视觉假体电刺激电流波形的改进研究

Research on Improvement of Electrical Stimulation Current Waveform for Visual Prosthesis

目的提出一种设计视觉假体电刺激电流波形的新方法,以减少电极上的峰值电压。方法电极-组织界面等效为RC电路模型;线性下降波形后加入零阶保持器来获得规则采样的零阶保持波形,借助传递函数在Simulink下仿真新设计的电流波形和恒定电流刺激波形在RC模型上引起的电压变化。结果改进后的刺激相波形包括给定数目的一些等时间分段常数段。使用改进的五段阶梯电流波形可使电极峰值电压减少大约12%。结论 Simulink仿真结果说明,使用分段的阶梯电流波形可以减少峰值电压,本研究将会给未来设计改进电流波形提供一定的指导意义。

Objective To propose a new method in designing the current waveform to minimize the peak elec trode voltage in the stimulation of visual prosthesis. Methods The electrodetissue interface was modeled as an equivalent RC circuit. The zeroorder hold was added after the decaying ramp waveform to achieve a regularly sampled zeroorderhold waveform. With the help of transfer function, the new waveform was simulated in the Simulink and the voltage on the electrode was compared with the constant current waveform. Results The stim ulation phase waveform comprised a given number of piecewise constant segments of equal duration. The im proved fivestep current waveforms could result in a 12% reduction in maximum electrode voltage. Conclusion Simulink results indicate that a voltage reduction can be achieved using current waveforms with several steps. This may provide reference for the design and improvement of the stimulating current waveform.