The development is viewed as a step towards building tiny `machines' that could, in future, perform intricate tasks like building computer circuits and clearing clogged blood vessels in the brain, the science journal Nature reports.

``The hinge-like part bends on cue. It is incredibly small -- four by 10,000th of the width of a human hair, it said.

Unlike earlier attempts in `nanotechnology,' the new device is said to be particularly rigid and executes motions ten times bigger than before, the report said.

However, K Eric Drexler of the Institute for Molecular Manufacturing in Los Altos, California, said that the device is too cumbersome to be useful now but further development may lead to a practical device.