Behrend Matthew R, Ahuja Ashish K, Weiland James D
Department of Electrical Engineering, University of Southern California, Los Angeles, CA 90033, USA.
IEEE Trans Biomed Eng. 2008 Mar;55(3):1056-62. doi: 10.1109/TBME.2008.915723.
With applied potential, the current distribution at the surface of a disk electrode is spatially nonuniform and time dependent. This distribution is important to control in applications that desire a uniform current density profile or minimal corrosion. We examine the current density profile of a capacitive disk electrode subjected to a voltage-step using finite element analysis software to solve the system of partial differential equations. In detailed analyses we show quantitatively that the current density shifts from peripheral enhancement to near-uniformity following 1/2 of the lumped element time constant. As charging continues, the current density is slightly enhanced in the central region. We present curves for the evolution of local "time constants" as time progresses and calculate their effective values. The model is intended to be the basis of future work to control the corrosion profile of biologically implantable electrodes of arbitrary shape. Data suggest a means to control corrosion by retarding the edges of a stimulus pulse. Additionally, smaller electrodes may be more effective in fully utilizing surface area for charge transfer due to their shorter time constants.
在施加电势时，圆盘电极表面的电流分布在空间上是不均匀的且随时间变化。在期望均匀电流密度分布或最小腐蚀的应用中，这种分布的控制很重要。我们使用有限元分析软件求解偏微分方程组，研究了施加电压阶跃的电容性圆盘电极的电流密度分布。在详细分析中，我们定量地表明，在集总元件时间常数的1/2之后，电流密度从周边增强转变为接近均匀。随着充电的继续，中心区域的电流密度略有增强。我们给出了局部“时间常数”随时间演变的曲线，并计算了它们的有效值。该模型旨在作为未来控制任意形状生物可植入电极腐蚀分布工作的基础。数据表明了一种通过延迟刺激脉冲边缘来控制腐蚀的方法。此外，较小的电极由于其较短的时间常数，在充分利用表面积进行电荷转移方面可能更有效。
