New ORNL carbon composite holds promise for bionics

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New ORNL carbon composite holds promise for bionics

http://www.ornl.gov/info/press_releases/get_press_release.cfm?ReleaseNumber=mr20\

100422-00

Mimicking the human nervous system for bionic applications could become a

reality with the help of a method developed at Oak Ridge National Laboratory to

process carbon nanotubes.

While these nanostructures have electrical and other properties that make them

attractive to use as artificial neural bundles in prosthetic devices, the

challenge has been to make bundles with enough fibers to match that of a real

neuron bundle. With current technology, the weight alone of wires required to

match the density of receptors at even the fingertips would make it impossible

to accommodate. Now, by adapting conventional glass fiber drawing technology to

process carbon nanotubes into multichannel assemblies, researchers believe they

are on a path that could lead to a breakthrough.

" Our goal is to use our discovery to mimic nature's design using artificial

sensors to effectively restore a person's ability to sense objects and

temperatures, " said Ilia Ivanov, a researcher in the Center for Nanophase

Materials Sciences Division. Ivanov and colleagues at ORNL recently published a

paper in Nanotechnology that outlines the method of processing loose carbon

nanotubes into a bundle with nearly 20,000 individual channels.

Ultimately, the goal is to duplicate the function of a living system by

combining the existing technology of glass fiber drawing with the

multi-functionality of sub-micron (0.4 micron) scale carbon nanotubes, according

to Ivanov, who described the process.

" We make this material in a way similar to what you may have done in high school

when making a glass capillary over a Bunsen burner, " Ivanov said. " There, you

would take the glass tube, heat it up and pull, or draw, as soon as the glass

became soft. "

Ivanov and Simpson of the Measurement Science and Systems Engineering

Division are doing something similar except they use thousands of glass tubes

filled with carbon nanotube powder. After several draw cycles, they demonstrated

that they could make fibers just four times thicker than a human hair containing

19,600 sub-micron channels with each channel filled with conducting carbon. Each

carbon nanotube-containing channel is electrically insulated from its neighbors

by glass so it can be used as an individual communication channel.

With this achievement, the researchers are moving closer to realizing one of

their goals.

" The human hand has a density of receptors at the fingertips of about 2,500 per

square centimeter and about 17,000 tactile receptors in the hand, " Ivanov said.

" So in terms of density of channels, we are already in the range needed for

17,000 receptors in the hand. "

This multichannel composite has many other potential uses, including in

aeronautics and space applications, where low weight of conducting wires is

important,

The next steps are to make these channels highly conductive and then show sensor

communication through individual channels.

Other authors of the Nanotechnology paper, which was published in February, are

Troy Hendricks and Schaeffer of the Measurement Science and Systems

Engineering Division and Menchhofer of the Materials Science and Technology

Division. Initial carbon nanotube research was funded by the Scientific User

Facilities Division, DOE Office of Basic Energy Sciences. Processing research

was sponsored by the ORNL Laboratory Directed Research and Development program.

The Center for Nanophase Materials Sciences at ORNL is one of the five DOE

Nanoscale Science Research Centers, premier national user facilities for

interdisciplinary research at the nanoscale, supported by the DOE Office of

Science. Together the NSRCs comprise a suite of complementary facilities that

provide researchers with state-of-the-art capabilities to fabricate, process,

characterize and model nanoscale materials, and constitute the largest

infrastructure investment of the National Nanotechnology Initiative. The NSRCs

are located at DOE's Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge, Sandia

and Los Alamos national laboratories. For more information about the DOE NSRCs,

please visit http://nano.energy.gov.

UT-Battelle manages ORNL for the Department of Energy's Office of Science.