...tiny...

A few weeks ago, I wrote about the fellow who attached an outboard motor to the back of a dead pig and rode it across a lake. It's the sort of gag you really only get to do once. Nobody will pay attention the second time unless you could figure out some really radical twist to it, right? Well, two points awarded for conceptual continuity:

Only 15 years after University of California, Berkeley, engineers built the first micro-scale motor, a UC Berkeley physicist has created the first nano-scale motor - a gold rotor on a nanotube shaft that could ride on the back of a virus.

"It's the smallest synthetic motor that's ever been made," said Alex Zettl, professor of physics at UC Berkeley and faculty scientist at Lawrence Berkeley National Laboratory. "Nature is still a little bit ahead of us - there are biological motors that are equal or slightly smaller in size - but we are catching up."

[...]

Such motors could have numerous uses, Zettl said. Because the rotor can be positioned at any angle, the motor could be used in optical circuits to redirect light, a process called optical switching. The rotor could be rapidly flipped back and forth to create a microwave oscillator, or the spinning rotor could be used to mix liquids in microfluidic devices.

The motor is about 500 nanometers across, 300 times smaller than the diameter of a human hair. While the part that rotates, the rotor, is between 100 and 300 nanometers long, the carbon nanotube shaft to which it is attached is only a few atoms across, perhaps 5-10 nanometers thick.

[...]

Interestingly, the rotor does not continue spinning for long once the electricity is turned off. It is so small that it has little inertia, so any tiny electric charges remaining on the device after it's turned off tend to stop the rotor immediately.

"The nanoworld is weird - different things dominate," Zettl said. "Gravity plays no role whatsoever and inertial effects are basically nonexistent because things are just so small, so that little things like residual electric fields can play a dominant role. It's counter intuitive."

The link has an animated picture of the spinning micromotor that was shot through an electron microscope. I have a certain fascination with nanotech and read about it fairly often, but I had to laugh at this quote from Dr. Zettl: "The real breakthrough came a couple of years ago, when we discovered a method for peeling shells off multiwalled nanotubes and grabbing the core with a homemade nano-manipulator operating inside a transmission electron microscope." Every time I read that sentence, it sounds funnier. Especially reading it aloud.