Electrode
A conductor that carries electrical signals in or out. In a brain-computer interface it means the fine needles or small contacts that pick up the very weak electricity produced by nerve cells.
An active nerve cell causes a tiny change in voltage around it. The closer an electrode sits to the cells, the finer the signal it picks up, approaching that of single cells. The Utah array, developed at the University of Utah in the 1990s with 100 needles on a chip about 4 mm square, became the standard for brain-computer interface research with implants in people[1].
More electrodes mean more information read at once. In 2019 Neuralink described a design that places more than a thousand electrodes on flexible threads thinner than a hair, inserted into the brain by a purpose-built robot[2]. Electrodes that penetrate the brain, however, demand major surgery, and over time scar-like tissue forms around them and weakens the signal. The Stentrode, which sits inside a blood vessel, settles for 16 electrodes in exchange for avoiding open-skull surgery.
Related terms
- Brain-computer interfaceTechnology that reads the brain's electrical signals and turns them into control of a computer or machine. Abbreviated BCI.
- StentrodeA device that mounts electrodes on a stent — a mesh tube used to hold blood vessels open — and delivers it through the neck to a vein near the brain, reading brain signals through the vessel wall.
- BiocompatibilityThe ability of a material or device placed in the body to keep doing its job without causing harm or rejection.
Sources
- E. M. Maynard, C. T. Nordhausen, R. A. Normann, “The Utah Intracortical Electrode Array: A recording structure for potential brain-computer interfaces,” Electroencephalogr. Clin. Neurophysiol. 102, 228–239 (1997).
- E. Musk, Neuralink, “An Integrated Brain-Machine Interface Platform With Thousands of Channels,” J. Med. Internet Res. 21, e16194 (2019).