Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Argonne researchers use electric field to manipulate tiny particles

26.03.2003


Intricate patterns formed by granular materials under the influence of electrostatic fields have scientists at the U.S. Department of Energy’s Argonne National Laboratory dreaming of new ways to create smaller structures for nanotechnologies. With a combination of electric fields and fluid mixtures, researchers Igor Aronson, Maksim Sapozhnikov, Yuri Tolmachev and Wai Kwok can cause tiny spheres of bronze and other metals to self-assemble into crystalline patterns, honeycombs, pulsating rings and bizarre two-lobed structures that whirl like tiny propellers. Such self-assembling behavior could be exploited to create the next generation nanostructures or tiny micromechanical devices. Their work has been reported in the Physical Review Letters (Phys. Rev. Lett. 90, 114301, 2003).



The research started about four years ago, when Igor Aronson was studying the surprisingly regular patterns formed when granular materials like sand are vibrated, seeking clues to the dynamics of such substances. "Despite about a thousand years of practical experience, we still don’t completely understand granular materials," Aronson said. "They can display the properties of solids or liquids, and behaviors that defy conventional physics."

Aronson and colleagues investigated the reaction of a very fine granular material in an electrostatic field. They placed a quarter-teaspoon of 100-micron bronze spheres between two transparent sheets coated with conducting material. Under high voltage, each bronze sphere acquires a charge from the bottom plate and is attracted to the upper sheet. The spheres reverse charge when they hit the upper sheet and are repelled back toward the lower sheet. As the process repeats 40 times per second, the bronze particles form a shimmering "gas" between the two plates. Groups of particles, responding to the electric field from the plates and from each other, tend to cluster together and coalesce into large, random groups.


Maksim Sapozhnikov, a postdoctoral researcher working under Aronson’s supervision, then filled the electrostatic cell with various non-conducting fluids, including toluene, octane and others. The results were essentially random until he tried phenotole, a colorless, oily fluid used in medicines and dyes. Then came the surprise - at around 1,000 volts, the particles began to form regular patterns. By varying the voltage, the spacing between the plates and the amount of conductive fluid in the mix, the researchers found they could create a regularly spaced array of dots (crystals), honeycombs and other forms.

The results then were reproduced with other dielectric liquids mixed with small amount of ethanol to control the electrical conductivity of the solution.

"Particles interact with each other and create hydrodynamic forces in the liquid. These interactions create the patterns," Aronson said. "You can actually ’tune’ the patterns by adding impurities to the liquid."

But the patterns aren’t always static. The particles can form rings that grow, absorb other clusters of particles, then burst open. Sometimes madly spinning strange creatures are formed. "They grow, they rotate, they do all kinds of crazy things," Aronson said. "The rotation, especially, is still not understood. The physics are complex, and we only partially understand them."

The ability of some materials to organize themselves into repeating patterns is of special interest to nanotechnologists. Tiny clusters of particles - measured in billionths of a meter, or about 1/500th the width of a human hair - exhibit different properties than their larger bulk counterparts. Argonne researchers have learned that they are more chemically reactive, exhibit new electronic properties and can be used to create materials that are stronger, tougher and more resistant to friction and wear than bulk materials.

Getting nanometer-sized particles to self-assemble into useful structures is one of the field’s most difficult challenges. Self-assembly techniques are usually driven by thermodynamic forces, which dictate the type of complex pattern formation.

"This electrostatic method provides an additional way to control the self-assembly process," Aronson said. "It’s another ’handle’ we can use to manipulate the particles." More information and movies of the particles in motion are online at http://www.msd.anl.gov/groups/sm/granphy/.

The nation’s first national laboratory, Argonne National Laboratory supports basic and applied scientific research across a wide spectrum of disciplines, ranging from high energy physics to climatology and biotechnology. Since 1990, Argonne has worked with more than 600 companies and numerous federal agencies and other organizations to help advance America’s scientific leadership and prepare the nation for the future. Argonne is operated by the University of Chicago as part of the U.S. Department of Energy national laboratory system.


###

Donna Jones Pelkie | EurekAlert!
Further information:
http://www.anl.gov/

More articles from Physics and Astronomy:

nachricht Nanotechnology for energy materials: Electrodes like leaf veins
27.09.2016 | Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

nachricht First quantum photonic circuit with electrically driven light source
27.09.2016 | Westfälische Wilhelms-Universität Münster

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

 
Latest News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

New switch decides between genome repair and death of cells

27.09.2016 | Life Sciences

Nanotechnology for energy materials: Electrodes like leaf veins

27.09.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>