Researchers at Tufts University School of Engineering developed magnetic elastomeric composites that move in different ways when exposed to light, while researchers at MIT designed a polymer material that can change its structure in response to light.

Elastomeric composite
The light actuated materials created by the researchers at Tufts are based on the principle of the Curie temperature, the temperature above which certain materials change their magnetic properties. By heating and cooling a magnetic material, its magnetism can be turned on and off.

Biopolymers and elastomers doped with a ferromagnetic material will heat up when exposed to a laser or sunlight, temporary losing their magnetic properties until they cool down again. The movements of the material include bending, twisting and expansion.

The material could be used in a wide range of products, from tiny engines and valves, to solar arrays that bend toward sunlight.

Light-controlled polymer
The light-controlled polymer by MIT can change it structure in response to different wavelengths of light, converting from a rigid substance to a softer one that can heal itself when damaged.

The material consists of polymers attached to a light-sensitive molecule that can be used to alter the bonds formed within the material. When the material is exposed to ultra-violet light it is rigid, but when green light is shone upon it, it turns soft.

The material could be used to coat objects such as cars or satellites, giving them the ability to heal after being damaged. Another possible application for these materials is drug delivery.

Photos: Silklab/Tufts University / Felice Frankel / Demin Liu/Molgraphics