在有源植入式医疗设备成为全球热点的今天，感应式经皮能量传输技术因能有效延长植入设备的使用寿命而得到广泛关注。但是，该技术在近年临床实践中暴露出严重的热伤害风险，引发多例病人烫伤，制约了技术的持续发展和应用推广。在此背景下，本文成功开发一个感应式经皮能量传输平台，通过计算仿真、离体模型、动物实验、临床实验等系列工作对热安全性问题展开系统化研究，为众多有源植入式医疗设备提供安全、可靠、稳定的能量供给方式。本文首先建立一套通用的闭环经皮能量传输系统，分析引起组织温升的热量源头。系统采用闭环功率控制，可实现不同耦合条件下的稳定能量传输，满足大部分有源植入设备的功耗需求。基于水浴实验分别标定体内外装置产热的功率，详细分析各部件的功耗。建立仿真模型，计算生物组织的比吸收率，确定组织直接吸收的电磁场能量及其引起的温升。其后研究能量传输热源影响下的组织温度分布，确定最恶劣区域。通过明胶与植物油的不同配比，分别制备肌肉及脂肪模拟材料，设计并搭建离体分层模型。实验测量不同影响因素下（充电功率、横向偏移及散热条件）经皮能量传输引起的植入物周围温度分布，推断温度最高点易发于植入物顶部。为此设计相应的无线测温功能，创造性地提出接收功率与植入物温度双闭环的经皮能量传输方案：调整体内充电功率以改变设备功耗及发热量，调控植入物温度；调整体外发射功率以确保植入物接收功率恰好满足充电所需，维持稳定的能量传输。在温度双闭环调控之外，添加冗余的软硬件温度保护功能，进一步提升系统的热安全性。以猪为植入对象开展活体实验，分别运用光纤测温、无线测温等手段，对植入过程中及稳定后的长期能量传输发热进行深化研究。测量并验证温升最恶劣区域，对比活体平台与离体平台的温度分布，分析血流散热及基础体温的影响，探讨皮肤温度与植入物温度的相关性，验证双闭环能量传输系统的热安全性。最后，基于经皮能量传输方案，研制用于帕金森病治疗的可充电式脑深部刺激器并投入临床试验。通过红外测温、用户问卷调查及大量人体充电数据的统计分析，证明了本系统的安全性及有效性，确定了充电效率的显著影响因子，并据此提出相应的充电设备操作建议。
Transcutaneous energy transmission (TET) via electromagnetic induction is attracting increasing attention for its great advantage in reducing active implantable medical devices’ (AIMDs’) battery size and extending their useful life. However, thermal hazards come also during TET, resulting in several patients’ skin burns in recent clinical practice, which has seriously hampered the continued development and application of the technology. This dissertation successfully developed a double closed-loop TET platform, and conducted a series of exploration into the thermal safety issues, including computer simulation, in vitro experiments, in vivo experiments and clinical trials, in order to provide a safe, reliable and stable energy supply method for varied AIMDs.A versatile closed-loop TET platform was designed and fabricated, with outstanding performance and sufficient transmission power for most TET systems. The heat production rates from implants and external coils were determined by bath experiments, while the specific absorption rate (SAR) for biological tissue was measured by computer simulation. After comparative analysis, the main heat source was determined.The temperature distribution in the implant’s vicinity was analyzed and the worst temperature area was determined. After making tissue mimicking materials for muscle and fat, a multi-layer model was built to simulate the actual thermal environment in a human body. In vitro experiments were carried out to measure the surrounding temperature distribution under different conditions during TET process, and the highest temperature was localized close to the implant device’s top surface.Based on the wireless temperature measurement technology, the double closed-loop TET scheme was proposed which consists of synchronous thermometry outer loop and received power inner loop. The charging power for implant battery would be adjusted to change the device power loss and corresponding heat production, in order to regulate the implant’s temperature; while the transmit power from external coils would be adjusted to ensure that the implant’s received power could just satisfy the charging power need, in order to maintain stable energy transmission.In vivo experiments were carried out in swine. The tissue temperature distribution was measured using an optical fiber thermometer immediately after implant surgery. Based on wireless thermometry, the implant device’s temperature rise was monitored during the long-term implantation, and compared with the temperature rise gained from in vitro experiments, in order to analyze the effect of blood flow and the base body temperature. Then, the relationship between the implant’s temperature and the skin temperature was explored, and an additional temperature protection was built based on skin temperature. The thermal safety of the double closed-loop TET system was verified to provide basis for the subsequent clinical experiments.Finally, upon the TET scheme, the rechargeable deep brain stimulator was developed for the treatment of Parkinson’s disease and put into clinical trials. Through infrared thermometry, users’ questionnaires and statistical analyses on a large number of human charging data, the TET system was proved safe and effective. The significant influence factors of charging efficiency were determined by analysis of variance, and the operational recommendations for using similar charging equipment were provided accordingly.
