Saoji Aniket A, Graham Madison K, DeJong Melissa D, Martin Joscelyn R K, Pesch Joerg, Vanpoucke Filiep J
Department of Otolaryngology-Head and Neck Surgery, Mayo Clinic, Rochester, MN 55905, USA.
Cochlear Ltd., Advanced Innovation, 2800 Mechelen, Belgium.
Audiol Res. 2025 Apr 12;15(2):41. doi: 10.3390/audiolres15020041.
BACKGROUND/OBJECTIVES: Electrode impedance is crucial for optimizing cochlear implant (CI) stimulation and hearing outcomes. While typically stable, some patients experience unexplained impedance fluctuations. This study used electrode impedance subcomponent analysis to identify the subcomponents contributing to these impedance fluctuations.
This study analyzed clinical electrode impedances and transimpedance matrix (TIM) measurements in 10 CI patients with Nucleus devices (CI422, CI522, or CI622 electrode arrays) who exhibited fluctuating or rising electrode impedances. TIM measurements used a cathodic-leading biphasic pulse (110 CLs, 75 µs/phase, 7 µs interphase interval). Electrode impedances were determined at 6, 12, 18, 24, and 75 µs, and subcomponents (access resistance [near-field/far-field] and polarization impedance [Warburg capacitance/Faraday resistance]) were calculated.
Both access resistance and polarization impedance changes contributed to impedance fluctuations. Large changes in near-field resistance compared to far-field resistance were associated with increased resistance to current flow closer to the surface of the electrode. The decreased double-layer capacitance and slightly increased Faraday resistance further suggested increased resistance to charge transfer at the electrode-electrolyte interface.
Electrode impedance subcomponent analysis reveals changes in the electrochemical reaction at the electrode surface that cause fluctuating or rising CI electrode impedances.
背景/目的：电极阻抗对于优化人工耳蜗（CI）刺激和听力结果至关重要。虽然通常较为稳定，但一些患者会出现无法解释的阻抗波动。本研究采用电极阻抗子成分分析来识别导致这些阻抗波动的子成分。
本研究分析了10名使用Nucleus设备（CI422、CI522或CI622电极阵列）且电极阻抗出现波动或上升的CI患者的临床电极阻抗和跨阻抗矩阵（TIM）测量值。TIM测量采用阴极领先双相脉冲（110个CLs，每相75µs，相间间隔7µs）。在6、12、18、24和75µs时测定电极阻抗，并计算子成分（接入电阻[近场/远场]和极化阻抗[Warburg电容/法拉第电阻]）。
接入电阻和极化阻抗的变化均导致了阻抗波动。与远场电阻相比，近场电阻的大幅变化与靠近电极表面处电流流动阻力增加有关。双层电容的降低和法拉第电阻的略微增加进一步表明电极-电解质界面处电荷转移阻力增加。
电极阻抗子成分分析揭示了电极表面电化学反应的变化，这些变化导致了CI电极阻抗的波动或上升。
