Such is not the case with a new bot, however, which utilizes a phenomenon of physics to automatically move its inflatable legs.

Designed by Alberto Comoretto, Mannus Schomaker and Bas Overvelde at the Netherlands' AMOLF institute, the tiny robot has been built in both two- and four-legged variants. In both cases, each leg consists of a loop of elastomer tubing with a kink in it.

As air is smoothly and continuously pumped into that leg, the kink moves down the length of the tube, causing it to oscillate. It's the same principle which is at work in the gyrating inflatable "tube dancers" used to promote businesses.

When the robot's legs are initially activated, they move chaotically.

Within milliseconds, however, as they interact with one another and with the terrain, they automatically all start moving in unison. The bot is then capable of scooting at speeds of up to 30 body lengths per second (on flat surfaces), which is far faster than any other air-powered robot.

If the robot breaks its stride upon stumbling on an obstacle or uneven terrain, its legs get back into sync as soon as it picks up speed again. And even more impressively, due to the physical properties of liquid, the buoyant bot automatically adopts a back-and-forth alternating-leg swimming gait when it enters the water.

"Simple objects, like tubes, can give rise to complex and functional behavior, provided we understand how to harness the underlying physics," says Assoc. Prof. Overvelde. "There is no brain, no computer ... But when properly designed, it can outperform many robotic systems and behave like an artificial creature."

It is hoped that the technology could one day be utilized in applications such as micro-robots that deliver medication within the body, energy-efficient assistive exoskeletons, or machinery designed for use in harsh environments where electronics may fail, such as outer space.