Neuro biotracer chips were small computer chips that could be placed inside someone's brain for a variety of purposes. In many ways, it acts as a parasite -- although it is a piece of technology rather than a living organism.
The chips perform a variety of tasks -- from simply allowing the person whose head contains the chip to be tracked to preserving knowledge that may later be retrieved from the chip. These chips also create neural clones that can influence or control the behavior of the person in question.
Scorpius implanted one of these chips into the brain of John Crichton while the human was on the Aurora Chair. The chip was eventually removed, though parts of Crichton's brain tissue were seriously damaged and needed further medical attention to repair.
The chips are fragile, and can be completely destroyed if they overheat. As such, these chips are utterly useless when it comes to Scarrans.
Neuro biotracer chips are derived from Farscape.