Jonathan Raa | Nurphoto | Getty ImagesElon Musk's health tech company Neuralink labeled itself a "small disadvantaged business" in a federal filing with the U.S. Small Business Administration, shortly before a financing round valued the company at $9 billion.Neuralink is developing a brain-computer interface (BCI) system, with an initial aim to help people with severe paralysis regain some independence. BCI technology broadly can translate a person's brain signals into commands that allow them t...