大鼠坐骨神经时间相干电场刺激建模与仿真

外周神经无损电刺激在康复医学和神经痛治疗领域有十分重要的应用。为实现无损外周神经刺激，研究了时间相干（TI）电场在大鼠下肢导电模型中的3D分布。利用多物理场仿真软件COMSOL进行有限元分析，按照适合外周神经TI刺激的电极布置方法，首先计算并分析TI电场包络调制幅度（EMA）的3D分布，随后对EMA峰值位置和电流比的关系进行拟合，并且对比了电极面积和电极间距对刺激效果的影响；最后，用同尺寸的导电体模进行实验，验证了仿真结果。实验结果表明，在刺激电极对连线上具有明显的EMA峰值，其位置相对电极对连线中间位置的偏移量[xd]与两刺激电流比n呈指数函数关系，当电极面积取3.14mm2和电极间距取8mm时，[xd=3.54e0.04n-5.12e-0.34n]（mm）。此外，电极间距对EMA峰值及EMA峰值位置受电流比控制的灵敏度有显著影响。在适当的电极布置下TI方法可以在大鼠下肢建立起EMA峰值，该峰值可以受控移动到坐骨神经部位，从而对其产生选择性刺激。

Modeling and Simulation of Rat Sciatic Nerve Stimulation via Temporally Interfering Electric Field

Non-invasive peripheral nerve electrical stimulation has very important applications in rehabilitation and treatment of neuropathic pain. The 3D distributions of temporally interfering（TI） electric field in the conduction model of rat thigh were studied to achieve noninvasive peripheral nerve stimulation. Finite element analysis was conducted using multiphysics simulation software COMSOL.First， the 3D distributions of envelop modulation amplitude（EMA） of TI electric field were calculated based on optimal electrode placement that is favorable to peripheral nerve TI stimulation. Then the relationship between EMA peak and current ratio was fitted and the effects of electrode area and electrode spacing were explored.Finally， Experiments on the conducting phantom that had the same size of the simulation model were performed and the validity of simulation results was verified.The results showed that a remarkable EMA peak occurred along the line that directly connects two electrode pairs. Besides，the relationship between [xd]，the deviation of envelope peak location from the center of the line that directly connects two electrode pairs， and n ，the ratio of two currents， could be described by the exponential function. When the electrode size was 3.14 mm2 and electrode spacing was 8 mm， [xd=3.54e0.04n-][5.12e-0.34n]（mm）. Additionally， the electrode spacing had significant influence on the EMA peak and sensitivity of controlling the EMA peak location by adjusting current ratio. The EMA peak could be established in the rat thigh with appropriate electrodes placement when deploying TI method. The location of this peak could be shifted to the sciatic nerve to achieve selective stimulation consequently.