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Banner image: Graduate student Gregory Formosa inspects a robot that could one day change how doctors perform colonoscopies. (Credit: CU Boulder/Glenn Asakawa)

A team from CU Boulder is taking a page from The Magic School Bus and journeying inside the body. 

The researchers, led by engineer Mark Rentschler, aren’t traveling by shrinking bus like the one in the cartoon and book series. Instead, they’re using a robot that can navigate the squishy and often-unpredictable terrain of the intestine.

Rentschler and his colleagues have already built several prototypes of their gastro-intestinal explorer, although they’re still a long way from testing it in people. 

Called “Endoculus,” this machine is about the size of a C battery and moves on four motorized treads. It’s designed to crawl through a mammalian colon, seeking out and even taking biopsies of intestinal polyps and other signs of illness.

The group hopes that the robot will one day change how millions of people across the United States get colonoscopies, making these common procedures easier for patients and more efficient for doctors.

And, Rentschler said, the project might be a first step toward a new era of medicine. He envisions a future in which a wide range of medical procedures will be carried out not by doctors but by pill-sized machines—all from the comfort of your home.

“One of the things I’ve always wanted to enable is for people to swallow robots to do procedures on them,” said Rentschler, an associate professor in the Department of Mechanical Engineering. “I think the science is aligning to allow that, whether it’s in five years or 50.”

First, his team must learn how to master an environment that, in many ways, is harder for a robot to navigate than an alien planet.

“You have to forget about everything you know from a locomotion standpoint because driving around inside the body is very different than driving around in a car,” Rentschler said. “The environment is highly deformable. It’s very slick. There are sharp peaks that you have to go over.”

Test track

Top: Endoculus flips on its lights in front of a medical training device meant to mimic a human colon; middle: video from Endoculus' camera streams on a computer; bottom: Mark Rentschler (far right) stands with students (left to right) Levi Pearson, Gregory Formosa and Micah Prendergast behind an oversized synthetic colon that the team fabricated to test its robots. (Credits: CU Boulder/Glenn Asakawa, CU Boulder/Patrick Campbell)

Gregory Formosa, a graduate student in Rentschler’s lab, is getting a look at such an environment now. Formosa is taking the team’s latest version of Endoculus on a test drive through a pink plastic tube. It’s a medical training device that is meant to mimic the size and shape of a human colon.

The robot, which Formosa controls using an Xbox gaming controller, is making quick work of this unusual track. It trundles forward, bouncing over the folds, or “haustra,” of the colon—its progress visible by the glow from its LED lights. 

One of the tricks to the machine’s maneuverability lies in its treads, which have been specially-designed to gain traction on slippery digestive tissue. 

“It turns using skid steering, like a tank,” Formosa said.

That robot, which moves like a tank but looks more like a mouse, is also a fully-packed medical device complete with a camera, an air pump for inflating the colon, a water pump for cleaning and a tool port for holding biopsy snares. And, Formosa estimates, it could be built even smaller using custom parts.

Read a profile of Gregory Formosa.

The group knows that jokes about the project are inevitable. But it’s also serious business. Every year, tens of thousands of Americans die from colorectal cancer. Regular colonoscopies for people age 45 and older are widely considered to be the best way to catch such cancers early.

Pill-cams, or tiny cameras that patients can swallow to record video of their insides, are currently on the market. But, unlike Endoculus, those devices can’t stop or swivel around, said Micah Prendergast, also a graduate student in Rentschler’s group. 

“For our robots to be able to reach those regions that you reach with a pill-cam but also be able to stop and look around—that could be a big paradigm shift in the way we view these procedures,” Prendergast said. 

Read a profile of Micah Prendergast.

The researchers are currently partnering with gastroenterologist Steven Edmundowicz and his team at CU Anschutz to test Endoculus in anesthetized animals.

They’ve reported some of their recent results at the Institute of Electrical and Electronics Engineers (IEEE) and Systems in 2018 and in the journal . Tests in human patients are still several years out, Rentschler said.

Robot doctors

In the meantime, the engineer is imagining ways to take the human element out of Endoculus. His team is working to design a robot that can drive through the intestine, find worrisome polyps and biopsy them—all without a doctor at the steering wheel. 

One of the biggest challenges with such autonomous driving comes down to mapping. Human intestines, Rentschler explained, are dynamic structures that move and change shape constantly.

“How can you tell where you are and where you’re going in a place that doesn’t have GPS, that doesn’t have road signs, that doesn’t have any distinguishing marks?” he said. 

Rentschler’s team recently landed a $900,000 grant from the U.S. National Science Foundation, which has funded previous stages of this project, to continue its work in —part of his self-described mission of creating “the operating room of the future.”

He’s also quick to point out that his aim for Endoculus isn’t to get rid of physicians entirely. “But it is going to get rid of a lot of routine stuff, so that they can focus on the root causes of disease and, ultimately, treatment,” Rentschler said.

It’s a magic bus ride he’s ready to take.