September 26, 2015

Very recently, we reported on 3D printed ‘microfish’ robots that can be injected directly into our blood to perform complex medical tasks. Now, yet another aquatic creature has inspired scientists and 3D engineers within the medical community. A team from the Institute of Precision Engineering at the Chinese University of Hong Kong as developed 3D printed tadpole-like devices that can improve diagnosis of various cancers by entering the patient’s stomach and wirelessly transmitting images of what it sees.

A traditional procedure for diagnosing cancers of the gastrointestinal (GI) tract, which rank as the second most prevalent among all types of cancers in the world, is endoscopy, wherein a long, flexible tube with a light and camera attached to its end passes through a person’s digestive system. This can be done either through the mouth and back of the throat, as in gastropy, or through the anus, as in colonoscopy. By observing the transmitted video on a TV monitor, doctors can get a first-hand view of the patient’s organs and assess the damage. While the procedure has been invaluable in diagnosing stomach, intestinal, esophagus and colon cancers, it requires a great deal of skill on behalf of the doctor, and can be uncomfortable, painful, and stressful for the patient—not to mention prohibitively expensive.

The new 3D printed device, called the Tadpole Endoscope (TE), is a reliable and relatively non-invasive solution that could improve the very way we diagnose cancers. Developed to be swallowed just like a large pill (it is a bit bigger than a small coin), the TE begins to work immediately and can be remotely controlled all the way through the patient’s digestive track.

Inspired by the mechanics that move tadpoles underwater, the TE’s drive unit is constructed with two permanent magnets with opposing polarities and a magnetic coil. When energized, the coil generates a repulsive and attractive force that can propel the TE, mimicking tadpoles in nature. While similar devices, known as wireless capsule endoscopes, have been created in the past, the TE is notable for its soft tail, which allows it to be deftly guided around the entire stomach by the doctor, and the ingeniously 3D printed shell, which houses control electronics and the video camera holder. According to the engineers, who published their breakthrough research in the journal HKIE Transactions, the maximum swimming speed can reach 12.5 mm/s and the minimum turning radius is 25 mm in the stomach.

The result is more comprehensive imaging and accurate location information relative to where the problems are inside the patient’s body—all invaluable information when it comes to cancer diagnosis. Once the stomach has been thoroughly checked, the device ‘swims’ into the lower GI tract aided by natural peristaltic action—that is, the wave-like muscle contractions that move food along the digestive tract—and can continue to gather and transmit images from there.

Experiments in a stomach model.

Depending on how the patient is seated, the doctor can view different parts of the stomach

Ex vivo testing in a pig stomach.

So far, the Tadpole Endoscope has been tested in an artificial stomach as well as in a pig stomach in order to assess the feasibility of the propulsion model. Though in both cases the imaging system had not yet been installed, the researchers believe that the model can move onto the next stage of experiments and eventually be successfully implemented in medical applications.



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