Artificial muscles developed at Auckland Bioengineering Institute's Biomimetics Lab in New Zealand have been used to power a small motor.
(Artificial Muscles Power A Motor video)
The muscles themselves are electroactive structures consisting of two layers of conducting carbon grease separated by an extremely stretchy insulating polymer film, says Anderson. "It can stretch by more than 300 per cent."
When a voltage is applied, the configuration behaves like a capacitor, with positive and negative charges accumulating on either side of the insulator. As the opposite charges attract one another the insulator is squashed between them and flattens and stretches. Turn the voltage off and it contracts again to its original size.
The motor looks rather like a bicycle wheel, with the elastic muscles stretched between the edge of the wheel and the centre, like flat spokes. To turn a shaft, six of the muscles work in concert, contracting one after the other. Although the device looks as if it is wobbling like jelly, the spokes are connected to a foam ring wrapped tightly around the central shaft, and this arrangement exerts a continuous rotational force.
This device reminds me of the power-wagons from Jack Vances The Last Castle:
Power-wagons, like the Meks, originally swamp-creatures from Etamin 9, were great rectangular slabs of muscle, slung into a rectangular frame and protected from sunlight, insects and rodents by a synthetic pelt. Syrup sacs communicated with their digestive apparatus, wires led to motor nodes in the rudimentary brain. The muscles were clamped to rocker arms which actuated rotors and drive wheels.
(Read more about Vance's power-wagon)
Update 19-Oct-2011: Martin Caidin specifically uses this term in his 1972 novel Cyborg, which was the basis for the film Six Million Dollar Man; see the entry for artificial muscles. End update.