EEG signal acquisition from the forehead and ears through textile-based 3D-printed electrodes to be integrated into a sensorized face-mask for astronauts' sleep monitoring

Continuous research into discrete methods and wearable devices for EEG acquisition has led to advanced solutions for sleep monitoring. This paper explores and tests two strategies to collect single-channel EEG for continuous sleep assessment: forehead and in-ear acquisition methods. First, a literature review was conducted on EEG acquisition methods from forehead, ear-, and in-ear setups, highlighting the benefits of the discussed solutions. Then, two single-channel EEG acquisition strategies were tested and compared by developing dedicated experimental setups: the first for the forehead acquisition, which measures the bipolar Fp1-Fp2 derivation, and the latter for the in-ear acquisition. Two earbuds, manufactured by 3D printing with flexible TPU filament, were realized, including two rectangular electrodes made of flexible conductive fabric (metallic nylon). Experimental results show that the in-ear EEG setup provides signals with greater amplitude and fewer artifacts than traditional methods while ensuring user comfort. This approach could improve the effectiveness and practicality of sleep EEG monitoring, supporting broader adoption in clinical and research applications.