"I can make hundreds of thousands as easily as I can make one," said lead nanotechnology researcher Carlo Montemagno of the University of California, Los Angeles.

Montemagno is the co-author of a paper on the break-through microbot in a recent issue of the journal Nature Materials.

The accomplishment is distinctly different from other research, where muscle tissues were arduously excised from living frogs or other animals, painstakingly attached to mechanical apparatuses and made to contract and relax.

Montemagno and his team etched nanometer-scale lever arms into silicon chips then, without using chemicals that would kill cells, spanned the spaces from the lever arm's handle to an anchor point with a chrome/gold ribbon.

Finally, they added rat pup heart cells to the chips, which only stuck to the metal ribbon, and immersed it all in a sugary solution. The muscle cells divided and grew along the ribbon to create tiny muscles that can be stimulated to pull the levers.

"It's really a phenomenal thing," said George Bachand, a nanotech biologist at Sandia National Laboratory and a former collaborator with Montemagno. "It's really a fully integrated system," he said of the blend of biological and mechanical parts.

That blend opens up enticing possibilities in prosthetics, among other fields, Bachand said.

"Now we implant things that are entirely artificial," Bachand said.

In the future, Bachand suspects the technology could be used to rebuild severed fingers, for instance, by growing new muscles from a patient's own muscles cells onto artificial bones.

There is also the very practical matter of learning more about muscle tissues. By growing them and making the new muscles perform very specific and measurable tasks, physiology researchers can learn a lot about the workings of different muscles tissues.

The success with muscles also opens the possibility that other types of cells and tissues can be incorporated into microchips, said Montemagno, for a multitude of other tests and uses.