Graduate School of Biomedical Engineering, University of New South Wales, Sydney 2052, Australia.
J Neural Eng. 2013 Feb;10(1):016009. doi: 10.1088/1741-2560/10/1/016009. Epub 2013 Jan 3.
Recent interest in the use of conducting polymers (CPs) for neural stimulation electrodes has been growing; however, concerns remain regarding the stability of coatings under stimulation conditions. These studies examine the factors of the CP and implant environment that affect coating stability. The CP poly(ethylene dioxythiophene) (PEDOT) is examined in comparison to platinum (Pt), to demonstrate the potential performance of these coatings in neuroprosthetic applications.
PEDOT is coated on Pt microelectrode arrays and assessed in vitro for charge injection limit and long-term stability under stimulation in biologically relevant electrolytes. Physical and electrical stability of coatings following ethylene oxide (ETO) sterilization is established and efficacy of PEDOT as a visual prosthesis bioelectrode is assessed in the feline model.
It was demonstrated that PEDOT reduced the potential excursion at a Pt electrode interface by 72% in biologically relevant solutions. The charge injection limit of PEDOT for material stability was found to be on average 30× larger than Pt when tested in physiological saline and 20× larger than Pt when tested in protein supplemented media. Additionally stability of the coating was confirmed electrically and morphologically following ETO processing. It was demonstrated that PEDOT-coated electrodes had lower potential excursions in vivo and electrically evoked potentials (EEPs) could be detected within the visual cortex.
These studies demonstrate that PEDOT can be produced as a stable electrode coating which can be sterilized and perform effectively and safely in neuroprosthetic applications. Furthermore these findings address the necessity for characterizing in vitro properties of electrodes in biologically relevant milieu which mimic the in vivo environment more closely.
最近人们对使用导电聚合物 (CPs) 作为神经刺激电极越来越感兴趣；然而，人们仍然对涂层在刺激条件下的稳定性存在担忧。这些研究探讨了影响涂层稳定性的 CP 和植入物环境因素。与铂 (Pt) 相比，研究了 CP 聚 (3,4-亚乙基二氧噻吩) (PEDOT)，以展示这些涂层在神经假体应用中的潜在性能。
将 PEDOT 涂覆在 Pt 微电极阵列上，并在体外评估其在生物相关电解质中刺激下的电荷注入极限和长期稳定性。建立了涂层在环氧乙烷 (ETO) 灭菌后的物理和电气稳定性，并在猫模型中评估了 PEDOT 作为视觉假体生物电极的功效。
结果表明，PEDOT 在生物相关溶液中将 Pt 电极界面的电位偏移降低了 72%。在生理盐水和蛋白质补充培养基中分别测试时，PEDOT 的电荷注入极限比 Pt 分别大 30 倍和 20 倍，证明了 PEDOT 用于材料稳定性的极限。此外，涂层在 ETO 处理后在电气和形态上均保持稳定。结果表明，PEDOT 涂层电极在体内的电位偏移较小，并且可以在视觉皮层中检测到电诱发电位 (EEPs)。
这些研究表明，可以生产稳定的 PEDOT 电极涂层，该涂层可以进行灭菌，并在神经假体应用中有效且安全地运行。此外，这些发现解决了在更接近体内环境的生物相关环境中对电极的体外特性进行表征的必要性。
