Florian Solzbacher, co-founder and chairman of Blackrock Neurotech, which manufactures the Utah arrays, says the company is testing one that’s coated with a combination of parylene and silicon carbide, which has been around for more than 100 years as an industrial material. “We’ve seen lifetimes on the benchtop that can reach up to 30 years, and we’ve got some preliminary data in animals right now,” he says. But the company has yet to implant it in people, so the real test will be how human tissue reacts to the new formulation.
Making electrodes more flexible could also help reduce scarring. Angle’s company Paradromics is developing an implant similar to the Utah array, but with thinner electrodes intended to be less disruptive to tissue.
Some researchers are trying out softer materials that may be able to better integrate into the brain than the rigid Utah array. One group, at the Massachusetts Institute of Technology, is experimenting with hydrogel coatings designed to have an elasticity very similar to that of the brain. Scientists at the University of Pennsylvania are also growing “living” electrodes, hairlike microtissues made of neurons and nerve fibers grown from stem cells.
But these approaches have downsides, too. “You can get a rigid thing into a soft thing. But if you’re trying to put a very soft thing into another soft thing, that’s very hard,” Gaunt says.
Another approach is to make the implants smaller, and therefore less invasive. For instance, researchers are testing neurograins, tiny chips the size of a grain of sand that could hypothetically be sprinkled across the cortical surface. But no one has tried dispersing them on a human brain; the system has only been tested in rodents that had their skulls removed.
Some research participants have had their Utah arrays taken out and replaced, but multiple surgeries aren’t ideal, because each one carries a risk of infection or bleeding at the implant site. Gaunt says surgeons probably wouldn’t place a new implant in the exact same place as an old one, especially if there’s scarring in that area. But making sure that a replacement is put in the right spot is important because implants in the wrong place could impair the function of the BCI.
Gaunt says it would be better for the external BCI components—the processors or software, for instance—to be upgradable, so that patients wouldn’t have to undergo multiple surgeries.
But in fact, an external part of most BCI systems is actually one of the biggest risks for brain implants. The pedestal that sits atop the skull can cause infection, but its presence is necessary to connect the implanted array to the external computer. For now, Copeland and other research participants have to get plugged into the system via their head pedestals to use their BCIs. (Researchers are working on getting rid of the cables.) For Copeland, it’s a mild annoyance in exchange for getting to do the things he can do with his BCI—although he hopes future systems will be wireless and give paralyzed people an even broader range of abilities.
Given the unknowns of BCI longevity, Copeland knows his implant could stop working some day. But he tries not to worry about it. “I’m super chill about most things. I just go with the flow,” he says. That said, he wouldn’t turn down an upgrade: “In five or 10 years, if there is something that would have significant improvements, I would do the surgery again and just go for it.”