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Zhang S, Zhao L, Yu M, Guo J, Liu C, Zhu C, Zhao M, Huang Y, Zheng Y. Measurement Methods for Droplet Adhesion Characteristics and Micrometer-Scale Quantification of Contact Angle on Superhydrophobic Surfaces: Challenges and Opportunities. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:9873-9891. [PMID: 38695884 DOI: 10.1021/acs.langmuir.3c03967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2024]
Abstract
Inspired by nature, superhydrophobic surfaces have been widely studied. Usually the wettability of a superhydrophobic surface is quantified by the macroscopic contact angle. However, this method has various limitations, especially for precision micro devices with superhydrophobic surfaces, such as biomimetic artificial compound eyes and biomimetic water strider robots. These precision micro devices with superhydrophobic surfaces proposed a higher demand for the quantification of contact angles, requiring contact angle quantification technology to have micrometer-scale measurement capabilities. In this review, it is proposed to achieve micrometer-scale quantification of superhydrophobic surface contact angles through droplet adhesion characteristics (adhesion force and contact radius). Existing contact angle quantification techniques and droplet characteristics' measurement methods were described in detail. The advancement of micrometer-scale quantification technology for the contact angle of superhydrophobic surfaces will enhance our understanding of superhydrophobic surfaces.
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Affiliation(s)
- Shiyu Zhang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Lingzhe Zhao
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Meike Yu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Jinwei Guo
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Chuntian Liu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Chunyuan Zhu
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Meirong Zhao
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Yinguo Huang
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
| | - Yelong Zheng
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, People's Republic of China
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2
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Backholm M, Kärki T, Nurmi HA, Vuckovac M, Turkki V, Lepikko S, Jokinen V, Quéré D, Timonen JVI, Ras RHA. Toward vanishing droplet friction on repellent surfaces. Proc Natl Acad Sci U S A 2024; 121:e2315214121. [PMID: 38621127 PMCID: PMC11047067 DOI: 10.1073/pnas.2315214121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 03/08/2024] [Indexed: 04/17/2024] Open
Abstract
Superhydrophobic surfaces are often seen as frictionless materials, on which water is highly mobile. Understanding the nature of friction for such water-repellent systems is central to further minimize resistance to motion and energy loss in applications. For slowly moving drops, contact-line friction has been generally considered dominant on slippery superhydrophobic surfaces. Here, we show that this general rule applies only at very low speed. Using a micropipette force sensor in an oscillating mode, we measure the friction of water drops approaching or even equaling zero contact-line friction. We evidence that dissipation then mainly stems from the viscous shearing of the air film (plastron) trapped under the liquid. Because this force is velocity dependent, it can become a serious drag on surfaces that look highly slippery from quasi-static tests. The plastron thickness is found to be the key parameter that enables the control of this special friction, which is useful information for designing the next generation of ultraslippery water-repellent coatings.
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Affiliation(s)
- Matilda Backholm
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Tytti Kärki
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Heikki A. Nurmi
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Maja Vuckovac
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Valtteri Turkki
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Sakari Lepikko
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Ville Jokinen
- Department of Chemistry and Materials Science, Aalto University, Espoo02150, Finland
| | - David Quéré
- Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, Paris Sciences Lettres Research University, Ecole Supérieure de Physique et Chimie Industrielles, Paris75005, France
| | - Jaakko V. I. Timonen
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
| | - Robin H. A. Ras
- Department of Applied Physics, Aalto University, Espoo02150, Finland
- Centre of Excellence in Life-Inspired Hybrid Materials, Aalto University, Espoo02150, Finland
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3
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Hinduja C, Butt HJ, Berger R. Slide electrification of drops at low velocities. SOFT MATTER 2024; 20:3349-3358. [PMID: 38563221 PMCID: PMC11022544 DOI: 10.1039/d4sm00019f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2024] [Accepted: 03/13/2024] [Indexed: 04/04/2024]
Abstract
Slide electrification of drops is mostly investigated on tilted plate setups. Hence, the drop charging at low sliding velocity remains unclear. We overcome the limitations by developing an electro drop friction force instrument (eDoFFI). Using eDoFFI, we investigate slide electrification at the onset of drop sliding and at low sliding velocities ≤ 1 cm s-1. The novelty of eDoFFI is the simultaneous measurements of the drop discharging current and the friction force acting on the drop. The eDoFFI tool facilitates control on drop length and width using differently shaped rings. Hereby, slide electrification experiments with the defined drop length-to-width ratios >1 and <1 are realized. We find that width of the drop is the main geometrical parameter which determines drop discharging current and charge separation. We combine Kawasaki-Furmidge friction force equation with our finding on drop discharging current. This combination facilitates the direct measurement of surface charge density (σ) deposited behind the drop. We calculate σ ≈ 45 μC m-2 on Trichloro(1H,1H,2H,2H-perfluorooctyl)silane (PFOTS) and ≈20 μC m-2 on Trichloro(octyl)silane (OTS) coated glass surfaces. We find that the charge separation by moving drops is independent of sliding velocity ≤ 1 cm s-1. The reverse sliding of drop along the same scanline facilitates calculation of the surface neutralization time constant. The eDoFFI links two scientific communities: one which focuses on the friction forces and one which focuses on the slide electrification of drops.
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Affiliation(s)
- Chirag Hinduja
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany.
| | - Hans-Jürgen Butt
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany.
| | - Rüdiger Berger
- Max Planck Institute for Polymer Research, 55128 Mainz, Germany.
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4
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Hinduja C, Laroche A, Shumaly S, Wang Y, Vollmer D, Butt HJ, Berger R. Scanning Drop Friction Force Microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:14635-14643. [PMID: 36399702 PMCID: PMC9730904 DOI: 10.1021/acs.langmuir.2c02046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Wetting imperfections are omnipresent on surfaces. They cause contact angle hysteresis and determine the wetting dynamics. Still, existing techniques (e.g., contact angle goniometry) are not sufficient to localize inhomogeneities and image wetting variations. We overcome these limitations through scanning drop friction force microscopy (sDoFFI). In sDoFFI, a 15 μL drop of Milli-Q water is raster-scanned over a surface. The friction force (lateral adhesion force) acting on the moving contact line is plotted against the drop position. Using sDoFFI, we obtained 2D wetting maps of the samples having sizes in the order of several square centimeters. We mapped areas with distinct wetting properties such as those present on a natural surface (e.g., a rose petal), a technically relevant superhydrophobic surface (e.g., Glaco paint), and an in-house prepared model of inhomogeneous surfaces featuring defined areas with low and high contact angle hysteresis. sDoFFI detects features that are smaller than 0.5 mm in size. Furthermore, we quantified the sliding behavior of drops across the boundary separating areas with different contact angles on the model sample. The sliding of a drop across this transition line follows a characteristic stick-slip motion. We use the variation in force signals, advancing and receding contact line velocities, and advancing and receding contact angles to identify zones of stick and slip. When scanning the drop from low to high contact angle hysteresis, the drop undergoes a stick-slip-stick-slip motion at the interline. Sliding from high to low contact angle hysteresis is characterized by the slip-stick-slip motion. The sDoFFI is a new tool for 2D characterization of wetting properties, which is applicable to laboratory-based samples but also characterizes biological and commercial surfaces.
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Affiliation(s)
- Chirag Hinduja
- Max
Planck Institute for Polymer Research, Mainz 55128, Germany
| | - Alexandre Laroche
- Max
Planck Institute for Polymer Research, Mainz 55128, Germany
- University
of Zurich, Winterthurerstrasse
190, Zurich 8057, Switzerland
| | - Sajjad Shumaly
- Max
Planck Institute for Polymer Research, Mainz 55128, Germany
| | - Yujiao Wang
- Key
Laboratory of Interfacial Physics and Technology, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Doris Vollmer
- Max
Planck Institute for Polymer Research, Mainz 55128, Germany
| | | | - Rüdiger Berger
- Max
Planck Institute for Polymer Research, Mainz 55128, Germany
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5
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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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6
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Xu P, Zhang Y, Li L, Lin Z, Zhu B, Chen W, Li G, Liu H, Xiao K, Xiong Y, Yang S, Lei Y, Xue L. Adhesion behaviors of water droplets on bioinspired superhydrophobic surfaces. BIOINSPIRATION & BIOMIMETICS 2022; 17:041003. [PMID: 35561670 DOI: 10.1088/1748-3190/ac6fa5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 05/13/2022] [Indexed: 06/15/2023]
Abstract
The adhesion behaviors of droplets on surfaces are attracting increasing attention due to their various applications. Many bioinspired superhydrophobic surfaces with different adhesion states have been constructed in order to mimic the functions of natural surfaces such as a lotus leaf, a rose petal, butterfly wings, etc. In this review, we first present a brief introduction to the fundamental theories of the adhesion behaviors of droplets on various surfaces, including low adhesion, high adhesion and anisotropic adhesion states. Then, different techniques to characterize droplet adhesion on these surfaces, including the rotating disk technique, the atomic force microscope cantilever technique, and capillary sensor-based techniques, are described. Wetting behaviors, and the switching between different adhesion states on bioinspired surfaces, are also summarized and discussed. Subsequently, the diverse applications of bioinspired surfaces, including water collection, liquid transport, drag reduction, and oil/water separation, are discussed. Finally, the challenges of using liquid adhesion behaviors on various surfaces, and future applications of these surfaces, are discussed.
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Affiliation(s)
- Peng Xu
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Yurong Zhang
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Lijun Li
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Zhen Lin
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Bo Zhu
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Wenhui Chen
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Gang Li
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Hongtao Liu
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Kangjian Xiao
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Yunhe Xiong
- Urology Department, Renmin Hospital of Wuhan University, Zhangzhidong Road 99, 430060, Wuhan, Hubei Province, People's Republic of China
| | - Sixing Yang
- Urology Department, Renmin Hospital of Wuhan University, Zhangzhidong Road 99, 430060, Wuhan, Hubei Province, People's Republic of China
| | - Yifeng Lei
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
| | - Longjian Xue
- School of Power and Mechanical Engineering, The Institute of Technological Science, Wuhan University, South Donghu Road 8, 430072, Wuhan, Hubei Province, People's Republic of China
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7
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Butt HJ, Liu J, Koynov K, Straub B, Hinduja C, Roismann I, Berger R, Li X, Vollmer D, Steffen W, Kappl M. Contact angle hysteresis. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101574] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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8
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Tadmor R. Open Problems in Wetting Phenomena: Pinning Retention Forces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6357-6372. [PMID: 34008988 DOI: 10.1021/acs.langmuir.0c02768] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We review existing explanations for drop pinning and the origin of the force required to initiate the sliding of a drop on a solid surface (depinning). Theories that describe these phenomena include de Gennes', Marmur's, Furmidge's, the related Furmidge-Extrand's, and Tadmor's theory. These theories are all well cited but generally do not address each other, and usually papers that cite one of them ignore the others. Here, we discuss the advantages and disadvantages of these theories and their applicability to different experimental systems. Thus, we link different experimental systems to the theories that describe them best. We describe the force laws that can be deduced should these theories be united and the major open problems that remain. We describe a physical meaning that can be extracted from retention force measurements, specifically, the interfacial modulus that describes the tendency of a solid to conform to the liquid. This has implications for various wetting phenomena such as adhesion robustness, drug penetration into biological tissues, and solid robustness/resilience versus solid degradation over time as a result of its contact with a liquid.
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Affiliation(s)
- Rafael Tadmor
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel
- Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont Texas 77710, United States
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9
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Zhang Y, Wang Y, Tang C, Zhou G, Yu J, He H, Qi H. Reducing the droplet/solid interfacial sliding resistance under electrowetting-on-dielectric by different voltage slew rate signals. Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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10
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Wu H, Dey R, Siretanu I, van den Ende D, Shui L, Zhou G, Mugele F. Electrically Controlled Localized Charge Trapping at Amorphous Fluoropolymer-Electrolyte Interfaces. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1905726. [PMID: 31823510 DOI: 10.1002/smll.201905726] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 11/13/2019] [Indexed: 05/12/2023]
Abstract
Charge trapping is a long-standing problem in electrowetting on dielectric, causing reliability reduction and restricting its practical applications. Although this phenomenon is investigated macroscopically, the microscopic investigations are still lacking. In this work, the trapped charges are proven to be localized at the three-phase contact line (TPCL) region by using three detecting methods-local contact angle measurements, electrowetting (EW) probe, and Kelvin probe force microscopy. Moreover, it is demonstrated that this EW-assisted charge injection (EWCI) process can be utilized as a simple and low-cost method to deposit charges on fluoropolymer surfaces. Charge densities near the TPCL up to 0.46 mC m-2 and line widths of the deposited charge ranging from 20 to 300 µm are achieved by the proposed EWCI method. Particularly, negative charge densities do not degrade even after a "harsh" testing with a water droplet on top of the sample surfaces for 12 h, as well as after being treated by water vapor for 3 h. These findings provide an approach for applications which desire stable and controllable surface charges.
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Affiliation(s)
- Hao Wu
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- Physics of Complex Fluids, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, Enschede, 7500AE, the Netherlands
| | - Ranabir Dey
- Physics of Complex Fluids, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, Enschede, 7500AE, the Netherlands
- Dynamics of Complex Fluids, Max Planck Institute for Dynamics and Self-organization, Am Fassberg 17, Goettingen, 37077, Germany
| | - Igor Siretanu
- Physics of Complex Fluids, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, Enschede, 7500AE, the Netherlands
| | - Dirk van den Ende
- Physics of Complex Fluids, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, Enschede, 7500AE, the Netherlands
| | - Lingling Shui
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
| | - Guofu Zhou
- Guangdong Provincial Key Laboratory of Optical Information Materials and Technology & Institute of Electronic Paper Displays, South China Academy of Advanced Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- National Center for International Research on Green Optoelectronics, South China Normal University, Guangzhou, 510006, P. R. China
- Shenzhen Guohua Optoelectronics Tech. Co. Ltd., Shenzhen, 518110, P. R. China
| | - Frieder Mugele
- Physics of Complex Fluids, Faculty of Science and Technology, MESA+ Institute for Nanotechnology, University of Twente, Enschede, 7500AE, the Netherlands
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11
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Daniel D, Lay CL, Sng A, Jun Lee CJ, Jin Neo DC, Ling XY, Tomczak N. Mapping micrometer-scale wetting properties of superhydrophobic surfaces. Proc Natl Acad Sci U S A 2019; 116:25008-25012. [PMID: 31772014 PMCID: PMC6911201 DOI: 10.1073/pnas.1916772116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
There is a huge interest in developing superrepellent surfaces for antifouling and heat-transfer applications. To characterize the wetting properties of such surfaces, the most common approach is to place a millimetric-sized droplet and measure its contact angles. The adhesion and friction forces can then be inferred indirectly using Furmidge's relation. While easy to implement, contact angle measurements are semiquantitative and cannot resolve wetting variations on a surface. Here, we attach a micrometric-sized droplet to an atomic force microscope cantilever to directly measure adhesion and friction forces with nanonewton force resolutions. We spatially map the micrometer-scale wetting properties of superhydrophobic surfaces and observe the time-resolved pinning-depinning dynamics as the droplet detaches from or moves across the surface.
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Affiliation(s)
- Dan Daniel
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, Singapore 138634;
| | - Chee Leng Lay
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, Singapore 138634
| | - Anqi Sng
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, Singapore 138634
| | - Coryl Jing Jun Lee
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, Singapore 138634
| | - Darren Chi Jin Neo
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, Singapore 138634
| | - Xing Yi Ling
- Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371
| | - Nikodem Tomczak
- Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Innovis, Singapore 138634
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12
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Micropipette force sensors for in vivo force measurements on single cells and multicellular microorganisms. Nat Protoc 2019; 14:594-615. [PMID: 30697007 DOI: 10.1038/s41596-018-0110-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Measuring forces from the piconewton to millinewton range is of great importance for the study of living systems from a biophysical perspective. The use of flexible micropipettes as highly sensitive force probes has become established in the biophysical community, advancing our understanding of cellular processes and microbial behavior. The micropipette force sensor (MFS) technique relies on measurement of the forces acting on a force-calibrated, hollow glass micropipette by optically detecting its deflections. The MFS technique covers a wide micro- and mesoscopic regime of detectable forces (tens of piconewtons to millinewtons) and sample sizes (micrometers to millimeters), does not require gluing of the sample to the cantilever, and allows simultaneous optical imaging of the sample throughout the experiment. Here, we provide a detailed protocol describing how to manufacture and calibrate the micropipettes, as well as how to successfully design, perform, and troubleshoot MFS experiments. We exemplify our approach using the model nematode Caenorhabditis elegans, but by following this protocol, a wide variety of living samples, ranging from single cells to multicellular aggregates and millimeter-sized organisms, can be studied in vivo, with a force resolution as low as 10 pN. A skilled (under)graduate student can master the technique in ~1-2 months. The whole protocol takes ~1-2 d to finish.
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13
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14
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15
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Onset of sliding motion in sessile drops with initially non-circular contact lines. Colloids Surf A Physicochem Eng Asp 2016. [DOI: 10.1016/j.colsurfa.2016.03.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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16
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Pit AM, de Ruiter R, Kumar A, Wijnperlé D, Duits MHG, Mugele F. High-throughput sorting of drops in microfluidic chips using electric capacitance. BIOMICROFLUIDICS 2015; 9:044116. [PMID: 26339316 PMCID: PMC4537480 DOI: 10.1063/1.4928452] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 07/30/2015] [Indexed: 05/11/2023]
Abstract
We analyze a recently introduced approach for the sorting of aqueous drops with biological content immersed in oil, using a microfluidic chip that combines the functionality of electrowetting with the high throughput of two-phase flow microfluidics. In this electrostatic sorter, three co-planar electrodes covered by a thin dielectric layer are placed directly below the fluidic channel. Switching the potential of the central electrode creates an electrical guide that leads the drop to the desired outlet. The generated force, which deflects the drop, can be tuned via the voltage. The working principle is based on a contrast in conductivity between the drop and the continuous phase, which ensures successful operation even for drops of highly conductive biological media like phosphate buffered saline. Moreover, since the electric field does not penetrate the drop, its content is protected from electrical currents and Joule heating. A simple capacitive model allows quantitative prediction of the electrostatic forces exerted on drops. The maximum achievable sorting rate is determined by a competition between electrostatic and hydrodynamic forces. Sorting speeds up to 1200 per second are demonstrated for conductive drops of 160 pl in low viscosity oil.
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Affiliation(s)
- Arjen M Pit
- Physics of Complex Fluids Group, MESA+ Institute, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Riëlle de Ruiter
- Physics of Complex Fluids Group, MESA+ Institute, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Anand Kumar
- Physics of Complex Fluids Group, MESA+ Institute, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Daniel Wijnperlé
- Physics of Complex Fluids Group, MESA+ Institute, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Michèl H G Duits
- Physics of Complex Fluids Group, MESA+ Institute, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids Group, MESA+ Institute, University of Twente , P.O. Box 217, 7500 AE Enschede, The Netherlands
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de Ruiter R, Semprebon C, van Gorcum M, Duits MHG, Brinkmann M, Mugele F. Stability Limits of Capillary Bridges: How Contact Angle Hysteresis Affects Morphology Transitions of Liquid Microstructures. PHYSICAL REVIEW LETTERS 2015; 114:234501. [PMID: 26196804 DOI: 10.1103/physrevlett.114.234501] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Indexed: 05/25/2023]
Abstract
The equilibrium shape of a drop in contact with solid surfaces can undergo continuous or discontinuous transitions upon changes in either drop volume or surface energies. In many instances, such transitions involve the motion of the three-phase contact line and are thus sensitive to contact angle hysteresis. Using a combination of electrowetting-based experiments and numerical calculations, we demonstrate for a generic sphere-plate confinement geometry how contact angle hysteresis affects the mechanical stability of competing axisymmetric and nonaxisymmetric drop conformations and qualitatively changes the character of transitions between them.
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Affiliation(s)
- Riëlle de Ruiter
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Ciro Semprebon
- Dynamics of Complex Fluids, Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
| | - Mathijs van Gorcum
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Michèl H G Duits
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Martin Brinkmann
- Dynamics of Complex Fluids, Max-Planck-Institute for Dynamics and Self-Organization, Am Faßberg 17, 37077 Göttingen, Germany
- Experimental Physics, Saarland University, 66123 Saarbrücken, Germany
| | - Frieder Mugele
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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Cavalli A, Musterd M, Mugele F. Numerical investigation of dynamic effects for sliding drops on wetting defects. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 91:023013. [PMID: 25768603 DOI: 10.1103/physreve.91.023013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Indexed: 06/04/2023]
Abstract
The ability to trap or deflect sliding drops is of great interest in microfluidics, as it has several technological applications, ranging from self-cleaning and fog harvesting surfaces to laboratory-on-a-chip devices. We present a three-dimensional numerical model that describes sliding droplets interacting with wetting defects of variable strength and size. This approach provides relevant insight if compared to simplified analytic models, as it allows us to assess the relevance of the internal degrees of freedom of the droplet. We observe that the deformation of the drop enhances the effective strength and range of the defect, and we quantify this effect by comparison to a point-mass model. We also analyze the role of the steepness and strength of the defect on the drop motion, observing that small, strong defects are more effective at trapping than large, shallow traps of same excess surface energy. Finally, our results show quantitative agreement with previously reported electrowetting experiments, suggesting a universal behavior in droplet trapping that does not depend strongly on the nature of the defect.
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Affiliation(s)
- Andrea Cavalli
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands
| | - Michiel Musterd
- Product and Process Engineering, TNW-PPE/TP, Delft University of Technology, 2628 CN Delft, The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands
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Abstract
Controlling the motion of drops on solid surfaces is crucial in many natural phenomena and technological processes including the collection and removal of rain drops, cleaning technology and heat exchangers. Topographic and chemical heterogeneities on solid surfaces give rise to pinning forces that can capture and steer drops in desired directions. Here we determine general physical conditions required for capturing sliding drops on an inclined plane that is equipped with electrically tunable wetting defects. By mapping the drop dynamics on the one-dimensional motion of a point mass, we demonstrate that the trapping process is controlled by two dimensionless parameters, the trapping strength measured in units of the driving force and the ratio between a viscous and an inertial time scale. Complementary experiments involving superhydrophobic surfaces with wetting defects demonstrate the general applicability of the concept. Moreover, we show that electrically tunable defects can be used to guide sliding drops along actively switchable tracks-with potential applications in microfluidics.
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de Ruiter R, Pit AM, de Oliveira VM, Duits MHG, van den Ende D, Mugele F. Electrostatic potential wells for on-demand drop manipulation in microchannels. LAB ON A CHIP 2014; 14:883-91. [PMID: 24394887 DOI: 10.1039/c3lc51121a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Precise control and manipulation of individual drops are crucial in many lab-on-a-chip applications. We present a novel hybrid concept for channel-based discrete microfluidics with integrated electrowetting functionality by incorporating co-planar electrodes (separated by a narrow gap) in one of the microchannel walls. By combining the high throughput of channel-based microfluidics with the individual drop control achieved using electrical actuation, we acquire the strengths of both worlds. The tunable strength of the electrostatic forces enables a wide range of drop manipulations, such as on-demand trapping and release, guiding, and sorting of drops in the microchannel. In each of these scenarios, the retaining electrostatic force competes with the hydrodynamic drag force. The conditions for trapping can be predicted using a simple model that balances these forces.
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Affiliation(s)
- Riëlle de Ruiter
- Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands.
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Tadmor R. Misconceptions in wetting phenomena. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15474-15475. [PMID: 24256467 DOI: 10.1021/la403578q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In a recent paper ('t Mannetje, D.; Banpurkar, A.; Koppelman, H.; Duits, M. H. G.; van den Ende, D.; Mugele, F. Electrically Tunable Wetting Defects Characterized by a Simple Capillary Force Sensor. Langmuir 2013, 29, 9944-9949), there are a few misconceptions regarding the interpretations of theories emanating from Shanahan and de Gennes in describing centrifugal adhesion balance (CAB) experiments, making their results seemingly contradictory to the theory. These are clarified here. We show that their results, if interpreted correctly, do not contradict the theories mentioned above.
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Affiliation(s)
- Rafael Tadmor
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States
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Mampallil D, Eral HB, Staicu A, Mugele F, van den Ende D. Electrowetting-driven oscillating drops sandwiched between two substrates. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:053015. [PMID: 24329359 DOI: 10.1103/physreve.88.053015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Indexed: 06/03/2023]
Abstract
Drops sandwiched between two substrates are often found in lab-on-chip devices based on digital microfluidics. We excite azimuthal oscillations of such drops by periodically modulating the contact line via ac electrowetting. By tuning the frequency of the applied voltage, several shape modes can be selected one by one. The frequency of the oscillations is half the frequency of the contact angle modulation by electrowetting, indicating a parametric excitation. The drop response to sinusoidal driving deviates substantially from sinusoidal behavior in a "stop and go" fashion. Although our simple theoretical model describes the observed behavior qualitatively, the resonances appear at lower frequencies than expected. Moreover, the oscillations produce a nonperiodic fluid transport within the drop with a typical velocity of 1 mm/s. In digital microfluidic devices, where the typical drop size is less than 1 mm, this flow can result in very fast mixing on the spot.
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Affiliation(s)
- Dileep Mampallil
- Physics of Complex Fluids, MESA+ Institute, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - H Burak Eral
- Physics of Complex Fluids, MESA+ Institute, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Adrian Staicu
- Physics of Complex Fluids, MESA+ Institute, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids, MESA+ Institute, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
| | - Dirk van den Ende
- Physics of Complex Fluids, MESA+ Institute, Department of Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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