"They're everywhere. The average American home has 50, the car more than 100," says Rod MacGregor, who's talking about miniature motors that move everything from CD-player platters to the power mirrors in an SUV. MacGregor, a computer scientist and president of Nanomuscle in Antioch, California, thinks their day is past. He wants to replace them with a musclelike actuator that is smaller, silent, and cheap. Nanomuscle's device contains wires made of shape-memory alloys that shrink in response to electrical heating. In the past such alloys were slow and moved in unpredictable ways. MacGregor's team figured out how to get more usable motion by attaching multiple alloy strands to a stack of metal plates and by regulating each strand so that the stack moves the same way every time. The mechanical muscle is the size of a paper clip and consumes one-fifth as much power as a motor of the same size and strength. The first nanomuscles should show up in toys later this year and in cars soon after.
An artificial-muscle walking toy.Photographs courtesy of Nanomuscle