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Shamim JA, Takahashi Y, Goswami A, Shaukat N, Hsu WL, Choi J, Daiguji H. Suppression of wetting transition on evaporative fakir droplets by using slippery superhydrophobic surfaces with low depinning force. Sci Rep 2023; 13:2368. [PMID: 36759577 PMCID: PMC9911698 DOI: 10.1038/s41598-023-29163-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 01/31/2023] [Indexed: 02/11/2023] Open
Abstract
This study experimentally investigated the evaporation and wetting transition behavior of fakir droplets on five different microstructured surfaces. Diamond-like carbon was introduced as the substrate, and the influence of varying the width, height, and pitch of the micropillars was assessed. The experimental results showed that the interfacial properties of the surfaces change the evaporation behavior and the starting point of the wetting transition. An important result of this study is the demonstration of a slippery superhydrophobic surface with low depinning force that suppresses the transition from the Cassie-Baxter state to the Wenzel state for microdroplets less than 0.37 mm in diameter, without employing large pillar height or multiscale roughness. By selecting an appropriate pillar pitch and employing tapered micropillars with small pillar widths, the solid-liquid contact at the three-phase contact line was reduced and low depinning forces were obtained. The underlying mechanism by which slippery superhydrophobic surfaces suppress wetting transitions is also discussed. The accuracy of the theoretical models for predicting the critical transition parameters was assessed, and a numerical model was developed in the surface evolver to compute the penetration of the droplet bottom meniscus within the micropillars.
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Affiliation(s)
- Jubair A. Shamim
- grid.26999.3d0000 0001 2151 536XDepartment of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-8656 Japan
| | - Yukinari Takahashi
- grid.26999.3d0000 0001 2151 536XDepartment of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-8656 Japan
| | - Anjan Goswami
- grid.7445.20000 0001 2113 8111Department of Mechanical Engineering, Imperial College London, London, SW7 2AZ UK
| | - Nadeem Shaukat
- grid.420112.40000 0004 0607 7017Center for Mathematical Sciences, Pakistan Institute of Engineering and Applied Sciences, Nilore, 45650 Islamabad Pakistan
| | - Wei-Lun Hsu
- grid.26999.3d0000 0001 2151 536XDepartment of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-8656 Japan
| | - Junho Choi
- grid.26999.3d0000 0001 2151 536XDepartment of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-8656 Japan
| | - Hirofumi Daiguji
- Department of Mechanical Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-Ku, Tokyo, 113-8656, Japan.
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Mehanna YA, Sadler E, Upton RL, Kempchinsky AG, Lu Y, Crick CR. The challenges, achievements and applications of submersible superhydrophobic materials. Chem Soc Rev 2021; 50:6569-6612. [PMID: 33889879 DOI: 10.1039/d0cs01056a] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Superhydrophobic materials have been widely reported throughout the scientific literature. Their properties originate from a highly rough morphology and inherently water repellent surface chemistry. Despite promising an array of functionalities, these materials have seen limited commercial development. This could be attributed to many factors, like material compatibility, low physical resilience, scaling-up complications, etc. In applications where persistent water contact is required, another limitation arises as a major concern, which is the stability of the air layer trapped at the surface when submerged or impacted by water. This review is aimed at examining the diverse array of research focused on monitoring/improving air layer stability, and highlighting the most successful approaches. The reported complexity of monitoring and enhancing air layer stability, in conjunction with the variety of approaches adopted, results in an assortment of suggested routes to achieving success. The review is addressing the challenge of finding a balance between maximising water repulsion and incorporating structures that protect air pockets from removal, along with challenges related to the variant approaches to testing air-layer stability across the research field, and the gap between the achieved progress and the required performance in real-life applications.
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Affiliation(s)
- Yasmin A Mehanna
- Materials Innovation Factory, Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK
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Esmaeilzadeh H, Zheng K, Barry C, Mead J, Charmchi M, Sun H. Evaluating Superhydrophobic Surfaces under External Pressures using Quartz Crystal Microbalance. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6650-6659. [PMID: 34038126 DOI: 10.1021/acs.langmuir.1c00478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The performance of hydrophobic surfaces under hydraulic pressures is critical to a wide range of practical applications such as drag reduction of seaboard vessels and design of microfluidic devices. This research focuses on the evaluation of drag reduction and velocity slip of hydrophobic surfaces and coatings under external hydrostatic pressures using an acoustic wave device (i.e., quartz crystal microbalance, QCM). The correlation between the resonant frequency shift of a QCM device and drag reduction of hydrophobic surface coated on the QCM was theoretically developed and the model was validated by comparing the measurement results of the drag reduction of an epoxy-based superhydrophobic coating with those measured by a rheometer. The QCM device was further employed to study the wetting state transition and drag reduction of water on a micropillar array based superhydrophobic surface under elevated hydrostatic pressures. It was found that the transition from Cassie to Wenzel states occurred at a critical hydrostatic pressure which was indicated by a sudden frequency drop of the QCM device. In addition, the effective heights of the meniscus at the liquid/air interface increased with the external pressure before the transition took place. The drag reduction induced by the micropillar surface decreased with the increasing hydrostatic pressures. It was demonstrated that the developed QCM based technology provides a low cost, simple, and reliable tool for evaluating hydrophobic performance of various surfaces under external hydrostatic pressures.
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Affiliation(s)
| | | | | | | | | | - Hongwei Sun
- Department of Mechanical and Industrial Engineering Northeastern University, Boston, Massachusetts 02115, United States
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Zhang D, Takase S, Nagayama G. Measurement of effective wetting area at hydrophobic solid-liquid interface. J Colloid Interface Sci 2021; 591:474-482. [PMID: 33640849 DOI: 10.1016/j.jcis.2021.01.056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 12/31/2020] [Accepted: 01/19/2021] [Indexed: 10/22/2022]
Abstract
HYPOTHESES The effective wetting area, a parameter somewhat different from the apparent contact area at solid-liquid interfaces, plays a significant role in surface wettability. However, determination of the effective wetting area for hydrophobic surfaces remains an open question. In the present study, we developed an electrochemical impedance method to evaluate the effective wetting area at a hydrophobic solid-liquid interface. EXPERIMENTS Patterned Si surfaces were prepared using the anisotropic wet etching method, and the water contact angle and electrochemical impedance were measured experimentally. The effective wetting area at the solid-liquid interface was examined based on the wettability and impedance results. FINDINGS The electrochemical impedance for the patterned Si surfaces increased with increasing surface hydrophobicity, whereas the effective wetting area decreased. The intermediate wetting state (i.e. partial wetting model) was confirmed at the patterned Si surfaces, and the effective wetting area was theoretically estimated. The effective wetting area predicted from the electrochemical impedance agreed well with that predicted from the partial wetting model, thereby demonstrating the validity of the electrochemical impedance method for evaluating the effective wetting area at the hydrophobic solid-liquid interface.
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Affiliation(s)
- Dejian Zhang
- Department of Mechanical Engineering, Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu, Fukuoka 804-8550, Japan
| | - Satoko Takase
- Department of Chemical Engineering, Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu, Fukuoka 804-8550, Japan
| | - Gyoko Nagayama
- Department of Mechanical Engineering, Kyushu Institute of Technology, Sensui 1-1, Tobata, Kitakyushu, Fukuoka 804-8550, Japan.
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Yu N, Kiani S, Xu M, Kim CJC. Brightness of Microtrench Superhydrophobic Surfaces and Visual Detection of Intermediate Wetting States. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:1206-1214. [PMID: 33428410 DOI: 10.1021/acs.langmuir.0c03172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
For a superhydrophobic (SHPo) surface under water, the dewetted or wetted states are easily distinguishable by the bright silvery plastron or lack of it, respectively. However, to detect an intermediate state between the two, where water partially intrudes the surface roughness, a special visualization technique has been needed. Focusing on SHPo surfaces of parallel microtrenches and considering drag reduction as a prominent application, we (i) show the reliance on surface brightness alone may seriously mislead the wetting state, (ii) theorize how the brightness is determined by water intrusion depth and viewing direction, (iii) support the theory experimentally with confocal microscopy and CCD cameras, (iv) present how to estimate the intrusion depth using optical images taken from different angles, and (v) showcase how to detect intermediate states slightly off the properly dewetted state by simply looking. The proposed method would allow monitoring SHPo trench surfaces without bulky instruments-especially useful for large samples and field tests.
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Affiliation(s)
- Ning Yu
- Mechanical and Aerospace Engineering Department, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Sarina Kiani
- Mechanical and Aerospace Engineering Department, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Muchen Xu
- Mechanical and Aerospace Engineering Department, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Chang-Jin Cj Kim
- Mechanical and Aerospace Engineering Department, University of California, Los Angeles, Los Angeles, California 90095, United States
- Bioengineering Department, University of California, Los Angeles, Los Angeles, California 90095, United States
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, California 90095, United States
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Leppin C, Hampel S, Meyer FS, Langhoff A, Fittschen UEA, Johannsmann D. A Quartz Crystal Microbalance, Which Tracks Four Overtones in Parallel with a Time Resolution of 10 Milliseconds: Application to Inkjet Printing. SENSORS (BASEL, SWITZERLAND) 2020; 20:E5915. [PMID: 33092072 PMCID: PMC7589769 DOI: 10.3390/s20205915] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 10/12/2020] [Accepted: 10/15/2020] [Indexed: 01/26/2023]
Abstract
A quartz crystal microbalance (QCM) is described, which simultaneously determines resonance frequency and bandwidth on four different overtones. The time resolution is 10 milliseconds. This fast, multi-overtone QCM is based on multi-frequency lockin amplification. Synchronous interrogation of overtones is needed, when the sample changes quickly and when information on the sample is to be extracted from the comparison between overtones. The application example is thermal inkjet-printing. At impact, the resonance frequencies change over a time shorter than 10 milliseconds. There is a further increase in the contact area, evidenced by an increasing common prefactor to the shifts in frequency, Δf, and half-bandwidth, ΔΓ. The ratio ΔΓ/(-Δf), which quantifies the energy dissipated per time and unit area, decreases with time. Often, there is a fast initial decrease, lasting for about 100 milliseconds, followed by a slower decrease, persisting over the entire drying time (a few seconds). Fitting the overtone dependence of Δf(n) and ΔΓ(n) with power laws, one finds power-law exponents of about 1/2, characteristic of semi-infinite Newtonian liquids. The power-law exponents corresponding to Δf(n) slightly increase with time. The decrease of ΔΓ/(-Δf) and the increase of the exponents are explained by evaporation and formation of a solid film at the resonator surface.
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Affiliation(s)
- Christian Leppin
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
| | - Sven Hampel
- Institute of Inorganic and Analytical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (S.H.); (U.E.A.F.)
| | - Frederick Sebastian Meyer
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
| | - Arne Langhoff
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
| | - Ursula Elisabeth Adriane Fittschen
- Institute of Inorganic and Analytical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (S.H.); (U.E.A.F.)
| | - Diethelm Johannsmann
- Institute of Physical Chemistry, Clausthal University of Technology, Arnold-Sommerfeld-Str. 4, D-38678 Clausthal-Zellerfeld, Germany; (C.L.); (F.S.M.); (A.L.)
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Li X, Yang J, Lv K, Papadopoulos P, Sun J, Wang D, Zhao Y, Chen L, Wang D, Wang Z, Deng X. Salvinia-like slippery surface with stable and mobile water/air contact line. Natl Sci Rev 2020; 8:nwaa153. [PMID: 34691630 PMCID: PMC8288347 DOI: 10.1093/nsr/nwaa153] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/04/2020] [Accepted: 06/07/2020] [Indexed: 11/13/2022] Open
Abstract
Superhydrophobic surfaces are widely used in many industrial settings, and mainly consist of rough solid protrusions that entrap air to minimize the liquid/solid area. The stability of the superhydrophobic state favors relatively small spacing between protrusions. However, this in turn increases the lateral adhesion force that retards the mobility of drops. Here we propose a novel approach that optimizes both properties simultaneously. Inspired by the hydrophobic leaves of Salvinia molesta and the slippery Nepenthes pitcher plants, we designed a Salvinia-like slippery surface (SSS) consisting of protrusions with slippery heads. We demonstrate that compared to a control surface, the SSS exhibits increased stability against pressure and impact, and enhanced lateral mobility of water drops as well as reduced hydrodynamic drag. We also systematically investigate the wetting dynamics on the SSS. With its easy fabrication and enhanced performance, we envision that SSS will be useful in a variety of fields in industry.
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Affiliation(s)
- Xiaomei Li
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Jinlong Yang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Kaixuan Lv
- State Key Laboratory of Polymer Physics and Chemistry, Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | | | - Jing Sun
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Dehui Wang
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Yanhua Zhao
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Longquan Chen
- School of Physics, University of Electronic Science and Technology of China, Chengdu 610054, China
| | - Dapeng Wang
- State Key Laboratory of Polymer Physics and Chemistry, Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, China
| | - Zuankai Wang
- Department of Mechanical Engineering, City University of Hong Kong, Hong Kong, China
| | - Xu Deng
- Institute of Fundamental and Frontier Sciences, University of Electronic Science and Technology of China, Chengdu 610054, China
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Narkar AR, Kendrick C, Bellur K, Leftwich T, Zhang Z, Lee BP. Rapidly responsive smart adhesive-coated micropillars utilizing catechol-boronate complexation chemistry. SOFT MATTER 2019; 15:5474-5482. [PMID: 31237299 PMCID: PMC6776246 DOI: 10.1039/c9sm00649d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Smart adhesive hydrogels containing 10 mol% each of dopamine methacrylamide (DMA) and 3-acrylamido phenylboronic acid (APBA) were polymerized in situ onto polydimethylsiloxane (PMDS) micropillars with different aspect ratios (AR = 0.4, 1 and 2). Using Johnson-Kendall-Roberts (JKR) contact mechanics tests, the adhesive-coated pillars demonstrated strong wet adhesion at pH 3 (Wadh = 420 mJ m-2) and can be repeatedly deactivated and reactivated by changing the pH value (pH 9 and 3, respectively). When compared to the bulk adhesive hydrogel of the same composition, the adhesive-coated pillars exhibited a significantly faster rate of transition (1 min) between strong and weak adhesion. This was attributed to an increased surface area to volume ratio of the adhesive hydrogel-coated pillars, which permitted rapid diffusion of ions into the adhesive matrix to form or break the catechol-boronate complex.
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Affiliation(s)
- Ameya R Narkar
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931, USA.
| | - Chito Kendrick
- Department of Electrical and Computer Engineering, Michigan Technological University, Houghton, MI 49931, USA
| | - Kishan Bellur
- Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931, USA
| | - Timothy Leftwich
- Department of Materials Science and Engineering, Michigan Technological University, Houghton, MI 49931, USA
| | - Zhongtian Zhang
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931, USA.
| | - Bruce P Lee
- Department of Biomedical Engineering, Michigan Technological University, Houghton, MI 49931, USA.
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Thermal Characterisation of Micro Flat Aluminium Heat Pipe Arrays by Varying Working Fluid and Inclination Angle. APPLIED SCIENCES-BASEL 2018. [DOI: 10.3390/app8071052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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