Small robots are beginning to play major roles in medicine, and there is clear evidence that nano-robots will play an even larger role, but researchers are still working out how to fabricate and automate those tiny robots. Recently, engineers from MIT have developed a new 3D printing method that is able to create tiny robot-like structures that are easily manipulated with magnetic fields. This is possible thanks to a special ink that is infused with microscopic magnetic particles. As the ink is printed, a small electromagnet on the end of the 3D printer’s nozzle is used to encode a specific magnetic field in that segment of the structure. This will cause each segment to behave differently when passed through a magnetic field.
Photo: Felice Frankel
In the image above you can see how this snowflake-like structure can transform into a crab-like device that could clutch onto a ball, walk across a surface or maybe even delivering a strong medicine to a small cyst growing on an internal organ. This is not the only shape though, and other helpful structures have been printed, such as a smooth ring that will wrinkle up, a long tube that will squeeze itself shut, and even a flat sheet that can fold itself into various shapes. The snowflake shape is by far the most interesting though as it is able to walk in a crab-like motion, and can even be manipulated enough to roll itself partially around a pill, and then walk itself across a tabletop.
Xuanhe Zhao, a professor in MIT’s Department of Mechanical Engineering and Department of Civil and Environmental Engineering heads up the project, and he and his colleagues recently published their results in the journal Nature. His co-authors include Yoonho Kim, Hyunwoo Yuk, and Ruike Zhao of MIT, and Shawn Chester of the New Jersey Institute of Technology.
This new material is part of a fast-growing segment of material science called Soft Actuated Devices and is the most promising because of its ability to instantaneously shift its shape without any significant delay. While other materials exist that can change their shape or other properties based on various stimuli, their reactions are much slower, with some taking hours or days to have altered their original shape enough to be measured. Materials such as hydrogel will swell up if the temperature or PH surrounding the gel changes. Other materials called dielectric elastomers require thousands of volts passing through them before they will begin changing shape. This is why these new 3D printed structures are so important. Since they only require a magnetic field to cause their shapes to shift, they can be easily controlled remotely without any direct, physical connection between the controller and the device.
It is worth noting, however, that other researchers have developed magnetically activated materials, but the team from MIT are the first to create structured with this much dynamic range and speed. “There is no ideal candidate for a soft robot that can perform in an enclosed space like a human body, where you’d want to carry out certain tasks untethered,” Kim says. “That’s why we think there’s great promise in this idea of magnetic actuation, because it is fast, forceful, body-benign, and can be remotely controlled.”
In addition to the ink, printer, and software that controls it, the team has developed a physical model that allows researchers to predict exactly how the structure will move when presented with a magnetic field. This model will allow researchers to work out how their structure will perform before its printed. The team has also successfully embedded an electrical circuit consisting of some conductors and a pair of LEDs in red and green. When passed through a magnetic field, the ring deforms to light the red or green LED based on the field’s orientation.
“We have developed a printing platform and a predictive model for others to use. People can design their own structures and domain patterns, validate them with the model, and print them to actuate various functions,” Zhao says. “By programming complex information of structure, domain, and magnetic field, one can even print intelligent machines such as robots.”
It’s hard not to look at these 3D printed structures and not imagine a future where a few dozen of them are deployed into a patient's body, and an MRI-like device creates multiple magnetic fields that are directing each medicine carrying robot individually to various cancers in someone’s body. It’s even easier to visualize small little robots like this helping to save lives on the battlefield as similar little robots deliver clotting agents to blood vessels and become physical plugs closing up hemorrhaging wounds.
If you would like to read the full research paper, you can find it here.
Source: MIT News
