The world's first polymer material can move itself by light

Scientists at the Eindhoven University of Technology and the University of Kent have successfully built a new material that can move forward in a wavy fashion under the influence of light. To conduct the experiment, the scientists created a small device by clamping the ends of a sample of this polymer material with a rectangular frame. When illuminated, this device can move itself forward.

This compact device, about the size of a paper clip, is the first "machine" in the world that can convert light energy directly into kinetic energy so that it can move on its own, just one Fixed light source. The researchers published their new findings in the journal Nature on June 29, 2017.

Image: Test equipment is fitted with a new polymer object.

The maximum speed is equivalent to the speed of a caterpillar's movement, about half a centimeter per second. The researchers say the new material could be used to transport small objects to hard-to-reach places or to clean the surface of solar panels. With its wavy movement, it can remove tiny grains on the surface of the object. In addition, it can technically transport objects larger and heavier than its size.

The way this new material moves is due to the phenomenon: one side of the material will shrink due to reaction with light, and the other side will simply expand, making it swell when illuminated . The distortion will disappear immediately when the light source is disconnected. Although, with the naked eye, the material looks transparent, but actually, it absorbs all the violet light that researchers use to illuminate, and creates the shadow behind it.

The team of scientists, led by Professor Dick Broer of Eindhoven University of Technology, was able to create constant ripples using this material's "self-shading" effect. They attach this material to a frame shorter than the length of the material to help the material swell. Then, they used directional light to illuminate this device, from the front. The part of the illuminated material that swells in the downward direction will create "dent" . As an inevitable consequence, the next part of the material sample will emerge and be illuminated, will begin to deform. In such a way, the "dents" will gradually advance forward, creating continuous movement. As a result, the device can be moved in the direction away from the light source. When the device is placed face down, the ripples move in the opposite direction, so the device will move in the direction near the light source.

Video: Demonstration of testing equipment with new materials.

At the same time, the team tried to create such a phenomenon on "liquid crystal" materials (similar to liquid crystals used in LCD screens). With the basic principle still based on the rapid response of light-sensitive variants in liquid crystal polymer bonding. From there, create another form of material but there is a way to deform when directly illuminated and return to normal state as soon as the light source is disconnected.

Interestingly, when we can see firsthand the results of this study. And let's wait and see, how will they apply this material?