Clouding the Picture

It can be hard, though, to see a clear picture of nanotechnology's bright future through the haze of arguments over terminology. Arguably, for example, current semiconductor manufacturing techniques operate at the nanoscale in that they meet the simple test of working with dimensions on the order of nanometers.

In the same way that a circuit designer needs an oscilloscope that has at least a 10-GHz bandwidth to accurately characterize a 1-GHz signal, a semiconductor fabrication line needs nanometer (or even subnanometer) accuracy to fabricate devices with feature sizes on the order of 20 nanometers thick, or about one thousandth the width of a human hair. That is the announced goal of Intel, for example, which hopes to produce flash memory chips on that scale around 2012.^[1]

Others, though, insist that "real" nanotechnology is the building of devices that give users molecular-level control of the content and arrangement of the components of the device, as opposed to merely working with bulk materials at nanometer scale. Consider the building of carbon nanotubes, which are cylinders made up of pentagonal rings about a nanometer in diameter. Building carbon nanotubes is a molecule-by-molecule processone that has yet to achieve the simplicity and consistency, and therefore the economy, of growing a monolithic semiconductor-grade silicon crystal.

It's certain that key nanotechnology goals depend on achieving this level of control, but progress is being made along these lines. Work published in November 2004, for example, has described the use of artificially constructed DNA molecules to orient and place carbon nanotubes between electrode pairs to create transistors.^[2]

This kind of synergythat is, the use of one kind of molecular engineering to carry out another kind of molecular construction processseems likely to be a common theme of successful nanotechnology developments.

Moreover, mass-market manufacturers such as South Korea's Samsung are already applying the properties of nanoscale materials such as carbon nanotubes to their next-generation products. Already working in prototype form, for example, are flat-panel TV screens, known as "field emission displays," that are on track for mass-market availability by the end of 2006.^[3] Functioning as an array of precise and compact electron guns bombarding a phosphor screen, a nanotube backplane allows a display designer to combine superior brightness, sharpness, and power consumption characteristics with the convenient flat-panel form.

Any consumer electronics maker that does not match Samsung's aggressive investment in this technology is rehearsing for a replay of the fate that befell competitors of Sony and Panasonic in the 1960s, when those companies essentially created the pocket-sized transistor radio as the icon of the solid-state revolution.^[4] Note well that although Sony was not the first to offer an all-transistor radio, its 1955 product was the first to come from a company that made its own transistors. Subsequent innovations, such as Sony's use of vertical-field-effect devices in FM-stereo receivers came from the same focus on core technology. Samsung's Advanced Institute of Technology (south of Seoul) represents a similar commitment of energy and resources.

It's also vital to recognize that nanomaterial applications stem from the many different characteristics of these unfamiliar substances. The electrical properties of carbon nanotubes are one thing; their thermal propertiesspecifically, the high thermal conductivity that could make them a useful addition to the heat-transferring "thermal grease" that's applied between computer microprocessors and their heat sinksare another.^[5]

Difficulties in fabrication consistency that might cripple one applicationfor example, one that depends on a consistent nanotube lengthcould be irrelevant in a task, such as heat conduction, that depends only on aggregate properties. Other such aggregate-property impacts of nanomaterials include improved air retention in tennis balls, better stain resistance in fabrics, longer shelf life and better skin-penetration characteristics for cosmetic and physical-therapy products, and reduced degradation of meat and cheese products prior to sale.^[6] These are not merely potential applications, but are actual uses of mass-produced nanomaterials that are now being incorporated into consumer products. For example, nearly half of Dockers clothing uses nanotechnology-based fabric treatments that resist stains or improve perspiration handling.

It's also important to note that nanomaterials are interesting, not merely for their size and their average properties, but for their potential of achieving unprecedented levels of consistency in many physical characteristics that were previously far below the "noise floor" of conventional manufacture. In the same way that lasers enabled new processes by offering a coherent source of perfectly monochromatic light, a nanotechnological process can deliver what we might call coherent objectsfor example, the so-called nanoshell spheres that can be precisely tailored to convert a particular wavelength of light into heat. When coated with a material that preferentially bonds to cancerous tumor cells, this property of nanoshells paves the way to a highly specific tumor-killing technique (described in Cancer Letters in June 2004) that has far fewer detrimental side effects than other cancer treatments.^[7]

Even for those who insist on infinitesimally small mechanisms, built to order from molecular-scale building blocks, the nanotechnology practitioners are ready to deliver. Prototypes of 35-nanometer mechanical valves, potentially suited to applications such as ink delivery in ink-jet printers, were constructed in 2004 from assemblies of roughly 75,000 atoms: Components derived from this work could be seen in printers by 2008, and perhaps in drug-delivery systems before 2015, according to researchers at California Institute of Technology, who demonstrated the use of a silicon beam to pinch closed a carbon nanotube.^[8]