Patient imperceptible WPT for wearable/implantable medical devices

This paper studies the wireless power link for a very low power (5 mW) active implantable medical device (AIMD) with a
$25\times 25$
mm receiver coil at a long transmission distance (30 cm minimum). A 2-coil and a 3-coil (adding a resonator) links are evaluated, achieving more than 20 times higher power transfer efficiency in the 3-coil case due to the resonator. This lowers the required output power of the transmitter, simplifying its design and alleviating EM exposure and EMI levels. The presented system would allow to recharge miniaturized AIMDs in a way that is imperceptible for the patient (e.g. from behind the mattress or chair backrest) even when they are implanted deep in the body.