Ray H. Baughman, a professor of chemistry at the University of Texas at Dallas, has built muscle fibers that power themselves.

One type is a nickel-titanium alloy coated with platinum, which causes the fuel, currently methanol, to react with oxygen, producing heat. The metal shrinks; the muscle flexes. The artificial muscle can apply 100 times as much force as real muscle.

The second artificial muscle, currently less powerful, is made of a sheet of carbon nanotubes. The reaction of fuel and oxygen releases electrical charges that repel each other and cause the nanotube sheet to expand.