Tien Nguyen: This is a tiny microrobot fighting
its way against blood flowing in an artificial
vein.
The scientists who designed these bots imagine
them cruising the bloodstream, carrying cancer-killing
drugs to treat difficult-to-reach tumors deep
inside the body.
This approach to drug delivery would minimize
the exposure of normal, healthy cells to toxic
chemotherapy drugs, thus avoiding side effects.
So says Metin Sitti, who helped to create
the bots.
Metin Sitti: Our goal of using microrobotic
approach is to localize the cancer drugs to
only tumor regions so there is no side effects.
Tien Nguyen: The team calls these bots “microrollers”
because they navigate blood vessels
by rolling along their walls.
By sticking to the walls where blood flow
is slower with the help of a magnetic field,
the microrollers can roll against the bloodstream,
which has been a challenge for bots of this size.
The microrollers have two faces, each with
a specific job.
One side is needed for navigation and it’s
made of magnetic gold and nickel layers.
This face allows researchers to control the
microbot’s movements by flipping on a weak
external magnetic field.
By changing the direction of the magnetic
field, the team can change the direction of
the bots’ movements, with speeds up to 
600 μm/s.
The researchers could even steer the bots
through junctions, like those the microrollers
would encounter in an actual circulatory system.
The other face of the bots is critical for
attacking tumors.
This face is equipped with antibodies and
cancer drug molecules.
The antibodies bind to proteins found specifically
on breast cancer cells.
This allows the bots to stick to the tumor
cells while passing by healthy skin cells
shown at the bottom of the screen.
Once the bots reach a tumor, researchers could
zap them with UV light to trigger a chemical
reaction that releases the cancer drug payload.
But prolonged UV exposure can damage healthy
cells, so Sitti says his team is working on
other ways to release the drug such as using
a change in temperature.
