In the USA they have learned to print electrodes for brain-computer interfaces directly on the head

Researchers at the University of Texas and the University of California at Los Angeles have developed an experimental method for 3D printing “tattoos” on the head from conductive polymers. These “tattoos” work like traditional electroencephalographic (EEG) electrodes, which are used for brain-computer interfaces (BCI) and provide control of robotic limbs, computers, and objects in virtual reality environments.

Image source: Cell Biomaterials

The brain constantly generates electrical signals that change depending on different thoughts and movements. Invasive (implantable) BCI interfaces allow precise reading of brain signals. However, this approach to the implementation of brain-computer interfaces creates the possibility of infection or implant rejection, and in general is not very safe. Printing electrodes on the scalp is much easier.

Electrodes placed individually on the scalp or using EEG caps can also read brain signals, although not as accurately as implants. Subsequent processing of the received signals using artificial intelligence algorithms makes it possible to improve the accuracy of reading brain signals, but without additional extensive study of this area, printed EEG electrodes will be comparable in accuracy to traditional encephalography.

Developed by researchers at the University of Texas and UCLA, the electrodes are made from a conductive polymer called PEDOT:PSS, which is applied to the head as a liquid using a microinkjet 3D printer. The scientists note that PEDOT:PSS remains elastic after curing, so it can also be used to create both stretchable electronics and stretchable displays.

The process of creating electrodes begins with scanning the patient’s head. After this, the required design of EEG electrodes is selected on the computer. It takes only ten minutes to print ten EEG electrodes, plus five minutes for subsequent calibration. This is significantly less time than it usually takes to install traditional EEG electrodes. Additionally, 3D printed electrodes eliminate the need to use a special wet compound to ensure better electrode-to-skin contact. Typically, this substance dries quickly, making the traditional encephalography process ineffective.

The researchers shared their experimental method for 3D printing “tattoos” on the head from conductive polymers in an article in the journal Cell Biomaterials.