While electroencephalography (EEG) can provide a wealth of information on the electrical activity of an individual's brain, ...

Additionally, researchers tweaked the ink's formula and printed e-tattoo lines that run down to the base of the head from the electrodes to replace the wires used in a standard EEG test.

Alternatively, a cap with electrodes can be directly placed on the head. However ... known as an electronic tattoo, that is 30 micrometers thick — approximately half the width of a human ...

A standard EEG test requires electrodes that come with pitfalls. A spray-on ink, capable of carrying electrical signals, avoids some of those.