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Topic Name: New bendy sensors are using single-walled carbon nanotubes (SWNTs)
Category: Advanced Materials
Research persons: Sun-Ho Kang & others of Argonne National Laboratory
Location: Argonne National Laboratory,9700 S. Cass Avenue,Argonne, IL 60439.,Phone: 630/252-2000, United States
Details
In recent years, Americans have been intrigued by the promise of
hydrogen-powered vehicles. But experts have judged that several technology
problems must be resolved before they are more than a novelty.Recently,
scientists at the U.S. Department of Energy's Argonne National Laboratory have
used their insights into nanomaterials to create bendy hydrogen sensors, which
are at the heart of hydrogen fuel cells used in hydrogen vehicles.
In comparison to previously designed hydrogen sensors, which are rigid and
use expensive, pure palladium, the new sensors are bendy and use single-walled
carbon nanotubes (SWNTs) to improve efficiency and reduce cost. The development
of these hydrogen sensors will help to ensure economical, environmental and
societal safety, as the nation is realizing the potential for a more
hydrogen-based economy.
Yugang Sun and H. Hau Wang, researchers in Argonne's
Center for Nanoscale Materials and
Materials Science Division,
respectively, fabricated the new sensing devices using a two-step process
separated by high and low temperatures. First, at around 900 degrees C,
researchers grow SWNTs on a silicon substrate using chemical vapor deposition.
Then, researchers transfer the SWNTs onto a plastic substrate at temperatures
lower than 150 degrees C using a technique called dry transfer printing.
This precise process is what allows the film of nanotubes to form on the
plastic, after which the palladium nanoparticles can be deposited on the SWNTs
to make the sensors. The palladium nanoparticles play an important role in
increasing the interaction between hydrogen and the SWNTs to enhance the change
of resistance of the device when it is exposed to hydrogen molecules.
According to Sun, these sensors exhibit excellent sensing performance in
terms of high sensitivity, fast response time and quick recovery, and the use of
plastic sheets reduces their overall weight and increases their mechanical
flexibility and shock resistance. The sensors are also able to be wrapped around
curved surfaces, and this proves useful in many applications, notably in
vehicles, aircraft and portable electronics.
“The leakage of hydrogen caused by tiny pinholes in the pipe of a space
shuttle, for example, could not be easily detected by individual rigid detectors
because the locations of pinholes are not predetermined,” said Sun. “However,
laminating a dense array of flexible sensors on the surfaces of the pipe can
detect any hydrogen leakage prior to diffusion to alert control units to take
action.”
Flexible hydrogen sensors show a change of 75 percent in their resistance
when exposed to hydrogen at a concentration of 0.05 percent in air. The devices
can detect the presence of 1 percent hydrogen at room temperature in 3 seconds.
Even after bending—with a bending radius of approximately 7.5 mm—and relaxing
2,000 times, the devices still perform with as much effectiveness.
About Researchers:
Sun-Ho Kang, Materials Scientist, phone: 630/252-4212, fax: 630/252-4176,
e-mail: kangs@cmt.anl.gov
- PhD, Materials Science and Engineering, Seoul National University, Korea
- Development of high-power and high-energy lithium-ion batteries
- Synthesis of spherical metal hydroxide and metal carbonate
- 35 peer-reviewed publications, 20 technical presentations, 2 patents
Funded:
With employees from more than 60 nations, Argonne National Laboratory brings
the world's brightest scientists and engineers together to find exciting and
creative new solutions to pressing national problems in science and technology.
The nation's first national laboratory, Argonne conducts leading-edge basic and
applied scientific research in virtually every scientific discipline. Argonne
researchers work closely with researchers from hundreds of companies,
universities, and federal, state and municipal agencies to help them solve their
specific problems, advance America 's scientific leadership and prepare the
nation for a better future. Argonne is managed by
UChicago Argonne,
LLC for the U.S. Department
of Energy's Office of
Science
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