magnetic capsule endoscope
The size of a large pill, the magnetic microswimmer will travel at several millimeters per second through your intestine while looking for cancer.

For years medicine has struggled to kill off all the little parasites swimming inside the human body. Now they're ready to add their own. Researchers from Tel Aviv University in Israel and Brigham & Women's Hospital in Boston have collaborated to create a robot that will be able to swim through the intestines. The size of a large pill, the “microswimmer” is powered by the strong magnetic fields generated by an MRI machine. A tail measuring 20mm x 5mm made of copper and flexible polymer vibrates due to the magnets and propels the little microrobot through the gut. Still in early testing, the magnetic microswimmer has been shown to maneuver well in a water tank. Eventually its creators hope that the robot will be able to quickly explore the intestines, sending back pictures to diagnosticians, and helping detect the early stages of cancer. As disturbing as it sounds to have a robot doing laps in your colon, such a device could save the lives of millions of people in the years ahead.

Current methods for detecting gastrointestinal cancer rely on various forms of endoscopy. For the better part of the last century, doctors have been able to insert a camera into the colon to detect precancerous or cancerous growths. More modern forms of detection include “capsule endoscopy” where a pill-sized camera is swallowed and pictures taken every half second or so until the device is passed. Even such improved forms of endoscopy, however, have their limitations. A swallowed pill is essentially at the mercy of the movements of the GI tract.

Not so with the microswimmer. Developed by Gabor Kosa (TAU), Peter Jakab (B&W) and their colleagues, the tiny robot is powered and propelled by magnetic fields. As explained in the recent paper published in Biomedical Microdevices, 3T MRI machines are able to get the little device moving at speeds of several millimeters per second – more than adequate for this type of endoscopy. With such controlled movement, doctors would be able to aim the microswimmer towards different portions of the GI tract depending on the needs for each patient. Part of the ingenuity of the microswimmer is its reliance upon the MRI machine. Rather than worry about embedding large power supplies or propulsion systems that would make the device untenable, they can instead rely upon an instrument that is nearly ubiquitous in larger modern hospitals. Furthermore, the copper and polymer tail hinders MRI scans very little, leaving just a modest shadow on the image.

As imaging technology continues to shrink, engineers are creating ever smaller and more versatile cameras. Some are so miniscule they can fit on the tips of wires, others contain onboard legs that can be used to crawl through the GI tract, and now Kosa, Jakab and the rest of their team have even introduced a swimming version. Taken collectively these devices suggest that in the near future doctors will be able to image the interior of the body at will. Eventually, such micro-explorers may even be able to reside inside humans on a permanent basis. Not everything that swims in your gut is bad for you.

[image via American Friends of Tel Aviv University and taken at Brigham and Women's Hospital]
[source: Kosa et al Biomedical Microdevices 2011, Kosa et al Robotics and Automation 2008]