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FORTUNE — The first generation of camera-equipped pills actually appeared more than a decade ago but were passive — you swallowed, waited, and hoped the digestive process did the rest. Today tiny tools are helping surgeons pull off mind-blowing procedures. Within a decade these three devices could even seek out maladies and stop them in their tracks.

Nanobots

The ultimate in-body robot is smaller than a blood cell. After being injected into a patient’s bloodstream, nanoparticles made out of human genetic material seek out harmful cells — cancer, for example — and deliver drugs.

Pinchers and clinchers

Skinny, millimeter-long tools made up of extremely small gears and pulleys navigate through blood vessels, grabbing and fusing together bits of tissue. Why? To make delicate repairs — on a live, beating pig heart in one recent trial.

Mini-assistants

Carrying cameras, scissors, forceps — even chemical-detecting sensors — these worm-like robots squirm through the body, assisting with surgeries or diagnoses. The newest models from Carnegie Mellon University have a diameter smaller than a dime’s.

A shorter version of this story appeared in the September 3, 2012 issue of Fortune.