Using hundreds of untethered grippers, each as small as a dust mote, engineers and physicians at Johns Hopkins University, Baltimore, MD, say they have devised a method to perform biopsies that could provide a more effective way to access narrow conduits in the body as well as find early signs of cancer or other diseases.

In two recent peer-reviewed journal articles, the team reported successful animal testing of the tiny tools, which require no batteries, wires, or tethers as they grab internal tissue samples. The sub-millimeter-sized devices are called “mu-grippers,” incorporating the Greek letter that represents the term for “micro.” Instead of relying on electric or pneumatic power, these star-shaped tools 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 the journal, Gastroenterology, the researchers described their use of mu-grippers to collect cells from the colon and esophagus of a pig, and earlier this year, they 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 the bile duct to retrieve tissue samples.

Mu-grippers, they say, can collect far more samples from many more locations than current biopsy methods. They provide the ability to do a large statistical sampling of tissue to draw a conclusion. In fact, they say they could deploy hundreds or even thousands of grippers to get more samples and a better idea of what kind of or whether a disease is present.

Although each mu-gripper can grab a much smaller tissue sample than larger biopsy tools, the researchers say each gripper can retrieve enough cells for effective microscopic inspection and genetic analysis.