Replacing the
braided outer conductor in coaxial data cables with a coat of conductive
carbon nanotubes
saves significant weight, according to Rice University researchers.
(Credit: Pasquali
Lab/Rice University)
(January 27, 2016) Rice
University scientists replace metal with carbon nanotubes for aerospace use
Common coaxial cables could be made 50 percent lighter with
a new nanotube-based outer conductor developed by Rice University scientists.
The Rice lab of Professor Matteo Pasquali has developed a
coating that could replace the tin-coated copper braid that transmits the
signal and shields the cable from electromagnetic interference. The metal braid
is the heaviest component in modern coaxial data cables.
The research appears this month in the American Chemical
Society journal ACS Applied Materials and Interfaces.
Replacing the outer conductor with Rice’s flexible,
high-performance coating would benefit airplanes and spacecraft, in which the
weight and strength of data-carrying cables are significant factors in
performance.
A coating of
carbon nanotubes, seen through a clear jacket, replaces a braided metal outer
conductor in an
otherwise standard coaxial data cable. Rice University scientists designed
the cable to save
weight for aerospace applications. (Credit: Jeff Fitlow/Rice University)
Rice research scientist Francesca Mirri, lead author of the
paper, made three versions of the new cable by varying the carbon-nanotube
thickness of the coating. She found that the thickest, about 90 microns –
approximately the width of the average human hair – met military-grade
standards for shielding and was also the most robust; it handled 10,000 bending
cycles with no detrimental effect on the cable performance.
“Current coaxial cables have to use a thick metal braid to
meet the mechanical requirements and appropriate conductance,” Mirri said. “Our
cable meets military standards, but we’re able to supply the strength and
flexibility without the bulk.”
Coaxial cables consist of four elements: a conductive copper
core, an electrically insulating polymer sheath, an outer conductor and a
polymer jacket. The Rice lab replaced only the outer conductor by coating
sheathed cores with a solution of carbon nanotubes in chlorosulfonic acid.
Compared with earlier attempts to use carbon nanotubes in cables, this method
yields a more uniform conductor and has higher throughput, Pasquali said. “This
is one of the few cases where you can have your cake and eat it, too,” he said.
“We obtained better processing and improved performance.”