Harris Alexander R, Grayden David B, John Sam E
Department of Biomedical Engineering, University of Melbourne, Melbourne 3010, Australia.
Graeme Clark Institute, University of Melbourne, Melbourne 3010, Australia.
Micromachines (Basel). 2023 Mar 24;14(4):722. doi: 10.3390/mi14040722.
Electrodes are used in vivo for chemical sensing, electrophysiological recording, and stimulation of tissue. The electrode configuration used in vivo is often optimised for a specific anatomy and biological or clinical outcomes, not electrochemical performance. Electrode materials and geometries are constrained by biostability and biocompatibility issues and may be required to function clinically for decades. We performed benchtop electrochemistry, with changes in reference electrode, smaller counter-electrode sizes, and three- or two-electrode configurations. We detail the effects different electrode configurations have on typical electroanalytical techniques used on implanted electrodes. Changes in reference electrode required correction by application of an offset potential. In a two-electrode configuration with similar working and reference/counter-electrode sizes, the electrochemical response was dictated by the rate-limiting charge transfer step at either electrode. This could invalidate calibration curves, standard analytical methods, and equations, and prevent use of commercial simulation software. We provide methods for determining if an electrode configuration is affecting the in vivo electrochemical response. We recommend sufficient details be provided in experimental sections on electronics, electrode configuration, and their calibration to justify results and discussion. In conclusion, the experimental limitations of performing in vivo electrochemistry may dictate what types of measurements and analyses are possible, such as obtaining relative rather than absolute measurements.
电极在体内用于化学传感、电生理记录以及组织刺激。体内使用的电极配置通常针对特定的解剖结构以及生物学或临床结果进行优化，而非针对电化学性能。电极材料和几何形状受到生物稳定性和生物相容性问题的限制，并且可能需要在临床上发挥作用数十年。我们进行了台式电化学实验，改变了参比电极、减小了对电极尺寸，并采用了三电极或两电极配置。我们详细阐述了不同电极配置对植入电极上使用的典型电分析技术的影响。参比电极的变化需要通过施加偏移电位来校正。在工作电极与参比/对电极尺寸相似的两电极配置中，电化学响应由任一电极上的限速电荷转移步骤决定。这可能会使校准曲线、标准分析方法和方程无效，并妨碍使用商业模拟软件。我们提供了确定电极配置是否影响体内电化学响应的方法。我们建议在关于电子设备、电极配置及其校准的实验部分提供足够的细节，以证明结果和讨论的合理性。总之，进行体内电化学实验的局限性可能决定了哪些类型的测量和分析是可行的，例如获得相对而非绝对测量值。
