Carbon Composite Material Could Function as Ersatz Nerve Bundles

Employing a technique for processing carbon nanobubes, researchers at the Oak Ridge National Laboratory (Oak Ridge, TN) are laying the groundwork for a material that could one day mimick the human nervous system, enabling the development of bionic devices.

"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," remarks Ilia Ivanov, a researcher at the Center for Nanophase Materials Sciences Division. "There, you would take the glass tube, heat it up, and pull, or draw, as soon as the glass became soft."

Ivanov and John 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 can make fibers just four times thicker than a human hair containing 19,600 submicron channels, each of which is filled with conducting carbon. Because each carbon nanotube-containing channel is electrically insulated from its neighbors by glass, it can be used as an individual communication channel.

While these nanostructures have electrical and other properties that make them attractive for 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 the wires required to match the density of receptors at even the fingertips would make it impossible to rely on the use of these nanostructures. 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," Ivanov says. "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," he adds. "So in terms of density of channels, we are already in the range needed for 17,000 receptors in the hand."

Ultimately, Ivanov says, the goal is to duplicate the function of a living system by combining the existing technology of glass-fiber drawing with the multifunctionality of submicron-scale carbon nanotubes.

More information on this research can be obtained from the Oak Ridge National Laboratory.