Learning to Crawl

Researchers at Case Western Reserve University have developed a robotic device that moves like a slug -- it could make colonoscopies safer and easier to administer.

A team of researchers at Case Western Reserve University has created a robotic device that moves much like a slug or earthworm -- and it could ultimately become the ideal tool to help doctors perform colonoscopies.

By studying how invertebrates such as the California sea slug traverse their environment, Dr. Hillel Chiel, professor of biology at Case Western Reserve in Cleveland, and a group of biologists and engineers were able to create a flexible robot that resembles a worm or slug, imitating the movements of those creatures. Chiel says his initial interest in understanding and replicating these simple biological systems was driven by "pure curiosity." But applications for practical uses -- particularly colonoscopies -- quickly emerged.

Building on several years of work studying the movements and behavior of soft-tissue animals, Chiel's team has constructed an endoscopic device made up of three muscle-like latex actuators -- mechanisms that help the robot move in its environment -- covered in nylon mesh. The device resembles a nine-inch hollow worm with a small camera inside it. Right now, it's about a half-inch wide, but the team hopes to miniaturize it further.

By inflating and contracting the mechanism, using a self-managing movable seal system that the researchers had to create, the actuator segments move the robotic "worm" forward -- the same way its biological counterpart scrunches its body to propel itself. Doctors will use a joystick, initially connected by wire to the device, to control the direction in which it travels, says Chiel.

Chiel admits that worms aren't an obvious inspiration for engineering a new technique for performing a colon cancer screening. But its developers believe their device could be an advance in the field, allowing the diagnostic camera to move more easily through the long and twisted pathways of the large intestine, which would help doctors spot signs of cancer or bleeding more easily. 

"This device can literally 'worm' its way into complicated places or curved tubing such as the colon," says Chiel in a press release.

Working with Olympus Medical Devices, the medical systems unit of camera maker Olympus, Chiel's team has built a prototype -- it has yet to be tested on a human being -- that can be fitted like a sleeve over a medical endoscope, so that it moves the camera through a colon autonomously.

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Currently, patients need to be anaesthetized before receiving a colonoscopy, in which a long tube-like instrument with a camera is inserted into the rectum and up through the colon. As unpleasant as it sounds, the procedure is necessary to spot colorectal forms of cancer. The disease strikes more than 145,000 Americans each year, and more than 56,000 of them are expected to die in 2005, according to the American Cancer Society.

On May 19, The New England Journal of Medicine reported that the less-invasive sigmoidoscopy, in which only the lower part of the colon is examined (as opposed to the entire colon in a colonoscopy), was found to miss a majority of advanced colorectal lesions in women. By creating a colonoscope that could perform the same task more easily and with less discomfort, they hope that more people might be willing to have the screening procedure, and catch a potentially life-threatening disease early on.