Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Carbon nanotube oscillator might weigh a single atom

16.09.2004


Using a carbon nanotube, Cornell University researchers have produced a tiny electromechanical oscillator that might be capable of weighing a single atom. The device, perhaps the smallest of its kind ever produced, can be tuned across a wide range of radio frequencies, and one day might replace bulky power-hungry elements in electronic circuits.



Recent research in nanoelectromechanical systems (NEMS) has focused on vibrating silicon rods so small that they oscillate at radio frequencies. By replacing the silicon rod with a carbon nanotube, the Cornell researchers have created an oscillator that is even smaller and very durable. Besides serving as a radio frequency circuit element, the new device has applications in mass sensing and basic research.

Paul McEuen, Cornell professor of physics, Vera Sazonova, Cornell graduate student in physics and Yuval Yaish, a visiting scientist in the Laboratory of Atomic and Solid State Physics (LASSP) at Cornell, report on the device in the latest issue (Sept. 16, 2004) of the journal Nature.


Carbon nanotubes are cylinders of carbon atoms arranged in a hexagonal pattern similar to that in the geodesic domes created by architect, inventor and mathematician Buckminster Fuller. Materials with this structure are called fullerenes in his honor, and fullerene spheres are known as buckyballs. A nanotube can be thought of as an elongated buckyball.

The Cornell device consists of a carbon nanotube from one to four nanometers in diameter and about one-and-a-half micrometers long, suspended between two electrodes above a conducting silicon plate. (A nanometer is one-billionth of a meter, the length of three silicon atoms in a row; a micrometer is one-millionth of a meter.) The tube is not stretched tight, but hangs like a chain between two posts in a shallow curve called a catenary.

The tube itself is a conductor, and when a voltage is applied between the tube and the underlying plate, electrostatic force attracts the tube to the plate. An alternating voltage sets up vibration as the tube is alternately attracted and repelled. A static voltage applied at the same time increases the tension on the tube, changing its frequency of vibration just as tightening or loosening a guitar string changes its pitch. The entire assembly of tube and plate behaves as a transistor, so the tube’s motion can be read out by measuring the current flow. Experimenting with various sizes and lengths of tubes, the researchers have made oscillators that tune over a range from 3 to 200 megaHertz (millions of cycles per second).

Such a tunable oscillator could be used as a detector in a radio-frequency device such as a cellular phone, which must constantly change its operating frequency to avoid conflicts with other phones. Like their larger cousins, nanotube oscillators also could be used for mass sensing. Since the frequency of vibration is a function of the mass of the vibrating string, adding a very small mass can change the frequency. Silicon rod oscillators have been used to weigh bacteria and viruses. "This is so much smaller that mass sensitivity should be that much higher," McEuen said. "We’re pushing the ultimate limit, maybe weighing individual atoms."

The researchers conducted their measurements in a vacuum. If air or any other gas were present, the gas molecules would adsorb, or collect in a condensed form, on the surface of the tube, changing its mass. So, McEuen says, nanotube oscillators could be used as gas detectors. One drawback, he points out, is that at present there is no way to mass-produce carbon nanotubes.

McEuen looks forward to studying the fundamental physics of the device. When cooled to cryogenic temperatures, he says, the nanotube acts like "a skinny quantum dot," or a sort of box full of electrons. "We can study the influence of individual electrons hopping on and off," he says. "What happens when you have a quantum dot that can wiggle?"

The Nature paper is titled "A Tunable Carbon Nanotube Electromechnical Oscillator." Other co-authors are Hande &†uml;stünel, a graduate student in physics, David Roundy, a LASSP postdoctoral associate and Tomás A. Arias, Cornell associate professor of physics. The work was funded by the National Science Foundation (NSF) and the Microelectronics Advanced Research Program (MARCO) Focus Center on Materials, Structures and Devices supported by the Semiconductor Research Corporation. The devices were fabricated at the NSF-funded Cornell Nanoscale Facility.

Related World Wide Web sites: The following sites provide additional information on this news release. Some might not be part of the Cornell University community, and Cornell has no control over their content or availability.
oMcEuen group: http://www.lassp.cornell.edu/lassp_data/mceuen/homepage/pubs.html

Bill Steele | EurekAlert!
Further information:
http://www.cornell.edu

More articles from Power and Electrical Engineering:

nachricht Engineers program tiny robots to move, think like insects
15.12.2017 | Cornell University

nachricht Electromagnetic water cloak eliminates drag and wake
12.12.2017 | Duke University

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Error-free into the Quantum Computer Age

A study carried out by an international team of researchers and published in the journal Physical Review X shows that ion-trap technologies available today are suitable for building large-scale quantum computers. The scientists introduce trapped-ion quantum error correction protocols that detect and correct processing errors.

In order to reach their full potential, today’s quantum computer prototypes have to meet specific criteria: First, they have to be made bigger, which means...

Im Focus: Search for planets with Carmenes successful

German and Spanish researchers plan, build and use modern spectrograph

Since 2016, German and Spanish researchers, among them scientists from the University of Göttingen, have been hunting for exoplanets with the “Carmenes”...

Im Focus: First-of-its-kind chemical oscillator offers new level of molecular control

DNA molecules that follow specific instructions could offer more precise molecular control of synthetic chemical systems, a discovery that opens the door for engineers to create molecular machines with new and complex behaviors.

Researchers have created chemical amplifiers and a chemical oscillator using a systematic method that has the potential to embed sophisticated circuit...

Im Focus: Long-lived storage of a photonic qubit for worldwide teleportation

MPQ scientists achieve long storage times for photonic quantum bits which break the lower bound for direct teleportation in a global quantum network.

Concerning the development of quantum memories for the realization of global quantum networks, scientists of the Quantum Dynamics Division led by Professor...

Im Focus: Electromagnetic water cloak eliminates drag and wake

Detailed calculations show water cloaks are feasible with today's technology

Researchers have developed a water cloaking concept based on electromagnetic forces that could eliminate an object's wake, greatly reducing its drag while...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

AKL’18: The opportunities and challenges of digitalization in the laser industry

07.12.2017 | Event News

 
Latest News

The body's street sweepers

18.12.2017 | Life Sciences

Fast flowing heat in layered material heterostructures

18.12.2017 | Materials Sciences

Life on the edge prepares plants for climate change

18.12.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>