Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Big power from tiny wires

A carbon nanotube (shown in illustration) can produce a very rapid wave of power when it is coated by a layer of fuel and ignited, so that heat travels along the tube. Graphic: Christine Daniloff
A carbon nanotube (shown in illustration) can produce a very rapid wave of power when it is coated by a layer of fuel and ignited, so that heat travels along the tube. Graphic: Christine Daniloff

Abstract:
New discovery shows carbon nanotubes can produce powerful waves that could be harnessed for new energy systems.

By David L. Chandler, MIT News Office

Big power from tiny wires

Cambridge, MA | Posted on March 8th, 2010

A team of scientists at MIT have discovered a previously unknown phenomenon that can cause powerful waves of energy to shoot through minuscule wires known as carbon nanotubes. The discovery could lead to a new way of producing electricity, the researchers say.

The phenomenon, described as thermopower waves, "opens up a new area of energy research, which is rare," says Michael Strano, MIT's Charles and Hilda Roddey Associate Professor of Chemical Engineering, who was the senior author of a paper describing the new findings that appeared in Nature Materials on March 7. The lead author was Wonjoon Choi, a doctoral student in mechanical engineering.

Like a collection of flotsam propelled along the surface by waves traveling across the ocean, it turns out that a thermal wave — a moving pulse of heat — traveling along a microscopic wire can drive electrons along, creating an electrical current.

The key ingredient in the recipe is carbon nanotubes — submicroscopic hollow tubes made of a chicken-wire-like lattice of carbon atoms. These tubes, just a few billionths of a meter (nanometers) in diameter, are part of a family of novel carbon molecules, including buckyballs and graphene sheets, that have been the subject of intensive worldwide research over the last two decades.

A previously unknown phenomenon

In the new experiments, each of these electrically and thermally conductive nanotubes was coated with a layer of a reactive fuel that can produce heat by decomposing. This fuel was then ignited at one end of the nanotube using either a laser beam or a high-voltage spark, and the result was a fast-moving thermal wave traveling along the length of the carbon nanotube like a flame speeding along the length of a lit fuse. Heat from the fuel goes into the nanotube, where it travels thousands of times faster than in the fuel itself. As the heat feeds back to the fuel coating, a thermal wave is created that is guided along the nanotube. With a temperature of 3,000 kelvins, this ring of heat speeds along the tube 10,000 times faster than the normal spread of this chemical reaction. The heating produced by that combustion, it turns out, also pushes electrons along the tube, creating a substantial electrical current.

Combustion waves — like this pulse of heat hurtling along a wire — "have been studied mathematically for more than 100 years," Strano says, but he was the first to predict that such waves could be guided by a nanotube or nanowire and that this wave of heat could push an electrical current along that wire.

In the group's initial experiments, Strano says, when they wired up the carbon nanotubes with their fuel coating in order to study the reaction, "lo and behold, we were really surprised by the size of the resulting voltage peak" that propagated along the wire.

After further development, the system now puts out energy, in proportion to its weight, about 100 times greater than an equivalent weight of lithium-ion battery.

The amount of power released, he says, is much greater than that predicted by thermoelectric calculations. While many semiconductor materials can produce an electric potential when heated, through something called the Seebeck effect, that effect is very weak in carbon. "There's something else happening here," he says. "We call it electron entrainment, since part of the current appears to scale with wave velocity."

The thermal wave, he explains, appears to be entraining the electrical charge carriers (either electrons or electron holes) just as an ocean wave can pick up and carry a collection of debris along the surface. This important property is responsible for the high power produced by the system, Strano says.

Exploring possible applications

Because this is such a new discovery, he says, it's hard to predict exactly what the practical applications will be. But he suggests that one possible application would be in enabling new kinds of ultra-small electronic devices — for example, devices the size of grains of rice, perhaps with sensors or treatment devices that could be injected into the body. Or it could lead to "environmental sensors that could be scattered like dust in the air," he says.

In theory, he says, such devices could maintain their power indefinitely until used, unlike batteries whose charges leak away gradually as they sit unused. And while the individual nanowires are tiny, Strano suggests that they could be made in large arrays to supply significant amounts of power for larger devices.

The researchers also plan to pursue another aspect of their theory: that by using different kinds of reactive materials for the coating, the wave front could oscillate, thus producing an alternating current. That would open up a variety of possibilities, Strano says, because alternating current is the basis for radio waves such as cell phone transmissions, but present energy-storage systems all produce direct current. "Our theory predicted these oscillations before we began to observe them in our data," he says.

Also, the present versions of the system have low efficiency, because a great deal of power is being given off as heat and light. The team plans to work on improving that efficiency.

Ray Baughman, director of the Nanotech Institute at the University of Texas at Dallas, who was not involved in this work, calls the research "stellar."

The work, Baughman says, "started with a seminal initial idea, which some might find crazy, and provided exciting experimental results, the discovery of new phenomena, deep theoretical understanding, and prospects for applications." Because it uncovered a previously unknown phenomenon, he says, it could open up "an exciting new area of investigation."

####

About MIT
The mission of MIT is to advance knowledge and educate students in science, technology and other areas of scholarship that will best serve the nation and the world in the 21st century — whether the focus is cancer, energy, economics or literature.

For more information, please click here

Copyright © MIT

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Arrowhead Receives Regulatory Clearance to Begin Phase 1 Study of ARO-AAT for Treatment of Alpha-1 Liver Disease February 22nd, 2018

MEMS chips get metatlenses: Combining metasurface lenses with MEMS technology could add high-speed scanning and enhance focusing capability of optical systems February 21st, 2018

Atomic structure of ultrasound material not what anyone expected February 21st, 2018

Oxford Instruments announces Dr Kate Ross as winner of the 2018 Lee Osheroff Richardson Science Prize for North and South America February 20th, 2018

Possible Futures

MEMS chips get metatlenses: Combining metasurface lenses with MEMS technology could add high-speed scanning and enhance focusing capability of optical systems February 21st, 2018

Atomic structure of ultrasound material not what anyone expected February 21st, 2018

Computers aid discovery of new, inexpensive material to make LEDs with high color quality February 20th, 2018

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Nanotubes/Buckyballs/Fullerenes/Nanorods

Nanotube fibers in a jiffy: Rice University lab makes short nanotube samples by hand to dramatically cut production time January 11th, 2018

Touchy nanotubes work better when clean: Rice, Swansea scientists show that decontaminating nanotubes can simplify nanoscale devices January 4th, 2018

Paving the way for a non-electric battery to store solar energy: UMass Amherst scientists say a polymer chain organized like a string of Christmas lights assists energy storage December 22nd, 2017

Nanotubes go with the flow to penetrate brain tissue: Rice University scientists, engineers develop microfluidic devices, microelectrodes for gentle implantation December 19th, 2017

Sensors

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Leti Chief Scientist Barbara De Salvo Will Help Kick Off ISSCC 2018 with Opening-Day Keynote: In Addition, Leti Scientists Will Present and Demo New Technology for Piezoelectric Energy Harvesting February 8th, 2018

Engineers develop flexible, water-repellent graphene circuits for washable electronics January 24th, 2018

Leti to Demo New Curving Technology at Photonics West that Improves Performance of Optical Components January 18th, 2018

Discoveries

MEMS chips get metatlenses: Combining metasurface lenses with MEMS technology could add high-speed scanning and enhance focusing capability of optical systems February 21st, 2018

Atomic structure of ultrasound material not what anyone expected February 21st, 2018

Computers aid discovery of new, inexpensive material to make LEDs with high color quality February 20th, 2018

Unconventional superconductor may be used to create quantum computers of the future: They have probably succeeded in creating a topological superconductor February 19th, 2018

Announcements

Arrowhead Receives Regulatory Clearance to Begin Phase 1 Study of ARO-AAT for Treatment of Alpha-1 Liver Disease February 22nd, 2018

MEMS chips get metatlenses: Combining metasurface lenses with MEMS technology could add high-speed scanning and enhance focusing capability of optical systems February 21st, 2018

Atomic structure of ultrasound material not what anyone expected February 21st, 2018

Oxford Instruments announces Dr Kate Ross as winner of the 2018 Lee Osheroff Richardson Science Prize for North and South America February 20th, 2018

Energy

Round-the-clock power from smart bowties February 5th, 2018

Silk fibers could be high-tech ‘natural metamaterials’ January 31st, 2018

A simple new approach to plastic solar cells: Osaka University researchers intelligently design new highly efficient organic solar cells based on amorphous electronic materials with potential for easy printing January 28th, 2018

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project