Tiny Robots Flex Their Plastic Muscles

By BBC News Online science editor Dr David Whitehouse

June 29, 2000

Miniscule submersible robots may soon cruise through your
bloodstream looking for misbehaving cells or even man the
production lines of miniature factories.

Swedish researchers have made crude micro-robots that are
shorter than this hyphen - and no wider than the full stop
at the end of this sentence.

Unlike many previous designs, the robots can function in
different kinds of liquid, such as blood, urine, and the
media used to culture cells. This could make them very
useful to biotechnologists.

"Being able to manipulate many individual cells at the same
time is becoming increasingly important in many areas of
science," says Edwin Jager, of Sweden's Linköpings
Universitet, lead author of a paper on the robots which
appears in the journal Science.

"We think that these micro-robots would be helpful for
fundamental studies, or for manufacturing other small
devices, especially if we set up arrays of them."

Shrink And Swell

The Swedish team speculate that the robots' miniature hands
might someday pick up single cells or bacteria and transfer
them to analysis stations.

The micro-robots have a silicon framework encased in layers
of gold and a conducting polymer, such as polypyrrole.

The polymer can be forced to shrink and swell by subjecting
it to spurts of positive and negative ions. This makes
segments of the robot bend.

And by carefully controlling which particular segements bend
and when, the researchers can simulate the action in their
robots of elbows, wrists, hands, and even fingers.

Previous micro-robots have included electronic devices
featuring rods and levers, artificial wings and legs. But,
"none of these operate in water, and would not be suitable
for the manipulation of cells," Jager says.

'Factory Workers'

Submerged in an electrolyte solution, several robots were
wired to an electrical source and videotaped as they hoisted
glass beads.

By stimulating the micro-robots' fingers, wrists and elbows,
the researchers made their mini-machines move the beads a
distance 0.25 millimetres (0.01 inches).

The robots also managed to transfer the beads from one
miniature conveyor belt or "track" to another, proving their
potential as tiny factory workers.

The scientists say that if treated with adhesion molecules,
the robot's fingers might select particular cells or
bacteria from a sample.

The micro-robots could be positioned at the end of a
catheter to assist surgical procedures.

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