Banca de QUALIFICAÇÃO: JOSÉ GARIBALDI DUARTE JÚNIOR

Analysis and Design of New Resonators for Power Transmission Systems Wireless Energy Applied in Implantable Medical Devices

Implantable Medical Devices, Wireless Energy Transfer, Planar Microwave Resonators, Non-Radiative Technique. Efficiency.

The use of modern technologies that help and improve applications related to health care and other life sciences is increasing. Over the past few years, implantable medical devices have been applied to aid in diagnostic, prognostic and medical treatment tasks. A large part of these devices need a form of energy supply to perform their functions, which in most cases is done through the use of batteries, in turn being necessary to replace them periodically, thus causing possible invasive procedures. The wireless power transfer technology (WPT) used in this scenario presents itself as a good alternative solution. Its use makes it possible to transmit portions of energy from a source to a load through a medium without the need for a direct connection between the parts. Therefore, the application of this technology in the task of powering implantable medical devices can eliminate the use or increase the useful life of batteries, depending on their functionality. In this thesis, new wireless energy transfer systems with direct application in implantable medical devices are discussed, with the main objective of proposing unprecedented microwave planar resonators with operation in the frequency band intended for medical applications. The development takes place through the analytical and parametric study of the proposed models through electromagnetic simulation computational tools. Several issues are analyzed, including operating frequency, physical dimensions, efficiency, sensitivity to distance, misalignment and relative inclination between the resonators, and safety parameters, such as the specific absorption rate (SAR) and maximum allowed input power. The analyzes are performed considering the model and composition of human surface tissues with their respective electrical, magnetic and density characteristics. Experiments on an initial set of proposed resonators are presented, obtaining an average energy transfer efficiency measured above 50% with a distance between the implanted primary and secondary resonator of 8 mm. Through simulation, it was possible to establish a maximum input power of 120 mW for safe operating conditions, that is, SAR lower than 2.0 W/kg. These results are quite promising in relation to the state of the art. As well as the study and development of other models, this work also proposes the fabrication of a rectifier for investigation of RF-DC efficiency and production of other complementary analyses.