Did a quick search for "hair" since in my experience the most obnoxious part of using a traditional EEG cap was having to rinse the gel out of my hair in the sink afterwards (I was in a research study and had to do this multiple times a month, right before heading to class. Always left me looking disheveled). It looks like this approach works better for slightly hairy skin (the person in most of these figures has a buzz cut) than other e-tattoo methods but they do note:
> More work is needed to scan and print on heads with long and thick hairs. Highlighting the persistent issue of racial bias in neuroscience research is crucial, as traditional EEG electrodes are often unreliable on individuals of African descent, resulting in suboptimal patient experiences and outcomes in clinical settings.69,70 Curly hairs tend to push against the EEG cap, reducing contact between the electrodes and the scalp, leading to a poor contact impedance.71 Developing on-scalp digital printing for different hair types should prioritize bridging this important gap.
> Traditional electroencephalography (EEG) systems involve time-consuming manual electrode placement, conductive liquid gels, and cumbersome cables, which are prone to signal degradation and discomfort during prolonged use. Our approach overcomes these limitations by combining material innovations with non-contact, on-body digital printing techniques to fabricate e-tattoos that are self-drying, ultrathin, and compatible with hairy scalps. These skin-conformal EEG e-tattoo sensors enable comfortable, long-term, high-quality brain activity monitoring without the discomfort associated with traditional EEG systems. Using individual 3D head scans, custom sensor layout design, and a 5-axis microjet printing robot, we have created EEG e-tattoos with precise, tailored placement over the entire scalp. The inks for electrodes and interconnects have slightly different compositions to achieve low skin contact impedance and high bulk conductivity, respectively
does the thicness of the material effect conductivity?
could you have stensel or this?
Is the placement of the electrodes need sub milimiter accureacy?
> More work is needed to scan and print on heads with long and thick hairs. Highlighting the persistent issue of racial bias in neuroscience research is crucial, as traditional EEG electrodes are often unreliable on individuals of African descent, resulting in suboptimal patient experiences and outcomes in clinical settings.69,70 Curly hairs tend to push against the EEG cap, reducing contact between the electrodes and the scalp, leading to a poor contact impedance.71 Developing on-scalp digital printing for different hair types should prioritize bridging this important gap.