Then, their breakthrough came in the form of a new kind of liquid ink made from conductive polymers. The ink flows effortlessly through hair to reach the scalp, where it dries into a thin, flexible film. Once in place, the tattoo acts as a sensor, picking up brain signals with precision.
The process is remarkably simple. Researchers map out the electrode locations using a computer and then use a specialized inkjet printer to spray the liquid ink onto the scalp. Within minutes, the ink dries, forming a lightweight, unobtrusive tattoo. No discomfort; no glue; no wires.