MORE AGILE AND SMARTER TOOLS TO COME
Minimally invasive “keyhole-like” robotic surgeries will continue to
make strides with even greater agility. The payoff will be shorter patient
hospital stays, more accurate and effective procedures, and lower risks
(e.g., infections) thanks to smaller surgical openings and faster procedures.
For example, Japan’s Tokyo Institute of Technology is investigating
an approach that allows the assembly of robotic components within
the body, prior to surgery, to assist in robotic surgeries on large and
slippery internal organs like the liver.
These researchers are developing a three-fingered steel hand, with
each finger 5 cm long, for grasping internal organs. They’re using a
hollow arm, 30 cm long and 16
mm in diameter, that’s inserted
into the body via a small
incision. The three fingers are
then passed part of the way
through a nearby keyhole and
then snapped into place on
the arm. Stiff wires along the
arm allow the fingers to grasp
organs. Experiments inside a
dummy body cavity have shown
this approach to be effective.
At Johns Hopkins University,
researchers hope to soon unveil
advanced robotic grippers and
retractors with force sensors for
human trial runs. These tools will
allow surgeons to avoid gripping blood
vessels too tightly. Additionally, they
will allow oxygen sensors to differentiate
diseased tissue from healthy tissue. One
tool flexes much like an elephant trunk to
glide down a patient’s throat for scar-less
repairs of the upper airways. Another tool
that’s now under development will let
surgeons bust eye clots inside minuscule
blood vessels.
Robotic snake-like tools are under
development at the Imperial College
of London and Carnegie Mellon
University. The Imperial College’s
i-Snake project, a $4.2 million program
funded by the Wellcome Trust,
a large U.K. charity that funds innovative
biomedical research, centers
on a flexible robotic arm that acts
as a surgeon’s hands and eyes.
The technology will permit surgeons
to navigate difficult and restrictive
regions of the body, such as the
alimentary tract and cardiovascular
pathways, faster and more precisely
than they could while using conventional
techniques.
Carnegie Mellon’s miniature
HeartLander facilitates minimally
invasive therapy on the surface of
the beating heart (Fig. 5). Under
physician control, the robot enters
the chest through an incision below
the sternum and adheres to the
epicardial surface of the heart. It
then autonomously navigates to
the specified location and administers
the treatment. Compared
with existing approaches, it
improves the precision and stability
of interaction with the heart’s
surface while decreasing the
morbidity associated with
access.
One of the greatest challenges
lies in developing a
robotic system that works
in a magnetic-resonance
imaging (MRI) environment
where surgery is being performed.
MRIs have strong
and sensitive magnetic fields
that must be bypassed.
Otherwise, the MRI image
will be distorted. The Johns
Hopkins PneuStep, a robotic
tool that’s designed for prostate
surgery, alleviates these MRI
problems.
PneuStep consists of six motors
that power an MRI-compatible robot. Three pistons are connected to a series
of gears. The gears are turned by air
flow, which is in turn controlled by a
computer located in a room adjacent
to the MRI machine. The system can
achieve precise and smooth motion up
to 50 µm, finer than a human hair and
well above that of a human surgeon.
PneuStep is currently undergoing preclinical
trials.
The neuroArm is another MRI-compatible
robotic tool being developed at Canada’s
University of Calgary. This machine can provide
precision motions up to 25 µm. It uses
lead-zirconium-titanate (PZT) motors to move
a small ceramic finger back and forth. The
finger rotates a ceramic ring, creating motion
through friction.
In the near term, cost will limit the widespread
adoption of full-fledged large robotic surgical
systems, which can go for $1 million or
more and are expensive to maintain. Yet studies
reveal that most surgeons who used such
systems have become converts to this technology.
Clearly, lower-cost systems are needed,
and many researchers worldwide are busy working
to reach that goal.