the tissue, providing valuable feedback
for the surgeons performing the Foker
technique today, who rely largely on empirical training. This data is transferred
via cable to a microcontroller in a small
external vest, which then transmits it to
a laptop via Bluetooth. In an animal experiment, the robot coaxed the esophagus into growing 77% over nine days.
On the Move
While Damian’s device remains in
place for long-term therapies, researchers developing miniature machines
have more mobile robots in mind.
While the engineering obstacles are
significant, the infection risks could be
lower, since miniature or micro-robots
could be swallowed as pills or inserted
via tiny incisions.
Unlike the sci-fi movie versions,
however, these tiny machines will not
necessarily rely on miniaturized macroscopic technology. “We can’t just
shrink big robots,” says Diller. “Below
one centimeter, there are some fun-
IN 2013, UNIVERSITY of Shef- fieldroboticist Dana Damian was doing postdoctoral re- search at Harvard Medical School affiliate Boston Children’s Hospital when she learned of
a procedure called the Foker technique. The surgery, performed on
children with a rare congenital lung
defect, calls for doctors to attach sutures to part of an infant’s esophagus, then tie them off on the baby’s
back. Over time, the sutures lengthen the esophagus by pulling on it,
stimulating tissue growth.
Although the technique can be ef-
fective, the risk of infection and com-
plication is high, and the baby must
remain under sedation for weeks. “We
were surprised that this was the state
of the art at the best pediatric hospital
in the U.S.,” Damian recalls. She and
her team set out to build a less-inva-
sive alternative. “We built a robot that
basically does the same thing.”
The device, developed with col-
leagues at Boston Children’s Hos-
pital and Harvard Medical School,
is 10 centimeters long and contains
a battery, a motor, sensors, and wir-
ing that connects to an external vest.
The machine has the same goal as
the Foker technique, but stimulates
growth by gradually pulling a tissue
segment, while monitoring and con-
trolling the forces applied, leading to
The group’s implant is one example of a growing number of robots
researchers are designing to carry out
medical tasks on, and in, humans.
As a cylinder 10cm long and 3cm
wide, Damian’s robot is relatively
large. Other scientists are working
on robots small enough to swallow.
Eventually, these miniature medical
machines could deliver drugs to specific locations, treat wounds, inspect
hard-to-reach parts of the body, and
even perform simple surgeries.
In classic movies such as 1966’s Fan-
tastic Voyage or the 1987 film Inner
Space, miniaturized robots and ex-
ploratory craft cruise through the
body like high-powered submarines.
Roboticist Eric Diller of the University
of Toronto often shows his students
the latter film to highlight some of
the difficulties of building machines
at this scale. The environment, for
one, is far more challenging than it
seems on screen. For example, add-
ing propellers to a miniaturized robot,
as in the movies, would not allow it to
navigate the bloodstream; the speed
of flow is too high, and to a miniature
robot, Diller says the medium would
seem more like honey than water.
Implanted in the esophagus, the
robot developed by Damian and her
group consists of concentric rings that
promote tissue growth by expanding or
moving apart from each other. A mo-
tor drives the expansion and sensors
measure how much force is applied to
Scientists are developing tiny medical machines
that stretch the definition of the term “robot.”
Technology | DOI: 10.1145/3237123 Gregory Mone
This tiny transforming robot can take on different forms, as needed.