In a Texas laboratory, a toy mechanical arm just the length of an index finger perches, folded up, at the edge of an empty glass bowl. A young man in a lab coat squirts a volatile fluid, methanol, into the bowl. Moments later, the arm jerks and then hesitantly reaches forward. Although clumsy and slow, the gesture is a remarkable one never previously achieved in any lab: The arm moves when parts of its structure contract in response to reactions triggered by local chemical fuel — much as our own limbs do.
The toy arm’s sinews, made of wire, respond to the methanol because they’re coated with a fine film of platinum nanoparticles. This unique design enables the wires both to harness chemical energy and to carry out the motion, says the leader of the project, Ray H. Baughman of the University of Texas at Dallas.
[…]
In a refinement of the approach, the team fashioned the platinum-coated shape-memory wires into a coiled spring that lifted a weight of up to half a kilogram when exposed to methanol.
