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Stable and low-resistance polydopamine methacrylamide-polyacrylamide hydrogel for brain-computer interface

高稳定、 低电阻聚多巴胺甲基丙烯酰胺-聚丙烯酰胺水凝胶及其在脑机接口中的应用

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Abstract

Signal drift and performance instability of brain-computer interface devices induced by the interface failure between rigid metal electrodes and soft human skin hinder the precise data acquisition of electroencephalogram (EEG). Thus, it is desirable to achieve a robust interface for brain-computer interface devices. Here, a kind of polydopamine methacrylamide-polyacrylamide (PDMA-PAAM) hydrogel is developed. To improve the adhesion, dopamine is introduced into the polyacrylamide hydrogel, through the amino and catechol groups of dopamine in an organic-inorganic interface to build a covalent and non-covalent interaction. A strong attachment and an effective modulus transition system can be formed between the metal electrodes and human skin, so that the peeling force between the PDMA-PAAM hydrogel and the porcine skin can reach 22 N m−1. In addition, the stable conductivity and long-term operating life of the PDMA-PAAM hydrogel for more than 60 days at room temperature are achieved by adding sodium chloride (NaCl) and glycerol, respectively. The PDMA-PAAM hydrogel membrane fabricated in this work is integrated onto a flexible Au electrode applied in a brain-computer interface. In comparison, the collected EEG signal intensity and waveform are consistent with that of the commercial counterparts. And obviously, the flexible electrode with PDMA-PAAM hydrogel membrane is demonstrated to enable a more stable and user-friendly interface.

摘要

硬质金属电极与柔软人体皮肤之间的界面失效会导致脑机接口器件的信号漂移和性能不稳定, 影响脑电信号的精确采集. 本研究设计并制备了一种聚多巴胺甲基丙烯酰胺-聚丙烯酰胺(PDMA-PAAM)水凝胶. 将多巴胺引入到聚丙烯酰胺水凝胶中, 通过多巴胺的氨基与邻苯二酚基团在有机-无机界面上建立共价和非共价相互作用提高了界面粘结力. 金属电极与人体皮肤之间形成了强附着和有效模量过渡体系, PDMA-PAAM水凝胶与猪皮之间的剥离力达到22 N m−1. 此外, 通过添加氯化钠和甘油, PDMA-PAAM水凝胶具有稳定的电导率和室温下60天以上的长期使用寿命. 将本研究制备的PDMA-PAAM水凝胶集成在柔性金电极上用于脑机接口, 采集到的脑电信号强度和波形与同类商用产品基本一致, 且PDMA-PAAM水凝胶柔性电极具有更稳定的界面.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (U20A6001, 11921002, and 11902292), Zhejiang Province Key Research and Development Project (2021C01183, 2020C05004, and 2021C05007-4), and the Natural Science Foundation of Zhejiang Province of China (LQ19E030003).

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Authors and Affiliations

  1. Institute of Flexible Electronics Technology of THU, Zhejiang, Jiaxing Key Laboratory of Flexible Electronics based Intelligent Sensing and Advanced Manufacturing Technology, Jiaxing, 314000, China

    Lanlan Liu  (刘兰兰), Ruitao Tang  (唐瑞涛), Jun Ai  (艾骏) & Ying Chen  (陈颖)

  2. AML, Department of Engineering Mechanics, Centre for Flexible Electronics Technology, Tsinghua University, Beijing, 100084, China

    Yinji Ma  (马寅佶) & Xue Feng  (冯雪)

  3. Qiantang Science and Technology Innovation Center, Hangzhou, 310016, China

    Ying Chen  (陈颖)

  4. College of Aerospace Engineering, Chongqing University, Chongqing, 400044, China

    Yafeng Liu  (刘亚风)

Authors
  1. Lanlan Liu  (刘兰兰)
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Contributions

Author contributions Liu L and Liu Y designed the samples, performed the experiments and analyzed the data; Liu L wrote the paper with support from Tang R, Ai J and Ma Y; Chen Y and Feng X helped to analyze the data and conceived the framework of this paper. All authors contributed to the general discussion.

Corresponding authors

Correspondence to Ying Chen  (陈颖) or Xue Feng  (冯雪).

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Conflict of interest The authors declare that they have no conflict of interest.

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Supplementary information Supporting data are available in the online version of the paper.

Lanlan Liu received her PhD degree in chemistry from Beijing University of Chemical Technology in 2014, and then worked as a postdoc at the Institute of Chemistry, Chinese Academy of Sciences during 2014 to 2017. Currently, she is an associate researcher at the Institute of Flexible Electronics Technology of Tsinghua University (THU), Zhejiang. Her research focuses on flexible conductive materials, interfaces and devices, and their applications in the biomedical field.

Ying Chen received her PhD degree in solid mechanics from THU, Beijing in 2017. Currently, she is an associate researcher at the Institute of Flexible Electronics Technology of THU, Zhejiang and doing her postdoctoral research at Zhejiang University. She is working as the deputy director of Soft Matter Mechanics Committee of Zhejiang Society of Theoretical and Applied Mechanics. Her research interests include the mechanical design, MEMS fabrication and performance reliability analysis of flexible electronic devices.

Xue Feng received his PhD degree in mechanics from THU in 2003 and then worked as a postdoc at the University of Illinois at Urbana-Champaign during 2004 to 2007. From 2005 to 2006, he also worked as a postdoc at California Institute of Technology (Caltech). He joined THU in 2007. He is now a tenure professor of the School of Aerospace Engineering, THU, and he also serves as the director of the Ministry of Education Key Laboratory of Applied Mechanics of THU. His research focuses on the fundamental and applied science in flexible electronic technology, including the mechanics design and inorganic materials enabled integrated flexible devices.

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Liu, L., Liu, Y., Tang, R. et al. Stable and low-resistance polydopamine methacrylamide-polyacrylamide hydrogel for brain-computer interface. Sci. China Mater. 65, 2298–2308 (2022). https://doi.org/10.1007/s40843-022-2145-3

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