Nanotechnology itself seems at a point where practical fallout from blue-sky research is beginning to appear. But as always, the human imagination tends to outrun the capabilities of technology. To hard-core enthusiasts, it's only a short distance to nanobots and atomic-scale fabrication units that could manufacture them en masse. But to those who want to see practical, economically feasible nanostructured systems, the road seems long and full of twists and potholes. MIT is gambling a lot of its talent, and a big chunk of government money, on the premise that nanotech can yield useful products that will benefit not only the military but a wide swath of the public.

A grand challenge for the institute, which has been in operation for about a year, is the fabrication of a combat outfit so futuristic that it may remain in the realm of science fiction. The concept is deliberately ambitious in order to spur the development of a technology infrastructure with wide applications, said Edwin Thomas, the institute's director. "It may be 20 years out, but we want to find out what can be done," he said.

The battle suit would be only a few millimeters thick and would cling to the body like a scuba outfit. A variety of functions would be built into that thin layer at the molecular scale. Personal sensors would monitor the soldier's body while exterior sensors look for threats. A corresponding set of actuators would respond to injury by changing the properties of the material. If bleeding occurred, the fabric would contract at strategic points to apply a tourniquet. A broken leg would instantly get a cast as the fabric around it stiffened.

On the way to the final goal, spin-offs for police, firefighters and emergency medical teams are expected to appear. And with current terrorist trends such as suicide bombers, lightweight casual clothes that are impervious to shrapnel might turn out to be a big fashion item.

Finding a winning combination for the far more complex situations encountered in combat will require a wide-ranging integration of disciplines, something Thomas believes MIT is uniquely equipped to do. Currently, 37 faculty members from eight departments are involved in work on the problem. The dictum that physics and chemistry are indistinguishable at the atomic level only gets amplified in nanoengineering. Once you start building functioning systems at the molecular scale, mechanical, electrical and bioengineering also become indistinguishable from chemistry and physics.

The response capability of active nanostructured clothing would be similar to that of airbags in cars, Thomas said. "There is only a fraction of a second between the detection of an impact and the deployment of the bag. It would have been interesting to sit in on the original design sessions for that-how could you possibly do that?" MEMS accelerometers and explosive charges turned out to be the winning combination, but it was still difficult to sell the auto companies and the public on the concept at the outset.

Airbags are definitely in the macrofabrication range. Likewise, the current systems equipping troops in Iraq for a variety of threats are advanced systems containing electronics, sensors and chemical-warfare deterrents, but each particular function needs a heterogeneous block of different technologies to work. The result can be seen on the evening news as U.S. soldiers trudge through blazing heat in bulky uniforms, laden with equipment. And the integrated, instantaneous response of airbags is missing. If a sensor detects a chemical agent, the soldier must stop, unpack a gas mask and put it on.

Thomas said one army officer lamented that the soldier winds up like a Christmas tree, with all the shiny new systems coming out of research hung on a limited frame. Indeed, Thomas believes the macro, top-down approach to technology development has inherent limits. What's really needed is a millisecond response.

"We don't know at this point whether nanotechnology is really essential to do this, but the project presents a set of really hard problems, and maybe nanotech will do it," he said. It could be that some other, more conventional approach will achieve the same results more easily, but nanotech seems to have the broadest possibilities even beyond the battlefield. It is that broad potential that drives much of the push worldwide to develop this fundamentally new approach to fabrication.

"This is far-out, cool stuff," Thomas said, registering the excitement that the field engenders.

The key to the new nano-fabrics will be a hierarchy of systems that will be fully integrated across many physical scales. The multilevel approach can be seen in a team at the institute that is creating the fabrication techniques needed to realize the individual advances of the other research teams.

With faculty drawn from the chemical, mechanical, electrical and materials sciences, Team 05-which includes Thomas himself (department of materials science and engineering)-has embarked on projects to fabricate nanoscale fibers and films that will be integrated with microfluidic systems. It is also developing low-temperature chemical-vapor deposition systems for polymers and other materials that could be integrated into fabric. One novel project in this group is "nanoscale origami," a technique for folding thin films into three-dimensional structures.

Although only at the starting gate, Team 05 has come up with an electrospin process that has created artificial spider silk with a diameter less than 100 nanometers. It has also created hollow nanofibers that might eventually be filled with smaller-scale structures.

Meanwhile, Team 04, investigating biomaterials and nanodevices for military medicine, has already reported a breakthrough (see story, page 18).

A major theme throughout the project is biomemetics. Nature has found a variety of ways to create the type of multifunction fabric envisioned by the institute. Skin, fur, the exoskeletons of insects and crustaceans, the shells of conchs and other mollusks, and the dendritic skeletons of coral all provide the kind of integrated functionality, organized on the molecular scale, that the researchers seek.

An example of how nature can be enlisted in the nanotech enterprise is provided by the nanowire process devised by Angela Belcher, a specialist in materials science and bioengineering at MIT. Belcher began by analyzing the biomolecular process that the abalone uses to construct its shell. The creature's basic trick is to construct proteins that bind to calcium, which is present in the ocean. The proteins provide the complex structure, and the calcium offers rigidity.

Belcher began to look at similar processes that would involve semiconductor or polymer materials of interest to the institute, along with fast-growth organisms that could be the engine for quick assembly of complex structures on the molecular scale. She found a specific bacteriophage had a similar ability to bind the proteins in its shell to semiconducting materials and set up a growth process that caused the virus to build nanowires. The process could be modified to produce nanoscale fibers and devices that could be integrated into a functional fabric.

Beyond simple nanowires, the biological-engine approach might produce sensors, actuators and other devices needed to give functionality to the fabric, the MIT group believes. And this is only one of a wide variety of both organic and inorganic approaches to nanofabrication. Currently the project is organized into seven teams. Besides Teams 04 and 05, the other groups are investigating energy-absorbing materials; mechanically active materials and devices; sensors and chemical/biological protection; modeling and simulation of materials and processes; and integration and transitioning of technology systems.

Preliminary results are flowing out of the group projects. Putting it all together into a functioning system that solves problems will be the grand challenge.