Theoretical analysis of electromagnetic exposure to wireless charging systems for deep-body implantable devices

Wireless Power Transfer (WPT) techniques allow significant miniaturisation of implanted medical devices. However, the electromagnetic exposure of the body tissues must be accurately accessed to ensure safe operation. This study, therefore, analyses the exposure induced by the magnetic-and electric-type antenna transmitters over the frequency range of 100-MHz-5-GHz. The normalised power absorption, specific absorption rate (SAR) and WPT efficiency are analysed and presented. The results demonstrate the existence of an optimal operating frequency at which the maximum efficiency, minimum power absorption, and low SAR are simultaneously observed.