New structures self-assemble in synchronized dance (w/ video)

Nov 21, 2012
Researchers from the University of Illinois and Northwestern University demonstrated tiny spheres that synchronize their movements as they self-assemble into a spinning microtube. Back, L-R: Northwestern University professor Erik Luijten, U. of I. professor Steve Granick. Front: Grad student Jing Yan, research scientist Sung Chul Bae. Credit: L. Brian Stauffer

With self-assembly guiding the steps and synchronization providing the rhythm, a new class of materials forms dynamic, moving structures in an intricate dance.

Researchers from the University of Illinois and Northwestern University have demonstrated that synchronize their movements as they self-assemble into a spinning microtube. Such in-motion structures, a blending of mathematics and materials science, could open a new class of technologies with applications in medicine, chemistry and engineering. The results will be published in the Nov. 22 edition of the journal Nature.

"The world's concept of self-assembly has been to think of static structures – something you would see in a still image," said Steve Granick, Founder Professor of Engineering at the U. of I. and a co-leader of the study. "We want shape-shifting structures. Structures where a photograph doesn't tell you what matters. It's like the difference between a photograph and a movie."

The researchers used called Janus spheres, named after the Roman god with two faces, which Granick's group developed and previously demonstrated for self-assembly of static structures. In this study, one half of each sphere is coated with a magnetic metal. When dispersed in solution and exposed to a rotating , each sphere spins in a gyroscopic motion. They spin at the same frequency but all face a different direction, like a group of dancers in a ballroom dancing to the same beat but performing their own steps.

As two particles approach one another, they synchronize their and begin spinning around a shared center, facing opposite directions, similar to the way a couple dancing together falls in step looking at one another.

"They are both magnetized, which causes them to attract each other, but because they're moving, they have to move in sync," said Erik Luijten, a professor of and of applied mathematics at Northwestern University who co-led the research with Granick.

Soon, the pairs and clusters of dancing spheres assemble themselves into a microtube – a long, hollow . The entire tube spins, even as each individual sphere continues its motion as well, like dancers in a line dance completing their individual steps as the line moves.

This video is not supported by your browser at this time.

"It's spontaneous. We don't force it to form," said U. of I. graduate student Jing Yan, the first author of the paper. "We saw that during the self-assembly process, the also happens. If you look at the spheres, every one is doing a different thing. Only when they come in close contact will they do something cooperatively. The two concepts are intricately related in this system."

Now that the researchers have detailed the delicate choreography of synchronization and self-assembly, they hope to explore applications for this new class of moving structures. One potential application of a dynamic, self-assembled microtube is to transport and release cargo. A particle or collection of molecules could be encapsulated in the tube and transported to a different location. Then, the tube can be disintegrated, releasing the cargo at a target point.

"We're looking for the new applications that people haven't dreamt up yet because they didn't have the capability," said Granick, a professor of and engineering.

Next, the researchers are working to further understand the properties governing synchronized self-assembly and ways to guide it for functionality, such as manipulating the structures with an electrical or magnetic field. They also plan to explore directing the Janus spheres to synchronized self-assembly of other shapes and structures, allowing even more applications.

"Traditionally in self-assembly, you make a specific building block that will organize into a specific structure," Luijten said. "If you want a different structure you have to make a different building block. Here now, with one building block, we can control the structure by exploiting the synchronization effect."

Explore further: Theorists find a new way to improve efficiency of solar cells by overcoming exciton 'traps'

Related Stories

New Self-Assemble Building Blocks for Nanotechnology

Aug 19, 2004

University of Michigan researchers have discovered a way to self-assemble nanoparticles into wires, sheets, shells and other unusual structures using sticky patches that make the particles group themselves together in progra ...

Janus particles offer new physics, new technology

Mar 13, 2006

In Roman mythology, Janus was the god of change and transition, often portrayed with two faces gazing in opposite directions. At the University of Illinois at Urbana-Champaign, Janus particles are providing ...

Long polymer chains dance the conga

Mar 16, 2010

Understanding the steps to the intricate dance inside a cell is essential to one day choreographing the show. By studying the molecules that give a cell its structure, University of Illinois researchers are ...

Creating nanostructures from the bottom up

Apr 24, 2012

Microscopic particles are being coaxed by Duke University engineers to assemble themselves into larger crystalline structures by the use of varying concentrations of microscopic particles and magnetic fields.

Recommended for you

New complex oxides could advance memory devices

Sep 17, 2014

The quest for the ultimate memory device for computing may have just taken an encouraging step forward. Researchers at The City College of New York led by chemist Stephen O'Brien have discovered new complex ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Jeddy_Mctedder
2.3 / 5 (6) Nov 21, 2012
video not working
Macksb
1 / 5 (2) Nov 21, 2012
Periodic oscillators have a tendency to synchronize their oscillations in certain precise ways. This experiment involves a system of identical periodic oscillators. See law of coupled oscillators described by Art Winfree circa 1967. Also Kumamoto, Strogatz, Mirollo. See Scientific American Dec 1993. "Coupled oscillators and Biological Synchronization". Copy online at. Math.oregonstate.edu