Tissue-compliant neural implants from microfabricated carbon nanotube multilayer composite.
Tissue-compliant neural implants from microfabricated carbon nanotube multilayer composite.
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DOI：
10.1021/nn402074y
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发表时间：
2013-08
期刊：
影响因子：
17.1
通讯作者：
Huanan Zhang;Paras R. Patel;Zhixing Xie;S. Swanson;Xueding Wang;N. Kotov
中科院分区：
文献类型：
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作者：
Huanan Zhang;Paras R. Patel;Zhixing Xie;S. Swanson;Xueding Wang;N. Kotov
目前的神经假体装置(NPD)由于复杂的机械和生物反应而导致慢性炎症，部分原因是与神经组织的机械特性惊人的差异有关。植入物相对较大的尺寸和对血脑屏障的创伤也会导致炎症反应。这些问题的缓解和长期脑界面的实现需要由与脑组织相适应的柔性材料制成的新一代NPD。然而，这类材料将需要表现出难以结合的机械和电学性能，而这是经典神经技术工具箱中无法获得的。此外，这些新材料将同时需要不同的方法(A)设备微制造和(B)脑内外科植入，因为目前使用的工艺利用了设备的高刚性。碳纳米管(CNT)具有优异的力学和电学性能，可作为此类材料的基础材料，但基于CNT的组织顺应性器件尚未实现。在这项研究中，我们根据脑组织的临界破裂强度来形式化对组织顺应性植入物的力学要求，并证明基于微型碳纳米管的设备可以满足这些要求。我们使用类似MEMS的技术制造了它们，并将其微型化，使至少两个维度的电极可以与脑组织细胞相媲美。利用专门为软组织顺应性植入物设计的外科手术程序，将基于纳米复合材料的柔性神经电极植入大鼠的运动皮质。通过磁共振和光声成像，成功地显示了术后种植体在运动皮质的定位。通过在麻醉大鼠活体大脑中成功记录低频神经记录，证明了体内的功能。需要对这些电极周围的炎症过程进行研究，才能确定它们作为长期神经电极的前景。
Current neural prosthetic devices (NPDs) induce chronic inflammation due to complex mechanical and biological reactions related, in part, to staggering discrepancies of mechanical properties with neural tissue. Relatively large size of the implants and traumas to blood-brain barrier contribute to inflammation reactions, as well. Mitigation of these problems and the realization of long-term brain interface require a new generation of NPDs fabricated from flexible materials compliant with the brain tissue. However, such materials will need to display hard-to-combine mechanical and electrical properties which are not available in the toolbox of classical neurotechnology. Moreover, these new materials will concomitantly demand different methods of (a) device micromanufacturing and (b) surgical implantation in brains because currently used processes take advantage of high stiffness of the devices. Carbon nanotubes (CNTs) serve as a promising foundation for such materials because of their record mechanical and electrical properties, but CNT-based tissue-compliant devices have not been realized yet. In this study, we formalize the mechanical requirements to tissue-compliant implants based on critical rupture strength of brain tissue and demonstrate that miniature CNT-based devices can satisfy these requirements. We fabricated them using MEMS-like technology and miniaturized them so that at least two dimensions of the electrodes would be comparable to brain tissue cells. The nanocomposite-based flexible neural electrodes were implanted into the rat motor cortex using a surgical procedure specifically designed for soft tissue-compliant implants. The post-surgery implant localization in the motor cortex was successfully visualized with magnetic resonance and photoacoustic imaging. In vivo functionality was demonstrated by successful registration of the low-frequency neural recording in the live brain of anesthetized rats. Investigation of inflammation processes around these electrodes will be required to establish their prospects as long-term neural electrodes.