Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Sophisticated Structures Assembled with Magnets

Uniform clusters of micron-scaled particles assembled by magnetism | Benjamin Yellen lab, Pratt School of Engineering
Uniform clusters of micron-scaled particles assembled by magnetism | Benjamin Yellen lab, Pratt School of Engineering

Abstract:
Technique holds promise for mass-produced nanoparticles

Sophisticated Structures Assembled with Magnets

Durham, NC | Posted on March 24th, 2009

What do Saturn and flowers have in common?

As shapes, both possess certain symmetries that are easily recognizable in the natural world. Now, at an extremely small level, researchers from Duke University and the University of Massachusetts have created a unique set of conditions in which tiny particles within a solution will consistently assemble themselves into these and other complex shapes.

By manipulating the magnetization of a liquid solution, the researchers have for the first time coaxed magnetic and non-magnetic materials to form intricate nano-structures. The resulting structures can be "fixed," meaning they can be permanently linked together. This raises the possibility of using these structures as basic building blocks for such diverse applications as advanced optics, cloaking devices, data storage and bioengineering.

Changing the levels of magnetization of the fluid controls how the particles are attracted to or repelled by each other. By appropriately tuning these interactions, the magnetic and non-magnetic particles form around each other much like a snowflake forms around a microscopic dust particle.

"We have demonstrated that subtle changes in the magnetization of a fluid can create an environment where a mixture of different particles will self-assemble into complex superstructures," said Randall Erb, fourth-year graduate student. He performed these experiments in conjunction with another graduate student Hui Son, in the laboratory of Benjamin Yellen, assistant professor of mechanical engineering and materials science and lead member of the research team.

The results of the Duke experiments appear in Feb. 19 issue of the journal Nature.

The nano-structures are formed inside a liquid known as a ferrofluid, which is a solution consisting of suspensions of nanoparticles composed of iron-containing compounds. One of the unique properties of these fluids is that they become highly magnetized in the presence of external magnetic fields. The unique ferrofluids used in these experiments were developed with colleagues Bappaditya Samanta and Vincent Rotello at the University of Massachusetts.

"The key to the assembly of these nano-structures is to fine-tune the interactions between positively and negatively magnetized particles," Erb said. "This is achieved through varying the concentration of ferrofluid particles in the solution. The Saturn and flower shapes are just the first published examples of a range of potential structures that can be formed using this technique."

According to Yellen, researchers have long been able to create tiny structures made up of a single particle type, but the demonstration of sophisticated structures assembling in solutions containing multiple types of particles has never before been achieved. The complexity of these nano-structures determines how they can ultimately be used.

"It appears that a rich variety of different particle structures are possible by changing the size, type and or degree of magnetism of the particles," Yellen said.

Yellen foresees the use of these nano-structures in advanced optical devices, such as sensors, where different nano-structures could be designed to possess custom-made optical properties. Yellen also envisions that rings composed of metal particles could be used for antenna designs, and perhaps as one of the key components in the construction of materials that display artificial "optical magnetism" and negative magnetic permeability.

In the Duke experiments, the nano-structures were created by applying a uniform magnetic field to a liquid containing various types of magnetic and non-magnetic colloidal particles contained between transparent glass slides to enable real-time microscopic observations of the assembly process. Because of the unique nature of this "bulk" assembly technique, Yellen believes that the process could easily be scaled up to create large quantities of custom-designed nano-structures in high-volume reaction vessels. However, the trick is to also be able to glue the structures together, because they will fall apart when the external field is turned off, he said.

"The magnetic forces assembling these particles are reversible," Yellen said. "We were able to lock these nano-structures in their intended shapes both by using chemical glues and by simple heating."

The Duke team plans to test different combinations of particles and ferrofluids developed by the University of Massachusetts team to create new types of nano-structures. They also want to try to make even smaller nano-structures to find the limitations of the assembly process, and study the interesting optical properties which are expected from these structures.

"While we have shown that we can get small magnetic particles to form complex and beautiful structures, we believe that based on theory and the results of preliminary experiments, we should be able manipulate even smaller particles by using other magnetic particles and ferrofluids," Yellen said.

The research was supported by the National Science Foundation.

(visit their website for a video http://news.duke.edu/2009/02/saturnflower.html)

####

Contacts:
Duke News and Communications
615 Chapel Drive, Box 90563
Durham, NC 27708-0563
T: (919) 684-2823

Copyright © Duke University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Halas wins American Physical Society's Lilienfeld Prize: Rice University nanoscientist honored for pioneering research in plasmonics October 23rd, 2017

GTC Shanghai Highlights GF’s Momentum in China: Company shares details of technology roadmap and customer adoption in the world’s fastest-growing market for semiconductors October 23rd, 2017

Nanobiotix completes patient inclusion for Phase II/III trial of NBTXR3 in soft tissue sarcoma October 23rd, 2017

Arrowhead Pharmaceuticals Reports Inducement Grants under NASDAQ Marketplace Rule 5635(c)(4) October 23rd, 2017

Possible Futures

GTC Shanghai Highlights GF’s Momentum in China: Company shares details of technology roadmap and customer adoption in the world’s fastest-growing market for semiconductors October 23rd, 2017

Researchers bring optical communication onto silicon chips: Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers October 23rd, 2017

Nanotube fiber antennas as capable as copper: Rice University researchers show their flexible fibers work well but weigh much less October 23rd, 2017

Novel 'converter' heralds breakthrough in ultra-fast data processing at nanoscale: Invention bagged four patents and could potentially make microprocessor chips work 1,000 times faster October 20th, 2017

Self Assembly

Physicists gain new insights into nanosystems with spherical confinement: Enormous potential for the targeted delivery of pharmaceutical agents and the creation of tailored nanoparticles July 27th, 2017

Oddball enzyme provides easy path to synthetic biomaterials May 17th, 2017

Nanotubes that build themselves April 14th, 2017

Nanocages for gold particles: what is happening inside? March 16th, 2017

Announcements

Nanobiotix completes patient inclusion for Phase II/III trial of NBTXR3 in soft tissue sarcoma October 23rd, 2017

Arrowhead Pharmaceuticals Reports Inducement Grants under NASDAQ Marketplace Rule 5635(c)(4) October 23rd, 2017

Researchers bring optical communication onto silicon chips: Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers October 23rd, 2017

Nanotube fiber antennas as capable as copper: Rice University researchers show their flexible fibers work well but weigh much less October 23rd, 2017

Military

Nanotube fiber antennas as capable as copper: Rice University researchers show their flexible fibers work well but weigh much less October 23rd, 2017

Long nanotubes make strong fibers: Rice University researchers advance characterization, purification of nanotube wires and films October 17th, 2017

Rice U. study: Vibrating nanoparticles interact: Placing nanodisks in groups can change their vibrational frequencies October 16th, 2017

On the road to fire-free, lithium-ion batteries made with asphalt October 12th, 2017

Nanobiotechnology

Nanobiotix completes patient inclusion for Phase II/III trial of NBTXR3 in soft tissue sarcoma October 23rd, 2017

Arrowhead Pharmaceuticals Reports Inducement Grants under NASDAQ Marketplace Rule 5635(c)(4) October 23rd, 2017

Arrowhead Presents Promising Preclinical Data on Development of ARO-AAT for Treatment of Alpha-1 Liver Disease at Liver Meeting(R) 2017 October 23rd, 2017

Spinning strands hint at folding dynamics: Rice University lab uses magnetic beads to model microscopic proteins, polymers October 17th, 2017

Photonics/Optics/Lasers

Researchers bring optical communication onto silicon chips: Ultrathin films of a semiconductor that emits and detects light can be stacked on top of silicon wafers October 23rd, 2017

A step closer to understanding quantum mechanics: Swansea University’s physicists develop a new quantum simulation protocol October 22nd, 2017

Creation of coherent states in molecules by incoherent electrons October 21st, 2017

Novel 'converter' heralds breakthrough in ultra-fast data processing at nanoscale: Invention bagged four patents and could potentially make microprocessor chips work 1,000 times faster October 20th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project