Laser advance promises micromachines

Baby bull: 3-D and very, very, very wee

Japanese scientists have used a laser to draw the image of a bull the size of a red blood cell.

The three-dimensional object is the smallest sculpture ever created, giving hope for tiny machines that could work cures inside the body.

The bull created by the team at Osaka University in Japan measures 10 micrometres by seven - a micrometre is one-thousandth of a millimetre.

The technology "could be used to create micromachines small enough to run inside blood vessels," said Professor Satoshi Kawata, head of the Laboratory for Scientific Instrumentation and Engineering at Osaka.

Resin trace

According to the scientific journal Nature, the Osaka scientists traced the outline of the bull on transparent plastic resin, using two lasers linked to a computer programme.

The resin only solidified at the exact focal point of the laser beams.

Previously, such miniature sculptures have been achieved by creating two-dimensional outlines, which are then stuck together to form crude three-dimensional forms.

"The result is that you can fabricate real 3D structures rather than two dimensional layer patterns, as in traditional lithography," said Professor Kawata.

Very tiny machines

Micromachines built using this technique could be used to deliver drugs to specific areas of the body.

Tiny sensors could be constructed to measure blood flow and other internal indicators.

As well as the bull, the Osaka team sculpted a tiny spring from resin.

It displayed the same mechanical properties as a normal metal spring, bouncing back when it was stretched and released.