Soft robots, origami combine for potential way to deliver medical treatments

mhuson General, Grants, Materials and Manufacturing for Sustainability

Magnetic fields allow for wireless, faster, less invasive delivery, study finds

 

 

Researchers have found a way to send tiny, soft robots into humans, potentially opening the door for less invasive surgeries and ways to deliver treatments for conditions ranging from colon polyps to stomach cancer to aortic artery blockages.

 

The researchers from The Ohio State University and the Georgia Institute of Technology detailed their discovery, which makes use of the ancient Japanese practice of origami, in a study published Sept. 14 in the Proceedings of the National Academy of Sciences.

 

Under this system, doctors would use magnetic fields to steer the soft robot inside the body, bringing medications or treatments to places that need them, said Renee Zhao, corresponding author of the paper and assistant professor of mechanical and aerospace engineering at Ohio State. Zhao joined Ohio State in 2018 through the Materials and Manufacturing for Sustainability Discovery Theme, operated by the Institute for Materials Research (IMR). She is the director of the Soft Intelligent Materials Laboratory.

 

“The robot is like a small actuator,” Zhao said, “but because we can apply magnetic fields, we can send it into the body without a tether, so it’s wireless. That makes it significantly less invasive than our current technologies.”

 

That soft robot is made of magnetic polymer, a soft composite embedded with magnetic particles that can be controlled remotely. Robotic delivery of medical treatment is not a new concept, but most previous designs used traditional robots, made of stiff, hard materials.

 

The “soft” component of this robot is crucial, Zhao said.

 

“In biomedical engineering, we want things as small as possible, and we don’t want to build things that have motors, controllers, tethers and things like that,” she said. “And an advantage of this material is that we don’t need any of those things to send it into the body and get it where it needs to go.”

 

The soft origami robot in this case can be used to deliver multiple treatment selectively based on the independently controlled folding and deploying of the origami units. The origami allows the material to “open” when it reaches the site, unfurling the treatment along with it and applying the treatment to the place in the body that needs it.

 

Researchers have explored for decades how to leverage origami folding techniques in advanced engineering applications, such as morphing structures and devices. However, most actuation methods driving the force that is needed to enable movement and folding have been bound to external stimuli and can require excessive wiring.

 

The new, untethered system is freed from that bulkiness, allowing faster speed and distributed actuation of the multifunctional structure.

 

To demonstrate this, researchers constructed a system of magnetic-responsive materials in a cylindrical origami pattern that consists of identical triangular panels known as a Kresling pattern. This pattern allows the cylinder’s walls to buckle under axial or torsional load.

 

“The Kresling pattern offers a very rich design space, which was crucial in coupling its mechanical response with magnetically responsive materials to achieve on-demand, untethered actuation, including our multifunctional origami for digital computing,” said Glaucio Paulino, professor and Raymond Allen Jones Chair in the Georgia Tech School of Civil and Environmental Engineering.

 

By controlling the magnetic field, researchers were able to control the direction, intensity and speed of the material’s folding and deployment. In the tests, researchers achieved untethered actuation as fast as one tenth of a second with instantaneous shape locking.

 

Next, researchers attached a magnetized plate to each of the Kresling unit cells. This allowed researchers to utilize a two-dimensional magnetic field to actuate the unit cells simultaneously or independently by using different magnetic torques of the plates and distinct geometric-mechanical properties of each unit cell.

 

“The multi-unit Kresling assembly is an origami robot in which the bistable folding and unfolding create robotic motion. It can passively sense and actively respond to the external environment. By integrating electronic circuits into the origami robot, it further enables intelligent autonomous robots with integrated actuation, sensing, and decision making,” Zhao said. “For example, the external pressure or forces that act on the robot will trigger the passive folding of the robot, indicating the presence of an obstacle. The robot can then actively unfold itself and decide the next move.”

 

Researchers conducted this work in a lab, not in the human body. But the technology, they think, could allow doctors to control the robot from outside the body using only magnetic fields.

 

“In this design, we don’t even need any chip, we don’t need any electric circuit,” she said. “By just applying the external field, the material can respond itself — it does not need any wired connection.”

 

These findings may have applications beyond delivering medicine, said Glaucio Paulino, a co-author on the paper and professor and Raymond Allen Jones Chair in the Georgia Tech School of Civil and Environmental Engineering.

 

“We anticipate that the reported magnetic origami system is applicable beyond the bounds of this work, including future origami-inspired robots, morphing mechanisms, biomedical devices and outer space structures,” Paulino said.

 

This research was supported by Zhao’s two recent NSF awards from the Mechanics of Materials and Structures program (Award #1943070, #1939543) and Ohio State’s Institute of Material Research (IMR). The authors at Georgia Tech acknowledge NSF (Award #1538830) and the Raymond Allen Jones Chair.

 

Article adapted by IMR public relations coordinator Mike Huson from a Sept. 21 release by Ohio State News.