The development could set the stage for a new generation of microscopic devices that can track bacteria, sniff out chemicals, destroy pollutants, conduct microsurgery and scrub the plaque out of arteries.

Although microscopic machines have already been designed to crawl, swim, walk and fold themselves up, there were always 'strings' attached; to generate motion, wires were used to provide electrical current or laser beams had to be focused directly onto specific locations on the robots.

"Before, we literally had to manipulate these 'strings' in order to get any kind of response from the robot," said Itai Cohen, professor of physics. "But now that we have these brains on board, it's like taking the strings off the marionette. It's like when Pinocchio gains consciousness."

The 'brain' in the new robots is a complementary metal-oxide-semiconductor (CMOS) clock circuit that contains a thousand transistors, plus...