Month: May 2016

Technically, this is called Teslaphoresis. The idea is to use a Tesla coil that creates high magnitude diverging electric fields. These fields then can cause nanotubes to assemble into nanowires. Here is a page at Rice University that goes into a bit more of the details, but let me go over some of the main points.

How Does Teslaphoresis Work?

First, you need to start with a bunch of carbon nanotubes. These are collections of carbon atoms that form a cylinder. Sort of like the image below.

Next you place a bunch of disorganized nanotubes in a space in front of Tesla coil. The nanotubes then align themselves such that they form long chains. Here is a fairly detailed video.

Of course moving material with electric fields isn’t new—with Teslaphoresis this matter can be moved at much greater distances than with previous methods.

How Do You Move Neutral Matter with Electric Fields?

Let’s start with a neutral metal ball. If I place this ball in an electric field, free electrons in the metal will be pushed by this electric force so that one side of the ball becomes positive and one side negative.

However, this still would not exert a net force on the sphere. Yes, you could consider this to be an induced dipole but the electric force on the negative side is the exact opposite the force on the positive side.

But what about a diverging field? Suppose we put the same metal sphere in an electric field that looks like this.

In this case, there is still an induced dipole in the neutral metal. The big difference is in the magnitude of the electric field on the two sides of the sphere. The strength is greater on the negative side such that the net force on the sphere will be to the left. This is what you need to move neutral matter with an electric field. Actually, you can do this yourself at home. Rub a piece of plastic (a pen or comb) in your hair or on your shirt. Now bring this plastic near a thin stream of water.

It’s not the exact same thing as assembling nanotubes, but it’s kind of the same idea. If you’ve never done the “bend the water” trick, stop right now and go do it. It’s easy and awesome. You have no excuse.

What is a Tesla Coil?

In short, it’s a device used to create extremely large electric fields. You start with an oscillating current going through a coil of wires. By putting this coil next to another coil you can induce a current in the secondary coil. If the secondary coil has more loops, it can generate a higher potential difference. Really, this is the same idea as a transformer—but the Tesla coil can produce potential differences on the order of thousands of volts. Of course, a Tesla coil is only “like” a transformer. By using higher frequency currents along with a capacitor, even larger electric potentials (and thus large electric fields) can be created.

As far as I understand, the Tesla coil for this project is only used to create a high strength diverging electric field. The oscillation of this field doesn’t seem to effect the carbon nanotubes.

What Can You Do With a Nanotube Wire?

Before we address this question, there is a more important issue—how are these nanotubes connected into a wire? Here are some options:

• The individual carbon nanotubes could just be held in place with the electric field. Once the field is turned off, the nanotubes are just in a position that looks like a wire, but they aren’t really connected.
• The nanotubes could form together to make one super long nanotube wire.
• The nano wire could just be a bundle of individual nanotubes. This would be like a handful of straw of different lengths all interacting with each other.

It’s not clear to me which way they form these wires (and perhaps it’s not even clear to the researchers yet). However, I suspect that it’s the last method with interacting bits of nanotubes forming some type of bundle. If that’s the case, it is still uncertain what kind of tension this wire could withstand. Even so, here are some things you could possibly do with nanowires.

Use them as electrical wires. Not only are they thin, but carbon nanowires would have high conductivity. They could be used where ever wires are needed. But they can also be used for cases where you want thin (almost invisible wires). There are two technologies that both require a conducting surface that you can see through—solar panels and touch screens (like on your phone). I suppose that nanowires could make these devices better.

Create high tensile strength wires. It’s possible that nanowires will have the highest tensile strength for a a wire compared to any other material. What could you do with such wires? Sure, you could perhaps build a lighter faster bicycle—or you could build a space elevator. The primary idea of a space elevator is to have a large mass in geostationary orbit around the Earth with a cable running down to the Earth’s surface. An elevator (or something like that) could then ascend the cable instead of using conventional rockets.

There is another use for very thin, but high strength wires—Spider-Man’s webs. OK, that might be realistic but it’s still fun.

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