Elon Musk. TED

Tesla CEO Elon Musk has raised $27 million for Neuralink, a company he created last year to link human brains with computers.

Neuralink has sold $27 million worth of equity out of a total offering of $100 million, according to a document published by the SEC on Friday. The form lists 12 unnamed investors and says that equity was first sold on August 15, 2017.

Despite the filed paperwork, Musk tweeted on Friday that "Neuralink is not seeking investors," which suggests that he may be significantly contributing to the funding himself or has already locked in others backers. The paperwork lists Jared Birchall as Neuralink's president.

Representatives for Musk and Neuralink didn't respond to requests for comment.

Musk started Neuralink last summer to link the human brain with computers by creating micron-sized devices to be surgically implanted into the brain. The startup is aiming to bring to market a product that helps with certain severe brain injuries due to stroke and cancer lesion in about four years.

Musk has described the need to create a "neural lace" device that's capable of supercharging the human brain. He has said that such a device would help humans combat the existential threat of artificially intelligent super-computers. Such a device would also allow humans to engage in "consensual telepathy."

Neuralink's website currently lists 8 job openings, including a chip designer, mechanical engineer, and a few software engineers.

Neuralink is Musk's fourth company. He is also the CEO of Tesla, SpaceX, and OpenAI, a non-profit AI research company. He also leads a tunneling startup called The Boring Company, which started as an offshoot of SpaceX.