Page 54 - Plastics News July 2017

TECHNOLOGY

Scientist develop polymer that undulate and propel itself forward

under the influence of light

cientists at Eindhoven University of Technology and downward, creating a 'dent' in the strip. As a consequence,
SKent State University have developed a new material the next part of the strip comes in the light and starts to
that can undulate and therefore propel itself forward deform. This way the 'dent' moves backwards, creating a
under the influence of light. To this end, they clamp a continual undulating movement. This sets the device in
strip of this polymer material in a rectangular frame. When 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.

illuminated it goes for a walk all on its own. This small
device, the size of a paperclip, is the world's first machine Antibiotic-releasing polymer
to convert light directly into walking, simply using one
fixed light source. The researchers publish their findings to simplify treatment of
on 29 June in the scientific journal Nature. prosthetic joint infection

The maximum speed is equivalent to that of a caterpillar, team of Massachusetts General Hospital (MGH)
about half a centimeter per second. The researchers
think it can be used to transport small items in hard-to- A investigators has developed an antibiotic-releasing
reach places or to keep the surface of solar cells clean. polymer that may greatly simplify the treatment
They placed grains of sand on the strip and these were of prosthetic joint infection. In their recent report
removed by the undulating movement. The mechanism is published in Nature Biomedical Engineering, the
so powerful that the strip can even transport an object researchers describe how implants made from
that is much bigger and heavier than the device itself, this material successfully eliminated two types of
uphill. The motion of the new material is due to the fact prosthetic infection in animal models.
that one side contracts in reaction to light, and the other "Currently, most infections involving total joint
one expands, causing it to bulge when illuminated. That replacement prostheses require a two-stage surgery,
deformation disappears instantaneously once the light in which the patient's daily activities are largely
is gone. Although the material looks transparent to the compromised for four to six months," says Orhun
human eye, it fully absorbs the violet light the researchers Muratoglu, PhD, director of the Harris Orthopædics
used, thus creating a shadow behind it.
Laboratory in the MGH Department of Orthopædic
The scientific team, led by professor Dick Broer of Surgery, a co-author of the report. "Our finding that
Eindhoven University of Technology, was able to create a polyethylene, the most commonly used weight-
continual undulating movement, using this 'self-shadowing' bearing surface in total joint surgery, can be made to
effect. They attached a strip of the material in a frame safely and effectively release antibiotics implies that
shorter than the strip itself, causing it to bulge. Then fully weight-bearing implants made with this material
they shone a concentrated led light on it, from in front. could be used to treat infection in a single procedure.
The part of the strip that is in the light, starts to bulge

Plastics News | July 2017 54