Nanotechnology

• 1. Introduction

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  Nanotechnology operates at a scale so small that a nanometer, measured against a meter, is the same as a marble measured against the size of the earth. That is not a metaphor. That is the literal proportion of the world this field works in. And within that near-invisible territory, matter behaves by entirely different rules. Surface area grows enormous relative to volume. Quantum effects, irrelevant at human scales, begin to govern how electrons move and how atoms bond. A particle of silver that is harmless in bulk can, at the nanoscale, kill bacteria inside a sock. A form of carbon that writes pencil marks can be woven into a tube harder than most metals. The questions that define this field are not small ones: Can we build anything we want, atom by atom? What happens to living things when they breathe particles this small? And who should decide how a technology this powerful is used?

• 2. Feynman's Invitation

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  Richard Feynman, the physicist, planted the seed of this entire field in 1959 with a talk called There's Plenty of Room at the Bottom, where he described the theoretical possibility of synthesizing materials by directly manipulating atoms. The idea sat mostly dormant for years. Then in 1974, Norio Taniguchi coined the term "nano-technology," though the word did not circulate widely. K. Eric Drexler, working from Feynman's framework, brought the idea to a wide audience with his 1986 book Engines of Creation: The Coming Era of Nanotechnology. In that book, Drexler proposed a nanoscale "assembler" capable of building a copy of itself and objects of arbitrary complexity, with atom-level control. The same year, Drexler co-founded The Foresight Institute to spread public awareness of what he believed was coming. His vision was ambitious enough to become genuinely controversial, and the arguments it triggered would eventually play out in the pages of a journal of the American Chemical Society.

• 3. Two Breakthroughs

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  In 1981, Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory invented the scanning tunneling microscope, a tool that for the first time allowed individual atoms to be seen. By 1989, that same device had been used to move individual atoms deliberately. Binnig and Rohrer received the Nobel Prize in Physics in 1986 for their invention. Binnig, Quate, and Gerber followed up that same year with the analogous atomic force microscope, extending the toolkit further. The second breakthrough arrived in 1985, when Harry Kroto, Richard Smalley, and Robert Curl discovered fullerenes, the soccer ball-shaped carbon molecules nicknamed buckyballs. Their discovery earned the 1996 Nobel Prize in Chemistry. The more consequential downstream development came in 1991, when Sumio Iijima of NEC identified carbon nanotubes, the cylindrical relatives of buckyballs that suggested practical paths to nanoscale electronics. Iijima received the inaugural Kavli Prize in Nanoscience in 2008 for that discovery. These tools and materials gave researchers something Feynman's talk could not provide: actual physical means to reach the nanoscale.

• 4. Drexler Versus Smalley

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  By the early 2000s, the field had attracted enough scientific, political, and commercial attention that its internal disagreements became very public. The central fault line ran between Drexler's vision of molecular nanotechnology, a future in which programmable assembler machines build objects atom by atom, and the skepticism of Richard Smalley, who argued that mechanosynthesis was simply impossible due to the practical difficulties of mechanically manipulating individual molecules. The two exchanged letters in Chemical & Engineering News, the publication of the American Chemical Society, in 2003. Their dispute was about more than theory. It touched on what this technology actually was, what it could become, and whether Drexler's proposals belonged in serious scientific conversation. Smalley's side held that biology already demonstrated sophisticated molecular machines, but that non-biological versions remained in their infancy and faced physical constraints that Drexler's framework underestimated. Meanwhile, Alex Zettl and colleagues at Lawrence Berkeley Laboratories and UC Berkeley built at least three molecular devices whose motion they controlled by changing voltage: a nanotube nanomotor, a molecular actuator, and a nanoelectromechanical relaxation oscillator, quietly advancing the hardware while the debate ran in print.

• 5. From Lab to Laundry

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  As of the 21st of August 2008, the Project on Emerging Nanotechnologies counted over 800 manufacturer-identified nanotech products already publicly available, with new ones reaching the market at a rate of roughly three to four per week. Most of these were what researchers call first-generation passive nanomaterials. Titanium dioxide appeared in sunscreens, cosmetics, and food products. Silver nanoparticles turned up in food packaging, clothing, disinfectants, and household appliances. Zinc oxide moved into paints and outdoor furniture varnishes. Carbon nanotubes were developed for stain-resistant textiles. Tennis balls lasted longer. Golf balls flew straighter. Bowling balls became more durable. Bandages infused with silver nanoparticles were designed to accelerate wound healing. In the electric car industry, single-wall carbon nanotubes addressed core challenges in lithium-ion batteries, including energy density, charge rate, service life, and cost. None of these products involved the atom-by-atom assembly Drexler had envisioned. They were extensions of existing materials science, using nanoscale dimensions to push the performance of familiar things. And they were arriving faster than the regulatory frameworks designed to assess them.

• 6. Health Shadows

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  A two-year study at UCLA's School of Public Health found that lab mice consuming nano-titanium dioxide showed DNA and chromosome damage to a degree researchers linked to cancer, heart disease, neurological disease, and aging. A study published in Nature Nanotechnology concluded that certain forms of carbon nanotubes, if inhaled in sufficient quantities, could prove as harmful as asbestos. Anthony Seaton of the Institute of Occupational Medicine in Edinburgh said plainly of those nanotubes: "We know that some of them probably have the potential to cause mesothelioma. So those sorts of materials need to be handled very carefully." Research showed that when rats breathed airborne nanoparticles, the particles settled in the brain and lungs, triggering measurable increases in biomarkers for inflammation and stress. Silver nanoparticles released during the washing of treated socks were shown to flush into wastewater streams, where they risked destroying bacteria essential to natural ecosystems, farms, and waste treatment. A Royal Society report specifically flagged the risk of nanoparticles being released during the disposal, destruction, and recycling of products, and called on manufacturers to publish procedures for managing those materials. Andrew Maynard, chief science advisor to the Woodrow Wilson Center's Project on Emerging Nanotechnologies, reported that funding for human health and safety research remained insufficient, leaving the understanding of risks incomplete as the products multiplied.

• 7. Medicine and What Comes Next

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  Nanoencapsulation, which encloses active substances within nanoscale carriers, has already changed how some drugs reach the body. These carriers improve the bioavailability of drugs that dissolve poorly in water, allow controlled and sustained release, and support targeted delivery that reduces side effects. Progress has also been made in tissue engineering, where researchers attempt to mimic the nanoscale features of a cell's natural environment to guide how cells develop. When building scaffolds to support bone growth, for instance, researchers have looked to osteoclast resorption pits as a structural model. Researchers also used DNA origami-based nanobots, capable of executing logic functions, to deliver targeted drugs in cockroaches. Mihail Roco proposed a four-stage model for the progression of nanotechnology, moving from passive nanostructures to active nanodevices, then to complex nanomachines, and finally to productive nanosystems capable of generating atomically precise parts for other nanosystems. If that last stage arrived, he suggested, it could form the basis of another industrial revolution. The Technion built a nano bible, a 0.5 square millimeter silicon chip containing the entire text, partly as a demonstration of current capabilities and partly to increase youth interest in the field. Ho and Lee at Cornell University, working in 1999, used a scanning tunneling microscope to move a single carbon monoxide molecule onto an individual iron atom resting on a flat silver crystal, then used a voltage to chemically bond the two together. That kind of precision, once a thought experiment in a 1959 lecture, is now laboratory routine.