Physicists make square droplets and liquid grids

Credit: Aalto University

When the two substances come together, they eventually settle into a steady state called thermodynamic equilibrium. Examples include oil that floats on water and milk that mixes evenly with coffee. Researchers at Aalto University in Finland wanted to confuse this kind of state and see what was happening and whether they could control the outcome.

“Equilibrium tends to be very boring,” the research group said. Science Advances September 15th. “It’s fascinating to take the system out of equilibrium and see if it can control or help non-equilibrium structures. Biological life itself is a truly complex and well-behaved molecule that is out of bundle. Here is an example. Thermodynamic equilibrium.. “

In their work, the team used a combination of oils with different permittivity and conductivity.Then they put the liquid electric field..

“When you apply an electric field to the mixture, charge Accumulates at the interface between oils.this Charge density Shears the interface from thermodynamic equilibrium to interesting formations, “explains Dr. Nikoskiria Copros, one of the authors of the treatise. Not only was it destroyed by the electric field, but the liquid was thin and trapped in an almost two-dimensional sheet. .. This combination caused the oil to reshape into a variety of completely unexpected droplets and patterns.

The experimental droplets can be squares or hexagons with straight sides. This is almost impossible in nature, where small bubbles and droplets tend to form spheres. The two liquids can also be formed in an interconnected grid. Occurs regularly on solid materials, but with an unprecedented grid pattern. liquid mixture. The liquid can also be induced to form the shape of a torus, a donut. This is because, unlike in nature, it retains its shape steadily while the field is applied, as the liquid tends to collapse and fill the central hole. The liquid can also form filaments that rotate and rotate around an axis.

“All of these strange shapes are caused and maintained by the fact that the movement of charges that accumulate at the interface prevents them from returning to equilibrium,” said Geet Raju, the first author of the treatise.

One of the exciting consequences of this task is the ability to create a controlled, well-sized temporary structure that can be switched on and off by voltage. This area is of interest to further research by researchers to create voltage controlled optics. .. Another potential outcome is to create an interacting population of rotating microfilaments and microdroplets that mimics the dynamics and collective behavior of microorganisms such as bacteria and microalgae that propel using completely different mechanisms. Ability.

This study was conducted in the Department of Applied Physics of the Active Matter Research Group, led by Professor Timonen.Treatise “Non-diversityequilibrium The emergence of patterns and activities in confined electrohydrodynamically driven liquids “is open access. Science Advances..

Effective temperature connects balanced and non-equilibrium systems

For more information:
The variety of non-equilibrium patterns and the emergence of activity in confined electrohydrodynamically driven liquids, Science Advances (2021). DOI: 10.1126 / sciadv.abh1642

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Aalto University

Quote: Physicists, obtained from on September 15, 2021 Square Droplets and Liquid Lattice (2021) September 15, 2014)

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Physicists make square droplets and liquid grids

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