Molecular manufacturing promises to change the way many products are assembled.

Billions of dollars are being poured into nanotechnology-the science of building devices at the scale of individual molecules. Because it promises to revolutionize many industries, ranging from automotive to aerospace and consumer products to medical devices, commercial nanotech applications appear to be endless. And, after several years of hype and hoopla, nanotech-based products are starting to emerge from laboratories and R&D centers.

Nanotechnology is the science of manipulating atoms and molecules to fabricate materials, devices and systems. Unlike current production methods, in which existing parts and components are combined, nanotechnology takes individual atoms and precisely assembles them to produce items with desirable characteristics. Objects are built in a manner similar to the way bricks are stacked on top of one another to build a wall.

According to Dave Bishop, vice president of nanotechnology research at Lucent Technologies' Bell Labs (Murray Hill, NJ), nanotechnology deals with things whose length scale is "bigger than an atom, but smaller than a human red blood cell." The typical human red blood cell is about 10 microns in diameter-that's a tenth of the diameter of a human hair. One nanometer is one-billionth of a meter, which is approximately the width of 10 hydrogen atoms.

Many observers believe nanotechnology is the next logical step in miniaturization and that it is only a matter of time before the impact is felt in many industries. As a result, investment bankers and venture capitalists are jumping at the chance to profit from numerous start-ups and joint ventures.

"We believe nanotechnology could be the next growth innovation, similar in importance to information technology over the past 50 years" says Steven Milunovich, global technology strategist at Merrill Lynch & Co. (New York). "Nanotech is real-the questions generally are when, not if."

"Building at the nano-scale enables new interactions in materials, semiconductors and biological agents," adds Milunovich. "The new scale allows manipulation on the cellular level, which should enable new discoveries in pharmaceuticals, biodefense and many health care industries."

"Like the Internet, nanotechnology risks being overhyped," warns Milunovich. However, he says there is a significant difference between the Internet and nanotechnology. "Unlike the Internet, significant intellectual property and patents are barriers to entry, and yet barriers to adoption are low," explains Milunovich.

More than 1,500 companies worldwide have announced nanotech R&D plans. Lux Research Inc. (New York) predicts that $8.6 billion will be spent on research in 2004. But, this year marks a turning point for the field of nanotechnology. It will be "the last year that governments outspend corporations on nanotechnology," claims Mark Modzelewski, managing director of Lux Research. "This year, governments will pour $4.6 billion into nanotechnology research, while corporations will sink in $3.8 billion globally. Smaller amounts will come from universities and other sources."

Tiny Technology, Big Applications

While most nanotech firms are small startups, traditional manufacturing heavyweights such as General Electric Co. (GE, Fairfield, CT), General Motors Corp. (GM, Detroit) and Lucent Technologies are pouring vast resources into the field.

General Motors is currently using nanocomposites to build lighter, stronger running boards for the GMC Safari van, cargo beds for the Hummer H2 sport utility vehicle and exterior panels for the Chevrolet Impala sedan. According to Alan Taub, executive director of GM's Research and Development Science Labs (Warren, MI), nanocomposites are stiffer and lighter than traditional thermoplastic olefins, and less brittle in cold temperatures. In addition, they are more recyclable because there is less additive material. And, no new tooling is required to mold or assemble the parts.

The 2004 Chevrolet Impala, GM's highest volume car, features body side moldings made with nanocomposites that provide a 7 percent weight savings and improved surface quality. The 2005 H2 SUT cargo bed uses 7 pounds of molded-in color nanocomposite parts for its trim, center bridge, sail panel and box rail protector. "We designed this vehicle to use the nanocomposite parts because they are lightweight, and they don't change shape when subjected to temperature changes, which enhances the overall quality of the vehicle," says Bill Knapp, H2 program engineering manager.

Taub claims that GM currently uses 660,000 pounds of nanocomposite material per year, which is the highest volume of olefin-based nanocomposite material used in the world. Like other thermoplastics, nanocomposites are made by introducing a solid material into a plastic resin to give it added strength. Taub says GM's nanocomposites achieve a unique combination of strength and flexibility by altering the molecules of a clay so that they cling to an oil, which they wouldn't otherwise do. The company's researchers have devised a way to peel apart very thin flakes of the clay, similar to the way pages are separated in a book. Compared to conventional fillers, the size of the nanofiller is on the molecular scale, a thickness of one-billionth of a meter, or about 1/100,000 the width of a human hair.

"The virtue of using a nanocomposite for automotive applications is that less filler material is required to provide the same or better performance characteristics when compared to conventional materials," says Will Rodgers, a GM staff scientist. "Our next applications for nanocomposite materials will be in exterior claddings, interior parts and nonsupport trim."

Scientists at the GE Global Research Center (Niskayuna, NY) have filed numerous nanotech-related patent applications. Margaret Blohm, GE's advanced technology leader for nanotechnology, says nanotech is the ultimate material science, with the potential for creating materials such as nanoaluminum with new properties, such as strength, conductivity and heat resistance, that could be used to build better diagnostic scanners or higher-efficiency energy systems. For instance, GE is pursuing ways to use high-temperature and high-strength nano-metal alloys and nano-ceramics to reduce weight in aircraft engines and allow them to run at higher temperatures, which would significantly boost fuel efficiency and decrease emissions.

Blohm says her research team recently developed diodes built from a carbon nanotube-a tiny, hollow, molecular cylinder that exhibits remarkable tensile strength and varying electrical properties-which will enable smaller and faster electronic devices with increased functionality. Unlike traditional diodes, GE's carbon nanotube device has the ability for multiple functions, which should enable it to both emit and detect light.

"Just as silicon transistors replaced old vacuum tube technology and enabled the electronic age, carbon nanotube devices could open a new era of electronics," notes Blohm. "We are excited about this breakthrough and we're eager to start developing new applications."

Another application that GE researchers are exploring is a new generation of advanced sensors that promise unsurpassed levels of sensitivity. For example, Blohm says next-generation sensors in security applications could detect potential terrorist threats from chemical and biological hazards, even if they are present in extremely small quantities. "This would enable enhanced security at airports, office buildings and other public areas," she points out.

According to Bell Labs' Bishop, in addition to sensors, "there's a lot of R&D work going on in various kinds of radio frequency components to build a radio on a chip. If you had a radio the size of a button that cost you all of 5 cents, then you could put radios everywhere. You could put a radio on your dog, on your kid, or on the book you've lent to your buddy so that you know where it is.

"There are also opportunities to create microscopic devices to repair human beings," adds Bishop. "Everything from implantable ears and eyes, to devices that go inside blood vessels to make repairs or remove clots. We are, for example, developing very sensitive sensors you can put on catheters and place inside people's hearts to measure mechanical properties of the heart."

Molecular Manufacturing

Traditionally, the typical manufacturing process involves cutting or deforming large chunks of matter, then joining together the remaining pieces into electromechanical products. In sharp contrast, molecular manufacturing-one of the long-term goals of nanotechnology-involves building complex structures by mechanochemical and nanomechanical processes.

Mechanochemical refers to chemistry accomplished by mechanical systems directly controlling reactant molecules-the formation or breaking of chemical bonds under direct mechanical control. Nanomechanical refers to a small, mechanical device, such as a robot, that can manipulate single molecules. To add an atom to a surface, researchers start with that atom bound to a molecule called a "tool tip" at the end of a mechanical manipulator.

Molecular manufacturing promises to be more efficient than traditional manufacturing, resulting in better quality products, by assembling products directly from the smallest pieces: Atoms and molecules. The basic idea is to develop a small set of chemical reactions that can be applied repeatedly to build large molecules, then control the sequence or position of the reactions by computer to build engineered molecular systems.

"Molecular manufacturing is different from biology in that biological systems are not engineered," says Mike Treder, executive director of the Center for Responsible Nanotechnology (CRN, Brooklyn, NY). The functional properties of a cell, or even a protein, are complex and hard to predict, he points out.

"However, the process of building protein molecules from small molecular fragments is quite programmable, and scientists are developing the ability to design and synthesize proteins with desired properties," notes Treder. "This will allow protein chemistry to be used in an engineering, rather than a biological, context. This would be one approach to molecular manufacturing. Other approaches using different kinds of chemistry may also work, producing better materials."

According to Treder, discussion of molecular manufacturing has often been distorted. For instance, some prominent scientists have claimed that molecular manufacturing is impossible. "However, their arguments are weak," claims Treder. "Some of the arguments elevate engineering difficulties to the status of fundamental limitations. Others are built on basic misunderstandings of the proposals.

"Although there are some practical questions remaining to be answered, there is no scientific study demonstrating a limitation or problem with molecular manufacturing theory," Treder points out. "Indeed, the chemical mechanisms of life demonstrate that machines of a sort can be constructed out of molecules and can build more machines.

"Some predicted phenomena, such as exceptionally low friction in certain cases, have been observed," adds Treder. "A single atom has been mechanically removed from a crystal and put back in the same place. Although these were not intended as demonstrations of molecular manufacturing theory, they indicate that at least some of the predictions are valid."

Some observers believe molecular manufacturing could be revolutionary. And, because chemistry is very precise and repeatable, the manufacturing operations should be reliable enough to allow complete automation. A single fabricator could build a wide variety of products by changing the control program. "Furthermore, machines built this way could have very precise features," says Treder. "This is a good thing, because building with molecules would be quite slow, and small machines can be built more quickly.

"In fact, if the calculations are right, a complete nanoscale manufacturing system could build a complete copy of itself in a few hours," claims Treder. In addition, he says it appears that the materials produced by the manufacturing system may be extremely high-performance, allowing products to be far more compact and powerful.

Nanofactory: Fiction or Fact?

Some day, nanofactories could apply the principles of molecular manufacturing and assemble products from the bottom up, molecule by molecule. Tiny machines, called fabricators, would manipulate atoms and molecules to make small parts and then join them together. A single fabricator could not build large items, so a nanofactory would include numerous fabricators and perform multiple steps to assemble products.

Many problems must be solved before a self-contained, automated, programmable nanofactory that can make useful human-scale products becomes more than just science fiction. But, Treder and his colleagues believe the concept is feasible.

To build a nanofactory, scientists need to start with a working fabricator-a nanoscale device that can combine individual molecules into useful shapes. "But, once you have that, the rest is pretty straightforward," claims Chris Phoenix, CRN's director of research. "Large-scale molecular manufacturing could be easier and faster to develop than many people think.

"An early plan for molecular manufacturing imagined lots of free-floating assemblers working together to build a single massive product, molecule by molecule. A more efficient approach is to fasten down orderly arrays of chemical fabricators, instruct each fabricator to create a tiny piece of the product, and then fasten the pieces together, passing them along within the nanofactory as on an assembly line."

Phoenix says products made by a nanofactory would be assembled from nanoblocks, which would be fabricated within the nanofactory. The product that comes out of the nanofactory would be a solid block or brick that would unfold like a pop-up book or inflate like an air mattress. "Computer-aided design programs will make it possible to create state-of-the-art products simply by specifying a pattern of predesigned nanoblocks," claims Phoenix.

A human-scale nanofactory would consist of trillions of fabricators, and could only be built by another nanofactory, Phoenix points out. But, a fabricator could build a very small nanofactory, with just a few fabricators in it. A smaller nanofactory could build a bigger one, and so on.

"Most of the mass of a nanofactory is in the form of working fabricators, and according to the best estimates we have today, a fabricator could make its own mass in just a few hours," explains Phoenix. "So a nanofactory could make another one twice as big in just a few days-maybe less than a day. Do that about 60 times, and you have a tabletop model."

Inside a nanofactory, each fabricator would make nanoblocks. According to Phoenix, a good size for a nanoblock might be a cube 200 nanometers on a side-the distance human fingernails grow in 3 minutes. "This is small enough to be made by a single fabricator in a few hours, but large enough to contain a small CPU, a microwatt of motors or generators, or a fabricator system flexible enough to duplicate itself if given the right commands," says Phoenix. "In other words, each fabricator could make a substantial piece of nanofactory functionality-and the same modular pieces would be reused in other products."

Once the nanoblocks are made, Phoenix says "they would be assembled by simple and reliable robotics. The surfaces of each block will be covered with mechanical fasteners, so that simply picking up two blocks and pushing them together will make them stick. Eight cubes will fit together to make one twice as big: A factory that makes 8 trillion nanoblocks can push them together to get a trillion larger, but still very tiny, cubes.

"The question of when we will see a flood of molecular nanotechnology products boils down to the question of how quickly the first fabricator can be designed and built," concludes Phoenix. "Every aspect of nanofactory design, other than the fabricator mechanism, is well within the capability of today's engineering practice. Building a fabricator entails chemical design, which will require significant research and development. But, there is no known reason why a basic fabricator can't be built-and then a nanofactory soon after."