What is Nano robotics theory for engineering?

Nanorobotics is an emerging technology field creating machines or robots whose components are at or near the scale of a nanometer. We know 1 nanometer = 10 invers 9 meter.
According to Richard Feynman, it was his former graduate student and collaborator Albert Hibbs who originally suggested to him the idea of a medical use for Feynman's theoretical micro-machines (see biological machine). Hibbs suggested that certain repair machines might one day be reduced in size to the point that it would, in theory, be possible to "swallow the surgeon". The idea was incorporated into Feynman's 1959 essay There's Plenty of Room at the Bottom.