Picobots

The term picobot and related words (picites, picotech, etc.) are logically derived from "nanotech" and its related terms.

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As nanotech is the technology relating to human-made devices operating near the scale of a nanometer (10^-9 meters, or one-one billionth of a meter), so picotech refers to similar but smaller devices, presumed to operate around the scale of a picometer (10^-12, or one-one trillionth of a meter).

To get a better idea of the scale, consider that a hydrogen atom is only about 50 picometers in diameter. Picotechnology, if it existed, would be operating on an atomic or even subatomic level. Given that nanotechnology and nanites are still largely in the hypothetical/earliest experimental stage, picotech, picites, and the like, which would be roughly one thousand times smaller, are safely lodged in the realm of science fiction--for now.

See also:

Metric prefixes
Nanorobotics