Aregueta-Robles Ulises A, Woolley Andrew J, Poole-Warren Laura A, Lovell Nigel H, Green Rylie A
Graduate School of Biomedical Engineering, University of New South Wales Sydney, NSW, Australia.
Graduate School of Biomedical Engineering, University of New South Wales Sydney, NSW, Australia ; School of Medicine, University of Western Sydney Sydney, NSW, Australia.
Front Neuroeng. 2014 May 27;7:15. doi: 10.3389/fneng.2014.00015. eCollection 2014.
Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however, several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes.
传统的神经元接口使用金属电极，近年来，在以高分辨率或更确切地说是以高密度微电极提供安全刺激并具有更高空间选择性的能力方面，金属电极已达到了一个平台期。为了实现更高的分辨率，显然需要减小电极尺寸，以便从植入设备获得更多数量的电极。包括低电荷注入限制、机械不匹配和异物反应在内的电极接口限制，可以通过使用有机电极涂层来解决，有机电极涂层通常提供更柔软、更粗糙的表面，以实现更好的电荷转移，并降低与神经组织的机械不匹配。与传统的铂电极相比，用导电聚合物或碳纳米管涂覆电极可大幅增加电荷转移面积。这些有机导体可对组织进行安全的电刺激，同时避免不良化学反应和细胞损伤。然而，导电聚合物的机械性能并不理想，因为它们相当脆。水凝胶聚合物为电极提供了一种通用的涂层选择，因为它们可以进行化学修饰以提供柔软且导电的支架。然而，这些导电水凝胶在体内的慢性炎症反应仍然未知。最近的一种方法提出通过在水凝胶涂层中使用封装的神经元对电极界面进行组织工程化。这种方法可能提供一种在细胞水平激活组织的方法，然而，必须解决几个技术挑战才能证明这一创新想法的可行性。这篇综述重点关注了为改善神经接口电极而研究的各种有机涂层。
