Double-walled nanotube cables could replace traditional wiring

A Rice University lab has made a cable from double-walled carbon nanotubes and used it to power a fluorescent light bulb at standard line voltage.

Highly conductive nanotube-based cables could be just as efficient as traditional metals at a sixth of the weight, said Enrique Barrera, a Rice professor of mechanical engineering and materials science.

They may find use first in applications where weight is a critical factor, such as in aircraft and cars, and in the future could even replace traditional wiring in homes.

The cables developed in the study are spun from nanotubes and can be tied together without losing their conductivity. To increase the conductivity of the cables, the team doped them with iodine and the cables are said to have remained stable. The conductivity-to-weight ratio (specific conductivity) is claimed to be better than in metals, including copper and silver, and is second only to sodium, the metal with the highest specific conductivity.

The work appears this week in the Nature journal Scientific Reports.

Yao Zhao is the new paper’s lead author. He built the demo rig that let him toggle power through the nanocable and replace conventional copper wire in the light-bulb circuit.

According to a statement, Zhao left the bulb burning for days, with no sign of degradation in the nanotube cable. He is also reasonably sure the cable is mechanically robust; tests showed the nanocable to be as strong and tough as metals it would replace, and it worked in a range of temperatures. Zhao also found that tying two pieces of the cable together did not hinder their ability to conduct electricity.

However, spinning billions of nanotubes (supplied by research partner Tsinghua University) into a cable at all is quite a feat, Barrera said.

The chemical processes used to grow and then align nanotubes will ultimately be part of a larger process that begins with raw materials and ends with a steady stream of nanocable, he said.

The next stage would be to make longer, thicker cables that carry higher current while keeping the wire lightweight.

‘We really want to go better than what copper or other metals can offer overall,’ he said.