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JUL/AUG 2013  

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Johns Hopkins team develops tiny surgical tools to perform biopsies

By using swarms of untethered grippers, each as small as a speck of dust, Johns Hopkins engineers and physicians say they have devised a new way to perform biopsies that could provide a more effective way to access narrow conduits in the body and detect early signs of cancer or other diseases.


Instead of relying on electric or pneumatic power, these star-shaped microgrippers, called mu-grippers, are autonomously activated by the body's heat, which causes their tiny "fingers" to close on clusters of cells. Because the tools also contain a magnetic material, they can be retrieved through an existing body opening via a magnetic catheter.

In two recent peer-reviewed journal articles, the team reported successful animal testing with the tiny tools, which don't require batteries, wires or tethers as they collect internal tissue samples.

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A “mu-gripper” near the opening of an endoscopic catheter. Image credit: Evin Gultepe, Gracias lab

In the April edition of Gastroenterology, the researchers described their use of the mu-grippers to collect cells from the colon and esophagus of a pig, which was selected because its intestinal tract is similar to that of humans. Earlier this year, the team members reported in the journal Advanced Materials that they had successfully inserted the mu-grippers through the mouth and stomach of a live animal and released them in a hard-to-access place, the bile duct, from which they obtained tissue samples.

"This is the first time that anyone has used a sub-millimeter-sized device—the size of a dust particle—to conduct a biopsy in a live animal," said David Gracias, an associate professor of chemical and biomolecular engineering at Johns Hopkins whose lab team developed the microgrippers. "That's a significant accomplishment. And because we can send the grippers in through natural orifices, it is an important advance in minimally invasive treatment and a step toward the ultimate goal of making surgical procedures noninvasive."

The advantage of the mu-grippers is that they could collect far more samples from many more locations, according to the researchers.

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