Ultrasmall machines are everywhere these days. Tiny mechanical devices, so minute that a hundred thousand could sit on a pencil eraser, are responsible for triggering your airbags during an accident, spitting colors out in precise detail on your inkjet printer and projecting light in the newest digital theaters. Made with the same silicon fabrication methods used to crank out computer chips, microelectromechanical systems (or MEMS) have over the last decade become well embedded in the high-tech landscape.

Now engineers and physicists are taking the next step in machine miniaturization, building mechanical devices on the nanometer scale (a billionth of a meter). If the researchers succeed, their work could lead to ultrasensitive sensors that can detect even the most subtle genetic alterations responsible for a disease, or to ultrastrong artificial muscles that might replace damaged human tissue or power tiny robots.