植入式无线通信技术是有源植入式医疗器械的核心技术之一。随着植入系统网络化、小型化，低功耗、高速率的植入式无线通信技术成为当前研究热点。植入式射频通信技术在数据传输速率、可靠连接距离上具备优势，是植入式无线通信技术发展的先导技术。人体组织对植入式天线性能的影响，将导致植入式射频通信链路效率降低，影响系统功耗。这是实现低功耗植入式射频通信的主要挑战。针对人体组织对有源植入式医疗器械天线性能的影响问题，本文以神经电刺激器为研究对象，采用数值模拟、实验测试方法，研究了人体组织对神经电刺激射频通信天线链路效率的影响规律，为神经电刺激器小型化、高效率植入式天线设计提出了较系统的解决方案：（1）人体组织中植入式天线小型化、链路效率设计的本质是人体组织作为介质加载情况下的天线阻抗、增益、极化特性设计，本文构建了人体植入式天线数值模拟环境，归纳了植入式天线研究方法，搭建了神经电刺激器植入式天线研究平台，为神经电刺激器天线及其临床应用提供了设计、测试方法与技术。（2）将双模式天线应用于神经电刺激器植入式天线设计，并提出阻抗协同匹配设计方案，解决了神经电刺激器植入式天线在高介电系数比的两种人体组织中的调谐问题。相比传统的神经电刺激器天线，优化设计后的G102RS型号神经电刺激器天线，在肌肉组织中的链路效率提升了11 dB。（3）将可调匹配电路应用于神经电刺激器植入式天线调谐，并提出了植入式可重构匹配天线设计方案，系统性地解决了在复杂人体组织中，植入式天线调谐难题。采用可重构匹配设计的神经电刺激器天线，链路效率提升了6~12 dB。（4）将微带天线应用于神经电刺激器植入式天线设计，不仅解决了神经电刺激器高增益、圆极化天线设计问题，而且针对微带天线临床应用中存在制造问题，讨论了工艺设计方案，为神经电刺激器微带天线的临床应用提供了技术指导。基于上述研究，人体组织中植入式天线阻抗匹配优化设计方案已应用于G102RS型号神经电刺激器403 MHz天线设计。神经电刺激器植入式天线测试方法与技术，已应用于G122R型号神经电刺激器2.4 GHz单极子天线的临床测试与优化设计。采用植入式微带天线方案的神经电刺激器正在开展研制。
Implantable wireless communication technology is one of the key technologies for active implantable medical devices. Low-power, high-speed implantable wireless communication for the miniaturized and networked implants has become an important research field. Implantable radio frequency (RF) communication technology has advantages in data rate and reliable connection distance, which makes it suitable for implantable applications. The critical challenge of implantable RF communication is the influences of the dielectric properties of human tissue on the performance of implantable antennas, along with the design and fabrication of implantable RF transmission systems.In this thesis, the simulation and experiment platforms were built to study the design method of the implantable antenna for neurostimulators. Several solutions for the design of miniaturized and efficient implantable antenna for neurostimulators were proposed.(1) Established the research platform for the implantable antenna design of neurostimulators, including the simulation configuration method and experimental environment setup steps. The research platform was used to study the impedance, gain, and polarization properties of implantable neurostimulator antennas. This work provided design guidance and techniques for the clinical application of neurostimulator antennas.(2) Proposed a co-matching method for the neurostimulator dual-mode antenna design to solve the frequency detuning problem in two different tissues with the large Max-to-Min Permittivity Ratio. The performance of the dual-mode antenna with co-matching design has been verified by simulation and measurement. The results indicate that the risk of frequency detuning of the antenna in obese and slim patients’ bodies was significantly reduced. Meanwhile, in comparison to traditional neurostimulator antennas, the efficiency of the proposed antenna was improved. As a result, 11 dB benefit of link budget is achieved for the G102RS model neurostimulator in muscle tissue.(3) To further solve the frequency detuning problem of implantable antennas in tissues with various dielectric properties, a reconfigurable antenna design method was proposed in this thesis. The tunable matching circuit was used in the reconfigurable design. The efficiency of the RF link in varying biological environments has been significantly improved. And 6-12 dB benefit of link budget is achieved for the proposed reconfigurable antenna.(4) The design of the microstrip antenna was also investigated for neurostimulators to improve the gain of implantable antennas and achieve circular polarization design. For the biocompatible design of the microstrip antenna, the manufacture process and method were developed. These studies provided technical guidance for the clinical application of microstrip antennas for neurostimulators.In conclusion, the impedance matching optimization design of the implantable antenna in human tissue has been applied to the design of the G102RS model neurostimulator 403 MHz antenna. The implantable antenna experimental method of the neurostimulator has been applied in clinical experiments to verify and optimize the G122R model 2.4 GHz antenna. The neurostimulator with the implantable microstrip antenna is also being developed.
