Design Of Ultrasonic Wireless Power Transfer System For Implantable Medical Devices

With the development of modern medical technology,active implantable medical devices(AIMDs)play an increasingly important role in the monitoring and treatment of various diseases.However,the development of these medical implants depends largely on the power supply methods that support them to work continuously in vivo.Early power supply through extracorporeal cable has been eliminated because of its high infection rate and complications after operation.For some battery-powered devices,they are not widely used due to their large size and short life.Therefore,the long-term,stable and reliable supply of power has become an urgent problem to be solved in the field of implantable medical devices.Ultrasonic transcutaneous energy transfer(UTET)is a promising wireless power transfer technology,which can provide power for active implantable medical devices to extend the life of them.This thesis mainly completed the following works: A frequency compensation strategy based on impedance phase measurement was studied because of the influence of unpredictable tissue separation on power transfer efficiency(PTE)in UTET system;A type of 1-3 PMN-PT composite ultrasonic transducer with matching layer was fabricated,due to the piezoelectric composite material with low volume density and matching with tissue acoustic impedance easily;A class E power amplifier with STM32 as the control core was designed to drive the piezoelectric transducer at the transmitting end;A impedance transformation network was designed to perform impedance matching on the receiving transducer,and an ultrasonic energy collector consisting of rectifier filter circuit,DC-DC converter and power management module was optimized to convert and store ultrasonic energy on the implant side.In this thesis,the whole experimental platform of the system was built,and the performance of the system was tested and evaluated in water bath and pork tissue energy transmission scenarios respectively.The experimental results show that the class E power amplifier and ultrasonic energy collector can work efficiently within the frequency tuning range.And the strategy based on frequency compensation is also effective in regulating PTE in the case of random changes in tissue separation.Overall,the designed system with simple structure and stable performance can basically meet the requirements of miniaturization,light weight and high efficiency of AIMDs,but there are still some room for improvement.