The group attached three robotic legs to a standard capsule camera and covered microscopic fibers on the adhesion pads with biocompatible silicone oil. The capsule robot is one centimeter in diameter and three centimeters in length, with 1.5-centimeter-long feet that open on demand and press into the surface of the tissue to increase friction and anchor the device, says Sitti. In a recent paper published in the Journal of Adhesion Science and Technology, Sitti showed that the oil increased adhesion up to 25 percent over a dry attempt on a smooth surface. On a slightly rough surface, the oily layer improved adhesion by almost 6 times. Recently, the team demonstrated that the capsule robot can successfully anchor on animal intestines in vitro, says Sitti, as well as on an animal esophagus.
“Clearly, a capsule that you can control in real time is going to be the next major advance for capsule-based systems,” says Schattner. “The current capsule technology is not controllable: you’re at the mercy of what the body is doing. The only thing you can do is image. You can’t do anything therapeutic.” Doctors have used the capsules to image the esophagus, colon, and–mainly–small intestine.
Sitti’s group is also mimicking gecko feet. Geckos have angled hairs on their feet that allow them to pull in one direction to adhere more securely, and in another direction to detach. “We made some angled fibers [where] in one direction friction is very high, and the other direction it’s low,” says Sitti. The group plans to put the angled fibers on the capsule robot in the future.