Li Guangli, Liu Ying, Chen Yuwei, Li Mingzhe, Song Jian, Li Kanghua, Zhang Youmei, Hu Le, Qi Xiaoman, Wan Xuan, Liu Jun, He Quanguo, Zhou Haihan
Hunan Key Laboratory of Biomedical Nanomaterials and Devices, College of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, People's Republic of China.
Department of Neurology, Zhuzhou People's Hospital, Zhuzhou 412008, People's Republic of China.
J Neural Eng. 2023 Mar 17;20(2). doi: 10.1088/1741-2552/acc098.
Reliable and user-friendly electrodes can continuously and real-time capture the electroencephalography (EEG) signals, which is essential for real-life braincomputer interfaces (BCIs). This study develops a flexible, durable, and low-contact-impedance polyvinyl alcohol/polyacrylamide double-network hydrogel (PVA/PAM DNH)-based semi-dry electrode for robust EEG recording at hairy scalp.The PVA/PAM DNHs are developed using a cyclic freeze-thaw strategy and used as a saline reservoir for semi-dry electrodes. The PVA/PAM DNHs steadily deliver trace amounts of saline onto the scalp, enabling low and stable electrode-scalp impedance. The hydrogel also conforms well to the wet scalp, stabilizing the electrode-scalp interface. The feasibility of the real-life BCIs is validated by conducting four classic BCI paradigms on 16 participants.The results show that the PVA/PAM DNHs with 7.5 wt% PVA achieve a satisfactory trade-off between the saline load-unloading capacity and the compressive strength. The proposed semi-dry electrode exhibits a low contact impedance (18 ± 8.9 kΩ at 10 Hz), a small offset potential (0.46 mV), and negligible potential drift (1.5 ± 0.4V min). The temporal cross-correlation between the semi-dry and wet electrodes is 0.91, and the spectral coherence is higher than 0.90 at frequencies below 45 Hz. Furthermore, no significant differences are present in BCI classification accuracy between these two typical electrodes.Based on the durability, rapid setup, wear-comfort, and robust signals of the developed hydrogel, PVA/PAM DNH-based semi-dry electrodes are a promising alternative to wet electrodes in real-life BCIs.
可靠且用户友好的电极能够连续实时地捕捉脑电图（EEG）信号，这对于实际应用中的脑机接口（BCI）至关重要。本研究开发了一种基于柔性、耐用且低接触阻抗的聚乙烯醇/聚丙烯酰胺双网络水凝胶（PVA/PAM DNH）的半干电极，用于在多毛发头皮上进行稳健的EEG记录。PVA/PAM DNH通过循环冻融策略制备，并用作半干电极的盐水储存器。PVA/PAM DNH能稳定地向头皮输送微量盐水，从而实现低且稳定的电极 - 头皮阻抗。该水凝胶还能很好地贴合湿润的头皮，稳定电极 - 头皮界面。通过对16名参与者进行四种经典的BCI范式，验证了实际应用中BCI的可行性。结果表明，含7.5 wt% PVA的PVA/PAM DNH在盐水加载 - 卸载能力和抗压强度之间实现了令人满意的平衡。所提出的半干电极表现出低接触阻抗（10 Hz时为18 ± 8.9 kΩ）、小的偏移电位（0.46 mV）和可忽略不计的电位漂移（1.5 ± 0.4V/min）。半干电极与湿电极之间的时间互相关系数为0.91，在45 Hz以下频率的谱相干性高于0.90。此外，这两种典型电极在BCI分类准确率上没有显著差异。基于所开发水凝胶的耐用性、快速设置、佩戴舒适性和稳健信号，基于PVA/PAM DNH的半干电极在实际应用的BCI中是湿电极的一种有前景的替代方案。
