Rozman Janez, Pečlin Polona, Mehle Andraž, Šala Martin
Centre for Implantable Technology and Sensors, ITIS d. o. o. Ljubljana, Lepi pot 11, 1000, Ljubljana, Republic of Slovenia,
Australas Phys Eng Sci Med. 2014 Sep;37(3):525-33. doi: 10.1007/s13246-014-0282-9. Epub 2014 Jun 18.
In this study, the electrochemical performance of platinum electrodes within a multi-electrode spiral cuff to be used for selective nerve stimulation was investigated. The original cuff, simplified into a half-cuff, contained a single row of nine electrodes (0.5 × 2 mm) at a distance of 2 mm from its inner surface. Cyclic voltammetry was used to investigate the electrochemical reactions at the electrode-electrolyte interface, to define a potential window within which the electrode could be safely used in selective nerve stimulation, to calculate the charge injection capacity and cathodal charge storage capacity. Voltage transients retrieved during excitation with quasitrapezoidal biphasic current pulses, tested by selective nerve stimulation of the isolated porcine left cervical vagus nerve segment, were used to determine the maximum polarization across the electrode-electrolyte interface and to calculate cathodic charge injection capacity of the electrode. The results show that the most negative and most positive potentials across the electrode-electrolyte interface reached -0.54 and 0.59 V; these did not exceed the safe potential limits for water electrolysis. Furthermore, the time integral of the cathodic current by cyclic voltammetry measured over the potential range of water electrolysis, actually representing the cathodal charge storage capacity, was approximately -4 mC cm(-2). The charge injection capacity, representing the maximum charge density injected in a current stimulation pulse, using only reversible processes, however, was around 75 µC cm(-2). In conclusion, both, the tested stimulation pulse and electrode are suitable for efficient and safe selective nerve stimulation.
在本研究中，对用于选择性神经刺激的多电极螺旋袖带内铂电极的电化学性能进行了研究。原始袖带简化为半袖带，在距其内表面2 mm处包含一排九个电极（0.5×2 mm）。采用循环伏安法研究电极 - 电解质界面处的电化学反应，确定电极可安全用于选择性神经刺激的电位窗口，计算电荷注入容量和阴极电荷存储容量。通过对分离的猪左颈迷走神经节段进行选择性神经刺激测试，在准梯形双相电流脉冲激发期间获取的电压瞬变，用于确定电极 - 电解质界面上的最大极化，并计算电极的阴极电荷注入容量。结果表明，电极 - 电解质界面上最负和最正的电位分别达到 -0.54和0.59 V；这些电位未超过水电解的安全电位极限。此外，通过循环伏安法在水电解电位范围内测量的阴极电流的时间积分，实际上代表阴极电荷存储容量，约为 -4 mC cm(-2)。然而，仅使用可逆过程时，代表电流刺激脉冲中注入的最大电荷密度的电荷注入容量约为75 µC cm(-2)。总之，测试的刺激脉冲和电极均适用于高效且安全的选择性神经刺激。
