Fu Xuefeng, Li Gen, Niu Yutao, Xu Jingcao, Wang Puxin, Zhou Zhaoxiao, Ye Ziming, Liu Xiaojun, Xu Zheng, Yang Ziqian, Zhang Yongyi, Lei Ting, Zhang Baogui, Li Qingwen, Cao Anyuan, Jiang Tianzai, Duan Xiaojie
Department of Biomedical Engineering, College of Future Technology, Peking University, Beijing, China.
School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei, China.
Front Neurosci. 2021 Dec 22;15:771980. doi: 10.3389/fnins.2021.771980. eCollection 2021.
Implantable brain electrophysiology electrodes are valuable tools in both fundamental and applied neuroscience due to their ability to record neural activity with high spatiotemporal resolution from shallow and deep brain regions. Their use has been hindered, however, by the challenges in achieving chronically stable operations. Furthermore, implantable depth neural electrodes can only carry out limited data sampling within predefined anatomical regions, making it challenging to perform large-area brain mapping. Minimizing inflammatory responses and associated gliosis formation, and improving the durability and stability of the electrode insulation layers are critical to achieve long-term stable neural recording and stimulation. Combining electrophysiological measurements with simultaneous whole-brain imaging techniques, such as magnetic resonance imaging (MRI), provides a useful solution to alleviate the challenge in scalability of implantable depth electrodes. In recent years, various carbon-based materials have been used to fabricate flexible neural depth electrodes with reduced inflammatory responses and MRI-compatible electrodes, which allows structural and functional MRI mapping of the whole brain without obstructing any brain regions around the electrodes. Here, we conducted a systematic comparative evaluation on the electrochemical properties, mechanical properties, and MRI compatibility of different kinds of carbon-based fiber materials, including carbon nanotube fibers, graphene fibers, and carbon fibers. We also developed a strategy to improve the stability of the electrode insulation without sacrificing the flexibility of the implantable depth electrodes by sandwiching an inorganic barrier layer inside the polymer insulation film. These studies provide us with important insights into choosing the most suitable materials for next-generation implantable depth electrodes with unique capabilities for applications in both fundamental and translational neuroscience research.
可植入式脑电生理电极是基础神经科学和应用神经科学中的宝贵工具，因为它们能够以高时空分辨率记录来自浅部和深部脑区的神经活动。然而，实现长期稳定运行的挑战阻碍了它们的使用。此外，可植入式深度神经电极只能在预定义的解剖区域内进行有限的数据采样，这使得进行大面积脑图谱绘制具有挑战性。将炎症反应和相关的胶质增生形成降至最低，并提高电极绝缘层的耐久性和稳定性，对于实现长期稳定的神经记录和刺激至关重要。将电生理测量与同步全脑成像技术（如磁共振成像（MRI））相结合，为缓解可植入式深度电极的可扩展性挑战提供了一个有用的解决方案。近年来，各种碳基材料已被用于制造具有降低炎症反应的柔性神经深度电极和与MRI兼容的电极，这使得能够对全脑进行结构和功能MRI图谱绘制，而不会阻碍电极周围的任何脑区。在此，我们对不同种类的碳基纤维材料（包括碳纳米管纤维、石墨烯纤维和碳纤维）的电化学性能、机械性能和MRI兼容性进行了系统的比较评估。我们还开发了一种策略，通过在聚合物绝缘膜内部夹入无机阻挡层来提高电极绝缘的稳定性，同时不牺牲可植入式深度电极的柔韧性。这些研究为我们在选择最适合的材料用于下一代可植入式深度电极方面提供了重要见解，这些电极具有独特的能力，可应用于基础神经科学研究和转化神经科学研究。
