Steve Mellon, Post-Gazette
	Metin Sitti, director of Carnegie Mellon University's Nanorobotics Lab, with his six-legged intestinal robot. MORE COVERAGE Of beetle bristles and beetle juice Online Graphic: Intestinal locomotion

The words "intestinal bug" could gain a whole new meaning if a Carnegie Mellon University engineer is successful in his efforts to develop a medical robot for examining the intestinal tract.

Metin Sitti, director of the NanoRobotics Lab, is developing a set of legs that could be incorporated into the swallowable camera-in-a-pill that has become available in the past four years for diagnosing gastrointestinal disorders in the small intestine.

The capsule camera snaps thousands of pictures as it makes its way slowly through the narrow tract, carried by the wave-like peristaltic motion that moves all contents through the intestines.

But Sitti is hoping that adding legs to the capsule will give physicians a measure of control. The work is supported by the Intelligent Microsystems Center in Seoul, Korea, and sponsored by the Korean Ministry of Commerce, Industry and Energy.

In the simplest scheme, the capsule could deploy three legs, creating a tripod that could stop the capsule's movement through the intestine, giving doctors a chance to take a closer look at something.

Polymer pads on the leg tips, mimicking the adhesive foot pads of the palmetto beetle, would stick to the intestinal walls. The adhesive foot pads require very little pressure, yet enable the beetle to withstand forces of more than 200 times its body weight.

A more elaborate, telescoping capsule, featuring a set of three legs on either end, would enable it to crawl as if it were inchworm. The capsule could thus go rapidly to a point of interest or, if sufficient power was available, move upstream to give doctors a second look at a suspicious lesion.

If that proves possible, "I think it will be a big step forward," said Dr. Ragu Appasamy, chief of gastroenterology at UPMC South Side. Being able to take a prolonged look at a suspicious lesion, or a second look, would be helpful in many cases, he said.

Appasamy, who has discussed future collaborations with Sitti, said it also would be helpful if the robot could be equipped to remove biopsies of lesions for lab analysis to see if they are malignant.

Sitti's work is still in its early stages, however. Thus far, he has devised a simple, three-footed apparatus less than two-thirds of an inch in diameter to test its stopping power in flexible plastic tubes and, in preliminary testing in South Korea, in pig intestines. A six-footed apparatus for testing the inchworm-like locomotion has been assembled and will soon be ready for testing.

The legged devices thus far do not incorporate a camera and are not designed to be swallowed.

Technologists have long speculated about the potential for medical/surgical robots that could maneuver inside the body. Another CMU roboticist, Cameron Riviere, is developing his own robotic inchworm that would use suction pads to adhere to the exterior of a beating heart. The two-footed device, called HeartLander, might be used to inject cells or drugs, implant electrodes or perform coronary artery bypass procedures.

Proponents of nanotechnology -- devices measured in billionths of a meter, or nanometers -- have proposed the fantastic vision of whole swarms of tiny robots being injected into a patient, where the robots would work together to deliver medication or perform surgery.

Those nanorobots are still far in the future, but Sitti said the technology for his microcapsule robot could be achieved within two or three years.

Swallowable cameras, which were pioneered by Israel's Given Imaging but now are being developed by several companies, already have changed the treatment of gastrointestinal bleeding and inflammatory bowel disease.

"The small bowel was really the black box for gastroenterologists," said Dr. Paul Lebovitz, chairman of gastroenterology at Allegheny General Hospital. Unlike the colon, stomach and upper GI tract, the small intestine was beyond the reach of viewing instruments, called endoscopes. The capsule cameras thus have provided the first real look inside a functioning small intestine.

The disposable camera is ingested by the patient and, as peristalsis carries the capsule on an eight-hour journey through the small intestine, it snaps thousands of images that are transmitted to a data recorder that the patient wears. Doctors review the images afterward.

"But there are lots of times when you have these abnormalities [in an image] and you're not really sure what you're seeing," Lebovitz said.

In one recent case, for instance, UPMC's Appasamy said the camera picked up what might have been an early tumor in one elderly patient. But the findings weren't clear and the patient ultimately decided against surgery to biopsy or remove the tumor.

In those cases, both doctors said, it would helpful to send down a swallowable camera that could be controlled and have it go to areas that need further study.

In addition to equipping the robot with biopsy capability, it also might be used to deliver anti-inflammatory or other medications. Lebovitz said that a robot equipped with a flashing light might even help surgeons find a diseased area that needs to be excised.

A number of problems remain to be solved. For instance, the small intestine is typically collapsed, so maneuvering through it might be difficult for a legged robot. And power already is limited for the capsule cameras; precious little additional power may be available for locomotion.

But if the gutbot proves feasible for the small intestine, other applications may await it in the colon. Though the colon can be visualized with a long, flexible colonoscope, the procedure is not a popular one. Sitti, Lebovitz and Appasamy suggested it may someday be possible to use a legged camera introduced through the anus as a substitute for traditional colonoscopy. They emphasized, however, that such an application is still years away.

For that matter, Sitti said, it may be possible to someday equip an intestinal robot to perform surgeries beyond just biopsies. But for now, developing a robot that could improve diagnosis of digestive tract disease is the immediate concern.

"It's really just a first step," he added.