The next time you touch carbon nanotube, beware!! Recent scientific studies showed that carbon nanotube can be cancerous!! Carbon nanotube has generated a lot of hype in recent years. For example last year, UC Berkeley scientists have demonstrated the world’s smallest raido using single carbon nanotubes.

A group of scientists led by Professor Kenneth Donaldson at the University of Edinburgh in the UK has carried out an experiment on the effect of prolonged carbon nanotube exposure on mice. These mice showed inflammatory response after long exposure to carbon nanotubes, indicating a sign of mesothelioma which is a form of cancer that is almost always caused by previous exposure to asbestos (Ref). The scientists found out that carbon nanotubes could release asbestos into the air if it was handled inappropriately or incorrectly (Ref).

The result was also confirmed by another group led by Jun Kanno and Akihiko Hirose of Japan’s National Institute of Health Sciences. They observed the formation of cancerous lesions consistent with mesothelioma when they injected Multi-walled carbon nanotubes into the abdominal cavity of mice that were genetically predisposed to develop cancer quickly (Ref).

How ironic is this world. We are blessed with the 21st century most wonderful material - carbon nanotube, yet we have to be extremely carefully when dealing with it.

Last week over the lunch, I heard from a colleague of mine mentioned about physicists at the University of California at Berkeley have built the world’s smallest radio out of single carbon nanotube. I was really thrilled by this breakthrough in nanotechnology. I did some googling on this breaking news and these are what I have dug out (Ref):

• The researchers called the device as the nanoradio. The tiny radio can play songs and sounds broadcast by both AM and FM radio stations, in the commercial range of 40-400 MHz. The first song played by the CNT radio was Eric Clapton’s “Layla,”.
• The nanoradio is not a miniature version of an electronic radio. It is actually a NEMS (NanoElectroMechanical System) device operating on electro-mechanical movement. When a radio wave of a specific frequency impinges on the nanotube it begins to vibrate vigorously. An electric field applied to the nanotube forces electrons to be emitted from its tip. This electrical current may be used to detect the mechanical vibrations of the nanotube, and thus listen to the radio waves.
• The nanoradio needs only a battery and a pair of earphones to hook listeners up with their favourite radio stations.
• The image of the nanoradio, taken by a transmission electron microscope, is shown above. It is a single carbon nanotube protruding from an electrode. This nanotube is less than a micron long and only ten nanometers wide, or 10000 times thinner than the width of a single human hair.
• The details of nanoradio was published in Nano Letters. You can download this classic paper in pdf format here.