Flexible boron-doped diamond spiral electrode for application in brain–computer interface based on steady-state visual evoked potential

Abstract

We propose a flexible boron-doped diamond (BDD) spiral electrode for electroencephalography (EEG) recording and introduce the application of a flexible BDD-based EEG cap in brain–computer interfaces (BCI). The B-doping difference of diamond crystal planes in flexible polycrystalline BDD electrodes makes them act like a microelectrode. Hydrogen bonds between hydroxy fatty acid in the cuticle and BDD surface terminal and electrostatic adsorption between BDD-boron sites and the cuticle enhance the capacitive electric field. Combining a skin-conformal BDD electrode cap with the simplest feature extraction and classification coding can record highly stable EEG in steady-state visual evoked potential (SSVEP), with a high average SNR of 8.6 dB. The BCI system demonstrated competitive accuracy and information transfer rate in five channels in the occipital and parietal areas. Collectively, the BDD-based SSVEP-BCI system offers unique advantages for the real-time monitoring of brain signals, neurological rehabilitation, and disease diagnosis.