Featured Research

from universities, journals, and other organizations

Argonne Researchers Use Electric Field To Manipulate Tiny Particles

Date:
March 26, 2003
Source:
Argonne National Laboratory
Summary:
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.

ARGONNE, Ill. (March 25, 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.


Story Source:

The above story is based on materials provided by Argonne National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Argonne National Laboratory. "Argonne Researchers Use Electric Field To Manipulate Tiny Particles." ScienceDaily. ScienceDaily, 26 March 2003. <www.sciencedaily.com/releases/2003/03/030326073749.htm>.
Argonne National Laboratory. (2003, March 26). Argonne Researchers Use Electric Field To Manipulate Tiny Particles. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2003/03/030326073749.htm
Argonne National Laboratory. "Argonne Researchers Use Electric Field To Manipulate Tiny Particles." ScienceDaily. www.sciencedaily.com/releases/2003/03/030326073749.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins