Medescape

Skepticism, Medicine and Science News

Carbon Nanotubes – What can’t they do?

Okey, so I’m not really going to write about what they can’t do. Instead, I’ll list some of the many possible applications of them, ranging from creating structural fibres to novel drug-delivery systems. 

But first, what is really a carbon nanotube? Well, it’s not really one specific thing, but rather a wide range of different nanoscale tubes made from carbon. They are based on the hexagonal arrangement of carbon atoms found in graphite, and form hollow tubes. Their discovery is often credited to the Japanese physicist Sumio Iijima who published a paper describing them in Nature in 1991, but they had in fact been observed as early as the 1950s. 

There are different types of carbon nanotubes, and one can generally divide them into single-walled and multi-walled nanotubes. The single walled nanotubes can further be divided into sub-categories based on the specific structure and arrangement of the carbon atoms. These categories are armchair, zigzag and chiral nanotubes (shown below).

 

 

There are also other types such as nanoflowers and nanobuds. But enough structure, let’s move on to applications.

Field emission: Since carbon nanotubes have such a high electrical conductivity and fine tip, they are really good field emitters. This can lead to the creation of new types of flat-panel displays. In the traditional cathode ray tube monitor, you had one electron gun creating the entire picture, but by using carbon nanotubes you could instead create individual electron guns for each pixel, thus increasing the resolution of the monitor. 

Drug delivery: As mentioned in a previous post, nanoparticles, including carbon nanotubes, can be used as “cargo hulls” for drugs. This enables the drugs to avoid excretion from the body, and can also provide a mechanism for releasing the drug directly where it is needed using a protein coating. This reduces the side-effects on other tissues. 

Other medical applications: Carbon nanotubes can also, possibly, be used to create stents for blood vessels. Scientists have also been able to grow bone cells on carbon nanotubes, which could be used to treat bone defects. They can also be used to serve as an interface between neural tissue and prosthetic electronics. Some also believe that they can, in addition to serve as a drug-delivery system in cancer, themselves damage and destroy malignant tumors. 

Structural fibers: The strength-to-weight ratio of carbon nanotubes is incredibly high, and they can therefore possibly be used to create exceptionally strong fibers. They are in addition extremely flexible, which could solve a lot of the problems we today have with heavy, fairly rigid steel cables. There is talk of using carbon nanotubes to build a space elevator, but we’re not there yet with today’s technologies. Fibers from carbon nanotubes can also be used to create new types of armour, either in the form of body armour or armour on vehicles/structures. 

Energy storage: The properties of carbon nanotubes, such as their large surface area and high electrical conductivity, makes them well suited for use in batteries, capacitors and fuel cells. A flywheel made from carbon nanotubes could potentially be used to store huge amounts of kinetic energy, possibly approaching fossil fuels in terms of energy density. 

Electrical circuits: Their high electrical conductivity also makes them suitable for other electrical applications, such as for example integrating them into plastics to make conductive plastics. They could also be used to make transistors capable of digital switching using a single electron. Their conductive properties also makes them suitable for use in radar-absorbing materials.

Other: Carbon nanotubes have been used to create so called Nano-RAM, which are much denser in terms of storage than normal RAM. Multiwalled nanotubes have also been used to create nanomotors that are able to rotate an outer shell relative to the inner core of the motor. This could further be used to power nanomachines, which could in turn be used for, among others, medical applications. 

So, the bottom line is that carbon nanotubes are amazing and can be used in almost every branch of science. I haven’t even listed half of the possible applications of them in this post, and I bet we have yet to discover a great number of other means of using them. 

Go nanotech!

 

Sources for this post:

http://www.azonano.com/details.asp?ArticleID=1143

http://www.azonano.com/details.asp?ArticleID=980#_Other_Applications

http://en.wikipedia.org/wiki/Carbon_nanotube#Discovery

http://physicsworld.com/cws/article/print/1761

http://www.wisegeek.com/what-are-flywheel-batteries.htm

http://physicsworld.com/cws/article/print/606

http://www.sciencedaily.com/releases/2006/03/060316092452.htm

http://stanmed.stanford.edu/2006fall/nano.html

http://en.wikipedia.org/wiki/NRAM

http://en.wikipedia.org/wiki/Nanomotor

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October 1, 2008 - Posted by | Other | , , , , , , ,

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