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Microfluidic control over topological states in channel-confined nematic flows
Compared to isotropic liquids, orientational order of nematic liquid crystals makes their rheological properties more involved, and thus requires fine control of the flow parameters to govern the orientational patterns. In microfluidic channels with perpendicular surface alignment, nematics disconti...
Autores principales: | , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Nature Publishing Group UK
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6940393/ https://www.ncbi.nlm.nih.gov/pubmed/31896755 http://dx.doi.org/10.1038/s41467-019-13789-9 |
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author | Čopar, Simon Kos, Žiga Emeršič, Tadej Tkalec, Uroš |
author_facet | Čopar, Simon Kos, Žiga Emeršič, Tadej Tkalec, Uroš |
author_sort | Čopar, Simon |
collection | PubMed |
description | Compared to isotropic liquids, orientational order of nematic liquid crystals makes their rheological properties more involved, and thus requires fine control of the flow parameters to govern the orientational patterns. In microfluidic channels with perpendicular surface alignment, nematics discontinuously transition from perpendicular structure at low flow rates to flow-aligned structure at high flow rates. Here we show how precise tuning of the driving pressure can be used to stabilize and manipulate a previously unresearched topologically protected chiral intermediate state which arises before the homeotropic to flow-aligned transition. We characterize the mechanisms underlying the transition and construct a phenomenological model to describe the critical behaviour and the phase diagram of the observed chiral flow state, and evaluate the effect of a forced symmetry breaking by introduction of a chiral dopant. Finally, we induce transitions on demand through channel geometry, application of laser tweezers, and careful control of the flow rate. |
format | Online Article Text |
id | pubmed-6940393 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Nature Publishing Group UK |
record_format | MEDLINE/PubMed |
spelling | pubmed-69403932020-01-06 Microfluidic control over topological states in channel-confined nematic flows Čopar, Simon Kos, Žiga Emeršič, Tadej Tkalec, Uroš Nat Commun Article Compared to isotropic liquids, orientational order of nematic liquid crystals makes their rheological properties more involved, and thus requires fine control of the flow parameters to govern the orientational patterns. In microfluidic channels with perpendicular surface alignment, nematics discontinuously transition from perpendicular structure at low flow rates to flow-aligned structure at high flow rates. Here we show how precise tuning of the driving pressure can be used to stabilize and manipulate a previously unresearched topologically protected chiral intermediate state which arises before the homeotropic to flow-aligned transition. We characterize the mechanisms underlying the transition and construct a phenomenological model to describe the critical behaviour and the phase diagram of the observed chiral flow state, and evaluate the effect of a forced symmetry breaking by introduction of a chiral dopant. Finally, we induce transitions on demand through channel geometry, application of laser tweezers, and careful control of the flow rate. Nature Publishing Group UK 2020-01-02 /pmc/articles/PMC6940393/ /pubmed/31896755 http://dx.doi.org/10.1038/s41467-019-13789-9 Text en © The Author(s) 2020 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 Čopar, Simon Kos, Žiga Emeršič, Tadej Tkalec, Uroš Microfluidic control over topological states in channel-confined nematic flows |
title | Microfluidic control over topological states in channel-confined nematic flows |
title_full | Microfluidic control over topological states in channel-confined nematic flows |
title_fullStr | Microfluidic control over topological states in channel-confined nematic flows |
title_full_unstemmed | Microfluidic control over topological states in channel-confined nematic flows |
title_short | Microfluidic control over topological states in channel-confined nematic flows |
title_sort | microfluidic control over topological states in channel-confined nematic flows |
topic | Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6940393/ https://www.ncbi.nlm.nih.gov/pubmed/31896755 http://dx.doi.org/10.1038/s41467-019-13789-9 |
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