Abstract: A novel dry electroencephalography (EEG) electrode was fabricated for the vigilance analysis based on EEG signal acquisition, which is conventionally acquired by wet electrodes. Flexible substrate MEMS fabrication technique was applied to fabricate the flexible dry micro-needle electrode array, which is chemical stable and bio-compatible. Featuring its cantilever structured micro-needles, the electrode was fabricated by wet etching of Cu sacrificial layer process. The electrodes were then released from substrate by PDMS lift-off process and packaged by polyimide, and finally fabricated a threedimensional electrode array by multi-layer assembly. Ni was electroplated to fabricate the micro-needles, the wire and the pads of the dry electrode to obtain mechanical strength while Au was electroplated on the surface of micro-needles for bio-compatibility. The performance of the dry electrode was tested by the amplifier of EEG acquisition, Neuroscan. The impedance of dry electrode was approximately 10 kΩ, and the similarity between the performances of dry and wet electrodes was proved by comparison of their time domain and frequency domain signals. With the advantage of high yield, small size, simple assembly, fine shielding, good reliability and mechanical strength, the dry electrode is capable of convenient and painless EEG signal acquisition.

Key words: dry electrode array, flexible substrate, microeletro mechanical system (MEMS) technique, multilayer assembly, electroencephalography (EEG)