A small magnetic rose sits in between two coils of copper wire in Ohio State’s Scott Laboratory. In the background, an electromagnet flips on and begins to beep. The rose’s gray petals start to slump open like the scales of a pinecone after it rains. Suddenly — the beeping stops.
Then, a high-pitched tone takes over the lab and the petals pull back upright. Another magnet turns on, and the rose whips around a few degrees clockwise.
This small rose was a demonstration of a new shape-shifting magnetic material developed by Ohio State researchers that will be used in biomedical devices, antennas, artificial muscles and robotics. The material can squeeze and grab objects and change its shape and temperature when electromagnetic fields are applied, according to the research paper published in December in the journal Advanced Materials.
Ruike Zhao, an author of the paper and assistant professor in the mechanical and aerospace engineering department, said the researchers embedded two types of magnetic particles into a soft material called a shape-memory polymer.
At room temperature, the soft material is rigid, like acrylic, she said. But when it comes within a magnetic field, the iron oxide particles heat up, softening the material so it’s like rubber, through a process called induction heating — the same technology used in some home cooktops.
When the magnetic field is turned off, the soft material will lock in place, turning rigid again as the temperature decreases. The other neodymium particles are used to control the movement of the soft material and change its shape.
Previous generations of soft materials needed a constant supply of energy, Zhao said.
“Once we deformed the [earlier] material, if we wanted to lock its deformed shape, we have to keep the external stimulation, which is not energy efficient,” she said.
Ohio State’s new material is more efficient and can lift an object 1,000 times its own weight, Zhao said.
Soft materials have existed for several decades, Liang Guo, an assistant professor in the electrical and computer engineering department, said. However, this new type of soft material with embedded magnetic particles is the first to be controlled wirelessly by magnetic fields.
Guo and Zhao previously worked together to create an insulin pump using soft materials that is one-third the size of current battery-powered pumps.
“I have the idea of the application, and she has the novel materials,” Guo said. “When the needs meets the technology, we have a good collaboration for a new project.”
Soft devices cause less stress on the surrounding skin and muscle tissues than similar mechanical devices, Guo said. They also require less energy than similar mechanical devices. The lower energy consumption allows the battery to be removed and the pumps to be powered wirelessly through skin and muscles using small antennas, called RFID — the same antennas that make wireless phone charging and contactless payments possible.
Guo’s research, which was also published in December, uses a laser beam to cut out patterns on soft film material to accomplish certain functions, such as crawling or squeezing, when an electrical current is applied.
The Ohio State team worked with researchers at the Georgia Institute of Technology to develop the polymer material, Zhao said.
“We envision this material being useful for situations where a robotic arm would need to lift a very delicate object without damaging it, such as in the food industry or for chemical or biomedical applications,” Jerry Qi, a researcher at Georgia Tech, said in a press release.
Georgia Tech researchers used the new soft material to develop prototype shape-shifting antennas that can change what frequencies they transmit or receive, Zhao said. These antennas could be used for flexible electronics or in new-generation medical implants that previously relied on multiple antennas to communicate.
“We are not just to publish papers and build some prototype device,” Guo said. “We actually want to build something useful.”