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Using Light and Magnets to Remotely Control Movement of Soft Robots

Scientists from North Carolina State University (NC State University) and Elon University have devised a new method that enables them to distantly regulate the movement of soft robots, keep them into position for as long as required, and subsequently reconfigure them into novel shapes.

This method depends on magnetic fields and light.

We’re particularly excited about the reconfigurability. 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. All of those things are valuable, in terms of this technology's utility in biomedical or aerospace applications.

Joe Tracy, Study Corresponding Author and Professor, Department of Materials Science and Engineering, NC State

For the study, the team utilized soft robots composed of a polymer integrated with magnetic iron microparticles. The material, under normal conditions, is comparatively rigid and can retain its shape. Conversely, light from a light-emitting diode, or LED, can be used to heat up the material and this makes the polymer pliable.

Once the material becomes pliable, the scientists showed that the shape of the robot can be remotely controlled through the application of a magnetic field. After the required shape is formed, the LED light can be removed which enables the robot to regain its original rigidity, thereby successfully locking its shape in place.

When light is applied for a second time and the magnetic field is removed, the soft robots can be forced to go back to their original shapes. Alternatively, the scientists can use the light again and exploit the magnetic field to get the robots to assume new shapes or simply move them.

The scientists showed in experimental testing that the soft robots can be used for forming “grabbers” for both lifting and transporting objects. In addition, the soft robots could be employed as cantilevers, or even folded into “flowers” with petals bending in various directions.

We are not limited to binary configurations, such as a grabber being either open or closed. We can control the light to ensure that a robot will hold its shape at any point.

Jessica Liu, Study First Author and PhD Student, NC State

Furthermore, the team created a computational model that can be used to simplify the design process of the soft robots. The computational model enables the researchers to further adjust the shape of a robot, the thickness of the polymer, the direction and size of the needed magnetic field, and the abundance of iron microparticles present in the polymer before developing a prototype to achieve a particular task.

Next steps include optimizing the polymer for different applications,” Tracy stated. “For example, engineering polymers that respond at different temperatures in order to meet the needs of specific applications.”

The paper, titled, “Photothermally and Magnetically Controlled Reconfiguration of Polymer Composites for Soft Robotics,” has been published in the journal, Science Advances. Jessica Liu, a PhD student at NC State, is the first author of the paper. Jonathan Gillen, a former undergraduate at NC State; Sumeet Mishra, a former PhD student at NC State; and Benjamin Evans, an associate professor of physics at Elon University, are co-authors of the paper.

The study was performed with support from the National Science Foundation (NSF) under grants CMMI-1663416 and CMMI-1662641. It was also supported by the Research Triangle MRSEC, funded by NSF under grant DMR-1121107; and by NC State’s Analytical Instrumentation Facility and the Duke University Shared Materials Instrumentation Facility, supported by the State of North Carolina and NSF grant ECCS-1542015.


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