Advancements in dry and semi-dry EEG electrodes: Design, interface characteristics, and performance evaluation

Electroencephalography (EEG) technology, as a crucial tool for monitoring brain function, has undergone significant technological advancements and improvements in recent years. Among these advancements, electrode technology, as a core component of EEG systems, continues to drive its development. This paper systematically reviews and categorizes various types of EEG electrodes from the perspectives of electrode structure and materials, with a focus on principles, design characteristics, and pros and cons of semi-dry and dry electrodes. In addition, it delves into the interface characteristics of EEG electrodes, analyzing the impact of electrode interface dimensions, materials, and structures on the equivalent circuit models of electrode–skin interfaces, electrode–skin contact impedance, and motion artifact suppression capabilities. This paper also introduces methods for evaluating electrode performance, emphasizing approaches to verify the signal acquisition capabilities and stability of novel electrodes through specific experimental paradigms and comparative analyses. Through comprehensive review and in-depth analysis, this paper aims to provide profound theoretical references and practical guidance for further research and real-world applications of EEG electrode technology.