Nobody needs to reinvent the wheel, but reinventing the colonoscope is definitely worth somebody’s time. Mark Rentschler, an associate professor at the University of Colorado Boulder, is one of those people. He and his team have been working on the wormy robot, above, as a replacement for the usual flexible-camera-tube colonoscope.
“You’re basically pushing a rope through a deformable tube.”
“Don’t get me wrong, the traditional methods work very well, but they’re not pleasant for the patient,” Rentschler tells The Verge. “You’re basically pushing a rope through a deformable tube and the rope only bends when you get enough force against a wall. That’s where a lot of the discomfort comes from.”
Removing that discomfort is about more than just patient happiness. If colon cancer is caught early, “you’re almost guaranteed survival,” says Rentschler. The problem is that people are so unnerved by the idea of a colonoscopy that they just don’t get checked.
To overcome this problem, scientists are working on a number of different colonoscope designs, all of which have a degree of autonomy. Some have caterpillar treads, some have wheels, but Rentschler and his team thought the best approach would be to mimic natural movements inside the body. That’s why they settled on peristalsis as their chosen form of locomotion. This is the constriction and relaxation of muscles, and is used to move food along the bowels. So why not use it to move robots, too?
Peristalsis in Rentschler’s bot is simulated using springs made from a shape-memory alloy — a material that “remembers” its shape, and returns to it when heated. The metal is heated by a small electric current and expands outward. Then, a combination of cooling air and a 3D-printed silicon sheath covering the exterior of the bots acts as a natural “restoring force” to push them back in. “With this we can drive along and steer about,” says Rentschler. “Then we just put a camera on the end.”
The new bot was shown off earlier this month at the 2017 IEEE International Conference on Robotics and Automation or ICRA. It’s still in the prototype stage, though, and a number of improvements will need to be made if it ever makes it into hospitals (and bodies).
“We definitely want to get a little bit smaller in diameter,” says Rentschler. “And then the other big challenge is speed.” Right now, the bot can squirm along at a rate of around six inches in 15 seconds. An average colonoscopy takes about 30 minutes, and Rentschler’s aim is to get this down to the 20-minute mark. “We're close, but we do want to increase our speed,” he says.
And with a better colonoscope, lives can be saved. Not bad for a wriggly, squiggly robot.