Want to build a real Transformer? No big deal, says MIT--we'll just invent a new type of motor that can power a robot as small as one cubic centimeter.

When "MIT," "robot" and "protein molecules" coincide in a single topic, odds are something cool is afoot. In this case, MIT's Center for Bits and Atoms has constructed a miniature robot about the size of a caterpillar by mimicking the structure of a protein molecule. Small robots are nothing new, but the power source behind this robot--and the way it moves--is.

The robot was designed to replicate the flexibility of protein molecules, which can be arranged into extremely complicated shapes. To reproduce that with mechanical parts on a tiny scale, MIT had to create a new type of motor:

"...the team had to invent an entirely new kind of motor: not only small and strong, but also able to hold its position firmly even with power switched off. The researchers met these needs with a new system called an electropermanent motor.

The motor is similar in principle to the giant electromagnets used in scrapyards to lift cars, in which a powerful permanent magnet (one that, like an ordinary bar magnet, requires no power) is paired with a weaker magnet (one whose magnetic field direction can be flipped by an electric current in a coil). The two magnets are designed so that their fields either add or cancel, depending on which way the switchable field points. Thus, the force of the powerful magnet can be turned off at will — such as to release a suspended car — without having to power an enormous electromagnet the whole time.

In this new miniature version, a series of permanent magnets paired with electromagnets are arranged in a circle; they drive a steel ring that’s situated around them. The key innovation, Knaian explains, is that “they do not take power in either the on or the off state, but only use power in the changing state,” using minimal energy overall."

The end goal of the robot is to be able to create virtually any 3D shape by stringing together lots of small parts. The new motor doesn't have the power to lift more than a couple segments of the chain at once, but that could change with engineering and better components.

The robot doesn't look that impressive, but once you realize that each individual segment is smaller than a quarter, it's amazing to picture dozens of tiny self-powered links forming up into an endless variety of configurations.