Tiny Microrobots Can Travel Through Human Body by Tumbling

Engineers at Purdue University have developed a tiny rectangular robot that is capable of operating within the human body. The new technology, which was demonstrated in live animal models, brings us closer to harnessing the power of robots for many breakthrough applications, especially in healthcare. 

The new study was published in Nature Machine Intelligence. 

The robot, which moved through the colon by doing backflips, is a drug-transport tool. Organs such as the colon are considered rough terrain, partly explaining the backflip aspect of the technology. It is the first demonstration of a tumbling microrobot in vivo.  

One of the major benefits of using a tiny robot to deliver drugs is that it can hit the exact target site. By doing this, the robot could bypass other organs which the drugs could interact with, causing side effects such as hair loss and stomach bleeding. 

The microrobot is powered and wirelessly controlled by a magnetic field on the outside. 

David Cappelleri is a Purdue associate professor of mechanical engineering. 

“When we apply a rotating external magnetic field to these robots, they rotate just like a car tire would go over rough terrain,” Cappelleri said. “The magnetic field also safely penetrates different types of mediums, which is important for using these robots in the human body.”

The colon was chosen due to its easy point of entry, as well as its difficult environment. 

Luis Solorio is an assistant professor in Purdue’s Weldon School of Biomedical Engineering.

“Moving a robot around the colon is like using the people-walker at an airport to get to a terminal faster. Not only is the floor moving, but also the people around you,” said Solorio.

“In the colon, you have all these fluids and materials that are following along the path, but the robot is moving in the opposite direction. It's just not an easy voyage.”

The tough environment makes the robot’s ability to operate within it even more impressive

Experiments

The in vivo experiments took place in the colons of live mice, which were put under anesthesia. A microrobot was first put into a saline solution before being inserted into the mice, and ultrasound equipment helped observe its movements in real time. 

The researchers also determined that the microrobots could operate successfully in pigs, due to the similarities between the guts of the animal and humans. 

Craig Goergen is Purdue’s Leslie A. Geddes Associate Professor of Biomedical Engineering. 

The microrobot was covered in a fluorescent mock drug, and it was able to successfully carry the drug throughout the solution while tumbling. 

“We were able to get a nice, controlled release of the drug payload. This means that we could potentially steer the microrobot to a location in the body, leave it there, and then allow the drug to slowly come out. And because the microrobot has a polymer coating, the drug wouldn't fall off before reaching a target location,” Solorio said.

The microrobots are made of polymer and metal, which are non-toxic and biodegradable. 

“From a diagnostic perspective, these microrobots might prevent the need for minimally invasive colonoscopies by helping to collect tissue. Or they could deliver payloads without having to do the prep work that's needed for traditional colonoscopies,” Goergen said.