New research shows ability to control soft robots with light, magnets

Ben Evans, associate professor of physics, is part of a research team looking into developing the new technology that could have application in the biomedical and aerospace fields.

​Newly published research by a team including Associate Professor of Physics Ben Evans and researchers from N.C. State University shows the possibility of controlling soft robots with light and magnetic fields, with the new technique to likely be applied to the biomedical and aerospace fields.

In a paper published Aug. 2 in the journal Science Advances titled “Photothermally and Magnetically Controlled Reconfiguration of Polymer Composites for Soft Robotics,” the research team demonstrated for the first time the ability to remotely control soft robots, lock them into position and later reconfigure them into new shapes or have the robot return to its original shape.

“An important aspect of all this work is being able to manipulate materials in a non-contact way,” said Evans, who was integral to the modeling and simulation work on the project, which is supported by grants from the National Science Foundation.

The team previously demonstrated the ability to remotely control soft robots — devices made from highly flexible materials that function similar to living organisms — using magnetic fields. The technique allows for devices to be moved without having to rely upon electricity or pneumatic force.

The big step forward with the research now is the ability to use light to control whether the robot is flexible or rigid, and to then have the robot return to its original shape. The researchers used soft robots made of a polymer embedded with magnetic iron microparticles that is stiff and holds its shape under normal circumstances.

Shining an LED light on the robot makes the robot pliable, and when a magnetic field is then applied, the robot can be manipulated into different shapes. Once the light is removed, the robot again becomes rigid and holds its shape, even when the magnetic field is removed. Shining the light again on the robot again causes it to return to its original shape, or if a magnetic field is also applied again, the robot can be moved into a different shape.

“The shape memory effect is a new piece,” Evans said.

During testing, the team demonstrated that soft robots can be used to form “grabbers” for lifting and transporting objects. They can also be used as cantilevers or folded into “flowers” with petals that can bend in different directions. During experiments, the researchers used a “flower” robot to grab and hold a blueberry and a cherry tomato before releasing them.

Evans is excited about the potential to deploy this new technology in the biomedical field, particularly in medical diagnostic devices. Advances are being made in producing a “lab on a chip” that integrates several laboratory functions on a small circuit that is no larger than a few square centimeters and likely smaller. Evans said the team’s research could allow for the magnetic manipulation of small channels of liquid on the chip, essentially opening and closing valves and doorways.

This research has established a foundational model that will now allow for the robot’s shape and composition to be fine-tuned, with ongoing research focusing on how to use magnetic fields to manipulate the robot’s shape in new ways.

​“We’re at the point where we’re exploring what’s possible,” Evans said.

The work was conducted in collaboration with Jessica Liu, Jonathan Gillen, Sumeet Mishra, and Professor Joseph Tracy of N.C. State University with support from the National Science Foundation (NSF) under grants CMMI-1663416 and CMMI-1662641. The work was also supported by the Research Triangle MRSEC, which is funded by NSF under grant DMR-1121107; and by NC State’s Analytical Instrumentation Facility and the Duke University Shared Materials Instrumentation Facility, which are supported by the State of North Carolina and NSF grant ECCS-1542015.