A way of making a thread purely from carbon nanotubes has been developed by researchers in China. They say the super-strong, electrically-conducting threads “should eventually be able to be woven into objects such as bullet-proof clothing and materials that block electromagnetic waves”.
Existing methods of creating the threads involve mixing carbon nanotubes with an adhesive substance. This makes better-bonded threads, but reduces their strength and conductivity. Kaili Jiang and colleagues, at Tsinghua University, made the new fibre by growing carbon nanotubes in alignment on a silicon substrate. They then drew a thread from the substrate in a process similar to spinning thread from a silk cocoon.
The team produced a thread 30 centimetres long and 200 microns thick. They estimate that one cubic centimetres of raw nanotubes could produce up to 10 metres of thread.
In further experiments, the researchers showed that applying a voltage to the thread can “weld” curves or joints into place. Applying the voltage was also found to improve the conductivity of the material.
“As a start, it’s pretty spectacular,” says Cees Dekker, an expert in carbon nanotubes at Delft University of Technology in the Netherlands.
Philippe Poulin, at the Paul Pascal Research Center in France, is working on threads generated by bonding carbon nanotubes and a soluble adhesive. He told New Scientist: “The important thing is that the Chinese team can produce more pure fibre.”
Poulin speculates that the fibre produced by the Chinese team will have good electronic properties, but will be less strong. But he remains optimistic about the potential of carbon nanotube thread, saying materials made from the threads could be available in the next few years.
He also says the thread could one day be used to build microscopic devices, because applying an electrical charge can cause the thread to move with significant force.
“You can generate forces that are 100 times that of a human muscle with the same mass,” Poulin says. “The bad news is that currently it doesn’t last very long.”