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Banner image: Clusters of solitons form in a liquid crystal. (Credit: Smalyukh lab)听

Take a dive into what may be the world鈥檚 smallest coral reef. Scientists at CU听Boulder are using a type of material called liquid crystals to create incredibly small, swirling schools of 鈥渇ish,鈥� according to a study .听

The fish in this case aren鈥檛 actually aquatic animals. They鈥檙e minute disruptions in the orientations of the molecules that make up solutions of liquid crystals, said Hayley Sohn, lead author of the new study.

But under the microscope, these molecular deformations鈥�10 of which could fill the width of a human hair鈥攃ertainly look alive. These pseudo-particles can twirl together as a group, shift their motion on a dime and even flow around obstacles when exposed to different electric currents.听

鈥淏y tuning that voltage, I can have them move in different directions and make them form a nice cluster where they鈥檙e all stuck together. They can branch out into a chain and then come back together,鈥� said Sohn, a graduate student in the Materials Science and Engineering Program at CU Boulder. 鈥淚t鈥檚 very fun to play with.鈥�

The team hopes that its tiny reefs could one day become part of new smartphone screens or even video games.

Study co-author Ivan Smalyukh, a professor in the Department of Physics, explained that liquid crystals are a major component of modern display technologies, from computer tablets to high-definition TVs.听

鈥淥ur work is very compatible with this multi-billion dollar display industry,鈥� Smalyukh said. 鈥淚t could add to the new spectrum of ways that humans and computers interface.鈥�

Stadium crowds

His group鈥檚 discovery, however, came about almost by accident.

Sohn had been experimenting with new ways to create large groups of those deformations within liquid crystal solutions, a phenomenon that physicists call 鈥渟olitons.鈥澨�

The team鈥檚 liquid crystal solutions, she said, are made up of quintillions of rod-shaped molecules鈥攖hink of them like the crowds in CU Boulder鈥檚 Folsom Field, which she can see from the window of her office. Normally, those football fans don鈥檛 get in each other鈥檚 way, but if you prepare a liquid crystal solution in a precise manner, they will start to squeeze together.听

鈥淲e can create conditions that make the liquid crystal frustrated,鈥� Smalyukh said.

To offset that frustration, small pockets will form in the liquid crystal solution in which the molecules inside bend and twist in unusual ways. These solitons don鈥檛 actually move in the traditional sense. Instead, their deformed structure passes throughout the solution, a bit like another common occurrence at sports arenas.听

鈥淚t鈥檚 like if you鈥檙e at the stadium, and the crowd is doing the wave,鈥� Sohn said. 鈥淭he wave only moves because the people are changing how they point their arms.鈥�

One day in the lab, Sohn prepared a microscope slide with a group of several solitons, then took a break. When she came back, her creations were no longer on the view screen.

鈥淚 thought, 鈥極h, no. I have to do this experiment all over again,鈥欌�� Sohn said. 鈥淭hen I looked at the video playback and saw this schooling behavior. I was just amazed. It wasn鈥檛 a failure.鈥�

Emergent phenomena

And, Sohn added, the solitons didn鈥檛 move like inanimate objects. She explained that, under the right conditions, these molecular fish can interact with each other. That means that they can bump into each other and influence each other鈥檚 trajectories, creating patterns that are almost impossible to foresee ahead of time鈥攈ence the comparison to thousands of fish linking up their motions.听听

It's an area of research that, Sohn said, fits with her own hobbies.

鈥淥ne of the best parts of this research, for me, is that I can draw inspiration from and make connections to nature, such as the schools of fish I鈥檝e seen SCUBA diving,鈥� she said. 鈥淣ext time I go diving, I鈥檒l just call it research.鈥� 听

Smalyukh, in particular, is excited about how unpredictable the schools of solitons can be. He said that such behavior could lead to different kind of interactive display technology, one in which the images that you see on a screen aren鈥檛 necessarily pre-programmed but appear and shift according to the emergent motions of the soliton schools.

鈥淚magine a new type of computer game where you cannot predict what will happen next after you push on the screen,鈥� Smalyukh said. 鈥淚t wouldn鈥檛 be programmed but shaped by emergent phenomena.鈥�