Laboratory for Sensors, IMTEK-Department of Microsystems Engineering, University of Freiburg, Freiburg, Germany.
BrainLinks-BrainTools Center, University of Freiburg, Freiburg, Germany.
J Neural Eng. 2021 Oct 5;18(5). doi: 10.1088/1741-2552/ac28d5.
. Neural interfaces often rely on charge transfer processes between electrodes and the tissue or electrolyte. Electrochemical processes are at the core of electrode function and, therefore, the key to neural interface stability, electrode performance characterization, and utilization of electrodes as chemical sensors. Electrochemical techniques offer a variety of options to investigate the charge transfer and electrocatalytic properties of electrodes.. In this tutorial, we present various experiments to illustrate the power of electrochemical methods, serve as a reference and guideline, and stimulate deeper understanding of the subject.As a basis for the following experiments, we discuss the platinum cyclic voltammogram and focus on understanding surface processes and roughness determination. We highlight the importance of appropriate instrumentation using potentiostats and how strongly it can influence results. We then discuss a number of potential-controlled and current-controlled methods for electrode characterization, including chronocoulometry, chronoamperometry, (active) potentiometry, and chronopotentiometry. They illustrate charge transfer caused by both electrode surface processes and the presence of redox-active species, such as dissolved oxygen and hydrogen, or hydrogen peroxide. We also discuss the electrode potential with respect to a reference electrode under various conditions and how it affects its electrochemical properties like surface state, catalytic properties and capability to transfer charge.Electrochemical methods are still underutilized in neural engineering, and valuable information is therefore often not accessed. Many studies on electrode characterization would benefit from a more consistent and target-oriented electrochemical methodology and instrumentation. That ranges from the investigation of new materials and processes, over electrode performance assessment to the development of more long-term stable and biocompatible neural interfaces. Ultimately, standardization, consistency and comparability will play a key role in the translation of microtechnology into biomedical and clinical applications.
. 神经接口通常依赖于电极与组织或电解质之间的电荷转移过程。电化学过程是电极功能的核心，因此是神经接口稳定性、电极性能表征以及将电极用作化学传感器的关键。电化学技术为研究电极的电荷转移和电催化特性提供了多种选择。. 在本教程中，我们展示了各种实验，以说明电化学方法的强大功能，作为参考和指南，并激发对该主题的更深入理解。. 作为以下实验的基础，我们讨论了铂的循环伏安图，并重点讨论了理解表面过程和粗糙度测定。我们强调了使用恒电位仪的适当仪器的重要性，以及它对结果的强烈影响。然后，我们讨论了几种用于电极表征的电位控制和电流控制方法，包括计时库仑法、计时电流法、（活性）电位法和计时电位法。它们说明了由电极表面过程和溶解氧、氢或过氧化氢等氧化还原活性物质引起的电荷转移。我们还讨论了在各种条件下相对于参比电极的电极电位以及它如何影响其电化学性质，如表面状态、催化性质和电荷转移能力。. 电化学方法在神经工程中仍未得到充分利用，因此经常无法获取有价值的信息。许多关于电极表征的研究将受益于更一致和有针对性的电化学方法和仪器。这范围从新材料和工艺的研究，到电极性能评估，再到更长期稳定和生物相容的神经接口的开发。最终，标准化、一致性和可比性将在微技术向生物医学和临床应用的转化中发挥关键作用。
