Temporary tattoo printed immediately on the scalp provides simple, hair-friendly resolution for measuring brainwaves

For the primary time, scientists have invented a liquid ink that medical doctors can print onto a affected person’s scalp to measure mind exercise. The know-how, introduced December 2 within the journal Cell Biomaterials, provides a promising different to the cumbersome course of at present used for monitoring brainwaves and diagnosing neurological situations. It additionally has the potential to reinforce non-invasive brain-computer interface purposes.

“Our improvements in sensor design, biocompatible ink, and high-speed printing pave the way in which for future on-body manufacturing of digital tattoo sensors, with broad purposes each inside and past scientific settings,” says Nanshu Lu, the paper’s co-corresponding writer on the University of Texas at Austin.

Electroencephalography (EEG) is a vital software for diagnosing quite a lot of neurological situations, together with seizures, mind tumors, epilepsy, and mind accidents. During a conventional EEG take a look at, technicians measure the affected person’s scalp with rulers and pencils, marking over a dozen spots the place they’ll glue on electrodes, that are linked to a data-collection machine by way of lengthy wires to observe the affected person’s mind exercise. This setup is time consuming and cumbersome, and it may be uncomfortable for a lot of sufferers, who should sit via the EEG take a look at for hours.

Lu and her crew have been pioneering the event of small sensors that monitor bodily alerts from the floor of human pores and skin, a know-how referred to as digital tattoos, or e-tattoos. Scientists have utilized e-tattoos to the chest to measure coronary heart actions, on muscle groups to measure how fatigued they’re, and even underneath the armpit to measure elements of sweat.

In the previous, e-tattoos had been often printed on a skinny layer of adhesive materials earlier than being transferred onto the pores and skin, however this was solely efficient on hairless areas.

“Designing supplies which are suitable with bushy pores and skin has been a persistent problem in e-tattoo know-how,” Lu says.

To overcome this, the crew designed a sort of liquid ink manufactured from conductive polymers. The ink can circulation via hair to succeed in the scalp, and as soon as dried, it really works as a thin-film sensor, choosing up mind exercise via the scalp.

Using a pc algorithm, the researchers can design the spots for EEG electrodes on the affected person’s scalp. Then, they use a digitally managed inkjet printer to spray a skinny layer of the e-tattoo ink on to the spots. The course of is fast, requires no contact, and causes no discomfort in sufferers, the researchers mentioned.

The crew printed e-tattoo electrodes onto the scalps of 5 members with quick hair. They additionally hooked up typical EEG electrodes subsequent to the e-tattoos. The crew discovered that the e-tattoos carried out comparably nicely at detecting brainwaves with minimal noise.

After six hours, the gel on the traditional electrodes began to dry out. Over a 3rd of those electrodes failed to choose up any sign, though most the remaining electrodes had decreased contact with the pores and skin, leading to much less correct sign detection. The e-tattoo electrodes, alternatively, confirmed secure connectivity for at the very least 24 hours.

Additionally, researchers tweaked the ink’s components and printed e-tattoo strains that run right down to the bottom of the pinnacle from the electrodes to switch the wires utilized in an ordinary EEG take a look at.

“This tweak allowed the printed wires to conduct alerts with out choosing up new alerts alongside the way in which,” says co-corresponding writer Ximin He of the University of California, Los Angeles.

The crew then hooked up a lot shorter bodily wires between the tattoos to a small gadget that collects brainwave knowledge. The crew mentioned that sooner or later, they plan to embed wi-fi knowledge transmitters within the e-tattoos to attain a totally wi-fi EEG course of.

“Our examine can doubtlessly revolutionize the way in which non-invasive brain-computer interface units are designed,” says co-corresponding writer José Millán of the University of Texas at Austin.

Brain-computer interface units work by recording mind actions related to a perform, resembling speech or motion, and use them to regulate an exterior gadget with out having to maneuver a muscle.

Currently, these units typically contain a big headset that’s cumbersome to make use of. E-tattoos have the potential to switch the exterior gadget and print the electronics immediately onto a affected person’s head, making brain-computer interface know-how extra accessible, Millán says.