Washington, April 28 Imagine creating vehicles as tiny as a molecule, billions of which could fit into a millimetre and be powered by sugar.

The concept is nearly unthinkable, but it's exactly the kind of thing occupying National Science Foundation (NSF) supported researchers at Penn State and Rice University.

For several years, Ayusman Sen, who heads Penn State's department of chemistry, and his colleague Thomas E. Mallouk, director of the Centre for Nanoscale Science, have investigated technologies that could realise these remarkable machines.

Their uses might include drug delivery to specific tissues, accomplishing surgeries and communicating with the outside world from inside the human body.

Though researchers consistently have improved ways to build nano-machines, the stumbling block has been finding a way to power them.

Shrinking energy producers -- internal combustion engines, electric motors or jet engines -- below millimetre dimensions is not an easy task, but researchers may be closer to a fantastic solution.

Today, researchers can steer nano-machines, use them to convey cargo, and guide them using electromagnetic forces or chemical interactions. All of this, they say, makes the world seen in the 1966 movie 'Fantastic Voyage' not so far-fetched, said a Penn State release.

These findings are slated for publication in the May 9 issue of Scientific American.

Ayusman Sen did his M.Sc. from the Indian Institute of Technology, Kanpur in 1973 and Ph.D. from the University of Chicago in 1978. He is also the recipient of the National Science Talent Search Scholarship, India from 1967 to 1974.