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Dancing liquid crystals


Liquid crystal droplets in soapy water produce dazzling patterns.


Iridescent, fingerprint-like patterns appear on the surfaces of these liquid crystal droplets.
Iridescent, fingerprint-like patterns appear on the surfaces of these liquid crystal droplets.
Lisa Tran

These entrancing patterns are created by soapy molecules attracted to the surface of liquid crystal droplets in water.

Liquid crystals, fluids with aligned phases of constituent molecules, are used in everything from computer and television displays to mood rings. Since liquid crystals are made of rod-like molecules, they have special optical properties, such as changing color as they interact with electrical signals or light.

Surfactants like soap are attracted to the oil-like liquid crystals, changing the arrangement of the liquid crystal molecules and creating the striking patterns. Adding more soap to the solution changed the patterns (see animation below), while adding water reversed the changes.

Dancing patterns in liquid crystal droplets.
Dancing patterns in liquid crystal droplets.
Lisa Tran

Researcher Lisa Tran, a graduate student at the University of Pennsylvania in the US, also noted that – while the detailed patterns can only be seen under a microscope – changing the concentration of soap produced changes in the solution that were visible to the naked eye. This means the technique has potential for use in testing liquids for poisons or other contaminants.

A paper on the research by Tran and collaborators is published in Physical Review X.

Curated content from the editorial staff at Cosmos Magazine.
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