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Superconfinement tailors fluid flow at microscales.

Setu SA, Dullens RP, Hernández-Machado A, Pagonabarraga I, Aarts DG, Ledesma-Aguilar R - Nat Commun (2015)

Bottom Line: Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices.Henceforth, we present a theory that quantifies our experiments in terms of the relevant interfacial length scale, which in our system is the intrinsic contact-line slip length.Our findings show that length-scale overlap can be used as a new fluid-control mechanism in strongly confined systems.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK [2] Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Johor 81310, Malaysia.

ABSTRACT
Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices. Here we report measurements of advancing fluid fronts in such a regime, which we dub superconfinement. We find that the strong coupling between contact-line friction and geometric confinement gives rise to a new stability regime where the maximum speed for a stable moving front exhibits a distinctive response to changes in the bounding geometry. Unstable fronts develop into drop-emitting jets controlled by thermal fluctuations. Numerical simulations reveal that the dynamics in superconfined systems is dominated by interfacial forces. Henceforth, we present a theory that quantifies our experiments in terms of the relevant interfacial length scale, which in our system is the intrinsic contact-line slip length. Our findings show that length-scale overlap can be used as a new fluid-control mechanism in strongly confined systems.

No MeSH data available.


Related in: MedlinePlus

Tip-splitting and concurrent drop emission.At high values of the capillary ratio, , the front splits into two fingers that subsequently destabilize and emit drops periodically. Scale bar, 100 μm.
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f6: Tip-splitting and concurrent drop emission.At high values of the capillary ratio, , the front splits into two fingers that subsequently destabilize and emit drops periodically. Scale bar, 100 μm.

Mentions: The combination of low surface tension and strong confinement in our set-up can be further exploited to induce the formation of complex structures; by quickly forcing the interface into our microchannels, it is possible to trigger the formation of pairs of fingers that subsequently emit drops concurrently (Fig. 6 and Supplementary Movie 3). These experiments indicate the feasibility of manipulating fluids through the combination of low surface tension and superconfinement, and open the possibility of controlling the stability and synchronization of the emerging structures.


Superconfinement tailors fluid flow at microscales.

Setu SA, Dullens RP, Hernández-Machado A, Pagonabarraga I, Aarts DG, Ledesma-Aguilar R - Nat Commun (2015)

Tip-splitting and concurrent drop emission.At high values of the capillary ratio, , the front splits into two fingers that subsequently destabilize and emit drops periodically. Scale bar, 100 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4490407&req=5

f6: Tip-splitting and concurrent drop emission.At high values of the capillary ratio, , the front splits into two fingers that subsequently destabilize and emit drops periodically. Scale bar, 100 μm.
Mentions: The combination of low surface tension and strong confinement in our set-up can be further exploited to induce the formation of complex structures; by quickly forcing the interface into our microchannels, it is possible to trigger the formation of pairs of fingers that subsequently emit drops concurrently (Fig. 6 and Supplementary Movie 3). These experiments indicate the feasibility of manipulating fluids through the combination of low surface tension and superconfinement, and open the possibility of controlling the stability and synchronization of the emerging structures.

Bottom Line: Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices.Henceforth, we present a theory that quantifies our experiments in terms of the relevant interfacial length scale, which in our system is the intrinsic contact-line slip length.Our findings show that length-scale overlap can be used as a new fluid-control mechanism in strongly confined systems.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK [2] Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, Johor Bahru, Johor 81310, Malaysia.

ABSTRACT
Understanding fluid dynamics under extreme confinement, where device and intrinsic fluid length scales become comparable, is essential to successfully develop the coming generations of fluidic devices. Here we report measurements of advancing fluid fronts in such a regime, which we dub superconfinement. We find that the strong coupling between contact-line friction and geometric confinement gives rise to a new stability regime where the maximum speed for a stable moving front exhibits a distinctive response to changes in the bounding geometry. Unstable fronts develop into drop-emitting jets controlled by thermal fluctuations. Numerical simulations reveal that the dynamics in superconfined systems is dominated by interfacial forces. Henceforth, we present a theory that quantifies our experiments in terms of the relevant interfacial length scale, which in our system is the intrinsic contact-line slip length. Our findings show that length-scale overlap can be used as a new fluid-control mechanism in strongly confined systems.

No MeSH data available.


Related in: MedlinePlus