Health & Environment: ...And Will They Go Inside Us?

Given the promise of nanotechnology, it's a safe bet

Imagine an army of tiny robots, each no bigger than a bacterium, swimming through your bloodstream. One platoon takes continuous readings of blood pressure in different parts of your body; another monitors cholesterol; still others measure blood sugar, hormone levels, incipient arterial blockages and immune-system activity.

Such are the dreams of the nanotechnologists, engineers at places like M.I.T., Princeton University and Carnegie Mellon, who are already redefining the meaning of the word miniature. The prefix nano- refers to a billionth part of a unit--the size range these visionaries are talking about. Already, nanotechnologists have built gears and rotors far thinner...