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Nanotechnology Spotlight

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Posted: Oct 17, 2008

Grappling with nanotechnology - scaling is difficult and symbols matters

(Nanowerk Spotlight) Poll after poll shows that most people today, assuming they have even heard the term, don't understand what nanotechnology is ("Landmark poll shows Americans have little to no understanding of nanotechnology"). Those who have heard about it are often misinformed by science fiction books and movies or tend to either focus on hype ("trillion dollar industry", "cures cancer within the next few years") or fear ("grey goo", "killer nanobots") surrounding available information about nanotechnologies ("Survey finds emotional reactions to nanotechnology").
The problem for non-scientists in understanding what nanotechnology represents is twofold: There is the inconceivably small scale involved. Explaining that a hair is 100,000 nanometers thick or a red blood cell is 7,000 nanometers wide really isn't very helpful – we can't picture that either. The other problem is that the way matter behaves at the nanoscale is completely foreign to our representation of reality. While our five senses are doing a reasonably good job at representing the world around us on a macro-scale, we have no existing intuitive representation of the nanoworld, ruled by laws entirely foreign to our experience (read: "Shaking hands with a virus - getting all touchy-feely with nanotechnology").
A team of scientists has described the key issues quite nicely: "There is a general recognition that few people understand the implications of the technology, the technology itself or even the definition of the word. This lack of understanding stems from a lack of knowledge about science in general but more specifically difficulty in grasping the size scale and symbolism of nanotechnology. A potential key to informing the general public is establishing the ability to comprehend the scale of nanotechnology. Transitioning from the macro to the nanoscale seems to require an ability to comprehend scales of one-billion. Scaling is a skill not common in most individuals and tests of their ability to extrapolate size based upon scaling a common object demonstrates that most individuals cannot scale to the extent needed to make the transition to nanoscale."
Let's look at this concept of "scale" for a moment. When you look at a model airplane or a map it mentions what the model's scale is in proportion to the life-size object. Another way of expressing differences in scale is by "order of magnitude" – an exponential change of plus or minus one in the value of a unit – which also can be represented as a position on a logarithmic scale. If two numbers differ by one order of magnitude, one is about ten times larger than the other. Order of magnitude is commonly expressed as a power of ten, in this case it would be 102.
Attaching the prefix "nano-" to a unit decreases the size of the unit by nine orders of magnitude, the equivalent of multiplying it by one billionth. So, a nanometer is one billionth of a meter, i.e. 10 -9 meters, or nine orders of magnitude removed from one meter.
The smallest object you could possibly see with your naked eye is a tiny speck of dust that is larger than 10 micrometers, i.e. 10-5 meters. That is still four orders of magnitude larger than a nanometer.
Let me dazzle you with even larger numbers than can give you an idea how small the nanscale is. Reports and articles about nanotechnology routinely and casually talk about detecting and manipulating single molecules. Yet the task is akin to finding a single, particular fish in the ocean. We used this example in a previous Spotlight (Sucking nanospaghetti through nanopores - the art of single-molecule spectroscopy):
In a conventional solution-based single molecule detection experiment, one can only detect approximately 10,000 molecules per minute, or one molecule every 6 milliseconds. While this may sound a lot, consider that a small drop of water (ca. 5 ml) contains approx. 1.67 x 1023 molecules. At that speed you need over 100 trillion years to detect all the water molecules in this single drop. Using a novel nanopore array developed by researchers in the UK, expect to be able to detect up to 1 million molecules simultaneously in the same 6 millisecond time window (and bringing the timeframe for analyzing all the molecules in a single water drop down to some 60 billion years - about five to six times the estimated age of the universe).
nano clover
Nano-Clover. Atomic force microscopy has emerged as an efficient tool to observe molecules deposited on a surface, specially the changes suffered after induction of external factors. The image shows fibres after treatment with ultrasounds of a bismuth cluster (2 nanometers high). (Mrs Lorena Welte Hidalgo, Universidad Autonoma de Madrid/Spain)
Almost all scientific data today is represented visually. We can marvel at amazing electron microscope images and artists' impressions of nanoscale objects – but we still don't understand the scale or the importance of what is shown to us. That's also why most people can't really get a grip on scientific discoveries unless they result in a better remote control for their TV.
In the paper we mentioned above ("Numbers, scale and symbols: the public understanding of nanotechnology"), a group of researchers at Cornell University has begun to explore the public understanding of nanotechnology with the goal of creating eductional programs and materials that help the public understand the essential concepts. In their preliminary work, they focused on the essential concept of scale – while other issues including the behavior of nanoscale materials are also important concepts, these cannot be easily addressed without a foundation in scale.
The authors argue that the absence of an ability to scale, symbolism becomes an important route to convey concepts important to nanotechnology: "The use of familiar representations of atomic-scale objects (atoms and molecules) immediately alerts the person that they are viewing something that is nanometer scale. While this might not convey an understandable absolute scale it puts the individual in the appropriate size frame. The use of familiar symbols is a more obvious route than trying to introduce a new symbol with the accompanying interpretation with the hope that the individual will assimilate this new symbol and use it."
In their tests, the researchers found that people who were asked to draw representations of nanoscale objects such as atoms, molecules or DNA commonly use simple but widely familiar iconic symbols such as a double helix or the Nagaoka model:
Nagaoka atom model
Imagine an atom. Chances are you are seeing a Nagaoka. In 1904, a Japanese physicist named Hantaro Nagaoka created the classic atom image with planet-like electrons orbiting around a nucleus.This is the picture that many people have in mind – cute, but wrong. Reality at the atomic scale is much, much weirder: atoms are mostly empty space and the solid world we are experiencing around us is an illusion.
On the other hand, of the most widely circulated nanotechnology images of a "quantum corral" is hardly recognizable as a series of atoms on a surface:
quantum corral
Quantum Corral. IBM scientists have positioned 48 iron atoms into a circular ring in order to "corral" some surface state electrons and force them into "quantum" states of the circular structure. The ripples in the ring of atoms are the density distribution of a particular set of quantum states of the corral. (Image: IBM)
One of the conclusions reached by the Cornell researchers is that in the absence of an ability to scale, symbolism becomes an important route to convey concepts important to nanotechnology: "While this might not convey an understandable absolute scale it puts the individual in the appropriate size frame. The use of familiar symbols is a more obvious route than trying to introduce a new symbol with the accompanying interpretation with the hope that the individual will assimilate this new symbol and use it."
And meanwhile, your 'reality' tells you that you are sitting in your chair right now as you are reading this, but reality at the subatomic level means that you are not really sitting in your chair – thanks to the repulsion of your and the chair's electrons you are actually floating on it at a height of a fraction of a nanometer...
By . Michael is author of two books by the Royal Society of Chemistry: Nano-Society: Pushing the Boundaries of Technology (RSC Nanoscience & Nanotechnology) and Nanotechnology: The Future is Tiny. Copyright © Nanowerk

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