Self-Directed Microspiders

Sounds more than a little creepy to me, but advances in medical procedures may eventually depend on them:

Next, Sen hopes to develop versions of these tiny aquatic spiders that run on chemicals readily available in the body, such as glucose. In the future, more sophisticated microspiders attached to nanobots that detect chemicals secreted by damaged tissue could swim through the bloodstream, weaving a medical glue to help heal tears in vessel walls. Decorated with other micromachines and enzymes, they could swim through the circulatory system scouting out tumours, scouring plaque from vessel walls and helping the immune system battle infections.