| WASHINGTON (AP) - Robots the size of the punctuation in this sentence could one day be used to move single cells or capture bacteria, their Swedish inventors say.
The tiny robots are shorter than a hyphen and no wider than the period at the end of
this sentence, according to Edwin W. H. Jager of Sweden's Linkoping University.
The robots might be used as microsurgical instruments, explained Jager. ''Maybe not (in
the same) shape and form of these robots, but tools using the same micromuscle
technology.''
Or, he added, these microrobots might be used to build other microdevices, just as cars
are built by robots. In medicine, the robots could move a single cell from one point to
another, he said.
In experiments his team has used the robots to pick up and move tiny glass beads invisible
to the unaided eye.
Their work is reported in Friday's issue of the journal Science.
The microrobots are made of layers of polymer and gold and somewhat resemble a human arm.
Currently they remain in one spot, but Jager said he could foresee a time when they are
made mobile.
The robots have flexible elbow and wrist joints and the research team made them in various
forms with hands made up of two to four fingers.
Importantly, Jager noted, these devices can work while submerged in such liquids as blood,
urine and cell-culture medium, suggesting possible uses in biotechnology. Stuck on the end
of a catheter, the microrobots might increase the range of surgeons.
Jager's co-authors, Olle Inganas and Ingemar Lundstrom, said in a statement that one day
the robots might be usable to pick up tiny biological items and move them to an analysis
station, and in groups to assemble microstructures.
To make the microrobots move, the team used conducting polymers in the joints. These
polymers will absorb charged particles called ions from the surrounding liquid, or shed
them, depending on the electrical charge applied through tiny wires connected to the
robot. Absorbing or shedding ions causes the polymers to swell or shrink, while the gold
layer remains the same thickness.
By properly arranging the polymers and gold layers the swelling or shrinking of the robot
joints causes them to bend when various charges are applied, similar to changes in heat
causing the movement of a thermostat.
Bending of the polymer-gold layers causes the robot arm to flex at its elbow, bend the
wrist and close and open the fingers to grasp it.
Previous microrobots have included such things as electronic devices featuring rods and
levers, artificial flying insects and a walking silicon microrobot, but none could operate
in water, Jager pointed out.
His microrobots are 670 millionths of a meter tall and 170 to 240 millionths of a meter
wide.
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Chapter: Medical Forum