This robotic tank will crawl through your gut

Endoculus is a miniature robotic that can drive through your intestines on treads, streaming video and grabbing tissue samples with its electromechanical forceps. Developed by University of Colorado engineers, Edoculus or its descendants could someday replace the tubular scopes that physicians snake up our rectums during a colonoscopy. Evan Ackerman writes in IEEE Spectrum:

Endoculus gets around with four sets of treads, angled to provide better traction against the curved walls of your gut. The treads are micropillared, or covered with small nubs, which helps it deal with all your "slippery colon mucosa." Designing the robot was particularly tricky because of the severe constraints on the overall size of the device, which is just 3 cm wide and 2.3 cm high. In order to cram the two motors required for full control, they had to be arranged parallel to the treads, resulting in a fairly complex system of 3D printed worm gears. And to make the robot actually useful, it includes a camera, LED lights, tubes for injecting air and water, and a tool port that can accommodate endoscopy instruments like forceps and snares to retrieve tissue samples.

So far, Endoculus has spent some time inside of a live pig, although it wasn't able to get that far since pig intestines are smaller than human intestines, and because apparently the pig intestine is spiraled somehow. The pig (and the robot) both came out fine. A (presumably different) pig then provided some intestine that was expanded to human-intestine size, inside of which Endoculus did much better, and was able to zip along at up to 40 mm/s without causing any damage. Personally, I'm not sure I'd want a robot to explore my intestine at a speed much higher than that.

"Novel Optimization-Based Design and Surgical Evaluation of a Treaded Robotic Capsule Colonoscope" (ICRA 2020)