Why It’s so Hard to Develop the Right Material for Brain Implants

via The Verge

The brain is soft and squishy, like “a swollen network of gooey gel.” Electronics, on the other hand, tend to be rigid. So designing a brain implant can be tricky, like sticking a plastic fork into a bowl of Jell-O and hoping the fork doesn’t move too much.

The first sensor was implanted into the brain of a paralyzed patient in 1998. The past 20 years have seen growing interest in brain-machine interfaces, which are brain implants that can record information from our neurons and also stimulate the neurons. Millions of dollars have been spent on developing this technology, from government-funded projects to Elon Musk’s startup NeuraLink. The possibilities are intriguing: help those with motor disabilities, treat depression, or, if you’re Musk, merge AI and human brains to replace language as we know it.

The Verge spoke with Christopher Bettinger, a materials scientist and biomedical engineer at Carnegie Mellon University, about the state of brain-machine implant research, obstacles that remain, and the new research material that could solve some of these design problems. (This research was recently published in the journal Advanced Functional Materials.)

What are some of the main challenges when it comes to brain-computer interfaces?

There’s a fundamental asymmetry between the devices that drive our information economy and the tissues in the nervous system. Your cellphone and your computer, for example, use electrons and pass them back and forth as the fundamental unit of information. Neurons, though, use ions like sodium and potassium. This matters because, to make a simple analogy, that means you need to translate the language. It just slows everything down, and raises questions of: how do you accelerate that translation? How do you harmonize those different languages?

The other issue is mechanics. The brain is this swollen network of gooey gel. To date, most interfaces have been these silicon-based technologies, [so it’s] like sticking a plastic fork into a bowl of Jell-O. These might work for a few days or weeks or even months. But eventually, they start to fail. And there’s “micro-motion artifacts,” or the small movements of the probe in the brain that can damage the tissue, lead to inflammation, or exacerbate scarring. It’s all natural biological reactions, but over time it leads to worse signal quality, and, eventually, the implant fails.

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