This man set the record for wearing a brain-computer interface

Because so few people are equipped with these devices, their longevity is still unknown. So far, the Utah array has lasted up to 10 years in monkeys. In Copeland’s case, his implants still work, but not as well for the first year or so after implantation, says Robert Gaunt, a biomedical engineer at the University of Pittsburgh and a member of Copeland’s research team. “The body is a very difficult place to put electronics and technical systems in,” says Gaunt. “It’s an aggressive environment and the body is always trying to get rid of these things.”

Implanted arrays can elicit an immune response in the nerve tissue surrounding the electrodes — the sharp probes that pierce the brain. Studies have shown that this inflammation can lead to reduced signal quality. And scar tissue can form around brain implants, also affecting their ability to pick up signals from nearby neurons. The less information a BCI can interpret from neurons, the less effective it is in performing its intended functions.

Scientists are trying to make implants last longer by experimenting with different types of materials. The Utah array is insulated with Parylene, a protective polymer coating used in the medical device industry for its stability and low moisture permeability. But it can corrode and crack over time, and other materials may prove more durable.

According to Florian Solzbacher, CEO of Blackrock Neurotech, which makes the Utah arrays, the company is testing one coated with a combination of parylene and silicon carbide, which has been used as an industrial material for more than 100 years. “We’ve seen lifespans on the lab bench that can reach up to 30 years, and we now have some preliminary data in animals,” he says. But the company has yet to implant it in humans, so the real test will be how human tissue responds to the new formulation.

More flexible electrodes could also help reduce scarring. Angle’s company, Paradromics, is developing an implant similar to the Utah array, but with thinner electrodes designed to disrupt tissue less.

Some researchers are trying softer materials that may integrate better with the brain than the rigid Utah array. A group at the Massachusetts Institute of Technology is experimenting with hydrogel coatings that are said to have elasticity very similar to that of the brain. University of Pennsylvania scientists are also growing “living” electrodes, hair-like microtissues made from neurons and nerve fibers grown from stem cells.

But these approaches also have disadvantages. “You can turn a rigid thing into a soft thing. But when you’re trying to put a very soft thing into another soft thing, it’s very difficult,” says Gaunt.

Another approach is to make the implants smaller and therefore less invasive. For example, researchers are testing neurogranules, tiny chips the size of a grain of sand that could hypothetically be scattered across the cortical surface. But nobody has tried to put them on a human brain; The system has only been tested on rodents that have had their skulls removed.

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