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.