Dr Yueh-Lin Loo, a researcher at The University of Texas at Austin, USA, has modified a plastic so its ability to carry an electrical current can be altered during manufacturing to meet the needs of future electronic devices.

Loo, an Assistant Professor of Chemical Engineering, used polyaniline. She says the plastic could potentially be used as flexible, inexpensive wiring in applications such as military camouflage that changes colours, fold-able electronic displays and medical sensors.
By combining polyaniline with a chemical that gives it conductivity, the researcher found she could increase the plastic's conductivity one- to six-fold based on the version of the chemical added.

Chemically altered polyaniline has several advantages over the more commonly used metals, like gold and copper, in devices other than computers. For example, previous research by Loo has demonstrated that so-called "doped" polyaniline can be manufactured in solution at room temperatures and without vacuum chambers. Producing metal-based wires requires special manufacturing conditions and expensive metals.

The researcher has also developed a version of polyaniline that features a conductivity 10 times higher than previous samples. However, that level of electrical conductivity is still below that of copper,which is used to produce high-speed interconnections. Loo's team have used the experiment to develop a better under-standing of how the conductive polyaniline works. The researchers have deter-mined how higher-mass versions of polymer acid improve the plastic's conductivity when the two materials are combined. It is believed that the higher mass acids attach to the plastic in longer chains, and induce a less-ordered internal structure (crystallinity) within the plastic.

"Understanding how the structure of this polyaniline material changes when its conductivity changes will be crucial for selecting the right material for different applications," Loo said.

Also the ability of the plastic to change colours depending on its conductivity could be especially useful.