Keith Haring at the colloidal scale and dynamic capillarity

Art and science have come together in our lab as we observed this pattern of microparticles sitting on the surface of a bubble. The observed microstructure resembles a human figure in American mural artist Keith Haring’s distinctive style.

The microstructures formed by colloids at fluid interfaces are usually due to electrostatics and capillarity. This unique microstructure was obtained by deforming a bubble decorated with colloidal particles with ultrasonic waves, resulting in complex dynamic interactions between the particles. The science behind making chains of particles by dynamic capillarity is explained in our paper Dynamic capillary assembly of colloids at interfaces with 10,000g accelerations, published today in Nature Communications.

The first author of the paper, Axel Huerre, led this work as a postdoc in our group in 2016-2018. He is now a postdoc at LadHyx, Ecole Polytechnique in Paris, where he studies the coupling between hydrodynamics and phase changes in capillary problems. The interaction model presented in the paper was developed by co-author Marco De Corato, also a postdoc in our group.

For the past 3 years we have been investigating extreme deformation of particle-laden fluid interfaces in the framework of ERC-funded project ExtreFlow. Marco has also developed a theoretical model for the effects of the dynamic deformation of the interface by oscillating particles, described in his paper Capillary interactions between dynamically forced particles adsorbed at a planar interface and on a bubble, which was published (Open Access) earlier this year in the Journal of Fluid Mechanics.

We will present both papers at the upcoming 12th European Fluid Mechanics Conference in Vienna (9-13 September 2018). If you’re interested, come along to our talks on Tuesday, 11 September, in the Mini Symposium “Particles at Interfaces”. See you then!

Image: 2-µm fluorescent microparticles at 30% surface coverage on an air bubble of radius 86 µm suspended in water. From: A. Huerre, M. De Corato, V. Garbin, Dynamic capillary assembly of colloids at interfaces with 10,000g accelerations, Nature Communications 9, 3620 (2018).

London Light launch event hosts our dancing soap bubbles

We are bringing dancing soap bubbles live again! We are invited on 9 May 2018 to the London Light Launch Event to show how sound and light can interact in a very graceful way using a bottle, a speaker and some soapy water.

The London Light institute brings together scientists and industries in London who work on emerging photonic technologies. The launch event will take place at King’s College London and coincides with the first International Day of Light. It is open to all. You can  register for free!

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Photos from Imperial Festival 2018

 

 

 

Dancing on sound waves at Imperial Festival 2018

We are getting ready with two exciting demos for Imperial Festival 2018 on 28-29 April. The festival invites the wide community to experience Imperial’s research in science, engineering, health and business up close.

From acoustic levitation to sound beam tweezers, ultrasonic shrimp to light emitting bubbles, some effects of sound can appear in ways that are often not well understood. In our research, we analyse the complex interaction of sound waves with solids, liquids and bubbles to characterize their rich and complex behaviour and probe their fundamental properties.

We are bringing to the Festival two experiments that will guide the audience to understand some unusual ways in which sound waves can interact with matter.

We have built a sonic levitator to provide a demonstration for the very tiny forces that acoustic waves can exert on sound-reflecting objects, ultimately buiding up to levitate solid bodies in air!

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Bring your own tiny object. We will try to levitate it!

In the second experiment, we invite you to experience a beautiful way to visualize sound, by observing a soap film trapped in a bottle’s neck. Music emitted from a speaker forces the bottle to resonate for a particular set of musical frequencies. A fascinating consequence is that the colour bands that appear on a soap film… cannot help it! They start to move and dance in synch with the music in a very graceful way. The sound/light interaction experiment is triggered by complex hydrodynamic effects taking place within the bottle including acoustic vibrations, capillary waves and 2D turbulence patterns.

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What will your favourite song look like on a soap film?

The images in this article are from previous events we attended – We Are Robots and Hackoustic.

We look forward to seeing you this weekend!

Annual European Rheology Conference 2018

We are getting ready for AERC 2018 in Sorrento (Italy) on 17-20 April 2018. Our group has two oral presentations and one poster presentation on the ExtreFlow project. Axel will give a talk on “Transient string formation in colloid monolayers at fluid interfaces under ultrafast deformation” (preprint available on arXiv). Marco will present his newest results on “Acoustically enhanced bubble removal from yield stress fluids”. Saikat’s poster is on “Rheology of complex interfaces under extreme deformation”. See you in Sorrento!