The most commonly tested brain implant is the Utah array — a hard silicon square with 100 tiny protruding needles. The needles are each about a millimeter long and have electrodes on their tips that record brain signals. But these rigid devices can scar nearby tissues, which over time can impair their ability to absorb. In contrast, one of Neuralink’s innovations is the flexible threads attached to its implant, fitted with more than 1,000 electrodes.
Neuralink is also trying to improve on existing BCIs that require clunky setups and invasive brain surgery; Instead, the company’s sewing-machine-like robot could install electrodes by punching them into the brain through a small hole in the skull. Also, the device transmits brain signals wirelessly, unlike most current BCIs, which rely on external cables connecting from a person’s head to a computer.
Neuralink has tested its prototype on pigs and monkeys, and in April 2021 the company released video of a macaque playing the video game Pong hands-free thanks to two brain implants the company installed in its brain. (The feat was accomplished by a person with a BCI 15 years ago.)
In a 2020 company update, pigs implanted with the coin-sized Neuralink device trotted onto a stage for Musk to demonstrate the implant’s safety as well as its ability to record neural activity from the pigs’ brains. (He described the device as “a Fitbit for your skull with tiny wires.”) One pig had an implant in its brain at the time of the demonstration, and another previously had one but was previously removed. Meanwhile, the pig’s brain signals were transmitted on a screen.
The company’s current implant, which is a quarter the size of a quarter, contains 1,000 channels that can record and stimulate nearby neurons. But on Wednesday, Neuralink employees said they are working on a next-generation chip with 4,098 channels in a chip of the same size.
Although Neuralink is the best-known, a handful of other companies are also working on brain implants, grappling with common issues like safety, longevity, and what they can achieve with the implant.
Two former Neuralink employees have started their own BCI companies. Last year, Science Corp was formed, led by former Neuralink President Max Hodax, and Precision Neuroscience, which was founded by Benjamin Rapoport, another original member of Musk’s team. In a Nov. 21 blog post on the company’s website, Science Corp employees revealed their concept for a neural interface aimed at restoring vision in people with retinitis pigmentosa and dry age-related macular degeneration, two forms of severe blindness that are not well treated can become options. According to the blog post, the company is working to prove safety data in animals.
Meanwhile, Precision Neuroscience is developing a thin, flexible brain implant for paralysis that sits on top of the brain and could be inserted through a small slit in the head, rather than drilling a hole in the skull. According to Rapoport, the company has tested its device on pigs and hopes to get the green light from the Food and Drug Administration to implant it in a human patient in 2023.