Bioengineering, Temple University, Philadelphia, PA 19122, USA.
Bioengineering, Temple University, Philadelphia, PA 19122, USA.
J Neurosci Methods. 2018 Sep 1;307:70-83. doi: 10.1016/j.jneumeth.2018.06.020. Epub 2018 Jun 28.
Metal electrodes are a mainstay of neuroscience. Characterization of the electrical impedance properties of these cuffs is important to ensure successful and repeatable fabrication, achieve a target impedance, revise novel designs, and quantify the success or failure of implantation and any potential subsequent damage or encapsulation by scar tissue.
Impedances are frequently characterized using lumped-parameter circuit models of the electrode-electrolyte interface. Open-source tools to gather and analyze these frequency sweep data are lacking. Here, we present such software, in the form of Matlab code, which includes a GUI. It automatically acquires frequency sweep data and subsequently fits a simplified Randles model to these data, over a user specified frequency range, providing the user with the model parameter estimates. Also, it can measure an unknown impedance of an element over a range of frequencies, as long as an external resistor can be added for the measurements.
The tool was tested on five bright platinum nerve cuffs in vitro. The average charge transfer resistance, solution resistance, CPE value, and impedance magnitude were estimated.
The measured values of the impedance of cuffs were in agreement with the literature (Wei and Grill, 2009). Variation between cuffs fabricated as consistently as possible amounted to 10% for impedance magnitude and 4° for impedance phase.
The results show that this low-cost tool can be used to characterize a cuff across different conditions including after implantation. The latter makes it useful for a longer-term study of electrode viability.
金属电极是神经科学的主要研究对象。对这些袖口的电阻抗特性进行表征对于确保成功且可重复的制造、达到目标电阻抗、改进新型设计以及量化植入的成功或失败以及任何潜在的后续损伤或瘢痕组织的封装非常重要。
电极-电解质界面的集总参数电路模型常用于阻抗特性的表征。缺乏用于收集和分析这些频率扫描数据的开源工具。在这里，我们以 Matlab 代码的形式提供了这样的软件，其中包括一个图形用户界面。它可以自动获取频率扫描数据，并随后在用户指定的频率范围内对这些数据进行简化的 Randles 模型拟合，为用户提供模型参数估计。此外，只要可以添加外部电阻器进行测量，它就可以在一定频率范围内测量未知元件的阻抗。
该工具在五个明亮的铂神经袖口上进行了测试。估计了电荷转移电阻、溶液电阻、CPE 值和阻抗幅度。
袖口阻抗的测量值与文献（Wei 和 Grill，2009）一致。尽可能一致地制造的袖口之间的差异在阻抗幅度上为 10%，在阻抗相位上为 4°。
结果表明，这种低成本工具可用于表征不同条件下的袖口，包括植入后。这使得它在电极生存能力的长期研究中非常有用。
