Light-powered 'robot' cleans while it crawls

Clever use of shadow and light makes it walk like a caterpillar.

Scientists in the UK and Netherlands have developed the first-ever device that can "walk" along like a caterpillar using a single, constant light source for power. The concept is clever: A polymer material is installed in a frame shorter than itself to create a bulge. By shining a concentrated, violet LED on the front of the bulge, it contracts, exposing the next part of the strip to the light. That creates a continuous, relatively powerful movement that could be used to "transport small items in hard-to-reach places or to keep the surfaces of solar cells clean," the team says.

The trick relies on a light-sensitive liquid-crystal material that changes shape very quickly in the presence of light. The researchers engineered it to deform nearly instantaneously when exposed to an LED, and relax just as quickly when the light is removed. "This way, the dent moves backwards, creating a continual undulating movement [away from the light]," the team notes.

While the polymer looks transparent, it blocks 100 percent of the violet light so that the side facing away from the light remains relaxed. When it's placed upside down, the bulge moves the opposite way, causing the strip to crawl toward the light. While we've seen things like laser-powered steering before and, of course, solar-cell powered devices, it's the first walking device to use light to directly propel it.

As mentioned, the team thinks the "bots" could be used to clean solar cells or other hard-to-reach surfaces. The scientists even tested the idea, and were able to remove grains of sand with the snappy, undulating movement. Whether or not it slithers from the lab into the real world, it's a cool concept that takes awhile to wrap your head around, even when you see the video (below).