talk 631

View " On the water front "
55ual

Nanotechnology has become a buzzword. It is the hottest thing since " cold fusion", which was supposed to produce energy by combining two H atoms to form a He atom in a cup of electrolyte.

Before that it was the high Tc super-conductors. Many hundreds/thousands of technical papers have been published on these two subjects of yesteryears. High Tc superconductor still is, just not as hot. Cold fusion is not around any more. So much for hot stuff.

What is nanotech? Beats me. I have not really found out yet, even though I am a team member of a research program on nano-science funded by the US government, and I honestly tried to write a portion of the of the research proposal as if I knew. So much for being funded or not being funded.

Nanotech means different things to different people; it may have a very large radius that encircles a great number of fields. Let us explore what it is here using simple physics, at about the level of what we learned from " Big Mouth Wong" at PC.

It should be obvious that nanotech deals with small things. The question is why small things are more useful than big things? That is the point, right?

Let us first define how small is small. I am under the impression that anything about 100 nanometer (nm) or smaller in size is nano-scale. One nanometer is 10^ -9 meter (10 to the minus 9 meter or 10 Å). How small is that? Well, an atom is about 0.5 nm in size (~ 5Å), so nano-scale is atomic or molecular scale. By the way, nano-things should have at least two sides with nano-dimensions, such has a nano-wire or a nano-dot, therefore a thin sheet of foil is not considered to be a nano-thing, even it is very thin.

In our daily life, we note that a sheet of paper is 100 um thick (one micron = 10^-6 meter), or about 20 bacteria stacked together (each bacterium is about 5 ums big) We can see bacteria by just using normal optical microscopes.

A bacterium is, however, about 5000 times bigger than the upper boundary of nano-things, as defined above. The definition could be different depending who you talk to. It is clear that we cannot see nano-things without a high power microscope, such as an electron microscope or a scanning probe.

Richard Feynman was often credited as the pioneer of nanotech due to his APS speech in Dec. 1959 (remember 59?) where he challenged high school students to build an engine 0.25 in^3 in size (prize money was $1000, remember gas was about or less than 20 cents a gallon). He also asked why not put the entire Encyclopedia Britannica (24 volumes in 59) on a pin head (requires atomic scale recording).

To do that he proposed to use electron microscope to "write" the words, and to "read" the words. Note that electron microscopes with atomic-resolution were not available in 1959. It was being intensely worked on at the Cavendish lab, Cambridge England. He also thought that biological systems were already writing and reading information at the molecular (or nano) scale, therefore, we ought to learn from nature. That statement implies that biologists have been working on nanotech or nano-systems for quite times now, right?

Next time we shall explore some of the unique properties of nano-things.

End of part I.