For the first time, scientists have invented a liquid ink that doctors can print onto a patient’s scalp to measure brain activity.
Using a computer algorithm, the researchers can design the spots for EEG electrodes on the patient’s scalp.
Then, they use a digitally controlled inkjet printer to spray a thin layer of the e-tattoo ink on to the spots.
The team printed e-tattoo electrodes onto the scalps of five participants with short hair.
The e-tattoo electrodes, on the other hand, showed stable connectivity for at least 24 hours.
Doctors can now measure brain activity by printing a liquid ink onto a patient’s scalp for the first time thanks to scientific advancements. The technology, which was published in the journal Cell Biomaterials on December 2, presents a viable substitute for the laborious method currently employed for neurological condition diagnosis and brainwave monitoring. It might also improve applications for non-invasive brain-computer interfaces.
The paper’s co-corresponding author, Nanshu Lu of the University of Texas at Austin, states, “Our advancements in sensor design, biocompatible ink, and high-speed printing pave the way for future on-body manufacturing of electronic tattoo sensors, with broad applications both within and beyond clinical settings.”.
Many neurological disorders, such as seizures, brain tumors, epilepsy, and brain injuries, can be diagnosed with electroencephalography (EEG). In order to measure the patient’s brain activity, technicians use rulers and pencils to measure the patient’s scalp. They mark more than a dozen spots on the scalp where electrodes will be glued. The electrodes are connected to a data-collection device via lengthy wires. With hours of sitting through the EEG test, this setup is laborious and time-consuming, and many patients may find it uncomfortable.
Electronic tattoos, or e-tattoos, are a new technology that Lu and her team have been leading the way in developing. These tiny sensors track body signals from the surface of human skin. E-tattoos have been used by researchers to measure heart activity on the chest, muscle fatigue, and even sweat components under the armpit.
Before being applied to the skin, e-tattoos were typically printed on a thin layer of adhesive, but this worked best on areas of the body without hair.
One of the ongoing challenges in e-tattoo technology, according to Lu, has been creating materials that work with hairy skin.
The group created a conductive polymer-based liquid ink type to get around this. When the ink dries, it functions as a thin-film sensor that detects brain activity through the scalp after running through hair.
The researchers can design the patient’s scalp’s EEG electrode locations using a computer algorithm. They then apply a thin coating of the e-tattoo ink to the areas using a digitally controlled inkjet printer. According to the researchers, the procedure is quick, doesn’t involve any contact, and doesn’t make patients uncomfortable.
Five participants had short hair, and the team printed e-tattoo electrodes onto their scalps. Beside the e-tattoos, they also affixed standard EEG electrodes. The team discovered that the e-tattoos’ ability to detect brainwaves with little noise was comparable.
The conventional electrodes’ gel began to dry out after six hours. More than one-third of these electrodes were unable to detect any signal, but the majority of the other electrodes had less skin contact, which led to less precise signal detection. However, for a minimum of twenty-four hours, the e-tattoo electrodes demonstrated consistent connectivity.
In addition, researchers modified the ink’s composition and substituted the wires used in a typical EEG test with e-tattoo lines that extend from the electrodes to the base of the head.
The University of California, Los Angeles’s Ximin He, co-corresponding author, says, “This modification allowed the printed wires to conduct signals without picking up new signals along the way.”.
Between the tattoos, the team connected much shorter physical wires to a tiny gadget that records brainwaves. The team stated that in order to accomplish a completely wireless EEG procedure, they intend to incorporate wireless data transmitters into the e-tattoos in the future.
According to co-corresponding author José Millán of the University of Texas at Austin, “Our study has the potential to completely change the design of non-invasive brain-computer interface devices.”.
In order to operate an external device without requiring the user to move a muscle, brain-computer interface devices record brain activity related to a function, like speech or movement.
At the moment, these gadgets frequently require a big, difficult-to-use headset. According to Millán, e-tattoos have the potential to take the place of an external device and print the electronics straight onto a patient’s head, increasing accessibility to brain-computer interface technology.
