Micro-machine tool developed

A micro-structure etched into a silicon wafer

By BBC News Online science editor Dr David Whitehouse

German scientists have developed a simple electrochemical way of making tiny three-dimensional structures.

Many scientists believe that miniature machines could find many applications in medicine and sensor technology. But the fabrication of very small parts - about a thousandth of a millimetre - is still a challenge.

A fly's eye and a micro-fabricated structure

Using a minute electrode, the scientists from the Fritz Haber Institute in Berlin electrochemically etched a workpiece with microscopic precision.

The new technique uses ultra-short pulses of electricity between electrodes - the pulses last just a billionth of a second.

Copper and silicon

The very brief duration means the etching of the material is confined to very small areas near the electrode. This allows intricate and precise shape to be cut.

The procedure has already been demonstrated using copper and silicon. Other materials, such as alloys, may also be easily structured with high precision.

Scientists say that the positioning of the tool electrode close to the surface to be sculpted is at the heart of the new method.

A cylindrical tool electrode is used, which works like a grinder on a probe. Moving the tool through the workpiece enables the fabrication of three-dimensional structures.

The research is published in the journal Science.