Electroencephalography (EEG) is widely used to study brain activity, but the electrodes that are typically used to record brainwaves on the scalp make it impractical to use EEG for extended periods of time. They are usually hard, require a gel to be applied, and are applied en masse using a tightly worn head cap. Now, researchers at Graz University of Technology in Austria have developed ultra-thin electrodes that can be manufactured using inject printers and worn unobtrusively on the head for long periods of time.
The electrodes resemble skin tattoos, because they are made using a conductive polymer coating on conventional tattoo paper. The Graz researchers were able to fine tune these EEG tattoos to have just the right thickness and composition to optimize the impedance and recorded signal quality when interfacing with the scalp. “Brain waves are in the low frequency range and EEG signals have a very low amplitude. They are much more difficult to capture in high quality than EMG or ECG signals,” said Laura Ferrari, one of the researchers behind the new electrodes.
Using the new electrodes, the researchers compared the signal fidelity with that from conventional commercial electrodes, finding near unanimity between the recordings. However, the price difference between conventional electrodes and these cheap printed ones is striking. The ease of wear and ability to use them over long periods of time is also impressive.
Additionally, the new electrodes are safe to use alongside magneto-encephalography (MEG), a major development since only wet, short lasting EEG electrodes have been compatible with MEG to date. This new capability should allow for long term brain monitoring under EEG and MEG at the same time, potentially helping to resolve a number of issues that are currently poorly understood by neuroscientists.
Here’s Francesco Greco, the lead researcher behind the new electrodes, showing off the new technology:
Open access study in journal npj Flexible Electronics: Conducting polymer tattoo electrodes in clinical electro- and magneto-encephalography
Flashback: Temporary Graphene Tattoo Measures Vitals
Via: TU Graz