Featured Research

from universities, journals, and other organizations

Physicist Demonstrates How Light Can Be Used To Remotely Operate Micromachines

Date:
May 31, 2007
Source:
University of California - Riverside
Summary:
Scientists have demonstrated in the laboratory that the Casimir force -- the small attractive force that acts between two close parallel uncharged conducting plates -- can be changed using a beam of light, making the remote operation of micromachines a possibility.

A research team led by Umar Mohideen, a physicist at the University of California, Riverside, has demonstrated in the laboratory that the Casimir force -- the small attractive force that acts between two close parallel uncharged conducting plates -- can be changed using a beam of light, making the remote operation of micromachines a possibility.

The Casimir force results when the properties of "virtual photons" are modified. While a photon is the carrier particle of electromagnetic interactions, a virtual photon is a particle that exists for so brief an instant as an intermediary in a process that it can never be directly observed.

Because virtual photons are ever-present in empty space, studying the Casimir force allows physicists to learn the properties of the quantum nature of space.

In their study, Mohideen and his colleagues used a ball and a flat plate to simulate two parallel plates. "Where the ball and plate are close to each other, the surfaces are considered to be almost parallel at microscopic distances," said Mohideen, a professor of physics in the Department of Physics and Astronomy.

In each of his experiments, the ball (diameter 200 microns) was made of gold, a chemically clean metal that does not tarnish; only the material that made up the flat plate varied from experiment to experiment.

In one such experiment, the researchers used a plate of silicon, a material commonly used in the semiconductor industry, and measured the "carrier density" or the number of electrons in the plate.

They then compared the Casimir force that arose each time between the gold ball and a series of silicon plates of different carrier densities. They found that the Casimir force was measurably different between the ball and any two silicon plates only when the carrier density of one plate was at least 10,000 times larger than the carrier density of the second plate.

"We then asked ourselves if it was possible to bring about this density difference in other ways," Mohideen said.

The researchers next experimented with the gold ball and a silicon plate with identical carrier densities. Training a beam of light on the plate, they were able to change the plate's carrier density by an amount that was enough to change the Casimir force between the plate and the ball.

When light is absorbed by silicon, photons are converted into positive and negative charges, Mohideen explained. It is the increase in the number of electrons (negative charges) that increases the Casimir force.

"Using this result, it should be possible now to make special probes that can check for changes in electron density," he added. "It can be used, too, to make new micromachines that can be remotely operated simply by using light."

Micromachines find applications in complex systems of tiny gears and levers. They are used to reroute light between optical fibers in optical communication. They also are used in accelerometers that can trigger an airbag in an accident.

"Because of the sensitivity associated with light, we can match theory with experiment with much more precision at a very small scale," Mohideen said. "This would help physicists better understand how a theory called the Lifshitz theory should be applied in experiments on the Casimir force."

The Lifshitz theory predicts that the strength of the Casimir force between two surfaces is dependent on the distance between the surfaces (the smaller the distance, the greater the force). The theory also predicts how the number of electrons in the surface changes the force, and gives an explanation of how virtual photons interact with electrons.

Next in their research, the physicists plan to improve the sensitivity of their experiments using more precise detection techniques. They will attempt, too, to understand exactly how electrons and virtual photons interact.

The researchers' study of the effect of light on the Casimir force appeared in the April 16 issue of Optics Express. Mohideen's coauthors are F. Chen, UCR; G. L. Klimchitskaya, North-West Technical University, St. Petersburg, Russia; and V. M. Mostepanenko, Noncommercial Partnership "Scientific Instruments," Moscow, Russia. The National Science Foundation and the U.S. Department of Energy provided support.

Work by Mohideen's team on how the Casimir force changes when a threshold carrier density difference is reached appeared in Physical Review Letters in October 2006.


Story Source:

The above story is based on materials provided by University of California - Riverside. Note: Materials may be edited for content and length.


Cite This Page:

University of California - Riverside. "Physicist Demonstrates How Light Can Be Used To Remotely Operate Micromachines." ScienceDaily. ScienceDaily, 31 May 2007. <www.sciencedaily.com/releases/2007/05/070531145609.htm>.
University of California - Riverside. (2007, May 31). Physicist Demonstrates How Light Can Be Used To Remotely Operate Micromachines. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2007/05/070531145609.htm
University of California - Riverside. "Physicist Demonstrates How Light Can Be Used To Remotely Operate Micromachines." ScienceDaily. www.sciencedaily.com/releases/2007/05/070531145609.htm (accessed July 29, 2014).

Share This




More Matter & Energy News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Lithium Battery 'Holy Grail' Could Provide 4 Times The Power

Newsy (July 28, 2014) Stanford University published its findings for a "pure" lithium ion battery that could have our everyday devices and electric cars running longer. Video provided by Newsy
Powered by NewsLook.com
The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Shipping Crates Get New 'lease' On Life

Shipping Crates Get New 'lease' On Life

Reuters - Business Video Online (July 25, 2014) Shipping containers have been piling up as America imports more than it exports. Some university students in Washington D.C. are set to get a first-hand lesson in recycling. Their housing is being built using refashioned shipping containers. Lily Jamali reports. Video provided by Reuters
Powered by NewsLook.com
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

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