Analysis of efficiency of magnetic stimulation
Analysis of efficiency of magnetic stimulation
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DOI：
10.1109/tbme.2003.818473
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发表时间：
2003-11-01
影响因子：
4.6
通讯作者：
Durand, DM
中科院分区：
文献类型：
--
作者：
Hsu, KH;Nagarajan, SS;Durand, DM
磁刺激可以无创地激活可兴奋组织。然而，这种方法需要高能量来操作，并且可能产生导致低效刺激的设备热量。本研究对磁刺激效率进行了综合优化。共测试了16781种线圈设计，以确定用于神经激励的最佳线圈几何形状和电感。计算感应电场，找出给定线圈的最佳刺激点。然后根据神经模型的跨膜反应计算磁脉冲神经激发的阈值能量。仿真结果表明，存在一个最佳电感，作为最佳脉冲持续时间的结果，对应于最小阈值能量。为了获得轴突的最大效率，需要更长的脉冲宽度，因为轴突的膜动力学较慢，线圈到光纤的距离较长，电阻-电感-电容电路的电阻(R)和电容(C)值较大。最佳几何形状的特点是最小的线圈高度，建议一个平坦的线圈设计，以获得最佳效率。最佳线圈设计的尺寸随线圈到光纤的距离增加而增加。此外，对于无限长的纤维，三叶草设计达到了最高的效率，而蝴蝶设计对于终止或弯曲纤维是最佳的。
Magnetic stimulation can activate excitable tissues noninvasively. However, this method, requires high energy to operate and can produce equipment heat that leads to inefficient stimulation. In this study, a comprehensive optimization of efficiency for magnetic stimulation has been conducted. A total of 16 781 coil designs were tested in order to determine the optimal coil geometry and inductance for neural excitation. Induced electric fields were calculated to find the optimal stimulation site (OSS) of a given coil. The threshold energy of a magnetic pulse for neural excitation was then calculated based on the transmembrane responses of a nerve model. Simulation results show that there exists an optimal inductance, as a consequence of an optimal pulse duration, corresponding to a minimum threshold energy. A longer pulse width is required to obtain the maximum efficiency for axons with slower membrane dynamics, a longer coil-to-fiber distance, and greater values of resistance (R) and capacitance (C) of the resistance-inductance-capacitance circuit. The optimal geometry features a minimum coil height, suggesting a flat coil design for optimal efficiency. The dimension of the optimal coil design increases with the coil-to-fiber distance. Moreover, the cloverleaf design achieves the highest efficiency for infinitely long fibers whereas the butterfly design is optimal for terminating or bending fibers.