several fundamental challenges. “Such
bacteria-propelled nanobots are limited by the stochastic nature of cellular
motion, and by the relatively brief lifetimes of bacteria,” he says. In addition,
Sitti says he and his team must develop
more effective ways to communicate
with nanobots once they are inside a
body. “Methods must be found to program and control large numbers of
nanobots,” Sitti says. “This will be necessary if such devices are to treat large
areas of the body, to increase the speed
and success of medical operations, and
to deliver sufficient amounts of drugs
to their targets.”
Scientists working in this area say
the nanorobotic systems developed
by Martel, Sitti, and other researchers
could lead to new surgical techniques
far more sophisticated and far less invasive than methods currently in use.
Such techniques would rely on devices
capable of entering the human body
through natural orifices or very small
incisions to perform diagnostic procedures or repair tissue. “The mechanisms of life operate at the nanoscale,”
says Aristides Requicha, director of the
laboratory for molecular robotics at the
University of Southern California. “If we
build devices at their scale, we will be
able to interact intimately with them.”
One goal of Requicha’s work in this
area is to overturn the basic paradigm
of today’s medicine, and to shift from a
treatment model to a prevention model
through the use of in-body sensors that
check for and kill pathogens before the
patient has any symptoms. Essentially,
Requicha’s vision entails rethinking
the traditional sequence of patients
demonstrating symptoms and then
seeking medical care for their ills. “In
the long run,” he says, “I would like to
build artificial and preferably programmable cells.” In the meantime, though,
one project Requicha and his team are
working on is a network of wireless
nanosensors capable of operating in
biological environments. “This network would give us unprecedented capabilities to study cell biology by being
able to acquire data in real time and for
extended periods,” he says.
Near-Term applications
While some research in this field remains theoretical and might never directly lead to real-world applications,
aristides Requicha’s
research aims for
a preventive health
model in which
in-body sensors
check for and kill
pathogens before a
patient exhibits
any symptoms.
several nanorobotics labs focus specifically on projects that might have
near-term practical applications. “One
aspect of entering these fields that was
particularly important to me, as an engineer, was to make sure there were
genuine applications on the horizon
that made sense,” says Bradley Nelson,
head of the institute of robotics and
intelligent systems at ETH Zürich. “It
rapidly became clear that applications
in biological research were possible,
but then it became even more clear
that the potential in medicine was the
real reason for pursing these fields.”
Among many projects, Nelson’s
group is creating artificial flagella designed to mimic natural bacteria in
both size and swimming technique and
is working on nanobots for retinal surgery. The challenges he and his team
face, as with other researchers working
in this area, are numerous. Still, Nelson
says he remains optimistic, and points
to a recent spinoff called Femto Tools,
in Zürich, Switzerland, that is already
marketing micromanipulation products, such as force sensors and micro-grippers. “With sufficient resources
and energy and the backing of doctors
and business people,” he says, “retinal
therapies using nanobots will be possible within five years.”
With nanorobotics labs working
hard to address fundamental issues in
physics, biology, and computer science
as they seek to create viable medical
applications, at least one major challenge resides on a more social level.
One of the most frequently cited difficulties of working in this field is the
interdisciplinary nature of the research
itself, which requires not only combining advanced science in health with advanced science in robotics, but also the
ability to communicate in the language
that medical professionals use.
Nelson’s group, for example, consists of roboticists, mechanical engineers, electrical engineers, software
engineers, computer vision researchers, materials scientists, and chemists. And the team works directly with
doctors and biologists. “Trying to understand what all these disciplines are
about and how they can work together
is a major challenge and, to me, one of
the most stimulating aspects of this
field,” Nelson says. Martel points to a
similar experience. “In my office, I can
talk about a new imaging algorithm on
an MRI machine, and five minutes later
have a conversation about microelectronic circuits, antibodies to connect
nanoparticles to miniature robots, or
genetics to enhance the molecular motor of flagellated bacteria,” he says.
Requicha, for his part, says interdisciplinary work is exciting but not
easy. “This is an issue not only at the
research level, but also educationally,”
he says. “How do we prepare students
to work in this field?”
In addition to the challenges associated with the interdisciplinary nature
of the research, researchers cite safety
issues, health concerns, and government regulation as other key issues.
Swallowing or injecting miniature robots is not something many patients
would readily agree to do without assurances of safety, or at least some demonstrable evidence that the potential
benefits outweigh the possible risks.
Because human physiology is complex,
dynamic, and even different from person to person, reliably producing such
evidence likely will remain an engineering challenge for years to come.
Despite the many challenges, researchers say the efforts will yield positive results in the end, with technology
that revolutionizes medicine by making health care less expensive and less
painful, and enabling medical professionals to target diseases for diagnosis
and treatment, precisely and locally.
Based in Los Angeles, Kirk L. Kroeker is a freelance
editor and writer specializing in science and technology.