Metamaterial-based Compact and Efficient Wireless Power Transfer System for Biomedical Implants

我们开发了一种低磁损耗的超表面，并利用它设计了一种紧凑的生物医学植入物WPT系统。我们还提出了低电感值的设计理论，以克服频移和失调的问题。我们通过在普通杂货店购买的鸡肉进行实验来验证所提出的设计。所提出的系统的性能如预期的那样令人满意。本文介绍了一种紧凑、高效的谐振移不敏感无线电力传输系统。这可以通过使用小电长度缺陷接地结构（DGS）谐振器来实现，该谐振器可以有效地对抗由组织的高介电常数引起的谐振移位现象。组织对WPT系统有两个不希望的影响：(i)降低耦合质量因子，（ii）导致失配损失的自共振移位。因此，WPT系统的效率在组织环境中会降低。然后，使用小电长DGS，我们构建了一个WPT发射机（TX），使用三个合作的DGS谐振器来缓解这两个问题。制造的原型在空气和组织中以49兆赫的频率工作。结果表明，当同一接收机（Rx）放置在空气中或嵌入组织中时，其工作频率没有变化，这证明了所提出的DGS-WPT协同系统对谐振移位的有效性。当RX嵌入组织中时，测量到的效率为62%，在空气中为68%。

We have developed a metasurface of low magnetic losses and employed it to design a a compact WPT system to biomedical implants. We have also proposed the design theory of a low inductance value to overcome the problem of frequency shifting and misalignment. We verified the proposed design by conducting experiments using chicken meat bought at an ordinary grocery shop. The performance of the proposed system was satisfactory as expected.This brief presents a compact and efficient resonance-shift insensitive wireless power transfer (WPT) system. This is possible by using a small electrical length defected ground structure (DGS) resonator, which is found effective against the resonance-shift phenomenon resulted from the higher permittivity of the tissue. Tissue has two undesired effects on a WPT system: (i) reduced coupled quality factor, and (ii) self-resonance shifting that leads to mismatch loss. So, the efficiency of a WPT system degrades in a tissue environment. Then, using the small electrical length DGS, we build a WPT transmitter (TX) using three cooperative DGS resonators to mitigate both issues. The fabricated prototype operates at 49 MHz in the air and tissue. This shows no change in operating frequency when the same receiver (Rx) is kept in the air or embedded inside tissues, which proves the effectiveness of the proposed cooperative DGS-WPT system against the resonance shift. The measured efficiency is 62% when the RX is embedded inside the tissue and is 68% in the air.