Friction and Sticking


Now we ask, "What does happen differently with small things?" First of all, we can make them in very great numbers. The amount of material you need for the machines is very tiny, so that you can make billions of them for any normal weight of any material. No cost for materialsall the cost is in manufacturing and arranging the materials. But special problems occur when things get smallor what look like problems, and might turn out to be advantages if you knew how to design for them.

One problem is that things stick together by molecular attraction. Now friction becomes a difficulty. If you were to have two tungsten parts, perfectly clean, next to each other, they would bind and jam. The atoms simply pull together as if the two parts were one piece. The friction is enormous, and you will never be able to move the parts. Therefore you've got to have oxide layers or other layers in between the materials as a type of lubricantyou have to be very careful about that or everything will stick.

On the other hand, if you get still smaller, nothing is going to stick unless it's built out of one piece. Because of the Brownian motion, the parts are always shaking; if you put them together and a part were to get stuck, it would shake until it found a way to move around. So now you have an advantage.

At the end of it all, I keep getting frustrated in thinking about these small machines. I want somebody to think of a good use, so that the future will really have these machines in it. Of course, if the machines turn out to be any good, we'll also have to make the machines, and that will be very interesting to try to do.




Nanotechnology. Science, Innovation, and Opportunity
Nanotechnology: Science, Innovation, and Opportunity
ISBN: 0131927566
EAN: 2147483647
Year: 2003
Pages: 204

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