Here’s a question for makers of minuscule moving machines—the kind being eyed for nanomanufacturing and assembly as well as other uses: Do you know where your micro- and nanorobots really are? Care to bet?

A team of researchers at the National Institute of Standards and Technology (NIST) would likely prevail in such a hypothetical wager. On the basis of its surprising findings in an exacting study of the motions of an experimental microelectromechanical system (MEMS), the team might even offer better-than-even odds.

The group tracked, for the first time, the step-by-step motion of a standard type MEMS device called a “scratch drive actuator,” a micromachine (120 µm wide, 50 µm long, and 1.5 µm thick) that drags itself over a surface by repeatedly flexing and relaxing a tiny hooked arm. Using a novel measurement method adapted from single-molecule biophysics research, the researchers tracked and measured each of the device’s 500 steps along a 20-µm path. They found that the incremental movements varied significantly, from just a few nanometers (nm) to almost 100 nm.

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