Skin-mimetic adaptive gradient electrode for ambulatory noninvasive brain-computer interfaces

Noninvasive brain–computer interfaces (BCIs) need stable, comfortable electrodes for long-term wear. Current rigid or uniformly soft electrodes suffer from scalp mismatch, causing motion artifacts and short operation times. Inspired by human skin’s gradient structure, we created a skin-mimetic adaptive gradient electrode (AGE).

Based on the Marangoni effect, we induced heterogeneous crosslinking in the hydrogel within a gradient temperature field. This yields an electrode with a gradual stiffness change—soft at the scalp interface and firm at the circuit connection—along with a gradient pore structure for sustained electrolyte release. This design enabled stable, high-quality EEG recording for over 8 h during free movement and over 14 h at rest, maintaining >94% typing accuracy.

This work demonstrated the potential of gradient-designed hydrogels toward noninvasive BCIs in freely moving practicality. The Center for Instrumental Analysis of Guangxi University is acknowledged for providing partial experimental facilities. This work was financially supported by the National Natural Science Foundations of China (No. 32127801, 62104051, 32201095), Scientific Research Project of Wuming Hospital of Guangxi Medical University (No.

YNXM2025007), and Sichuan University Interdisciplinary Innovation Fund. These authors contributed equally: Jingjing Jiang, Huihe Chen. School of Physical Science and Technology, Guangxi University, Nanning, China Jingjing Jiang, Zhibao Huang, Zujing Feng, Xilin Li, Jieyu Huang, Jiawei Xie, Yongchun Liang, Yichen Liang, Zifang Tang, Zhenlong Zhao, Wenbo Wei, Jinbo Wang, Sheng Cao, Hongbang Liu & Sen Lin Department of Emergency and Critical Care Medicine, Wuming Hospital of Guangxi Medical University, Nanning, China Huihe Chen, Zujing Feng & Jianfeng Zhang State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, China Leibniz Institute for Neurobiology, Magdeburg, Germany Advanced Institute for Brain and Intelligence, Guangxi University, Nanning, China Xilin Li, Jieyu Huang, Wenbo Wei & Sen Lin Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, College of Animal Science and Technology, Guangxi University, Nanning, China School of Computer, Electronics and Information, Guangxi University, Nanning, China School of Aeronautics and Astronautics, Sichuan University, Chengdu, China Chongqing Institute for Brain and Intelligence, Guangyang Bay Laboratory, Chongqing, China Correspondence to Jianfeng Zhang, Hui Wu or Sen Lin.

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