Metrological Characterization of Consumer-Grade Equipment for Wearable Brain–Computer Interfaces and Extended Reality

This article proposes the characterization of stimulation and detection equipment in the design of wearable brain–computer interfaces (BCIs) based on visually evoked potentials. In particular, methods for the characterization of the optical output of commercial smart glasses and for the calibration of a low-cost electroencephalograph (EEG) are presented and discussed. The reported results show that, by proper characterization and calibration, consumer-grade equipment is suitable for BCI applications. Moreover, unexpected harmonics of the visual stimuli have to be taken into account by suitable processing. Finally, the EEG shows an adequate linear behavior, but its gain error of around 10% should be corrected by calibration in some applications.