How scientists inverted the Cheerios effect

June 13, 2016, Queen Mary, University of London

Liquid drops on soft solid surfaces interact by an 'inverted Cheerios effect', which can be tweaked so that the droplets move towards or away from each other, according to an international group of scientists publishing in the journal Proceedings of the National Academy of Sciences.

The phenomenon of the famous breakfast cereal clumping together when floating in a milk bowl is known as the Cheerios effect. The 'inverted Cheerios effect', identified in this paper for the first time, describes a similar scenario but with the roles of liquid and solid being interchanged: liquid droplets interact when resting on a solid—but soft—surface.

In recent years, the classical Cheerios effect has inspired a new set of manufacturing technologies for advanced materials and helped physicists understanding the gravitational collapse of galaxies. Similarly, the newly discovered 'inverted Cheerios effect' may open up new opportunities in engineering and the life sciences.

"Tuning the movement of liquid droplets could have implications for the performance of engineering technologies which rely on drops of water and other liquids," said co-author Dr Lorenzo Botto from Queen Mary University of London's School of Engineering and Materials Science (London, UK).

"For example, the physical phenomena we have highlighted in this paper suggest ways to design surfaces that prevent fogging or control heat transfer; for instance to create car windows that are always transparent despite high humidity or surfaces that improve heat management in conditioners or boilers. By making surfaces softer or harder, and changing the thickness of the soft layer, we will be able to control how the drops coalesce and spread on the substrate."

The international team of scientists suggest the interactions of the liquid particles can be tuned to repel each other or move towards each other by changing the thickness and softness of the substrate.

Co-author Stefan Karpitschka, who recently moved from University of Twente (Enschede, The Netherlands) to Stanford University (California, USA), said: "The droplets deform the surface on which they live, and due to this deformation, they interact; somewhat reminiscent of general relativity, from which we know that galaxies or black holes interact by deforming space around them.

"What is remarkable about our case though is the fact that the direction of the interaction can be tuned by the medium, without modifying the particles themselves."

Dr Botto added: "While the science is quite young, there are exciting implications of our work not just limited to engineering. For example, quantifying the forces at play when drops sit on a soft layer will also help us understand how cells interact with each other and with the soft tissues on which they live."

Explore further: Researchers identify movement of droplets on soft surfaces

More information: Liquid drops attract or repel by the inverted cheerios effect, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1601411113

Related Stories

Researchers identify movement of droplets on soft surfaces

August 5, 2015

Researchers from the University of Twente have succeeded in clearly identifying why droplets on soft, squishy surfaces react differently than on hard surfaces. A water droplet, for example, moves very differently over jelly ...

Water droplets prefer the soft touch

June 25, 2013

(Phys.org) —Researchers have found a way to drive water droplets along a flat surface without applying heat, chemicals, electricity, or other forces: All that's required is varying the stiffness of the surface in the desired ...

Engineers use liquid drops to make solids stiffer

December 16, 2014

(Phys.org)—Engineers at Yale University have discovered that the stiffness of liquid drops embedded in solids has something in common with Goldilocks: While large drops of liquids are softer than the solid that surrounds ...

Recommended for you

Some black holes erase your past

February 21, 2018

In the real world, your past uniquely determines your future. If a physicist knows how the universe starts out, she can calculate its future for all time and all space.

Reaching new heights in laser-accelerated ion energy

February 20, 2018

A laser-driven ion acceleration scheme, developed in research led at the University of Strathclyde, could lead to compact ion sources for established and innovative applications in science, medicine and industry.

MEMS chips get metatlenses

February 20, 2018

Lens technologies have advanced across all scales, from digital cameras and high bandwidth in fiber optics to the LIGO lab instruments. Now, a new lens technology that could be produced using standard computer-chip technology ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.