Featured Research

from universities, journals, and other organizations

Weighing The Very Small: "Nanobalance" Based On Carbon Nanotubes Shows New Application For Nanomechanics

Date:
March 8, 1999
Source:
Georgia Institute Of Technology
Summary:
A "nanobalance" small enough to weigh viruses and other sub-micron scale particles is one application for newly-discovered electronic and micromechanical properties of carbon nanotubes.

A "nanobalance" small enough to weigh viruses and other sub-micron scale particles is one application for newly-discovered electronic and micromechanical properties of carbon nanotubes.

Related Articles


A report in the March 5 issue of the journal Science describes how electrical voltage can be used to induce electrostatic deflection and vibrational resonance in individual carbon nanotubes. This ability to selectively deflect or induce resonance in individual nanotubes opens new potential micromechanical applications for the tiny structures, which are smaller than the finest features on modern microcircuits.

Researchers at the Georgia Institute of Technology studied the behavior of multiwalled nanotubes using a transmission electron microscope with a unique sample holder designed and built by Dr. Philippe Poncharal of Georgia Tech. The holder allowed them to rotate specimens, apply electrical voltage and observe many fundamental effects. The work was sponsored by the U.S. National Science Foundation and the U.S. Army Research Laboratory.

"This opens a broad new field of study," said Dr. Walter de Heer, professor in Georgia Tech's School of Physics. "To show that we can manipulate individual carbon nanotubes while examining them with an electron microscope is breaking new ground. This allows us to use the microscope in a much more interactive way with direct visualization and control that enable us to manipulate the nanotubes the way you would manipulate macroscopic objects on a desktop."

By applying a charge to a nanotube placed near an oppositely-charged probe, the researchers were able to severely bend the tiny structures.

"We can bend a nanotube almost 90 degrees, and it will still recover and straighten out," said Dr. Z.L. Wang, professor in Georgia Tech's School of Materials Science and Engineering. "You can keep on bending them and they will not break. This shows that although nanotubes are very rigid, they have an extremely high elastic limit. Very few materials can do this without damage."

The researchers created resonance in the nanotubes by applying an oscillating voltage. By carefully tuning the oscillation frequency, they were able to induce resonant vibration in nanotubes. Resonant nodes appear in the tubes just as they would in a vibrating guitar string. Each nanotube resonates at a specific frequency that depends on its length, diameter, density and elastic properties.

"You can select which one you want to examine and make it resonate," Poncharal explained. "Then you turn up the frequency and another one will resonate."

The resonance occurs in a very narrow range, allowing the researchers to measure the damping properties of the nanotubes. "These resonances were very narrow, so finding them was like tuning for an unknown radio station -- you just keep looking," noted de Heer.

The researchers also studied the mechanism by which the nanotubes bend.

"One of the most important characteristics of nanotubes is that they are extremely rigid and strong," said de Heer. "That's true when they are very thin. But we have found that as you start making them thicker and thicker, their elastic properties become weaker and weaker and they become softer and softer. They enter a new mode of bending."

Using high-resolution transmission electron microscopy, Dr. Daniel Ugarte of the Laboratorio National de Luz Sincotron in Brazil observed a rippling on the surface of thick nanotubes as they deflected. This confirms that bending in these tubes is different.

"The elastic constant is varying as a function of its diameter, which is unexpected for a general material. This elastic constant should be an intrinsic property of the tubes, rather than depending on its geometry or size," explained Wang.

Using the tiny tubes as a "nanobalance" depends on the ability to calculate changes in the resonant frequency that occur with placement of an object onto a nanotube.

"This is comparable to putting an object on the end of a spring and oscillating it," said de Heer. "By knowing the properties of the spring, you can measure the mass of the object. We can use the nanotube like a standard calibrated spring."

Applying this technique, the researchers were able to measure the mass of a 22 femtogram graphite particle attached to the end of a resonating nanotube. "There is no other way to weigh accurately something that small," he noted.

Beyond the small particle measured so far, the researchers believe their nanobalance could be useful for determining the mass of other objects on the femtogram to picogram size range -- such as viruses. Samples would be attached to tubes through condensation or liquid application of suspended particles.

(Note: A femtogram is 10-15 grams.)


Story Source:

The above story is based on materials provided by Georgia Institute Of Technology. Note: Materials may be edited for content and length.


Cite This Page:

Georgia Institute Of Technology. "Weighing The Very Small: "Nanobalance" Based On Carbon Nanotubes Shows New Application For Nanomechanics." ScienceDaily. ScienceDaily, 8 March 1999. <www.sciencedaily.com/releases/1999/03/990308054523.htm>.
Georgia Institute Of Technology. (1999, March 8). Weighing The Very Small: "Nanobalance" Based On Carbon Nanotubes Shows New Application For Nanomechanics. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/1999/03/990308054523.htm
Georgia Institute Of Technology. "Weighing The Very Small: "Nanobalance" Based On Carbon Nanotubes Shows New Application For Nanomechanics." ScienceDaily. www.sciencedaily.com/releases/1999/03/990308054523.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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