Stories tagged nanotubes

John Hart, a professor at the University of Michigan, has created a super-small tribute to President-elect Obama using 150 million nanotubes. (Each one is less than a millimeter in diameter and can only be seen through a microscope.)

Jul
06
2008

The shrinking radio: Courtesy Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley.
The shrinking radio: Courtesy Zettl Research Group, Lawrence Berkeley National Laboratory and University of California at Berkeley.Courtesy Zettl Research Group

Tiniest radio yet

A fully integrated radio receiver, orders-of-magnitude smaller than any previous radio, was made from a single carbon nanotube (CNT).

When a radio wave of a specific frequency impinges on the nanotube it begins to vibrate vigorously. An electric field applied to the nanotube forces electrons to be emitted from its tip.

This nanotube radio is over 10,000,000,000,000,000,000 times smaller than the Philco vacuum tube radio from the 1930s.

The single nanotube serves, at once, as all major components of a radio: antenna, tuner, amplifier, and demodulator. (Berkely physics research)

See and hear a nano radio

Videos from an electron microscope view of the nanotube radio playing two different songs are linked below.

A large scale model: photo by ARendle on flickr.com
A large scale model: photo by ARendle on flickr.com
Check it out here.
A tiny Mel Gibson has been dispatched to the scene. Or maybe it was the normal Mel Gibson. I didn't read the article that carefully.

Mar
09
2007

New nano material a black hole for reflections.

Silica nanorods make a super dark surface.: This SEM image shows the silica nanorods mounted at exactly 45 degrees which makes the surface super anti-reflective.
Silica nanorods make a super dark surface.: This SEM image shows the silica nanorods mounted at exactly 45 degrees which makes the surface super anti-reflective.

Scientists at Rensselaer Polytechnic Institute have created a material that reflects virtually no light. By depositing layers of silica nanorods at an angle of 45 degrees on top of a thin film of aluminum nitride, a new world record has been set for anti-reflective surfacing.

The technique allows the researchers to strongly reduce or even eliminate reflection at all wavelengths and incoming angles of light, Schubert said. Conventional anti-reflection coatings, although widely used, work only at a single wavelength and when the light source is positioned directly perpendicular to the material. PhysOrg.com

Where will this make a difference?

The new optical coating could find use in just about any application where light travels into or out of a material, such as:

  • More efficient solar cells
  • Brighter LEDs
  • High-reflectance mirrors
  • Black body radiation
  • Optical interconnects (photonics)

RPI press release here:

Rensselaer Polytechnic Institute press release

May
26
2006


Nano light emitters: Credit: Lorelle Mansfield/NIST NIST "grows" semiconductor nanowires that emit ultraviolet light as part of a project to make prototype nano-lasers and other devices and the measurement tools needed to characterize them. Electron micrograph shows the gall
Researchers at the National Institute of Standards and Technology (NIST) are growing nanowires made of gallium nitride alloys and making prototype devices and nanometrology tools. The wires are grown under high vacuum by depositing atoms layer by layer on a silicon crystal.
When excited with a laser or electric current, the wires emit an intense glow in the ultraviolet or visible parts of the spectrum, depending on the alloy composition.
The NIST team has used the nanowires to make a number of prototype devices, including light-emitting diodes, field-effect transistors, and nanowire "bridge" structures that may be useful in sensors and nanoscale mechanical resonators.
Nanolight sources may have many applications, including "lab on a chip" devices for identifying chemicals and biological agents, scanning-probe microscope tips for imaging objects smaller than is currently possible, or ultra-precise tools for laser surgery and electronics manufacturing.
Source: NIST Tech Beat

Feb
16
2006

That's the promise of a new battery developed by researchers at MIT's Laboratory for Electromagnetic and Electronic Systems. They're using nanotechnology to improve an energy storage device called an ultracapacitor.


Nanotubes: (Photo courtesy Riccardo Signorelli, Laboratory for Electromagnetic and Electrical Studies, MIT)

Unlike regular batteries, which can generate electricity from a chemical reaction, capacitors store energy as an electrical field. Ultracapacitors can store lots of energy for a long time, but they need to be much bigger than regular batteries to hold the same amount of electricity. The new MIT technique, uses nanotechnology to improve the storage capacity of existing capacitors and may eventually help to make them smaller.

How does it work?

A battery has two electrodes, or terminals, one positive and one negative. Inside the battery are chemicals that react with each other to produce electrons. The electrons collect on the negative terminal of the battery. When you connect the terminals with a wire, you can use the flow of electrons to power things. A capacitor also has two electrodes-metal plates separated by a material that doesn't conduct electricity. A positive charge builds up on one plate, and a negative charge builds up on the other. When you connect the two electrodes, they discharge their energy. A battery can actually "create" energy by changing chemicals into electricity while a capacitor can only store energy it has been charged with.


Ultracapacitor in a hybrid engine: An ultracapacitor in a hybrid gas/electric engine for a car.

Today's ultracapacitors use electrodes made of activated carbon; the carbon is porous, so it has lots of surface area for the electrons to build up on. But the pores are irregular in size and shape, which reduces efficiency. That's why capacitors have to be big. But the MIT ultracapacitor has electrodes of vertically aligned carbon nanotubes, each one thirty-thousandth the width of a human hair. The regular shape and alignment of the nanotubes greatly increases the surface area, making the ultracapacitor very efficient at storing electrons.


Carbon nanotubes: Vertically aligned carbon nanotubes have lots of surface area to store electrons. (Photo courtesy Riccardo Signorelli, Laboratory for Electromagnetic and Electrical Systems, MIT)

Smaller is better

Ultracapacitors are long lasting and quick-charging. Storing energy at the atomic level with nanotubes means that they can finally be small, too, perhaps eventually powering everything from flashlights and cell phones to hybrid cars and missile-guidance systems.

Make it at the Museum

Stop by the Museum on Saturday, February 18th. You can make a pop can flashlight and test some conventional batteries. Experiment with electricity, circuits, and capacitors more at the AC/DC electricity bench in the Experiment Gallery.