Connecting a human brain to a computer is as much a materials science problem as a biology one. What kind of interface is delicate enough not to damage nerve tissue, but resilient enough to last decades?

Researchers have come up with what they call a “stealthy neural interface” made from a single carbon fiber and coated with chemicals to make it resistant to proteins in the brain.

The new microthread electrode, designed to pick up signals from a single neuron as it fires, is only about 7 micrometers in diameter. That is the thinnest yet developed, and about 100 times as thin as the conventional metal electrodes widely used to study animal brains.

“We wanted to see if we could radically change implant technology,” says Takashi Kozai, a researcher at the University of Pittsburgh and the lead author on the paper, published today in the journal Nature Materials. “We want to see an electrode that lasts 70 years.”