The walking polymer
Polymer goes for a walk when illuminated
Eindhoven University of Technology
The maximum speed is equivalent to that of a caterpillar, about half a centimeter per second. The researchers think it can be used to transport small items in hard-to-reach places or to keep the surface of solar cells clean. They placed grains of sand on the strip and these were removed by the undulating movement. The mechanism is so powerful that the strip can even transport an object that is much bigger and heavier than the device itself, uphill.
The motion of the new material is due to the fact that one side contracts in reaction to light, and the other one expands, causing it to bulge when illuminated. That deformation disappears instantaneously once the light is gone. Although the material looks transparent to the human eye, it fully absorbs the violet light the researchers used, thus creating a shadow behind it.
The scientific team, led by professor Dick Broer of Eindhoven University of Technology, was able to create a continual undulating movement, using this ‘self-shadowing’ effect. They attached a strip of the material in a frame shorter than the strip itself, causing it to bulge. Then they shone a concentrated led light on it, from in front. The part of the strip that is in the light, starts to bulge downward, creating a ‘dent’ in the strip. As a consequence, the next part of the strip comes in the light and starts to deform. This way the ‘dent’ moves backwards, creating a continual undulating movement. This sets the device in motion, walking away from the light. When the device is placed upside down, the wave travels in the opposite direction, causing it to walk towards the light.
The research team managed to reach this specific behavior of the material using ‘liquid crystals’ (familiar in liquid crystal displays; lcd’s). The principle relies on the incorporation of a fast responding light-sensitive variant in a liquid crystalline polymer network. They engineered a material in such a way that this response is translated to an instantaneous deformation of the strip when illuminated, and relaxation directly when the light is gone.
Original publication
Other news from the department science
These products might interest you
Spinsolve Benchtop NMR by Magritek
Spinsolve Benchtop NMR
Spinsolve is a revolutionary multinuclear NMR spectrometer that provides the best performance
Eclipse by Wyatt Technology
FFF-MALS system for separation and characterization of macromolecules and nanoparticles
The latest and most innovative FFF system designed for highest usability, robustness and data quality
HYPERION II by Bruker
FT-IR and IR laser imaging (QCL) microscope for research and development
Analyze macroscopic samples with microscopic resolution (5 µm) in seconds
Get the chemical industry in your inbox
From now on, don't miss a thing: Our newsletter for the chemical industry, analytics, lab technology and process engineering brings you up to date every Tuesday and Thursday. The latest industry news, product highlights and innovations - compact and easy to understand in your inbox. Researched by us so you don't have to.