Less than two weeks after a team of scientists created a nanoscale radio component, scientists at the Lawrence Berkeley National Laboratory have gone one better -- announcing the creation of the world's first complete nanoradio.
The breakthrough nanoradio consists of a single carbon-nanotube molecule that serves simultaneously as all the essential components of a radio -- antenna, tunable band-pass filter, amplifier and demodulator. Physicist Alex Zettl led the development team, and graduate student Kenneth Jensen built the radio.
"I'm totally amazed that it works so well," says Zettl. "Making individual components are good breakthroughs, but the holy grail was putting it all together. So we're ecstatic that we were able to achieve that full integration."
The radio opens the possibility of creating radio-controlled interfaces on the subcellular scale, which may have applications in the areas of medical and sensor technology.
Nanoelectronic systems are considered crucial to the continued miniaturization of electronic devices, and it's becoming a hot research and investment arena. Two weeks ago, a team at the University of California at Irvine announced the development of a nanoscale demodulator, an essential component of a radio.
The number of consumer products using nanotechnology -- from the iPhone to home pregnancy testing kits -- has soared from 212 to well over 500, according to the Project on Emerging Nanotechnologies' online inventory of manufacturer-identified nanotech goods in March 2006.
The nanoradio is less than one micron long and only 10 nanometers wide -- or one ten-thousandth the width of a human hair -- making it the smallest radio ever created.
The researchers' paper was published at the American Chemical Society's Nano Letters website.
The first transmission received by the nanoradio was an FM broadcast of Eric Clapton's "Layla." (The lab has posted video of that moment.) The Clapton classic was quickly followed by the Beach Boys' "Good Vibrations" and Handel's Largo from the opera Xerxes -- the first piece of music broadcast by radio, on Dec. 24, 1906.
The nanoradio's amplifier operates on the same principles as vacuum-tube radios from the 1940s and early '50s, says Zettl.
"We've come full circle. We're using the old vacuum-tube principle of having electrons jump off the tip of the nanotube onto another electrode, rather than the conventional solid-state transistor principle," says Zettl.
The electronic properties of this electron-emitting nanotube function as the radio's demodulator -- making a complete radio possible within a single molecule.
The audio quality "can be very good," says Zettl, but if you listen closely, some unique effects of the radio's tiny size can be heard: an old-fashioned "scratchiness" that occurs because the device is working in the quantum regime.
"The amazing thing is that since we have such a sensitive nanoscale system, individual atoms jumping on and off the nanotube cause a perturbation that you can hear," says Zettl. He notes that this effect can be eliminated through the use of a better vacuum.
Because of its small size, the nanoradio could be inserted into a living human cell, opening up the possibility of exciting medical applications for the technology, says Jillian M. Buriak, an expert in nanotechnology at the University of Alberta's chemistry department.
"These carbon nanotubes are so small that we can have a radio-controlled interface with something that is on the same length scale as the basic submachinery of the cell and the basic workings of life," says Buriak.
The nanoradio could be used to see inside cells in real time and under normal conditions, instead of current techniques, which involve "exploding the cells and going in and looking at the remnants," says Buriak.
"This device could allow you to spy on the cell and do things inside the cell at the molecular level, which is really neat," says Buriak, who is currently researching how to enable interactions between individual human neurons and computer chips.
The Lawrence Lab team is currently working on ways to integrate the radio with biological systems, says Zettl.
"We have colleagues here in Berkeley who are experts in cell biology, and aspects of biological interfaces to nano-electromechanical structures, so we're exploring the different possibilities of mating this radio with other systems to take advantage of its size and power," says Zettl.
