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 Supersonic waves may help electronics beat the heat
18.05.2018 | DOE/Oak Ridge National Laboratory

nachricht Researchers control the properties of graphene transistors using pressure
17.05.2018 | Columbia 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: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>