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Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State

The difficulty of measuring very large contact angles (>150 degrees) has become more relevant with the increased popularity of super-repellent surfaces. Measurement is more difficult for dynamic contact angles, for which theoretical profiles do not fit well, and small capillary length liquids, wh...

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Autores principales: Liu, Tingyi “Leo”, Kim, Chang-Jin “CJ”
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5428877/
https://www.ncbi.nlm.nih.gov/pubmed/28389672
http://dx.doi.org/10.1038/s41598-017-00607-9
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author Liu, Tingyi “Leo”
Kim, Chang-Jin “CJ”
author_facet Liu, Tingyi “Leo”
Kim, Chang-Jin “CJ”
author_sort Liu, Tingyi “Leo”
collection PubMed
description The difficulty of measuring very large contact angles (>150 degrees) has become more relevant with the increased popularity of super-repellent surfaces. Measurement is more difficult for dynamic contact angles, for which theoretical profiles do not fit well, and small capillary length liquids, whose sessile droplets sag by gravity. Here, we expand the issue to the limit by investigating dynamic contact angles of liquids with an extremely small capillary length (<1.0 mm), empowered by the superomniphobic surface that can super-repel even fluorinated solvents, which highly wet all materials. Numerically simulating and experimentally testing 13 different liquids on the superomniphobic surface, we discover their dynamic contact angles can be measured with a consistent accuracy despite their vastly different capillary lengths if one keeps the lens magnification inversely proportional to the capillary length. Verifying the droplet equator height is a key parameter, we propose a new Bond number defined by the equator height and optical resolution to represent the measurement accuracy of large contact angles. Despite negligible improvement for most liquids today, the proposed approach teaches how to measure very large contact angles with consistent accuracy when any of the liquids in consideration has a capillary length below 1.0 mm.
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spelling pubmed-54288772017-05-15 Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State Liu, Tingyi “Leo” Kim, Chang-Jin “CJ” Sci Rep Article The difficulty of measuring very large contact angles (>150 degrees) has become more relevant with the increased popularity of super-repellent surfaces. Measurement is more difficult for dynamic contact angles, for which theoretical profiles do not fit well, and small capillary length liquids, whose sessile droplets sag by gravity. Here, we expand the issue to the limit by investigating dynamic contact angles of liquids with an extremely small capillary length (<1.0 mm), empowered by the superomniphobic surface that can super-repel even fluorinated solvents, which highly wet all materials. Numerically simulating and experimentally testing 13 different liquids on the superomniphobic surface, we discover their dynamic contact angles can be measured with a consistent accuracy despite their vastly different capillary lengths if one keeps the lens magnification inversely proportional to the capillary length. Verifying the droplet equator height is a key parameter, we propose a new Bond number defined by the equator height and optical resolution to represent the measurement accuracy of large contact angles. Despite negligible improvement for most liquids today, the proposed approach teaches how to measure very large contact angles with consistent accuracy when any of the liquids in consideration has a capillary length below 1.0 mm. Nature Publishing Group UK 2017-04-07 /pmc/articles/PMC5428877/ /pubmed/28389672 http://dx.doi.org/10.1038/s41598-017-00607-9 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Liu, Tingyi “Leo”
Kim, Chang-Jin “CJ”
Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State
title Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State
title_full Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State
title_fullStr Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State
title_full_unstemmed Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State
title_short Contact Angle Measurement of Small Capillary Length Liquid in Super-repelled State
title_sort contact angle measurement of small capillary length liquid in super-repelled state
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5428877/
https://www.ncbi.nlm.nih.gov/pubmed/28389672
http://dx.doi.org/10.1038/s41598-017-00607-9
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