WASHINGTON -- Researchers said Thursday they had created the smallest pen, and said its tiny nub could be used to "write" microscopic electronic circuits.

They used their instrument to inscribe extremely fine lines, just a few molecules thick, onto gold.Writing in the journal Science, the team at Northwestern University in Chicago predicted that their method, which they called dip-pen nanolithography, could be used in microfabrication, nanotechnology, and molecular electronics.

"This should open up many ways to explore the nano-world of electronics based on molecules," Chad Mirkin, a chemistry professor at Northwestern who directed the study, said in a statement.

The device works on the same principle as an old-fashioned quill pen. But its "ink" is made from chemicals known as alkanethiols, and the "paper" is gold.

The "pen" is an atomic force microscope, or AFM, which is often used in laboratories working on tiny devices.

"It's engineering, but when you get down to the 'nano' scale, it's really chemistry," Mirkin said.

He would like to perfect the pen so that it works more like a fountain pen, saving the need to continually dip into the "ink."

He sees immediate uses, for instance, on nanochips used in computers.

"Suppose I have a computer chip that will form the basis for a chemical sensor, and I need to put onto its nanocomponents some chemical that will tell me whether or not some chemical agents are around," he said.

"I could use this type of technique to do that. I can go in and just paint those components with different types of molecules."