Imagine a material that could turn light directly into movement, without solar panels or other energy sources. Researchers at Eindhoven University of Technology and Kent State University have developed such a material. The polymer material they used walks like a caterpillar when illuminated.

The small device, only the size of a paperclip, as first in the world converts light directly into waking, simply using one fixed light source. This is achieved by using fast-responding light-sensitive liquid crystal polymers.

The material resembles a caterpillar as it moves, pushing itself forward by arching itself. Its speed is also equivalent to that of the larva, as it ‘walks’ about half a centimetre per second.

The motion of the material happens because one side reacts to the light, contracting, while the other expands. This causes it to bulge when illuminated, but stops immediately when the light is gone. While it looks transparent to the human eye, it absorbs the ultraviolet light, thus creating a shadow behind it.

The researchers were able to create a continual undulating movement. They put the material in a frame that was shorter than the strip itself, causing it to bulge. When a concentrated light was shone on it, the material started to bulge downward. Because the material moved, a new part came into the light, which deformed. This way, the ‘dent’ moves backwards, creating a continual undulating movement, and the material moves away from the light. When turned upside down, the material walks towards the light.

The team thinks the material can be used to transport small items in hard to reach places, or to keep the surface of solar cells clean.

Photos: Bart van Overbeeke / Eindhoven University of Technology / Kent State University