Nanotechnology and Risk, Part 1

Over the next several days, CRN will publish five weblog installments analyzing nanotechnology and risk, covering both existing and near-future nanoscale technologies as well as medium-future molecular manufacturing. We will compare and contrast the two fields that take the name "nanotechnology", and finish with our recommendations for managing the risks presented by nanotechnology.

Part 1 (today) is an overview of existing nanoscale technologies. Part 2 will assess the risks of nanoscale technology. Part 3 is an overview of molecular manufacturing, and Part 4 addresses the risks of molecular manufacturing. Part 5 will be a conclusion with recommendations.

Part 1: Nanoscale Technologies Overview

Nanoscale technologies include many diverse fields. This installment will give a flavor of what the technology is about and how it works. Nanoscale features are used in a variety of applications including computers, disinfectants, self-cleaning surfaces, stronger plastics, medicines, solar cells, biological research, and materials science. These applications depend on a surprising variety of physical principles and means of manufacture.

One way to make nanoscale particles is simply to vary existing manufacturing processes. Grinding bulk materials finer, or condensing gases more quickly, can create smaller particles. Nanoscale structures can also be made chemically. Chemists have learned to make large, precise, branching molecules called dendrimers. Some chemicals can self-assemble into larger patterns, sticking together as regions of the chemical attract each other in particular ways. Non-molecular particles can also stack up, forming quasicrystalline arrays. Then there are a variety of ways, collectively called lithography, to form nanoscale features on an existing surface.

New physical and chemical structures can display new features. For example, smaller particles of a catalyst can be more active, not just because of increased surface area, but because of increased strain between the atoms. Other particles may trap electrons in ways that make them glow in specific colors or make them useful for new computer circuit designs.

Sometimes, simply arranging nanoscale objects more precisely can be helpful. New techniques for making single layers of molecules can be used for better semiconductors, sensors, surface characteristics, structural properties, and displays.

Tools to deal with the nanoscale also are called nanotechnology, because they sense or manipulate on the nanometer scale. These tools may not actually incorporate many nanoscale components. For example, the only nanoscale part of a scanning tunneling microscope (other than in the computer chips) is the scanning probe tip. And that is sometimes made by the low-tech technique of cutting a wire with an ordinary pair of scissors.

Carbon nanotubes are a hot topic in nanotechnology. Conceptually, a carbon nanotube is formed by rolling a thin strip of graphite rolled into a tube and chemically stitching the edges together. Carbon nanotubes are extremely strong. Depending on how the graphite is twisted, they may be excellent conductors, semiconductors, or insulators. They are unusual in that they are single molecules, with precise chemical formulas, but may be thousands of nanometers long. Carbon nanotubes are being investigated for use in electronics as well as for reinforcing plastic and making it conductive.

Tiny particles of gold absorb certain colors of infrared light, heating up as they do. If attached to a chemical that seeks out cancer cells, the particles will cluster around even tiny tumors. Shining infrared light on the patient will then overheat and kill the tumors without damaging the rest of the body.

Nanoscale technology does not build complete products, only components. The wide diversity of applications means that substantial research is necessary to develop the new applications. But small size, new structures, and greater precision can improve performance in a variety of ways. Less material may be needed; stronger components can be made; new optical and electronic elements promise to shrink computers by a hundredfold; hybrids of molecules and nanoparticles can have significant medical uses including destroying tumors without harming surrounding tissue. This combination of improved performance and new applications makes nanoscale technologies well worth investigating, and a wide variety of large and small companies, as well as academic research institutions, already are doing so.

Tune in tomorrow for Part 2: Risks of Nanoscale Technology.

Comments

[John B]

Chris - the line, "Nanoscale technology does not build complete products, only components" is disingenious, at best, given the history of speculation, conceptualization, etc done elsewhere on this same web page. Perhaps "Current nanoscale technology..." might be a viable option?

Otherwise, a very fair, evenhanded response. Well written.

-John

[Chris Phoenix, CRN]

Nanoscale technology is inherently limited; it can't build anything with lots of complexity, because it doesn't include a general-purpose manufacturing system. I expect this to remain true for the foreseeable future. So I don't expect nanoscale technology to move beyond the component stage. Even MEMS need to be packaged.

Chris

[John B]

OK, so MEMS need to be packaged. Fine and good - what's wrong with packaging them in diamondoid?

Additionally, were you not talking about building an electric car out of nanoassembled carbon materials on this very site? Using high-pressure water for bulk & kinetic dissipation, but that's added after the fact? What would be the limiting factor in building such a device, as compared to building the parts individually and using human/robot labor to put the parts together? Simply a larger nanofactory 'surface'? A more complex program?

Considering that nanotech *can* self-replicate with 'n' pieces each approximating-but-less-than the complexity of a Pentium (per Toth-Fejel's study), how complex can we expect nanotech to be able to make things? It's repetitive, but so're battery cells, wires, etc.

Or am I utterly missing something here, something I'm apparently good at. *wry grin*

-John

[Chris Phoenix, CRN]

John, I use the term "nanoscale technology" to mean "the stuff the NNI is working on--using big equipment to build small low-information nanoproducts." So nanoscale technology is a separate category from molecular manufacturing/MNT.

Chris

[John B]

Fair enough.

Suggestion/request - please put together a dictionary of terms you're using somewhere for people to reference. Either here or wisenano, or wherever else. Otherwise it's kind of a dirty trick, switching terms with no clear definition.

-John

[Mike Treder, CRN]

There is an online glossary at Nanotechnology Now that we assisted in compiling. It doesn't have "nanoscale technology" in it, and some of the definitions keep evolving so it may not always be up to date -- but it's a start.

[John B]

Thanks, Mike. Any plans to update or suppliment it?

-John

[Rocky Rawstern]

John: we're always adding new terms, and updating those that need it.

Please let me know if you have any suggestions.

To view a larger "nanotech" glossary, see:

http://www.nanotech-now.com/nanotechnology-glossary-N.htm

[Ram]

Can anyone please advice on the use of nano technology in disinfectant products? Thank you.