The HEARing CRC, Carlton, Australia.
J Neural Eng. 2011 Jun;8(3):036029. doi: 10.1088/1741-2560/8/3/036029. Epub 2011 May 16.
Animal and clinical observations of a reduction in electrode impedance following electrical stimulation encouraged the development of an in vitro model of the electrode-tissue interface. This model was used previously to show an increase in impedance with cell and protein cover over electrodes. In this paper, the model was used to assess the changes in electrode impedance and cell cover following application of a charge-balanced biphasic current pulse train. Following stimulation, a large and rapid drop in total impedance (Z(t)) and access resistance (R(a)) occurred. The magnitude of this impedance change was dependent on the current amplitude used, with a linear relationship determined between R(a) and the resulting cell cover over the electrodes. The changes in impedance due to stimulation were shown to be transitory, with impedance returning to pre-stimulation levels several hours after cessation of stimulation. A loss of cells over the electrode surface was observed immediately after stimulation, suggesting that the level of stimulation applied was creating localized changes to cell adhesion. Similar changes in electrode impedance were observed for in vivo and in vitro work, thus helping to verify the in vitro model, although the underlying mechanisms may differ. A change in the porosity of the cellular layer was proposed to explain the alterations in electrode impedance in vitro. These in vitro studies provide insight into the possible mechanisms occurring at the electrode-tissue interface in association with electrical stimulation.
动物和临床观察到电刺激后电极阻抗降低，这鼓励了电极-组织界面的体外模型的发展。该模型以前曾用于显示随着细胞和蛋白质覆盖电极，阻抗增加。在本文中，该模型用于评估平衡双相电流脉冲串施加后电极阻抗和细胞覆盖的变化。刺激后，总阻抗 (Z(t)) 和接入电阻 (R(a)) 发生了大幅快速下降。这种阻抗变化的幅度取决于使用的电流幅度，在 R(a) 和电极上的细胞覆盖之间确定了线性关系。由于刺激引起的阻抗变化是短暂的，刺激停止后几个小时内阻抗恢复到刺激前的水平。在刺激后立即观察到电极表面细胞的丢失，这表明施加的刺激水平对细胞黏附产生了局部变化。在体内和体外工作中观察到类似的电极阻抗变化，从而有助于验证体外模型，尽管潜在的机制可能不同。提出细胞层的孔隙率变化来解释体外电极阻抗的改变。这些体外研究深入了解与电刺激相关的电极-组织界面可能发生的机制。
