Koo Beomseo, Weiland James
Annu Int Conf IEEE Eng Med Biol Soc. 2018 Jul;2018:2949-2952. doi: 10.1109/EMBC.2018.8512973.
Impedance measurement using Electrochemical Impedance Spectroscopy is a widely utilized technique in neural electrodes. Research and clinical devices that incorporate stimulating and recording microelectrodes routinely characterize the material's integrity and its functionality through impedance measurement. Nominal impedance values ensure a stable neural electrode-tissue contact capable of passing through power efficient electric signals with desired signal-tonoise ratio or effective volume coverage. However, the complexity of the in vivo environment limits the usage of the three-electrode setup, which has been accepted as the ideal method in providing a stable impedance measurement. Impedance data measured from microelectrodes in threeelectrode and two-electrode setups show that the two setups have similar outcomes in terms of the impedance modulus over a 0.5 Hz-100 kHz frequency range. Usage of a platinum counter electrode lowered the overall variance in impedance readings compared to the stainless steel counter electrode. However, correlation coefficient values $(>0.97)$ between three-electrode and two-electrode setups show that impedance values seldom deviate due to changes in electrode setup. Based on the results of this study, the usage of the two-electrode setup in vivo allowed acceptable electrochemical impedance spectroscopy accuracy, and the utilization of a platinum counter electrode is recommended to reduce measurement variance.
使用电化学阻抗谱进行阻抗测量是神经电极中广泛应用的技术。包含刺激和记录微电极的研究和临床设备通常通过阻抗测量来表征材料的完整性及其功能。标称阻抗值可确保神经电极与组织的稳定接触，能够以所需的信噪比或有效体积覆盖率传递高效能电信号。然而，体内环境的复杂性限制了三电极设置的使用，而三电极设置已被公认为提供稳定阻抗测量的理想方法。在三电极和两电极设置中从微电极测量的阻抗数据表明，在0.5 Hz - 100 kHz频率范围内，两种设置在阻抗模量方面具有相似的结果。与不锈钢对电极相比，使用铂对电极降低了阻抗读数的总体方差。然而，三电极和两电极设置之间的相关系数值（>0.97）表明，阻抗值很少因电极设置的变化而偏离。基于本研究的结果，在体内使用两电极设置可获得可接受的电化学阻抗谱精度，建议使用铂对电极以减少测量方差。
