'Electronic' scalp tattoos could be next big thing in brain monitoring

Scientists have developed a new technology that can measure brain waves using electronic, temporary tattoos.

The researchers say the method could act as a quicker and more convenient way to monitor brain activity and diagnose neurological conditions, such as seizures, epilepsy and brain tumors, compared to traditional electroencephalogram (EEG) tests.

During an EEG test, technicians normally use rulers and pencils to mark up a person's head before gluing electrodes across the scalp. These electrodes are then connected via long wires to a machine that records brain activity. Alternatively, a cap with electrodes can be directly placed on the head.

However, this whole process is time-consuming and inconvenient, say the developers of the new technology. It generally takes around one to two hours to set up an EEG test, said co-developer Nanshu Lu, a professor of engineering at the University of Texas at Austin. The electrodes then need to be monitored about every two hours because the glue that attaches them to the scalp dries up, she told Live Science in an email.

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The new technology, on the other hand, uses a robot that is digitally programmed to jet ink made of conductive material onto specific positions on a person's scalp — saving both time and labor, say the researchers. Currently, this printing process still takes an hour as the team has to manually correct for a persons' head movements, Lu said. However, if future adaptive printing can be fully automated, the whole printing process can be done within 20 minutes, she added.

The ink then dries into a thin film, known as an electronic tattoo, that is 30 micrometers thick — approximately half the width of a human hair. Like regular EEG electrodes, these e-tattoos can then be used to detect changes in the electrical activity of the brain.

In a new study, published Monday (Dec. 2) in the journal Cell Biomaterials, the researchers tested the technology on five people with short hair to compare it to conventional EEG technology. They found that the e-tattoos were just as good at detecting brain waves as the conventional EEG electrodes that were placed next to them.

Furthermore, the e-tattoos stayed on the participants' heads and could record brain activity for at least a day, while the EEG electrodes began dropping off after six hours. Once measurements are made, e-tattoos can be simply scrubbed off using alcohol wipes or washed off using shampoo, Lu said. EEG electrode glue, on the other hand, is more difficult to get out of hair.

The ink formula can also be modified to create tattoo lines onto the scalp, meaning that the wires that connect the e-tattoos to a monitor are much shorter than they would be in a regular EEG test.

The researchers now need to determine if these e-tattoos work in patients with specific neurological conditions, as well as those with different lengths and types of hair, or skin allergies. They're also planning to invent a printer that can make an ink that doesn't rub off on a person's pillow as they sleep, Lu said. This could theoretically enable scientists to measure brain activity overnight, which may be useful for diagnosing things like sleep disorders.

In the future, the researchers also hope to embed wireless data transmitters in the e-tattoos to make the system fully portable.

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