI: 10.1021/acs.chemrev.2c00045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Effective manipulation of liquids on open surfaces without external energy input is indispensable for the advancement of point-of-care diagnostic devices. Open-surface microfluidics has the potential to benefit health care, especially in the developing world. This review highlights the prospects for harnessing capillary forces on surface-microfluidic platforms, chiefly by inducing smooth gradients or sharp steps of wettability on substrates, to elicit passive liquid transport and higher-order fluidic manipulations without off-the-chip energy sources. A broad spectrum of the recent progress in the emerging field of passive surface microfluidics is highlighted, and its promise for developing facile, low-cost, easy-to-operate microfluidic devices is discussed in light of recent applications, not only in the domain of biomedical microfluidics but also in the general areas of energy and water conservation.
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Affiliation(s)
- Pallab Sinha Mahapatra
- Micro Nano Bio-Fluidics group, Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai600036, India
| | - Ranjan Ganguly
- Department of Power Engineering, Jadavpur University, Kolkata700098, India
| | - Aritra Ghosh
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois60607, United States
| | - Souvick Chatterjee
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois60607, United States
| | - Sam Lowrey
- Department of Physics, University of Otago, Dunedin9016, New Zealand
| | - Andrew D Sommers
- Department of Mechanical and Manufacturing Engineering, Miami University, Oxford, Ohio45056, United States
| | - Constantine M Megaridis
- Department of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois60607, United States
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Gulfam R, Chen Y. Recent Growth of Wettability Gradient Surfaces: A Review. Research (Wash D C) 2022; 2022:9873075. [PMID: 35935132 PMCID: PMC9327586 DOI: 10.34133/2022/9873075] [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: 03/06/2022] [Accepted: 06/01/2022] [Indexed: 11/06/2022] Open
Abstract
This review reports the recent progress and future prospects of wettability gradient surfaces (WGSs), particularly focusing on the governing principles, fabrication methods, classification, characterization, and applications. While transforming the inherent wettability into artificial wettability via bioinspiration, topographic micro/nanostructures are produced with changed surface energy, resulting in new droplet wetting regimes and droplet dynamic regimes. WGSs have been mainly classified in dry and wet surfaces, depending on the apparent surface states. Wettability gradient has long been documented as a surface phenomenon inducing the droplet mobility in the direction of decreasing wettability. However, it is herein critically emphasized that the wettability gradient does not always result in droplet mobility. Indeed, the sticky and slippery dynamic regimes exist in WGSs, prohibiting or allowing the droplet mobility, respectively. Lastly, the stringent bottlenecks encountered by WGSs are highlighted along with solution-oriented recommendations, and furthermore, phase change materials are strongly anticipated as a new class in WGSs. In all, WGSs intend to open up new technological insights for applications, encompassing water harvesting, droplet and bubble manipulation, controllable microfluidic systems, and condensation heat transfer, among others.
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Affiliation(s)
- Raza Gulfam
- Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
- Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu 210096, China
| | - Yongping Chen
- Jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application, School of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China
- Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu 210096, China
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Al Balushi KM, Sefiane K, Orejon D. Binary mixture droplet wetting on micro-structure decorated surfaces. J Colloid Interface Sci 2022; 612:792-805. [PMID: 35065463 DOI: 10.1016/j.jcis.2021.12.171] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/17/2021] [Accepted: 12/26/2021] [Indexed: 10/19/2022]
Abstract
Liquid surface tension as well as solid structure play a paramount role on the intimate wetting and non-wetting regimes and interactions between liquids droplets and solid substrates. We hypothesise that the coupling of these two variables, independently addressed in the past, eventually offer a wider range of understanding to the surface science and interfacial communities. In this work, intrinsically hydrophobic micro-pillared surfaces varying in the spacing between structures, and pure ethanol, pure water and their binary mixtures (as well as acetone-water and ethylene glycol-water mixtures) are utilised, accessing a wide range of substrate solid fractions and liquid surface tensions experimentally. Wettability measurements are carried out at different azimuthal directions to exemplify the wetting/non-wetting behaviour as well as the droplet asymmetry function of both liquid composition and structure spacing. Our findings reveal that high water concentration droplets, i.e., high surface tension fluids, sit in the Cassie-Baxter regime while partial non-wetting Wenzel or mixed-mode regimes with enhanced droplet asymmetry ensuing for medium and high ethanol concentrations, i.e., low surface tension fluids, below certain micropillar spacing. Beyond micropillar spacing s ≥ 40 µm, the impact of the surface structure on the droplet shape is negligible, and droplets adopt a similar contact angle and circular shape as on a flat smooth hydrophobic surface. Wetting and non-wetting regimes are then supported by classical wetting theories and equations. A wetting regime map for a wide range of surface tension fluids and/or their mixtures on a wide domain of solid fractions is then proposed.
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Affiliation(s)
- Khaloud Moosa Al Balushi
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK; Department of Engineering, The University of Technology and Applied Sciences, Suhar 311, Oman
| | - Khellil Sefiane
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK
| | - Daniel Orejon
- Institute for Multiscale Thermofluids, School of Engineering, The University of Edinburgh, Edinburgh EH9 3FD, Scotland, UK; International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
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Boudaghi A, Foroutan M. Investigation of the wettability of chemically heterogeneous smooth and rough surfaces using molecular dynamics simulation. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118017] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Tsao HK, Walker GC. Virtual Issue: Wettability Gradient Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:603-604. [PMID: 35038869 DOI: 10.1021/acs.langmuir.1c02940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
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Lowrey S, Misiiuk K, Blaikie R, Sommers A. Survey of Micro/Nanofabricated Chemical, Topographical, and Compound Passive Wetting Gradient Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:605-619. [PMID: 34498455 DOI: 10.1021/acs.langmuir.1c00612] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Surface wetting gradients are desirable due to their ability to passively transport liquid droplets without the aid of gravity. Such surfaces can be prepared through topographical or chemical methods or a compound approach involving both methods. By altering the surface free energy across a surface, a droplet that contacts such a surface will experience an actuation force toward the hydrophilic region. Such transport properties make these surfaces attractive for a range of applications from thermal management to microfluidics to the investigation of biomolecular interactions. This paper reviews passive wetting gradients that have been demonstrated over the last three decades, focusing on the types of surfaces that have been developed to date along with the materials that have been used. The corresponding wetting ranges and physical lengths over which droplet mobility has been achieved on these various types of gradient surfaces are compared to guide future developments.
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Affiliation(s)
- Sam Lowrey
- Department of Physics, University of Otago, Dunedin 9016, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Wellington, Wellington 6012, New Zealand
| | - Kirill Misiiuk
- Department of Physics, University of Otago, Dunedin 9016, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Wellington, Wellington 6012, New Zealand
| | - Richard Blaikie
- Department of Physics, University of Otago, Dunedin 9016, New Zealand
- MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Wellington, Wellington 6012, New Zealand
| | - Andrew Sommers
- Department of Mechanical & Manufacturing Engineering, Miami University, Oxford, Ohio 45056, United States
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Chatterjee S, Murallidharan JS, Agrawal A, Bhardwaj R. Designing antiviral surfaces to suppress the spread of COVID-19. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:052101. [PMID: 34040336 PMCID: PMC8142823 DOI: 10.1063/5.0049404] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Accepted: 03/23/2021] [Indexed: 05/18/2023]
Abstract
Surface engineering is an emerging technology to design antiviral surfaces, especially in the wake of COVID-19 pandemic. However, there is yet no general understanding of the rules and optimized conditions governing the virucidal properties of engineered surfaces. The understanding is crucial for designing antiviral surfaces. Previous studies reported that the drying time of a residual thin-film after the evaporation of a bulk respiratory droplet on a smooth surface correlates with the coronavirus survival time. Recently, we [Chatterjee et al., Phys. Fluids. 33, 021701 (2021)] showed that the evaporation is much faster on porous than impermeable surfaces, making the porous surfaces lesser susceptible to virus survival. The faster evaporation on porous surfaces was attributed to an enhanced disjoining pressure within the thin-film due the presence of horizontally oriented fibers and void spaces. Motivated by this, we explore herein the disjoining pressure-driven thin-film evaporation mechanism and thereby the virucidal properties of engineered surfaces with varied wettability and texture. A generic model is developed which agrees qualitatively well with the previous virus titer measurements on nanostructured surfaces. Thereafter, we design model surfaces and report the optimized conditions for roughness and wettability to achieve the most prominent virucidal effect. We have deciphered that the optimized thin-film lifetime can be gained by tailoring wettability and roughness, irrespective of the nature of texture geometry. The present study expands the applicability of the process and demonstrates ways to design antiviral surfaces, thereby aiding to mitigate the spread of COVID-19.
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Affiliation(s)
- Sanghamitro Chatterjee
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | | | - Amit Agrawal
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rajneesh Bhardwaj
- Department of Mechanical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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