Soft robots are being eyed for numerous applications for which their rigid counterparts aren’t well-suited—including working alongside humans, squeezing into tight places, and delivering medications and therapies inside the body.

One key area of research is how to control these robots remotely and effectively so they can perform their tasks without being limited by wires.  To solve this problem, researchers at North Carolina (NC) State University and Elon University have developed a technique to remotely control the movement of soft robots using light and magnetic fields, and designed robots that use this method.

Researchers at North Carolina(NC)  State University demonstrate the rotation of a “flower” robot with six petals using light and magnets. Turning on the LED in sync with the rotation of every second petal beneath the magnet causes lifting of alternating petals, which remain lifted. (Image source: Jessica A.-C. Liu, NC State)

The technique enables researchers not only to control movement of robots, but also to lock them into position for as long as needed and later reconfigure them into new shapes, said Joe Tracy, a professor of materials science and engineering at NC State who led the research.

That latter capability is particularly useful for applications in biomedical and aerospace, where robots can perform various tasks and may need to be repurposed on the fly, he said.

“By engineering the properties of the material, we can control the soft robot’s movement remotely; we can get it to hold a given shape; we can then return the robot to its original shape or further modify its movement; and we can do this repeatedly,” Tracy said in a press statement. “All of those things are valuable, in terms of this technology’s utility in biomedical or aerospace applications.”

Reconfiguring Robots–and Materials

While researchers were focused on creating a method to reconfigure robots remotely, they also had to manipulate the material to make it more flexible to suit their needs, they said.

Researchers developed the robots using a polymer embedded with magnetic iron microparticles, which typically is stiff and holds it shape. To make the material more pliable, researchers heated it using light from an LED, then demonstrated how they could control the shape of a robot made from the material by using a magnetic field.

Once researchers achieved the shape they wanted the robot to have, they allowed it to resume the original material stiffness, which resulted in locking the shape into place, they said. To get the robots to return to their original shapes, researchers applied the light again and removed the magnetic field.

They also demonstrated another option to change the robot’s shape and movements by be applying the light again and using the magnetic field to move the robots or take new shapes, researchers said. Researchers published a paper describing their method and experiments in the journal Science Advances.

Experimenting with Shapes

Researchers conducted experiments in which they demonstrated different configurations for soft robots. One was as “grabbers” that can lift and transport objects, which could be useful in factory assembly lines. Other robots researchers developed included a cantilever that folded into flower-like shapes with “petals” that bend in different directions, they reported.

“We are not limited to binary configurations, such as a grabber being either open or closed,” Jessica Liu, first author a Ph.D. student at NC State who worked on the research, said in a press statement. “We can control the light to ensure that a robot will hold its shape at any point.”

To facilitate future designs, researchers also created a computational model for streamlining the design process, they said. The model allows them to optimize a robot’s shape, polymer thickness, the amount of iron microparticles in the polymer, and the size and direction of the required magnetic field before fabricating a soft robot aimed at carrying out a specific task.

The team plans to continue its work to optimize the polymer for different applications, Tracy said. “For example, engineering polymers that respond at different temperatures in order to meet the needs of specific applications,” he said in the press statement.

Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.

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