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.