Safety Evaluation of Medical Implants in the Human Body for a Wireless Power Transfer System in an Electric Vehicle

Abstract

One of the important safety aspects regarding electromagnetic fields is their coupling with medical implants in the human body. In this article, an adult model (Ella), with different medical implants, was exposed to a leaked magnetic field from a wireless power transfer (WPT) system in an electric vehicle, operating at a frequency of 85 kHz, with transferred powers of 3.7, 7.7, 11, and 22 kW. The induced electric field (E-field) in the human model, standing close to the vehicle and sitting inside the vehicle, was evaluated with a prosthetic hip implant, an interlocking nail implant, an InterStim neurostimulator implant, a traditional pacemaker implant, and a leadless pacemaker implant. The results indicated that medical implants influenced the maximum magnitude of the induced E-field and its distribution inside the body. A notable enhancement in the E-field was observed around the implants. In worst-case scenarios, the effects of implant shape and size were investigated. The highest induced E-field (12.68 V/m) was observed with the interlocking nail of length 340 mm for standing posture, which exceeded the prescribed limit of 11.5 V/m in the International Commission on Non-Ionizing Radiation Protection guidelines. The presence of a medical implant in the body likely limits the transferred power of the WPT system, depending on the implant type, size, location, and the body posture.