Material scientists have managed to move and reconfigure a type of gel using only light.
A research team from the University of Pittsburgh has demonstrated the ability to manipulate hydrogels -- the material that most contact lenses are made out of -- and has published their work in Advanced Functional Materials.
Lead author Anna Balazs, a Pitt Distinguished Professor of Chemical and Petroleum Engineering, explains: "Imagine an apartment with a particular arrangement of rooms all in one location. Now, consider the possibility of being able to shine a particular configuration of lights on this structure and thereby completely changing not only the entire layout, but also the location of the apartment.
This is what we've demonstrated with hydrogels."
Balazs worked with associate professor Olga Kuksenok to explore the behaviour of a type of hydrogel containing spirobenzopyran molecules. Previous studies have shown that this sort of material has the extraordinary property of being "photoswitchable": in the dark it is hydrophilic (likes water) but in the light it becomes hydrophobic. It is by exploiting this property that Balazs and Kuksenok could use light to tailor the gel's shape.
The gels appeared to "run away" when exposed to light and heat, showing "direct, sustained motion". They believe this could mean that they could use light to regulate the movement of a microscopic conveyor belt or elevator made from the gel.
One of the most important properties of the hydrogels is that they could undergo dynamic reconfiguration, meaning that it can change shape multiple times by being exposed to different combinations of light stimuli. So the same sample could be used and reused for different applications.
Balazs explains: "You don't need to construct a new device for every new application. By swiping light over the system in different directions, you can further control the movements of a system, further regulating the flow of materials."
Similar properties were described in May this year, when researchers from the University of California, Berkeley, used a laser to make a graphene-based hydrogel bend.
This article was originally published by WIRED UK
