Rezaei Babak, Saghir Saloua, Pan Jesper Yue, Davidsen Rasmus Schmidt, Keller Stephan Sylvest
National Centre for Nano Fabrication and Characterization, DTU Nanolab, Technical University of Denmark, 2800 Konges Lyngby, Denmark.
Micromachines (Basel). 2022 Feb 26;13(3):371. doi: 10.3390/mi13030371.
In this article, a novel approach for selective passivation of three-dimensional pyrolytic carbon microelectrodes via a facile electrochemical polymerization of a non-conductive polymer (polydopamine, PDA) onto the surface of carbon electrodes, followed by a selective laser ablation is elaborated. The 3D carbon electrodes consisting of 284 micropillars on a circular 2D carbon base layer were fabricated by pyrolysis of lithographically patterned negative photoresist SU-8. As a second step, dopamine was electropolymerized onto the electrode by cyclic voltammetry (CV) to provide an insulating layer at its surface. The CV parameters, such as the scan rate and the number of cycles, were investigated and optimized to achieve a reliable and uniform non-conductive coating on the surface of the 3D pyrolytic carbon electrode. Finally, the polydopamine was selectively removed only from the tips of the pillars, by using localized laser ablation. The selectively passivated electrodes were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy methods. Due to the surface being composed of highly biocompatible materials, such as pyrolytic carbon and polydopamine, these 3D electrodes are particularly suited for biological application, such as electrochemical monitoring of cells or retinal implants, where highly localized electrical stimulation of nerve cells is beneficial.
在本文中，阐述了一种新颖的方法，通过在碳电极表面将非导电聚合物（聚多巴胺，PDA）进行简便的电化学聚合，随后进行选择性激光烧蚀，对三维热解碳微电极进行选择性钝化。由光刻图案化的负性光刻胶SU-8热解制备的三维碳电极，在圆形二维碳基底层上由284个微柱组成。第二步，通过循环伏安法（CV）将多巴胺电聚合到电极上，以在其表面提供绝缘层。对CV参数，如扫描速率和循环次数进行了研究和优化，以在三维热解碳电极表面获得可靠且均匀的非导电涂层。最后，通过使用局部激光烧蚀，仅从柱体尖端选择性地去除聚多巴胺。通过扫描电子显微镜、循环伏安法和电化学阻抗谱方法对选择性钝化电极进行了表征。由于表面由高度生物相容性材料，如热解碳和聚多巴胺组成，这些三维电极特别适合生物应用，如细胞的电化学监测或视网膜植入，其中对神经细胞进行高度局部化的电刺激是有益的。
