
The Bord woud “assimilate” humans by using a Nanoprobes which are microscopic machines that inhabit a Borg's body, bloodstream, and many cybernetic implants. The probes perform the function of maintaining the Borg cybernetic systems. They generate new technology inside a Borg when needed as well as protecting them from many forms of disease and virus. Borg nanoprobes, each about the size of a human red blood cell, travel through the victim's bloodstream and latch on to individual cells. The nanoprobes rewrite the cellular DNA, altering the victim's biochemistry, and eventually form larger, more complicated structures and networks within the body such as electrical pathways, processing and data storage nodes, and ultimately prosthetic devices that spring forth from the skin. (1)
The idea is microscopic technology is interesting and isn’t completely science fiction. This is every similar to the technology of nanobots, which would allow microscopic particles to flow through the bloodstream and repair DNA.
These ideas follow along a similar line as the High evolutionary- whereby The Borg race, which essentially evolves humans into machines. This idea was also utilised within the Transformer series, whereby machines were transformed into killer robots.
Sources used within this post
(1) http://en.wikipedia.org/wiki/Borg_(Star_Trek)