Limits for increasing the WPT distance in AIMDs

Wireless Power Transfer (WPT) can be used in Active Implantable Medical Devices (AIMDs) to reduce battery size and/or extend durability. Typically, the power transmitter (Tx) is placed over the patient's skin during the recharge process. In this paper, we address the main challenges to overcome when trying to extend the distance between the Tx and the implant. An experimental example is presented which can deliver 5 mW at 30 cm. The specific absorption rate (SAR) was within the regulatory limits according to the evaluation performed with sim41ife software by Zürich MedTech.