Efficient Wireless Powering of Biomedical Sensor Systems for Multichannel Brain Implants
Efficient Wireless Powering of Biomedical Sensor Systems for Multichannel Brain Implants
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DOI：
10.1109/tim.2015.2482278
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发表时间：
2016-04-01
影响因子：
5.6
通讯作者：
Reindl, Leonhard
中科院分区：
文献类型：
--
作者：
Stoecklin, Sebastian;Yousaf, Adnan;Reindl, Leonhard
本文描述了一种适用于植入式生物医学系统的感应供电系统的完整数学优化过程。因此，优化的目标是尺寸、能量效率和组织吸收。在第一步中，通过有限元模拟计算工作频率对给定量的影响，得出无线链路的功率传输效率和可接受的组织加热在特定吸收率方面的折衷。所有的模拟都考虑了人类头部的分层结构，模拟了具有Cole-Cole色散效应的介电特性。在第二步中，将传输线圈的相关耦合和损耗效应建模为几何设计参数的函数，从而在给定外部尺寸约束的情况下，实现对最佳线圈几何形状的非迭代和可理解的数学推导。进一步的优化链路设计研究还考虑在初级线圈上应用高磁导率结构，通过增加互感来提高效率。因此，使用10毫米平面接收线圈，在线圈分离距离为5毫米时可实现80%的最终链路效率，在线圈分离距离为20毫米时可实现20%的最终链路效率，有助于提高多通道脑植入传感器的集成密度。此外，所给出的程序不仅可以深入了解线圈设计的优化，而且还为设计高效的初级侧线圈驱动器和选择次级侧阻抗匹配元件提供了一组最小的数学表达式。所有的数学模型和描述都经过了仿真和总结测量的验证。
This paper describes the complete mathematical optimization process of an inductive powering system suitable for the application within implanted biomedical systems. The optimization objectives are thereby size, energy efficiency, and tissue absorption. Within the first step, the influence of the operational frequency on the given quantities is computed by means of finite element simulations, yielding a compromise of power transfer efficiency of the wireless link and acceptable tissue heating in terms of the specific absorption rate. All simulations account for the layered structure of the human head, modeling the dielectric properties with Cole-Cole dispersion effects. In the second step, the relevant coupling and loss effects of the transmission coils are modeled as a function of the geometrical design parameters, enabling a noniterative and comprehensible mathematical derivation of the optimum coil geometry given an external size constraint. Further investigations of the optimum link design also consider high-permeability structures being applied to the primary coil, enhancing the efficiency by means of an increased mutual inductance. Thereby, a final link efficiency of 80% at a coil separation distance of 5 mm and 20% at 20 mm using a 10-mm planar receiving coil can be achieved, contributing to a higher integration density of multichannel brain implanted sensors. Moreover, the given procedure does not only give insight into the optimization of the coil design, but also provides a minimized set of mathematical expressions for designing a highly efficient primary side coil driver and for selecting the components of the secondary side impedance matching. All mathematical models and descriptions have been verified by simulation and concluding measurements.