外部电场作用下的视神经纤维兴奋性的仿真研究
发布时间：2019-05-29 20:07
【摘要】：基于刺入式电极的视神经视觉假体,为盲人的视觉修复提供了新的可能性。为了对该视神经假体的电刺激策略和微电极设计提供理论支持,基于真实的电极结构,在COMSOL软件中建立刺入式微电极的外部电场仿真模型,并将其与利用NEURNO软件实现的神经纤维双层电缆模型结合,系统地研究电极与视神经纤维的相对位置、电刺激脉冲宽度以及电极几何结构的改变对视神经纤维兴奋阈值的影响。不同电极位置、刺激脉宽刺激下阈值变化规律的仿真结果,与以往报道的动物实验和仿真实验结果相符,证明了所建模型的有效性。根据仿真结果,对刺入式视神经假体中刺激脉宽的选择和电极几何结构的设计,建议如下:窄脉宽刺激有利于降低能量消耗;电极锥度的设计要在满足电极力学特性及易于植入视神经的基础上,尽可能地减小,以降低纤维兴奋的阈值;电极的暴露面积越小,纤维兴奋所需的电流阈值越低,但电荷密度阈值越高;较低的电流阈值有利于减少能量消耗,但过高的电荷密度阈值却容易造成组织损伤,因此电极暴露面积的设计需要在耗能与安全性之间进行综合考虑。电极绝缘层厚度的改变对视神经纤维的兴奋阈值没有明显的影响,但从电极插入的难易考虑,应尽可能减小绝缘层厚度。以上结果对人体其他部位神经纤维的电刺激同样具有参考价值。
[Abstract]:The optic nerve visual prosthesis based on punctured electrode provides a new possibility for visual repair of blind people. In order to provide theoretical support for the electrical stimulation strategy and microelectrode design of the optic nerve prosthesis, based on the real electrode structure, the external electric field simulation model of the punctured microelectrode was established in COMSOL software. Combined with the double-layer cable model of nerve fiber realized by NEURNO software, the effects of the relative position of electrode and optic nerve fiber, the width of electrical stimulation pulse and the geometric structure of electrode on the excitation threshold of optic nerve fiber were studied systematically. The simulation results of threshold variation under different electrode positions and stimulation pulse width are consistent with the results of animal experiments and simulation experiments reported in the past, which proves the effectiveness of the model. According to the simulation results, the selection of stimulation pulse width and the design of electrode geometry in punctured optic nerve prosthesis are suggested as follows: narrow pulse width stimulation is beneficial to reduce energy consumption; The design of electrode taper should be reduced as much as possible on the basis of satisfying the mechanical properties of electrode and easy to be implanted into optic nerve, in order to reduce the threshold of fiber excitation. The smaller the exposure area of the electrode is, the lower the current threshold needed for fiber excitation is, but the higher the charge density threshold is. Lower current threshold is beneficial to reduce energy consumption, but excessive charge density threshold is easy to cause tissue damage, so the design of electrode exposure area needs to be considered comprehensively between energy consumption and safety. The change of the thickness of the electrode insulation layer has no obvious effect on the excitation threshold of the optic nerve fiber, but it is difficult to consider from the electrode insertion, so the thickness of the insulation layer should be reduced as much as possible. The above results also have reference value for electrical stimulation of nerve fibers in other parts of human body.
【作者单位】： 上海交通大学生物医学工程学院;北京大学工学院生物医学工程系;
【基金】：国家重点基础研究发展计划(973计划)(2011CB7075002/5,2011CB013304) 国家自然科学基金(61171174)
【分类号】：R318.18;TP391.9
本文编号：2488192
[Abstract]:The optic nerve visual prosthesis based on punctured electrode provides a new possibility for visual repair of blind people. In order to provide theoretical support for the electrical stimulation strategy and microelectrode design of the optic nerve prosthesis, based on the real electrode structure, the external electric field simulation model of the punctured microelectrode was established in COMSOL software. Combined with the double-layer cable model of nerve fiber realized by NEURNO software, the effects of the relative position of electrode and optic nerve fiber, the width of electrical stimulation pulse and the geometric structure of electrode on the excitation threshold of optic nerve fiber were studied systematically. The simulation results of threshold variation under different electrode positions and stimulation pulse width are consistent with the results of animal experiments and simulation experiments reported in the past, which proves the effectiveness of the model. According to the simulation results, the selection of stimulation pulse width and the design of electrode geometry in punctured optic nerve prosthesis are suggested as follows: narrow pulse width stimulation is beneficial to reduce energy consumption; The design of electrode taper should be reduced as much as possible on the basis of satisfying the mechanical properties of electrode and easy to be implanted into optic nerve, in order to reduce the threshold of fiber excitation. The smaller the exposure area of the electrode is, the lower the current threshold needed for fiber excitation is, but the higher the charge density threshold is. Lower current threshold is beneficial to reduce energy consumption, but excessive charge density threshold is easy to cause tissue damage, so the design of electrode exposure area needs to be considered comprehensively between energy consumption and safety. The change of the thickness of the electrode insulation layer has no obvious effect on the excitation threshold of the optic nerve fiber, but it is difficult to consider from the electrode insertion, so the thickness of the insulation layer should be reduced as much as possible. The above results also have reference value for electrical stimulation of nerve fibers in other parts of human body.
【作者单位】： 上海交通大学生物医学工程学院;北京大学工学院生物医学工程系;
【基金】：国家重点基础研究发展计划(973计划)(2011CB7075002/5,2011CB013304) 国家自然科学基金(61171174)
【分类号】：R318.18;TP391.9
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