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Tufts University develop new materials that move in response to light

Penelitian - Tufts University School of Engineering at Medford developed magnetic elastomer composites that move in different ways when exposed to light. The new findings open up the potential possibilities of these materials in a wide range of products to perform simple, complex movements as small engines and valves to solar arrays when exposed to sunlight.

The researchers report the findings in the Proceedings of the National Academy of Sciences regarding artificial material from many examples in biology in which light induces movement or changes in flowers and leaves swerve toward sunlight that the temperature above certain materials will change the magnetic properties.

Penelitian Tufts University develop new materials that move in response to light

Biopolymers and elastomers doped with ferromagnetic CrO2 will heat up when exposed to laser light or sunlight, while losing magnetic properties until it cools back. The basic motion of the material is formed into films, sponges, and hydrogels to be induced by a permanent electromagnet and exhibits flexural, twisting, and expansion properties.

"We can combine these simple movements into more complex movements, such as crawling, walking, or swimming. These movements can be triggered and controlled wirelessly using light," said Fiorenzo Omenetto.

The team demonstrated several complicated movements by building a soft gripper that captures and releases objects in response to light illumination. Unlike other light-driven materials based on liquid crystals, these materials can be formed to move in or away from the direction of light.

"One of the advantages of these materials is that we can selectively activate parts of the structure and control using local or focused light. These features add the ability to create large and small objects with complex and coordinated movements," Meng Li said.

The researchers built a simple "Curie engine". The film is driven by light and shaped like a ring and mounted on a needle post. It is placed near a permanent magnet when the laser is focused to a fixed spot on the ring that locally divagnes the ring portion to create an unbalanced mesh style that causes the ring to spin.



The materials used to create light-driven materials include polydimethylsoloxane (PDMS) which is a transparent elastomer and widely used as flexible film and fibroin silk which is a versatile biocompatible material with excellent optical properties.

"Additional material patterns, light patterns and magnetic field control can theoretically achieve more elaborate and more subtle movements, such as folding, microfluidic switch valves, nano-sized micro machines and more," Omenetto said.

Journal : Meng Li et al. Flexible magnetic composites for light-controlled actuation and interfaces, PNAS, July 23, 2018, DOI:10.1073/pnas.1805832115

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