Radio Goes Nano

Researchers in Berkeley, California, have built by far the smallest radio ever made--a nano radio. Though it's fashioned from a carbon nanotube just billionths of a meter long, the radio's creators say it's fully functional. They've even used it to play the Beach Boys' hit "Good Vibrations."

According to lead researcher Alex Zettl, the nanotube "serves simultaneously as all essential components of a radio--antenna, tunable band-pass filter, amplifier, and demodulator." But he's not just hoping to build a microscopic iPod. Since "the entire radio would easily fit inside a living cell," he thinks the nano radio should be able "to safely interact with biological systems." He even envisions "radio-controlled devices moving through the bloodstream."

Of course, if you follow the latest technology news, you know that this is just the latest example of nanotech's potential. But wait just a nanosecond. How small is a nano, really? Let's look for a little perspective.

Of Miles and Millimeters

Traditionally, human beings have measured the world in lengths ranging from a few millimeters (the size of a red ant) to a few miles (the distance you can walk in an hour). So a meter we can imagine. It's the height of a kindergartener. One-hundredth of a meter, a centimeter, is about the width of your pinkie. And one-thousandth of a meter, a millimeter, is pretty much a large grain of sand. But try to measure anything much smaller than that and you're going to need a microscope--not to mention some "tiny" terms.

Micro Means a Millionth

One-thousandth of a millimeter--one-millionth of a meter--is called a micron (or micrometer). If you could mark microns off on a ruler, 25 of them would stretch a little less than a thousandth of an inch. Human hairs are generally between 20 and 200 microns wide, while a single strand of a spider's web is 5 to 10. Many bacteria are just a micron or two long--small enough to stretch out with several friends on your split ends.

Nano Dwarfs That

A nanometer is one-thousandth of a micron--one-billionth of a meter (nanos is Greek for "dwarf"). To imagine how small that is, think of it this way. To find something a thousand times taller than you--the difference between a nanometer and a micron--you'd have to look at a mountain. To find something a billion times taller than you--the difference between a nanometer and a meter--you'd have to measure yourself against the sun.

If you were just a few nanometers tall, those bacteria stretched out on your split ends would look like a stack of skyscrapers. And the width of the human hair they're lounging on would dwarf the highest mountain you've ever seen (even if you live in Nepal). What could possibly be that small? Well, two nanometers is the diameter of a DNA helix--just wide enough to encompass the code of life.

--Steve Sampson
November 9, 2007