ROBOT insects need strong muscles鈥攋ust as real bugs do. The challenge
is to make artificial muscles move quickly, as they are usually activated by
chemicals. But now researchers in New Mexico say they can make artificial
muscles react faster by using electricity.
Brett Schreyer and his colleagues at the University of New Mexico in
Albuquerque made their synthetic muscles out of polyacrylonitrile (PAN) gel
fibres, which elongate in alkali and contract in acid. The team increased the
conductivity of the muscle by adding graphite fibres. They then connected the
muscle to a battery and placed it in a salt solution, where it acted as one
electrode. A strip of platinum acted as a second electrode.
When the muscle was acting as the cathode, positive ions accumulated near it,
causing it to contract. Switching the polarity, to make the muscle the anode,
attracted negative ions. This raised the local pH, making the fibres
elongate.
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鈥淭he diameter of the muscle would go from the size of a thick pen when
contracted to about the size of a thin pencil when elongated,鈥� says
Schreyer.
Yoseph Bar-Cohen, an expert in artificial muscles at NASA, says the research
brings scientists closer to building robotic creatures that emulate biology.