Revolutionary e‑tattoos promise faster, easier EEG testing

EEG testing (electroencephalography) involves measuring electrical activity in the brain through electrodes placed on the scalp. It helps diagnose neurological disorders such as epilepsy, tumours, and injuries resulting from strokes or traumatic blows to the head. Scientists have now developed new technology that helps study brain waves using temporary electronic tattoos. Once applied, these tattoo inks form a thin layer that is about half the thickness of a human hair and, similar to standard EEG electrodes, detect changes in the brain's electrical activity.

Until now, technicians used a ruler and pencil to mark spots on the patient's head before attaching electrodes to the scalp. Then, these electrodes are connected with long wires to a device recording brain activity. Alternatively, a cap with electrodes can be placed directly on the head. However, this entire process is time-consuming and inconvenient. The new solution cuts the time in half right from the start.

The technology employs a digitally programmed robot to deposit conductive ink onto precise locations on the scalp, streamlining the process and reducing effort, explained Nanshu Lu, one of the solution's co-developers and an engineering professor at the University of Texas at Austin, during an interview with New Scientist.

A computer program was created, which prepares an individual tattoo design each time based on a three-dimensional scan of the scalp. Then, a printer, controlled by a robotic arm, applies the ink directly onto the scalp. Two different types of ink are used: one for the electrodes sensing the brain's signals and another for connections running towards the neck. There, wires physically transmit signals to a small device recording the data.

In a new study published on 2nd December in the journal "Cell Biomaterials", this technology was used on five people with short hair to compare it with conventional EEG technology. It was found that the e-tattoos were equally effective in detecting brain waves as traditional EEG electrodes placed next to them.

E-tattoos adhered to participants' heads and successfully recorded brain activity for a full day, whereas EEG electrodes started to loosen after six hours. Once measurements were completed, the e-tattoos could be easily removed using alcohol wipes or shampoo. In contrast, removing bisacryl, the adhesive for EEG electrodes, from hair proved significantly more challenging, as noted by a professor from the University of Texas at Austin.

Researchers now need to determine whether e-tattoos work for patients with specific neurological disorders, people with various hair lengths and types, or people with skin allergies. They also plan to create a printer that produces ink that won't rub off on a pillow during sleep, explained Lu. This would allow scientists to monitor brain activity at night, which could be useful in diagnosing sleep disorders. In the future, scientists hope to embed wireless data transmitters in e-tattoos, making the system fully portable.