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Neuroscience

First-of-Its-Kind Digital Scalp Tattoo Reads Brain Activity

New e-tattoos may disrupt brain-computer interfaces and precision neuroscience.

Source: Alexandra_Koch/Pixabay
Source: Alexandra_Koch/Pixabay

Brain monitoring is getting more personal. Scientists recently published a study in Cell Biomaterials showcasing an electronic tattoo printed directly on the scalp that is capable of monitoring brain activity noninvasively with a stable connectivity of 24 hours or longer—a breakthrough neurotechnology that may be a game-changer for precision medicine, neuroscience, and noninvasive brain-computer interfaces (BCIs).

“Our technique is the first to produce ultrathin e-tattoos directly on human skin for electrophysiology data acquisition despite hairs,” reported the trio of co-corresponding authors Nanshu Lu and José Millán of the University of Texas at Austin and Ximin He at the University of California, Los Angeles, along with a team of researchers.

The scientists developed a self-drying, skin-conforming, ultrathin, electronic scalp temporary tattoo that is printed digitally directly onto the head and personalized based on the unique contours and shape of an individual’s scalp. It is printed via a microjet nozzle without any contact or needles.

The researchers report that their method is the first to make ultrathin electronic tattoos directly on human skin—hairs and all. The specialized biocompatible ink can dry and spontaneously form a film at room temperature in just 12 minutes. Additionally, it sticks much better to the skin than other electronic tattoos that were transferred versus printed directly on the skin.

Prior to printing, scanning is done using a three-dimensional scanning app called ScandyPro running on an iPhone 13 that has been affixed on a five-axis robot that moves around the participant’s head. The coordinates for the electrodes are set using MeshEEG, an open-source function in MATLAB.

“These e-tattoos are electrically conductive and mechanically, as well as physiologically, unnoticeable, offering full-head, high-fidelity, long-term, and comfortable EEG recording capabilities without the need for labor-intensive and short-lived wet-gel electrodes, as well as cumbersome cables and caps,” wrote the scientists.

Electroencephalograms measure the electrical activity in the brain via metal electrode discs attached to the scalp. The worldwide market size for traditional EEG devices was USD 1.2 billion in 2023 and is expected to grow at a compound annual growth rate of 10.36% during 2024-2030 to reach USD 2.39 billion by 2030, according to Grand View Research.

Clinicians use EEGs to help diagnose stroke, certain psychoses, narcolepsy, epilepsy, brain tumors, brain inflammation, Alzheimer’s disease, drug intoxication, brain damage, coma status, brain death, Parkinson’s disease, neurological disorders, Creutzfeldt-Jakob disease, head injuries, encephalopathy, and other purposes such as monitoring brain blood flow during medical procedures and surgeries.

“This innovation significantly expands the potential applications of e-tattoos for EEG by solving many long-standing challenges,” wrote the researchers.

To evaluate the performance of their on-scalp printed electrodes, or e-tattoo, versus traditional commercial wet-gel electrodes, the team measured five study participants for error-related potential and motor imagery, which are two widely used brain-computer interface markers.

The scientists found that their tattooed electrodes not only performed on par with standard wet-gel electrodes, but also performed consistently over multiple sessions and increased electrode lifespan by six or more hours.

Compared to existing electroencephalography systems, their temporary electronic tattoo is more comfortable to wear, faster to install, and has higher adhesion, according to the scientists. The on-scalp printing of the electrodes is faster to set up than commercial EEG devices. In this study, it took less than 15 minutes to perform a three-dimensional head scan and print ten electrodes on the scalp. To calibrate for head movements, it takes five more minutes per movement. The printable electrodes are temporary tattoos that can easily be removed with soap or alcohol.

According to the scientists, their innovative technology could be used for purposes beyond brain activity monitoring and recording to include other internal organs for stimulation, rehabilitation, cardiac monitoring, skull monitoring, assistance in wound healing, regeneration of bone or tissue, and performance training. The researchers say that their electronic tattoo solution may be used for more than just brain-computer interfaces and has potential for a variety of human-machine interfaces, including electrocorticography (ECoG) recordings, electrocardiograms (ECGs), transcutaneous electrical nerve stimulation (TENS), and electromyography (EMG).

“It marks a new chapter in neurotechnology, emphasizing customization and accuracy, enhancing patient well-being, and minimizing healthcare labor,” the team of researchers concluded.

Copyright © 2024 Cami Rosso All rights reserved.

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