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).

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!