New research eases strain on artificial muscle

Australian researchers have created salt-based liquids that improve the performance of artificial muscle by thousands of times.

The development - achieved by groups at Monash University and University of Wollongong - could be used to create textiles that expand and contract, as well as having applications for batteries and solar cells.

It also means simple prosthetics containing artificial muscles could be available within three years.

Prof Doug MacFarlane from Monash's chemistry department and Dr Maria Forsyth of the school of physics and material engineering have worked for five years on ionic liquids; salts that become liquid at room temperature.

Their work, funded by the Australian Research Council, has helped revolutionise the performance of artificial muscles, which operate just like a battery with electrodes and an electrolyte.

But the limited lifespan of the muscles has rendered them unsuitable for use in humans.

"The electrolyte in between the electrodes was, until recently, a relatively simple salt in a solvent," MacFarlane said. "This meant that the expansion and contraction of the muscle did not last for long, it degraded and, ultimately, the electrolyte evaporated away."

By comparison, the ionic liquids developed by MacFarlane and his colleagues do not evaporate away, allowing the indefinite contraction and expansion of the muscles.

He said that until now artificial muscles could maintain only 10 cycles of expansion and contraction. But the latest discovery, published in the international journal Science, enabled that to increase to more than 100,000 cycles.

"In the much longer term you can expect to see artificial muscles and limbs where you can cause whole limbs to move," MacFarlane predicted. "At the moment you can only do that using a motor with gears, cogs and cables."