A tubular, soft robot controlled by light can pump fluids, loosen bolts and move through pipes. The robot can also be designed to bend toward a light source, such as a plant tilting toward the sun.
In some materials, molecules can extract energy from light, causing the material to expand or contract. Jiu-an Lv at Westlake University in China used this effect to prototype a soft robot made up of a tube 15 to 40 millimeters long.
He and his colleagues wound filaments of a light-sensitive elastic material into an arrangement inspired by an elephant’s trunk, with muscle fibers joined in such a way that they can take on many different shapes, depending on which one gets strained.
Instead of the robot’s fibers responding to electrical signals from the brain, as they do in an elephant, they respond to light. When illuminated with light of different frequencies and intensities, the robot took on different shapes.
In one experiment, the researchers filled the robot with a liquid and connected it to a tube that led to an elevated container. Using light to make the robot contract, the liquid was pumped up and into the container. In another, they slid the robot through a curved tube with a bolt on the bottom. When his flexible body is connected to the bolt, the researchers eased to spin it and unscrew the bolt.
But Lv is most excited about an experiment where they figured out how to wrap the light-sensitive fibers into the shape of an artificial plant that combines the bending and twisting motions to move towards the light. If the light was very intense, the robot could also tilt away from it.
Shengqiang Cai at the University of California, San Diego, says this adaptive behavior is impressive and could be useful for developing devices that can continue to self-adjust as they absorb and collect the sun’s energy.
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