A better brain implant: Slim electrode cozies up to single neurons

A thin, flexible electrode developed at the University of Michigan is 10 times smaller than the nearest competition and could make long-term measurements of neural activity practical at last.

This kind of technology could eventually be used to send signals to prosthetic limbs, overcoming inflammation larger electrodes cause that damages both the brain and the electrodes.

The main problem that neurons have with electrodes is that they make terrible neighbors. In addition to being enormous compared to the neurons, they are stiff and tend to rub nearby cells the wrong way. The resident immune cells spot the foreigner and attack, inflaming the brain tissue and blocking communication between the electrode and the cells.

The new electrode developed by the teams of Daryl Kipke, a professor of biomedical engineering, Joerg Lahann, a professor of chemical engineering, and Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering, is unobtrusive and even friendly in comparison. It is a thread of highly conductive carbon fiber, coated in plastic to block out signals from other neurons. The conductive gel pad at the end cozies up to soft cell membranes, and that close connection means the signals from brain cells come in much clearer.

"It’s a huge step forward," Kotov said. "This electrode is about seven microns in diameter, or 0.007 millimeters, and its closest competitor is about 25 to 100 microns."

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