Tracking Carbon Microelectrode Impedance during Fast-Scan Cyclic Voltammetry

Fast-scan cyclic voltammetry (FSCV) is a powerful technique for monitoring rapid neurochemical fluctuations in living animals.  When paired with permanently implanted carbon-fiber microelectrodes, changes in neurochemical dynamics can be monitored over months and related to changes in behavior. However, the performance and electrical properties of handmade microelectrodes are variable and impacted by the biological response to implantation and the physical and chemical diversity of recording environments. These factors collectively impact calibration factors and the shape of the cyclic voltammograms (CVs) that are used for analyte quantification and identification. We previously reported that model RC circuits of variable impedance could be utilized to mimic the observed shifts in FSCV performance that develop in vivo. In this work, an electrochemical impedance spectroscopy (EIS) measurement was incorporated within each voltammetric sweep to provide information on rapid changes in impedance, reactance, and capacitance that impact the electrochemical system during the FSCV experiment. The dataset, which was collected using standard FSCV equipment, quantifies large shifts in these parameters upon implantation in tissue, and correlates these shifts with voltammetric data. Shifts in impedance were largely mitigated by electrochemical conditioning. This paired FSCV:EIS paradigm can be used to inform users regarding changes in electrochemical performance that occur at any point during an in vivo experiment, representing a significant step towards in situ calibration strategies and improved accuracy in data analysis.

快速扫描循环伏安法 (Fast-scan cyclic voltammetry, FSCV) 是一种用于监测活体动物体内快速神经化学波动的高效技术。当与永久植入式碳纤维微电极 (carbon-fiber microelectrodes) 配合使用时，可在数月内追踪神经化学动力学的变化，并将其与动物行为改变相关联。然而，手工制备的微电极的性能与电学特性存在显著差异，且会受到植入后的生物反应以及记录环境的物理与化学多样性的影响。上述因素会共同影响校准系数以及用于分析物定量与识别的循环伏安图 (cyclic voltammograms, CVs) 的形态。本团队此前曾报道，可利用可变阻抗的RC电路模型，模拟体内环境下FSCV性能出现的观测偏移。本研究中，我们在每一次伏安扫描中都纳入了电化学阻抗谱 (electrochemical impedance spectroscopy, EIS) 测量，以获取FSCV实验过程中影响电化学系统的阻抗、电抗与电容的快速变化信息。本数据集采用标准FSCV设备采集，量化了电极植入组织后上述参数的显著偏移，并将这些偏移与伏安数据相关联。通过电化学活化处理，阻抗偏移可得到大幅缓解。这种FSCV与EIS联用的范式，可用于向使用者告知体内实验过程中任意时刻电化学性能的变化，是向原位校准策略及提升数据分析准确性迈出的重要一步。