Although a myriad of robots is already used in a variety of industries, including medicine, they’re almost exclusively rigid devices using conventional mechanics. To best work with the pliability of the human body, it may be advantageous for medical robots to be soft and not include gears, motors, and metal cables.
Researchers at North Carolina State University and nearby Elon University have now developed such robots and have recently reported a technique that allows others to build similar devices designed for unique applications.
The robots are made using a shape-memory polymer seeded with magnetic iron particles. The material natively stays in one shape, but when slightly heated using an LED light source, it becomes soft and reconfigurable. A magnetic field is used to pull and push different parts of the robot, changing its shape. Once the desired shape is achieved, the light can be turned off and the robot will remain fixed. The device will stay still in the new shape as long as desired until it is again reheated using the light source.
“We’re particularly excited about the reconfigurability,” said Joe Tracy, one of the developers of the new robotic approach. “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.”
The team created soft grabbing devices, working cantilevers, and even folding flowers with moving petals, using their approach.
To help make each robot work and move as desired, the team also created a computer simulator that can be used to calculate how many magnetic particles to add to the polymer during manufacturing, and then how to apply the light and magnetic field.
“Next steps include optimizing the polymer for different applications,” Tracy says. “For example, engineering polymers that respond at different temperatures in order to meet the needs of specific applications.”
Study in Science Advances: Photothermally and magnetically controlled reconfiguration of polymer composites for soft robotics