Studies in RF power communication, SAR, and temperature elevation in wireless implantable neural interfaces.
Studies in RF power communication, SAR, and temperature elevation in wireless implantable neural interfaces.
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DOI：
10.1371/journal.pone.0077759
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Ibrahim TS
中科院分区：
文献类型：
--
作者：
Zhao Y;Tang L;Rennaker R;Hutchens C;Ibrahim TS
植入式神经接口被设计为提供高空间和时间精度的控制信号，实现高自由度的实时假体系统。射频（RF）无线神经接口的发展有可能扩大应用的数量，以及延长的鲁棒性和寿命相比，有线神经接口。然而，众所周知，RF信号会被身体吸收，并可能导致组织发热。在这项工作中，数值研究与分析验证进行评估的功率，发热和特定的吸收率（SAR）与人体头部内的无线射频传输。神经接口上的接收天线设计有不同的几何形状，并在大脑内的一系列植入深度处建模，以便在不违反SAR和组织温升安全法规的情况下估计最大接收功率。基于所设计的天线的尺寸，已经研究了1 GHz至4 GHz之间的频率组。正如预期的那样，模拟表明，较长的接收天线（偶极子）和较低的工作频率导致更大的功率可用性之前，违反SAR法规。对于在大脑表面上以1.24 GHz工作的15 mm偶极天线，在联邦通信委员会（FCC）SAR违规限制下可以收获730 uW的功率。在头部内部约5 cm处，该相同的天线将在违反SAR法规之前接收190 uW的功率。最后，三维生物热模拟结果表明，对于所有评估的天线和频率组合，我们在1 °C之前就达到了FCC SAR限值。很明显，通过RF为神经接口供电是可能的，但需要结合先进仿真的超低功耗电路设计来开发满足所有系统要求的功能天线。
Implantable neural interfaces are designed to provide a high spatial and temporal precision control signal implementing high degree of freedom real-time prosthetic systems. The development of a Radio Frequency (RF) wireless neural interface has the potential to expand the number of applications as well as extend the robustness and longevity compared to wired neural interfaces. However, it is well known that RF signal is absorbed by the body and can result in tissue heating. In this work, numerical studies with analytical validations are performed to provide an assessment of power, heating and specific absorption rate (SAR) associated with the wireless RF transmitting within the human head. The receiving antenna on the neural interface is designed with different geometries and modeled at a range of implanted depths within the brain in order to estimate the maximum receiving power without violating SAR and tissue temperature elevation safety regulations. Based on the size of the designed antenna, sets of frequencies between 1 GHz to 4 GHz have been investigated. As expected the simulations demonstrate that longer receiving antennas (dipole) and lower working frequencies result in greater power availability prior to violating SAR regulations. For a 15 mm dipole antenna operating at 1.24 GHz on the surface of the brain, 730 uW of power could be harvested at the Federal Communications Commission (FCC) SAR violation limit. At approximately 5 cm inside the head, this same antenna would receive 190 uW of power prior to violating SAR regulations. Finally, the 3-D bio-heat simulation results show that for all evaluated antennas and frequency combinations we reach FCC SAR limits well before 1 °C. It is clear that powering neural interfaces via RF is possible, but ultra-low power circuit designs combined with advanced simulation will be required to develop a functional antenna that meets all system requirements.
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影响因子：
5.7
作者：
DeMarco, SC;Lazzi, G;Humayun, MS
通讯作者：
Humayun, MS
影响因子：
4.6
作者：
CHEN, JY;GANDHI, OP
通讯作者：
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影响因子：
4.1
作者：
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通讯作者：
BERENGER, JP
DOI：
10.1109/tmtt.2004.832007
发表时间：
2004-08-01
影响因子：
4.3
作者：
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通讯作者：
Humayun, M
影响因子：
3.8
作者：
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通讯作者：
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