Temporary printable tattoos could be the future of EEGs

Eggheads in the US are said to have created an easier, faster, and just-as-reliable but much cooler way to measure brain activity than the bulky, wire-ridden caps used today: Printable, temporary "e-tattoos."

Brain activity is measured with electroencephalograms (EEGs), common tests used to help diagnose conditions such as epilepsy, sleep disorders, and brain injuries. While noninvasive, these tests can be cumbersome for patients, as setting up an EEG cap typically requires significant time to ensure proper fit. Even then they only work reliably for a couple of hours before conductive gel must to be reapplied.

In a paper published this week, a group of scientists from the University of Texas at Austin and University of California, Los Angeles claimed their printed EEG technique could eliminate many of those issues.

"The holy grail for EEG is a sensor that patients can wear for long periods of time, outside the clinical setting and without the need for constant maintenance," UT Austin professor Nanshu Lu, one of the project's researchers, said. "What we've developed opens the door for more mobile EEG sensing."

Lu and the team's e-tattoo system places electrodes and interconnects made of biocompatible ink directly onto the skin. The ink mesh is made by a five-axis robot, based on a 3D scan of a patient’s head, using algorithm developed for the purpose.

"In our study, 3D head scanning and printing of ten electrodes can be completed within about 15 min," the researchers noted in their paper. The whole process can take as little as 15 minutes. There is one caveat: Patients must remain extremely still.

"Head movements require additional calibration to update the coordinates of the landmarks, adding an extra five min per movement," the team said, adding that they hope to add visual tracking systems on the printer so that it can more easily account for patient twitches.

Once dry, the stretchable, conductive ink (which can even be printed over some short haircuts) is just half the thickness of a human hair, and is able to record brain activity for more than 24 hours with "sufficient and stable conductivity."

Once the scan is done, the e-tattoos can be removed easily with soap and water or an alcohol wipe.

Bonus: They look kinda rad, too

According to the research team, the e-tattoos have a signal quality that's just as good as wet gel electrodes – the gold standard for EEGs – while also offering improved comfort and longer continuous usability.

Youtube Video

All that and some sick-looking scalp tattoos – as you can see in the provided video above – what's not to love?

For starters, this technique won’t work well – or perhaps at all – on longer-haired individuals. Lu told the University of Texas that fixing that is next on the team's to-do list, and that robotic fingers or combs could be incorporated into the printer to separate hair in target areas.

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And while the printed e-tattoos may maintain stable conductivity for longer time than wet gel electrodes, there's still a friction issue: They're not yet a good fit for sleep monitoring because they tend to rub off while a sleeper tosses and turns.

Nonetheless, "e-tattoos for EEG [solve] many long-standing challenges," the team concluded. "It marks a new chapter in neurotechnology, emphasizing customization and accuracy, enhancing patient well-being, and minimizing healthcare labor."

Whether and when the technology will be commercialized isn't clear – we've asked, but haven't heard received a reply at the time of publication. ®