For the public, the jury is still out on nanotechnology – the media simultaneously extols its promise and warns of the potential calamity facing humanity.
But what is it? How does it work? Is it dangerous?
What we now call nanotechnology has the aim of designing, controlling and probing matter at the nanoscale.
The “nano” bit refers, of course, to the size scale of nanometers, with one nanometer being one billionth of a meter. For scale, in a typical solid material, one can fit just ten atoms into a nanometer.
While no single individual invented the field, much credit goes to the US physicist Richard Feynman. In his famous address to the American Physical Society entitled There’s Plenty of Room at the Bottom, he challenged the scientific community by presenting his vision of the future of technology.
Feynman envisioned building a transistor – the core element in your computer – atom by atom, using tiny machines to build the device from the bottom up. The key concept in his vision was that of taking control of the process, instead of simply mixing things together and letting nature run the show.
Of course, various scientific disciplines such as chemistry and biology have for decades worked with matter at the atomic scale – chemical reactions take place between individual atoms, and biomolecules are studied on comparable scales. But what Feynman was describing was fundamentally different.
By emphasising the access to and control over individual systems at the scale of nanometers, Feynman realised the possibility of unlocking totally new technical capabilities.
In the scientific sense, size really matters; matter at the nanoscale behaves in a fundamentally different way than it does at the macroscale.
Where we are
Nanotechnology has developed into an extremely broad, and even loosely-defined, field encompassing research in electronics, biological systems, chemistry, materials science, and precision metrology.
We produce new materials at the nanoscale – nanoparticles and nanomaterials; engineer new active nanoscale electronic and optical elements – nanodevices; and develop new techniques to probe matter on the nanoscale – nanometrology.
Today, Feynman’s vision has been realised. We have transistors made of just a single molecule, quantum devices using individually controlled trapped atoms, and an amazing array of novel nanostructured materials in labs all over the world.
What this means for you
A wide variety of consumer products already benefit from nanotechnology.
Believe it or not, new techniques in nanomaterials growth and nanoelectronics currently appear in the microprocessor powering your computer.
Tiny transistors with insulators just one nanometer thick and lengths of just about 20 nanometers are currently in production. Leveraging these tiny size scales allows incredibly large numbers of devices to be integrated on a chip, and permits them to operate faster than their predecessors.
Then, of course, we have sunscreen. By engineering matter at the atomic scale we can produce nanoparticle forms of standard chemicals, say titanium dioxide, which absorb ultraviolet light but are invisible in the range covered by human vision.
That way, when you slather on the sunblock you don’t look grey. Other cosmetics and industrial products benefit similarly from the incorporation of nanoparticles.
We’ve certainly been hearing about the dangers of nanotechnology – from “Grey Goo” to toxic nanoparticles.
A word to the wise: Grey Goo, the concept that tiny nanomachines will overrun the Earth, is science fiction, with the emphasis on fiction.
The existence of nanotechnology in your computer’s microprocessor clearly doesn’t pose a threat of self-replicating nanobots, nor does research on new electronic or optical devices allowing scientists to study unique features of quantum mechanics.
That said, there are real health and safety issues. Taking the example of nanoparticles in sunscreen, the trade-off for making the particles invisible by reducing their size is that they become more readily absorbed into your body.
Tests have demonstated that depending on size and other characteristics, nanoparticles may be easily transmitted through cell membranes, or even pass the blood-brain barrier.
In itself, passage of nanoparticles through the body is not necessarily a problem – in fact it is a major motivation for the development of nanotechnologies in medical science.
Unfortuntely, materials that are known to be safe for human exposure can have fundamentally different chemical and toxicological characteristics when reduced to the nanoscale. Remember, size matters.
Studies have suggested that nanoparticle aggregation in various parts of the body can be hazardous to human health.
Nanotubes, for instance (imagine tiny soda straws just one nanometer wide), have been shown to aggregate in the lungs if inhaled, producing symptoms in laboratory animals similar to those created by exposure to asbestos. But other nanoparticles have been shown to be harmless, greatly complicating the issue.
The concerns are very real and require careful studies of risk.
A bit of context is always helpful. It may surprise you, but most significant sources of nanoparticle exposure are often due to natural phenomena. When you go to the beach, or there’s a dust storm you inhale large quantities of silica nanoparticles (glass).
Bush fires release large quantities of nanoparticles due to the combustion process. And perhaps most surprisingly, the milk we drink every day consists of a nanoscale colloidal suspension – little blobs of fat suspended in water.
And if you’re really concerned about man-made sources of nanoparticles you need to look at much less exotic technologies.
Perhaps the largest source of man-made nanoparticles to which we are exposed is the internal combustion engine. And we know these are toxic.
As with all technological developments, we need to be careful, but we must fight the urge to overreact. A blanket moratorium on the use or study of nanotechnology, as advocated by some environmental groups, fails to acknowledge basic science.
So moving forward, the scientific community, environmental groups, governments, industry, and the public should cooperate to produce workable and useful regulations.
Fact and science always need to form the basis of our decisions.