It would be a million times bigger than the ultimate goal, but it would do much to prove that the goal is attainable.

Researchers are building a prototype millimetre-size robot — called a “millibot” — to test the feasibility of nanometer-size machines.

“We started thinking very seriously about building very, very tiny computer control structures for tiny, tiny machines, with the idea that materials broadly could have active elements built into them,” James Ellenbogen of Mitre Corporation

Ellenbogen is working on a miniscule robot that would demonstrate control engineering, showing that it is possible to make a computer, legs and wiring work in a coordinated manner.

The robot would be driven by computers small enough to fit on a single human cell. About 400 of them could fit on a grain of salt. More here.