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Akbari R, Ambrosio F, Berry JD, Antonini C. Wetting characterisation on complex surfaces by an automatic open-source tool: DropenVideo. J Colloid Interface Sci 2024; 678:1075-1086. [PMID: 39236436 DOI: 10.1016/j.jcis.2024.08.159] [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: 04/24/2024] [Revised: 07/26/2024] [Accepted: 08/19/2024] [Indexed: 09/07/2024]
Abstract
HYPOTHESIS Investigating solid-liquid interactions to determine advancing and receding contact angles, and consequently contact angle hysteresis, is crucial for understanding material wetting properties. A reliable, automated, and possibly open-source tool is desirable, to standardize and automatize the measurement and make it user-independent. EXPERIMENTS This study introduces an open-source software, DropenVideo, as an extension of Dropen. DropenVideo automates frame-by-frame video analysis for the advancing and receding contact angle determination, by considering needle presence, contrast tuning, and compensating for missing drop edge data. Contact angles are calculated using convolution mask, circle, and polynomial fittings. An innovative feature in DropenVideo is the automatic protocol for identifying advancing and receding contact angles: (i) the advancing contact angle is determined as the average value during drop inflation; and (ii) the receding contact angle is determined from the frame of incipient motion during drop deflation. FINDINGS Exploring the application of DropenVideo across a range of complex surfaces as representative test cases, we highlight existing challenges in interpreting wetting measurements by addressing different wetting scenarios. Our study demonstrates that employing frame-by-frame automatic analysis of contact angle measurement videos using DropenVideo significantly mitigates the potential risks of subjective bias associated with manual interpretation and enhances the precision of identified wetting characteristics.
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Affiliation(s)
- Raziyeh Akbari
- Department of Materials Science, University of Milano-Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
| | - Federico Ambrosio
- Department of Materials Science, University of Milano-Bicocca, via R. Cozzi 55, 20125 Milano, Italy
| | - Joseph D Berry
- School of Chemical and Biomedical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Carlo Antonini
- Department of Materials Science, University of Milano-Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
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Chen K, Li J, Wei C, Oron A, Shan Y, Jiang Y. Soft wetting: Substrate softness- and time-dependent droplet/bubble adhesion. J Colloid Interface Sci 2024; 662:87-98. [PMID: 38340517 DOI: 10.1016/j.jcis.2024.02.037] [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: 11/15/2023] [Revised: 01/16/2024] [Accepted: 02/04/2024] [Indexed: 02/12/2024]
Abstract
HYPOTHESIS The droplet/bubble adhesion characteristics depend on the length of the droplet/bubble three-phase contact line. Since the deformation caused by the liquid-gas interfacial tension on the soft substrate, referred as to the wetting ridge, retards contact line spreading and retraction, we conjecture that the droplet/bubble adhesion characteristics depend also on the substrate softness. EXPERIMENTS Soft substrates with various shear moduli are prepared and characterized by the spreading and receding dynamics of water droplets and underwater bubbles. Snap-in and normal adhesion forces of droplets/bubbles on such soft substrates are directly measured along with the visualized droplet/bubble shape profiles. FINDINGS The droplet/bubble snap-in force, which corresponds to the short-time spreading dynamics, decreases with a decrease in the substrate shear modulus because of the retarded contact line spreading. The droplet maximal adhesion force on a soft substrate can be counterintuitively either smaller or larger than its counterpart on the rigid substrate depending on different dwelling times, i.e., the droplet/bubble-substrate contact time before droplet/bubble-substrate separation. The former is attributed to the retarded contact line spreading, whereas the latter is attributed to the retarded contact line retraction. The substrate softness- and dwelling time-dependent droplet/bubble adhesion reported in this study will benefit various applications related to soft substrates.
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Affiliation(s)
- Kaiyuan Chen
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China; Department of Mechanical Engineering, Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Juan Li
- Department of Mechanical Engineering, Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China; Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Chuanqi Wei
- Department of Mechanical Engineering, Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Alexander Oron
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yanguang Shan
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
| | - Youhua Jiang
- Department of Mechanical Engineering, Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China; Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel; Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China.
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Jiang Y, Wang Z. Soft wetting: an analytical model for pillar topography- and softness-dependent droplet depinning force. SOFT MATTER 2024; 20:3593-3601. [PMID: 38530168 DOI: 10.1039/d4sm00128a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
The extent to which a droplet pins on a textured substrate is determined by the dynamics of the contact line and the liquid-vapor interface. However, the synergistic contribution of contact line sliding and interface distortion to the droplet depinning force remains unknown. More strikingly, current models fail to predict the depinning force per unit length of droplets on soft pillar arrays. Therefore, we fabricate soft pillar arrays with varying geometrical dimensions and mechanical properties and measure the depinning forces per unit length by allowing droplets to evaporate on such substrates. We then analyze the decrease in excess Gibbs free energy of the apparent droplet caused by the detachment of the droplet boundary from the previously pinned pillars. In contrast to prior notions, based on the measured decreases in excess Gibbs free energy, we find that the coefficient, that governs the ratio of interface distortion's contribution to the depinning force to that of the sliding contact line, increases with a decrease in pillar packing density. By considering the combined contribution from contact line sliding, liquid-vapor interface distortion, and pillar deflection, we introduce an analytical model to predict the droplet depinning force per unit length and corroborate the model using experimental data reported in this and prior studies.
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Affiliation(s)
- Youhua Jiang
- Department of Mechanical Engineering (Robotics), Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China.
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Zhujiang Wang
- Department of Mechanical Engineering (Robotics), Guangdong Technion - Israel Institute of Technology, Shantou, Guangdong 515063, China.
- Faculty of Mechanical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
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Jiang Y, Xu Z, Li B, Li J, Guan D. Soft Wetting: Droplet Receding Contact Angles on Soft Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:15401-15408. [PMID: 37857566 DOI: 10.1021/acs.langmuir.3c02667] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2023]
Abstract
Despite intensive investigations on the droplet receding contact angle on superhydrophobic surfaces, i.e., a key parameter characterizing surface wettability and adhesion, the quantitative correlation between the surface structure mechanical properties (softness) and the droplet receding contact angles remains vague. By systematically varying the geometric dimensions and mechanical properties of soft pillar arrays, we find that the droplet receding contact angles decrease with the decrease in the pillar spring constant. Most surprisingly, the densely packed pillar arrays may result in larger receding contact angles than those on sparsely packed pillars, opposing the understanding of rigid pillar arrays, where the receding contact angles increase with a decrease in the packing density of pillars. This is attributed to the collective effects of capillarity and elasticity, where the energy consumed by the sliding contact line, the energy stored in the distorted liquid-vapor interface, and the energy stored in the deflected pillar contribute to the droplet depinning characteristics. We develop an analytical model to predict the droplet receding contact angles on soft superhydrophobic pillar arrays with knowledge of the material intrinsic receding contact angle, the pillar geometry, and the pillar mechanical properties. The predictions are corroborated by the experimental data measured in this and prior studies.
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Affiliation(s)
- Youhua Jiang
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
- Faculty of Mechanical Engineering, Technion─Israel Institute of Technology, Haifa 3200003, Israel
- Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Zhijia Xu
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Bin Li
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
- Faculty of Mechanical Engineering, Technion─Israel Institute of Technology, Haifa 3200003, Israel
- Guangdong Provincial Key Laboratory of Materials and Technologies for Energy Conversion, Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
| | - Juan Li
- Department of Mechanical Engineering (Robotics), Guangdong Technion─Israel Institute of Technology, Shantou, Guangdong 515063, China
- Faculty of Mechanical Engineering, Technion─Israel Institute of Technology, Haifa 3200003, Israel
| | - Dongshi Guan
- State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
- School of Engineering Science, University of Chinese Academy of Sciences, Beijing 100049, China
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Sammartino C, Shokef Y, Pinchasik BE. Percolation in Networks of Liquid Diodes. J Phys Chem Lett 2023; 14:7697-7702. [PMID: 37606508 PMCID: PMC10476187 DOI: 10.1021/acs.jpclett.3c01885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/04/2023] [Indexed: 08/23/2023]
Abstract
Liquid diodes are surface structures that facilitate the spontaneous flow of liquids in a specific direction. In nature, they are used to increase water collection and uptake, reproduction, and feeding. However, large networks with directional properties are exceptional and are typically limited up to a few centimeters. Here, we simulate, design, and 3D print liquid diode networks consisting of hundreds of unit cells. We provide structural and wettability guidelines for directional transport of liquids through these networks and introduce percolation theory in order to identify the threshold between a connected network, which allows fluid to reach specific points, and a disconnected network. By constructing well-defined networks with uni- and bidirectional pathways, we experimentally demonstrate the applicability of models describing isotropically directed percolation. We accurately predict the network permeability and the liquid final state. These guidelines are highly promising for the development of structures for spontaneous, yet predictable, directional liquid transport.
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Affiliation(s)
- Camilla Sammartino
- School
of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
| | - Yair Shokef
- School
of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 69978, Israel
- Center
for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978, Israel
- International
Institute for Sustainability with Knotted Chiral Meta Matter, Hiroshima University, Hiroshima 739-8511, Japan
| | - Bat-El Pinchasik
- School
of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
- Center
for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 69978, Israel
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Feldmann D, Pinchasik BE. The temperature dependent dynamics and periodicity of dropwise condensation on surfaces with wetting heterogeneities. J Colloid Interface Sci 2023; 644:146-156. [PMID: 37105038 DOI: 10.1016/j.jcis.2023.04.060] [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: 04/14/2022] [Revised: 04/07/2023] [Accepted: 04/13/2023] [Indexed: 04/29/2023]
Abstract
HYPOTHESIS Biphilic surfaces, namely surfaces comprising hydrophilic areas with a (super)hydrophobic background, are used in nature and engineering for controlled dropwise condensation and liquid transport. These, however, are highly dependent on the surface temperature and subcooling. EXPERIMENTS Here, biphilic surfaces were cooled inside a rotatable environmental chamber under controlled humidity. The condensation dynamics on the surface was quantified, depending on the subcooling, and compared to uniform superhydrophobic (USH) surfaces. Rates of condensation and transport were analyzed in terms of droplet number and size, covered area and fluid volume over several length scales. Specifically, from microscale condensation to macroscale droplet roll-off. FINDINGS Four phases of condensation were identified: a) initial nucleation, b) droplets on single patches, c) droplets covering adjacent patches and d) multi-patch droplets. Only the latter become mobile and roll off the surface. Cooling the surface to temperatures between T = 2-16 °C shows that lowering the temperature shortens some of the condensation parameters linearly, while others follow a power law, as expected from the theory of condensation. The temperature dependent condensation dynamics on (super)biphilic surfaces is faster in comparison to uniform superhydrophobic surfaces. Nevertheless, within time intervals of a few hours, droplets are mostly immobile. This sets guiding lines for using biphilic surfaces in applications such as water collection, heat transfer and separation processes. Generally, biphilic surfaces are suitable for applications in which fluids should be collected, concentrated and immobilized in specific areas.
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Affiliation(s)
- David Feldmann
- Tel Aviv University School of Mechanical Engineering, Faculty of Engineering, Ramat Aviv 69978, Tel-Aviv, Israel
| | - Bat-El Pinchasik
- Tel Aviv University School of Mechanical Engineering, Faculty of Engineering, Ramat Aviv 69978, Tel-Aviv, Israel.
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Shyam S, Misra S, Mitra SK. A UNIVERSAL CAPILLARY-DEFLECTION BASED ADHESION MEASUREMENT TECHNIQUE. J Colloid Interface Sci 2022; 630:322-333. [DOI: 10.1016/j.jcis.2022.09.140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 09/22/2022] [Accepted: 09/26/2022] [Indexed: 10/06/2022]
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