Carbon nanotubes are tiny cylindrical carbon tubes whose structure is like a tiny length of graphite (monomolecular carbon layer) rolled in on itself horizontally and sealed seamlessly. Much stronger in its bulk properties than graphite, nanotubes can be 100 times stronger than steel and ten times lighter. The chemical bonds between atoms in a nanotube are similar to the bonds in graphite, which are the strongest in nature. They have a variety of interesting properties -- excellent electron transporters, efficient conductors of heat, and extraordinary strength and flexibility.
One among many possible applications for nanotubes that is being researched is the possibility of a nanotube antenna. An antenna is an object that can pick up electromagnetic waves and convert them into electrical signals, or vice versa. The antenna is the most crucial part of any wireless transmission or receiving device -- without one, it can't function.
We can see progress in the development of antennae by looking at the approximate size of the smallest radio. In 1931, near the dawn of the radio era, people used vacuum tube radios. These fit on a desk or table. In 1954, people began using transistor radios, which could be held in the palm of your hand. For many decades, this was about as small as radios got. In 2002, an experimental step forward occurred with the fabrication of radio-receiving "smart dust" sensors. These were a few millimeters wide. Then, the final step, in 2007, Berkeley researchers developed the carbon nanotube antenna and radio, just a micrometer long and a few tens of nanometers wide.
Ever since carbon nanotubes were first given major attention in the early 90s, scientists have been doing calculations on how they might be used for a nanotube antenna. These calculations became reality in the early 2000s, when scientists made nanotube antennae or nanotube arrays that could serve as a nanotube antenna for light, microwaves, and radio. By altering the dimensions of the nanotube or nanotube arrays, researchers can make antennae that pick up or transmit a wide variety of electromagnetic signals.
Though carbon nanotubes have not yet been introduced as active elements in any electronic devices, nanotube antennae could find their way into cell phones and radios in the near future. Their extremely tiny size helps along with the miniaturization process, and their inherent strength makes them resistant to shock damage. In the longer term, nanotube antennae might be useful for giving signals to distributed nanobots, perhaps even medical nanobots roaming the human body.