A swimming robot -- inside your body
The Boston Globe describes the efforts of a Japanese-born scientist to develop new technologies for use in surgery. His last project is to build a swimming robot designed to explore the human gastrointestinal tract (GI tract) from esophagus to colon. This 2-centimeter long robot will have a swimming tail to deliver the energy picked from the outside and use it to steer it in the GI tract. It will also be able to send back images to the physicians and to deliver therapy. Coincidentally, the Philadelphia Inquirer is reporting about another medical robot helper able to crawl like an inchworm into your heart.
This second robot, the HeartLander, is designed by Cameron Riviere, an associate research professor at Carnegie Mellon University's Robotics Institute in Pittsburgh. But it's not an independen robot.
The device is inserted through a small incision in the chest and controlled with a wire tether by an external operator. Two suction-pad feet and a flexible midsection enable the device to move at about half a foot a minute. "It is not completely independent or detached, but can freely move with the beating heart," Riviere said. Just 6 millimeters high and 8 wide, the robot can squeeze into the space between the heart and its outer lining. Tiny holes on the feet create a vacuum that ensures HeartLander remains attached.
Now, let's move to the swimming robot designed by Nobuhiko Hata, technical director of image guided therapy at Brigham And Women's Hospital and a professor of radiology at Harvard Medical School. Here are his comments about a trip to Japan which led him to the design of this swimming robot.
"In Japan they're thinking seriously on integrating robots as partners" with human beings, he says. This cooperative philosophy inspired Hata to think about applying mechanical techniques to problems he had previously only been thinking about through computers. The result: "the swimming robot."
There are similar devices under development, but Hata's has the distinction of "swimming" -- using oscillations in the magnetic field of an MRI machine to power its fins. It will literally dart like a minnow through the body's cavities, taking images, and, perhaps, releasing chemicals or directing a tiny laser at the problem area. Hata's robot is still in the early stages of development, but this month he will present a paper on it at a radiologists' conference in Berlin.
In "Radiology and GI Imaging Close the Divide," Imaging Technology News gives more details about this active swimming endoscope. (Cristen C. Bolan, Imaging Technology News, April issue 2007)
The current capsule endoscope on the market is passive -- it moves down the GI tract starting with parastatic movement of the esophagus. The problem, according to Hata, is that you cannot drive the capsule toward suspicious lesions nor can you position it to do more precise scrutiny of a lesion. Hata believes that the solution to the problem is to develop an actively steerable endoscope, and, to this end, he is developing swimming micro-robots -- un-tethered endoscopes for transmitting images from inside the body.
"Our technology is unique in the sense that it swims. Others have developed an endoscope, rowing it through the GI tract, but we believe that a swimming tail is the most efficient way of delivering the energy from the outside and then converting it to a propulsion pulse to steer it in the GI tract," said Hata. The propulsion is inspired by a novel propulsion theory based on flagellar motion and is achieved by creating a traveling wave along a tail made of piezoelectric material decomposed into the natural modes of the beam. According to Dr. Hata, three individual waving tails, controlled by a magnetic field, are designed to swim in any direction.
Let's finish with Hata's philosophy, as reported by the Boston Globe: "On the day somebody closes my coffin, I want to count how many people I've saved. If it's more than one, then my presence was worthwhile." I could paraphrase this: if I've helped some readers of this blog, I would have been useful.
Sources: Andrew Rimas, The Boston Globe, May 7, 2007; Josh Goldstein, The Philadelphia Inquirer, May 7, 2007; and various websites
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